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1. 3 1 GNU C Compiler 3 1 1 Installing the C Compiler In Red Hat Developer Toolset the GNU C compiler is provided by the devtoolset 3 gcc package and is 3 1 2 Using the C Compiler To compile a C program on the command line run the gcc compiler as follows scl enable devtoolset 3 gcc o output_file source_file This creates a binary file named output_file in the current working directory If the o option is omitted the compiler creates a file named a out by default When you are working on a project that consists of several source files itis common to compile an object file for each of the source files first and then link these object files together This way when you change a single source file you can recompile only this file without having to compile the entire project To compile an object file on the command line run the following command scl enable devtoolset 3 gcc o object_file c source_file This creates an object file named object_file lf the o option is omitted the compiler creates a file named after the source file with the o file extension To link object files together and create a binary file run scl enable devtoolset 3 gcc o output_file object_file Note that you can execute any command using the scl utility causing it to be run with the Red Hat Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent This allows you to run a shell session with
2. Anew command alias has been added This command can be used to create an alias of an existing command New set print entry values and show print entry values commands have been added The set print entry values command accepts both compact default if needed no only and preferred as valid arguments and can be used to enable printing of function arguments at function entry The show print entry values command can be used to determine whether this feature is enabled New set debug entry values and show debug entry values commands have been added The set debug entry values command can be used to enable printing of debugging information for determining frame argument values at function entry and virtual tail call frames command has been added as an alias of shell command New set extended prompt and show extended prompt commands have been added The set extended prompt command enables support for a defined set of escape sequences that can be used to display various information The show extended prompt command can be used to determine whether the extended prompt is enabled New set basenames may differ and show basenames may differ commands have been added The set basenames may differ command enables support for source files with multiple base names The show basenames may differ command can be used to determine whether this support is enabled The default option is off to allow faster GDB operations New Command Line Options The
3. Installed Documentation strace 1 The manual page for the strace utility provides detailed information about its usage To display the manual page for the version included in Red Hat Developer Toolset type scl enable devtoolset 3 man strace See Also Section B 6 Changes in strace provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux 6 6 version of strace and the version distributed in the 2 1 release of Red Hat Developer Toolset Chapter 1 Red Hat Developer Toolset provides an overview of Red Hat Developer Toolset and more information on how to install iton your system Chapter 9 trace provides information on how to trace program library calls using the Itrace tool C and a t User Guide functions with overlapping memory regions that are not allowed by various standards 52 Chapter 9 Itrace Chapter 9 Itrace Itrace is a diagnostic and debugging tool for the command line that can be used to display calls that are made to shared libraries It uses the dynamic library hooking mechanism which prevents it from tracing calls to statically linked libraries Itrace also displays return values of the library calls The output is printed to standard error output or to a selected file Red Hat Developer Toolset is distributed with Itrace 0 7 91 9 1 Installing Itrace In Red Hat Enterprise Linux the Ltrace utility is provided by the devtoolset 3 ltrace package a
4. The mblock move inline 1limit command line option has been added which enables the user to control the maximum size of inlined memcpy calls and similar B 2 1 1 5 Link time Optimization Link time optimization LTO is a compilation technique in which GCC generates an internal representation of each compiled input file in addition to the native code and writes both to the output object file Subsequently when several object files are linked together GCC uses the internal representations of the compiled code to optimize inter procedurally across all the compilation units This can potentially improve the performance of the generated code for example functions defined in one file can potentially be inlined when called in another file To enable LTO the flto option needs to be specified at both compile time and link time For further details including interoperability with linkers and parallel execution of LTO refer to the documentation for f1to in the GCC 4 7 0 Manual Also note that the internal representation is nota Use of Link time Optimization with debug generation is not yet Supported in gcc 4 7 and 4 8 and so use of the flto and the g options together is unsupported in Red Hat Developer Toolset B 2 1 1 6 Miscellaneous Ofast is now supported as a general optimization level It operates similar to 03 adds options that can yield better optimized code butin turn might invalidate standards compliance for example ffast
5. Red Hat Developer Toolset toolchain can then also be deployed and run on multiple versions of Red Hat Developer Toolset does not replace the default system tools provided with Red Hat Enterprise Linux 6 or 7 when installed on those platforms Instead a parallel set of developer tools provides an alternative newer version of those tools for optional use by developers The default compiler and debugger for example remain those provided by the base Red Hat Enterprise Linux system What Is New in Red Hat Developer Toolset 3 1 Starting with Red Hat Developer Toolset 3 1 Dockerfiles are available for selected Red Hat Red Hat Developer Toolset 3 1 Table 1 1 Red Hat Developer Toolset Components Name Version Description Eclipse 4 4 2 An integrated development environment with a graphical user interface a GCC 4 9 2 A portable compiler suite with support for C C and Fortran binutils 2 24 A collection of binary tools and other utilities to inspect and manipulate object files and binaries elfutils 0 161 A collection of binary tools and other utilities to inspect and manipulate ELF files dwz 0 11 A tool to optimize DWARF debugging information contained in ELF shared libraries and ELF executables for size GDB 7 8 2 A command line debugger for programs written in C C and Fortran Itrace 0 7 91 A debugging tool to display calls to dynamic libraries thata program makes It can also monitor system calls executed by programs
6. grep elfutils Dockerfile 4 Change to the directory where the required Dockerfile is installed cd opt rh devtoolset 3 root usr share devtoolset 3 dockerfiles rhel7 devtoolset 3 elfutils 5 Build the container image using the docker build command docker build t devtoolset 3 elfutils 7 Replace devtoolset 3 elfutils 7 with the name you wish to assign to your resulting container image 1 8 3 Running Red Hat Developer Toolset Tools from Container Images To launch the docker formatted container image you built see Section 1 8 2 Building Container Images execute the docker run command as follows docker run t i container image bin bash 1 Substitute the container image parameter with the name of the container image you chose when building it For example to launch the container image builtin Example 1 1 Building a Container Image with a Red Hat Developer Toolset Component run the following command docker run t i devtoolset 3 elfutils 7 bin bash 1 1 9 Additional Resources For more information about Red Hat Developer Toolset and Red Hat Enterprise Linux see the resources listed below Online Documentation Red Hat Subscription Management collection of guides The Red Hat Subscription Management collection of guides provides detailed information on how to manage subscriptions on Red Hat Enterprise Linux Red Hat Developer Toolset 3 1 Release Notes The Release Notes for Re
7. 1 8 1 Obtaining Dockerfiles The Red Hat Developer Toolset Dockerfiles are provided by the devtoolset 3 dockerfiles package The package contains individual Dockerfiles for building docker formatted container images with individual components and a meta package for building a docker formatted container image with all the components offered To be able to use the Dockerfiles install this package by executing yum install devtoolset 3 dockerfiles Note that because some Red Hat Developer Toolset components depend on packages from the Optional channel the provided Dockerfiles contain instructions that enable the channel automatically 1 8 2 Building Container Images using docker formatted container images When you are ready to build your image change to the directory where the Dockerfile is installed and run the docker build command as shown in the following example Example 1 1 Building a Container Image with a Red Hat Developer Toolset Component To build a docker formatted container image for deploying the elfutils tools in a container follow the instructions below 1 Make sure you have a Docker environment set up properly on your system by following 2 Install the package containing the Red Hat Developer Toolset Dockerfiles 12 Chapter 1 Red Hat Developer Toolset yum install devtoolset 3 dockerfiles 3 Determine where the Dockerfile for the required component is located rpm qpl devtoolset 3 dockerfiles
8. Changes Since Red Hat Enterprise Linux 6 6 An umber of bugs have been fixed and many features have been added since the release of Itrace in Red Hat Enterprise Linux 6 6 A number of bugs relating to parameter passing were fixed This includes support for structures passed in registers and fixes for displaying arguments of nested calls The argument fetching backends were reimplemented to address a number of issues The tools for selecting what is traced have been improved to be more consistent It is now possible to trace calls from as well as into the main binary any shared libraries or modules loaded using the dlLopen function It also allows for using globs and regular expressions for selecting whole sets of symbols at the same time For example to trace all calls to functions named Ffunction that Libexample makes use ltrace e function libexample Rnnanaiv R Pla annne in Jareinn 2 Nh Appen dix B Changes in Version 3 0 To trace all calls to functions that Libexample exports use ltrace 1 libexample A new approach to prototype discovery has been added It allows prototype libraries to be supplied with shared libraries When a shared library is mapped in Itrace looks up the corresponding prototype library and finds its call prototypes there The syntax of prototype libraries was generalized Anew concept of lens has been introduced which separates the way data types are to be formatted from the different kinds o
9. Developer Toolset ld ld v 32 Chapter 4 binutils 4 4 Using Other Binary Tools The binutils provide many binary tools other than a linker and an assembler For a complete list of these tools see Table 4 1 Tools Included in binutils for Red Hat Developer Toolset To execute any of the tools that are a part of binutils run the command as follows scl enable devtoolset 3 tool option file_name See Table 4 1 Tools Included in binutils for Red Hat Developer Toolset for a list of tools that are distributed with binutils For example to use the o bj dump tool to inspect an object file type scl enable devtoolset 3 objdump option object_file Note that you can execute any command using the scl utility causing it to be run with the Red Hat Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent This allows you to run a shell session with Red Hat Developer Toolset binary tools as default scl enable devtoolset 3 bash To verify the version of binutils you are using at any point type the following ata shell prompt which objdump Red Hat Developer Toolset s objdump executable path will begin with opt Alternatively you can use the following command to confirm that the version number matches that for Red Hat Developer Toolset objdump objdump v 4 5 Additional Resources A detailed description of binutils is beyond the scope of this book For more info
10. Figure 3 1 C Compatibility Matrix 3 3 GNU Fortran Compiler 3 3 1 Installing the Fortran Compiler In Red Hat Developer Toolset the GNU Fortran compiler is provided by the devtoolset 3 gcc gfortran 3 3 2 Using the Fortran Compiler To compile a Fortran program on the command line run the gfortran compiler as follows scl enable devtoolset 3 gfortran o output_file source_file This creates a binary file named output_file in the current working directory If the o option is omitted the compiler creates a file named a out by default When you are working on a project that consists of several source files itis common to compile an object file for each of the source files first and then link these object files together This way when you change a single source file you can recompile only this file without having to compile the entire project To compile an object file on the command line run the following command User Guide scl enable devtoolset 3 gfortran o object_file c source file This creates an object file named object file lf the o option is omitted the compiler creates a file named after the source file with the o file extension To link object files together and create a binary file run scl enable devtoolset 3 gfortran o output_file object_file Note that you can execute any command using the scl utility causing it to be run with the Red Hat Developer Toolset binaries used in preference to
11. This is free software you are free to change and redistribute it There is NO WARRANTY to the extent permitted by law Type show copying and show warranty for details This GDB was configured as x86_64 redhat linux gnu For bug reporting instructions please see lt http www gnu org software gdb bugs gt gdb 7 4 Listing Source Code To view the source code of the program you are debugging run the following command list Before you start the execution of the program you are debugging gdb displays the first ten lines of the source code and any subsequent use of this command lists another ten lines Once you start the execution gdb displays the lines that are surrounding the line on which the execution stops typically when you seta breakpoint You can also display the code that is surrounding a particular line To do so run the command in the following form list file_name Line_number 42 Chapter 7 GNU Debugger GDB Similarly to display the code that is surrounding the beginning of a particular function run list file_name function_name Note that you can change the number of lines the List command displays by running the following command set listsize number Example 7 4 Listing the Source Code of the fibonacci Binary File The boner c file listed in Example 7 1 Compiling a C Program With Debugging and you want the gdb utility to be capable of listing the entire source code you can
12. __builtin_bswap32 and __builtin_bswap64 mxop mfma4 and Support for the XOP FMA4 and LWP instruction sets for the AMD Orochi mlwp processors mabm Enables the use of the popcnt and 1zcnt instructions on AMD processors mpopcnt Enables the use of the popcnt instruction on both AMD and Intel processors When using the x87 floating point unit GCC now generates code that conforms to ISO C99 in terms of handling of floating point excess precision This can be enabled by fexcess precision standard and disabled by fexcess precision fast This feature is enabled by default when using standards conformance options such as std c99 Vectors of type vector Long long or vector long are passed and returned using the same method as other vectors with the VSX instruction set Previously GCC did not adhere to the ABI for 128 bit vectors with 64 bit integer base types see GCC PR 4885 7 User Guide The mrecip command line option has been added which indicates whether the reciprocal and reciprocal square root instructions should be used The mveclibabi mass command line option has been added This can be used to enable the compiler to auto vectorize mathematical functions using the Mathematical Acceleration Subsystem library The msingle pic base command line option has been added which instructs the compiler to avoid loading the PIC base register in function prologues The PIC base register must be initialized by the runtime system
13. and business continues to function by utilizing a workaround Severity 4 low A general usage question report of a documentation error or a recommendation for a future product improvement For more information on determining the severity level of an issue see https access redhat com support policy severity Once the issue severity has been determined submit a service request through the Customer Portal under the Connect option or at https access redhat com support contact technicalSupport html Note that you need your Red Hat login details in order to submit service requests If the severity is level 1 or 2 then follow up your service request with a phone call Contact information and business hours are found at https access redhat com support contact technicalSupport html If you have a premium subscription then after hours support is available for Severity 1 and 2 cases Turn around rates for both premium subscriptions and standard subscription can be found at https access redhat com support offerings production sla html 16 2 Escalating an Issue If you feel an issue is not being handled correctly or adequately you can escalate it There are two types of escalations Technical escalation If an issue is not being resolved appropriately or if you need a more senior resource to attend to it 81 User Guide Management escalation If the issue has become more severe or you believe it requires a higher pri
14. and dwelf_elf_gnu_build_id The libdw library has been improved in a number of ways Support for DWZ multifile forms DW_FORM_GNU_ref_alt and DW_FORM_GNU_strp_alt is now enabled by default and is no longer experimental New functions dwarf_getalt and dwarf_setalt have been added for getting or setting the alternative debugging file used for the alt FORMs The dwfl_linux_proc_find_elf callback now finds ELF from process memory for deleted files ifthe Dwfl has a process state attached In the libdwfl library the dwfl_build_id_find_debuginfo and dwfl_standard_find_debuginfo functions now try to resolve and set an alternative debugging file The elfutils backends have been improved in a number of ways Call Frame Information CFI unwinding has been added for the ARM architecture It relies on the debug_frame section of ELF files A mode compatible with the ARM process initial register state has been added to the ARM 64 bit architecture Native and core unwinding support for the ARM 64 bit architecture has been added All separate elfutils robustify modifications have been included The elfutils robustify changes provide functional and stability fixes that are nota part of the official elfutils distribution The CVE 2014 0172 has been fixed The bug was caused by an integer overflow that led to a added before calling malloc to uncompress data B 5 Changes in GDB Red Hat Developer Toolset 3 0 is distributed with GDB 7 8
15. the yum utils package is installed and run the following command as root debuginfo install package_name For example to install debugging information for the devtoolset 3 dwz package type debuginfo install devtoolset 3 dwz Note that in order to use this command you need to have access to the repository with these packages If your system is registered with Red Hat Subscription Management enable the rhel variant rhscl version debug rpms repository as described in Section 1 4 1 Using system to the rhel x86_64 variant version debuginfo channel as described in Section 1 4 2 oo RHN Classic For more information on how to get access to debuginfo 1 6 Updating Red Hat Developer Toolset 1 6 1 Updating to a Minor Version When a new minor version of Red Hat Developer Toolset is available run the following command as root to update your Red Hat Enterprise Linux installation yum update This updates all packages on your Red Hat Enterprise Linux system including the Red Hat Developer Toolset versions of the Eclipse development environment development debugging and performance monitoring tools and other dependent packages 10 Chapter 1 Red Hat Developer Toolset Important Use of Red Hat Developer Toolset requires the removal of any earlier pre release versions of it Additionally itis not possible to update to Red Hat Developer Toolset 3 1 from a pre release version of Red Hat Developer Toolset includi
16. which makes them more specific To get the old behavior remove the line prior to using the suppressions file Anew command line option lLeak check heuristics argument has been added The option accepts a comma separated list of the following arguments stdstring length64 newarray multipleinheritance as well as all or none The default is none The option improves the way the leak checker reports on possible leaks by specifying which interior pointers are considered valid Anew command line option keep stacktraces argument has been added The option 138 Annandiv R OChannac in Vareinn 2 A Appen dix B Chan ges IN version 3 U accepts one of the following arguments alloc free alloc and free alloc then free as well as none The default is alloc then free The option controls which stack traces to keep for blocks allocated using malloc or freed using free This produces more usable errors and causes Valgrind to consume less resources Using the v or verbose option now provides more detailed information about the use of leak suppressions For each suppression the number of blocks and bytes it suppressed during the last leak search is now shown as well as the file name and line number where the suppression is defined Helgrind The use of Statically initialized mutexes and condition variables Such as PTHREAD_MUTEX_INITIALISER no longer results in false errors The use of the pthread_cond_wait function t
17. which provides a number of improvements and bug fixes over the Red Hat Enterprise Linux system versions and the version included in the previous release of Red Hat Developer Toolset Below is a comprehensive list of new features in this release B 5 1 Changes Since Red Hat Enterprise Linux 6 6 The following features have been added since the release of GDB in Red Hat Enterprise Linux 6 6 New Features Support for linespecs has been improved in particular a more consistent handling of ambiguous linespecs some support for labels in the program s source and FILE LINE support now extends to further linespecs types Breakpoints are now set on all matching locations in all inferiors and will be updated according to changes in the inferior New inferior control commands skip function and skip file have been added These commands can be uses to skip certain functions and files when stepping The info threads command now displays the thread name as set by prcti or pthread_setname_np In addition new commands thread name and thread find have been added The thread name command accepts a name as an argument and can be used to set the name of the current thread The thread find command accepts a regular expression and allows the user to find threads that match it GDB now provides support for reading and writing a new gdb_index section The command gdb add index can be used to add gdb_index to a file which allows GDB to load symbols from tha
18. 11 SystemT ap SystemTap is a tracing and probing tool that allows users to monitor the activities of the entire system without needing to instrument recompile install and reboot It is programmable with a custom scripting language which gives it expressiveness to trace filter and analyze and reach to look into the running kernel and applications SystemTap can monitor various types of events such as function calls within the kernel or applications timers tracepoints performance counters and so on Some included example scripts produce output similar to netstat ps top and iostat others include pretty printed function callgraph traces or tools for working around security bugs Red Hat Developer Toolset is distributed with SystemTap 2 6 This version is more recent than the version included in Red Hat Enterprise Linux and provides numerous bug fixes and enhancements Table 11 1 Tools Distributed with SystemTap for Red Hat Developer Toolset Name Description stap Translates probing instructions into C code builds a kernel module and loads it into a running Linux kernel stapdyn The Dyninst backend for SystemTap staprun Loads unloads attaches to and detaches from kernel modules built with the stap utility stapsh Serves as a remote shell for SystemTap stap prep Determines and if possible downloads the kernel information packages that are required to run SystemTap stap merge Merges per CPU files This script is
19. 2 Using the C Compiler To compile a C program on the command line run the g compiler as follows scl enable devtoolset 3 g o output_file source file This creates a binary file named output file in the current working directory If the o option is omitted the g compiler creates a file named a out by default When you are working on a project that consists of several source files itis common to compile an object file for each of the source files first and then link these object files together This way when you change a single source file you can recompile only this file without having to compile the entire project To compile an object file on the command line run the following command scl enable devtoolset 3 g o object_file c source_file This creates an object file named object file lf the o option is omitted the g compiler creates a file named after the source file with the o file extension To link object files together and create a binary file run scl enable devtoolset 3 g o output_file object_file _ Chapter 3 GNU Compiler Collection GCC Note that you can execute any command using the scl utility causing it to be run with the Red Hat Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent This allows you to run a shell session with Red Hat Developer Toolset g as default scl enable devtoolset 3 bash To verify the version of g
20. Browser component Split editor mode is now supported Pressing the Ctr1 _ keyboard shortcut splits the editor horizontally and Ctrl1 splits the editor vertically A dark user interface theme is now available as a technology preview Access it by selecting the Appearance preference page in the General settings Java 8 is now supported both for compiling and in generic IDE features such as for quick fixes to make use of Java 8 features for example converting anonymous class creations to lambda expressions Eclipse CDT C C Development Tooling has been updated from version 8 2 to 8 5 The three feature releases include a number of enhancements including the following Toolchain and Language definitions have been improved to allow for a better support for switching between language standard versions for example C 11 Multi process debugging has been enhanced Dynamic printf is now supported as provided by GDB 7 7 The Standalone Debugger application has been added that provides a graphical user interface for the C C debugging subset of Eclipse plug ins C attributes as defined by C 11 are now supported The auto completion and content assist features have been improved The Mylyn task management subsystem has been updated from version 3 9 1 to 3 12 This new release includes the following changes Task integration has been enhanced and now features better search and filtering options The saving and restoring of b
21. Collections documentation Additional Resources Accessing Red Hat Product Documentation stap overview SystemTap usage Using SystemTap Using Dyninst with SystemTap stap merge overview SystemTap usage Using SystemTap stap prep overview SystemTap usage Installing SystemTap stap report overview SystemTap usage Using SystemTap stap server overview SystemTap stapdyn overview SystemTap staprun overview SystemTap usage Using SystemTap stapsh overview SystemTap usage Using SystemTap strace 149 User Guide 150 Usage Using strace strings overview binutils strip overview binutils support Red Hat Developer Toolset About Red Hat Developer Toolset SystemTap docu mentation Additional Resou rces Valgrind docu mentation Additional Resources version version memstomp
22. G CC J scl enable devtoolset 3 gfortran o hello hello f This creates a new binary file called hello in the current working directory 3 3 3 Running a Fortran Program When gfortran compiles a program it creates an executable binary file To run this program on the command line change to the directory with the executable file and type file_name Example 3 6 Running a Fortran Program on the Command Line Assuming that you have successfully compiled the hello binary file as shown in Example 3 5 shell prompt hello Hello World 3 4 Additional Resources A detailed description of the GNU Compiler Collections and its features is beyond the scope of this book For more information see the resources listed below Installed Documentation gcc 1 The manual page for the gcc compiler provides detailed information on its usage with few exceptions g accepts the same command line options as gcc To display the manual page for the version included in Red Hat Developer Toolset type scl enable devtoolset 3 man gcc gfortran 1 The manual page for the gfortran compiler provides detailed information on its usage To display the manual page for the version included in Red Hat Developer Toolset type scl enable devtoolset 3 man gfortran C Standard Library Documentation Documentation on the C standard library can be optionally installed by typing the following ata shell prompt as root yum
23. Hello World C Copyright Your copyright notice _ Description Hello World in C Ansi style 2 M iostream f std include lt iostream gt main int using namespace std sint main cout lt lt Hello World lt lt endl prints l Project Explorer 5 gt return 0 F S z Hello World v Hello World C gt Hil Includes v src 89 Problems X Tas l v 6 v Hello World C cpp O items I iostream Description Resource Path Location Type std e main int Writable Smart Insert 11 4 Figure 2 1 Sample Eclipse Session Eclipse provides a graphical development environment alternative to traditional interaction with command line tools and as such it is a welcome alternative to developers who do not wantto use the command line interface The traditional mostly command line based Linux tools suite such as gcc or gdb and Eclipse offer two distinct approaches to programming Red Hat Developer Toolset is distributed with Eclipse 4 4 2 which is based on the Eclipse Foundation s Luna release train SR2 Service Release 2 Note that if you intend to develop applications for Red Hat JBoss Middleware or require support for OpenShift Tools itis Table 2 1 Eclipse Components Included in Red Hat Developer Toolset 16 Package devtoolset 3 eclipse cdt devtoolset 3 eclipse emf devtoolset 3 eclipse gef devtoolset 3 eclipse rse devtoolset 3 eclipse jgit devtoolset 3 eclipse egi
24. Red Hat Developer Toolset the memstomp utility is provided by the devtoolset 3 memstomp package and is automatically installed with devtoolset 3 toolchain as described in Section 1 5 Installing Red Hat Developer Toolset 10 2 Using memstomp To run the memstomp utility on a program you want to analyze type the following ata shell prompt scl enable devtoolset 3 memstomp program argument To immediately terminate the analyzed program when a problem is detected run the utility with the kill or k for short command line option scl enable devtoolset 3 memstomp kill program argument The use of the kill option is especially recommended if you are analyzing a multi threaded program the internal implementation of backtraces is not thread safe and running the memstomp utility on a multi threaded program without this command line option can therefore produce unreliable results Additionally if you have compiled the analyzed program with the debugging information or this debugging information is available to you you can use the debug info or d command line option to produce a more detailed backtrace scl enable devtoolset 3 memstomp debug info program argument For detailed instructions on how to compile your program with the debugging information builtin the binary file see Section 7 2 Preparing a Program for Debugging For information on how to install Note that you can execute any com
25. Red Hat Developer Toolset gcc as default scl enable devtoolset 3 bash Chapter 3 GNU Compiler Collection GCC To verify the version of gcc you are using at any point type the following ata shell prompt which gcc Red Hat Developer Toolset s gcc executable path will begin with opt Alternatively you can use the following command to confirm that the version number matches that for Red Hat Developer Toolset gcc Some newer library features are statically linked into applications built with Red Hat Developer Toolsetto support execution on multiple versions of Red Hat Enterprise Linux This adds a small additional security risk as normal Red Hat Enterprise Linux errata would not change this code If the need for developers to rebuild their applications due to such an issue arises Red Hat will signal this via a security erratum Developers are strongly advised not to statically link their entire application for the same reasons The Red Hat Developer Toolset 3 1 version of GCC adds support for Cilk an extension to the C and C languages for parallel programming which can be enabled using the fcilkplus option Anew runtime library Libcilkrts is included in this release to support Cilk The Libcilkrts library will be a part of the gcc libraries package in the future Red Hat Enterprise Linux releases but the package is not included in all supported Red Hat Enterprise Linux releases To enable dynamic linkage of bin
26. added It displays information about stack traces executable contexts recorded by Valgrind Anew monitor command v do expensive_sanity_check_general has been added It runs various consistency checks The command can be used to verify the sanity of the Valgrind heap B 10 Changes in OProfile Red Hat Developer Toolset 3 0 is distributed with OProfile 0 9 9 which provides a number of bug fixes and feature enhancements over the version included in the previous version of Red Hat Developer Toolset Below is a comprehensive list of new features in this release B 10 1 Changes Since Red Hat Developer Toolset 2 1 The following features have been added since the release of OProfile in Red Hat Developer Toolset 2 1 Anew command ocount has been added It counts the number of times particular events occur during the time a monitored command is running For example it can be used to count the number of cache misses and instructions for an application A relatively high number of cache misses when compared to instructions could indicate poor cache performance The way the operf command operates has been improved so that more accurate data is collected The improvements are mainly related to the spawning of new processes Generic AMD performance events are now provided as a fallback for newer AMD processors for which OProfile does not have explicit event sets encodings B 11 Changes in Dyninst Red Hat Developer Toolset 3 0 is distribute
27. address has been added which enables AddressSanitizer for the Linux kernel The fsanitize recover option has been improved and now allows more fine grained selection of when itis desirable to recover and when not A 3 Changes in elfutils Red Hat Developer Toolset 3 1 is distributed with elfutils 0 161 which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version and the version included in the previous release of Red Hat Developer Toolset Below is a comprehensive list of new features in this release A 3 1 Changes Since Red Hat Developer Toolset 3 0 The following features have been added since the release of elfutils 0 159 in Red Hat Developer Toolset 3 0 The following changes have been introduced in the libdw library The dwarf_cu_getdwarf and dwarf_cu_die functions have been added The non existing DW_TAG_mutable_type attribute has been removed from the dwarf h header file The handling of LZMA compressed kernel modules ko XZ is now supported The eu unstrip utility has a new option F or force for combining files with non matching ELF headers Support for the ELF v2 application binary interface on Red Hat Enterprise Linux for POWER little endian has been added A 3 2 Changes Since Red Hat Enterprise Linux 7 1 The following features have been added since the release of elfutils 0 160 in Red Hat Enterprise Linux 7 1 The following new libdw features have
28. and with Wall Wextra Wunused but set parameter This may result in new warnings in code that compiled cleanly with previous versions of GCC For example consider the following code void fn void int foo foo bar foo is never used The following diagnostic output will be produced warning variable foo set but not used Wunused but set variable To fix this issue first see if the unused variable or parameter can be removed without changing the result or logic of the surrounding code If not annotate it with __attribute__ __unused__ As a workaround you can use the Wno error unused but set variable or Wno error unused but set parameter command line option The wenum compare option causes GCC to report a warning when values of different enum types are being compared Previously this option only worked for C programs but now it works for C as well This warning is enabled by wall and may be avoided by using a type cast Casting integers to larger pointer tyoes now causes GCC to display a warning by default To disable these warnings use the Wno int to pointer cast option which is available for both C and Cre Conversions between NULL and non pointer types now cause GCC to report a warning by default Previously these warnings were only displayed when explicitly using Wconversion To disable these warnings use the new Wno conversion null command line option GCC can now warn when a class t
29. are part of binutils are now released under the GNU General Public License version 3 B 3 1 1 GNU Linker Another ELF linker gold is now available in addition to 1d the existing GNU linker gold is intended to be a drop in replacement for 1d so 1d s documentation is intended to be the reference documentation gold supports most of ld s features except notable ones such as MRI compatible linker scripts cross reference reports cref and various other minor options It also provides significantly improved link time with very large C applications Annandiy PR Chanqaac in Varcinn 2 N Appen dix B Changes in Version 3 0 In Red Hat Developer Toolset 3 0 the go1d linker is not enabled by default Users can explicitly switch between ld and gold by using the alternatives mechanism B 3 1 1 1 New Features The following features have been added since the release of binutils included in Red Hat Enterprise Linux 6 6 Anew INPUT_SECTION_FLAGS keyword has been added to the linker script language This keyword can be used to select input sections by section header flags Anew SORT_BY_INIT_PRIORITY keyword has been added to the linker script language This keyword can be used to sort sections by numerical value of the GCC init_priority attribute encoded in the section name A new SORT_NONE keyword has been added to the linker script language This keyword can be used to disable section sorting A new linker provided symbol __ ehd r_st
30. behavior by running the set print symbol off command New record instruction history and record function call history commands have been added These commands allow you to view information about an execution log without having to replay it The record instruction history command displays the execution history atinstruction granularity and the record function call history displays the execution history at function granularity The commands are only supported by the record btrace command Anew command fo has been added This commands serves as a shorter variant of the forward search command Anew command catch signal has been added This command can be used to catch signals by their names and is similar to the handle command but also allows you to attach additional conditions or commands Anewcommand maint info bfds has been added This command can be used to list all binary files BFDs opened by GDB Two new commands python interactive command and its shorter variant pi command have been added These commands allow you to start an interactive Python prompt or evaluate a Python command and print the results to standard output Anew command py command has been added This command Serves as a shorter variant of the python command command Newenable type printer name anddisable type printer name commands have been added These commands allow you to enable or disable type printers New set breakpoint condition ev
31. diagnostics report for Red Hat Enterprise Linux is required as well This report is also known as a sosreport and the program to create the report is provided by the sos package To install the sos package and all its dependencies on your system type the following at a shell prompt as root yum install sos To generate the report run as root sosreport Account and Contact Information In order to help you GSS requires your account information to customize their support as well contact information to get back to you When you contact GSS ensure you have your Red Hat customer number or Red Hat Network RHN login name 80 Chapter 16 Contacting Global Support Services Company name Contact name Preferred method of contact phone or email and contact information phone number or email address Issue Severity Determining an issue s severity is important to allow the GSS team to prioritize their work There are four levels of severity Severity 1 urgent A problem that severely impacts your use of the software for production purposes It halts your business operations and has no procedural workaround Severity 2 high A problem where the software is functioning but production is severely reduced It causes a high impact to business operations and no workaround exists Severity 3 medium A problem that involves partial non critical loss of the use of the software Thereis a medium to low impact on your business
32. executed even ifdata_public is not true Another example for data races is one thread accessing a variable x transactionally and another thread accessing it nontransactionally at potentially the same time Note that the data can be safely reclaimed using code like this assuming only one thread ever does this __transaction_atomic data_public false destruct data Here destruct does not race with potential concurrent uses of the data because after the transaction finishes itis guaranteed that data_public is false and thus data is private See the specification and the C 11 memory model for more background information about this w Ww rmm a el gt User Guide Note that even if transactions are required to virtually execute in a total order this does not mean that they execute mutually exclusive in time Transactional memory implementations attempt to run transactions as much in parallel as possible to provide scalable performance There are two variants of transactions atomic transactions __transaction_atomic and relaxed transactions __transaction_relaxed The former guarantee atomicity with regard to all other code but allow only code that is known to not include nontransactional kinds of synchronization such as atomic or volatile memory access In contrast relaxed transactions allow all code for example calls to I O functions but only provide atomicity with regard to other transactions Therefore atomic transacti
33. frame in the selected thread The gdb InferiorThread class now supports a new name attribute Support for inferior events has been added Python scripts can now add observers in order to be notified of events occurring in the process being debugged GDB commands implemented in Python can now be putin the gdb COMMAND_USER command class Themaint set python print stack on off command has been removed and replaced by set python print stack Anew class gdb printing FlagEnumerationPrinter has been added This class can be used to apply flag enun style pretty printing to enums The gdb Lookup_symbol function now works correctly when there is no current frame The gdb Symbol object now has an additional attribute Line This attribute holds the line number in the source at which the symbol was defined The gdb Symbol object now has an additional attribute needs_ frame and a new method value The needs_ frame attribute indicates whether the symbol requires a frame to compute its value and the value method computes the symbol s value The gdb Value object now has a new method referenced_value This method can be used to dereference a pointer as well as C reference values The gdb Symtab object now has two new methods global_block and static_block These methods return the global and static blocks as gdb Block objects of the underlying symbol table respectively Anew method gdb find_pc_line returns the gdb Symtab_and_1line o
34. from the C 11 ABI discussed above the Red Hat Enterprise LINUX Application Compatibility Developer Toolset with those built with the Red Hat Enterprise Linux 6 or 7 toolchain particularly O a files the Red Hat Developer Toolset toolchain should be used for any linkage This ensures any newer library features provided only by Red Hat Developer Toolset are resolved at link time A new standard mangling for SIMD vector types has been added to avoid name clashes on systems with vectors of varying length By default the compiler still uses the old mangling but emits aliases with the new mangling on targets that support strong aliases Wabi will now display a warning about code that uses the old mangling B 2 1 5 2 Miscellaneous GCC now optimizes calls to various standard C string functions such as strlen strchr 110 Appendix B Changes in Version 3 0 strcpy strcat and stpcpy as well as their respective FORTIFY_SOURCE variants by transforming them into custom faster code This means that there might be fewer or other calls to those functions than in the original source code The optimization is enabled by default at 02 or higher optimization levels It is disabled when using fno optimize strlen or when optimizing for size When compiling for 32 bit GNU Linux and not optimizing for size fomit frame pointer is now enabled by default The prior default setting can be chosen by using the fno omit frame pointer comman
35. functionally complete and is intended for production use Important bug fixes and security errata are issued to Red Hat Developer Toolset subscribers ina similar manner to Red Hat Enterprise Linux for two years from the release of each major version release Anew major version of Red Hat Developer Toolset is released annually providing significant updates for existing components and adding major new components A single minor release issued six months after each new major version release provides a smaller update of bug fixes security errata and new minor components Additionally the Red Hat Enterprise Linux Application Compatibility Specification also applies to Red Hat Developer Toolset Subject to some constraints on the use of newer C 11 language Applications and libraries provided by Red Hat Developer Toolset do not replace the Red Hat Enterprise Linux system versions nor are they used in preference to the system versions Using a framework called Software Collections an additional set of developer tools is installed into the opt directory and is explicitly enabled by the user on demand using the scl utility 1 2 Main Features The Red Hat Developer Toolset version of the GNU Compiler Collection GCC provides the following features Link time optimization LTO has been improved in a number of ways so that it is faster consumes less memory and generates smaller object files Inter procedural analysis IPA has been imp
36. increment a global variable y if another variable x has a value less than 10 __transaction_atomic if x lt 10 y This happens atomically even in a multi threaded execution of the program In particular even though the transaction can load x and y and store to y all these memory accesses are virtually executed as one indivisible step Note that in line with the C 11 memory model programs that use transactions must be free of data races Transactions are guaranteed to be virtually executed serially in a global total order that is determined by the transactional memory implementation and that is consistent with and contributes to the happens before order enforced by the rest of the program that is ttansaction semantics are specified based on the C 11 memory model see the draft specification linked above Nonetheless ifa program is not data race free then it has undefined behavior For example a thread can first initialize some data and then make it publicly accessible by code like this init data __transaction_atomic data_public true data_public is initially false Another thread can then safely use the data for instance __transaction_atomic if data_public use data However the following code has a data race and thus results in undefined behavior __transaction_atomic temp copy data if data_public use temp Here copy data races with 1nit data in the initializing thread because this can be
37. index sections on causes GDB to use any older gdb_index sections it finds If this option is set the ability to set breakpoints on inline functions is lost in symbol files with older gdb_1ndex sections The gdb_index section has also been updated to record more information about each symbol GDB now provides Ada support for GDB MI Variable Objects GDB now supports breakpoint always inserted mode in the record target gdbserver now supports evaluation of breakpoint conditions Note that you can instruct GDB to send the breakpoint conditions in bytecode form but gdbserver only reports the breakpoint trigger to GDB when its condition evaluates to true New convenience functions _memeq buf1 buf2 length streq stri str2 strlen str and _regex str regex have been added Target record has been renamed to record full Consequently you can now use the record full command to record or replay an execution log In addition the following commands have been renamed The set record insn number max and show record insn number max commands have been renamed to set record full insn number max and show record full insn number max The set record memory query and show record memory query commands have been renamed to set record full memory query and show record full memory query The set record stop at limitand show record stop at limit commands have been renamed to set record full stop at limitand show record full stop at limit
38. install devtoolset 3 libstdc docs Once installed HTML documentation is available at opt rh devtoolset 3 root usr share doc devtoolset 3 libstdc docs 4 9 1 html index html Online Documentation N i r User Guide Se 30 Red Hat Enterprise Linux 6 Developer Guide and Red Hat Enterprise Linux 7 Developer Guide The Developer Guides for Red Hat Enterprise Linux 6 and 7 provide in depth information about GCC Using the GNU Compiler Collection The official GCC manual provides an in depth description of the GNU compilers and their usage The GNU C Library The GNU C library documentation provides detailed information about the GNU implementation of the standard C library The GNU Fortran Compiler The GNU Fortran compiler documentation provides detailed information on gfortran s usage e Also Section A 2 Changes in GCC provides a list of improvements over the Red Hat Enterprise Linux 7 1 version of the GNU Compiler Collection and the version distributed in the previous release of Red Hat Developer Toolset Section B 2 Changes in GCC provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux 7 0 and 6 6 versions of the GNU Compiler Collection and the version distributed in the 2 1 release of Red Hat Developer Toolset as well as information about the language ABI and debugging compatibility Chapter 1 Red Hat Developer Toolset provides an over
39. left hand side of the dialog box click C C Build Settings 3 Selectthe Tool Settings tab 4 lf you are working on a C project a selectGCC C Compiler or Cross GCC Compiler and change the value of the Command field to usr bin gcc 18 Chapter 2 N m e fh D b select GCC C Linker or Cross GCC Linker and change the value of the Command field to usr bin gcc c select GCC Assembler or Cross GCC Assembler and change the value of the Command field to usr bin as If you are working on a C project a select GCC C Compiler or Cross G Compiler and change the value of the Command field to usr bin gt b selectGCC C Compiler or Cross GCC Compiler and change the value of the Command field to usr bin gcc c select GCC C Linker or Cross G Linker and change the value of the Command field to usr bin gt d selectGCC Assembler or Cross GCC Assembler and change the value of the Command field to usr bin as 5 Click the OK button to save the configuration changes 2 3 Additional Resources A detailed description of Eclipse and all its features is beyond the scope of this book For more information see the resources listed below Installed Documentation Eclipse includes a built in Help system which provides extensive documentation for each integrated feature and tool This greatly decreases the initial time investment required for new developers to become fluent in its use
40. on the system the Function view with a list of functions that are available on the system and can be used in Stp scripts As well this plug in includes integration for running SystemTap scripts and viewing the results in a textual tabular and graphical manner Note that the result sets are updated in a near runtime way which allows the user to use this plug in for longer running monitoring tasks New kernel perf tool integration has been added This plug in uses the performance counters subsystem of the Linux kernel to profile applications makes it easier to analyze the results by hyperlinking to the sources in the workspace projects simplifies the perf tool configuration by selecting the counters to be used and allows the user to run this tool remotely A unified profiling launcher has been added to provide a single method to launch profiling It allows the user to select a profiling category Memory Timing or Coverage and back ends for this category such as OProfile perf or GProf for Timing The C C documentation plug in has been enhanced to recognize and use gtk doc generated documentation and to display it in the Eclipse Help Center The OProfile plug in has been enhanced to support root privilege authentication through polkit This feature is configured automatically The Valgrind plug in now supports the Helgrind tool which can be used to detect synchronization problems such as race conditions deadlocks caused by inc
41. option 1 has been added This option can be used to control how interactive strace is Anew command line utility strace log merge has been added This utility can be used to merge timestamped strace output into a single file The strace utility now uses optimized interfaces to extract data from the traced process for better performance The strace utility now provides improved support for decoding of arguments for various system calls In addition a number of new system calls are supported B 6 2 Changes Since Red Hat Developer Toolset 2 1 The following features have been added since the release of strace in Red Hat Developer Toolset 2 1 When writing its output to a pipe strace now waits for the pipe process to terminate before strace itself exits Anew option e trace memory has been added It instructs strace to trace system calls related to memory mapping allocation deallocation and management A new option qq has been added It instructs strace to suppress messages about process exit Status Many bugs have been fixed and improvements added including improvements in the decoding of system call arguments and the addition of missing system calls B 7 Changes in Itrace Red Hat Developer Toolset 3 0 is distributed with Itrace 0 7 91 which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version Belowis a comprehensive list of new features in this release B 7 1
42. options Enumerated line numbers are now supported by statement probes which allows for probing discontiguous lines Use the following syntax process statement example file c 3 5 7 9 SystemTap now supports moving a probe from the specified line to the nearest line that can be probed using the following syntax statement file NUM nearest The SystemTap runtime back end staprun has been improved in a number of ways Certain probe types kprobes uprobes and timer s NUM can now be armed and disarmed on the fly Thus probe overhead can be avoided when probes are not needed Non recursive and loop free probes now have statement counting suppressed in the generated C code Counting can be turned back on in the unoptimized mode by using the u option with stap Statically Defined Tracing SDT probes with operands that refer to symbols are now supported Many new functions have been added to the tapset library and many tapsets were simplified by using the new autocast feature Incompatibility problems with old scripts can be resolved using the backward compatibility option compatible version where version is the version of SystemTap for which the script was written A 6 Changes in Valgrind Red Hat Developer Toolset 3 1 is distributed with Valgrind 3 10 1 which provides a number of bug fixes over the version included in Red Hat Enterprise Linux and the previous version of Red Hat Developer Toolset Below is a comp
43. plugin devel depend on packages that are only available in the Optional channel The name of this channel uses the following format rhel x86_64 variant optional 6 Replace variant with the Red Hat Enterprise Linux system variant server or workstation 2 Subscribe the system to the channels from step no 1 by running the following command as root rhn channel add channel channel_name Replace channel_name with the name of the channel to enable 3 To verify the list of channels you are subscribed to at any time run as root rhn channel list Once the system is subscribed you can install Red Hat Developer Toolset as described in Section 1 5 Installing Red Hat Developer Toolset For more information on how to register your 1 5 Installing Red Hat Developer Toolset Red Hat Developer Toolset is distributed as a collection of RPM packages that can be installed updated uninstalled and inspected by using the standard package management tools that are included in Red Hat Enterprise Linux Note that a valid subscription that provides access to the Red Hat Software Collections content set is required in order to install Red Hat Developer Toolset on your system For detailed instructions on how to associate your system with an appropriate subscription and get access to Red Hat Developer Toolset see Section 1 4 Getting Access to Red Hat Developer Toolset Chapter 1 Red Hat Developer Toolset Important Befo
44. run the following command to change the number of gdb set listsize 20 listed lines to 20 You can now display the entire source code of the file you are debugging by running the List command with no additional arguments gdb list 1 include lt stdio h gt 2 include lt limits h gt 3 4 int main int argc char 5 unsigned long int a 6 unsigned long int b 7 unsigned long int sum 8 9 while b lt LONG_MAX 10 printf ld b 11 sum a b 12 a b 13 b sum 14 15 16 return 0 17 7 5 Setting Breakpoints Setting a New Breakpoint To set a new breakpoint at a certain line run the following command break file_name line_number argv 0 1 You can also seta breakpoint on a certain function A A 4 2 fi ra User Guide break file_name function_name Example 7 5 Setting a New Breakpoint Assuming that you have compiled the tape need file listed in Example 7 1 Compiling a c atline 10 by running the following command gdb break 10 Breakpoint 1 at 0x4004e5 file fibonacci c line 10 Listing Breakpoints To display a list of currently set breakpoints run the following command info breakpoints Example 7 6 Listing Breakpoints Assuming that you have followed the instructions in Example 7 5 Setting a New Breakpoint you can display the list of currently set breakpoints by running the following command gdb info brea
45. stub reports support for this packet to the qSupported query Qbtrace off Disables branch tracing for the current thread The remote stub reports support for this packet to the gSupported query qXfer btrace read Reads the traced branches for the current thread The remote stub reports support for this packet to the qSupported query qXfer libraries The previously unused annex of the qXfer libraries Svr4 read s annex svr4 read packet is now used to support passing ofan argument list The remote stub reports support for this argument list to the qSupported query The defined arguments are start and prev These arguments are used to reduce work necessary for updating the library list and significantly speed up the process The z0 z1 breakpoint insertion packets have been extended to carry a list of conditional expressions over to the remote stub depending on the condition evaluation mode You can use the set remote conditional breakpoints packet command to control the use of this extension New RSP Packet Anew RSP packet has been added Anew RSP packet QProgramSignals can be used to specify the signals the remote stub can pass to the debugged program without GDB involvement Changes in the Machine Interface Interpreter GDB Ml The following MI changes have been made Anew command info os has been added as the MI equivalent of info os Output logs such as set Logging and related now include MI output A new async record cm
46. the Custom Debug Info section in the GDB manual for more information the devtoolset 3 gdb doc package needs to be installed on your system for this documentation to be locally available A 5 Changes in SystemT ap Red Hat Developer Toolset 3 1 is distributed with SystemTap 2 6 which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux 6 6 version and the version included in the previous release of Red Hat Developer Toolset Below is a list of new features in this release A 5 1 Changes Since Red Hat Developer Toolset 3 0 and Red Red Hat Enterprise Linux 6 6 The following features have been added since the release of SystemTap included in Red Hat Developer Toolset 3 0 and Red Red Hat Enterprise Linux 6 6 The SystemTap front end stap has been improved in a number of ways Anew option E script has been added which allows for specifying additional scripts Note that a main script still needs to be specified using the e option or in a file DWARF process probes can now be bound to a specific process using the following syntax process PID function SystemTap now supports probes with the following syntax User Guide process PATH library PATH plt NAME return A PID provided for a process probe is now expected by SystemTap to correspond to a running process Probes are now printed in a more consistent and precise manner when the listing mode is invoked using the 1 or L
47. the Red Hat Enterprise Linux system equivalent This allows you to run a shell session with Red Hat Developer Toolset gfortran as default scl enable devtoolset 3 bash To verify the version of gfortran you are using at any point type the following ata shell prompt which gfortran Red Hat Developer Toolset s gfortran executable path will begin with opt Alternatively you can use the following command to confirm that the version number matches that for Red Hat Developer Toolset gfortran gfortran v Important Some newer library features are statically linked into applications built with Red Hat Developer Toolset to Support execution on multiple versions of Red Hat Enterprise Linux This adds a small additional security risk as normal Red Hat Enterprise Linux errata would not change this code If the need for developers to rebuild their applications due to such an issue arises Red Hat will signal this via a security erratum Developers are strongly advised not to statically link their entire application for the same reasons Example 3 5 Compiling a Fortran Program on the Command Line Consider a source file named hello f with the following contents program hello print Hello World end program hello To compile this source code on the command line by using the gfortran compiler from Red Hat Developer Toolset type 28 Faantar 2 Cr MIICLAMHA AY A l art lt AK lo Vm 1 Cha pters G NU Com pl ler Collection
48. the restrictions of PURE Null pointers including NULL and unallocated variables can now be used as an actual argument to optional non pointer non allocatable dummy arguments denoting an absent gt D argument Non pointer variables with the TARGET attribute can now be used as an actual argument to POINTER dummies with INTENT IN Pointers that include procedure pointers and those in a derived type pointer components can now also be initialized by a target instead of only by NULL The EXIT statement with construct name can now be used to leave the ASSOCIATE BLOCK IF SELECT CASE and SELECT TYPE constructs in addition to DO Internal procedures can now be used as actual arguments The named constants INTEGER_KINDS LOGICAL_KINDS REAL_KINDS and CHARACTER_KINDS of the intrinsic module ISO_FORTRAN_ENV have been added These arrays contain the supported kind values for the respective types The C_SIZEOF module procedures of the ISO_C_BINDINGS intrinsic module and the COMPILER_VERSION and COMPILER_OPTIONS module procedures of the ISO_FORTRAN_ENV intrinsic module have been implemented The OPEN statement now supports the NEWUNIT option This option returns a unique file unit and therefore prevents inadvertent use of the same unit in different parts of the program Unlimited format items are now supported The INT 8 16 32 and REAL 32 64 128 format for ISO_FORTRAN_ENV intrinsic module type parameters are now suppo
49. uncompressed debug_strsections has been fixed The decoding of abbreviations using the DW_FORM_ref_addr attribute has been fixed The objcopy utility now supports wildcards for section names in command line options The BFD linker script language now supports the ALIGN_WITH_INPUT directive for output sections The directive directs the linker to compute the maximum alignment of the associated input sections and use that alignment for the output section The AVX 512 512 bit Advanced Vector Extensions are now supported B 4 Changes in elfutils Red Hat Developer Toolset 3 0 is distributed with elfutils 0 159 which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version and the version included in the previous release of Red Hat Developer Toolset Below is a comprehensive list of new features in this release B 4 1 Changes Since Red Hat Developer Toolset 2 1 The following features have been added since the release of elfutils 0 157 in Red Hat Developer Toolset 2 1 The libdwfl library has been improved in a number of ways Annandiy R Channac in Vlarcinn 2 N AP WJ en d 1A B onan q es IN Version 3 U The dwfl_core_file_report has a new parameter executable The following new functions have been added dwfl_module_getsymtab_first_global dwfl_module_getsym_info and dwfl_module_addrinfo An unwinder has been added with a Dwfl_Thread_Callbacks type two opaque types Dwfl_Thread an
50. 13 27 19 632240 getenv POSIXLY_CORRECT nil 13 27 19 632520 strrchr pwd nil 13 27 19 632786 setlocale LC_ALL en_US UTF 8 13 27 19 633220 bindtextdomain coreutils usr share locale usr share locale 13 27 19 633471 textdomain coreutils coreutils 13 27 19 637110 exited status 0 9 2 4 Displaying a Summary To display a summary of how much time was required to execute each system call and how many times were these system calls executed run the 1 trace utility with the c command line option scl enable devtoolset 3 ltrace c program argument Example 9 4 Displaying a Summary User Guide Consider the 1sblk command To run the Ltrace utility on this program and display a trace summary type scl enable devtoolset 3 ltrace c lsblk gt dev null time seconds usecs call calls Function 53 60 0 261644 261644 1 libc start _main 4 48 0 021848 58 374 mbrtowc 4 41 0 021524 57 374 wcwidth 4 39 0 021409 57 374 __ctype_get_mb_cur_max 4 38 0 021359 57 374 iswprint 4 06 0 019838 74 266 readdir64 3 21 0 015652 69 224 strlen 100 00 0 488135 3482 total 9 3 Additional Resources A detailed description of Itrace and its features is beyond the scope of this book For more information see the resources listed below Installed Documentation Itrace 1 The manual page for the 1 trace utility provides detailed information about its usage To display the
51. 3 redhat Red Hat Developer Toolset 3 x User Guide Installing and Using Red Hat Developer Toolset Jarom r Hrad lek Matt Newsome Robert Kr tk Red Hat Developer Toolset 3 x User Guide Installing and Using Red Hat Developer Toolset Jaromir Hradilek Red Hat Customer Content Services jhradilek redhat com Matt Newsome Red Hat Software Engineering mnewsome redhat com Robert Kratky Red Hat Customer Content Services rkratky redhat com Legal Notice Copyright 2014 2015 Red Hat Inc This documentis licensed by Red Hat under the Creative Commons Attribution ShareAlike 3 0 Unported License If you distribute this document or a modified version of it you must provide attribution to Red Hat Inc and provide a link to the original Ifthe documentis modified all Red Hat trademarks must be removed Red Hat as the licensor of this document waives the right to enforce and agrees notto assert Section 4d of CC BY SA to the fullest extent permitted by applicable law Red Hat Red Hat Enterprise Linux the Shadowman logo JBoss MetaMatrix Fedora the Infinity Logo and RHCE are trademarks of Red Hat Inc registered in the United States and other countries Linux is the registered trademark of Linus Torvalds in the United States and other countries Java is aregistered trademark of Oracle and or its affiliates XFS is a trademark of Silicon Graphics International Corp or its subsidiaries in the United States
52. A new record target record btrace has been added This target uses hardware support to record the control flow of a process and can be enabled by using the record btrace command This record target does not support replaying the execution Important The record btrace target is only available on Intel Atom processors and requires the Linux kernel in version 2 6 32 or later The epoch command line option has been removed This option was used by GDB mode in Epoch a deprecated clone of the Emacs text editor The ptype and whatis commands have been updated to accept an argument to control the type formatting The info proc command has been updated to work on some core files The cd command has been enhanced and no longer requires a directory path as its first argument When executed with no arguments the command now changes to the home directory GDB now uses GNU v3 ABI as the default C ABI This has been the default option for GCC since November 2000 122 Theinfo tracepoints command has been enhanced to display installed on targetor not installed on target for each non pending location of a tracepoint NewRemote Packets complete list Table B 3 New Remote Packets Remote Packet Description QTBuffer size Sets the size of the trace buffer The remote stub reports support for this packet to the qSupported query Qbtrace bts Enables branch tracing based on Branch Trace Store BTS for the current thread The remote
53. G include hints how to fix the bugs Consider the following code template lt typename T gt int t T 1 return f 1 int f int 1 return i int main return t 1 The following diagnostics output will be produced In instantiation of int t T with T int required from here error f was not declared in this scope and no declarations were found by argument dependent lookup at the point of instantiation fpermissive note int f int declared here later in the translation unit To correct the error in this example move the declaration of function f before the definition of template function t The fpermissive compiler flag turns compile time errors into warnings and can be used as a temporary workaround Uninitialized const Consider the following declaration Struck A ant a A struct B public A const B b le lee t Appendix B Changes in Version 3 0 An attempt to compile this code now fails with the following error error uninitialized const b fpermissive note const struct B has no user provided default constructor This happens because B does not have a user provided default constructor Either an initializer needs to be provided or the default constructor needs to be added Visibility of Template Instantiations The ELF symbol visibility of a template instantiation is now properly constrained by the visibility of its template arg
54. GCC might not always preserve data race freedom when optimizing code GCC also supports new built ins for atomic memory accesses which follow the design of the memory model and new atomic operations The former set of synchronization built ins that is those prefixed with __ sync are still supported Transactional Memory Transactional Memory TM allows programs to declare that a piece of code is supposed to execute as a transaction that is virtually atomically and in isolation from other transactions GCC s o RAR N Appendix B Changes in Version 3 0 transactional memory runtime library Libitm then ensures this atomicity guarantee when executing the compiled program Compared to atomic memory accesses it is a higher level programming abstraction because it is not limited to single memory locations does not require special data types for the data it modifies and because transactions can contain arbitrary code and be nested within other transactions with some restrictions explained subsequently GCC implements transactions as specitied in the Draft Specification for Transactional Language GCC already Spoor a C Compatible subset of the constructs when compiling C source oe The main language constructs are transaction statements and expressions and are declared by the __transaction_atomicor_transaction_relaxed keywords followed by a compound statement or expression respectively The following example illustrates how to
55. Hat Developer Toolset documentation Red Hat Product Documentation Accessing Red Hat Product Documentation DRD overview Valgrind usage Using Valgrind dwp overview binutils usage Using Other Binary Tools dwz 143 User Guide 144 Dyninst Eclipse elfedit elfutils overview dwz eu addr2line eu ar overview eliutils eu elfcmp eu elflint overview elfutils overview elfutils eu findtextrel overview elfutils eu make debug archive overview elfutils eu nm overview elfutils usage Using elfutils eu objdump overview elfutils usage Using elfutils eu ranlib overview elfutils usage Using elfutils eu readelf overview elfutils usage Using elfutils eu size overview elfutils usage Using elfutils eu stack overview elfutils eu strings overview elfutils usage Using elfutils eu strip overview elfutils usage Using elfutils eu unstrip overview elfutils Fortran programming language compiling Using the Fortran Compiler g see GNU Compiler Collection GAS see GNU assembler GCC see GNU Compiler Collection gcc see GNU Compiler Collection GDB see GNU Debugger gfortran see GNU Compiler Collection Global Support Services contacting Contacting Global Support Services GNU assembler Appendix C Revision History 145 User Guide 146 docu mentation Additional Resou rces GNU Binutils see binutils GNU Compiler Collec
56. I Because the upstream GCC community development does not guarantee C 11 ABI compatibility across major versions of GCC the same applies to use of C 11 with Red Hat Developer Toolset Consequently using the std c 11 option is supported in Red Hat Developer Toolset 3 0 only when all C objects compiled with that flag have been built using the same major version of Red Hat Developer Toolset The mixing of objects binaries and libraries built by the Red Hat Enterprise Linux 6 or 7 system toolchain GCC using the std c x or std gnu 0x flags with those built with the std c 11 or std gnu 11 flags using the GCC in Red Hat Developer Toolset is explicitly not supported As later major versions of Red Hat Developer Toolset may use a later major release of GCC forward compatibility of objects binaries and libraries built with the std c 11 or std gnut 11 options cannot be guaranteed and so is not Supported The default language standard setting for Red Hat Developer Toolset is C 98 Any C 98 compliant binaries or libraries built in this default mode or explicitly with std c 98 can be freely mixed with binaries and shared libraries built by the Red Hat Enterprise Linux 6 or 7 system toolchain GCC Red Hat recommends use of this default std c 98 mode for production software development Important Use of C 11 features in your application requires careful consideration of the above ABI compatibility information Aside
57. Profile and available tools To display the manual page for the version included in Red Hat Developer Toolset type scl enable devtoolset 3 man oprofile opannotate 1 oparchive 1 opcontrol 1 opgprof 1 ophelp 1 opimport 1 opreport 1 Manual pages for various tools distributed with OProfile provide more information on their respective usage To display the manual page for the version included in Red Hat Developer Toolset type scl enable devtoolset 3 man tool Online Documentation Red Hat Enterprise Linux 6 Developer Guide and Red Hat Enterprise Linux 7 Developer Guide 69 User Guide Red Hat Enterprise Linux 6 Deployment Guide The Deployment Guide for Red Hat Enterprise Linux 6 describes in detail how to install configure and start using OProfile on this system Red Hat Enterprise Linux 7 System Administrator s Guide The System Administrator s Guide for Red Hat Enterprise Linux 7 documents relevant information regarding the deployment configuration and administration of Red Hat Enterprise Linux 7 See Also Chapter 1 Red Hat Developer Toolset provides an overview of Red Hat Developer Toolset and more information on how to install it on your system Chapter 11 SystemTap provides an introduction to SystemTap and explains how to use it to monitor the activities of a running System Chapter 12 Valgrind explains how to use Valgrind to profile applications and detect memory errors and m
58. RIVATE MAP_DENYWRITE 3 0x3146a00000 mmap 0x3146d89000 20480 PROT_READ PROT_WRITE MAP_PRIVATE MAP_FIXED MAP_DENYWRITE 3 0x189000 0x3146d89000 mmap 0x3146d8e000 18600 PROT_READ PROT_WRITE MAP_PRIVATE MAP_FIXED MAP_ANONYMOUS 1 0x3146d8e000 mmap NULL 4096 PROT_READ PROT_WRITE MAP_PRIVATE MAP_ANONYMOUS 1 0 0x7f896C 734000 mmap NULL 4096 PROT_READ PROT_WRITE MAP_PRIVATE MAP_ANONYMOUS 1 0 0x7f896C 733000 mmap NULL 4096 PROT_READ PROT_WRITE MAP_PRIVATE MAP_ANONYMOUS 1 0 0x7f896C732000 munmap 0x7f896cC735000 61239 0 mmap NULL 4096 PROT_READ PROT_WRITE MAP_PRIVATE MAP_ANONYMOUS 1 0 0x7f896cC 743000 John john example comDoe exited with O 8 2 3 Displaying Time Stamps To prefix each line of the trace with the exact time of the day in hours minutes and seconds run the strace utility with the t command line option scl enable devtoolset 3 strace t program argument To also display milliseconds supply the t option twice scl enable devtoolset 3 strace tt program argument To prefix each line of the trace with the time required to execute the respective system call use the r command line option scl enable devtoolset 3 strace r program argument Example 8 3 Displaying Time Stamps Consider an executable file named pwd To run the strace utility on this file and include time stamps in the output type scl enable devtoolset 3
59. TAPI_RT_LIB opt rh devtoolset 3 root usr 1ib64 dyninst libdyninstAPI_RT so This sets the DYNINSTAPI RT_LIB environment variable in the current shell session Example 14 2 Using Dyninst as a Stand alone Application illustrates how to write and build a program to monitor the execution of a user space process For a detailed explanation of how to use Dyninst see the resources listed in Section 14 3 Additional Resources Example 14 2 Using Dyninst as a Stand alone Application Consider the exercise C source file from Example 14 1 Using Dyninst with SystemTap this program prompts the user to enter a starting number and then counts down to 1 calling the print_iteration function for each iteration in order to print the number to standard output Now consider another source file named count C with the following contents include lt stdio h gt include lt fcntl h gt include BPatch h include BPatch_process h include BPatch_function h include BPatch_Vector h include BPatch_thread h include BPatch_point h void usage fprintf stderr Usage count lt process_id gt lt function gt n J Global information for counter BPatch_variableExpr counter NULL void createCounter BPatch_process app BPatch_image appImage int zero 0 counter app gt malloc appImage gt findType int counter gt writeValue amp zero bool interceptfunc BPatch_process app BPatch_i
60. The use of this Help section is detailed in the Red Hat Enterprise Linux Developer Guide linked below Online Documentation Red Hat Enterprise Linux 6 Developer Guide and Red Hat Enterprise Linux 7 Developer Guide The Developer Guides for Red Hat Enterprise Linux 6 and 7 provide more information on Eclipse including a description of the user interface overview of available development toolkits or instructions on how to use it to build RPM packages a User Guide See Also Section A 1 Changes in Eclipse provides a comprehensive list of features and improvements over the Eclipse development environment included in Red Hat Enterprise Linux 6 and the previous release of Red Hat Developer Toolset Chapter 1 Red Hat Developer Toolset provides an overview of Red Hat Developer Toolset and more information on how to install it on your system Chapter 3 GNU Compiler Collection GCC provides information on how to compile programs written in C C and Fortran on the command line 20 Part Ill Development Tools Part Ill Development Tools 21 Chapter 3 GNU Compiler Collection GCC The GNU Compiler Collection commonly abbreviated GCC is a portable compiler suite with support for a wide selection of programming languages Red Hat Developer Toolset is distributed with GCC 4 9 2 This version is more recent than the version included in Red Hat Enterprise Linux and provides a number of bug fixes and enhancements
61. Toolset version of binutils provides these features The objcopy utility now supports wildcards for section names in command line options The AVX 512 512 bit Advanced Vector Extensions are now supported For a full list of changes and features introduced in this release see Appendix A Changes in Version 1 3 Compatibility Red Hat Developer Toolset 3 1 is available for Red Hat Enterprise Linux 6 and 7 for 64 bit Intel and AMD architectures Figure 1 1 Red Hat Developer Toolset 3 1 Compatibility Matrix illustrates the support for binaries built with Red Hat Developer Toolset on a certain version of Red Hat Enterprise Linux when those binaries are run on various other versions of this system For ABI compatibility information see Section B 2 1 5 ABI Compatibility User Guide Runs on 6 5 EUS 6 5 6 5 EUS v Built 6 6 X with S44 7 0 x 71 X AAR AM v 65 X v x x x x KK q X Unsupported V Supported Figure 1 1 Red Hat Developer Toolset 3 1 Compatibility Matrix 1 4 Getting Access to Red Hat Developer Toolset Red Hat Developer Toolsetis an offering that is distributed as a part of the Red Hat Software Collections content set which is available to customers with Red Hat Enterprise Linux 6 and 7 subscriptions listed at https access redhat com solutions 472793 Depending on the subscription management service with which you registered your Red Hat Enterprise Linux system you can either enab
62. acters from one string to another while overwriting the terminating null byte of the second string and adding a new one atits end It returns a pointer to the new string wmemcpy The wide character equivalent of the memcpy function that copies n wide characters from one array to another and returns a pointer to the second array wmempcpy The wide character equivalent of the mempcpy function that copies n wide characters from one array to another and returns a pointer to the byte following the last written wide character wcscpy The wide character equivalent of the strcpy function that copies a wide character string from one array to another and returns a pointer to the second array wcsncpy The wide character equivalent of the strncpy function that copies a maximum of n wide characters from one array to another and returns a pointer to the second string Function Description wcscat The wide character equivalent of the strcat function that appends one wide character string to another while overwriting the terminating null byte of the second string and adding a new one atits end It returns a pointer to the new string wcsncat The wide character equivalent of the strncat function that appends a maximum of n wide characters from one array to another while overwriting the terminating null byte of the second wide character string and adding a new one atits end It returns a pointer to the new string 10 1 Installing memstomp In
63. allation Guide and Red Hat Enterprise Linux 7 Installation Guide The Installation Guides for Red Hat Enterprise Linux 6 an 7 explain how to obtain install and update the system Red Hat Enterprise Linux 6 Deployment Guide The Deployment Guide tor Red Hat Enterprise Linux 6 documents relevant information regarding the deployment configuration and administration of Red Hat Enterprise Linux 6 Red Hat Enterprise Linux 7 System Administrator s Guide The System Administrator s Guide tor Red Hat Enterprise Linux 7 documents relevant information regarding the deployment configuration and administration of Red Hat Enterprise Linux 7 79 User Guide Chapter 16 Contacting Global Support Services Unless you have a Self Support subscription when both the Red Hat Documentation website and Customer Portal fail to provide the answers to your questions you can contact Global Support Services GSS 16 1 Gathering Required Information Several items of information should be gathered before contacting GSS Background Information Ensure you have the following background information at hand before calling GSS Hardware type make and model on which the productruns Software version Latest upgrades Any recent changes to the system An explanation of the problem and the symptoms Any messages or significant information aboutthe issue If you ever forget your Red Hatlogin information it can be recovered at Diagnostics The
64. aluation and show breakpoint condition evaluation commands have been added These commands allow you to control whether breakpoint conditions are evaluated by GDB the host option or by gdbserver the target option The default option auto chooses the most efficient available mode New set dprintf style gdb call agentand show dprintf style commands have been added These commands allow you to control the way in which a dynamic printf is performed the gdb option requests a GDB printf command call causes dprintf to calla function in the inferior and agent requests that the target agent such as gdbserver does the printing New set dprintf function expression show dprintf function set dprintf channel expression and show dprintf channel commands have been added These commands allow you to set the function and optional first argument to the call when using the call style of dynamic printf New set disconnected dprintf on off and show disconnected dprintf commands have been added These commands allow you to control whether agent style dynamic printfs continue to be in effect after GDB disconnects New set print type methods on off and show print type methods commands have been added These commands allow you to control whether method declarations are displayed by the ptype command This functionality is enabled by default New set print type typedefs on off and show print type typedefs commands have been added These commands allow you t
65. and or other countries MySQL is a registered trademark of MySQL AB in the United States the European Union and other countries Node js is an official trademark of Joyent Red Hat Software Collections is not formally related to or endorsed by the official Joyent Node js open source or commercial project The OpenStack Word Mark and OpenStack Logo are either registered trademarks service marks or trademarks service marks of the OpenStack Foundation in the United States and other countries and are used with the OpenStack Foundation s permission We are not affiliated with endorsed or sponsored by the OpenStack Foundation or the OpenStack community All other trademarks are the property of their respective owners Abstract Red Hat Developer Toolsetis a Red Hat offering for developers on the Red Hat Enterprise Linux platform The Red Hat Developer Toolset User Guide provides an overview of this product explains how to invoke and use the Red Hat Developer Toolset versions of the tools and links to resources with more in depth information User Guide Part I Introduction Chapter 1 Red Hat Developer Toolset 1 1 About Red Hat Developer Toolset Red Hat Developer Toolset is a Red Hat offering for developers on the Red Hat Enterprise Linux platform It provides a complete set of development and performance analysis tools that can be installed and used on multiple versions of Red Hat Enterprise Linux Executables built with the
66. aries and libraries built with Red Hat Developer Toolset 3 1 GCC using Cilk features on supported Red Hat Enterprise Linux releases that do not contain Libcilkrts install the Libcilkrts so shared library from Red Hat Developer Toolset 3 1 with such binaries or libraries Example 3 1 Compiling a C Program on the Command Line Consider a source file named hello c with the following contents include lt stdio h gt int main int argc char argv printf Hello World n return o To compile this source code on the command line by using the gcc compiler from Red Hat Developer Toolset type 23 scl enable devtoolset 3 gcc o hello hello c This creates a new binary file called hello in the current working directory 3 1 3 Running a C Program When gcc compiles a program it creates an executable binary file To run this program on the command line change to the directory with the executable file and type file_name Example 3 2 Running aC Program on the Command Line Assuming that you have successfully compiled mE hello binary file as shown in Example 3 1 hello Hello World 3 2 GNU C Compiler 3 2 1 Installing the C Compiler In Red Hat Developer Toolset the GNU C compiler is provided by the devtoolset 3 gcc c package and is automatically installed with the devtoolset 3 toolchain package as described in Section 1 5 Installing Red Hat Developer Toolset 3 2
67. art has been added When producing ELF output this symbol points to the ELF file header and nearby program headers in the program s memory image B 3 1 1 2 Compatibility Changes The following compatibility changes have been made since the release of binutils included in Red Hat Enterprise Linux 6 6 The copy dt needed entries command line option is no longer enabled by default Instead no copy dt needed entries is now the default option Evaluation of linker script expressions has been significantly improved Note that this can negatively affect scripts that rely on undocumented behavior of the old expression evaluation B 3 1 2 GNU Assembler B 3 1 2 1 New Features The following features have been added since the release of binutils included in Red Hat Enterprise Linux 6 6 The GNU Assembler no longer requires double ampersands in macros Anew compress debug sections command line option has been added to enable compression of DWARF debug information sections in the relocatable output file Compressed debug sections are currently supported by the readelf objdump and gold tools but not by ld Supportfor bundle_align_mode bundle_lock and bundle_unlock directives for x86 targets has been added On x86 architectures the GNU Assembler now allows rep bsf rep bsr and rep ret syntax B 3 1 3 Other Binary Tools B 3 1 3 1 New Features The following features have been added since the release of binutils in
68. at Developer Toolset Container Images Starting with Red Hat Developer Toolset 3 1 Dockerfiles are available for selected Red Hat Developer Toolset components Dockerfiles are text documents that contain instructions for automated building of docker formatted container images The resulting container images can be used to run Red Hat Developer Toolset components inside virtual software containers thus isolating them from the host system and allowing for their rapid deployment This section describes how to obtain Red Hat Developer Toolset Dockerfiles how to use them to build docker formatted container images and howto run Red Hat Developer Toolset components using the resulting container images Red Hat Developer Toolset 3 1 is shipped with the following Dockerfiles 11 User Guide devtoolset 3 dyninst devtoolset 3 elfutils devtoolset 3 oprofile devtoolset 3 systemtap only for Red Hat Enterprise Linux 7 devtoolset 3 toolchain devtoolset 3 valgrind devtoolset 3 only for Red Hat Enterprise Linux 7 The docker package which contains the Docker daemon command line tool and other necessary components for building and using docker formatted container images is currently only available for the Server variant of the Red Hat Enterprise Linux 7 product Red Hat Developer Toolset Dockerfiles are distributed for Red Hat Enterprise Linux 6 as well but the images built using them can only be deployed on Red Hat Enterprise Linux 7 Server
69. ation is recompiled the module and all files which directly use such symbols have to be recompiled as well This change only affects the following kind of module symbols Procedure pointers Note that C interoperable function pointers type c_funptr are not affected nor are procedure pointer components Deferred length character strings B 2 1 4 x86 specific Improvements New Instructions GCC 4 8 has added support for the Intel FXSR XSAVE and XSAVEOPT instructions Corresponding intrinsics and built in functions can now be enabled by using the mfxsr mxsave and mxsaveopt command line options respectively In addition support for the RDSEED ADCX ADOX and PREFETCHW instructions has been added and can be enabled by using the mrdseed madx and mprfchw command line options 107 User Guide New Built in Functions to Detect Run time CPU Type and ISA Anew built in function builtin_cpu_is has been added to detect if the run time CPU is ofa particular type This function accepts one string literal argument with the CPU name and returns a positive integer on a match and zero otherwise For example __ bui Ltin_cpu_is westmere returns a positive integer if the run time CPU is an Intel Core i7 Westmere processor For a complete list of valid CPU names see the user manual A new built in function builtin_cpu_supports has been added to detect if the run time CPU supports a particular ISA feature This function ac
70. automatically executed when the stap utility is executed with the b command line option stap report Gathers important information about the system for the purpose of reporting a bug in SystemTap stap server A compile server which listens for requests from stap clients 11 1 Installing SystemTap In Red Hat Developer Toolset SystemTap is provided by the devtoolset 3 systemtap package and is The Red Hat Developer Toolset version of SystemTap is available for both Red Hat Enterprise Linux 6 and Red Hat Enterprise Linux 7 but some new features are only offered by the Red Hat Developer Toolset version of SystemTap for Red Hat Enterprise Linux 7 See In order to place instrumentation into the Linux kernel SystemTap may also require installation of additional packages with debugging information To determine which packages to install run the stap prep utility as follows scl enable devtoolset 3 stap prep 62 Chapter 11 SystemT ap Note that if you execute this command as the root user the utility automatically offers the packages for installation For more information on how to install these packages on your system see the Red Hat Enterprise Linux 6 SystemTap Beginners Guide or the Red Hat Enterprise Linux 7 SystemTap 11 2 Using SystemTap To execute any of the tools that are part of SystemTap type the following at a shell prompt scl enable devtoolset 3 tool option See Table 11 1 Tools Distributed with SystemTap fo
71. available subscription this command displays its name unique identifier expiration date and other details related to your subscription The pool ID is listed on a line beginning with Pool ID For a complete list of subscriptions that provide access to Red Hat Developer Toolset see 2 Attach the appropriate subscription to your system by running the following command as root subscription manager attach pool pool_id Replace pool_id with the pool ID you determined in the previous step To verify the list of subscriptions your system has currently attached at any time run as root subscription manager list consumed 3 Determine the exact name of the Red Hat Software Collections repository To do so type the following ata shell promptas root to retrieve repository metadata and to display a list of available Yum repositories subscription manager repos list The repository names depend on the specific version of Red Hat Enterprise Linux you are using and are in the following format rhel variant rhscl version rpms rhel variant rhscl version debug rpms rhel variant rhscl version source rpms In addition certain packages such as devtoolset 3 gcc plugin devel depend on packages that are only available in the Optional channel The repository names with these packages use the following format rhel version variant optional rpms rhel version variant optional debug rpms rhel version variant optional source rpms For both the
72. been introduced The dwarf_peel_type function has been added for handling qualified types It is also used by dwarf_aggregate_size to provide the sizes of qualified types The dwarf_getmacros function now serves both the debug_macro and debug_macinfo section data transparently The following new interfaces are available for a more generalized inspection of macros and their parameters dwarf_getmacros_off dwarf_macro_getsrcfiles dwarf_macro_getparamcnt and dwarf_macro_param The following new attributes have been added to dwarf h DW_AT_GNU_deleted DW_AT_noreturn DW_LANG_C11 DW_LANG_C_plus_plus_11 and DW_LANG_C_plus_plus_14 A 4 Changes in GDB Red Hat Developer Toolset 3 1 is distributed with GDB 7 8 2 which provides a number of bug fixes and improvements over the Red Hat Enterprise Linux system versions and the version included in the previous release of Red Hat Developer Toolset Below is a comprehensive list of new features in this release A 4 1 Changes Since Red Hat Developer Toolset 3 0 The following features have been added since the release of GDB in Red Hat Developer Toolset 3 0 Anew command add auto load scripts directory directory has been added It adds entries to the list of directories from which automatically loaded scripts are loaded The gdb jit reader h header file is now installed in the include directory so thatit can be used for writing readers for parsing custom debugging information formats See
73. bject associated with a PC value The gdb Symtab_and_line object now has an additional attribute Last This attribute holds the end of the address range occupied by the code for the current source line Users can now create vectors by using the gdb Type vector method The atexit register method is now supported Users can now pretty print types by using the Python API In addition to Python 2 4 and later GDB now also supports Python 3 Anew class gdb Architecture has been added This class exposes the internal representation of the architecture in the Python API A new method Frame architecture has been added This method can be used to return the gdb Architecture object corresponding to the frame s architecture Frame filters and frame decorators have been added Compatibility Changes A new command info auto load has been added and can be used to display the status of various automatically loaded files The info auto load gdb scripts command lists automatically loaded canned sequences of commands info auto load python scripts displays the status of automatically loaded Python scripts info auto load local gdbinit displays whether a local gdbini t file in the current working directory is loaded and info auto load libthread db displays whether the inferior specific thread debugging shared library is loaded Annandiv R Phaannonc in Jarcinn 2 A Appen dix B Chan ges in version o U New commands set auto load and sh
74. cepts one string literal argument with the ISA feature and returns a positive integer on a match and Zero otherwise For example __builtin_cpu_supports ssse3 returns a positive integer if the run time CPU supports SSSE3 instructions For a complete list of valid ISA names see the user manual Important If these built in functions are called before any static constructors are invoked such as IFUNC initialization then the CPU detection initialization must be explicitly run using this newly provided built in function builtin_cpu_init The initialization needs to be done only once For example the following is sample invocation inside an IFUNC initializer static void some_ifunc_resolver void void __builtin_cpu_init if __builtin_cpu_is amdfam10h if __builtin_cpu_supports popcnt Function Multiversioning Function multiversioning allows the programmer to specify multiple versions of the same function each of which is specialized for a particular variant of a given target At runtime the appropriate version is automatically executed depending upon the target where the execution takes place For example consider the following code fragment _ attribute__ target default int foo return 0 _ attribute__ target sse4 2 int foo return 1 __attribute__ target arch atom int foo return 2 When the function foo is executed the result returned depends upon the ar
75. chitecture where the details New RTM and HLE Intrinsics Support for the Intel RTM and HLE intrinsics built in functions and code generation has been added and can be enabled by using the mrtm and mhle command line options This is done via intrinsics for Restricted Transactional Memory RTM and extensions to the memory model for Hardware Lock Elision HLE For HLE two new flags can be used to mark a lock as using hardware elision _ATOMIC_HLE_ ACQUIRE 108 Appendix B Changes in Version 3 0 Starts lock elision on a lock variable The memory model in use mustbe __ ATOMIC ACQUIRE or stronger __ATOMIC_HLE_RELEASE Ends lock elision on a lock variable The memory model must be __ ATOMIC_RELEASE or stronger For example consider the following code fragment while __atomic_exchange_n amp lockvar 1 __ATOMIC_ACQUIRE __ATOMIC_HLE_ACQUIRE _mm_pause work with the acquired lock __atomic_clear amp lockvar _ATOMIC_RELEASE __ATOMIC_HLE_RELEASE The new intrinsics that support Restricted Transactional Memory are unsigned _xbegin void Attempts to start a transaction If it succeeds this function returns _XBEGIN_STARTED otherwise it returns a status value indicating why the transaction could not be started void _xend void Commits the current transaction When no transaction is active this function causes a fault All memory side effects of the transactions become visible to other threads in a
76. cluded in Red Hat Enterprise Linux 6 6 The readelf and objdump tools can now display the contents of the debug macro sections New dwarf startand dwarf end command line options have been added to the readelf and objdump tools These options are used by the new Emacs mode see the dwarf mode el file Anew interleave width command line option has been added to the objcopy tool to allow the use of the interleave to copy a range of bytes from the input to the output Anew dyn syms command line option has been added to the readel f tool This option can be used to dump dynamic symbol table Anew tool elfedit has been added to binutils This tool can be used to directly manipulate ELF format binaries Anew command line option addresses or a for short has been added to the addr2line tool This option can be used to display addresses before function and source file names Anew command line option pretty print or p for short has been added to the addr21line tool This option can be used to produce human readable output Supportfordwz m optimized debug information has been added The devtoolset 2 binutils devel package now provides the demang1Le h header file B 3 2 Changes Since Red Hat Developer Toolset 2 1 and Red Hat Enterprise Linux 7 0 The following bugs have been fixed and features added since the release of binutils in Red Hat Developer Toolset 2 1 and Red Hat Enterprise Linux 7 0 The detection of
77. cludes an enhanced task focused interface and task editing a new Jenkins Hudson connector enhanced Bugzilla and Trac connectors EPUB authoring tools various improvements to the Bugzilla connector A new EGit plug in has been added This plug in includes an Eclipse Team provider based on JGit a Git implementation written entirely in Java and adds support for the Git revision control system to the Eclipse user interface by introducing the History and Synchronize views Compare and Quick Diff menu items and various wizards to make it easier for developers to use this plug in Further updates of the EGit plug in have introduced the following improvements support for Mylin links in the History view Git Staging view and Commit dialog window improved Gerrit integration a significantly enhanced Git Staging view an enhanced command line tool jgit several performance improvements New GCov integration has been added to allow the user to visualize GCov output in both summarized form and in file editors As well graphing capabilities for the data have been added New GProf integration has been added to allow the user to view profiling information such as execution time and call graphs As well graphing capabilities for the data have been added Anew SystemTap integration plug in has been added This plug in includes an editor for the stp files with the autocomplete feature the Probe view with a list of probes that are available
78. cpp option may be required as well The finit real command line option now supports snan as a valid value This allows you to initialize REAL and COMPLEX variables with a signaling NaN not a number and requires you to enable trapping for example by using the f f pe trap command line option Note that compile time optimizations may turn a signaling NaN into a quiet NaN Anew command line option fcheck has been added This option accepts the following arguments Annandiy PR Chanqaac in Varcinn 2 N Appen dix B Chan ges in version o U The fcheck bounds option is equivalent to the fbounds check command line option The fcheck array temps option is equivalent to the fcheck array temporaries command line option The fcheck do option checks for invalid modification of loop iteration variables The fcheck recursive option checks for recursive calls to subroutines or functions that are not marked as recursive The fcheck pointer option performs pointer association checks in calls but does not handle undefined pointers nor pointers in expressions The fcheck all option enables all of the above options Anew command line option fno protect parens has been added This option allows the compiler to reorder REAL and COMPLEX expressions with no regard to parentheses When OpenMP s WORKSHARE is used array assignments and WHERE will now be run in parallel More Fortran 2003 and Fortran 2008 mathematical functions can now b
79. d bpatch waitForStatusChange return 0 Note that a client application is expected to destroy all Bpatch objects before any of the Dyninst library destructors are called Otherwise the mutator might terminate unexpectedly with a segmentation fault To work around this problem set the BPatch object of the mutator as a local variable in the main function Or if you need to use BPatch as a global variable manually detach all the mutatee processes before the mutator exits 74 Crynanant nar 146 Aunin ct Chapter 14 Dyninst This program accepts a process ID and a function name as command line arguments and then prints the total number of times the function was called during the execution of the process You can use the following Makefile to build these two files DTS opt rh devtoolset 3 root CXXFLAGS g I DTS usr include dyninst LBITS shell getconf LONG_BIT ifeq LBITS 64 DYNINSTLIBS DTS usr 1lib64 dyninst else DYNINSTLIBS DTS usr lib dyninst endif PHONY all all count exercise count count C g CXXFLAGS count C I usr include dyninst c g CXXFLAGS count o L DYNINSTLIBS ldyninstAPI o count exercise exercise C g CXXFLAGS exercise C o exercise PHONY clean clean rm rf 0 count exercise To compile the two programs on the command line using the g compiler from Red Hat Developer Toolset run the make utility as follows scl enable devtoolset 3 make
80. d param changed has been added This async record reports that a command parameter has changed A new async record traceframe changed has been added This async record reports that a trace frame has been changed by using the tfind command New async records tsv created tsv deleted and tsv modified have been added These async records report that a trace state variable has been created deleted or modified New async records record started and record stopped have been added These async records report that a process record has been started or stopped A new async record memory changed has been added This async record reports that the memory has changed When the source is requested the data disassemble command now includes a new fullname field containing an absolute path to the source file name The fullname filed is now always present along with the file field This field is included even if GDB cannotfind the file A new optional parameter COUNT has been added to the data write memory bytes command This parameter can be used to allow pattern filling of memory areas The response to breakpoint commands and breakpoint async records now includes a new installed field This field reports the current state of each non pending tracepoint location when the tracepoint is installed the value of this field is y otherwise the value is n The output of the trace status command now includes a new trace file field This
81. d Dwfl_Frame and the following functions dwfl_attach_state dwfl_pid dwfl_thread_dwfl dwfl_thread_tid dwfl_frame_thread dwfl_thread_state_registers dwfl_thread_state_register_pc dwfl_getthread_frames dwfl_getthreads dwfl_thread_getframes and dwfl_frame_pc The eu addr2line utility has a new option x or symbol sections to show the section in which an address was found A new utility eu stack has been added that uses the new unwinder for processes and cores A new backend has been added The unwinder now supports the ARM 64 bit architecture which allows for manipulation of ELF and DWARF files specific for ARM 64 bit The CVE 2014 0172 has been fixed The bug was caused by an integer overflow that led to a added before calling malloc to uncompress data B 4 2 Changes Since Red Hat Enterprise Linux 7 0 The following features have been added since the release of elfutils 0 158 in Red Hat Enterprise Linux 7 0 The eu stack utility has two new options Anew option d or debugname has been added for looking up DWARF debugging information names for frame addresses Anew option 1 or inlines has been added for showing inlined frames using DWARF debugging information The libdwelf library has been improved in a number of ways Anew header file Libdwelf h has been added for Libdw so low level DWARF or ELF helper functions New functions have been added dwelf_elf_gnu_debuglink dwelf_dwarf_gnu_debugaltlink
82. d Hat Developer Toolset 3 1 contain more information Red Hat Enterprise Linux 6 Developer Guide and Red Hat Enterprise Linux 7 Developer Guide The Developer Guides for Red Hat Enterprise Linux 6 and 7 provide more information on the Eclipse IDE libraries and runtime support compiling and building debugging and profiling on these systems 13 User Guide Red Hat Enterprise Linux 6 Installation Guide and Red Hat Enterprise Linux 7 Installation Guide The nstallation Guides for Red Hat Enterprise Linux 6 an 7 explain how to obtain install and update the system Red Hat Enterprise Linux 6 Deployment Guide The Deployment Guide tor Red Hat Enterprise Linux 6 documents relevant information regarding the deployment configuration and administration of Red Hat Enterprise Linux 6 Red Hat Enterprise Linux 7 System Administrator s Guide The System Administrator s Guide tor Red Hat Enterprise Linux 7 documents relevant information regarding the deployment configuration and administration of Red Hat Enterprise Linux 7 Get Started with Docker Formatted Container Images on Red Hat Systems The Knowledgebase article contains a comprehensive overview of information about building and using docker formatted container images on Red Hat Developer Toolset 7 and Red Hat Enterprise Linux Atomic See Also Appendix A Changes in Version 3 1 provides a list of changes and improvements over the version of the GNU Compil
83. d its features is beyond the scope of this book For more information see the resources listed below Installed Documentation The devtoolset 3 dyninst doc package installs the following documents in the opt rh devtoolset 3 root usr share doc devtoolset 3 dyninst doc 8 2 0 directory Dyninst Programmer s Guide A detailed description of the Dyninst API is stored in the DyninstAPL pdf file DynC API Programmer s Guide An introduction to DynC API is stored in the dynC _ AP I pdf file ParseAPI Programmer s Guide An introduction to the ParseAPI is stored in the ParseAPI pdf file PatchAPI Programmer s Guide An introduction to PatchAPI is stored in the P atchAP I pdf file ProcControlAPI Programmer s Guide A detailed description of ProcControlAPI is stored in the ProcControlAPI pdf file StackwalkerAPI Programmer s Guide A detailed description of StackwalkerAPI is stored in the stackwalker pdf file SymtabAPI Programmer s Guide An introduction to SymtabAPI is stored in the SymtabAPL pdf file InstructionAPI Reference Manual A detailed description of the InstructionAPI is stored in the InstructionAPI pdf file Online Documentation Dyninst Home Page The project home page provides links to additional documentation and related publications Chapter 14 Dyninst Red Hat Enterprise Linux 6 SystemTap Beginners Guide The SystemTap Beginners Guide for Red Hat Enterprise Linux 6 provide
84. d line option Floating point calculations on x86 targets and in strict C99 mode are now compiled by GCC with a stricter standard conformance This might result in those calculations executing significantly slower It can be disabled using fexcess precision fast B 2 1 6 Debugging Compatibility GCC now generates DWARF debugging information that uses more or newer DWARF features than previously GDB contained in Red Hat Developer Toolset can handle these features but versions of GDB older than 7 0 cannot GCC can be restricted to only generate debugging information with older DWARF features by using the gdwarf 2 gstrict dwarf or gdwarf 3 gstrict dwarf options the latter are handled partially by versions of GDB older than 7 0 Many tools such as Valgrind SystemTap or third party debuggers utilize debugging information Itis suggested to use the gdwarf 2 gstrict dwarf options with those tools Use of Link time Optimization with debug generation is not yet Supported in gcc 4 7 and 4 8 and so use of the flto and the g options together is unsupported in Red Hat Developer Toolset B 2 1 7 Other Compatibility GCC is now more strict when parsing command line options and both gcc and g report an error when invalid command line options are used In particular when only linking and not compiling code earlier versions of GCC ignored all options starting with For example options accepted by the linker such as as needed and
85. d to conform to N3638 C 1y lambda capture initializers no longer trigger a warning when the std c 1y argument is used Parenthesized and brace enclosed initializers are now also accepted C 1y variable length arrays VLA are now supported as well as initializers and lambda capture by reference Note that in C 1y mode g complains about VLA usage not permitted by the draft standard The C 1y deprecated attribute is now supported for marking classes and functions as deprecated Amessage for diagnosis can be included in the attribute C 1y digit separators are now supported In order to ensure better code legibility long numeric literals can be subdivided using the single quote character For example int i 123 456 789 C 1y generic polymorphic lambdas are now supported They serve as functional objects that O1 increment any type For example auto incr auto x return x 1 Improved C 11 and C 14 Support in the C Runtime Library The C runtime library C 11 support has been improved The lt regex gt header is now supported Experimental support for the upcoming ISO C standard C 14 has been added New Undefined Behavior Detector UndefinedBehaviorSanitizer ubsan a fast undefined behavior detector has been added and can be enabled using the fsanitize undefined command line option Various computations will be instrumented to detect undefined behavior at run time UndefinedBe
86. d with Dyninst 8 2 which provides a number of bug fixes and feature enhancements over the version included in Red Hat Enterprise Linux and the previous version of Red Hat Developer Toolset Below is a comprehensive list of new features in this release B 11 1 Changes Since Red Hat Developer Toolset 2 1 and Red Hat Enterprise Linux 7 0 A number of bugs have been fixed In addition to that the following features have been added since the release of Dyninst in Red Hat Developer Toolset 2 1 and Red Hat Enterprise Linux 7 0 The ProcControl library has been improved to provide callbacks whenever a syscall monitored thread enters or exits a system call The SymtabAPI library has been improved to support access to inline functions Checks are now performed and errors returned in case the instrumentation requires traps but the user has disabled them The generation of XMM registers save and restore has been improved and function call snippets have been optimized as a result Block level instrumentation performance in shared code has been improved Whenever possible checks are now performed on parameter and return value snippets Symbol visibility is now properly controlled so that only public Dyninst functions and variables are exposed to users User Guide Appendix C Revision History Revision 0 0 25 Thu 04 June 2015 Robert Kr tk Update to reflect RHSCL 2 0 GA Revision 0 0 23 Thu 23 Apr 2015 Robert Kr tk Release of Red Ha
87. der file You can set a breakpoint by using the new probe pstap or probe stap options and inspect the probe arguments by using the new _probe_arg family of convenience variables The symbol reloading option has been deleted gdbserver now supports STDIO connections for example gdb target remote ssh myhost gdbserver hello GDB is now able to print flag enums In a flag enum all enumerator values have no bits in common when pairwise AND ed When GDB prints a value whose type is a flag enum GDB shows all the constants for example forenumE ONE 1 TWO 2 gdb print enum E 3 1 ONE TWO The file name part of a linespec now matches trailing components of a source file name For example break gcc expr c 1000 now sets a breakpoint in the build gcc expr c file but notin build libcpp expr c The info proc and generate core file commands now work on remote targets connected to gdbserver The command info catch has been removed The Ada specific catch exception and catch assert commands now accept conditions at the end of the command Theinfo static tracepoint marker command now works on native targets with an in process agent GDB can now set breakpoints on inline functions User Guide The gdb_index section has been updated to include symbols for inline functions By default GDB now ignores older gdb_index sections until their gdb_index sections can be recreated The new command set use deprecated
88. dge with RDRND FSGSBASE and F16C march core avx2 Optimization for a next generation processor from Intel with AVX2 FMA BMI BMI2 and LZCNT march bdver2 and mtune bdver2 Optimization for AMD Opteron processors code named Piledriver march btver1 and mtune btver1 Optimization for AMD family 14 processors code named Bobcat march bdveri1 and mtune bdver1 Optimization for AMD family 15h processors code named Bulldozer Support for various processor specific intrinsics and instructions is now available through the Table B 2 Support for Processor specific Intrinsics and Instructions Option Description mavx2 Support for Intel AVX2 intrinsics built in functions and code generation mbmi2 Support for Intel BMI2 intrinsics built in functions and code generation mlzcnt Implementation and automatic generation of _ builtin clz using the Lzcnt instruction mfma Support for Intel FMA3 intrinsics and code generation mfsgsbase Enables the generation of new segment register read write instructions through dedicated built ins mrdrnd Support for the Intel rdrnd instruction mf16c Support for two additional AVX vector conversion instructions mtbm Support for TBM Trailing Bit Manipulation built in functions and code generation mbmi Support for AMD s BMI Bit Manipulation built in functions and code generation mcrc32 Support for crc32 intrinsics mmovbe Enables the use of the movbe instruction to implement
89. e To display the manual page for the version included in Red Hat Developer Toolset type scl enable devtoolset 3 man staprun SystemTap Tapset Reference Manual HTML documentation on the most common tapset definitions is located at opt rh devtoolset 3 root usr share doc devtoolset 3 systemtap client 2 5 index html Online Documentation Red Hat Enterprise Linux 6 SystemTap Beginners Guide and Red Hat Enterprise Linux and 7 provide an introduction to SystemTap and its usage Red Hat Enterprise Linux 6 SystemTap Tapset Reference and Red Hat Enterprise Linux l and 7 provides further details about SystemTap The SystemTap Documentation The official SystemTap documentation provides further documentation on SystemTap as well as numerous examples of SystemTap scripts See Also Section A 5 Changes in SystemTap provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of SystemTap and the version distributed in the previous release of Red Hat Developer Toolset Chapter 1 Red Hat Developer Toolset provides an overview of Red Hat Developer Toolset and more information on how to install it on your system Chapter 12 Valgrind explains how to use Valgrind to profile applications and detect memory errors and memory management problems such as the use of uninitialized memory improper allocation and freeing of memory and the use of improper arguments in system call
90. e list of documents that are included in the devtoolset 3 dyninst doc package see Section 14 3 Additional Resources For detailed instructions on aon to install optional packages 14 2 Using Dyninst 14 2 1 Using Dyninst with SystemTap To use Dyninst along with SystemTap to allow non root users to instrument user space executables run the stap command with the dyninst or runtime dyninst command line option This tells stap to translate a SystemTap script into C code that uses the Dyninst library compile this C code into a shared library and then load the shared library and run the script Note that when executed like this the stap command also requires the c or x command line option to be specified To use the Dyninst runtime to instrument an executable file type the following ata shell prompt scl enable devtoolset 3 stap dyninst c command option argument Similarly to use the Dyninst runtime to instrument a user s process type scl enable devtoolset 3 stap dyninst x process_id option argument User Guide See Chapter 11 SystemTap for more information aboutthe Red Hat Developer Toolset version of Example 14 1 Using Dyninst with SystemTap Consider a source file named exercise C thathas the following contents include lt stdio h gt void print_iteration int value printf Iteration number d n value J int main int argc char argv int i printf Ente
91. e option now only displays warnings when a conversion leads to information loss and anew command line option Wconversion extra has been added to display warnings about other conversions The Wconversion option is now enabled with wall Anew command line option Wunused dummy argument has been added This option can be used to display warnings about unused dummy arguments and is now enabled with wall Note that the Wunused variable option previously also warned about unused dummy arguments The COMMON default padding has been changed Previously the padding was added before a variable Nowit is added after a variable to increase the compatibility with other vendors as well as to help to obtain the correct output in some cases Note that this behavior is in contrast with the behavior of the falign commons option GNU Fortran no longer links against the Libg fortranbegin library The MAIN__ assembler symbol is the actual Fortran main program and is invoked by the main function which is now generated and putin the same object file as MAIN__ Note that the Libgfortranbegin library is still present for backward compatibility Some internal names used in the assembler or object file have changed for symbols declared in the specification part of a module If an affected module or a file using it via use association is recompiled the module and all files which directly use such symbols have to be recompiled as well This change only af
92. e used as initialization expressions The GCC compiler directive now enables support for some extended attributes such as STDCALL B 2 1 3 2 Compatibility Changes The Ofast command line option now automatically enables the fno protect parens and fstack arrays flags Front end optimizations can now be disabled by the fno frontend optimize option and selected by the ffrontend optimize option The former is essentially only desirable if invalid Fortran source code needs to be compiled for example when functions as compared to subroutines have side effects or to work around compiler bugs The GFORTRAN_USE_STDERR environment variable has been removed and GNU Fortran now always prints error messages to standard error The fdump core command line option and the GFORTRAN_ERROR_DUMPCORE environment variable have been removed When encountering a serious error GNU Fortran now always aborts the execution of the program The fbacktrace command line option is now enabled by default When a fatal error occurs GNU Fortran now attempts to print a backtrace to standard error before aborting the execution of the program To disable this behavior use the fno backtrace option GNU Fortran no longer supports the use of the M command line option to generate Makefile dependencies for the module path To perform this operation use the J option instead To significantly reduce the number of warnings the Wconversion command lin
93. each output At present only time stamps are supported debug format timestamps Time stamps can also be turned on with the monitor set debug format timestamps command in GDB General Changes The Fission DWP file format in version 2 is now supported To use Fission supply the gsplit dwarf option to gcc to generate split DWARF files at compile time This option must be used in conjunction with the c option which disables linking because Fission cannot be used when information about the Fission project Access to Intel MPX registers is now supported Support for Intel AVX 512 registers has been added that is support for displaying and modifying the following Intel AVX 512 registers zmm0 zmm31 kO0 k7 xmm16 xmm31 and ymm16 ymm31 Anew convenience function _1svoid expression has been added The function returns 1 if the type of the evaluated expression is void In other cases it returns 0 When displaying the values of registers for which the debugging information shows that they have not been saved in the frame and there is no place to retrieve them from callee saved or call clobbered registers the lt not saved gt message is now consistently printed A new formatter z has been added When printing and examining memory this formatter causes the value to be displayed as a hexadecimal zero padded on the left to the size of the type Target assigned range stepping with remote targets is now su
94. eatures over the version included in Red Hat Enterprise Linux and the previous version of Red Hat Developer Toolset B 2 1 Changes Since Red Hat Enterprise Linux 6 6 The following features have been added since the release of GCC in Red Hat Enterprise Linux 6 6 B 2 1 1 Status and Features B 2 1 1 1 C 11 GCC 4 7 and later provides experimental support for building applications compliant with C 11 using the std c 11 or std gnu 11 command line options However there is no guarantee for compatibility between C 11 code compiled by different versions of the compiler Refer to The C runtime library Libstdc supports a majority of the C 11 features However there is no or only partial support for some features such as certain properties on type traits or regular defined behavior Support for C 11 exception_ptr and future requires changes to the exception handling runtime in the system libstdc package These changes will be distributed through the normal Z stream channel Application of all Red Hat Enterprise Linux errata may be required to see correct runtime functionality when using these features B 2 1 1 2 C11 GCC 4 7 and later provides experimental support for some of the features from the C11 revision of the ISO C standard and in addition to the previous now deprecated std c1x and std gnu1x command line options gcc now accepts std c11 and std gnu11 Note that since this support is experimental it may change
95. ed Hat Developer Toolset 3 1 A 1 Changes in Eclipse Red Hat Developer Toolset 3 1 is distributed with Eclipse 4 4 2 and other plugins from the Luna release train SR2 Service Release 2 which provides a number of bug fixes and feature enhancements over the version included in Red Hat Enterprise Linux and the previous version of Red Hat Developer Toolset This section contains a comprehensive list of new features and compatibility changes in this release For details on how to use these new features refer to the built in Eclipse documentation A 1 1 Changes Since Red Hat Developer Toolset 3 0 The Eclipse Platform has been updated from version 4 4 0 to 4 4 2 As this is a service release it contains over 100 bug fixes and optimizations including The stability of SWT on GTK3 on Red Hat Enterprise Linux 7 has been improved Support for Java 8 has been improved both in the compiler and editing capabilities Eclipse CDT C C Development Tooling has been updated from version 8 5 to 8 6 This release includes a number of enhancements including the following New filtering options have been added to the Search view A new preference option has been added for defining the style of the Include Guard code The autocomplete and content assist functions have been improved Refactoring has been improved to properly update include statements Support has been added for Save actions similarly to JDT The GDB information provided duri
96. ed to remove a symbol file added using the add symbo 1 file command The file to remove can be identified by its file name remove symbol file FILENAME Or by an address that lies within the boundaries of this symbol file in memory In that case use the a option remove symbol file a ADDRESS A new command info exceptions has been added It can be used to display the list of Ada exceptions defined in the program being debugged Optionally a regular expression can be supplied to limit the list of displayed exceptions info exceptions REGEXP If provided only the exceptions whose names match REGEXP are listed The following new pairs of commands make it possible to change settings and show their values set debug symfile off on Controls the displaying of debugging information regarding the reading of symbol files and symbol tables within those files The show debug symfile command shows the value of this setting set print raw frame arguments off on Controls the displaying of frame arguments in raw mode disregarding any defined pretty printers The show print raw frame arguments command shows the value of this setting set remote trace status packet off on auto Controls the use of the remote protocol qTStatus packet The packet is used to ask the remote stub whether a trace experiment is currently running The show remote trace status packet command shows the value of this setting set range stepping off on Co
97. emory management problems such as the use of uninitialized memory improper allocation and freeing of memory and the use of improper arguments in system calls Chapter 14 Dyninst documents how to use the Dyninst library to instrument a user space executable 70 Chap 14 Dyni Chapter 14 Dyninst The Dyninst library provides an application programming interface API for instrumenting and working with user space executables during their execution It can be used to insert code into a running program change certain subroutine calls or even remove them from the program It serves asa valuable debugging and performance monitoring tool The Dyninst API is also commonly used along with SystemTap to allow non root users to instrument user space executables Red Hat Developer Toolset is distributed with Dyninst 8 2 1 14 1 Installing Dyninst In Red Hat Developer Toolset the Dyninst library is provided by the devtoolset 3 dyninst package and is automatically installed with devtoolset 3 perftools as described in Section 1 5 Installing Red Hat Collection od by the devtoolset 3 toolchain package If you intend to write a custom instrumentation for binaries install the relevant header files by running the following command as root yum install devtoolset 3 dyninst devel You can also install API documentation for this library by typing the following ata shell prompt as root yum install devtoolset 3 dyninst doc For a complet
98. emstomp utility to identify calls to library functions with overlapping memory regions that are not allowed by various standards Chapter 11 SystemTap provides an introduction to SystemTap and explains how to use it to monitor the activities ofa running system Chapter 13 OProfile explains how to use OProfile to determine which sections of code consume the greatest amount of CPU time and why Chapter 14 Dyninst documents how to use the Dyninst library to instrument a user space executable 67 Chapter 13 OProfile OProfile is a low overhead system wide profiler that uses the performance monitoring hardware on the processor to retrieve information about the kernel and executables on the system such as when memory is referenced the number of level 2 cache L2 requests and the number of hardware interrupts received It consists of a configuration utility a daemon for collecting data and a number of tools that can be used to transform the data into a human readable form For a complete list of tools that are distributed with the Red Hat Developer Toolset version of OProfile see Table 13 1 Tools Distributed with OProfile for Red Hat Developer Toolset OProfile profiles an application without adding any instrumentation by recording the details of every nth event This allows it to consume fewer resources than Valgrind but it also causes its samples to be less precise Unlike Valgrind which only collects data for a single p
99. en improved Dyninst now hides the Linux gate so 1and linux vdso so 1 Virtual Dynamic Shared Objects VSDO from link maps Appendix B Changes in Version 3 0 The sections below document features and compatibility changes introduced in Red Hat Developer Toolset 3 0 B 1 Changes in Eclipse Red Hat Developer Toolset 3 0 is distributed with Eclipse 4 4 and other plugins from the Luna release train which provides a number of bug fixes and feature enhancements over the version included in Red Hat Enterprise Linux and the previous version of Red Hat Developer Toolset This section contains a comprehensive list of new features and compatibility changes in this release For details on how to use these new features refer to the built in Eclipse documentation B 1 1 Changes Since Red Hat Enterprise Linux 6 6 The following features have been added since the release of Eclipse in Red Hat Enterprise Linux 6 6 The Eclipse C C Development Toolkit CDT has been updated This update includes a greatly enhanced indexer both in terms of capabilities and speed improved GNU Debugger integration support for GNU Debugger s pretty printing multi process debugging project less debugging enhanced refactoring code checking capabilities an improved and more polished user interface fixes related to the organization of include statements Mylyn a set of task and application life cycle management plug ins has been updated This update in
100. ent in the form of a regular expression The commands set remotebaud and show remotebaud are no longer supported Use set serial baud to set the baud rate for remote serial I O and show serial baud to display the set rate The record function call history command has been modified in a number of ways The command now supports a new modifier c for indenting function names based on their call stack depth The fields for the 1 and 1 modifiers have been reordered The source line range is now prefixed with at The instruction range is now prefixed with inst Both ranges are now printed as lt fro m gt lt to gt to allow copy and paste to the record instruction history and list commands B 6 Changes in strace Red Hat Developer Toolset 3 0 is distributed with strace 4 8 which provides a number of bug fixes and feature enhancements over the version included in Red Hat Enterprise Linux and the previous version of Red Hat Developer Toolset Below is a comprehensive list of new features in this release B 6 1 Changes Since Red Hat Enterprise Linux 6 6 The following features have been added since the release of strace in Red Hat Enterprise Linux 6 6 L i eo ro mes Yee Ce A new command line option y has been added This option can be used to print file descriptor paths Anew command line option P has been added This option can be used to filter system calls based on the file descriptor paths A new command line
101. ep has been added This pragma notifies the compiler that no loop carried dependencies exist that would prevent a concurrent execution with SIMD Single Instruction Multiple Data of consecutive iterations of the loop that follows the pragma Mudflap Tool Removed The Mudflap runtime checking tool was removed from the GCC suite and is no longer supported B 2 2 2 C and C Changes ISO C11 Support Support for C11 has been improved ISO C11 atomics the _ Atomic type specifier and qualifier and the lt stdatomic h gt header are now supported ISO C11 generic selections the _Generic keyword are now supported ISO C11 thread local storage the _Thread_local keyword is now supported New _ auto_type Extension forthe C Language A new C extension auto in GNU C auto_type has been added It provides a subset of the functionality of C 11 Support for OpenMP 4 0 The C and C compilers now support the OpenMP 4 0 specification Anew option fopenmp simd has been added that can be used to enable OpenMP SIMD Single Instruction Multiple Data directives The vectorization cost model for loops annotated with OpenMP and Cilk SIMD directives can be altered using the new fsimd cost model option The cost models available are unlimited dynamic and cheap Improved C 14 Support The g compiler offers improved support for various features of the C standard The C 1y return type deduction for normal functions has been update
102. eparate output file with the dwo file extension and allows the build system to avoid linking files with debugging information In order to be useful this option requires a debugger capable of reading dwo files such as the version of GDB included in Red Hat Developer Toolset 3 0 elfutils SystemTap and Valgrind do not support the dwo files B 2 1 10 Caveats Aggressive Loop Optimizations The loop optimizer of GCC has been improved to use language constraints in order to derive bounds for the number of iterations of a loop The bounds are then used as a guide to loop unrolling peeling and loop exit test optimizations The optimizations assume that the loop code does not invoke undefined behavior by for example causing signed integer overflows or making out of bound array accesses For example consider the following code fragment unsigned int foo unsigned int data_data 128 for int fd 0 fd lt 128 F fd 113 data_data fd fd 0x02000001 error return data_data 0 When the value of the fd variable is 64 or above the fd 0x02000001 operation overflows which is invalid in both C and C for signed integers In the example above GCC may generate incorrect code or enter an infinite loop To fix this error use the appropriate casts when converting between signed and unsigned types to avoid overflows for instance data_data fd uint32_t fd 0x02000001U ok If necessary this
103. er Collection and GNU Debugger in the previous version of Red Hat Developer Toolset Appendix B Changes in Version 3 0 provides a comprehensive list of changes and improvements over the Red Hat Enterprise Linux system versions of the GNU Compiler Collection GNU Debugger and binutils as well as information about the language ABI and debugging compatibility 14 Part II Integrated Development Environments Part Il Integrated Development Environments 15 User Guide Chapter 2 Eclipse Eclipse is a powerful development environment that provides tools for each phase of the development process It integrates a variety of disparate tools into a unified environment to create a rich development experience provides a fully configurable user interface and features a pluggable architecture that allows for an extension in a variety of ways For instance the Valgrind plug in allows programmers to perform memory profiling otherwise performed on the command line through the Eclipse user interface C C Hello World C src Hello World C cpp Eclipse Platform o File Edit Source Refactor Navigate Search Project Run Window Help Pv amp B v A vA gyv evev v Ov Q vav BEB VY 4 fe T 4 v pl vita v Quick Access E Resource amp Java Eg lt r c Outline 2 E e Hello World C cpp X Make Targe X B El R o Name 0 0 1 Hello cpp amp gt amp Author Version v amp
104. es a new plain text file called fibonacci log in the current working directory 8 2 2 Tracing Selected System Calls To trace only a selected set of system calls run the strace utility with the e command line option scl enable devtoolset 3 strace e expression program argument Replace expression with a comma separated list of system calls to trace or any of the keywords listed in Table 8 1 Commonly Used Values of the e Option For a detailed description of all available values see the strace 1 manual page Table 8 1 Commonly Used Values of the e Option Value Description file System calls that accept a file name as an argument process System calls that are related to process management network System calls that are related to networking signal System calls that are related to signal management ipc System calls that are related to inter process communication IPC desc System calls that are related to file descriptors Example 8 2 Tracing Selected System Calls Consider the employee file from Example 10 1 Using memstomp To run the strace utility on this executable file and trace only the mmap and munmap system calls type scl enable devtoolset 3 strace e mmap munmap employee mmap NULL 4096 PROT_READ PROT_WRITE MAP_PRIVATE MAP_ANONYMOUS 1 0 0x7f896c744000 mmap NULL 61239 PROT_READ MAP_PRIVATE 3 0 0x7f896c735000 mmap 0x3146a00000 3745960 PROT_READ PROT_EXEC MAP_P
105. es in version o U The naming of native targets has been unified and they are now all called native To reflect this change the target child command has been replaced by target native Target names feature in the output of the following commands help target info target info files and maint print target stack The following commands have been modified The unlimited literal value can now be used for options that interpret the O or 1 values as unlimited The set debug symtab create debugging command has been changed to accept a verbosity level O provides no debugging information 1 provides basic debugging output and values of 2 or greater provide a more verbose output The compare sections command now works with all targets In previous versions it was limited to the remote target The target native command can now be used to explicitly connect to the native target which overrides the setting ofthe set auto connect native target command The ranges given as arguments to the record function call history and record instruction history commands are now inclusive The record instruction history command now starts counting instructions at one This also affects the instruction ranges reported by the record function call history command when given the i modifier The tsave command now supports a new option ctf to save trace data in the Common Trace Format CTF The maintenance print objfiles command now accepts an optional argum
106. es over the version included in Red Hat Enterprise Linux and the previous version of Red Hat Developer Toolset Below is a comprehensive list of new features in this release B 9 1 Changes Since Red Hat Developer Toolset 2 1 and Red Hat Enterprise Linux 6 6 The following features have been added since the release of Valgrind 3 8 1 included in Red Hat Developer Toolset 2 1 and Red Hat Enterprise Linux 6 6 B 9 1 1 Changes in Tools Memcheck Anew command line option partial loads ok argument has been added The option accepts the yes or no arguments The default is no The option can be used to significantly reduce the number of false error reports when handling vectorised code New command line options show leak kinds argument and errors for leak kinds argument have been added Both options accept a comma separated list of the following arguments definite indirect possible reachable as well as all or none The default setting for both options is equivalent to passing the definite and possible arguments The options allow you to exercise a finer control over the leak checker by specifying the kinds of leaks that are to be shown or suppressed in a full leak search and that are to count as errors ina full leak search Optionally you can also specify the kinds of leaks to Suppress directly in the suppressions file using the match leak kinds line Note that the generated suppressions files now include this line by default
107. esources A detailed description of Valgrind and its features is beyond the scope of this book For more information see the resources listed below Installed Documentation valgrind 1 The manual page for the valgrind utility provides detailed information on how to use Valgrind To display the manual page for the version included in Red Hat Developer Toolset type scl enable devtoolset 3 man valgrind 66 Chapter 12 Valgrind Valgrind Documentation HTML documentation for Valgrind is located at opt rh devtoolset 3 root usr share doc devtoolset 3 valgrind 3 9 0 htm1l index html Online Documentation Red Hat Enterprise Linux 6 Developer Guide and Red Hat Enterprise Linux 7 Developer Guide The Developer Guides for Red Hat Enterprise Linux 6 and 7 provide more information about Valgrind and its Eclipse plug in Red Hat Enterprise Linux 6 Performance Tuning Guide Red Hat Enterprise Linux 7 Performance more detailed information about using Valgrind to profile applications See Also Section A 6 Changes in Valgrind provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of Valgrind and the version distributed in the previous release of Red Hat Developer Toolset Chapter 1 Red Hat Developer Toolset provides an overview of Red Hat Developer Toolset and more information on how to install iton your system Chapter 10 memstomp documents how to use the m
108. essions that can be transformed into constants by the compiler but are in fact not constant expressions as defined by ISO C this may cause warnings or errors Ill formed redeclarations of library functions are no longer accepted by the compiler In particular a function with a signature similar to the built in declaration of a library function for example abort or memcpy must be declared with extern C to be considered as a redeclaration otherwise it is ill formed Duplicate Member Consider the following struct declaration struct A int a union struct int a 1 1 Previously this declaration used to be diagnosed just by the C compiler now itis also diagnosed by the C compiler Because of the anonymous unions and structs there is ambiguity about what a actually refers to and one of the fields therefore needs to be renamed B 2 1 2 2 C Header Dependency Changes lt iostream gt lt string gt and other STL headers that previously included lt unistd h gt as an implementation detail to get some feature macros for gthr h purposes no longer do so because itwas a C standard violation This can result in diagnostic output similar to the following error truncate was not declared in this scope error sleep was not declared in this scope error pipe was not declared in this scope error there are no arguments to offsetof that depend on a template parameter so a declaration of o
109. execute the next three lines of code type gdb step 3 13 b sum This allows you to verify the current value of the sum variable before it is assigned to b gdb print sum 3 2 7 9 Additional Resources Ae 46 Chapter 7 GNU Debugger GDB A detailed description of the GNU Debugger and all its features is beyond the scope of this book For more information see the resources listed below Online Documentation Red Hat Enterprise Linux 6 Developer Guide and Red Hat Enterprise Linux 7 Developer Guide The Developer Guides for Red Hat Enterprise Linux 6 and 7 provide more information on the GNU Debugger and debugging GDB Documentation The official GDB documentation includes the GDB User Manual and other reference material See Also Section A 4 Changes in GDB provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of the GNU Debugger and the version distributed in the previous release of Red Hat Developer Toolset Chapter 1 Red Hat Developer Toolset provides an overview of Red Hat Developer Toolset and more information on how to install iton your system Chapter 2 Eclipse provides a general introduction to the Eclipse development environment and describes how to use it with the tools from Red Hat Developer Toolset Chapter 3 GNU Compiler Collection GCC provides further information on how to compile programs written in C C and Fort
110. export dynamic are not accepted by gcc and g anymore and should now be directed to the linker using W1 as needed or W1 export dynamic if that is intended Because of the new link time optimization feature see Section B 2 1 1 5 Link time Optimization command line option is not accepted anymore B 2 1 8 General Improvements and Changes New Local Register Allocator GCC 4 8 features a new Local Register Allocator LRA which replaces the 26 year old reload pass and improves the quality of generated code The new local register allocator is meant to be simpler easier to debug and does a better job of register allocation AddressSanitizer 111 A fast memory error detector called AddressSanitizer has been added and can be enabled by using the fsanitize address command line option It augments memory access instructions in order to detect use after free and out of bound accesses to objects on the heap ThreadSanitizer A fast data race detector called ThreadSanitizer has been added in GCC 4 8 The option to enable this feature is fSanitize thread Compiling Extremely Large Functions Many scalability bottlenecks have been removed from GCC optimization passes As a consequence itis now possible to compile extremely large functions with smaller memory consumption in less time New Og Optimization Level A new general optimization level Og has been introduced This optimization level addresses the need for
111. f data types This allows for declaring for example that a function expects a char parameter but that parameter should be formatted as an enum or in hexadecimal It is now also possible to express zero terminated NUL NULL arrays Unwinder support has been added so that the user can request a stack trace to be shown for each traced call Support for tracing IFUNC symbols has been added These are special symbols that resolve to one of possible implementations after the first call is made Itrace now re seats related breakpoints after an IFUNC call finishes It also Supports tracing the related IRELATIVE PLT slots B 8 Changes in SystemTap Red Hat Developer Toolset 3 0 is distributed with SystemTap 2 5 which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version and the version included in the previous release of Red Hat Developer Toolset Below is a list of new features in this release B 8 1 Changes Since Red Hat Developer Toolset 2 1 The following features have been added since the release of SystemTap included in Red Hat Developer Toolset 2 1 The tapset library no longer signals certain types of errors by returning dummy values Instead fully fledged SystemTap errors are generated that can be caught using the try catch construct Alternatively other tapset functions may be used to return user specified dummy values The dyninst backend which can be enabled by pas
112. fast compilation and a superior debugging experience while providing a reasonable level of runtime performance Overall the development experience should be better than the default optimization level 00 Caret Diagnostic Messages The diagnostic messages of GCC which display a line of source code now also show a caret that indicates the column where the problem was detected For example fred cc 4 15 fatal error foo No such file or directory include lt foo gt A compilation terminated New fira hoist pressure Option Anew command line option fira hoist pressure has been added This option uses the register allocator to help decide when it is worthwhile to move expressions out of loops It can reduce the size of the compiler code but it slows down the compiler This option is enabled by default at Os New fopt info Option Anew command line option fopt info has been added This option controls printing information about the effects of particular optimization passes and takes the following form fopt info info file_name The info part of the option controls what is printed Replace it with optimized to print information when optimization takes place missed to print information when optimization does not take place note to print more verbose information or optall to print everything Replace file_name with the name of the file in which you want the information to be written If you omit this part of the opti
113. faster than this tool and therefore serves as a convenient alternative to it Red Hat Developer Toolset is distributed with memstomp 0 1 5 Table 10 1 Function Calls Inspected by memstomp Function Description memcpy Copies n bytes from one memory area to another and returns a pointer to the second memory area memccpy Copies a maximum of n bytes from one memory area to another and stops when a certain character is found It either returns a pointer to the byte following the last written byte or NULL if the given character is not found mempcpy Copies n bytes from one memory area to another and returns a pointer to the byte following the last written byte strcpy Copies a string from one memory area to another and returns a pointer to the second string stpcpy Copies a string from one memory area to another and returns a pointer to the terminating null byte of the second string strncpy Copies a maximum of n characters from one string to another and returns a pointer to the second string stpncpy Copies a maximum of n characters from one string to another It either returns a pointer to the terminating null byte of the second string or ifthe string is not null terminated a pointer to the byte following the last written byte strcat Appends one string to another while overwriting the terminating null byte of the second string and adding a new one atits end It returns a pointer to the new string strncat Appends a maximum ofn char
114. fects the following kind of module symbols Procedure pointers Note that C interoperable function pointers type c_funptr are not affected nor are procedure pointer components Deferred length character strings B 2 1 3 3 Fortran 2003 Features Improved but still experimental support for polymorphism between libraries and programs and for complicated inheritance patterns Generic interface names which have the same name as derived types are now supported which allows the creation of constructor functions Note that Fortran does not support static constructor functions only default initialization or an explicit structure constructor initialization are available Automatic re allocation In intrinsic assignments to allocatable variables the left hand side will be automatically allocated if unallocated or reallocated if the shape or type parameter is different To avoid the small performance penalty you can use a instead ofa for arrays and character strings or disable the feature using std f95 or fno realloc tLhs Experimental support of the ASSOCIATE construct has been added In pointer assignments it is now possible to specify the lower bounds of the pointer and fora rank 1 or a simply contiguous data target to remap the bounds Deferred type parameter For scalar allocatable and pointer variables the character length can now be deferred Namelist variables with allocatable attribute pointer attrib
115. fer in their scope applicability and complexity of runtime support C 11 Types and GCC Built ins for Atomic Memory Access C 11 has support for atomic types Access to memory locations of this type is atomic and appears as one indivisible access even when other threads access the same memory location concurrently The atomicity is limited to a single read or write access or one of the other atomic operations supported by such types for example two subsequent operations executed on a variable of atomic type are each atomic separately but do not form one joint atomic operation An atomic type is declared as atomic lt T gt where T is the non atomic base type and must be trivially copyable for example atomic lt int gt is an atomic integer GCC does not yet support any base type T but only those that can be accessed atomically with the atomic instructions offered by the target architecture This is nota significant limitation in practice given that atomics are primarily designed to expose hardware primitives in an architecture independent fashion pointers and integrals that are not larger than a machine word on the target are supported as base types Using base types that are not yet supported results in link time errors The code generated for operations on atomic types including the memory orders implements the semantics specified in the C 11 standard However support for the C 11 memory model is still experimental and for example
116. fff13afc265 src 0x7fff13afc269 bytes 21 overlap for employee 14887 22 0 strcpy 22 0 strcpy 22 0 _Exit 22 0 strcat employee c 26 main 22 0 __libc_start_main 22 0 _start John john example comDoe O1 O User Guide 10 3 Additional Resources A detailed description of memstomp and its features is beyond the scope of this book For more information see the resources listed below Installed Documentation Se 60 memstomp 1 The manual page for the memstomp utility provides detailed information about its usage To display the manual page for the version included in Red Hat Developer Toolset type scl enable devtoolset 3 man memstomp e Also Chapter 1 Red Hat Developer Toolset provides an overview of Red Hat Developer Toolset and more information on how to install iton your system Chapter 7 GNU Debugger GDB provides information on how to debug programs written in C C and Fortran Chapter 8 strace documents how to use the strace utility to monitor system calls that a program uses and signals it receives Chapter 12 Valgrind explains how to use Valgrind to profile applications and detect memory errors and memory management problems such as the use of uninitialized memory improper allocation and freeing of memory and the use of improper arguments in system calls Part V Performance Monitoring Tools Part V Performance Monitoring Tools 61 User Guide Chapter
117. ffsetof must be available To fix this add the following line early in the source or header files that need it include lt unistd h gt Many of the standard C library include files have been edited to no longer include lt cstddef gt to get namespace std scoped versions of Ssize_tand ptrdiff_t As such C programs that used the macros NULL or of fsetof without including lt cstddef gt will no longer compile The diagnostic produced is similar to the following error ptrdiff_t does not name a type error size_t has not been declared error NULL was not declared in this scope error there are no arguments to offsetof that depend on a template parameter so a declaration of offsetof must be available To fix this issue add the following line include lt cstddef gt Name Lookup Changes G no longer performs an extra unqualified lookup thatit incorrectly performed in the past Instead itimplements the two phase lookup rules correctly and an unqualified name used in a template must have an appropriate declaration that 1 is either in scope at the point of the template s definition or 2 can be found by argument dependent lookup at the point of instantiation Code that incorrectly depends on a second unqualified lookup at the point of instantiation Such as finding functions declared after the template or in dependent bases will result in compile time errors In some cases the diagnostics provided by
118. field is only present when examining a trace file and contains the name of this file New Commands The following new commands have been added New set use deprecated index sections on off and show use deprecated index sections on off commands have been added These commands allow you to control the use of deprecated gdb_index sections New catch load and catch unload commands have been added These commands allow you to stop execution of a debugged program when a shared library is loaded or unloaded Anew enable count command has been added This command allows you to auto disable a breakpoint after several hits Anew info vtbl command has been added This command allows you to show the virtual method tables for C and Java objects Anew explore command has been added It Supports two subcommands explore value and explore type and allows you to recursively explore values and types of expressions Note that this command is only available with Python enabled GDB Anewdprintf location format args command has been added This command allows you to create a dynamic printf type breakpoint which performs a printf like operation and then resumes program execution New set print symbol and show print symbol commands have been added These commands allow you to control whether GDB attempts to display the symbol if any that corresponds to addresses it prints This functionality is enabled by default but you can restore the previous
119. files See Table 5 1 Jools Included in elfutils Developer Toolset version of elfutils Red Hat Developer Toolset is distributed with elfutils 0 161 This version is more recent than the version included in Red Hat Enterprise Linux and the previous release of Red Hat Developer Toolset and provides numerous bug fixes and enhancements Table 5 1 Tools Included in elfutils for Red Hat Developer Toolset Name Description eu addr2line Translates addresses into file names and line numbers eu ar Creates modifies and extracts files from archives eu elfcmp Compares relevant parts of two ELF files for equality eu elflint Verifies that ELF files are compliant with the generic ABI gABI and processor specific supplement ABI psABI specification eu findtextrel Locates the source of text relocations in files eu make debug Creates an offline archive for debugging archive eu nm Lists symbols from object files eu objdump Displays information from object files eu ranlib Generates an index to the contents of an archive to make access to this archive faster eu readelf Displays information about ELF files eu size Lists section sizes of object or archive files eu stack A new utility for unwinding processes and cores eu strings Displays printable character sequences in files eu strip Discards all symbols from object files eu unstrip Combines stripped files with separate symbols and debug information 5 1 Installing elfut
120. following new options have been added Anew command line option 1x or init command has been added This option acts like x or command but is executed before loading the debugged program Anew command line option iex or init eval command has been added This option acts like ex or eval command but is executed before loading the debugged program Anew command line option nh has been added This option allows you to disable automatic loading ofthe gdbinit file without disabling other initialization files C Language Support The following changes have been made to the C language support When debugging a template instantiation parameters of the template are now putin scope Python Scripting Support The following changes have been made to the Python scripting support The register_pretty_printer function in module gdb printing now takes an optional replace argument Themaint set python print stack on off command has been deprecated and will be deleted in GDB 7 5 The new command set python print stack none full message has replaced it A prompt substitution hook prompt_hook is now available to the Python API Anew Python module gdb prompt has been added to the GDB Python modules library Python commands and convenience functions located in data_directory python gdb command and data_directory python gdb function are now automatically loaded on GDB start up Blocks now provide four new attr
121. g g I opt rh devtoolset 3 root usr include dyninst count C c g g I opt rh devtoolset 3 root usr include dyninst count o L opt rh devtoolset 3 root usr lib64 dyninst ldyninstAPI o count g g I opt rh devtoolset 3 root usr include dyninst exercise C o exercise This creates new binary files called exercise and count in the current working directory In one shell session execute the exercise binary file as follows and wait for itto prompt you to enter the starting number exercise Enter the starting number Do not enter this number Instead start another shell session and type the following at its prompt to set the DYNINSTAPI_RT_LIB environment variable and execute the count binary file export DYNINSTAPI_RT_LIB opt rh devtoolset 3 root usr 1ib64 dyninst libdyninstAPI_RT so count pidof exercise print_iteration Finding function print_iteration OK Instrumenting function print_iteration OK Waiting for process 8607 to exit Now switch back to the first shell session and enter the starting number as requested by the exercise program For example Enter the starting number 5 Iteration number 5 Iteration number Iteration number Iteration number Iteration number BMWA When the exercise program terminates the count program displays the number of times the print_iteration function was executed Function executed 5 times 14 3 Additional Resources A detailed description of Dyninst an
122. g type the following ata shell prompt scl enable devtoolset 3 gdb file_name This starts the gdb debugger in interactive mode and displays the default prompt gdb To quit the debugging session and return to the shell prompt run the following command at any time quit Note that you can execute any command using the sc1 utility causing itto be run with the Red Hat Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent This allows you to run a shell session with Red Hat Developer Toolset gdb as default scl enable devtoolset 3 bash User Guide To verify the version of gdb you are using at any point type the following at a shell prompt which gdb Red Hat Developer Toolset s gdb executable path will begin with opt Alternatively you can use the following command to confirm that the version number matches that for Red Hat Developer Toolset gdb gdb v Example 7 3 Running the gdb Utility on the fibonacci Binary File Assuming that you have successfully compiled the Fibonacci binary file as shown in Example 7 1 Compiling a C Program With Debugging Information you can start debugging it with gdb by typing the following ata shell prompt scl enable devtoolset 3 gdb fibonacci GNU gdb GDB Red Hat Enterprise Linux 7 4 50 20120120 43 e16 Copyright C 2012 Free Software Foundation Inc License GPLv3 GNU GPL version 3 or later lt http gnu org licenses gpl html gt
123. g tools SystemTap Valgrind OProfile Dyninst devtoolset 3 toolchain Development and debugging GCC GDB binutils elfutils dwz tools memstomp strace Itrace To install any of these meta packages type the following ata shell promptas root yum install package_name Replace package_name with a space separated list of meta packages you want to install For example to install only the Eclipse development environment and packages that depend on it type as root yum install devtoolset 3 ide User Guide Alternatively you can choose to install all available components as described in Section 1 5 1 Installing All Available Components 1 5 3 Installing Optional Packages Red Hat Developer Toolset is distributed with a number of optional packages that are not installed by default To list all Red Hat Developer Toolset packages that are available to you but not installed on your system type the following command ata shell prompt yum list available devtoolset 3 To install any of these optional packages run as root yum install package_name Replace package_name with a space separated list of packages that you want to install For example to install the devtoolset 3 gdb gdbserver and devtoolset 3 gdb doc packages type yum install devtoolset 3 gdb gdbserver devtoolset 3 gdb doc 1 5 4 Installing Debugging Information To install debugging information for any of the Red Hat Developer Toolset packages make sure that
124. har p foobar _ TIME_ In C 03 the __ TIME__ macro expands to some string literal and is concatenated with the other one In C 11 __ TIME__ is not expanded and instead operator __TIME__ is being looked up which results in a warning like error unable to find string literal operator operator TIME__ This applies to any string literal followed without white space by some macro To fix this add some white space between the string literal and the macro name Taking the Address of Temporary Consider the following code 99 SEruct S A S Int i y void bar S void foo bar amp S J Previously an attempt to compile this code produced a warning message now it fails with an error This can be fixed by adding a variable and passing the address of this variable instead of the temporary The fpermissive compiler flag turns compile time errors into warnings and can be used as a temporary workaround Miscellaneous G now sets the predefined macro __cplusplus to the correct value 199 711L for C 98 03 and 20110 3L for C 11 G now properly re uses stack space allocated for temporary objects when their lifetime ends which can significantly lower stack consumption for some C functions As a result of this some code with undefined behavior will now break When an extern declaration within a function does not match a declaration in the enclosing context G now properly declares the name within t
125. hat has virtual functions and a non virtual destructor is destroyed by using delete This is unsafe to do because the pointer might refer to a base class that does not have a virtual destructor The warning is enabled by wall and by a new command line option Wdelete non virtual dtor New Wc 11 compat and Wc 0x compat options are now available These options cause GCC to display a warning about C constructs whose meaning differs between ISO C 1998 and ISO C 2011 such as identifiers in ISO C 1998 that are keywords in ISO C 2011 This warning is enabled by Wall and enables the Wnarrowing option B 2 1 3 Fortran B 2 1 3 1 New Features Anew compile flag fstack arrays has been added This flag causes all local arrays to be put on stack memory which can significantly improve the performance of some programs Note that programs that use very large local arrays may require you to extend your runtime limits for stack memory Compile time has been significantly improved For example the improvement may be noticeable when working with programs that use large array constructors To improve code generation and diagnostics the fwhole file compile flag is now enabled by default and can be used with a newly supported fwhole program flag To disable it use the deprecated fno whole file flag Anew command line option Mis now supported Similarly to gcc this option allows you to generate Makefile dependencies Note that the
126. hat times out no longer results in false errors B 9 1 2 Other Changes The space required by Valgrind now better corresponds with the expected capabilities of the target Anew command line option num transtab sectors number has been added The option can be used to specify the maximum number of sectors in the translation cache The default number of sectors has been increased to 16 in order to accommodate applications that need to store large amounts of code This improves performance because Valgrind does not need to re translate and re instrument machine code so often The number of memory mapped segments that can be tracked has been increased by a factor of 6 The way Valgrind reads debugging information has been improved Valgrind no longer uses excessive amounts of virtual memory when reading debuginfo from large shared objects Instead of temporarily mapping entire objects for reading Valgrind now uses only a small fixed buffer Anew command line option debuginfo server ipaddress port has been added This option allows you to instruct Valgrind to read debuginfo from objects stored on a different machine and served by a debuginfo server which needs to be accessible on the specified IP address and port Anew command line option allow mismatched debuginfo argument has been added The option accepts the yes and no arguments The default is no Using this option you can instruct Valgrind to ignore inconsistencies between ma
127. haviorSanitizer is currently available for the C and C languages Support for Cilk GCC now adds support for Cilk an extension to the C and C languages for parallel programming It can be enabled using the fcilkplus option The current support implements all features of the version 1 2 ABI with the exception of _C1ilk_ for A new runtime library Libcilkrts is included in this release to support Cilk The Libcilkrts library will be a part of the gcc libraries package in the future Red Hat Enterprise Linux releases but the package is not included in all supported Red Hat Enterprise Linux releases To enable dynamic linkage of binaries and libraries built with Red Hat Developer Toolset 3 1 GCC using Cilk features on supported Red Hat Enterprise Linux releases that do not contain Libcilkrts install the libcilkrts so shared library from Red Hat Developer Toolset 3 1 with such binaries or libraries B 3 Changes in binutils Red Hat Developer Toolset 3 0 is distributed with binutils 2 24 which provides a number of bug fixes and feature enhancements over the version included in Red Hat Enterprise Linux and the previous version of Red Hat Developer Toolset Below is a comprehensive list of new features in this release B 3 1 Changes Since Red Hat Enterprise Linux 6 6 The following features have been added since the release of binutils in Red Hat Enterprise Linux 6 6 The GNU assembler as GNU linker 1d and other binary tools that
128. he namespace of the function rather than the namespace which was open just before the function definition G now implements the proposed resolution of the C standard s core issue 253 Default initialization is allowed if it initializes all subobjects and code that fails to compile can be fixed by providing an initializer such as struct A A struct E A eG 1i te const B b B Access control is now applied to typedef names used in a template which may cause G to reject some ill formed code that was accepted by earlier releases The fno access control option can be used as a temporary workaround until the code is corrected G now implements the C standard s core issue 176 Previously G did not support using the injected class name of a template base class as a type name and lookup of the name found the declaration of the template in the enclosing scope Now lookup of the name finds the injected class name which can be used either as a type or as a template depending on whether or not the name is followed by a template argument list As a result of this change some code that was previously accepted may be ill formed because 1 the injected class name is not accessible because it is from a private base or 2 the injected class name cannot be used as an argument for a template parameter In either of these cases the code can be fixed by adding a nested name specifier to explicitly name the template The first ca
129. ibutes global_block static_block is_ static and is_ global The gdb breakpoint function has been deprecated in favor of gdb breakpoints Anew class gdb FinishBreakpoint is provided Type objects for struct and union types now allow access to the fields using standard Python dictionary mapping methods Anew event gdb new_obj file has been added A new function deep_items has been added to the gdb types module The function gdb Write now accepts an optional keyword stream Parameters can now be sub classed in Python which allows for implementation of the get_set_doc and get_show_doc functions Symbols Symbol Table Symbol Table and Line Object Files Inferior Inferior Thread Blocks and Block Iterator APIs now have an 1S_valid method Breakpoints can now be sub classed in Python which allows for implementation of the stop function that is executed each time the inferior reaches that breakpoint A new function gdb Llookup_global_symbol has been added This function can be used to look up a global symbol GDB values in Python are now callable if the value represents a function Anew module gdb types has been added Anew module gdb printing has been added New commands info pretty printers enable pretty printer and disable pretty printer have been added Anew gdb parameter directories function call is now available A new function gdb newest_frame has been added This function can be used to return the newest
130. ils In Red Hat Developer Toolset elfutils is provided by the devtoolset 3 elfutils package and is automatically installed with devtoolset 3 toolchain as described in Section 1 5 Installing Red Hat Developer Toolset 5 2 Using elfutils To execute any of the tools that are part of elfutils run the command as follows scl enable devtoolset 3 tool option file_name See Table 5 1 Tools Included in elfutils for Red Hat Developer Toolset for a list of tools that are distributed with elfutils For example to use the eu objdump tool to inspect an object file type scl enable devtoolset 3 eu objdump option object_file User Guide Note that you can execute any command using the scl utility causing it to be run with the Red Hat Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent This allows you to run a shell session with Red Hat Developer Toolset binary tools as default scl enable devtoolset 3 bash To verify the version of elfutils you are using at any point type the following ata shell prompt which eu objdump Red Hat Developer Toolset s eu objdump executable path will begin with opt Alternatively you can use the following command to confirm that the version number matches that for Red Hat Developer Toolset eu objdump eu objdump V 5 3 Additional Resources A detailed description of elfutils is beyond the scope of this book For more informatio
131. in Red Hat Developer Toolset to ensure that all features are fully Supported A 9 Lleinan Valavind 65 User Guide 12 4 VONIY VAIYINIU To run any of the Valgrind tools on a program you want to profile type the following ata shell prompt scl enable devtoolset 3 valgrind tool tool program argument See Table 12 1 Tools Distributed with Valgrind for Red Hat Developer Toolset for a list of tools that are distributed with Valgrind The argument of the too1 command line option must be specified in lower case and if this option is omitted Valgrind uses Memcheck by default For example to run Cachegrind on a program to identify the sources of cache misses type scl enable devtoolset 3 valgrind tool cachegrind program argument Note that you can execute any command using the scl utility causing it to be run with the Red Hat Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent This allows you to run a shell session with Red Hat Developer Toolset Valgrind as default scl enable devtoolset 3 bash To verify the version of Valgrind you are using at any point type the following ata shell prompt which valgrind Red Hat Developer Toolset s valgrind executable path will begin with opt Alternatively you can use the following command to confirm that the version number matches that for Red Hat Developer Toolset Valgrind valgrind version 12 3 Additional R
132. in and debuginfo objects Use with caution as Valgrind may not be stable when main and debugging objects do not match Anew command line option merge recursive frame number has been added The option allows you to instruct Valgrind to detect and merge recursive algorithms thus saving memory used to store the recorded stack traces The value supplied to this option determines the complexity of the recursive calls to be merged Anew command line option sigill diagnostics argument has been added This option accepts the yes and no arguments The default is yes Use this option to control whether Valgrind displays a warning when encountering an instruction it is unable to decode or translate In order to be able to run applications that natively require up to 35 GB of memory Valgrind can now use 64 GB of memory on 64 bit targets GDB Server Monitor A new client request VALGRIND_MONITOR_COMMAND has been added to valgrind h Use it to run gdbserver monitor commands from client programs Anew monitor command v info open_fds has been added It provides a list of open file descriptors Note that this is only available if the track fds yes option was passed on Startup Itis now possible to pass an optional message with the v info n_errs_found message monitor command so that a comment can be inserted into process outputs This helps to separate errors reported with different tests Anew monitor command v info exectxt has been
133. incompatibly in future releases Examples for features that are supported are Unicode strings including the predefined macros __STDC_UTF_16__ and __STDC_UTF_32__ nonreturning functions _No return and lt stdnoreturn h gt and alignment support _Alignas Alignof max_align_t and lt stdalign h gt B 2 1 1 3 Parallelism and Concurrency GCC 4 7 and later provides improved support for programming parallel applications 1 The GCC compilers support the OpenMP API specification for parallel programming version 2 The C 11 and C11 standards provide programming abstractions for multi threaded programs The respective standard libraries include programming abstractions for threads and thread related features such as locks condition variables or futures These new versions of the standard also define a memory model that precisely specifies the runtime behavior of a multi threaded program such as the guarantees provided by compilers and the constraints programmers have to pay attention to when writing multi threaded programs Note that support for the memory model is still experimental See below for details For more The rest of this section describes two new GCC features in more detail Both these features make it easier for programmers to handle concurrency such as when multiple threads do not run truly in parallel but instead have to synchronize concurrent access to shared state and both provide atomicity for access to memory but dif
134. kpoints Num Type Disp Enb Address What 1 breakpoint keep y O0x00000000004004e5 in main at Fibonacci c 10 Deleting Existing Breakpoints To delete a breakpoint that is set at a certain line run the following command clear line_number Similarly to delete a breakpoint that is set on a certain function run clear function_name Example 7 7 Deleting an Existing Breakpoint Assuming that you have compiled the Sipe neces file listed in Example 7 1 Compiling a Co atline 7 by running the following command gdb break 7 Breakpoint 2 at 0x4004e3 file fibonacci c line 7 To remove this breakpoint type 44 Chapter 7 GNU Debugger GDB gdb clear 7 Deleted breakpoint 2 7 6 Starting Execution To start an execution of the program you are debugging run the following command run If the program accepts any command line arguments you can provide them as arguments to the run command run argument The execution stops when the first breakpoint if any is reached when an error occurs or when the program terminates Example 7 8 Executing the fibonacci Binary File can execute the fibonacci binary file by running the following command gdb run Starting program home john fibonacci Breakpoint 1 main argc 1 argv 0x7fffffffe4d8 at fibonacci c 10 10 printf ld b 7 7 Displaying Current Values The gdb utility allows you to display the value of almost anything that is relevant to the prog
135. le Red Hat Developer Toolset by using the Red Hat Subscription Management or by using RHN Classic For detailed instructions on how to enable Red Hat Software Collections and thus gain access to Red Hat Developer Toolset using RHN Classic or Red Hat Subscription Management see the respective section below For information on how to register your system with one of these subscription management services see the Red Hat Subscription Management collection of guides Important Red Hat Developer Toolset 3 1 is only compatible with Red Hat Enterprise Linux Server 6 4 and higher and Red Hat Enterprise Linux Workstation 6 5 and higher See Figure 1 1 Red Hat Developer Toolset 3 1 Compatibility Matrix 1 4 1 Using Red Hat Subscription Management If your system is registered with Red Hat Subscription Management complete the following steps to attach a subscription that provides access to the repository for Red Hat Software Collections which includes Red Hat Developer Toolset and then enable that repository q 0 D nd j Pan aAalnanarnav Tan p LD nA ND C AUUAIAN AF Aric 1 XC d Hat Develo pel I ooiset Chapter 1 1 Determine the pool ID of a subscription that provides Red Hat Software Collections and thus also Red Hat Developer Toolset To do so type the following ata shell promptas root to display a list of all subscriptions that are available for your system subscription manager list available For each
136. load python scripts pattern and is no longer classified as a maintenance only command Support for the Guile extension language has been removed The GNU Debugger has been adapted to follow GCC s rules on accessing volatile objects when reading or writing target state during expression evaluation B 5 2 Changes Since Red Hat Developer Toolset 2 1 and Red Hat Enterprise Linux 7 0 The following features have been added since the release of GDB in Red Hat Developer Toolset 2 1 and Red Hat Enterprise Linux 7 0 Python Scripting Support Python scripting support has been improved Support for frame filters and frame decorators has been added Frame filters are Python objects that can be used to manipulate whether frames are visible when GDB prints a backtrace Frame decorators which are sister objects to frame filters are used to customize the printed content of each gdb Frame in commands that execute frame filters Temporary breakpoints which are automatically deleted after they have been hit are now supported through the optional temporary argument to the Breakpoint initializer F o F I j N CO A representation of line tables has been added Line tables map source lines to their executable locations in memory The Linetable function can be used to acquire line table information for a particular symbol table A new attribute parent_type has been added for gdb Field objects gdb Field objects can now be used as subscript
137. lset 3 ltrace e opendirt readdir closedir ls ls gt opendir 3 ls gt readdir 3 61533 J ls gt readdir 3 J Seq Bd a ls gt readdir 3 J 67185100 BUILDROOT ls gt readdir 3 J 202390772 SOURCES ls gt readdir 3 J 60249 SPECS ls gt readdir 3 J 67130110 BUILD ls gt readdir 3 136599168 RPMS ls gt readdir 3 J 202383274 SRPMS ls gt readdir 3 nil ls gt closedir 3 J O BUILD BUILDROOT RPMS SOURCES SPECS SRPMS trr exited status 0 trt For a detailed description of available filter expressions see the Itrace 1 manual page 9 2 3 Displaying Time Stamps To prefix each line of the trace with the exact time of the day in hours minutes and seconds run the ltrace utility with the t command line option scl enable devtoolset 3 ltrace t program argument To also display milliseconds supply the t option twice scl enable devtoolset 3 ltrace tt program argument To prefix each line of the trace with the time required to execute the respective system call use the r command line option scl enable devtoolset 3 ltrace r program argument Example 9 3 Displaying Time Stamps Consider the pwd command To run the 1 trace utility on this program and include time stamps in the output type scl enable devtoolset 3 ltrace tt pwd 13 27 19 631371 __libc_start_main pwd lt unfinished gt
138. lset 3 ltrace o file_name program argument Replace file_name with the name of the file Example 9 1 Redirecting Output to a File Consider a slightly modified version oe fi bonacci file from Example k i P Compiling aC optionally allows you to specify how many members of this sequence to list To run the 1 trace utility on this file and redirect the trace output to fibonacci log type scl enable devtoolset 3 ltrace o fibonacci log fibonacci 20 1123 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181 6765 This creates a new plain text file called fibonacci log in the current working directory 9 2 2 Tracing Selected Library Calls To trace only a selected set of library calls run the Ltrace utility with the e command line option scl enable devtoolset 3 ltrace e expression program argument Replace expression with a chain of rules to specify the library calls to trace The rules can consist of patterns that identify symbol names such as malloc or free and patterns that identify library SONAMEs such as libc so For example to trace call to the malloc and free function but to omit those that are done by the 11bc library use scl enable devtoolset 3 ltrace e malloct free libc so program Example 9 2 Tracing Selected Library Calls Consider the 1s command To run the Ltrace utility on this program and trace only the opendir readdir and closedir function calls type scl enable devtoo
139. m when Ada exceptions are raised Anew command info ada exceptions has been added It provides the equivalent of the new info exceptions command in GDB Anew command gdb set mi async on off has been added It replaces the gdb set target async command which has been deprecated and only serves as an alias to the new command for backward compatibility purposes The gdb set mi async command controls whether MI operates in asynchronous mode If set to on and provided the target supports it MI commands are executed in the background and GDB interprets them while the target is still running New Features in Remote Packets Two remote packets have had their feature set expanded The vCont packet now supports anewr start end action The action instructs the remote stub to perform one step and then continue stepping through the address range specified by the start inclusive and end exclusive parameters The qXfer btrace read packet now supports a new annex delta to read the branch trace incrementally New Features inthe GDB Remote Stub GDBserver GDBserver has had two new features added and one new option Support for target assisted range stepping has been added A new element tvar has been added to the XML in the reply to the qXfer traceframe info read packet It has the id of the collected trace state variables A new option debug format optioni option2 hasbeen added It allows for adding additional text to
140. mage appImage char funcName BPatch_Vector lt BPatch_function gt func 73 User Guide appImage gt findFunction funcName func if func size 0 fprintf stderr Unable to find function to instrument n exit 1 BPatch_Vector lt BPatch_snippet gt incCount BPatch_Vector lt BPatch_point gt points points func 0 gt findPoint BPatch_entry if points size 0 exit 1 BPatch_arithExpr counterPlusOne BPatch_plus counter BPatch_constExpr 1 BPatch_arithExpr addCounter BPatch_assign counter counterPlusOne return app gt insertSnippet addCounter points void printCount BPatch_thread thread BPatch_exitType int val 0 counter gt readValue amp val sizeof int fprintf stderr Function executed d times n val J int main int argc char argv int pid BPatch bpatch if argc 3 usage exit 1 pid atoi argv 1 BPatch_process app bpatch processAttach NULL pid if app exit 1 BPatch_image appImage app gt getImage createCounter app appImage fprintf stderr Finding function s argv 2 BPatch_Vector lt BPatch_function gt countFuncs fprintf stderr OK nInstrumenting function s argv 2 interceptfunc app appImage argv 2 bpatch registerExitCallback printCount fprintf stderr OK nWaiting for process d to exit n pid app gt continueExecution while app gt 1isTerminate
141. mand using the scl utility causing it to be run with the Red Hat Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent This allows you to run a shell session with Red Hat Developer Toolset memstomp as default scl enable devtoolset 3 bash Example 10 1 Using memstomp Chapter 10 memstomp In the current working directory create a source file named employee c with the following contents include lt stdio h gt include lt string h gt define BUFSIZE 80 int main int argc char argv char employee BUFSIZE John Doe john example com char name BUFSIZE 0 char surname BUFSIZE 0 char email size_t length Extract the information 7 memccpy name employee BUFSIZE length strlen name memccpy surname employee length BUFSIZE length strlen surname email employee length Compose the new entry strcat employee surname strcpy employee name strcat employee email Print the result puts employee return 0 Compile this program into a binary file named employee by using the following command scl enable devtoolset 3 gcc rdynamic g o employee employee c To identify erroneous function calls with overlapping memory regions type scl enable devtoolset 3 memstomp debug info employee memstomp 0 1 4 successfully initialized for process employee pid 14887 strcat dest 0x7
142. manual page for the version included in Red Hat Developer Toolset type scl enable devtoolset 3 man ltrace Online Documentation Itrace for RHEL 6 and 7 This article on the Red Hat Developer Blog offers additional in depth information including practical examples on how to use Itrace for application debugging See Also Section B 7 Changes in Itrace provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux 6 6 version of Itrace Chapter 1 Red Hat Developer Toolset provides an overview of Red Hat Developer Toolset and more information on how to install iton your system Chapter 8 strace provides information on how to trace program system calls using the strace C and Eorann Chapter 10 memstomp documents how to use the memstomp utility to identify calls to library functions with overlapping memory regions that are not allowed by various standards 56 Chapter 10 memstomp memstomp is a command line tool that can be used to identify function calls with overlapping memory regions in situations when such an overlap is not permitted by various standards It intercepts calls to the library functions listed in Table 10 1 Function Calls Inspected by memstomp and for each memory overlap it displays a detailed backtrace to help you debug the problem Similarly to Valgrind the memstomp utility inspects applications without the need to recompile them However itis much
143. math is enabled by Ofast GCC can now inform users about cases in which code generation might be improved by adding attributes such as const pure and noreturn to functions declared in header files Use the Wsuggest attribute const pure noreturn command line option to enable this Assembler code can now make use of a goto feature that allows for jumps to labels in C code B 2 1 2 Language Compatibility In this section we describe the compatibility between the Red Hat Developer Toolset compilers and the Red Hat Enterprise Linux system compilers at the programming language level for example differences in the implementation of language standards such as C99 or changes to the warnings generated by Wall Some of the changes area result of bug fixing and some old behaviors have been intentionally changed in order to Support new standards or relaxed in standards conforming ways to facilitate 96 Annandiv R Channac in Vlarcinn 2 N Appen dix B Chan ges in version o U compilation or runtime performance Some of these changes are not visible to the naked eye and will not cause problems when updating from older versions However some of these changes are visible and can cause grief to users porting to Red Hat Developer Toolset s version of GCC The following text attempts to identify major issues and suggests solutions B 2 1 2 1 C Constant expressions are now handled by GCC in a way that conforms to C90 and C99 For code expr
144. n see the resources listed below See Also Section A 3 Changes in elfutils provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of elfutils and the version distributed in the previous release of Red Hat Developer Toolset Chapter 1 Red Hat Developer Toolset provides an overview of Red Hat Developer Toolset and more information on how to install iton your system Chapter 3 GNU Compiler Collection GCC provides information on how to compile programs written in C C and Fortran Chapter 4 binutils explains how to use the binutils a collection of binary tools to inspect and manipulate object files and binaries Chapter 6 dwz explains how to use dwz to optimize DWARF debugging information contained in ELF shared libraries and ELF executables for size 36 Chapter 6 dwz Chapter 6 dwz dwz is a command line tool that attempts to optimize DWARF debugging information contained in ELF shared libraries and ELF executables for size To do so dwz replaces DWARF information representation with equivalent smaller representation where possible and reduces the amount of Red Hat Developer Toolsetis distributed with dwz 0 11 6 1 Installing dwz In Red Hat Developer Toolset the dwz utility is provided by the devtoolset 3 dwz package and is 6 2 Using dwz To optimize DWARF debugging information in a binary file run the dwz tool as follows scl enable devtoolse
145. n 1 5 Installing Red Hat Developer Toolset 13 2 Using OProfile To run any ofthe tools that are distributed with OProfile type the following ata shell promptas root scl enable devtoolset 3 tool option See Table 13 1 Tools Distributed with OProfile for Red Hat Developer Toolset for a list of tools that Chapter 13 OProfile are distributed with O Profile For example to use the ophelp command to list available events in the XML format type scl enable devtoolset 3 ophelp X Note that you can execute any command using the scl utility causing it to be run with the Red Hat Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent This allows you to run a shell session with Red Hat Developer Toolset OProfile as default scl enable devtoolset 3 bash To verify the version of OProfile you are using at any point type the following ata shell prompt which opcontrol Red Hat Developer Toolset s opcontrol executable path will begin with opt Alternatively you can use the following command to confirm that the version number matches that for Red Hat Developer Toolset OProfile opcontrol version 13 3 Additional Resources A detailed description of OProfile and its features is beyond the scope of this book For more information see the resources listed below Installed Documentation oprofile 1 The manual page named oprofile provides an overview of O
146. n Eclipse The OProfile plug in which integrates OProfile with Eclipse The Perf plug in which integrates the perf tool with Eclipse The Eclipse Spec File Editor which allows you to maintain RPM spec files The SystemTap plug in which integrates SystemTap with Eclipse The Valgrind plug in which integrates Valgrind with Eclipse a This package is installed as a dependency of devtoolset 3 eclipse linuxtools 2 1 Installing Eclipse In Red Hat Developer Toolset the Eclipse development environment is provided as a collection of RPM packages and is automatically installed with the devtoolset 3 ide package as described in Section 1 5 Installing Red Hat Developer Toolset For a list of available components see The Red Hat Developer Toolset version of Eclipse fully supports C C and Java development but does not provide support for the Fortran programming language 17 User Guide 2 2 Using Eclipse To start the Red Hat Developer Toolset version of Eclipse either select Applications gt Programming DTS Eclipse from the panel or type the following at a shell prompt scl enable devtoolset 3 eclipse During its startup Eclipse prompts you to select a workspace that is a directory in which you want to store your projects You can either use workspace which is the default option or click the Browse button to browse your file system and select a custom directory Additionally you can select the U
147. n atomic manner int _xtest void Returns a non zero value if a transaction is currently active or zero if itis not void _xabort unsigned char status Aborts the current transaction When no transaction is active this is ano op The parameter status is included in the return value of any _xbegin call thatis aborted by this function The following example illustrates the use of these intrinsics if status _xbegin _XBEGIN_STARTED i some code _xend else examine the status to see why the transaction failed and possibly ee lay Transactions Using Transactional Synchronization Extensions Transactions in the transactional memory feature the fgnu tm option of GCC can now be run using Transactional Synchronization Extensions TSX if available on x86 hardware m U J User Guide Support for AMD Family 15h Processors The x86 backend of GCC now supports CPUs based on AMD Family 15h cores with the 64 bit x86 instruction set support This can be enabled by using the march bdver3 option Support for AMD Family 16h Processors The x86 backend of GCC now supports CPUs based on AMD Family 16h cores with the 64 bit x86 instruction set support This can be enabled by using the march btver2 option B 2 1 5 ABI Compatibility This section describes compatibility between the Red Hat Developer Toolset compilers and the system compilers at the application binary interface ABI level B 2 1 5 1 C AB
148. n be worked around with fno access control the second is only rejected with pedantic Experimental C Features g now supports a new command line option std c 1y New thread_local Keyword g now implements the C 11 thread_local keyword In comparison with the GNU __ thread keyword thread_local allows dynamic initialization and destruction semantics A m m L awa ne p J ae WS Annandiy PR Chanqaac in Varcinn 2 N Appen dix B Chan ges in version o U The use of the thread_local keyword has currently one important limitation when the dilclose function is used to unload a dynamically loaded DSO that contains the definition ofa thread_local object the thread_local object is destroyed its destructor is called and the DSO is unmapped from the address space of the process If a thread in the process tries to access the thread_local object after this the program may terminate unexpectedly As a result the programmer may have to take extra care to ensure that thread_local objects in a DSO are not referred after ithas been unloaded See also the next item for dynamic initialization issues Dynamic Initialization of Thread local Variables The C 11 and OpenMP standards allow thread local and thread private variables to have dynamic that is runtime initialization To support this any use of such a variable goes through a wrapper function that performs necessary initialization When the use and definition
149. nd is 9 2 Using Itrace To run the Ltrace utility on a program you want to analyze type the following ata shell prompt scl enable devtoolset 3 ltrace program argument Replace program with the name of the program you want to analyze and argument with any command line options and arguments you want to supply to this program Alternatively you can run the utility on an already running process by using the p command line option followed by the process ID scl enable devtoolset 3 ltrace p process_id Note that you can execute any command using the scl utility causing it to be run with the Red Hat Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent This allows you to run a shell session with Red Hat Developer Toolset 1 trace as default scl enable devtoolset 3 bash To verify the version of Ltrace you are using at any point type the following ata shell prompt which ltrace Red Hat Developer Toolset s Ltrace executable path will begin with opt Alternatively you can use the following command to confirm that the version number matches that for Red Hat Developer Toolset 1 trace ltrace V 9 2 1 Redirecting Output to a File 53 User Guide By default Ll trace prints the name of each system call its arguments and the return value to standard error output To redirect this output to a file use the o command line option followed by the file name scl enable devtoo
150. nd memcheck tool the client code can now selectively disable and re enable reporting of invalid address errors in specific ranges using new client requests The Valgrind memcheck tool now supports more accurate checking of system call parameters that use uninitialized fields in structures In the Valgrind memcheck tool it is now possible to disable the mismatched checking of memory deallocation using the free or delete functions by specifying the new show mismatched frees no yes flag with the default value being yes In the Valgrind helgrind tool more information about race conditions and locks is now shown in error messages as the new Valgrind gdbserver monitor command returns the list of locks their location and their status A 7 Changes in Dyninst Red Hat Developer Toolset 3 1 is distributed with Dyninst 8 2 1 which provides a number of bug fixes and feature enhancements over the version included in Red Hat Enterprise Linux and the previous version of Red Hat Developer Toolset Below is a comprehensive list of new features in this release A 7 1 Changes Since Red Hat Developer Toolset 3 0 and Red Hat Enterprise Linux 7 1 A number of bugs have been fixed In addition to that the following features have been added since the release of Dyninst in Red Hat Developer Toolset 3 0 and Red Hat Enterprise Linux 7 1 Dyninst now fails gracefully when invalid line information is discovered The parsing of DWARF location lists has be
151. ndividual loop iterations do not have any interdependencies Full single image support except for polymorphic coarrays has been added and can be enabled by using the fcoarray single command line option Additionally GNU Fortran now provides preliminary support for multiple images via an MPI based coarray communication library Note that the library version is not yet usable as remote coarray access is not yet possible The STOP and ERROR STOP statements have been updated to support all constant expressions The CONTIGUOUS attribute is now supported Use of ALLOCATE with the MOLD argument is now supported The STORAGE_ SIZE intrinsic inquiry function is now supported The NORM2 and PARITY intrinsic functions are now supported The following bit intrinsics have been added the POPCNT and POPPAR bit intrinsics for counting the number of 1 bits and returning the parity the BGE BGT BLE and BLT bit intrinsics for bitwise comparisons the DSHIFTL and DSHIFTR bit intrinsics for combined left and right shifts the MASKL and MASKR bit intrinsics for simple left and right justified masks the MERGE_ BITS bit intrinsic for a bitwise merge using a mask the SHIFTA SHIFTL and SHIFTR bit intrinsics for shift operations the transformational bit intrinsics IALL IANY and IPARITY The EXECUTE_COMMAND_LINE intrinsic subroutine is now supported The IMPURE attribute for procedures is now supported This allows the use of ELEMENTAL procedures without
152. ng beta releases If you have previously installed any pre release version of Red Hat Developer Toolset uninstall it from your system as described in Section L l Uninstalling Red Hat Developer Toolset and install the new version 1 6 2 Updating to a Major Version When a new major version of Red Hat Developer Toolset is available you can install itin parallel with the previous version For detailed instructions on how to install Red Hat Developer Toolset on your system see Section 1 5 Installing Red Hat Developer Toolset 1 7 Uninstalling Red Hat Developer Toolset To uninstall Red Hat Developer Toolset packages from your system type the following ata shell prompt as root yum remove devtoolset 3 libasan libatomic libcilkrts libitm liblsan libtsan libubsan This removes the GNU Compiler Collection GNU Debugger binutils and other packages that are a part of Red Hat Developer Toolset from the system Red Hat Developer Toolset 3 1 for Red Hat Enterprise Linux 7 no longer includes the libatomic and 1ibitm libraries which the above command attempts to remove because they are not required for a proper function of Red Hat Developer Toolset components on that system Nevertheless the above command works as expected even on Red Hat Enterprise Linux 7 Note that the uninstallation of the tools provided by Red Hat Developer Toolset does not affect the Red Hat Enterprise Linux system versions of these tools 1 8 Using Red H
153. ng debugging has been enhanced The remote launch function has been enhanced to allow in place editing of connections The Mylyn task management subsystem has been updated from version 3 12 to version 3 14 This new release includes the following change Wikitext now supports the Markdown language and can output the XHTML format The Eclipse Linux Tools plug in collection has been updated from version 3 1 to 3 2 This new minor release includes The GCov and GProf plugins have been improved to automate the setting of compiler options and provide a better vizualization of data The LibHover plugin has been improved to parse Devhelp data significantly faster EGit a Git integration plug in for Eclipse and JGit a Java library implementing Git have been updated from version 3 4 1 to 3 6 1 This update includes Additional options have been added to many JGit commands o P 1 a 5 O Support for Git submodules has been added to JGit The interactive rebase view has been improved Stash actions are now exposed in the user interface A 2 Changes in GCC Red Hat Developer Toolset 3 1 is distributed with GCC 4 9 2 which provides a number of bug fixes and a new feature over the version included in the previous version of Red Hat Developer Toolset A 2 1 Changes Since Red Hat Developer Toolset 3 0 The following features have been added since the release of GCC in Red Hat Developer Toolset 3 0 Anew option fsanitize kernel
154. ntrols whether GDB instructs the target to step through the corresponding range of addresses If disabled single steps are always issued The show range stepping command shows the value of this setting This is set to on by default set startup with shell off on Controls whether the shell is used to start subprocesses If set to of f processes are started directly The show startup with shell command shows the value of this setting This is set to on by default set code cache off on Controls whether the target memory cache is used for accesses to code segments disregarding any configured memory regions This improves performance of remote debugging particularly disassembly The show code cache command shows the value of this setting This is set to on by default set print symbol loading off brief full Controls whether to print informational messages when loading symbol information for a file The default value for this option is Full but when debugging programs with large numbers of shared libraries the amount of output becomes less useful The show print symbol loading command shows the value of this setting maint ada set ignore descriptive types on off Controls whether the debugger ignores descriptive types in Ada programs The default value is of f thatis not to ignore the descriptive types See the user manual for more details on descriptive types and the intended usage of this option Themaint ada show ignore desc
155. numbers ar Creates modifies and extracts files from archives as The GNU assembler c filt Decodes mangled C symbols dwp Combines DWARF object files into a single DWARF package file elfedit Examines and edits ELF files gprof Display profiling information ld The GNU linker ld bfd An alternative to the GNU linker ld gold Another alternative to the GNU linker nm Lists symbols from object files objcopy Copies and translates object files objdump Displays information from object files ranlib Generates an index to the contents of an archive to make access to this archive faster readelf Displays information about ELF files size Lists section sizes of object or archive files strings Displays printable character sequences in files strip Discards all symbols from object files 4 1 Installing binutils In Red Hat Developer Toolset binutils are provided by the devtoolset 3 binutils package and are automatically installed with devtoolset 3 toolchain as described in Section 1 5 Installing Red Hat Developer Toolset 4 2 Using the GNU Assembler To produce an object file from an assembly language program run the as tool as follows scl enable devtoolset 3 as option 0 object_file source_file This creates an object file named object_file in the current working directory User Guide Note that you can execute any command using the scl utility causing it to be run with the Red Hat Developer Toolset bina
156. o control whether typedef definitions are displayed by the ptype command This functionality is enabled by default New set filename display basename relative absolute and show filename display commands have been added These commands allow you to control the way in which file names are displayed the basename option displays only the base name of a file name relative displays a path relative to the compilation directory and absolute displays an absolute path to the file The default option is relative to preserve the previous behavior New set trace buffer size and show trace buffer size commands have been added These commands allow you to control the size of the trace buffer for a target New set remote trace buffer size packet auto on off and show remote trace buffer size packet commands have been added These commands allow you to control the use of the remote protocol QTBuffer size packet New set debug notification and show debug notification commands have been added These commands allow you to control whether to display debugging information for asynchronous remote notification This functionality is disabled by default Anewcommand info macros has been added This command accepts linespec as an optional argument and can be used to display the definitions of macros at that linespec location Note that in order to do this the debugged program must be compiled with the g3 command line option to have macro information available in it
157. o run this program on the command line change to the directory with the executable file and type file_name Example 3 4 Running a C Program on the Command Line hello Hello World 3 2 4 C Compatibility Objects compiled with Red Hat Developer Toolset 2 and Red Hat Developer Toolset 3 in C 98 mode the default mode are compatible with each other and with objects compiled with the Red Hat Enterprise Linux system compilers in C 98 mode Objects compiled in C 11 mode that is with std c 11 are compatible with all of the above C 98 objects but are not guaranteed to be compatible with C 11 objects compiled with a different major version of the compiler That is if some C 11 objects previously compiled with Red Hat Developer Toolset 2 are rebuilt with Red Hat Developer Toolset 3 all C 11 objects should be rebuilt For the same reasons C 11 objects built with this release of Red Hat Developer Toolset may need to be rebuilt to be compatible with objects built by future releases of Red Hat Developer Toolset or Red Hat Enterprise Linux N An object compiled with DTS 2 x in DTS 3 xin RHEL system DTS 2 x in DTS 3 x In C 98 mode C 98 mode compilers in C 11 mode C 11 mode C 98 mode DTS 2 x i ai F v V V Y DTS 3 x In C 98 mode An object compiled RHELsystem with compilers in C 98 mode DTS 2 x In C 11 mode DTS 3 x In C 11 mode E A a Ss ia X V X Unsupported V Supported
158. of CPU time and why 717 User Guide Part VI Getting Help 78 Chapter 15 Accessing Red Hat Product Documentation Chapter 15 Accessing Red Hat Product Documentation Red Hat Product Documentation located at hitps access redhat com site documentation serves as a central source of information It is currently translated in 23 languages and for each product it provides different kinds of books from release and technical notes to installation user and reference guides in HTML PDF and EPUB formats Below is a brief list of documents that are directly or indirectly relevant to this book Red Hat Developer Toolset Red Hat Developer Toolset 3 1 Release Notes The Release Notes for Red Hat Developer Toolset 3 1 provide more information about this product Red Hat Software Collections Packaging Guide The Software Collections Packaging Guide explains the concept of Software Collections and documents how to create build and extend them Red Hat Enterprise Linux Red Hat Enterprise Linux 6 Developer Guide and Red Hat Enterprise Linux 7 Developer Guide The Developer Guides for Red Hat Enterprise Linux 6 and 7 provide more information about libraries and runtime support compiling and building debugging and profiling Red Hat Enterprise Linux 6 Installation Guide The Installation Guide for Red Hat Enterprise Linux 6 explains how to obtain install and update the system Red Hat Enterprise Linux 6 Inst
159. of the variable are in the same translation unit this overnead can be optimized away but when the use is in a different translation unit there is significant overhead even if the variable does not actually need dynamic initialization If the programmer can be sure that no use of the variable in a non defining translation unit needs to trigger dynamic initialization either because the variable is statically initialized or a use of the variable in the defining translation unit will be executed before any uses in another translation unit they can avoid this overhead by using the new fno extern tls init option By default g uses the fextern tls init option C 11 Attribute Syntax g now implements the C 11 attribute syntax for example noreturn void f C 11 Alignment Specifier g now implements the C 11 alignment specifier for example alignas double int 1 B 2 1 2 3 C C Warnings GCC 4 7 0 and later adds a number of new warnings that are either enabled by default or by using the Wall option Although these warnings do not result in a compilation failure on their own often Wall is used in conjunction with Werror causing these warnings to act like errors This section provides a list of these new or newly enabled warnings Unless noted otherwise these warnings apply to both C and C The behavior of the wall command line option has changed and now includes the new warning flags Wunused but set variable
160. ommand using the scl utility causing it to be run with the Red Hat Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent This allows you to run a shell session with Red Hat Developer Toolset strace as default scl enable devtoolset 3 bash To verify the version of strace you are using at any point type the following ata shell prompt which strace Red Hat Developer Toolset s strace executable path will begin with opt Alternatively you can use the following command to confirm that the version number matches that for Red Hat Developer Toolset strace strace V 8 2 1 Redirecting Output to a File By default strace prints the name of each system call its arguments and the return value to 48 Chapters strace standard error output To redirect this output to a file use the o command line option followed by the file name scl enable devtoolset 3 strace o file_name program argument Replace file_name with the name of the file Example 8 1 Redirecting Output to a File Consider a slightly modified version ore fi bonacci file from Example k i P Compiling aC optionally allows you to specify how many members of this sequence to list To run the strace utility on this file and redirect the trace output to fibonacci log type scl enable devtoolset 3 strace o fibonacci log fibonacci 20 1123 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181 6765 This creat
161. on GCC writes the information to the standard error output stream For example to display a list of optimizations that were enabled by the 02 option but had no effect when compiling a file named foo c type gcc 02 fopt info missed foo c Appendix B Changes in Version 3 0 New floop nest optimize Option Anew command line option floop nest optimize has been added This option enables an experimental ISL based loop nest optimizer a generic loop nest optimizer that is based on the Pluto optimization algorithms and that calculates a loop structure optimized for data locality and Hot and Cold Attributes on Labels The hot and cold function attributes can now also be applied to labels Hot labels tell the compiler that the execution path following the label is more likely than any other execution path and cold labels convey the opposite meaning These attributes can be used in cases where __builtin_expect cannot be used for instance with a computed goto or asm goto B 2 1 9 Debugging Enhancements DWARF4 DWARF4 is now used as the default debugging data format when generating debugging information To get the maximum benefit from this new debugging representation use the latest version of Valgrind elfutils and GDB included in this release New gsplit dwarf Option Anew command line option gsplit dwarf has been added This option tells the compiler driver to separate as much DWARF debugging information as possible into a s
162. ons can be nested within other atomic and relaxed transactions but relaxed transactions can only be nested within other relaxed transactions Furthermore relaxed transactions are likely to be executed with less performance but this depends on the implementation and available hardware GCC verifies these restrictions statically at compile time for example the requirements on code allowed to be called from within atomic transactions This has implications for when transactions call functions that are defined within other compilation unit Source file or within libraries To enable such cross compilation unit calls for transactional code the respective functions must be marked to contain code that is safe to use from within atomic transactions Programmers can do so by adding the transaction_safe function attribute to the declarations of these functions and by including this declaration when defining the function In turn GCC then verifies that the code in these functions is safe for atomic transactions and generates code accordingly If the programmer does not follow these constraints and or steps compile time or link time errors occur Note that within a compilation unit GCC detects automatically whether a function is safe for use within transactions and the attributes therefore typically do not need to be added See the draft specification linked above for further details GCC s transactional memory support is designed in such a way that it doe
163. optimization can be turned off by using the new command line option fno aggressive loop optimizations B 2 2 Changes Since Red Hat Developer Toolset 2 1 and Red Hat Enterprise Linux 7 0 The following features have been added since the release of GCC in Red Hat Developer Toolset 2 1 and Red Hat Enterprise Linux 7 0 B 2 2 1 General Changes Improved Link Time Optimization Link time optimization LTO has been improved in a number of ways Better type merging allows for a faster operation and less memory is required Virtual functions are now being removed early in the LTO process which results in smaller object files and significant improvements to link time Improved Inter Procedural Analysis Inter procedural analysis IPA has been improved especially the devirtualization optimization Also speculative devirtualization optimization has been added which can be enabled using the fdevirtualize speculatively option Improved Profiling Support for profiling code has been made more reliable Support for the Intel AVX 512 Architecture GCC now supports the Intel AVX 512 target architecture as well as a number of new Intel microarchitectures New Wdate time Warning Option Anew warning option Wdate time has been added It triggers a warning when the _ DATE ___ __TIME__ or ___TIMESTAMP__ macros are used New GCC ivdep Pragma LY ons Appendix B Changes in Version 3 0 Anew pragma pragma GCC ivd
164. ority More information on escalation including contacts is available at https access redhat com support policy mgt_escalation html 16 3 Re opening a Service Request If there is more relevant information regarding a closed service request such as the problem reoccurring you can re open the request via the Red Hat Customer Portal at https access redhat com support policy mgt_escalation html or by calling your local support center the details of which can be found at https access redhat com support contact technicalSupport html Important In order to re open a service request you need the original service request number 16 4 Additional Resources For more information see the resources listed below Online Documentation Getting Started The Getting Started page serves as a Starting point for people who purchased a Red Hat su bscription and offers the Red Hat Welcome kit and the Quick Guide to Red Hat Support for download How can a RHEL Self Support subscription be used A Knowledgebase article for customers with a Self Support subscription Red Hat Global Support Services and public mailing lists A Knowledgebase article that answers frequent questions about public Red Hat mailing lists 82 V Arran A lv A Crananc in i Arce F rn ke Appen dix A Chan ges IN Version 5 Appendix A Changes in Version 3 1 The sections below document features and compatibility changes introduced in R
165. orrect locking order or misuse of the POSIX pthreads API When a problem is detected the plug in displays error markers on the corresponding lines in the source code The Eclipse Linux Tools plug in collection has been updated This update includes support for the operf command line tool in the OProfile plug in the operf command is now used by default to make generic setup easier an enhanced RPM Stubby plug in which is now able to generate RPM spec files from Perl makefiles Ruby gamespec files and Python setup py files an enhanced Spec File Editor plug in which is now able to download source files prepare a buildroot and also provides a Build menu a corresponding toolbar and improved support for hyperlinks in the editor an enhanced SystemTap stp files editor which now has improved formatting capabilities improved SystemTap graphing which has been streamlined to be easier to launch and configure B 1 2 Changes Since Red Hat Developer Toolset 2 1 The Eclipse Platform has been updated from version 4 3 1 to 4 4 0 As this is a feature release it contains a number of new features bug fixes and optimizations including the following SWT Standard Widget Toolkit gained aGTK 3 backend which provides for a cohesive look and feel with the default desktop user environment on Red Hat Enterprise Linux 7 thus streamlining the user experience There is also a preliminary support for WebKit 2 x for an enhanced stability of the
166. ow auto load have been added and can be used to control automatic loading of files The set auto load gdb scripts and show auto load gdb scripts commands control automatic loading of GDB scripts Theset auto load python scripts and show auto load python scripts commands control automatic loading of Python scripts The set auto load local gdbinitand show auto load local gdbinit commands control automatic loading of gdbinit from the current working directory The set auto load libthread db and show auto load libthread db commands control automatic loading of inferior specific Libthread_db The set auto load scripts directory and show auto load scripts directory commands control the list of directories from which to automatically load GDB and Python scripts The set auto load safe pathand show auto load safe path commands control the list of directories from which it is safe to automatically load all previously mentioned items The set debug auto load and show debug auto load commands control displaying of debugging information for all previously mentioned items The set auto load off command can be used to disable automatic loading globally You can also use show auto load with no subcommand to display current settings of all previously mentioned items Themaint set python auto load on off command has been replaced with set auto load python scripts on off The maintenance print section scripts command has been renamed to info auto
167. ows the value of this setting maint set per command time on off Enable or disable the displaying of the execution time of each command The maint show per command time command shows the value of this setting maint set per command symtab on off Enable or disable the displaying of basic symbol table statistics for each command The maint show per command symtab command shows the value of this setting New Command Line Options Two new command line options have been added Anew command line option configuration has been added It displays the details of the configuration options with which GDB was built This option is the equivalent of the show configuration interactive command Anew command line option D has been added This option is an alias for the data directory option This option allows you to specify where GDB looks for its auxiliary files Changes in the Machine Interface Interpreter GDB Ml The machine interface interpreter GDB MI has been improved in a number of ways All MI commands now accept an optional Language option Support for this feature can be verified by using the List features command which should contain the Language option item Anew command info gdb mi command has been added It allows the user to determine whether a GDB MI command is supported or not Annandiv R Clraannac in V larcinn 2 N Appen dix B Chan ges in version o U The error result record returned when tr
168. pported The achieved reduction in the number of control packets sent to and from GDB results in an improved performance GDB now understands the new tvar element which has been added to the XML in the traceframe information Ithas the 1d of the collected trace state variables The typeid C operator is now supported Anew convenience variable exception has been added It holds the exception that is being thrown or caught at an exception related catchpoint Exception related catchpoints such as catch throw can now filter exceptions by type using a supplied regular expression Anew convenience variable _exitsignal has been added It can be used to determine the signal number with which a program terminates if it dies due to an uncaught signal The exitcode is then automatically set to void Commands such as c amp S amp can now be executed in the background if the target supports them In previous versions asynchronous execution had to be explicitly enabled using the now deprecated set target async oncommand The btrace record target now supports the record goto command For locations inside the execution trace the back trace is computed based on the information stored in the execution trace The btrace record target now supports limited reverse execution and replay The target does not record data and therefore does not allow for reading the memory or registers Annandiy PR Chanqaac in Varcinn 2 N Appen dix B Chan g
169. q with a simple e is not equivalent GFORTRAN_TMPDIR Environment Variable The GFORTRAN_TMPDIR environment variable for specifying a non default directory for files opened with STATUS SCRATCH is not used anymore Instead gfortran checks the POSIX GNU standard TMPDIR environment variable and if TMPDIR is not defined gfortran falls back to other methods to determine the directory for temporary files as documented in the user manual TS 29113 Assumed types TYPE are now supported Experimental support for assumed rank arrays dimension has been added Note that at the moment the gfortran array descriptor is used which is different from the array descriptor defined in TS 29113 For more information see the header file of gfortran or use the Chasm language interoperability tools B 2 1 3 9 Caveats The version of module files the mod files has been incremented Fortran modules compiled by earlier GCC versions have to be recompiled when they are used by files compiled with GCC 4 8 as this version of GCC is not able to read mod files created by earlier versions attempting to do so fails with an error message The ABI of the produced assembler data itself has not changed object files and libraries are B 2 1 3 10 ABI Compatibility Some internal names used in the assembler or object file have changed for symbols declared in the specification part of a module If an affected module or a file using it via use associ
170. r Red Hat Developer Toolset for a list of tools that are distributed with SystemTap For example to run the stap tool to build an instrumentation module type scl enable devtoolset 3 stap option argument Note that you can execute any command using the scl utility causing it to be run with the Red Hat Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent This allows you to run a shell session with Red Hat Developer Toolset SystemTap as default scl enable devtoolset 3 bash To verify the version of SystemTap you are using at any point type the following ata shell prompt which stap Red Hat Developer Toolset s stap executable path will begin with opt Alternatively you can use the following command to confirm that the version number matches that for Red Hat Developer Toolset SystemTap stap V 11 3 Additional Resources A detailed description of SystemTap and its features is beyond the scope of this book For more information see the resources listed below Installed Documentation stap 1 The manual page for the stap command provides detailed information on its usage as well as references to other related manual pages To display the manual page for the version included in Red Hat Developer Toolset type scl enable devtoolset 3 man stap 63 User Guide staprun 8 The manual page for the staprun command provides detailed information on its usag
171. r the starting number scanf d amp i for 1 0 i print_iteration i return o This program prompts the user to enter a starting number and then counts down to 1 calling the print_iteration function for each iteration in order to print the number to the standard output To compile this program on the command line using the g compiler from Red Hat Developer Toolset type the following ata shell prompt scl enable devtoolset 3 g g o exercise exercise C Now consider another source file named count stp with the following contents usr bin stap global count 0 probe process function print_iteration count probe end printf Function executed d times n count This SystemTap script prints the total number of times the print_iteration function was called during the execution of a process To run this script on the exercise binary file type 72 scl enable devtoolset 3 stap dyninst c exercise count stp Enter the starting number 5 Iteration number 5 Iteration number 4 Chapter 14 Dyninst Iteration number 3 Iteration number 2 Iteration number 1 Function executed 5 times 14 2 2 Using Dyninst as a Stand alone Application Before using the Dyninst library as a stand alone application set the value of the DYNINSTAPI_RT_LIB environment variable to the path to the runtime library file You can do so by typing the following ata shell prompt export DYNINS
172. ram from a variable of any complexity to a valid expression or even a library function However the most common task is to display the value of a variable To display the current value of a certain variable run the following command print variable_name Example 7 9 Displaying the Current Values of Variables Assuming that you have followed the instructions in Example 7 8 Executing the fibonacci Binary you can display the current values of variables a and b as follows gdb print a 1 0 gdb print b 520 AG 7 8 Continuing Execution To resume the execution of the program you are debugging after it reached a breakpoint run the following command continue The execution stops again when another breakpoint is reached To skip a certain number of breakpoints typically when you are debugging a loop you can run the continue command in the following form continue number The gdb utility also allows you to stop the execution after executing a single line of code To do so run step Finally you can execute a certain number of lines by using the step command in the following form step number Example 7 10 Continuing the Execution of the fibonacci Binary File you can resume the execution by running the following command gdb continue Continuing Breakpoint 1 main argc 1 argv 0x 7fffffffe4d8 at fibonacci c 10 10 printf ld b The execution stops the next time the breakpoint is reached To
173. ran Chapter 8 strace documents how to use the strace utility to monitor system calls that a program uses and signals it receives Chapter 10 memstomp documents how to use the memstomp utility to identify calls to library functions with overlapping memory regions that are not allowed by various standards 47 User Guide Chapter 8 strace strace is a diagnostic and debugging tool for the command line that can be used to trace system calls that are made and received by a running process It records the name of each system call its arguments and its return value as well as signals received by the process and other interactions with the kernel and prints this record to standard error output or a selected file Red Hat Developer Toolset is distributed with strace 4 8 8 1 Installing strace In Red Hat Enterprise Linux the strace utility is provided by the devtoolset 3 strace package and is 8 2 Using strace To run the strace utility on a program you want to analyze type the following ata shell prompt scl enable devtoolset 3 strace program argument Replace program with the name of the program you want to analyze and argument with any command line options and arguments you want to supply to this program Alternatively you can run the utility on an already running process by using the p command line option followed by the process ID scl enable devtoolset 3 strace p process_id Note that you can execute any c
174. re installing Red Hat Developer Toolset install all available Red Hat Enterprise Linux updates 1 5 1 Installing All Available Components To install all components that are included in Red Hat Developer Toolset install the devtoolset 3 package by typing the following ata shell prompt as root yum install devtoolset 3 This installs the Eclipse development environment all development debugging and performance monitoring tools and other dependent packages to the system Alternatively you can choose to install only a selected package group as described in Section 1 5 2 Installing Individual Package Groups Note that since Red Hat Developer Toolset 3 0 the sc utils package is not a part of Red Hat Developer Toolset which is a change from preceding versions where the scl utility was installed along with the Red Hat Developer Toolset software collection 1 5 2 Installing Individual Package Groups To make it easier to install only certain components such as the integrated development environment or the software development toolchain Red Hat Developer Toolset is distributed with a number of meta packages that allow you to install selected package groups as described in Table 1 2 Red Hat Developer Toolset Meta Packages Table 1 2 Red Hat Developer Toolset Meta Packages Package Name Description Installed Components devtoolset 3 ide Integrated Development Eclipse Environment devtoolset 3 perftools Performance monitorin
175. reakpoints in the task context is now supported The Eclipse Linux Tools plug in collection has been updated from version 2 2 to 3 1 This new major release includes The GCov plugin has been considerably improved by making it use and annotate standard CDT editors instead of GCov specific ones Appendix B Changes in Version 3 0 The GCov and GProf plugins now support an automatic changing of compiler and linker options for projects which simplifies the initial setup The Systemtap plugin went through a major overhaul of its user interface making it easier faster and more reliable for generating editing and displaying graphics filtering gathered datasets and manipulating the probe and function inventories The speed of indexing the Devhelp GTK and GNOME documentation has been improved significantly EGit a Git integration plug in for Eclipse and JGit a Java library implementing Git have been updated from version 3 1 to 3 4 1 This update includes The command line interface has been greatly enhanced Commands now support more parameters and new commands have been added Speed has been improved by making use of the Java 7 API Support has been added for performing interactive rebasing in the user interface Blame annotations now expose more information and provide a cross reference capability B 2 Changes in GCC Red Hat Developer Toolset 3 0 is distributed with GCC 4 9 1 which provides a number of bug fixes and new f
176. regular repositories and optional repositories replace variant with the Red Hat Enterprise Linux system variant server or workstation and version with the Red Hat Enterprise Linux system version 6 eus 6 or 7 4 Enable the repositories from step no 3 by running the following command as root subscription manager repos enable repository Replace repository with the name of the repository to enable User Guide Once the subscription is attached to the system you can install Red Hat Developer Toolset as described in Section 1 5 Installing Red Hat Developer Toolset For more information on how to register your system using Red Hat Subscription Management and associate it with subscriptions see the Red Hat Subscription Management collection of guides 1 4 2 Using RHN Classic If you are running Red Hat Enterprise Linux 6 and your system is registered with RHN Classic complete the following steps to subscribe to Red Hat Software Collections which includes Red Hat Developer Toolset 1 Determine the exact name of the Red Hat Software Collections channel To do so type the following ata shell prompt as root to display a list of all channels that are available to you rhn channel available channels The name of the channel depends on the specific version of Red Hat Enterprise Linux you are using and is in the following format rhel x86_ 64 variant version rhscl 1 In addition certain packages such as devtoolset 3 gcc
177. rehensive list of new features in this release A 6 1 Changes Since Red Hat Developer Toolset 3 0 The following features have been added since the release of Valgrind included in Red Hat Developer Toolset 3 0 The db attach option is now deprecated and will be removed in the next feature release The built in Valgrind gdbserver capabilities see the vgdb options are superior and should be used instead 86 Error messages that include stack traces can now show inline function calls if the DWARF debugging information format is available These can also be used in suppressions Error messages concerning dubious arguments for example to malloc or calloc now include a stack trace and can be used in suppressions The C demangler has been updated for better C 11 support The Valgrind gdbserver functionality now supports the display of thread local variables and storage __thread Three new monitor commands have been added to Valgrind v info location address to show more information about an address v info stats to show various Valgrind core and tool statistics v set hostvisibility which allows Valgrind gdbserver to provide access to Valgrind internal host status and memory Anew command line option vgdb stop at eventi event2 which allows the user to ask the Valgrind gdbserver to stop at the start of program execution at the end of the program execution and when Valgrind aborts on internal errors In the Valgri
178. ries used in preference to the Red Hat Enterprise Linux system equivalent This allows you to run a shell session with Red Hat Developer Toolset as as default scl enable devtoolset 3 bash To verify the version of as you are using at any point type the following at a shell prompt which as Red Hat Developer Toolset s as executable path will begin with opt Alternatively you can use the following command to confirm that the version number matches that for Red Hat Developer Toolset as as V 4 3 Using the GNU Linker To create an executable binary file or a library from object files run the 1d tool as follows scl enable devtoolset 3 ld option o output_file object_file This creates a binary file named output_file in the current working directory If the o option is omitted the compiler creates a file named a out by default Note that you can execute any command using the scl utility causing it to be run with the Red Hat Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent This allows you to run a shell session with Red Hat Developer Toolset ld as default scl enable devtoolset 3 bash To verify the version of 1d you are using at any point type the following ata shell prompt which 1d Red Hat Developer Toolset s 1d executable path will begin with opt Alternatively you can use the following command to confirm that the version number matches that for Red Hat
179. riptive types command shows the value of this setting set auto connect native target on off Controls whether GDB may automatically connect to the native target when not connected to any target yet If set to on GDB attempts the run attach and other commands with the native target The show auto connect native target command shows the value of this setting set record btrace replay memory access read only read write Controls what memory accesses are allowed during replays The show record btrace replay memory access command shows the value of this setting maint set target async on off Controls whether GDB targets operate in synchronous or asynchronous mode By default and if available asynchronous mode is used Set to off to simplify the debugging of problems that only occur in synchronous mode The maint show target async command shows the value of this setting set mi async on off Controls whether GDB MI uses asynchronous mode By default synchronous mode is used Set to on to enable background execution of commands The show mi async command shows the value of this setting This command supersedes the set target async command from previous versions of GDB The following series of new commands enables displaying GDB resources used by each executed command maint set per command space on off Enable or disable the displaying of the amount of memory used by each command The maint show per command space command sh
180. rmation see the resources listed below Installed Documentation as 1 ld 1 addr2line 1 ar 1 c filt 1 dwp 1 elfedit 1 gprof 1 nm 1 objcopy 1 objdump 1 ranlib 1 readelf 1 size 1 strings 1 strip 1 Manual pages for various binutils tools provide more information about their respective usage To display a manual page for the version included in Red Hat Developer Toolset type scl enable devtoolset 3 man tool 33 User Guide Online Documentation Documentation for binutils The binutils documentation provides an in depth description of the binary tools and their usage See Also 34 Section B 3 Changes in binutils provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux 6 6 and 7 0 versions of binutils and the version distributed in the 2 1 release of Red Hat Developer Toolset Chapter 1 Red Hat Developer Toolset provides an overview of Red Hat Developer Toolset and more information on how to install it on your system Chapter 5 elfutils explains how to use elfutils a collection of binary tools to inspect and manipulate ELF files Chapter 3 GNU Compiler Collection GCC provides information on how to compile programs written in C C and Fortran Chapter 5 elfutils Chapter 5 elfutils elfutils is a collection of various binary tools such as eu objdump eu readelf and other utilities that allow you to Speer ony manipulate ELF
181. rocess and its children in user space OProfile is well suited to collect system wide data on both user space and kernel space processes and requires root privileges to run Red Hat Developer Toolset is distributed with OProfile 0 9 9 This version is more recent than the version included in Red Hat Enterprise Linux and provides numerous bug fixes and enhancements Table 13 1 Tools Distributed with OProfile for Red Hat Developer Toolset Name Description oprofiled The OProfile daemon that collects profiling data opcontrol Starts stops and configures the OProfile daemon opannotate Generates an annotated source file or assembly listing from the profiling data oparchive Generates a directory containing executable debug and sample files opgprof Generates a summary ofa profiling session in a format compatible with gprof ophelp Displays a list of available events Opimport Converts a sample database file from a foreign binary format to the native format Oopjitconv Converts a just in time JIT dump file to the Executable and Linkable Format ELF opreport Generates image and symbol summaries of a profiling session ocount A new tool for counting the number of times particular events occur during the duration of a monitored command 13 1 Installing OProfile In Red Hat Developer Toolset OProfile is provided by the devtoolset 3 oprofile package and is automatically installed with devtoolset 3 perftools as described in Sectio
182. roved and speculative devirtualization optimization has been added Support for profiling code has been made more reliable Chapter 1 Red Hat Developer Toolset The Intel AVX 512 target architecture is now supported as well as a number of new Intel microarchitectures Support for C11 has been improved and ISO C11 atomics generic selections and thread local storage are now supported A subset of the functionality of C 11 auto is now provided in GNU C through a new extension __auto_type The C and C compilers now support the OpenMP 4 0 specification The g compiler offers improved support for various features of the C standard including generic lambdas variable length arrays and digit separators The C runtime library C 11 support has been improved and now includes experimental support for the upcoming ISO C standard C 14 GCC now adds support for Cilk an extension to the C and C languages for parallel programming The version of the GNU Debugger GDB included in Red Hat Developer Toolset provides the following new features Python scripting support has been enhanced in a number of ways Several new commands and enhancements in GDB MI have been added Support for the CTF Common Trace Format has been added The btrace record target has been enhanced in a number of ways The remote protocol and GDBserver the GDB remote stub have been enhanced in a number of ways Additionally the Red Hat Developer
183. rted Itis now possible to use complex arguments with the TAN SINH COSH TANH ASIN ACOS and ATAN functions Additionally the new functions ASINH ACOSH and ATANH have been added for real and complex arguments and ATAN Y X now serves as an alias for ATAN2 Y X The BLOCK construct has been implemented B 2 1 3 6 Fortran 2008 Compatibility The implementation of the ASYNCHRONOUS attribute in GCC is now compatible with the candidate draft of TS 29113 Technical Specification on Further Interoperability with C B 2 1 3 7 Fortran 77 Compatibility When the GNU Fortran compiler is issued with the fno sign zero option the SIGN intrinsic now behaves as if zero were always positive B 2 1 3 8 Other Changes BACKTRACE Intrinsic A new intrinsic subroutine BACKTRACE has been added This subroutine shows a backtrace at an arbitrary place in user code program execution continues normally afterwards Floating Point Numbers with q as Exponential Reading floating point numbers that use q for the exponential such as 4 0q0O is now supported as a vendor extension for better compatibility with old data files It is strongly recommended to use the equivalent but standard conforming e such as 4 0e0 for I O Appendix B Changes in Version 3 0 For Fortran source code consider replacing the q in floating point literals by a kind parameter such as 4 0e0_qp with a suitable qp Note that in Fortran source code replacing
184. s Chapter 13 OProfile explains how to use OProfile to determine which sections of code consume the greatest amount of CPU time and why Chapter 14 Dyninst documents how to use the Dyninst library to instrument a user space executable 64 Chapter 12 Valgrind Chapter 12 Valgrind Valgrind is an instrumentation framework that ships with a number of tools for profiling applications It can be used to detect various memory errors and memory management problems such as the use of uninitialized memory or an improper allocation and freeing of memory or to identify the use of improper arguments in system calls For a complete list of profiling tools that are distributed with the Red Hat Developer Toolset version of Valgrind see Table 12 1 Tools Distributed with Valgrind for Red Hat Developer Toolset Valgrind profiles an application by rewriting it and instrumenting the rewritten binary This allows you to profile your application without the need to recompile it but italso makes Valgrind significantly slower than other profilers especially when performing extremely detailed runs Itis therefore not suited to debugging time specific issues or kernel space debugging Red Hat Developer Toolset is distributed with Valgrind 3 10 1 This version is more recent than the version included in Red Hat Enterprise Linux and provides numerous bug fixes and enhancements Table 12 1 Tools Distributed with Valgrind for Red Hat Developer Tool
185. s an introduction to SystemTap and its usage Red Hat Enterprise Linux 7 SystemTap Beginners Guide The SystemTap Beginners Guide for Red Hat Enterprise Linux 7 provides an introduction to SystemTap and its usage Red Hat Enterprise Linux 6 SystemTap Tapset Reference The SystemTap Tapset Reference for Red Hat Enterprise Linux 6 provides further details about SystemTap Red Hat Enterprise Linux 7 SystemTap Tapset Reference The SystemTap Tapset Reference for Red Hat Enterprise Linux 5 provides further details about SystemTap See Also Section A 7 Changes in Dyninst provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of Dyninst and the version distributed in the previous release of Red Hat Developer Toolset Chapter 1 Red Hat Developer Toolset provides an overview of Red Hat Developer Toolset and more information on how to install iton your system Chapter 11 SystemTap provides an introduction to SystemTap and explains how to use it to monitor the activities of a running system Chapter 12 Valgrind explains how to use Valgrind to profile applications and detect memory errors and memory management problems such as the use of uninitialized memory improper allocation and freeing of memory and the use of improper arguments in system calls Chapter 13 OProfile explains how to use OProfile to determine which sections of code consume the greatest amount
186. s not decrease the performance of programs that do not use transactions nor the performance of nontransactional code except due to the normal kinds of interference by concurrent threads that use the same resources such as the CPU Transactional memory support in GCC and 1ibitnm is still experimental and both the ABI and API could change in the future if this is required due to the evolution of the specification of the language constructs or due to implementation requirements Note that when executing applications built with the fgnu tm command line option it is currently a prerequisite to also have the appropriate version of the Libitm so 1 shared library installed B 2 1 1 4 Architecture specific Options Red Hat Developer Toolset 3 0 is only available for Red Hat Enterprise Linux 6 and 7 for the 64 bit Intel and AMD architectures Consequently the options described below are only relevant to these architectures Optimization for several processors is now available through the command line options described in Table B 1 Processor Optimization Options Option Description march core2 and mtune core2 Optimization for Intel Core 2 processors march corei7 and mtune corei7 Optimization for Intel Core 13 15 and i7 processors march corei7 avx and mtune corei 7 Optimization for Intel Core 13 15 and i7 avx processors with AVX Option Description march core avx 1 Optimization for the Intel processor code named Ivy Bri
187. s on gdb Value objects to access structure elements A new attribute name has been added for gdb Type objects Valid Python operations on gdb Value objects representing structs or classes now invoke the corresponding overloaded operators if available A new feature Xmethods has been added to the Python API Xmethods are additional methods or replacements for existing methods of a C class This feature is useful for those cases wherea method defined in C source code could be inlined or optimized out by the compiler making it unavailable to GDB New Commands Anumber of new commands have been added Anew command catch rethrow has been added This command works like the catch throw command but it only catches re thrown exceptions Anew command maint check psymtabs has been added This command has been renamed from the old maint check symtabs It is used for checking the consistency of partial symbol tables Anew command maint check symtabs has been added It performs consistency checks on full symbol tables Anew command maint expand symtabs has been added It is used for expanding full symbol tables that match an optional regular expression Anew command show configuration has been added The command displays the details of the configuration options with which GDB was built This command is the equivalent of the configuration command line option Anew command remove symbol file has been added It can be us
188. se this as the default and do not ask again check box to prevent Eclipse from displaying this dialog box the next time you run this development environment When you are done click the OK button to confirm the selection and proceed with the startup 2 2 1 Using the Red Hat Developer Toolset Toolchain To use the Red Hat Developer Toolset version of Eclipse with support for the GNU Compiler Collection and binutils from Red Hat Developer Toolset make sure that the devtoolset 3 toolchain package is installed and run the application as described in Section 2 2 Using Eclipse Red Hat If you are working on a project that you previously built with the Red Hat Enterprise Linux version of the GNU Compiler Collection make sure that you discard all previous build results To do so open the project in Eclipse and select Project Clean from the menu 2 2 2 Using the Red Hat Enterprise Linux Toolchain To use the Red Hat Developer Toolset version of Eclipse with support for the toolchain distributed with Red Hat Enterprise Linux change the configuration of the project to use absolute paths to the Red Hat Enterprise Linux system versions of gcc g and as To configure Eclipse to explicitly use the Red Hat Enterprise Linux system versions of the tools for the current project complete the following steps 1 In the C C perspective choose Project Properties from the main menu bar to open the project properties 2 In the menu on the
189. set Name Description Memcheck Detects memory management problems by intercepting system calls and checking all read and write operations Cachegrind Identifies the sources of cache misses by simulating the level 1 instruction cache 11 level 1 data cache D1 and unified level 2 cache L2 Callgrind Generates a call graph representing the function call history Helgrind Detects synchronization errors in multithreaded C C and Fortran programs that use POSIX threading primitives DRD Detects errors in multithreaded C and C programs that use POSIX threading primitives or any other threading concepts that are built on top of these POSIX threading primitives Massif Monitors heap and stack usage 12 1 Installing Valgrind In Red Hat Developer Toolset Valgrind is provided by the devtoolset 3 valgrind package and is automatically installed with devtoolset 3 perftools If you intend to use Valgrind to profile parallel programs that use the Message Passing Interface MPI protocol also install the devtoolset 3 valgrind openmpi package by typing the following ata shell prompt as root yum install devtoolset 3 valgrind openmpi For detailed instructions on how to install Red Hat Developer Toolset and related packages to your system see Section 1 5 Installing Red Hat Developer Toolset Note that if you use Valgrind in combination with the GNU Debugger it is recommended that you use the version of GDB that is included
190. sing the runtime dyninst or dyninst parameter to stap has had a number of compatibility and performance improvements added The quality and detail of error messages have been greatly improved The improvements include colorization manual page cross referencing and suggestions for correcting typing mistakes The prologue analysis for placing function entry probes has been improved A function callee typeof probe for probing outgoing calls from given functions has been introduced Many new functions have been added to the tapset library The following new features are only available on Red Hat Enterprise Linux 7 systems SecureBoot support via a stap server has been extended with key generation and module signing User Guide Support has been added for probing virtual machines from the host without a network The probing requires a minimal runtime installed within the virtual machine which communicates through the virtio serial device Support has been added for using gnu_debugdata symbol tables in base executables to resolve certain probe symbols or addresses without the need for full debuginfo Incompatibility problems with old scripts can be resolved using the backward compatibility option compatible version where version is the version of SystemT ap for which the script was written B 9 Changes in Valgrind Red Hat Developer Toolset 3 0 is distributed with Valgrind 3 9 which provides a number of bug fix
191. strace tt pwd 19 43 28 011815 execve pwd pwd 36 vars O 19 43 28 012128 brk 0 0xcd3000 19 43 28 012174 mmap NULL 4096 PROT_READ PROT_WRITE MAP_PRIVATE MAP_ANONYMOUS 1 Ox 7fc869Cb0000 19 43 28 012427 open etc ld so cache O_RDONLY 3 19 43 28 012446 fstat 3 st_mode S_IFREG 0644 st_size 61239 0 19 43 28 012464 mmap NULL 61239 PROT_READ MAP_PRIVATE 3 0 Ox7fc869cal1000 19 43 28 012483 close 3 0 19 43 28 013410 exited with 8 2 4 Displaying a SUmmary To display a summary of how much time was required to execute each system call how many times were these system calls executed and how many errors were encountered during their execution run the strace utility with the c command line option scl enable devtoolset 3 strace c program argument Example 8 4 Displaying a Summary Consider an executable file named 1sbl1k To run the strace utility on this file and display a trace summary type scl enable devtoolset 3 strace c lsblk gt dev null time seconds usecs call calls errors syscall 80 88 0 000055 1 106 16 open 197127 0 000013 0 140 munmap 0 00 0 000000 0 148 read 0 00 0 000000 0 1 write 0 00 0 000000 0 258 close 0 00 0 000000 0 37 2 stat 100 00 0 000068 1790 35 total 8 3 Additional Resources A detailed description of strace and its features is beyond the scope of this book For more information see the resources listed below
192. strace 4 8 A debugging tool to monitor system calls that a program uses and signals it receives memsto mp 0 1 5 A debugging tool to identify calls to library functions with overlapping memory regions that are not allowed by various standards SystemTap 20 A tracing and probing tool to monitor the activities of the entire system without the need to instrument recompile install and reboot Valgrind 3 10 1 An instrumentation framework and a number of tools to profile applications in order to detect memory errors identify memory management problems and report any use of improper arguments in system calls User Guide Name Version Description OProfile 0 9 9 A system wide profiler that uses the performance monitoring hardware on the processor to retrieve information about the kernel and executables on the system Dyninst 8 2 1 A library for instrumenting and working with user space executables during their execution a If you intend to develop applications for Red Hat JBoss Middleware or require support for OpenShift Tools itis recommended that you use Red Hat JBoss Developer Studio in Red Hat Enterprise Linux in two important respects 1 Red Hat Developer Toolset can be used on multiple major and minor releases of Red Hat 2 Unlike Technology Preview compilers and other tools shipped in earlier Red Hat Enterprise Linux Red Hat Developer Toolset is fully supported under Red Hat Enterprise Linux Subscription Level Agreements is
193. t devtoolset 3 eclipse mylyn devtoolset 3 eclipse pde devtoolset 3 eclipse remote devtoolset 3 eclipse tests devtoolset 3 eclipse linuxtools devtoolset 3 eclipse changelog l devtoolset 3 eclipse gcovl2l Chapter 2 Eclipse Description The C C Development Tooling CDT which provides features and plug ins for developmentin C and C The Eclipse Modeling Framework EMF which allows you to build applications based on a structured data model The Graphical Editing Framework GEF which allows you to create a rich graphical editor from an existing application model The Remote System Explorer RSE framework which allows you to work with remote systems from Eclipse JGit a Java implementation of the Git revision control system EGit a team provider for Eclipse that provides features and plug ins for interaction with Git repositories Mylyn a task management system for Eclipse The Plugin Development Environment for developing Eclipse plugins The Remote Services plug in which provides an extensible remote services framework Eclipse tests A meta package for Linux specific Eclipse plug ins The ChangeLog plug in which allows you to create and maintain changelog files The GCov plug in which integrates the GCov test coverage program with Eclipse The Gprof plug in which integrates the Gprof performance analysis utility with Eclipse The Man Page plug in which allows you to view manual pages i
194. t 3 dwz option file_name Note that you can execute any command using the scl utility causing it to be run with the Red Hat Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent This allows you to run a shell session with Red Hat Developer Toolset dwz as default scl enable devtoolset 3 bash To verify the version of dwz you are using at any point type the following at a shell prompt which dwz Red Hat Developer Toolset s dwz executable path will begin with opt Alternatively you can use the following command to confirm that the version number matches that for Red Hat Developer Toolset dwz dwz v 6 3 Additional Resources A detailed description of dwz and its features is beyond the scope of this book For more information see the resources listed below Installed Documentation 37 User Guide dwz 1 The manual page for the dwz utility provides detailed information on its usage To display the manual page for the version included in Red Hat Developer Toolset type scl enable devtoolset 3 man dwz See Also 38 Chapter 1 Red Hat Developer Toolset provides an overview of Red Hat Developer Toolset and more information on how to install iton your system Chapter 3 GNU Compiler Collection GCC provides information on how to compile programs written in C C and Fortran Chapter 4 binutils explains how to use the binutils a collection of binary tools
195. t Developer Toolset 3 1 User Guide Revision 0 0 17 Tue 10 Mar 2015 Robert Kr tk Release of Red Hat Developer Toolset 3 1 Beta User Guide Revision 0 0 16 Thu 13 Nov 2014 Robert Kr tk Release of Red Hat Developer Toolset 3 0 User Guide with minor post GA fixes Revision 0 0 14 Thu 30 Oct 2014 Robert Kr tk Release of Red Hat Developer Toolset 3 0 User Guide Revision 0 0 10 Tue 07 Oct 2014 Robert Kr tk Release of Red Hat Developer Toolset 3 0 Beta 2 User Guide Revision 0 0 8 Tue Sep 09 2014 Robert Kr tk Release of Red Hat Developer Toolset 3 0 Beta 1 User Guide Index ABI compatibility ABI Compatibility addr2line featur res New Featu res application binary interface see ABI ar overview binutils as see GNU assembler assembling see GNU assembler binutils docu mentation Additional Resources 142 Appendix C Revision History version About Red Hat Developer Toolset binutils C programming language compiling Using the C Compiler Preparing a Program for Debugging C programming language compatibility aes Compatibility C 11 see GNU Compiler Collection c filt overview binutils C11 see GNU Compiler Collection Cachegrind overview Valgrind Callgrind overview Valgrind compatibility GNU Compiler Collection Language Compatibility Compatibility Changes Fortran compiling see GNU Compiler Collection debugging see GNU Debugger Developer Toolset see Red
196. t file faster Note that this feature is already present in Red Hat Enterprise Linux 6 1 and later The watch command has been adapted to accept location as an optional argument Two new special values can now be used when specifying the current search path for libthread_db sdir represents the default system locations of shared libraries and pdir stands for the directory with the Libthread that is used by the application The info macro command now accepts all and as valid options To display a function parameter s entry value that is the value at the time of function entry the suffix entry can be added to the parameter GDB now displays entry values in backtraces if available The watch command now accepts mask mask_value as an argument This can be used to create masked watchpoints The info os command has been changed and can now display information on several objects managed by the operating system in particular The info os procgroups command lists process groups The info os files command lists file descriptors The info os sockets command lists internet domain sockets Theinfo os shm command lists shared memory regions The info os semaphores command lists semaphores The info os msg command lists message queues Theinfo os modules command lists loaded kernel modules GDB now has support for Static Defined Tracing SDT probes Currently the only implemented back end is for SystemTap probes the sys sdt h hea
197. tion C support GNU C Compiler GNU Debugger documentation Additional Resources GNU linker documentation Additional Resources gprof overview binutils GSS see Global Support Services Helgrind overview Valgrind help Global Support Services Contacting Global Support Services Id see GNU linker linking see GNU linker Itrace Massif docu mentation Ad ditional Resou rces Memcheck overview Valgrind memstomp nm objcopy objdump ocount docu mentation Ad ditional Resources featu res New Featu res overview OProfile opannotate overview OProfile oparchive overview OProiile opcontrol overview OProfile Appendix C Revision History 147 User Guide usage Using OProfile opgprof overview OProfile Apap overview OProfile opimport overview OProfile opjitconv overview OProfile opreport overview OProfile OProfile docu mentation Additional Resources oprofiled overview OProfile ranlib readelf features New Features Red Hat Developer Toolset pel nn d Compatibility 148 Appendix C Revision History Red Hat Enterprise Linux documentation Additional Resources Accessing Red Hat Product Documentation Red Hat Subscription Management subscription Using Red Hat Subscription Management RHN Classic subscription Using RHN Classic scl see Software Collections size overview binutils Software
198. to inspect and manipulate object files and binaries Chapter 5 elfutils explains how to use elfutils a collection of binary tools to inspect and manipulate ELF files Part IV Debugging Tools Part IV Debugging Tools 39 Chapter 7 GNU Debugger GDB The GNU Debugger commonly abbreviated as GDB is a command line tool that can be used to debug programs written in various programming languages It allows you to inspect memory within the code being debugged control the execution state of the code detect the execution of particular sections of code and much more Red Hat Developer Toolset is distributed with GDB 7 8 2 This version is more recent than the version included in Red Hat Enterprise Linux and the previous release of Red Hat Developer Toolset and provides some enhancements and numerous bug fixes 7 1 Installing the GNU Debugger In Red Hat Developer Toolset the GNU Debugger is provided by the devtoolset 3 gdb package and 7 2 Preparing a Program for Debugging Compiling Programs with Debugging Information To compile a C program with debugging information that can be read by the GNU Debugger make sure the gcc compiler is run with the g option To do so on the command line use a command in the following form scl enable devtoolset 3 gcc g o output_file input_file Similarly to compile a C program with debugging information run scl enable devtoolset 3 g g o output_file input_file E
199. uments For instance users that instantiate standard library components like std vector with hidden user defined types such as struct my_hidden_struct can now expect hidden visibility for std vector lt my_hidden_struct gt symbols As a result users that compile with the fvisibility hidden command line option should be aware of the visibility of types included from the library headers used If the header does not explicitly control symbol visibility types from those headers will be hidden along with instantiations that use those types For instance consider the following code include lt vector gt template std vector has default Visibility include lt ctime gt struct tm has hidden visibility template class std vector lt tm gt instantiation has hidden visibility One approach to adjusting the visibility of a library header lt foo h gt is to create a forwarding header on the I include path consisting of the following pragma GCC visibility push default include_next lt foo h gt pragma GCC visibility push User defined Literal Support When compiling C with the std c 11 c 0x gnu 11 gnu 0x command line option GCC 4 7 0 and later unlike older versions supports user defined literals which are incompatible with some valid ISO C 03 code In particular white space is now needed after a string literal before something that could be a valid user defined literal Consider the following code const c
200. ute and with a non constant length type parameter are now supported Support has been added for procedure pointer function results and procedure pointer components including PASS Support has been added for allocatable scalars experimental DEFERRED type bound procedures and the ERRMSG argument of the ALLOCATE and DEALLOCATE statements The ALLOCATE statement now supports type specs and the SOURCE argument Rounding ROUND RZ for output is now supported The INT_FAST 8 16 32 64 128 _T format for ISO_C_BINDING intrinsic module type parameters is now supported Annandiv R Channac in VJarcinn 2 A Appendix B Changes in Version 3 0 OPERATOR and ASSIGNMENT are now allowed as GENERIC type bound procedures i e as type bound operators Support for unlimited polymorphic variables C LASS has been added Non constant character lengths are not yet supported B 2 1 3 4 Fortran 2003 Compatibility Extensible derived types with type bound procedure or procedure pointer with P ASS attribute now have to use CLASS in line with the Fortran 2003 standard the workaround to use TYPE is no longer supported B 2 1 3 5 Fortran 2008 Features Anew command line option std f2008ts has been added This option enables support for programs that conform to the Fortran 2008 standard and the draft Technical Specification TS The DO CONCURRENT construct is now supported This construct can be used to specify that i
201. view of Red Hat Developer Toolset and more information on how to install iton your system Chapter 2 Eclipse provides a general introduction to the Eclipse development environment and describes how to use it with the tools from Red Hat Developer Toolset Chapter 4 binutils explains how to use the binutils a collection of binary tools to inspect and manipulate object files and binaries Chapter 5 elfutils explains how to use elfutils a collection of binary tools to inspect and manipulate ELF files Chapter 6 dwz explains how to use dwz to optimize DWARF debugging information contained in ELF shared libraries and ELF executables for size Chapter 7 GNU Debugger GDB provides information on how to debug programs written in C C and Fortran Chapter 4 binutils binutils is a collection of various binary tools such as the GNU linker GNU assembler and other utilities that allow you to inspect and Mala object files and binaries See Table 4 1 Tools distributed with the Red Hat Developer Toolset version of binutils Red Hat Developer Toolset is distributed with binutils 2 24 This version is more recent than the version included in Red Hat Enterprise Linux and provides bug fixes and enhancements including support for the AVX 512 512 bit Advanced Vector Extensions Table 4 1 Tools Included in binutils for Red Hat Developer Toolset Name Description addr2line Translates addresses into file names and line
202. xample 7 1 Compiling a C Program With Debugging Information Consider a source file named fibonacci c that has the following contents include lt stdio h gt include lt limits h gt int main int argc char argv unsigned long int a 0 unsigned long int b 1 unsigned long int sum while b lt LONG_MAX printf ld b sum a b a b b sum return 07 To compile this program on the command line using GCC from Red Hat Developer Toolset with debugging information for the GNU Debugger type scl enable devtoolset 3 gcc g o fibonacci fibonacci c This creates a new binary file called fibonacci in the current working directory Installing Debugging Information for Existing Packages To install debugging information for a package thatis already installed on the system type the following ata shell promptas root debuginfo install package_name Note that the yum utils package must be installed for the debuginfo install utility to be available on your system Example 7 2 Installing Debugging Information for the glibc Package To install debugging information for the glibc package type debuginfo install glibc Loaded plugins product id refresh packagekit subscription manager gt Running transaction check gt Package glibc debuginfo x86_64 0 2 12 1 47 e16_2 5 will be installed 7 3 Running the GNU Debugger To run the GNU Debugger on a program you want to debu
203. ying to execute an undefined GDB MI command now provides a variable named code whose content is the undefined command error code Support for this feature can be verified by using the Llist features command which should contain the undefined command error code item The trace save command can now optionally save trace buffer in the Common Trace Format Anew command dprintf insert has been added It sets a dynamic printf breakpoint The data list register values command now accepts an optional skip unavailable option When used only available registers are displayed Anew command trace frame collected has been added It returns objects register names trace state variables memory ranges and computed expressions that have been collected in a trace frame There is no corresponding GDB command The stack list locals stack list arguments and stack list variables commands now accept the skip unavailable option When used only available locals or arguments are displayed The exec run command now accepts the optional start option When used the command follows the same semantics as the start command stopping the program s execution at the start of its main subprogram Support for this feature can be verified by using the list features command which should contain the exec run start option item New commands catch assert and catch exceptions have been added The commands insert catchpoints stopping the progra
204. you are using at any point type the following at a shell prompt which g Red Hat Developer Toolset s g executable path will begin with opt Alternatively you can use the following command to confirm that the version number matches that for Red Hat Developer Toolset g g V Important Some newer library features are statically linked into applications built with Red Hat Developer Toolset to Support execution on multiple versions of Red Hat Enterprise Linux This adds a small additional security risk as normal Red Hat Enterprise Linux errata would not change this code If the need for developers to rebuild their applications due to such an issue arises Red Hat will signal this via a security erratum Developers are strongly advised not to statically link their entire application for the same reasons Example 3 3 Compiling a C Program on the Command Line Consider a source file named hello cpp with the following contents include lt iostream gt uSing namespace std int main int argc char argv cout lt lt Hello World lt lt endl return J To compile this source code on the command line by using the g compiler from Red Hat Developer Toolset type scl enable devtoolset 3 g 0 hello hello cpp This creates a new binary file called hello in the current working directory 25 3 2 3 Running a C Program When g compiles a program it creates an executable binary file T

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