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ST200 Micro Toolset User Manual

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1. 136 Intrinsic functions summary Intrinsic Purpose ST200 name int32 maz int32 int32 C optimization __maxw int16_max_int16_int16 C optimization _ maxh uint32_ max uint32_uint32 C optimization maxuw _ uintl6 max uintl16_uintl6 C optimization _ maxuh Table 37 Maximum intrinsics Intrinsic Purpose ST200 name _ int32 abs _int32 C optimization __absw __int16_abs_int16 C optimization __absh __int32_absc_int32 ETSI L_abs __abscw __int16_absc_int16 ETSI abs_s __absch Table 38 Absolute value intrinsics Intrinsic Purpose ST200 name int32_dist_int32_int32 DSP operator __distw int16_dist_int16_int16 DSP operator __disth uint32_dist_uint32_uint32 DSP operator __distuw uint16_dist_uint16_uint16 DSP operator _ distuh Table 39 Absolute distance intrinsics y STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Intrinsic functions summary 137 int32 shrr int32 uint16 ETSIL_shrr sa int16_shrr_int16_uint16 ETSI shr_r __shrrh Table 40 Right shift intrinsics a To achieve the ETSI operator a combination of the intrinsic functions are required For example L_shl in Table 47 is implemented in terms of__shlcw and __shrw Intrinsic Purpose ST200 name int32 shlc_int32_uint16 ETSI L_shl __shlcw int16_shlc_int16_uint16 ETSI shi __shlch Table 41 Left shift intrinsics Int
2. INLINE dfe Allow dead function elimination Default is on INLINE specfile filename Specifies a filename containing inlining options Default is none Table 26 Standalone inlining options In addition to these options the following option may be of interest when building a large body of inline functions which is not recommended and may adversely affect performance Option Description OPT 0limit 0 n Functions larger than size n are not optimized Default is 3000 Specifying O removes any limit but may lead to a very long compile time Table 27 Option changing inlining behavior 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H Inlining 5 2 3 5 2 4 5 2 4 1 5 2 4 2 PRELIMINARY DATA 63 Extern inline functions If both inline and extern are specified in a function definition then the definition is used only for inlining The function is never compiled on its own not even if its address is referred to explicitly The address becomes an external reference as if the function had only been declared but not defined This combination of inline and extern has almost the same effect as a macro The way to use it is to put a function definition in a header file with these keywords and put another copy of the definition lacking inline and extern in a library file The definition in the header file will cause most calls to the function to be i
3. 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA ST200 Micro Toolset interface 7 Command 1 causes the following steps to be executed lt tools dir gt bin st200cc st200cc driver lt tools dir gt lib cpp lt cpp_flags gt filel c filel i C preprocessor lt tools dir gt lib cmplrs lt C compiler gt lt C Compiler flags gt filel i filel s C compiler lt tools dir gt bin st200as lt st200as_flags gt filel s filel o ST200 Assembler Command 2 causes the following steps to be executed lt tools dir gt bin st200cc st200cc driver lt tools dir gt lib cpp lt cpp_flags gt file2 c file2 i C preprocessor lt tools dir gt lib cmplrs lt C compiler gt lt C Compiler flags gt file2 i file2 s C compiler lt tools dir bin st200as lt st200as_flags gt file2 s file2 o ST200 Assembler Command 3 causes the following steps to be executed lt tools dir gt bin st200cc st200cc driver lt tools dir gt bin st2001d lt st2001d_flags gt ST200 linker lt tools dir gt 1ib st220 le bare crt1 o ST200 startup files lt tools dir gt 1lib st220 le bare crti o ST200 startup files lt tools dir gt 1ib st220 le bare crtbegin o ST200 startup files filel o file2 o Application objects lt tools dir gt 1lib st220 le bare libc a ST200 C libraries run time lt tools dir gt lib st220 le bare libgcc a arithmetic library lt tools dir gt 1lib st220 le bare crtn o
4. Table 1 Input Names conventions Extension Convention Produced by option s S Assembly language output file S 0 Object file c Table 2 Output Names conventions The final executable file does not need to have a specific file extension If no output file name is specified through the o option the executable generated is named a out Examples st200cc file c generates the executable a out st200cc file c o file u generates the executable file u 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Command line options 11 2 2 Command line options 2 2 1 Getting help If the compiler driver is given the help option it displays the list of available options and then terminates Additionally the help option can be followed by an additional keyword separated from the help option by a colon All entries matching the keyword are displayed on the standard output for example st200cc help W This command displays all options containing the W string In this example all options related to the emission of compiler warnings will be listed 2 2 2 Overall options The options in Table 3 control the type of processing performed by st200cc and the output it generates for example an executable an object file an assembler file a pre processed file an archive or a dependency list Output files produced by these option default to lt original file name gt lt
5. Table 21 Predefined macros The C standard guarantees that the _ cplusplus symbol is never defined when compiling C source code and the C standard guarantees that __ cplusplus is defined when compiling C source code ADCS 7508723H STMicroelectronics 9j ST200 Micro Toolset User Manual PRELIMINARY DATA 38 GNU C language extensions 3 5 GNU C language extensions 3 5 1 Extensions to the C language 3 5 1 1 C language extensions supported in C The following C language extensions are supported in C e alignof e typeof e case ranges e label as values 3 5 1 2 C specific extensions Minimum and maximum operators a lt b is the minimum returning the smaller of the numeric values a and b a gt b is the maximum returning the larger of the numeric values a and b 3 5 2 Variable functions and type attributes 3 5 2 1 C language attributes supported in C The following C attributes are supported in the C context Placement and layout attributes e section e weak e alias e align e pack e constructor e destructor hi ST Microelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA GNU C asm statement 39 3 5 2 2 Note 3 5 3 3 6 3 7 Optimization attributes e malloc e noreturn C specific attributes Initialization priority This feature is unsupported in the current release Support attribute init priority n
6. for controlling the order of initialization of file scope objects Where nis a number representing the priority of that object File scope objects are initialized in order from the lowest number highest priority to the highest lowest priority Built ins The following C language built ins are supported in C e builtin constant_p e _ builtin expect GNU C asm statement The GNU asm statement is supported as in the C compiler Standard Template Libraries STL support This support is based on libstdc v3 you can consult the documentation online at the following site http gcc gnu org onlinedocs libstdc documentation html The very latest user documentation is available through http gcc gnu org onlinedocs libstdc libstdc html USERS 3 4 index html I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 40 PRELIMINARY DATA Standard Template Libraries STL support The full C standard library is supported excepted for the lt complex gt header and limited to the underlying C library support limitations no wide char support but augmented with the long long support The library includes the GNU STL extensions and the backward compatibility headers 3 7 1 Standard headers status All the following standard headers are supported unless otherwise stated hy ST200 Micro Toolset User Manual Header files lt algorith
7. PRELIMINARY DATA ST200 Cross Development Manual ADCS 7521642 This manual describes the cross development tools and platforms ST200 Run time Architecture Manual ADCS 7521848 This manual describes the common software conventions for the ST200 processor runtime architecture OS21 for ST200 User Manual ADCS 7410372 This manual describes the use of OS21 on ST200 platforms It describes how specific ST200 facilities are exploited by the OS21 API It also describes the OS21 board support packages for ST200 platforms ST220 Core and Instruction Set Architecture ADCS 7395369 This manual describes the architecture and the instruction set of the ST220 core as used by STMicroelectronics ST231 Core and Instruction Set Architecture ADCS 7645929 This manual describes the architecture and the instruction set of the ST231 core as used by STMicroelectronics STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA KV Conventions used in this guide General notation The notation in this document uses the following conventions e sample code keyboard input and file names e variables and code variables e code comments e screens windows and dialog boxes e instructions Hardware notation The following conventions are used for hardware notation e REGISTER NAMES and FIELD NAMES e PIN NAMES and SIGNAL NAMES Software notation Syntax definitions are presented in a modified Backus Nau
8. in profile mode daVinci dump is not accessible for TRG and LTRG algorithms e start symbol s is not a function ignored warning start symbol given with begin option is not a function e start symbol s is not global ignored warning start symbol given with begin option is static e ignored symbol s is not a function ignored warning ignored symbol given with ignore option is not a function e ignored symbol s is not global ignored warning ignored symbol given with ignore option is static e overflow during normalization of static call graph warning during the normalization of static call graph overflow has been detected A re normalization is done to avoid overflow in next phases e Can t apply this algorithm placement for static estimation take PH warning TRG or LTRG algorithm are not accessible in static mode e Cannot find s in symbol table n warning a symbol given in a 1ly input file cannot be found in the symbol table e Cannot find s with index d warning warning a symbol given in a 1y input file cannot be found in the symbol table with this index case of several static functions with the same name e Can t open link order file s warning input ordering file 1y cannot be accessed No reordering is done just copying e bfd error s error input object file is not a bfd object e s No symbols warning cannot fin
9. y Y PRELIMINARY DATA ST200 VLIW Series ST200 Micro Toolset User Manual Last updated 15 June 2005 ky ST Microelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA Issued by the MCDT Documentation Group on behalf of STMicroelectronics Information furnished is believed to be accurate and reliable However STMicroelectronics assumes no responsibility for the conseguences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics Specifications mentioned in this publication are subject to change without notice This publication supersedes and replaces all information previously supplied STMicroelectronics products are not authorized for use as critical components in life support devices or systems without the express written approval of STMicroelectronics The ST logo is a registered trademark of STMicroelectronics All other names are the property of their respective owners The ST200 series cores are based on technology jointly developed by Hewlett Packard Laboratories and STMicroelectronics Microsoft and Windows are registered trademarks of Microsoft Corporation in the United States and or other countries Solaris is a trademark of Sun Microsystems Inc in the US and other countries Cygwin and Insight are trademarks
10. 113 expressions 107 core 22 25 190 193 core x 22 cpp 98 105 111 passing option to 21 vararg macro 104 CVG dump 170 Cygwin 3 D davinci 170 dD 12 Ddef 12 dead code elimination 151 debug information 2 16 152 ADCS 7508723H 199 default visibility 114 destructor 38 113 dM 12 dN 12 documentation suite notation xv dumpversion 11 DWARF2 2 16 dynamic_cast 43 E E 11 12 EB 22 25 EL 22 25 ELF 2 97 endianness 2 5 22 25 end of file 179 enum 110 escape character 110 etsitom h 130 etsitost220 h 130 exit 113 114 F f no Jaccess control 34 f no check new 34 f no dismissible load 19 f no Jelide constructors 35 f no Jexceptions 34 37 f no for scope 35 f no gnu keywords 35 f no limplicit templates 34 f no permissive 35 f no rtti 34 f nolsigned bitfields 18 f no strict aliasing 17 71 75 f no Junroll loops 17 I STMicroelectronics ST200 Micro Toolset User Manual PRELIMINARY DATA 200 f no Junsigned bitfields 18 f no verbose asm 19 f no zero initialized in bss 19 fb 17 fb create 17 fcheck new 44 fdiagnostics show location 35 fenv h 28 ffixed reg 18 finstrument functions 16 81 83 float h 28 floating point 101 fmessage length 35 fno exceptions 31 44 fno rtti 43 format 115 format_arg 115 fpreprocessed 12 fsigned char 18 ftemplate depth 35 function calls 81 83 prototype 109 funsigned char 18 fvisibilit
11. ADCS 7508723H PRELIMINARY DATA Intrinsic functions summary 141 Intrinsic Purpose ST200 name uint16 bitnot uint16 uint16 DSP operator __bitnoth __uint16_bitval_uint32_uint16 DSP operator __bitvalw uint16_bitval_uint16_uint16 DSP operator __bitvalh int32 bitrev_uint16_int32 DSP operator _ bitrevw Table 49 Bit manipulation intrinsics Intrinsic Purpose ST200 name int32 inseg int32_int32 int32 DSP operator __inseqw int32 insne int32_int32_ int32 DSP operator __insnew int32_insgt_int32_int32_int32 DSP operator __insgtw int32 insge_int32_int32_int32 DSP operator _ insgew int32 inslt_int32_ int32 int32 DSP operator __insltw int32_insle_ int32_int32_int32 DSP operator __inslew __uint32_inseq_uint32_uint32_uint32 DSP operator __insequw __uint32_ insne uint32_ uint32 uint32 DSP operator __insneuw __uint32_insgt_uint32_uint32_uint32 DSP operator __insgtuw uint32_insge_uint32_uint32_uint32 DSP operator __insgeuw uint32 inslt_uint32_ uint32 uint32 DSP operator __insltuw __uint32_ insle uint32 uint32 uint32 DSP operator __insleuw Table 50 Viterbi intrinsics I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 142 Intrinsic functions summary Intrinsic Purpose ST200 name int32 mul int32 int
12. It is important to understand the principles behind the naming conventions because of the number of intrinsic functions that are available Understanding these principles relieves the need to remember specific names and enables the name of an intrinsic to be deduced from its specific operation The following sections expand on the type mapping and name conventions used in the intrinsics 1 Many of the standard algorithms in Wireless and Wireline communications such as GSM Global System for Mobile Telecommunications or AMR NB for UMTS Adaptive Multi Rate Narrow Band for UMTS encoders are provided by the ITU and ETSI as ANSI C code using 16 bits fractional arithmetic For the ITU refer to http www itu int or for the ETSI refer to http www etsi org To specify the fractional arithmetic model which is foreign to ANSI C a set of subroutines are used implementing basic fractional operations As these basic fractional operations are provided as ANSI C source codes an algorithm complying with the ITU or ETSI compiles on any ANSI C compiler It therefore requires little effort to compile and run the algorithm on any workstation or DSP However an efficient implementation on a DSP requires some modifications of the original code The st200cc compiler provides a set of intrinsics that help make these modifications as minor as possible c ST Microelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DAT
13. or a profile call graph Within the call graph nodes are procedures and weight of the edges is the number of calls estimated for a static call graph or based on the profile trace VCG XVCG dump By using the dump option binopt generates a XVCG Visualization of Compiler Graphs file which is sent to stdout Example binopt o myexe ly static icacheopt input myexe po dump output myexe op gt myexe dump or st200cc c 02 Wo dump o myexe gt myexe dump then xvcg myexe dump amp VCG XVCG USAAR Visualization Tool V 1 3 can be downloaded at http rw4 cs uni sb de sander html gsvcg1 html availability daVinci V2 1 dump When the davinci lt file gt option is used binopt generates a daVinci file in lt file gt 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA binopt 171 Example binopt o myexe ly static icacheopt input myexe po davinci myexe davinci output myexe op or st200cc c 02 Wo davinci myexe davinci o myexe then daVinci myexe davincig daVinci V2 1 can be downloaded at http www tzi de davinci 10 4 4 How to configure binopt To help binopt to better estimate the call graph of your final application a set of options are provided e icg lt file gt Cache call graph user configuration file In this file it is possible to add or remove edges of the estimated static call graphs Use binopt icgdum
14. page 86 This section documents a range of advanced IPA options that provide control over the optimizations performed 2 2 15 Symbol visibility specification The options fvisibility and mvisibility decl are provided to specify symbol visibility they are documented in Section 5 10 Symbol visibility specification on page 89 7 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Command line options 21 2 2 16 Sending options to a specific phase The w lt phase gt lt arg gt option passes the specified argument lt arg gt to a specific processing phase lt phase gt of st200cc Table 11 lists the different values of lt phase gt Value of phase Description Preprocessor cpp Compiler front end Assembler st200as Linker st2001d Binary optimizer tool binopt Table 11 Possible value for phase There must be a comma between the option W lt phase gt and the argument and no spaces Anything occurring after a space is treated as the next option to st200cc Also the argument is only passed to lt phase gt if lt phase gt is normally run from the specified command For example st200cc 03 Wo help a out This command executes the ICache optimizer which is enabled by the 03 option and the argument help is passed in Multiple arguments must be separated by commas with no spaces st200cc 03 Wo dump static a out Full details of binopt option
15. to assemble Each run of st200as produces an output file the object file If the source file is empty st200as produces a small empty object file The default output file name is a out but it may be renamed using the o option 11 3 2 Error and warning messages st200as may write warnings and error messages to the standard error file usually the terminal Warnings report assumptions made so that st200as can continue assembling a flawed program errors report grave problems that prevents the source program from being assembled Fatal error messages cause assembly to stop immediately Warning and error messages have the format where nnnis a line number file name nnn Message text hi ST Microelectronics ST200 Micro Toolset User Manual ADCS 7508723H 1971 PRELIMINARY DATA Revision history Version Date Comments I H June 05 Revised to incoprporate the R4 1 Toolset release G November 04 Revised to incorporate final comments for the R4 0 Toolset release F September 04 Revised to include IPA C and to reflect the R4 0 Toolset release E June 04 Revised to include ST231 and to reflect the ST200 R3 2 Toolset release D January 04 Minor update to clear review comments C October 03 Revised to reflect ST200 R3 1 Toolset release B June 03 Format changes to conform to style guide A May 03 First complete version submitted to ADCS ADCS 7508723H I STMicroelectronic
16. u c 3 EXTRACTBYTE twoasint 0 elif defined LITTLE ENDIAN u c 0 EXTRACTBYTE twoasint 0 u c 1 EXTRACTBYTE twoasint 1 u c 2 EXTRACTBYTE twoasint 2 u c 3 EXTRACTBYTE twoasint 3 Figure 4 Aliasing example writing through a character type page 1 of 2 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Data prefetching 75 else error Unknown endianness please define either BIG ENDIAN or LITTLE ENDIAN endif if u f 2 0f puts UNEXPECTED BEHAVIOUR else puts ANSI ALIASING BEHAVIOUR return 0 Figure 5 Aliasing example writing through a character type page 2 of 2 In this case the program always prints ANSI ALIASING BEHAVIOR regardless of the compiler and its optimization options Data prefetching The ST200 processor includes a data prefetching mechanism through a PFT instruction Prefetching data ahead ofits actual use enables some of the data cache miss penalties to be hidden Data cache miss cycles often account for a significant fraction of execution cycles The st200cc st200c compiler includes support for user and automatic data prefetch instructions e User data prefetch instructions are inserted in the C C code using a __builtin_ prefetch builtin e Automatic data prefetch is generated by the compiler at optimization level 03 using specific command line options described in
17. uid_t x return x 0 6 2 24 C comments C comment C comments are not recognized by the st200cc options ansi or traditional This is to avoid problems with constructs that contain the forward slash character For example x a b I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 110 Extensions to the C language family 6 2 25 Character ESC in constants The sequence Ye is recognized in string or character constants as an ASCII lt escape gt character char escape le char s tete 6 2 26 Inquiring on alignment of types or variables __alignof__ allows enquiries about how an object is aligned or the minimum alignment required by a type or variable struct foo int x char y int x _alignof_ double int b _alignof_ f y 6 2 27 Incomplete enum type An enum type can be defined without specifying its possible values typedef enum ee struct _s e p s enum _e red green blue black e X 6 2 28 Function names as strings GNU cc predefines two magic identifiers to hold the name of the current function The identifier FUNCTION holds the name of the function as it appears in the source The identifier PRETTY FUNCTION holds the name of the function pretty printed in a language specific fashion char here Function FUNCTION in file FILE 7 STMicroelectronics ST200 Micro Toolset U
18. 0112 Ox4A OX4a J J All the same value e Character constants There are two kinds of character constants A character stands for one character in one byte and its value may be used in numeric expressions String constants properly called string literals are potentially many bytes and their values may not be used in arithmetic expressions e Strings A string is written between double quotes It may not contain double quotes or null characters Special characters may be included in a string by using escape sequences as with C language programs Strings may be automatically null terminated in some contexts string asciiz gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 178 hi PRELIMINARY DATA Assembler syntax e Numerical constants The assembler distinguishes three types of numbers according to their storage requirements in the target machine Integers are numbers that fit into 32 bits an int in the C language Bignums are integers but they are stored in more than 32 bits Integers A binary integer is Ob or OB followed by zero or more of the binary digits either 0 or 1 An octal integer is 0 followed by zero or more of the octal digits chosen from 01234567 A decimal integer starts with a non zero digit followed by zero or more digits chosen from 1234567890 A hexadecimal integer is Ox or OX followed by one or more hexadecimal digits chosen from 01
19. GNU C language parser and implements state of the art compiler optimizations Thanks to this GNU C language parser the st200cc compiler is closely compatible with the GNU C compiler both at the driver level and on C language extensions GNU Compiler Collection project http www gnu org software gcc gcc html The processor independent compiler optimizations available in the st200cc compiler are mostly inherited from the Open64 project hosted on SourceForge http open64 sourceforge net Other compiler optimizations that are specific to the ST200 family of processors were developed by STMicroelectronics at the CMG Compilation and Simulation Expertise center These include e the exploitation of the ST200 SELECT instruction e aggressive instruction selection including mapping of the user boolean variables to the branch registers e instruction scheduling e software pipelining of the inner loops e compiler intrinsics and builtins support iy STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 1 2 7 PRELIMINARY DATA ST200 C compiler e reordering of object code to minimize instruction cache conflicts e dead code and dead data elimination e automatic generation of prefetch instructions e profiling feedback optimization e interprocedural analysis optimization The binary image can be executed on an ST220 or ST231 hardware target or by using st200gdb The binary format used for the image is E
20. Incomplete enum type 110 6 2 28 Function names as strings 110 6 3 Attributes 111 6 3 1 Placement and layout 111 6 3 2 Optimization 114 6 3 3 Visibility attributes 114 6 3 4 Miscellaneous attributes 115 6 3 5 Built ins 116 7 GNU ASM 119 7 1 Introduction 119 7 1 1 Syntax 119 7 1 2 Assumptions 120 7 1 3 Volatile 121 7 1 4 Scheduling considerations 121 7 1 5 Restrictions 122 7 1 6 Example 122 8 Intrinsic functions 123 8 1 Introduction 123 8 1 1 Rationale 123 8 1 2 Models 123 8 2 Naming intrinsics 124 8 2 1 Naming scheme 124 8 2 2 Building intrinsic names 125 8 3 Using intrinsics from C C 130 8 3 1 Include files 130 8 4 Understanding intrinsic models 133 8 4 1 Understanding fundamentals operators 133 8 4 2 Understanding models 134 7 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H 8 5 8 6 8 7 PRELIMINARY DATA Intrinsic functions summary 8 5 1 Functions ST231 intrinsics Division and modulus built ins 9 Compiler bugs 9 1 9 2 9 3 9 4 9 5 9 6 Introduction Identifying a compiler bug 9 2 1 9 2 2 Category 1 Category 2 Checks performed by user Work around Reporting a compiler bug Known bugs and limitations 10 ICache dead code optimization 10 1 Introduction 10 2 10 3 ADCS 7508723H 10 1 1 How it works 10 1 2 Synopsis 10 1 3 Cache files st200cc options 10 2 1 Other options 10 2 2 Default behavior 10 2 3 Option combination
21. See O0 to 03 and Os symbol visibility 89 95 techniques 59 86 OS 19 190 Os 16 OS21 21 P P 12 pack 38 packed 111 112 path 6 133 pedantic 13 15 98 pedantic error 13 pft 117 pg 16 prefetching 75 80 117 preprocessor See cpp printf 115 profiling 80 profiling feedback 83 85 protected visibility 115 R r 161 162 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA restrict 13 27 rtti 43 run application See st200run run time environment selecting 21 libraries ICache optimization 161 S S 11 scanf 115 section 38 111 SIGABRT 44 silicon 190 sizeof 106 soc x 22 st200ar 5 st200as 1 4 5 7 175 194 bundles 182 directives 187 191 expressions 181 182 operands 183 184 operations 185 187 passing options to 21 symbols 179 syntax 176 191 st200c 5 31 command line 32 36 exceptions 44 file types 32 GNU asm 39 GNU language extensions 38 invoking 32 limitations 31 46 new 44 predefined macros 36 standard template libraries 39 43 st200cc 1 4 5 bugs 147 149 ADCS 7508723H 203 command line 2 5 examples 6 9 10 ICache optimization examples 153 163 front end 21 input files 10 interfaces 4 invoking 9 output files 10 profiling feedback 83 86 reporting a bug 147 149 st200gdb 2 4 6 8 st200gprof 80 st200ld 1 4 5 7 9 32 112 boot and target files 22 compile without link 11 ICache optimization 151 154 156 157 160 163
22. To compile on a workstation with a generic compiler for instance gcc on Solaris or Linux you will have to include lt tools dir gt host imodels in your include search path use the I compiler option to add lt tools dir gt host imodels imodels c to your source files return _ swapbw x When compiled with the st200ce compiler the following code provides maximum efficiency for the ST200 target it can be compiled for any other target and automatically guarantees the same execution semantics With the st200cc compiler an application using this file swapb c can be compiled without modification apart from defining the toolset installation path st200cc swapb c other files c o main u STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Understanding intrinsic models 133 Note 8 4 8 4 1 With a gnu gce compiler on Unix gcc I lt tools dir gt include I lt tools dir gt host imodels lt tools dir gt host imodels imodels c swapb c other files c o main sol the installation path of the ST200 toolset must be defined this example assumes that the PATH environment variable has been updated with lt tools dir gt Finally if this example is to be used in real code it would be better to define the SwapBytes function as inline and provide it through an appropriate header file Understanding intrinsic models The inner workings of an intrinsic can be difficult t
23. aligned 8 short array 3 _ attribute aligned Applied to a type typedef int more aligned int _ attribute aligned 8 Ij STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 112 Attributes weak Applied to a function Causes the function to be emitted as a weak symbol Set to 0 if the symbol is not defined at link time This is primarily of use in defining library functions which can be overridden in user code void d_stub void _ attribute __ weak if d_stub d_stub Applied to data Causes the declaration to be emitted as a weak symbol rather than a global symbol This is primarily of use in defining variables which can be overridden in user code int debug _ attribute weak 0 alias Applies only to functions The required functionality is to provide an alias name for a given function Often used in conjunction with the weak requirement to define an alternate weak name for a given function void useful_func void Do something void useful void __attribute_ alias useful_func packed Applies only to data Specifies that a variable or structure should have the smallest possible alignment one byte for a variable and one bit for a field unless a larger value with the aligned attribute is specified The specified data alignment is applied during data layout and the code generator emits safe sequence of instructions
24. are used by the compiled simulator _ longjmp __setjmp _longjmp _setjmp call comment entry import return sversion type 11 2 9 8 Restrictions on standard directives A number of restrictions currently apply to standard directives The following directives are not currently permitted in the text section ascii asciz byte datal data2 short string The following directives are permitted in the bss section but they only have an impact on the size of the bss section not its content because the bss section has no content in the binary file ascii asciz byte datal data2 short string data4 data8 hword long octa quad real4 word single double float The following directives are currently ignored dc dc b dc d dc 1 dc s dc w dc x dcb dcb b dcb d dcd 1 dcb s dcb w dcb x ds ds b ds d ds 1 ds p ds s ds w ds x fill lflags mri org p2align p2alignw p2alignl gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 192 11 3 PRELIMINARY DATA Invoking the assembler Invoking the assembler 11 3 1 Assembler command line 11 3 1 1 hi Here is a a brief summary of how to invoke st200as st200as a hls file EB EL I dir J L mcore st220 st231 o objectfile R statistics v verbose version version w Z files The ass
25. bar goto array il foo return foo bar return bar hack return hack STMicroelectronics ADCS 7508723H that has type void For example amp amp hack 9j ST200 Micro Toolset User Manual 100 6 2 4 Note 6 2 5 6 2 6 hy PRELIMINARY DATA Extensions to the C language family Naming an expression s type A name can be given to the type of an expression using a typedef declaration with an initializer To define name as a type name for the type of expression do typedef name expression This can be used in conjunction with the statements within expressions feature described in Section 6 2 1 For example to define a safe maximum macro that operates on any arithmetic type define max a b typedef _ta a _tb b ta _a a _tb _b b a gt b a _b The reason for using names that start with underscores for the local variables is to avoid conflicts with variable names that occur within the expressions that are substituted for a and b In the future the GNU language may include a new form of declaration syntax that allows the declaration of variables whose scopes start only after their initializers this will be a more reliable way to prevent such conflicts Referring to a type with typeof typeof allows you to refer to an object data type by referring to an object of that type It is particularly useful to write generic and safe macro definition
26. calls options Instrumenting functions finstrument functions The finstrument functions option provides standard GCC functionality Using this option generates instrumentation calls for entry and exit to functions Just after function entry and just before function exit the following profiling functions will be called with the address of the current function and its call site void _ cyg profile func enter void this _fn void call_site void _ cyg profile func exit void this _fn void call_site e The first argument is the address of the start of the current function which may be looked up specifically in the symbol table e The second argument is the address of the call site from where the current function was invoked It corresponds to an address in the range of the caller function addresses that may be found in the symbol table of the executable The functions that are inlined by the compiler are not instrumented To force instrumentation of all functions use the fno inline option to disable inlining A function may be given the attribute no_instrument_function in which case this instrumentation is not done This can be used for example for the profiling functions listed above high priority interrupt routines and any functions from which the profiling functions cannot safely be called perhaps signal handlers ifthe profiling routines generate output or allocate memory The program must be linked with an obj
27. contains only an inner loop then outer loop unrolling followed by the loop fusion of the resulting inner loops is attempted This transformation known as unroll and jam is especially useful to create parallel execution opportunities when the innermost loop alone does not present such opportunities Unroll and jam example Ensure ad and sd do not alias pragma unroll 2 for i 0 i lt 16 i int sum 0 for k M k lt 8 M k sum sd k sd k i ad i sum gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 50 4 2 2 hi PRELIMINARY DATA Loop optimization pragmas becomes for i 0 i lt 16 i 2 int sum0 0 int suml 0 for k M k lt 8 M k sum0 sd k sd k i suml sd k sd k i 1 ad i sum0 ad i 1 suml The following tips provide information on how to control the desired inner loop unrolling with the pragma unroll value e A counted loop with a compile time constant trip count is always fully unrolled if a pragma unroll with a value greater or equal to the loop trip count is specified e When a counted loop is not fully unrolled the pragma unroll value is rounded to the greatest power of two lower than the specified unrolling value e The maximum size of a loop after unrolling is controlled by the command line option OPT unroll_size lt n gt pragma ivdep This pragma instructs the compiler to liberalize dependence analy
28. ext hash_set gt lt ext slist gt lt ext iterator gt Table 23 Supported extension headers oo 7 ADCS 7508723H STMicroelectronics ST200 Micro Toolset User Manual 42 PRELIMINARY DATA Standard Template Libraries STL support 3 7 3 Supported backward compatibility headers All the following backward compatibility headers are supported unless otherwise stated Using these files directly is not recommended the compiler warns about this usage as being deprecated To remove this warning use the Wno deprecated compiler option Header files lt algo h gt lt map h gt lt algobase h gt lt multimap h gt lt alloc h gt lt multiset h gt lt bvector h gt lt complex h gt lt defalloc h gt lt new h gt lt ostream h gt lt pair h gt lt deque h gt lt queue h gt lt fstream h gt lt rope h gt lt function h gt lt set h gt lt hash_map h gt lt hash_set h gt lt hashtable h gt lt slist h gt lt stack h gt lt stream h gt lt heap h gt lt streambuf h gt lt iomanip h gt lt strstream h gt lt iostream h gt lt tempbuf h gt lt istream h gt lt iterator h gt lt list h gt lt tree h gt lt vector h gt hy Table 24 Backward compatibility headers STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA RTTI notes 43 3 7 4 Identifyi
29. i lt proc gt Start symbol with its weight default is main 1 0 Several b options are allowed Weight is only taken into account in static mode Ignore symbol default is empty Several i options are allowed See Section 10 4 4 How to configure binopt on page 171 Algorithm specific options cacheline c lt nb gt chunksize s lt size gt fetch f lt size gt Number of lines in the cache default is 512 for all algorithms except for PH90 Chunk size default is 64 Each function is split into chunks of size lt size gt only for TRG and LTRG Size of addend to size in cache line to take into account prefetch default is 1 only for COL and PH_COL sizecacheline z lt size gt Size of a cache line in bytes default is 64 for all algorithms except for PH90 I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 170 binopt call graph specific options deffreg e Default call site freguency default 1 000000e 00 for non instrumented part of code only for static mode prune p lt float gt Percentage of the sum of edge weights kept for pruning graph default 100 1 000000e 07 only for static mode trace t lt file gt Branch sampling trace file syntax src dest nb of calls only for profile mode 10 4 3 binopt dump options binopt enables a call graph to be generated either a static call graph
30. implements variations of the GBSC97 algorithms This algorithm might take a very long time to execute gj STMicroelectronics ST200 Micro Toolset User Manual PRELIMINARY DATA 160 st200cc options deadcode no deadcode Activate deactivate dead data and dead code removal Dead code and data removal is done in several steps e In the assembly phase the assembler is instructed to emit all relocations e The link phase is split into several phases Apre link phase generates a relocatable image of the executable po file An optimization phase BINOPT removes unused symbols and generates a lightened relocatable image A final link phase maps the optimized relocatable file to an executable 10 2 1 Other options All the binopt binary options may be passed to st200cc by prefixing them with Wo see Section 10 4 binopt on page 166 10 2 2 Default behavior By default only moveable procedures in the text section are candidates to move Code in user defined sections are not taken into account by binopt however a layout file can be defined for these procedures with the icache mapping option to st200cc However since dead code and data removal is based on an analysis of the relocation graph of the whole application moveable symbols in any section are candidates for removal In addition binopt requires knowledge of the whole application so all symbols have to be defined in the relocatable entry obje
31. in standard C and ISO C99 the elements of an aggregate initializer for an automatic variable are not required to be constant expressions For example int foo int f int g int beat_freqs 2 f g f g return beat_freqs 0 beat_freqs 1 6 2 18 Compound literals Compound literals used to be called Constructor Expressions before ISO C99 normalized them under the term Compound Literals A compound literal looks like a cast containing an initializer include lt stdio h gt include lt malloc h gt struct foo int a char b 2 struct foo givefoo int x int y char a char b struct foo sfoo struct foo malloc sizeof struct foo Fill in the anonymous struct at once with a Compound Literal sfoo struct foo x y a b return sfoo GNU C allows initialization of objects with static storage duration by compound literals whereas ISO C99 does not 9j STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 108 Extensions to the C language family 6 2 19 Designated initializers This extension was called GNU Style Labeled Elements in Initializers It is now an ISO C99 feature It allows the initialization of particular elements of an aggregate a structure or an array by specifying the member name or the indices of the elements to initialize in any order const int widths f 0 9 1 10 99 2 100 3 int a
32. interface supported from a terminal shell The facilities provided by the st200gdb debugger are introduced in the Getting Started chapter of the ST200 Cross Development Manual STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H 1971 st200cc 2 1 2 1 1 PRELIMINARY DATA Getting started The st200cc compiler is similar to any command line compiler It is either invoked from a command line interpreter or from a Makefile and implicitly recognizes files by their extension Invoking the compiler The C compiler is invoked using the st200cc command st200cc lt argument gt where lt argument gt lt option gt lt input_file gt Examples st200cc S file c produces file s st200cc c file c produces file o Conflicting options are resolved by using the last option on the command line Any string that is not recognized as an option or a recognized input file is passed down to the link phase 9j STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 10 Getting started 2 1 2 Input and output File extension naming conventions are summarized in Table 1 and Table 2 Extension Convention C C language source file to be pre processed and compiled h C language header file Aa C language source file already pre processed s Assembly language source file to be assembled S Assembly language source file to be pre processed and assembled
33. is invoked just after a call instrumenting a function exit Function calls that are inlined by the compiler are not instrumented To force instrumentation of all functions use the fno inline option to disable inlining A function may be given the attribute no_instrument_function in which case this instrumentation is not done if the caller or the callee function has the attribute no_instrument_function The program must be linked with an object file that implements the function above to link correctly STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Profiling feedback optimization PFO 83 5 8 5 8 1 5 8 2 The main differences with the finstrument functions option are this instrumentation tracks caller callee address pairs instead of call site callee address pairs If the call site information is required use the finstrument functions option this instumentation provides the caller and callee name when available which avoids a specific post processing pass to retrieve the function names this instrumentation is at the call site and not in the callee thus for instance calls to top level library functions which are not instrumented are seen while finstrument functions do not see them to disable the instrumentation of the call to a particular library routine you must declare it with the no instrument function attribute this instrumentation is not standard GCC functional
34. mandatory to keep them in order The effect of this pragma is that the scheduler will serialize all load prefetch operations or respectively all stores in the loop Thus the memory read or write accesses as written in the C code are kept in order as long as no aggressive transformation occurs in the loop A scenario is when the user wants to keep memory writes in order to take advantage of a combining write buffer pragma loopseq WRITE for i 0 i lt n i a i a li 1 a it2 a it4 The pragma hints that the compiler should keep writes to the array in order If the loop is unrolled generating a large number of stores this improves locality and may take advantage of combining write buffers By default the compiler does not put restrictions on the ordering of non overlapping store operations A second scenario is when the user has scheduled by hand prefetch and load operations and wants to ensure that the compiler does not reorder them 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Loop optimization pragmas 57 4 2 8 pragma loopseg READ for i 0 i lt n i S ali __builtin_prefetch amp a i S The pragma hints that the compiler should keep the load and prefetch in order In this example the prefetch is not placed before it is effectively used in the next iteration by the load Heuristic pragmas pragma frequency_h
35. may inline and must inline functions May inline functions are selected by the compiler according to the following conditions e function is declared with the inline C keyword e the functions not declared inline are may inline candidates only if the INLINE only_inline off option is specified In this case the following categories are also may inline candidates function is declared with the static C keyword whose name is not weak and whose address is neither passed nor saved finally if the generated code does not follow the GP relative model the non weak condition is sufficient This large span condition is included to add inlining opportunities in the current programming model ofthe ST200 where there is currently no support for shared objects As a result no function is preemptible except by using the weak attribute Must inline functions are specified by the user through the command line option INLINE must fn1 fn2 May inline and must inline functions are then checked against several criteria to decide whether to inline them or not Inlining criteria Each candidate function is checked against inlining exclusion cases which include e requires no inlining by the user INLINE never fn INLINE none command line options e recursive function e vararg function e exception handler After this preliminary test each candidate function is inlined regardless of cost if it is marked must inline or if the I
36. no abi Warn when compiler generates code that is probably not compatible with the vendor neutral C ABI The default is wabi W no ctor dtor privacy Warn when a class seems unusable because all the constructors or destructors in that class are private The default is Wctor dtor privacy W no Jeffc Warn about violations of style guidelines from Scott Meyer s Effective C book The default is Wno effc W no old style cast Warn if an old style cast to a non void type is used within a C program The default is Wno old style cast Table 18 C warning options I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 34 Option W no overloaded virtual C specific command line options Description Warn when a function declaration hides virtual functions from a base class The default is Wno overloaded virtual W no deprecated Do not warn about usage of deprecated features The default is wdeprecated W no pmf conversions Disable the diagnostic for converting a bound pointer to a member function to a plain pointer The default is wpmf conversions W no reorder Warn when the order of member initializers given in the code does not match the order in which they must be executed The default is Wno reorder Table 18 C warning options The options in Table 18 take a positive form a negative form can be syst
37. noinline next directive All calls to 1 are candidates for inlining except the one directly following pragma noinline next int ig 0 inline void f1 int i ig i void main 1 1 1 is candidate for inlining pragma noinline next f1 1 2 1 is not marked for inlining 1 3 1 is candidate for inlining printf result is d n ig Example 2 This example illustrates the use of the pragma inline_function directive All calls to 1 following the pragma inline function f1 directive are forced to be inlined except the one directly following pragma noinline_next f1 The call to 2 following the pragma inline next 2 is also forced to be inlined while the first call to 2 is only a candidate for inlining inlining depends on the respective weights of 2 and its caller int ig 0 int jg 0 inline void f1 int i ig i inline void 2 int i jg i void main pragma inline_function f1 1 1 1 is forced to be inlined 2 1 2 is candidate to inlining pragma noinline next f1 1 2 1 is not marked for inlining pragma inline_next 2 2 3 2 is forced to be inlined 1 3 1 is forced to be inlined printf result is d d n ig jg 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Inlining 67 Example 3 This example illustrates the use of the pragma defaultinline
38. not make assumptions that may be false specifically check restrict annotations and optimization pragmas check that the code does not exercise language edges or does not violate language standards an example of undefined behavior is to assume a specific behavior of shift operators when the shift amount is negative or bigger than the size of the type shifted 9 4 Work around The following can be carried out to temporarily work around a compiler bug hi Demote the optimization level to 01 or 00 when compiling the specific file creating the problem either in category 1 or 2 See Section 9 2 1 and Section 9 2 2 Remove the optimization pragmas or restrict annotations Finally check that you have an up to date compiler release STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Reporting a compiler bug 149 9 5 Reporting a compiler bug Carry out the following if a compiler bug is encountered e Obtain your compiler version by running the command st200cc version e Ifthe compiler bug is in category 1 see Section 9 2 1 on page 147 prepare a pre processed input file that can reproduce the problem e Ifthe compiler bug is in category 2 see Section 9 2 2 on page 148 prepare a source set and Makefile that can reproduce the problem e Supply the full command line that generates the problem e Report the result of the following command in the shell that you use uname a e Prepare a de
39. of Red Hat Software Inc Linux is a registered trademark of Linus Torvalds 2002 2003 2004 2005 STMicroelectronics All Rights Reserved STMicroelectronics Group of Companies Australia Belgium Brazil Canada China Czech Republic Finland France Germany Hong Kong India Israel Italy Japan Malaysia Malta Morocco Singapore Spain Sweden Switzerland United Kingdom United States http www st com 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H 1971 PRELIMINARY DATA Contents Preface ST200 document identification and control ST200 documentation suite Conventions used in this guide 1 ST200 development system 1 1 ST200 compiler overview 12 ST200 C compiler 1 3 Toolset overview 1 4 ST200 Micro Toolset interface 1 4 1 Example command lines 2 st200cc 2 1 Getting started 2 1 1 Invoking the compiler 2 1 2 Input and output 2 2 Command line options ADCS 7508723H 2 2 1 Getting help 2 2 2 Overall options 2 2 3 C preprocessor options STMicroelectronics 9 10 11 11 11 12 Ij ST200 Micro Toolset User Manual 7 PRELIMINARY DATA 2 2 4 C dialect options 2 2 5 Warning options 2 2 6 Debugging options 2 2 7 Profiling options 2 2 8 Call Trace instrumentation options 2 2 9 Optimization options 2 2 10 Code generation options 2 2 11 OPT options 2 2 12 Data prefetching options 2 2 13 Inlining options 2 2 14 Interprocedural
40. on o exe o Profile st200run d st200sim 220 MODE ISS TRACING_ON true TRACE PLUGIN MODULE lt tools dir gt host tplugins TracePlugin OUTPUT_TRACE FILE trace dt exe Re link exe must still exit st200cc icache opt on icache profile trace dt icache profile exe exe o opt_exe o Wo v v STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Examples 165 10 3 5 Using profile driven ICache optimizations using O2 or higher The compiler optimization options 02 or higher are used Build first executable with instruction cache information default behavior with 02 or upper st200cc c 02 c st200cc o 02 o exe no deadcode Profile st200run d st200sim 220 MODE ISS TRACING ON true TRACE PLUGIN MODULE lt tools dir gt host tplugins TracePlugin OUTPUT_TRACE FILE trace dt exe Re link with the profile file st200cc o 02 icache profile trace dt icache profile exe exe o opt_exe Wo v v 10 3 6 Compiling with st200gprof file driven ICache optimizations Compile using profiling st200cc c 02 keep o exe pg no deadcode Execute and create the gmon out 000 file st200run d st200sim 220 MODE ISS exe Recompile source file without profiling st200cc c 02 icache profile gmon out 000 icache profile exe exe keep o opt_exe Wo v v Lia STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 166 binopt 10 3 7
41. output_extension gt and can be renamed using the o option Option Description c Compile or assemble the source file but do not link s Stop after the compilation phase E Stop after the preprocessing phase Output is send to stdout v Print on stderr the commands executed to run the compilation phases The message generated indicates the release identity version Display the version numbers of the invoked compiler and stop dumpversion Print the compiler front end version for example 2 95 2 and stop keep Keep intermediary files produced by the compilation phases Table 3 Overall options gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 12 Command line options 2 2 3 C preprocessor options The preprocessor is run on each C source file before actual compilation The options in Table 4 control how the sources are pre processed Option Description E Only the preprocessor is run C The preprocessor does not discard comments Use with the E option P The preprocessor does discard line information Use with the E option Ddef Define the macro definition with the string 1 as the definition Ddef defn Define the macro definition as defn M Generates a list of object file dependencies suitable for a Makefile MM Similar to M but ignores system header files that is header files included by lt header h gt MG Alo
42. sizeof tt din sizeof tt printf sizeof buffer d n sizeof buffer char data 10 10 int main int argc char argv sadcat Foo Bar tester 4 data tester 10 data return 0 9j STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 104 PRELIMINARY DATA Extensions to the C language family 6 2 13 Macro with variable number of arguments Note hy This extension enables a macro to be defined that can safely be expanded into a function with a variable number of arguments These macros are also called CPP vararg macros For example the following C program define eprintf format args fprintf stderr format args eprintf success n eprintf s d input file name line number gets expanded into fprintf amp _iob 2 success n fprintf amp iob 2 s d input file name line number GNU C supports two types of variable number of arguments syntax The ISO C99 format which uses VA ARGS and the GNU format that uses args The ISO C99 format does not support the case where the number of parameters passed as part of the ellipsis is zero GNU C reuses the trick to absorb the comma in this case For example include lt stdio h gt define gnu_eprintf format args fprintf stdout gnu_eprintf format args define isoc99 eprintf format fprintf stdout isoc99 eprintf format __ VA ARGS de
43. subtract 135 libboard a 22 switching model and ST220 names 131 lib 22 A a ibcore a viterbi 141 inttypes h 28 DEA 194 ipa 86 libsoc a 22 IPA aggr_eprop 87 link register 184 185 IPA cgi 87 linker See st200ld IPA cprop 87 Linu 3 za IPA depth 87 load application See st200run IPA dfe 87 long long 101 IPA dve 87 lvalues 100 106 IPA forcedepth 87 M IPA inline 87 IPA keeplight 87 Ta IPA maxdepth 88 m no auto prefetch 76 macro IPA multi_clone 88 definition 100 IPA node_bloat 88 variable number of arguments 104 I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 202 main 113 malloc 39 114 math h 28 mboard 22 mcore 22 25 190 193 MG 12 minstrument calls 16 81 83 MM 12 mode 115 mruntime 21 msoc 22 mtost220 h 131 mvisibility decl 89 95 N new 44 newline 179 embedded 105 no instrument function 81 82 no gcc 24 36 noinline 61 noreturn 39 97 114 nostdinc 23 nostdinc 36 nostdlib 23 O O 16 26 o 11 00 16 148 01 16 148 02 16 152 161 03 16 OPT 26 Olimit 62 alias 69 cray_ivdep 50 57 PRELIMINARY DATA liberal_ivdep 50 unroll_size 50 optimization aliasing 71 75 asm 122 call trace instrumentation 81 83 data prefetching 75 80 GNU attributes 114 icache and dead code 151 icacheopt options 167 172 inlining 59 69 interprocedural analysis 86 profiling feedback 83 85 st200cc ICache options 156 159 st200cc options
44. that are read appear to the right When more than one operand is read written the operands are separated by There are a small number of operations branch and prefetch operations that do not write an operand and hence have no The optional prefix c0 denotes cluster 0 Example c0 slct r11 sub r2 b2 r3 3 3 r4 11 2 8 2 Conditional branches Conditional branch operations read a branch register b0 y and conditionally branch to a destination Example c0 br b0 1 dest label In this example the branch is taken when b0 1 contains 1 Branch registers which are read by conditional branch operations are written by other operations including compares and arithmetic operations that generate a carry These branch registers are also read by select operations and arithmetic operations that read a carry bit 11 2 8 3 Call goto and return call and goto operations are similar to branches except that they are unconditional Each of these operations has two forms an immediate PC relative form and an indirect form that uses the system link register r63 Furthermore the call operations write the link register with the address of the bundle following the current bundle The return operation is a pseudo operation for the indirect form of the goto In order to make all the state used by an operation explicit these operations explicitly name the link register even when it is implicit gj STMicroe
45. the context of position independent code generation f pic where symbol visibility has a significant impact on code performance and the dynamic symbol table size Two options are provided e fvisibility default protected hidden internal this option specifies the default visibility to apply to symbols defined in the current source file This does not set the visibility of symbols declared externally e mvisibility decl lt file gt this option specifies a visibility specification file that the compiler can use to determine the visibility for a symbol declaration or defintion These options are useful to optimize a shared object DSO or a relocatable library as defined by the ST200 relocatable library model described in the ST200 Cross Development Manual 5 10 1 Introduction In the context of fpic code generation symbol visibility has a significant impact on code generation In addition to GP relative addressing which is an invariant of PIC code some other code generation overheads appear depending on the symbol visibility I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 90 57 ST200 Micro Toolset User Manual PRELIMINARY DATA Symbol visibility specification These overheads are summarized in Table 30 Overhead Default Protected Hidden Internal visibility visibility visibility visibility The GP value must be set up on entry to the function symbol as the function can be cal
46. the estimated static call graph with an external icg file This is only for optimizations based on a static analysis To do this use Wo icg myconfig icg A icg file is a list of the following items source destination frequency Where frequency is a float and source and destination are function names A icg file can be useful to enrich the estimated call graph with syscalls that are not detected via a simple relocation analysis A default icg file is taken Use the following command to obtain the default file Wo icgdump See Section 10 4 4 How to configure binopt on page 171 for more details The following option preserves a symbol and all its descendants during the dead code phase More than one preserved option may be given Only one name may be given with each preserved option This symbol can be a function or data STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Examples 163 Wo preserved my symbol The following option preserves all symbols defined in my_ section and in all its descendants More than one section preserved option may be given Only one name may be given with each section preserved option Wo section preserved my section Likewise the Yo path options can be used to define a specific path for the BINOPT phase 10 3 Examples 10 3 1 Compiling with static ICache optimizations st200cc 02 o opt_exe c or st200cc icache opt on i
47. the statement The key symbol determines the syntax of the rest of the statement Assembler directives begin with a The directives accepted by the assembler are described in Section 11 2 9 Assembler directives on page 187 Any statement that begins with a letter is part of an ST200 instruction bundle The bundle terminator is also a statement A statement is terminated by a newline character Newlines within character constants are an exception they do not terminate a statement It is an error to end any statement with end of file the last character of any input file must be a newline Statements may be written on multiple lines provided that each line other than the last ends with a backslash 1 11 2 3 5 Labels A label is a symbol immediately followed by one or two colons or Whitespace before a label or after the colon s is permitted but whitespace between the symbol and colon s of a label is not permitted Labels followed by a single colon are treated as local symbols labels followed by a double colon are global symbols they are visible to other object modules linked with the output of the assembler Symbols can also be marked as global with the global directive 11 2 4 Symbols 11 2 4 1 The lexical specification for symbols has already been described This section defines the semantics of symbols Giving symbols other values A symbol can be given an arbitrary value by writing a symbol follo
48. to avoid causing a misalign trap struct foo char a int x _ attribute _ packed 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Attributes 113 Note used The GCC manual specifies that the used attribute may only apply to functions For st200cc it may also apply to variables e The used attribute attached to a function means that the code must be emitted for this function even if this function appears never to be referenced e This attribute attached to a variable means that the definition must be emitted for the variable even ifit appears that the variable is not referenced The used attribute follows the same syntax as any GCC attribute For a procedure static int Foo _ attribute__ used For uninitialized data static foo _ attribute _ used For initialized data static foo _ attribute used 2 The assembly has been specifically extended to support this attribute type Foo function used type foo object used A motivation for using this attribute is to avoid the deletion of an unreferenced symbol by the dead code dead data or IPA optimization This can be useful for debugging purposes for instance a function dumping a specific data structure that is called only interactively from debugging sessions is removed if not marked used since the compiler does not find any reference to it constructor and destructor Applies onl
49. which is really a header for a variable length object include lt stdio h gt include lt stdlib h gt struct line int length char contents 0 Y struct line newline unsigned int this length struct line thisline struct line malloc sizeof struct line this length thisline gt length this_length return thisline void delline struct line thisline free thisline int main int argc char argv enum _ MAXL 128 enum _L 16 struct line lines __MAXL int i printf sizeof line d n sizeof struct line for i 0 i lt _ MAXL i lines i newline __L for i 0 i lt MAXL i delline lines i puts Done return 0 57 STMicroelectronics ST200 Micro Toolset User Manual r ADCS 7508723H PRELIMINARY DATA Extensions to the C language family 103 6 2 12 Array of variable length An array of variable length is an automatic array defined with a length that is not a constant expression Also known as a VLA include lt stdio h gt include lt stdlib h gt void sadcat char s1 char s2 char str strlen s1 strlen s2 1 strcpy str s1 strcat str s2 printf s s s n sl s2 str printf sizeof str din sizeof str void tester int len char buffer len len int i 0 j 0 char tt len len for i 0 i lt len i for j 0 j lt len j buffer i j i j printf
50. with their model names and properties The tables contain e the model name of the intrinsic e the purpose of the intrinsic C operator supports C arithmetic C runtime arithmetic helper supports optimized C arithmetic DSP operator saturating fractional arithmetic ETSVITU operator standard conformance operator e the ST200 specific name The intrinsic functions are generally categorized by operator Within each category they are grouped by operand and result type All the compiler generated arithmetic intrinsics are held in the library libgec a STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Intrinsic functions summary 135 8 5 1 Functions ints2_edde_intsa_int32 TT eaaw int16_addc_int16_int16 ETSI add __addch Table 33 Add intrinsics int16_subc_int16_int16 ETSI sub __subch Table 34 Subtract intrinsics C int32 mege int32 ETSII negale negou __int16_negc_int16 ETSI negate __negch Table 35 Negate intrinsics Intrinsic Purpose ST200 name int32 min int32_int32 C optimization __minw int16_min_int16_int16 C optimization __ minh uint32 min uint32_uint32 C optimization __minuw __uint16_min uint16_uint16 C optimization minuh Table 36 Minimum intrinsics gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA
51. 0 PH_COL An algorithm inspired from PH90 for graph merge and COL for graph node union take into account colors to minimize conflict insert blank when needed TRG Procedure Placement Using Temporal Ordering Information Gloy Blackwell Smith Calder 1997 published in the Proceedings of Micro 30 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H y Y PRELIMINARY DATA Assembler 11 1 Introduction This chapter documents the assembler and the assembly language for the ST200 processor family The ST200 assembler is based upon gas the GNU assembler Much of the information about assembler directives and expression syntax is repeated in abbreviated form from the standard gas documentation The primary areas in which the ST200 assembler deviates from gas are in the syntax for instructions and in the restrictions placed upon the standard directives In addition the ST200 assembler accepts a number of ST200 specific directives and options The description of ST200 instruction syntax assumes some familiarity with the architecture of the ST200 processor family Section 11 2 details the syntax of assembler source programs Section 11 3 describes how the assembler is run the command line options input and output file formats I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 176 Assembler syntax 11 2 Assembler syntax 11 2 1 General description
52. 0 50 2 means that the LNO prefetch_ahead option expects an integer argument whose range is in the 0 50 interval for which the default value is 2 Alternatively it is possible to specify the number of loop iterations to prefetch ahead using the command line option LNO prefetch_iters ahead n which makes the compiler prefetch array references for the loop n iterations after the current iteration LNO prefetch_iters_ahead 0 50 2 Caution The compiler may also automatically unroll the loop the value of n specifies the number of loop iterations before this automatic unrolling Automatic prefetching is not performed upon arrays that have the built in function __builtin_prefetch applied to them For example the option LNO prefetch iters_ ahead 0 50 2 gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 80 5 6 hy PRELIMINARY DATA Profiling controls how many iterations an automatic prefetch instruction must be issued ahead of its associated memory reference This value is used only if the step of the memory access in an iteration of the loop is greater or equal to the size of a data cache line The option LNO clean_miss_penalty 0 1000000000 140 controls the number of cycles between the issue of a prefetch instruction and the availability of the data in the prefetch buffer The option LNO dcache_prefetch_buffers 0 1000 8 controls the number of prefetch buffers available on
53. 0 by including include lt mtost220 h gt This has the effect of renaming all models to ST200 intrinsics names An application written exclusively using the ST200 names can easily be switched to using model names by including include lt st220tom h gt This has the effect of renaming all ST200 intrinsic names to model names To allow the remapping ofnames use one set of names exclusively that is use either the model names or the ST200 intrinsic names _ ____ iy STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 132 hy PRELIMINARY DATA Using intrinsics from C C Example The following example demonstrates the usage of ST200 intrinsics in the application source code while maintaining the ability to compile on a generic target by switching automatically back to models if defined __st200__ Include intrinsics definitions when target is ST200 include lt st220 h gt else st200__ Include models and renaming scheme when target is unknown include lt imodels h gt include lt st220tom h gt endif st200 unsigned int SwapBytes unsigned int x On ST200 this will be emitted as a single instruction bswap Sr16 Sr16 On other targets thanks to lt st220tom h gt macros this name will be replaced by the generic name and looked up in the models source files Thus the generated code will be a call to t uint32 swapb uint32
54. 00cc filel o file2 o lmylib then the files will be processed in the order filel o file2 o libmylib a However if the following is specified st200cc filel o lmylib file2 o then the files will be processed in the order filel o libmylib a file2 o In this case ile2 o should not refer to any symbols defined in libmylib a Ldirectory Add directory to the beginning of the search list for library files nostdlib No predefined libraries search path Table 13 Directory options The search path for the various phases of the compiler can be overridden by using the option Y lt phase gt lt path gt where lt phase gt can take the values listed in Table 11 and lt path gt is the path of the required tool There must be a comma and no spaces separating Y lt phase gt and lt path gt ADCS 7508723H I STMicroelectronics ST200 Micro Toolset User Manual 24 2 2 21 Environment variables PRELIMINARY DATA Predefined macros Currently there are no special environment variables that affect st200cc 2 3 Predefined macros Predefined macros are described in Table 14 Note 1 The list of macros currently defined can be obtained by typing st200cc E dM filename c where filename c can be any c file including an empty file 2 Do not rely on a macro that is not documented even if it is currently defined 3 Some macros values are subject to change along with compiler evolutions for instance front en
55. 116 __PRETTY_FUNCTION_ 110 _ restrict 13 __restrict__ 13 __ST200 25 _ST200_ 25 _ st200_ 25 _ ST200CC_ 24 _ ST200CC_DATE_ 25 _ ST200CC_MINOR__ 24 __ST200CC_PATCHLEVEL_ 24 __ ST200CC_VERSION _ 25 _ st200mul32 145 __st200mul64h 145 __st200mul64hu 145 __st200mulfrac 145 __ST220_ 25 __st220_ 25 131 __ST231_ 25 _ st231_ 25 _ STDC_HOSTED_ 26 _ STDC VERSION 26 _ STRICT_ANSI_ 25 37 _ VA ARGS 104 _ word__ 116 _GLIBCPP_VERSION 43 57 _GLIBCXX_VERSION 43 _LANGUAGE_ASSEMBLY 25 _LANGUAGE_C 25 _LANGUAGE_C_PLUS_PLUS 37 _Wmultichar 14 A a elf 6 8 ABI 190 abort 114 addcg 122 aggregate initializing 108 alias 38 111 112 aliasing 71 75 align 38 110 aligned attribute 111 112 alignof 38 ANSI 2 13 ansi 13 109 array initializing 108 variable length 103 zero length 102 asm See GNU ASM assembler See st200as assembly language 1 B Backus Naur Form xv bare machine 7 21 binopt 21 151 166 BNF See Backus naur Form board x 22 bootboard o 22 bootcore o 22 bootsoc o 22 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Bsymbolic 91 bugs 147 149 C C 12 C3 c 11 C 3 107 109 C See also st200c C89 2 13 14 C99 2 13 27 29 97 101 104 108 restrict keyword 13 clobber list 119 codereorder passing options to 21 comment assembler 176 section 58 compiler See st200cc complex h 27 constant assembler 177 constructor 38
56. 165 intrinsics 131 passing options to 21 relocatable file 161 162 selecting libraries 23 st200run 4 7 165 ST220 1 2 st220 h 130 st220tom h 131 st220types h 126 ST231 2 standard template libraries See st200c statement assembler 179 static function 61 keyword 60 std 13 25 27 37 std c 98 33 std gnu 98 33 stdbool h 29 stdint h 28 stdio h 28 29 I STMicroelectronics ST200 Micro Toolset User Manual 204 strfmon 115 strftime 115 structure initializing 108 SunOS 3 symbol assembler 177 visibility 89 95 T target 6 8 tgmath h 27 throw 44 TracePlugin 154 155 traditional 109 typedef 109 typeid 43 typeinfo 43 typeof 38 100 U unary operator 99 106 union 109 used 113 V v 11 vararg 60 104 version 11 visibility attributes 114 VLA 103 void 99 106 volatile 121 W w 13 hi ST200 Micro Toolset User Manual PRELIMINARY DATA W lt phase gt lt arg gt 21 W no labi 33 W no ctor dtor privacy 33 W no deprecated 34 WI no Jeffc 33 WI no Jold style cast 33 W noloverloaded virtual 34 W no pmf conversions 34 W no reorder 34 Waggregate return 15 Wall 13 148 Wbad function cast 14 Wcast align 15 Wcast qual 15 wchar h 28 Wchar subscripts 14 Wconversion 15 weak 38 60 111 112 pragma 58 Werror 13 Werror implicit function declaration 14 Wformat 14 whitespace 176 177 179 Wimplicit 14 Wimplicit function declaration 14 W
57. 2 4 6 PRELIMINARY DATA 65 If pragmas are provided at an invalid scope that is outside of a function the following message is displayed warning pragma noinline function foo ignored incorrect scope To help track misspelling a warning is also displayed if a pragma could not be applied to any function call pragma noinline next bar foo i leads to warning pragma noinline next bar matched no call noinline and always_ inline attributes In order to enable the user to inhibit inlining of one function wherever it is called the noinline attribute is introduced and is used at the function declaration level Conversely to enable the user to force inlining of one function wherever it is called the always inline attribute is introduced Precedence Command line options INLINE must foo and INLINE never foo take precedence over both pragmas and attributes Attributes take precedence over pragmas That is a function declared with __attribute _ noinline is never inlined regardless of pragma inline_xxx statements However the user can override this behavior with the INLINE must foo command line option If several contradictory pragmas with same scope apply to the same function the last one overrides the other ones 9j STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 66 Inlining 5 2 4 7 Examples Example 1 This example illustrates the use of the pragma
58. 23456789abcdefABCDEF Bignums A bignum has the same syntax and semantics as an integer except that the number or its negative may require more than 32 bits Bignums are not necessarily permitted in all places where integers are permitted Floats The ST200 floating point runtime model defines two of the IEEE 754 standard data type formats single and double The IEEE single format has a precision of 24 bits 24 significant bits and 32 bits overall The IEEE double format has a precision of 53 bits and 64 bits overall float lt expression gt double lt expression gt Where lt expression gt should have the format 0e lt hex digits gt The lt hex digits gt are the hexadecimal form of the IEEE representation 32 bit for float 64 bit for double It is not possible to use true floating point format for example 1 0e 10 because this is not currently implemented in the assembler real4 lt expression gt lt number gt real8 lt expression gt lt number gt Where lt expression gt is an integer or hexadecimal constant just like data4 or data8 The integer or hexadecimal constant is the binary representation of the IEEE format 32 bit for real4 64 bit for real8 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Assembler syntax 179 11 2 3 4 Statements A statement begins with zero or more labels optionally followed by a key symbol which determines the type of
59. 23H PRELIMINARY DATA xi 11 3 1 Assembler command line 192 11 3 2 Error and warning messages 194 Revision history 195 Index 197 ky STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA xii 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H y Y PRELIMINARY DATA Preface This document is part of the ST200 documentation suite detailed below Comments on this or other manuals in the ST200 documentation suite should be made by contacting your local STMicroelectronics Limited sales office or distributor ST200 document identification and control Each book in the ST200 documentation suite carries a unique ADCS identifier in the form ADCS nnnnnnnx Where nnnnnnn is the document number and x is the revision Whenever making comments on a ST200 document the complete identification ADCS nnnnnnnx should be quoted ST200 documentation suite The ST200 documentation suite comprises the following volumes ST200 Micro Toolset User Manual ADCS 7508723 This manual describes the software provided as part of the ST200 tools It supports the development of ST200 applications for embedded systems Applications may be developed in either a stand alone environment or under the OS21 real time operating system This manual also contains reference material relating to the ST200 Micro Toolset I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual Xiv 57
60. 32 C operator __mulw __uint32_ mul_uint32_uint32 C operator _ muluw int32 div int32 int32 C operator __divw __uint32_div_uint32_uint32 C operator divuw int32_mod_int32_int32 C operator __modw uint32_mod_uint32_uint32 C operator __moduw Table 51 Integer 32 bit support Intrinsic Purpose ST200 name int64_add_int64_int64 C operator __addl uint64_add_uint64_uint64 C operator __addul int64_sub_int64_int64 C operator _ subl uint64_sub_uint64_uint64 C operator subul __int64_neg int64 C operator __negl __uint64_neg uint64 C operator __negul int64 shr int64 uint16 C operator __ shri uint64_shr_uint64_uint16 C operator __shrul int64 shi int64_ uint16 C operator __ shill __uint64_shl_uint64_uint16 C operator __shlul int64_mul_int64_int64 C operator _ mull __uint64_mul_uint64_uint64 C operator __mulul int64 div int64 int64 C operator _ divl uint64 div uint64 uint64 C operator divul int64 mod int64 int64 C operator __modl uint64_mod_uint64_uint64 C operator __modul Table 52 Long long support 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Intrinsic functions summary 143 Intrinsic Purpose ST200 name int64 addc int64 int64 DSP operator __addcl ID add int64 subc int64 int64 DSP operator subel ID sub _ int64 negc int64 DSP operator __negcl D_neg __int64_absc_int64 DSP operator __abscl D_abs int64 max int64_
61. A 126 Naming intrinsics Types Table 31 summarizes the type names use in the intrinsics description Description Name Models mapping ST200 mapping size ST200 notation int16 short short 16 h uint16 unsigned short unsigned short 16 uh Fractional g15 fract16 short short 16 h equivalent to signed short int32 int int 32 w uint32 unsigned int unsigned int 32 uw Fractional q31 fract32 int int 32 w equivalent to signed int Fractional q63 fract64 long long long long 64 1 int64 long long long long 64 1 uint64 unsigned long long unsigned long long 64 ul Table 31 ST220 intrinsic type names Note 1 These types are defined in the st220types h files which is part of the compiler distribution This file applies to both the ST220 and ST231 2 Operations on fractions are specifically denoted by the operator name with the addition of the suffix to the standard name 3 Using models requires a full 64 bit implementation of the long longand unsigned long long types The model requires the standard C99 long long type The standard PC compiler uses __ int 64 to support a full 64 bit type Other compilers can be obtained that do support the long long type for example a gcc based compiler Refer to http sources redhat com cygwin 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H Naming intrinsics Operations PRELIMINARY DATA 127 Table 32
62. An ST200 assembly file consists of three types of fields comments directives and instructions Comments are treated by the assembler as white space and other than syntax have little bearing on the subsequent description Directives include constant declarations memory allocation commands and commands to guide both the assembler and linker Instructions in the ST200 architecture may consist of multiple operations that are to be executed simultaneously In the following discussion we use the term bundle to refer to a group of operations that are defined to be executed simultaneously An assembly file may consist of an arbitrary interleaving of directives comments and bundles with a few restrictions on specific directives A bundle consists of a sequence of operations and comments terminated by a pair of semicolons on a separate line 11 2 2 Comments There are two types of comments supported by the assembler In both cases the comment is equivalent to one space The input routines for the assembler filter out all comments and replace them with a single space e C style comments consist of an text beginning and ending with the next C style comments may not be nested e Line comments consist of any text on a single line beginning with the first pound character A line comment can appear on a line by itself or as the last thing on any input line To be compatible with past assemblers a special interpretation is g
63. Disable signed overflow warning Do not warn about signed overflow Include local labels Labels beginning with L upper case only or _ are called local labels Normally these labels are not represented by symbols in the object file This option instructs the assembler to create symbols representing local labels in the object file mcore st220 st231 o objectfile R statistics v verbose W Z ADCS 7508723H Specifies whether the assembler should select the ST220 or the ST231 encoding table The default if no command line option is found is ST220 It also encodes the corresponding information in the elf flags of the object file unless a assume st2xx directive is found in which case the elf flags will be the ones specified by the assume st2xx directive Name the object file The default output file created by st200as is a out The output file name can be used with this option Join text and data sections Instructs st200as to merge the data section with the text section in the object file Display assembly statistics Use statistics to display statistics about the resources used by st200as such as the total ezecution time taken for assembly in CPU seconds Announce version To determine which version of st200as is executed include the option v on the command line Suppress warnings By default all warnings are printed to the standard error file This op
64. IMINARY DATA Pragmas 4 1 Pragmas short description and syntax Optimization Syntax Scope Description y P P level pragma unroll Start of a loop body Unroll the loop 02 unroll amount unroll_amount times pragma ivdep Start of a loop body Liberalizes dependence 03 analysis pragma loopdep Start of a loop body Liberalizes dependence 03 PARALLEL VECTOR LIBERAL analysis pragma loopmod q r Start of a loop body Provides trip count 02 modularity information pragma looptrip n Start of a loop body Provide trip count 02 estimation information pragma pipeline p r Start of a loop body Controls pipeliner 03 pragma loopseq READ Start of a loop body Ordering of the READ 02 WRITE or WRITE accesses pragma frequency hint Applies to the function Execution frequency hint Any NEVER FREQUENT or statement that follows the pragma Table 25 st200cc pragmas I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 48 pragma ident string PRELIMINARY DATA Pragmas short description and syntax mawa Optimization Description E level Adds a comment Any section to an assembly file pragma weak symbol Marks a symbol as weak Any pragma inline_next function Function call site Inlining 01 pragma noinline_next function Function call site pragma inline_function function Function pragma noinlin
65. LF and the debug format is DWARF 2 The ST200 Micro Toolset supports both little endian and big endian code generation for ST200 targets Where applicable the available options are accessible through a command line interface similar to the UNIX style This will be familiar to most gec and cc users The toolset is installed in a directory structure which also follows the UNIX structure that is bin and 1ib This is described in more detail in Section 1 4 ST200 Micro Toolset interface on page 5 The compiler supports the ANSI C89 standard and partially supports the ANSI C99 standard see Section 2 4 C99 support on page 27 ST200 C compiler A GNU C compiler is provided which is documented in Chapter 3 st200c on page 31 Command line options which are common to both st200cc and st200c are documented in Chapter 2 st200cc on page 9 so C users should read both chapters STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Toolset overview 3 1 3 Toolset overview The ST200 Micro Toolset is a set of tools that allow C and C programs compiled for an ST200 target to be simulated on a host workstation or ezecuted on an ST200 target Supported platforms are e Solaris 2 5 8 e RedHat Linux 7 2 e RedHat Enterprise Linux 3 0 e Windows XP with any Cygwin environment from version 1 5 11 or higher e Windows 2000 with any Cygwin environment from version 1 5 11 or higher The ST200 Micro
66. Linker options The majority of arguments intended for linker phase such as W1 option are passed to the first relocatable link phase when this phase is needed However some specific options are only passed to the final link phase after BINOPT phase T W1 T W1 r r W1 relax relax Wl Map Wl M Some others linker options deactivate binary optimization W1 shared Wl1 shared Wl dy Wl1 Bdynamic W1 call_shared Wl export dynamic Wl E W1 dynamic linker W1 dy Wl Bdynamic W1 call_ shared Wl export dynamic Wl dynamic linker call shared shared 10 4 binopt This section describes how to invoke and use the binopt binary to perform instruction cache optimization Note The options to binopt are accessible through the st200cc driver by prefixing them with the Wo option 10 4 1 Synopsis lt tools dir gt bin binopt options input lt file in gt output lt file out gt where lt tools dir gt is the directory the toolset is installed in file inis an input executable relocatable binary for static mode real executable for dynamic mode 7 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA binopt 167 10 4 2 Options Global binopt options icacheopt Perform instruction cache optimizations deadcode Perform dead code elimination codereorder Perform code reordering from a hand written layout file input In
67. NLINE all option has been specified by the user Otherwise cost evaluation is used to decide whether to inline or not and the candidate function is rejected if its estimated cost is above a given threshold set by the compiler The INLINE 1ist on option can be used to list what is inlined STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H Inlining 5 2 2 PRELIMINARY DATA 61 Changing the compiler limits is not recommended since this can lead to longer compilation times or increased memory usage or both with no noticeable performance benefit Finally e the function to be inlined must be defined and visible in the same source file as the function using it e a static function that is inlined can be in specific circumstances considered dead and removed from the final object file st200cc inlining options Table 26 specifies the options to control the stand alone inlining More than one sub option can be specified to the INLINE option either by using colons to separate each sub option or by specifying multiple options on the command line Some INLINE sub options are specified with a setting that either enables or disables the feature To disable a feature specify the sub option with either OFF FALSE or 0 all these strings are case insensitive for example INLINE list 0FF To enable a feature either use the option name alone for example INLINE list or any other string can be used on the
68. Optimization options on page 16 Profiling options The pg option instructs st200cc to generate profiling information see Section 5 6 Profiling on page 80 Using the pg option together with g enhances the precision of the profile symbolic information Call Trace instrumentation options The finstrument functions and minstrument calls instructs st200cc to generate instrumentation calls see Section 5 7 Call trace instrumentation on page 81 Optimization options The options in Table 8 control optimization levels Option Description 00 No optimization 01 Minimal optimization 0s Optimization without code size expansion 02 Global optimization 03 Aggressive optimization Table 8 Optimize options O optimization is equivalent to 02 Os optimization applies the optimizations of 02 except for those that increase the code size such as unrolling STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Command line options 17 The options in Table 9 enable finer control of the optimization level Option Description f no strict aliasing fstrict aliasing allows the compiler to assume the strictest aliasing rules applicable to the language being compiled For C and C this activates optimizations based on the type of expressions In particular an object of one type is assumed never to reside at the same address as an object of a different type unles
69. ST200 startup files lt tools dir gt 1lib st220 le bare crtend o ST200 startup files o a elf Output binary Once steps 1 to 3 are completed an ST200 executable binary a elf is generated This can be executed in two different ways e Use the stand alone driver for the load run tool available as st200run in the following way 4 st200run target sim220 a elf This causes the a e1 ST200 binary to be interpreted by the st200run command The simulator also provides some minimal cycle counting and statistics facilities A gt A gt lt gt IIIITI RA a a AA A fy STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 7 PRELIMINARY DATA ST200 Micro Toolset interface e Use the ST200 gdb debugger 4 st200gdb nw a elf This causes the ST200 version of gdb running on the host platform to load the a elf image Once started the minimal sequence of commands to issue is gdb gt target gdi t sim220 inform gdb to use the built in simulator gdb gt load load the binary to the simulator environment gdb gt run start the execution The version of st200gdb shipped with the ST200 emulation toolchain is a fully functional debugger If the binary is compiled with the g flag source level debugging is possible Otherwise assembly level debugging is always supported for ST200 binaries The st200gdb debugger has both a graphical user interface as well as a command line
70. Toolset is mainly intended for tool developers for operating system development and for applications that require modeling interrupts and real time behavior It includes the whole set of tools that manipulate ST200 object files including the ST200 assembler compiler linker load run tool debugger and archiver Here ST200 assembler files are translated to ST200 object files that the linker merges to produce an ST200 executable image This image file does not run natively on the host workstation and requires an interpreter to be executed See Section 1 4 1 Example command lines on page 6 for details I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual ST200 Micro Toolset User Manual PRELIMINARY DATA Toolset overview Figure 1 shows the main components of the ST200 Micro Toolset c source files cxx source files ST200 C C Compiler ST200 assembler files s ST200 assembler st200as ST200 object file ST200 object file ST200 libraries target board boot and sysconf files IST200 linker st200Id ST200 binary e1 ST200 load run tool ST200 debugger st200run st200gdb Figure 1 Components of the ST200 Micro Toolset interfaces Figure 1 does not include the binary optimizer tool instruction cache placement dead code and dead data elimination nor the PFO Profiling Feedback Optimization nor the IPA Interprocedural Ana
71. _ asm addcg 0 1 2 3 4 r ui 64v_ lh 1_ b ui64v_ lh h_ 2 y t yn s h c ya return ui64v_ v_ STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H 1971 Intrinsic PRELIMINARY DATA functions 8 1 8 1 1 8 1 2 Introduction Rationale The st200cc compiler recognizes a number of intrinsic operators which can be used to produce assembly language statements that otherwise could not be expressed through standard ANSI C C These intrinsics are specified and called just like standard ANSI C C functions using standard types however they are treated specially by the compiler The ST200 intrinsics apply to the ST220 and ST231 parts Models ST200 intrinsics have been modelled as C functions which act as executable specifications This has the benefit that models can be used to develop DSP algorithms on a workstation that are immediately and safely ported to the ST220 and ST231 The implementation of the models imodels c is delivered with the current compiler distribution gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 124 8 2 8 2 1 Note 7 PRELIMINARY DATA Naming intrinsics Naming intrinsics Naming scheme STMicroelectronics intrinsics may be used for several families of DSP and micro controllers whose natural integral types are not always equivalent To accommodate a variety of targets a naming scheme h
72. ables c fy ST Microelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 78 Data prefetching The following code gives a further ezample of prefetching extern int A 160 int foo void int i int sum 0 for i 0 i lt 160 i sum A il return sum The compiler s loop unrolling optimization first unrolls this by a factor of 8 to give extern int A 160 int foo void int i int sum 0 for i 0 i lt 160 i 8 sum A il sum A i 1 sum A i 2 sum A i 3 sum A i 4 sum A i 5 sum A i 6 sum A i 7 return sum After the unrolling the compiler inserts prefetch operations to give code equivalent to extern int A 160 int foo void int i int sum 0 for i 0 i lt 160 i 8 sum A il sum A i 1 sum A i 2 hi ST Microelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Data prefetching 79 sum A i 3 sum A i 4 sum A i 5 sum A i 6 sum A i 7 __builtin_prefetch amp A i 16 return sum 5 5 3 Advanced data prefetching options By default the prefetch instructions inserted read two cache lines ahead of the current array reference This behavior may be adjusted by using the command line option LNO prefetch _ahead n where n is the number of cache lines to read ahead For example LNO prefetch_ahead 0 50 2 where
73. ages are e Warning pragma LOOPTRIP inconsistent with computed value ignored e Warning pragma LOOPTRIP not followed by a loop ignored e Warning malformed pragma looptrip n pragma pipeline This pragma is used to override pipelining and renaming defaults on a particular loop This is a 03 optimization and the defaults are pipelining 3 and renaming 2 With pipelining 3 the maximum performance software pipeline is built with possible code increase Using pipelining 1 and renaming 1 may reduce code size The meaning for pipelining is as follows e pipelining 0 no loop iteration overlap e pipelining 1 maximum overlap over 1 iteration e pipelining 2 maximum overlap over 3 iterations e pipelining 3 maximum overlap over 7 iterations The meaning for renaming is as follows I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 56 Loop optimization pragmas e renaming 0 no register renaming e renaming 1 register renaming enabled e renaming 2 local register modulo renaming 4 2 7 Code generation pragmas pragma loopseq READ pragma loopseq WRITE This pragma instructs the compiler that the memory READ accesses or respectively the memory WRITE accesses as they appear in the loop should be sequenced This is not an assertion that the accesses must be kept in sequence for instance this is not a replacement for volatile accesses where it is
74. al ADCS 7508723H 1971 Optimization PRELIMINARY DATA guide 5 1 5 2 1 Introduction This chapter describes specific compiler options and techniques that can be used to gain maximum performance in your application Inlining Inline function expansion is performed for function calls that the compiler estimates to be frequently executed These estimations are based on a set of heuristics The compiler might decide to replace the instructions of the call with code for the function itself inline the call The compiler supports both the single file inlining mode as described in Section 5 2 1 and cross file inlining through the IPA optimization described in Section 5 9 Interprocedural analysis optimization IPA on page 86 Single file inlining The purpose of this section is to make users aware of the underlying algorithms used to select functions to inline First it describes how possible candidates are selected for inlining and how the selection is finalized taking size conditions into account Then user level compiler switches are listed to show how the inlining process can be controlled The inlining decisions of the compiler can be observed with the INLINE list option it is recommended that this option should be used when tuning inlining decisions I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 60 57 PRELIMINARY DATA Inlining There are two kinds of candidates for inlining
75. ame register to an input operand and to a non early clobber output operand 7 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Introduction 121 7 1 3 7 1 4 Volatile The volatile syntax is as follows asm volatile template output operands input operands clobber list or __asm__ volatile template output operands input operands clobber list The volatile keyword indicates that an instruction has side effects A volatile statement will not be deleted if it is reachable The order of volatile asm statements and or other volatile accesses will be preserved A consecutive sequence of volatile asm statements may not stay perfectly consecutive since some other instructions may be scheduled in between To achieve the effect of keeping instructions perfectly consecutive use a single asm instruction An asm statement without any operand or clobbers will be treated identically to a volatile asm statement the same as for an asm statement without an output operand Scheduling considerations On the ST220 processor scheduling considerations must account for the absence of hardware interlocks The programmer must make sure that all asm outputs are available in the next cycle following the asm for instance by adding explicit possibly empty bundles On the ST231 processor this is not necessary as this processor is interlocked Generating different schedules for these differen
76. an be requested from the compiler to notify potentially erroneous or dangerous C program constructions Table 6 lists a subset of the GCC options Option Description Wall Enables all warnings w Disables all warnings Werror Turns warnings into errors pedantic Issues all warnings needed by strict ANSI C compliance pedantic error Turn all pedantic warnings into errors Table 6 General warning options I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 14 Command line options The options in Table 7 take a positive form a negative form can be systematically constructed by changing the w prefix to a Wno prefix for example Wnoformat Option Wchar subscripts Description Warn if an array subscript has type char Wformat Wimplicit int Wimplicit function declaration Werror implicit function declaration Wimplicit Wmissing braces Wparentheses Check calls to the printf and scanf family of library functions Check that all declarations specify a type which is int by default in c89 Warn when a function is used but not declared Output error when a function is used but not declared Wimplicit int and Wimplicit function declaration Warn if an aggregate or union initializer is not fully bracketed Warn if parentheses are omitted in certain contexts Wreturn type Warn when a function is defined with a retu
77. analysis 2 2 15 Symbol visibility specification 2 2 16 Sending options to a specific phase 2 2 17 Specifying the run time environment 2 2 18 Selecting the endianness 2 2 19 Configuration options 2 2 20 Directory and library options 2 2 21 Environment variables 2 3 Predefined macros 2 4 C99 support st200c 3 1 Introduction to st200c 3 1 1 References 3 2 Getting started 3 2 1 Invoking the compiler 3 2 2 Input and output 3 3 C specific command line options 3 3 1 C dialect options 3 3 2 C specific warning options 3 3 3 Code generation options 3 3 4 Directory and library options STMicroelectronics ST200 Micro Toolset User Manual 13 13 16 16 16 16 17 19 20 20 20 20 21 21 22 22 23 24 24 27 31 31 31 32 32 32 39 33 33 34 36 ADCS 7508723H 34 3 5 3 6 3 7 3 8 3 9 3 10 3 11 PRELIMINARY DATA Predefined macros GNU C language extensions 3 5 1 Extensions to the C language 3 5 2 Variable functions and type attributes 3 5 3 Built ins GNU C asm statement Standard Template Libraries STL support 3 7 1 Standard headers status 3 7 2 Supported extension headers 3 7 3 Supported backward compatibility headers 3 7 4 Identifying the STL version RTTI notes Exceptions notes Checking operator new return value Known limitations 3 11 1 Status of the known limitations 4 Pragmas 4 1 4 2 4 3 ADCS 7508723H Pragmas short description and syntax Loop optimiz
78. and data removal is activated It contains list of symbols data and functions removed It also contains some statistics about saved space This file is generated when the keep option of st200cc is used Table 58 st200cc binopt optimization files a To use the TracePlugin plug in for example to invoke st200run to run the simulator on a Unix host use a command similar to the following st200run d st200sim 220 MODE ISS TRACING ON true TRACE PLUGIN MODULE lt tools dir gt host tplugins TracePlugin OUTPUT TRACE FILE file dt executable lt tools dir gt is the directory where the toolset is installed See the ST200 Cross Development Manual for further details about st200run ADCS 7508723H Lia STMicroelectronics ST200 Micro Toolset User Manual PRELIMINARY DATA 156 st200cc options 10 2 st200cc options The following key options are interpreted by st200cc icache opt value Enables or disables ICache optimization value may be set to on for enable or off for disable This option is implicitly turned on by the st200ce optimization options 02 or higher All other ICache optimization options are controlled by this option icache mapping Turns on function reordering based on a user specified file ly This is done in several steps e inthe assembly phase the assembler is requested to emit all relocations e in link phase several steps are performed apre link phase generates a relocatable image of th
79. anged with the icache algo option Then it generates an optimized relocatable image from the function layout file and the relocatable image A final link phase maps the optimized relocatable file to an executable _ H _WMH ST Microelectronics ST200 Micro Toolset User Manual ADCS 7508723H st200cc options PRELIMINARY DATA 159 icache algo algorithm Controls the placement algorithms used by static or profile based for ordering algorithm may take the values ph col trg or ltrg ADCS 7508723H algorithm ph This is the default Enables a placement that optimizes main memory spatial locality of the code by implementing PH90 There is no code size impact with this algorithm algorithm col Optimizes main memory spatial locality with the knowledge of cache configuration to avoid cache conflicts The implemented algorithm is HKC96 This algorithm may increase code size It should be used for applications that have a large code covering cache size ratio gt 2 algorithm trg Enables a more optimal placement for minimization of cache conflicts at the cost of large code size increase This implements the GBSC97 algorithms and only works with profile based option It uses temporal information from the profiling trace algorithm ltrg Enables a near optimal placement for minimization of cache conflicts at the cost of large code size increase It should be used with caution or for experiments It
80. ansion See also forcedepth space and plimit IPA multi_clone n Specifies the maximum number of clones that can be created from a single procedure By default this value is 0 Aggressive procedure cloning may provide opportunities for inter procedural optimization but it also may significantly increase the code size IPA node_bloat n When used in conjunction with IPA multi_clone this specifies the maximum percentage growth of the total number of procedures relative to the original program IPA plimit n Stops inlining into a particular subprogram once it reaches size n in the intermediate representation The default is 2500 IPA space n Stops inlining when the program size has increased by n For example n 20 limits code expansion due to inlining to approximately 20 The default is 100 IPA specfile filename Opens filename to read more options A spec file contains zero or more of the options allowed by IPA Table 29 Advanced IPA options 5 9 4 Limitations The IPA optimization is not compatible with the g compiler option The IPA optimization is currently not supported with the PFO optimization see Section 5 8 on page 83 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Symbol visibility specification 89 5 10 Symbol visibility specification Note Command line options are provided to control symbol visibility These options are useful in
81. are exclusive Parameter type Values Description Core identification st220 st231 Defaults to st 220 if not already specified in the assembly file or by the mcore command line option Note this directive does not impact the encoding table used by the assembler only the ELF flags Silicon implementation cuto cutl cut2 Defaults to cuto if not already identification cut 3 cut4 cut5 specified in the assembly file Software ABI convention no abi Defaults to no abi if not already old multiflow abi specified in the assembly file 1x embedded abi pic abi gcc abi OS ABI identification bare machine Defaults to bare machine if not os21 already specified in the assembly linux file Table 59 assume directive parameters hi ST Microelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Assembler syntax 191 Proc parameters This directive is supported for compatibility reasons with existing code The parameters are ignored endproc parameters This directive is supported for compatibility reasons with existing code The parameters are ignored type symbol object function moveable Declare the symbol to be either the name of an object or a function If moveable is specified it can be moved around by the ICache optimizer 11 2 9 7 ST200 special directives The following directives are generated by the compiler but are ignored by the assembler In most cases they
82. as been designed which takes into account this variety An intrinsic has basically a generic name containing its signature return_type _ operation _ arguments_types Intrinsics are given shorter and more mnemonic alias names for each target taking into account the natural names of types on the specific target For instance the natural name of the 32 bit integer on the ST200 is word so the intrinsic that realizes the clamped addition of two 32 bit integers is named int32_addc_int32_int32 in its generic form and __addew in its ST200 form Where the addc part denotes the clamped addition operator and w the fact that the result is of word type The presence of the two leading underscores on each name denotes according to the ISO IEC 9899 C Standard that no such name should be defined by the user More specifically All identifiers that begin with an underscore and either an upper case letter or another underscore are always reserved for any use STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Naming intrinsics 125 Finally the International Telecommunication Union ITU and European Telecommunications Standard Institute ETSI basic operators have their own naming scheme thus they must be explicitly mapped onto ST200 intrinsics This is explained further in Operations on page 127 8 2 2 Building intrinsic names This section elaborates on the rules for building intrinsic names
83. ation pragmas 4 2 1 pragma unroll 4 2 2 pragma ivdep 4 2 3 pragma loopdep 4 2 4 pragma loopmod 4 2 5 pragma looptrip 4 2 6 pragma pipeline 4 2 7 Code generation pragmas 4 2 8 Heuristic pragmas Miscellaneous pragmas STMicroelectronics 36 38 38 38 39 39 39 40 41 42 43 43 44 44 46 46 gj ST200 Micro Toolset User Manual PRELIMINARY DATA vi 4 3 1 pragma ident 58 4 3 2 pragma weak 58 5 Optimization guide 59 5 1 Introduction 59 5 2 Inlining 59 5 2 1 Single file inlining 59 5 2 2 st200cc inlining options 61 5 2 3 Extern inline functions 63 5 2 4 Inlining pragmas 63 5 3 Memory dependences in C programs 69 54 Aliasing rules in C C programs 71 5 5 Data prefetching 75 5 5 1 Manual data prefetching 76 5 5 2 Automatic data prefetching 76 5 5 3 Advanced data prefetching options 79 5 6 Profiling 80 5 7 Call trace instrumentation 81 5 7 1 Instrumenting functions finstrument functions 81 5 7 2 Instrumenting call to functions minstrument calls 81 5 8 Profiling feedback optimization PFO 83 5 8 1 Principles 83 5 8 2 Command line 83 5 8 3 Example 84 5 8 4 What feedback does 85 5 9 Interprocedural analysis optimization IPA 86 5 9 1 Introduction 86 5 9 2 Using IPA 86 5 9 3 IPA command line options 87 5 9 4 Limitations 88 5 10 Symbol visibility specification 89 hy STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA 5 10 1 Introducti
84. ator priorw int16_prior_int16 DSP operator priorh __int16_norm_int64 ETSI norm norml _ int16_norm int32 ETSI norm normw Table 47 Miscellaneous intrinsics g ST200 Micro Toolset User Manual PRELIMINARY DATA 140 Intrinsic functions summary Intrinsic Purpose ST200 name __int16_norm_int16 ETSI norm_s normh __uint16_lzcnt_int64 DSP operator _ lzcntl uint16_lzcnt_int32 DSP operator __lzentw __uint16_lzcnt_int16 DSP operator _ lzcnth Table 47 Miscellaneous intrinsics Intrinsic Purpose ST200 name int16_clamp_int32 ETSI saturate _ clampwh __int16_near_int32 IEEE round __nearwh int16_nearc_int32 IEEE round and nearcwh clamp int16_round_int32 DSP operator _ roundwh int16_roundc_int32 ETSI round __ roundcwh __int32_puth_int16 DSP operator __puthw __int32_putl_int16 DSP operator _ putlw __int16_geth_int32 ETSI extract_h gethh _ int1l6 getl int32 ETSI ertract _ getih Table 48 Clamp round insert and extract intrinsics Intrinsic Purpose ST200 name uint32_bitclr_uint32_uint16 DSP operator __bitclrw __uint16_bitclr_uint16_uint16 DSP operator __bitclrh __uint32_bitset_uint32_uint16 DSP operator __bitsetw uint16_bitset_uint16_uint16 DSP operator __bitseth uint32_bitnot_uint32_uint16 DSP operator __bitnotw Table 49 Bit manipulation intrinsics hy STMicroelectronics ST200 Micro Toolset User Manual
85. being compiled the aliasing rules are stated in clause 6 5 7 of the ISO IEC Standard Expressions For C and C this activates optimizations based on the type of expressions In particular an object of one type is assumed never to reside at the same address as an object of a different type unless the types are almost the same For example an unsigned int can alias an int but not a void or a double A character type may alias any other type By default the fno strict aliasing option is used for legacy reasons However in future releases the fstrict aliasing will be used by default for o optimization levels Particular attention is required before reporting any compiler issue when using fstrict aliasing specifically when code runs correctly with the default compiler but diverges when strict aliasing is used This is often caused by a violation of aliasing rules which are part of the ISO C C standard These rules say that a program is invalid if you try to access a variable through a pointer of an incompatible type gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 72 Note Note 57 PRELIMINARY DATA Aliasing rules in C C programs The example shown in Figure 2 demonstrates this violation where a float is accessed through a pointer to integer include lt stdio h gt int main int argc char argv float a 0 0f int pa int sa pa 0x40000000 violation
86. cache static o opt_exe c or 2 phases compilation frequency estimation heuristic st200cc 02 c c link repeat CFLAGS st200cc 02 o opt_exe o or 2 phases compilation frequency estimation heuristic st200cc icache opt on icache static c c link repeat CFLAGS st200cc icache opt on icache static o opt_exe o 9j STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 1 64 PRELIMINARY DATA Examples 10 3 2 Compiling a relocatable object with static Cache optimizations This is useful for libraries lib_stat is the main function of the library algorithms use this function as the root of the static call graph st200cc c icache opt on icache static o lib o v Wl1 r Wo begin Wo 1lib start use the archiver to produce the lib a from lib o st200 ar rc lib a lib o or st200cc c icache opt on icache static c st200cc o icache opt on icache static o lib o W1 r Wo begin Wo lib start st200 ar rc lib a lib o 10 3 3 To keep a generated layout file st200cc icache opt on icache static o opt_exe keep c Wo v v The generated file opt_exe ly contains the computed layout file This layout can then be forced with st200cc icache opt on icache mapping opt_exe ly o opt_exe c Wo v v 10 3 4 Using profile driven ICache optimizations ky st200cc icache opt on c c First link st200cc icache opt
87. ce code size This option is intended to be used by OS or library writers and should not be used by the general user Dismissible load generation is enabled by default fverbose asm The fno verbose asm removes extra commentary information in the generated assembly code fno verbose asm The default is to have verbose asm output Table 10 Code generation options 2 2 11 OPT options The options OPT unroll_size OPT cray_ivdep and OPT liberal_ivdep modify the behavior of pragmas and are documented in Section 4 2 1 pragma unroll on page 49 and Section 4 2 2 pragma ivdep on page 50 The OPT alias option is documented in Section 5 3 Memory dependences in C programs on page 69 iy ST Microelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 20 Command line options 2 2 12 Data prefetching options The option mauto prefetch triggers automatic data prefetching which is documented in Section 5 5 Data prefetching on page 75 2 2 13 Inlining options The inline noinline and INLINE options are provided to control inlining of functions They are listed in Table 26 on page 61 and Table 27 on page 62 and described in Section 5 2 1 Single file inlining on page 59 Only functions marked with the inline keyword are subject to inlining unless specified otherwise 2 2 14 Interprocedural analysis The ipa option enables interprocedural analysis and is described in Section 5 9 on
88. cognized input file is passed down to the link phase Input and output File extension naming conventions are summarized in Table 16 Extension Convention CXX CDp c C language source file to be pre processed and compiled C CC CPP CXX ii C language source file already pre processed Table 16 Input names conventions The final executable file does not need to have a specific file extension If no output file name is specified through the o option the executable generated is a out Examples st200c file cxx generates the executable a out st200c file cxx o file u generates the executable file u STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA C specific command line options 33 3 3 C specific command line options 3 3 1 C dialect options The option std value instructs the compiler front end to select the appropriate C language dialect to use Possible value for std are listed in Table 17 Option Description std c 98 Default if fansi Set language to ISO IEC 14882 std gnu 98 Default Set language to ISO IEC 14882 and support GNU extensions Table 17 C dialect options 3 3 2 C specific warning options Diagnostic messages can be requested from the compiler to notify potentially erroneous or dangerous C program constructions Table 18 lists a subset of the GCC options Option Description W
89. ct po file 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA st200cc options 161 10 2 3 Option combinations Ifthe icache static icache mapping and icache profile options are used together on the same command line each specified optimization is taken as far as possible while they do not compete When they compete icache mapping has first priority icache profile has second priority and icache static has the lowest priority of the three options If the file specified with icache mapping or icache profile does not exist the option is ignored When combining Cache optimization and dead code and data removal BINOPT phase makes both optimizations at once Dead code and data removal is first executed then ICache optimization is completed on the lightened code This means that dead functions do not pollute ICache optimization 10 2 4 Full optimization For the most efficient function layout optimization the run time libraries must be compiled with the icache opt and icache static options Alternatively the global optimization option 02 or higher must be used This applies to both the standard libraries provided with the sT200 toolchain and to user libraries Dead code and data optimization also needs to compile libraries with deadcode or 02 or higher options because only code assembled by a special option of st200as emit all relocs can be removed 10 2 5 R
90. d any symbol in the input object file e Cannot remap symbol s as requested in the link mapping symbol not found with unknown size or already placed warning a function cannot be moved e input mapping file s is in wrong format warning syntax error in the reordering input file 1y Ignore this file output object file is a copy of input e no relocation found just copying warning cannot find any relocation so reordering is impossible Output object file is a copy of input gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 174 PRELIMINARY DATA References 10 6 References 7 COL Efficient Procedure Mapping Using Cache Line Coloring Hashemi Kaeli amp Calder 1996 WRL Research Report 96 3 GBSC97 Procedure Placement Using Temporal Ordering Information NiKolas Gloy Trevor Blackwell Michael D Smith and Brad Calder IEEE 1997 HKL96 Efficient Procedure Mapping using Cache Line Coloring Air H Hashemi David R Kaeli and Brad Calder WRL Research Report 96 3 1996 BINOPT Optimization at binary level Binary name is binopt This utility performs instruction cache optimization dead code and data removal It includes old codereorder and icacheopt tools LTRG An algorithm inspired from TRG using a multi graph that represents exactly cache conflicts PH90 Profile Guided Code Positioning Karl Pettis and Robert c Hansen ACM 199
91. d identifications values 57 compiler patch level Table 14 Predefined macros STMicroelectronics ST200 Micro Toolset User Manual Name Default definition Purpose See also __open64__ Defined Compiler technology identification __GNUC__ 2 Front end major no gec release identification GNUC_MINOR 95 Front end minor no gcc release identification __ T200CC__ Defined value Compiler depends on major identification compiler version __ T200CC_MINOR__ Defined value Compiler depends on minor identification compiler version __ T200CC_PATCHLEVEL__ Defined value Compiler depends on identification ADCS 7508723H PRELIMINARY DATA Predefined macros 25 Name Default definition Purpose See also _ sT200CC DATE __ Defined value Compiler depends on identification compiler release date ST200CC VERSION __ Defined valueisan Compiler identification string identification sT200 Defined Architecture identification _sT200__ Defined Architecture st200 identification _ sT220__ Defined by default Architecture mcore st220__ and when identification mcore st220 _ ST231__ Defined when Architecture mcore st231 mcore st231 identification _ LITTLE ENDIAN__ Defined by default Endianness EL and when using the identification EL option BIG_ENDIAN Defined by the EB Endianness EB option identification _LANGUAGE_C Defined for C Language source currently processed i
92. d relocatable file to an executable gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 158 st200cc options icache profile file dt Turns on profile based function layout The file dt drives the function placement algorithm If file dt does not exist the optimization is skipped and the following message warning is emitted by the driver profile file not found profile and relink your application Profile based function layout has the following steps e In assembly the phase the assembler is instructed to emit all relocations e The link phase is split into several phases Apre link phase generates a relocatable image of the executable An optimization and trace analysis phase BINOPT generates the function layout file based on the file dt This phase needs the original binary to build the symbol table and match addresses of the trace file with the function name This binary is passed to this phase with the icache profile exe exe option of the st200cc driver If this option is omitted the file specified with the o exe option to st200cc is used In this case this file is overwritten by the final link phase If the exe file does not exist or a out if omitted icache profile is ignored Coherence between file dt and the original binary exe is checked by the dates of these two files file dt must be more recent than exe The algorithm used for the function layout can be ch
93. definition define MESSAGE Hello good brave new World would be written under ISO define MESSAGE Hello n good brave new World n 9j STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 106 Extensions to the C language family 6 2 15 Non Lvalue arrays may have subscripts In ISO C99 arrays that are not lvalues still decay to pointers and may be subscripted However they may not be modified or used after the next sequence point and the unary operator amp may not be applied to them struct foo int a 4 struct foo static const struct foo f 2 4 8 16 return f void bar void int i for i 0 i lt 4 i printf f a dl d n i f a lil int main int argc char argv bar a 0 15 bar return 0 6 2 16 Arithmetic on void and function pointers In GNU C addition and subtraction are supported by pointers to void and by pointers to functions size used for a void or of a function is 1 sizeof is allowed for void and for a function it returns 1 void f0 void void p 0 void pf void 0 bar void p pf printf sizeof void d n sizeof void printf sizeof func d n sizeof f0 7 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Extensions to the C language family 107 6 2 17 Non constant initializers As
94. directive int ig 0 int jg 0 inline void f1 int i ig i inline void 2 int i jg j void main pragma noinline function f1 1 1 1 is not marked for inlining 2 1 2 is candidate to inlining pragma inline next f1 1 2 f1 is forced to be inlined pragma noinline_next 2 2 3 2 is not marked for inlining pragma defaultinline f1 1 4 1 is candidate to inlining printf result is d d n ig jg Example 4 This example illustrates the use of several function names or an empty name list with pragma directives pragma noinline file int f int i return i 1 int g int i int j i i is not marked for inlining pragma inline next f g j i is forced to be inlined g is ignored j f i 1 5 is not marked for inlining return Jj int h int i pragma noinline next int j i i g i and g are not marked for inlining pragma inline next f g j i i g i and g are forced to be inlined return j Ij STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 68 7 PRELIMINARY DATA Inlining void main g and h are not marked for inlining printf result is d d n g 0 h 0 Example 5 This example illustrates the use of the noinline attribute and shows how the attribute has precedence over pragma pragma inline file 3 int ig 0
95. ds funsigned bitfields fno signed bitfields fno unsigned bitfields Command line options Description fsigned char implements type char as signed funsigned char implements char as unsigned Note that when the funsigned char option is used the ___CHAR_UNSIGNED__ preprocessor symbol is defined The compiler default is signed These options control whether a bitfield is signed or unsigned when the declaration does not use either signed or unsigned The compiler default is signed ffixed reg lt register list gt lt register list gt is a list of one or several comma separated register names or dash separated register ranges either general purpose registers or boolean registers The syntax used for a general register is ri where i can be 0 to 63 and bj where j can be from 0 to 7 This option makes the given registers fixed registers that is the code generated by the compiler never uses them There are however some registers that are used by the compiler for ABI register conventions See the table of general registers in the ST200 Run time Architecture Manual Those registers with a specified use must not be reserved with this option Note that specific care must be taken when using this option since low level library and run time support code are not specifically built to support non ABI register usage For instance reserving the r62 register does not prevent the already compiled librar
96. e executable po file areordering phase BINOPT generates the optimized relocatable op file from the input file file ly and the relocatable image a final link phase maps the optimized relocatable file to an executable 7 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA st200cc options 157 icache static value Enables or disables static analysis based function reordering value may be set to on for enable or off for disable When this option is set to on a new elf section profile_ info is created This section contains frequency estimation of call counts These sections are present only in po and op object file The linker removes this section in the final link phase Static analysis is done in several steps e In the compiler back end estimated block frequencies are emitted in a special section e In the assembly phase the assembler is instructed to emit all relocations e The link phase is split into several phases Apre link phase generates a relocatable image of the executable po file An optimization phase BINOPT generates the function layout file 1y file based on estimated block frequencies The algorithm used for the computation of function layout can be changed with the icache algo option Then it generates an optimized relocatable image from the relocatable image and the function layout file 1y A final link phase maps the optimize
97. e The dot symbol The special symbol refers to the current address that is being assembled Therefore the expression here long defines the location here to contain its own address Assigning a value to is treated the same as a org directive This means that the statement 4 is the equivalent to skip 4 discussed later e Value The value of a symbol is defined as a 32 bit 2 s complement number For a symbol which labels a location in the text data or bss sections the value is the offset in bytes from the start of the section to the label 7 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Assembler syntax 181 11 2 5 Expressions An expression specifies an address or numeric value An expression consists of one or more arguments delimited by operators The arguments of an expression are symbols numbers or sub expressions 11 2 5 1 Sub expressions A sub expression is either an expression within parentheses or a prefix operator followed by an argument Example 3 foo 3 11 2 5 2 Absolute expressions An expression that can be evaluated to a value without knowledge of addresses one that is not relative to the start of some object section is called absolute Expressions that are not absolute have the form section offset where section is typically one of text data bss or undefined and offset is an offset into the section a sig
98. e_function function Function pragma inline_file function File pragma noinline_file function File pragma defaultinline function Table 25 st200cc pragmas a This column denotes the lowest optimization level for which the pragma has an effect For example 00 means the pragma is applicable even when optimization is switched off A list of optimization levels is given in Section 2 2 9 Optimization options on page 16 b All inlining pragmas are described in Section 5 2 4 Inlining pragmas on page 63 7 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Loop optimization pragmas 49 4 2 Loop optimization pragmas 4 2 1 pragma unroll This pragma suggests to the compiler the type of loop unrolling that should be done The pragma is a recommendation to the compiler to add n 1 copies of the loop body to the inner loop The value of n must be at least 1 If it is 1 then unrolling is not performed If the loop that this pragma immediately precedes is an inner loop then it implies standard inner loop unrolling Inner loop unrolling example for i 0 i lt 10 i pragma unroll 2 for j 0 j lt 10 j a i j ali 31 b i1 31 becomes for i 0 i lt 10 i for j 0 j lt 10 j 2 afil jl a i j b i1 315 a i j 1 a i j 1 b i j 1 If the loop that this pragma immediately precedes is an outer loop that
99. ect file that implements the two functions above to link correctly Instrumenting call to functions minstrument calls The minstrument calls is not a standard GCC option Using this option generates instrumentation calls just before and just after each function call gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 82 57 PRELIMINARY DATA Call trace instrumentation The following profiling function is called with the address of the caller function and the address of the callee function void profile call void caller fn void callee fn const char caller_name const char callee_name int event The first argument is the address of the start of the current function the caller function which may be looked up specifically in the symbol table The second argument is the address of the start of the called function the callee function which may be looked up specifically in the symbol table The third argument is the name of the caller function The fourth argument is the name of the callee function or NULL if the call is an indirect call The function names passed in the third and fourth arguments are pointers to static strings that have the lifetime of the instrumented executable or shared object The function names are the mangled names in C The fifth argument is 0 when this function is invoked just before a call instrumenting a function entry It is 1 when this function
100. ecutable is run usually with a representative training input set that information is stored in a unique file called name instro An unique file is generated for each execution The st200cc command line option to specify the feedback files to be used is fb lt name gt All files with the name name instro0 will be combined 5 8 3 Example Step 1 Instrument the program to set it up for running a test set with profiling tests enabled To do this compile the program with the fb create name This option inserts code into the program so it can track which spots of the code are used often when the program is run for example how many times a branch is taken or how many times a loop iterates The library libinstrC a is automatically linked with the program st200cc fb_ create fbtest o ftest ftest c Step 2 Run the program with some sample input When the program executes statistics are generated and written to files for later use The instrumented program runs significantly slower than usual This creates a file of frequency data named fbtest instr0 The 0 in instr0 indicates that instrumentation occurred before Very High Optimization VHO lowering which is the very first optimization of the back end compilation process Eventually it should be possible to instrument at a variety of stages but this is not activated for the moment Multiple runs can be performed using different input data to generate multiple fr
101. ed without declaring the visibility attribute in the header file The file mylibrary v see Figure 8 can replace the config h file The user then compiles with the options mvisibility decl mylibrary v fvisibility hidden Visibility specification for mylibrary protected symbols in the interface initialize process finalize Figure 8 mylibrary v Another more advanced usage is to explicitly define all the symbols that are outside of the library all the symbols that are part of the library interface and let all other symbols be local to the library STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Symbol visibility specification 93 For instance ifthe user knows the list of symbols that are used by the library but are external to the library for example printf and malloc the specification file mlibrary_all v shown in Figure 9 can be used to compile with the command line option mvisibility decl mlibrary_all v Visibility specification for mylibrary default symbols usable outside of the library printf malloc protected symbols in the interface initialize process finalize hidden all other symbols are kept local ko Figure 9 mylibrary_all v With the mylibrary_all v visibility specification the library designer asserts the following 1 No symbol other than printf malloc can be referenced from the library without being defi
102. elocatable files The r option to the linker which can be used to generate a relocatable file is compatible with ICache optimizations In this case r option is passed to the final link phase and the optimized relocatable object is generated The r option deactivates the dead code and data removal optimization Indeed when building a relocatable object binopt cannot see the whole application some symbols may be undefined and resolved later gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 162 PRELIMINARY DATA st200cc options 10 2 6 Shared libraries call shared executable Note The dynamic mode shared call shared options which can be used to generate a shared library or an executable dynamically linked to shared libraries is not compatible with binary optimizations Binary optimization requires an intermediate relocatable object to be built which could not be later transformed into a dynamic object Shared libraries and call shared executables are not supported by this release 10 2 7 Passing other options to the optimization phase 57 The Wo option can be used to pass specific options to the optimization phase BINOPT For example e Wo sizecacheline 64 Wo cacheline 512 These options set the configuration cache to 64 bytes x 512 lines e Wo begin my_main These options activate the instruction cache optimization for my main function only It is possible to enhance
103. ematically constructed by changing the W prefix to a Wno prefix for example Wnoformat 3 3 3 Code generation options The options in Table 19 control various aspects of the code generation Option no rtti f no exceptions Description Enable or disable generation of rtti information Enable or disable exception handling f no check new no implicit templates no access control Check that the pointer returned by operator new is non null before attempting to modify the storage allocated or calling the object s constructor Emit code or never emit code for non inline templates which are instantiated implicitly Turn on or off all access checking Table 19 C code generation options 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA C specific command line options Option no elide constructors 35 Description Omit creating a temporary which is only used to initialize another object of the same type fno elide constructors forces the compiler to call the copy constructor even when it could be optimized out f no for scope Under fno for scope the scope of variables declared in a for init statement extends to the end of the enclosing scope Under ffor scope the scope of variables declared in a for init statement is limited to the for loop itself as specified by the C standard The defa
104. embler can also be invoked by running the C compiler with an input file that has a S suffix This allows the C pre processor to be used See Chapter 2 st200cc on page 9 for details Command line options This section gives a more detailed description of the command line options of the assembler Options may appear in any order and may be before after or between file names The order of file names is significant a hls file Enable listings Enable listing output from the assembler The option a requests high level assembly and symbols listing ah requests a high level language listing al requests an output program assembly listing as requests a symbol table listing The letters after a may be combined into one option for example als a file sends the listing output to file EB Generate big endian object code EL Generate little endian object code This is the default I Include file search path Add a path to the list of directories that st200as searches for files specified in include directives 1 may be used multiple times to include a variety of paths The current working directory is always searched first after that st200as searches any 1 directories in the same order as they were specified left to right on the command line STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H Invoking the assembler PRELIMINARY DATA 193
105. equency data files Runs can be executed either on simulators or hardware the only restriction is to have access to the host file system st200run tsim ftest 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Profiling feedback optimization PFO 85 Note 5 8 4 Step 3 Re compile the program with the fb name option This tells the compiler that it has some sample statistics from which it can optimize code better It then uses these statistics to compile a new program that is better tuned for the input Feedback data will be read and combined from all files with names fbtest instrO It is necessary to delete obsolete feedback data files for instance if the code is changed or use a different feedback file name for instance to evaluate enhancements on various data sets st200cc fb fbtest o ftest ftest c What feedback does Feedback collects frequency counts on control flow such as branches loops and procedure calls Memory accesses are not counted During the instrumentation step the compiler inserts extra code into the original code The inserted code consists of procedure calls to libinstrC a routines which gather control flow data such as the number of times a branch is taken or not taken how many times a loop iterates or how many times procedures are invoked When the instrumented binary is invoked on the test data the program performs as normal except
106. eral division and modulus built ins that ezpand toa loopless seguence of instructions to compute the result of the integer division or modulus operands for signed or unsigned integers These built ins only exist for the integer division or modulus operator __builtin divw __builtin divuw __builtin modw __builtin moduw The benefits are that the division operators do not suffer from instruction call penalties and possible related ICache conflicts and that other instructions can be scheduled at the same time to maximize resource usage The drawback is that contrary to the library version these operators do not minimize the number of iterations whereas the library version considers the respective magnitude of the operands to minimize the division cycles when beneficial Note These division and modulus operators should not be used when the divisor is a constant since the compiler emits efficient inline code when the constant is a power of 2 Table 57 summarizes the properties of these built ins Name Instructions critical path _ builtin divw 88 41 _ builtin divuw 76 39 _ builtin _modw 77 40 _ builtin moduw 78 39 Table 57 ST231 intrinsics properties These built ins incur a high cost in code size and should probably be inlined only in critical inner loops hy ST Microelectronics ST200 Micro Toolset User Manual ADCS 7508723H y Y PRELIMINARY DATA Compiler bugs 9 1 Introduct
107. ernal visibility for some symbols though it must be done very carefully as in this case no link time static or dynamic error occurs if the symbol is passed to another module thus violating the internal property This must only be done in cases where the library designer is sure that an address is not passed outside of the library J 5 10 4 The visibility specification file 57 The visibility specification file resembles the version script files used by the GNU linker except that it specifies all levels of visibility instead of only the global and local properties The specification file has the following BNF grammar as shown in Figure 10 with the additional notion that the denotes a range for instance a z represents all characters from a to z inclusive visibility spec visibility decls visibility decls visibility decl visibility decl VISIBILITY pattern _decls pattern decls pattern_decl pattern _decl lang _decl symbol_decl lang_decl extern LANGUAGE symbol decis symbol decls symbol decli symbol decl PATTERN VISIBILITY default protected hidden internal LANGUAGE EN gn C CHEM PATTERN a z A Z 0 9 _ 1 Figure 10 Visibility specification file BNF STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Symbol visibility specification 95 The PATTERN is a simplif
108. essions allow complicated C statements to be written and used as if they were a simple C expression optionally returning a result value Local declarations and labels may be embedded This provides a way to construct a safe preprocessor macro that comprises several statements without using the do while 0 trick that swallows the semi colon define cfoo int y foo int z if y gt 0 z y else z y z yr STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Extensions to the C language family 6 2 2 Locally declared labels 99 When GNU extensions are used in conjunction with expression statements and macros they enable service labels to be used that is labels whose scope is limited to the current statement For example define SEARCH array max target __label_ found typeof target SEARCH target typeof array _SEARCH array int i j int value for i 0 i lt max i for j 0 j lt max j if SEARCH array i j value i goto found value 1 found value 6 2 3 Labels as values target array SEARCH target AO 40101017 Y Y Y Y 1 The address of a label defined in the current function or a containing function can be obtained with the extended amp amp unary operator const char cgoto int i void ptr amp amp 00 static void array amp amp foo amp amp
109. etch applied to them 9j STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 118 Attributes 7 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H 1971 GNU ASM 7 1 7 1 1 Note PRELIMINARY DATA Introduction st200cc compiler accepts extended inline assembly asm as part of C programs This chapter only summarizes the main features of the asm implementation and describes its limitations it is not a substitute for the GNU documentation Syntax asm template output operands input operands clobber list or __asm__ template output operands input operands clobber list template the assembler instruction defined as a string constant e output operands a list of comma separated output operands input operands a list of comma separated input operands e clobber list a list of comma separated clobbered operands The template section contains plain assembler and uses ordinary ST200 assembler syntax with the notable exception of the i i is a positive integer notation that refers to the it output operand or input operand Multiple consecutive strings are automatically concatenated and enable a readable and correct template input Multiple assembler instructions can be put together in a single asm template separated by explicit newline characters Nn If there are no output operands but there are input operands two consecutive colons
110. executable or shared library can reference it directly STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Attributes 115 Note 6 3 4 protected Protected visibility indicates that the symbol will be placed in the dynamic symbol table but that references within the defining module will bind the local symbol This means that the symbol cannot be overridden by another module internal Internal visibility is like hidden visibility but with additional processor specific semantics For the ST200 this means that the function is never called from another module That hidden symbols though they cannot be referenced directly by other modules can be referenced indirectly by function pointers By indicating that a symbol cannot be called from outside the module the compiler may for instance omit the load of a PIC register since it is known that the calling function has already defined the correct value Miscellaneous attributes format The format attribute specifies that a function takes printf scanf strftime or strfmon style arguments which should be type checked against a format string extern int my printf void my object const char my format __attribute_ format printf 2 3 format_arg The format_arg attribute specifies that a function takes a format string for a printf scanf strftime or strfmon style function and modifies it so that the result can be passed to a pr
111. fine extended_isoc99_eprintf format fprintf stdout extended_isoc99_eprintf format VAARGS define errprintf args gnu_eprintf errprintf s n args int main int argc char argv Try 1 2 3 arguments gnu_eprintf One argument s Done n FILE gnu_eprintf Two arguments s d Done n FILE LINE isoc99 eprintf One argument s Done n FILE isoc99 eprintf Two arguments s d Done Ain FILE LINE extended isoc99 eprintf One argument s Done n FILE extended isoc99 eprintf Two arguments s d Done n FILE LINE extended isoc99 eprintf Three arguments s s d Done in _ FUNCTION FILE LINE e STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Extensions to the C language family 105 The case with no arguments gnu_eprintf No arguments Done in The line below causes a syntax error isoc99 eprintf No arguments Done n extended_isoc99 eprintf No arguments Done n Cascade of macros with variable number of arguments errprintf FILE return 0 6 2 14 Strings literals with embedded newlines GNU cpp permits string literals to cross multiple lines without escaping the embedded newlines Each embedded newline is replaced with a single newline character in the resulting string literal regardless of what form the newline took originally The macro
112. he end of the current function e pragma noinline function foo prevents inlining of function foo every time it is called until the end of the current function The two call site scope pragmas take precedence over these two function scope pragmas Two lower priority pragma are provided with file scope e pragma inline file foo to force inlining of function foo every time it is called until the end of the current source file e pragma noinline file foo to prevent inlining of function foo every time it is called until the end of the current file Finally to revert inlining policy to the default one that is rely on the inliner s evaluation of callee weight the following pragma is introduced pragma defaultinline foo 5 2 4 3 Function naming As a special case if the user does not provide any function name the corresponding pragma applies to all functions called in the scope of the pragma In this case parentheses around the function names are optional 5 2 4 4 User diagnostics Several warning messages are provided to the user to help track errors If two conflicting pragmas are provided only the later is taken into account For instance pragma inline next foo pragma noinline next foo foo leads to warning pragma noinline next foo overrides previous pragma inline next foo hy ST Microelectronics ST200 Micro Toolset User Manual ADCS 7508723H Inlining 5 2 4 5 5
113. ibility specification 91 Internal visibility has no remaining overheads To support visibility declarations the current st200cc compiler implements e visibility attribute GNU extension e linker option Bsymbolic which has the same effect as protected visibility but at link time only e linker version scripts that allow the user to explicitly list the symbol that is required to be exported globally thus reducing the dynamic symbol table size The following sections give example usage of the fvisibility and mvisibility decl options 5 10 2 Usage of the fvisibility option This option is mainly used to declare by default all symbols as having hidden visibility The advantage of this is that the user has to declare by using attributes the functions or data that he explicitly wants to be global For instance if the interface for a library is reduced to three functions initialize process and finalize the user can enable better code generation by including the config h file see Figure 7 in its sources and using the fvisibility hidden option at compile time define VISIBILITY v _ attribute_ visibility v extern void initialize void VISIBILITY protected extern void process void VISIBILITY protected extern void finalize void VISIBILITY protected Figure 7 config h 1 The_ attribute _ visibility GNU extension does not apply to static symbols as ELF defines visibility only for globa
114. ied regular expression suitable for globbing as generally found in shell command line expansion The implementation uses the globbing function fnmatch of the libiberty a GNU library The LANGUAGE is one of C or C and specifies the demangling scheme that must be used to match a symbol If no language declaration is specified the pattern must match the assembly name of the symbol For example Figure 9 is a commented visibility specification file dummy v A sample visibility protected will match the my_func will match the my data will match all protected 7 default extern C will match all std will match all typeinfo std will match all vtable std will match all VTT std hidden extern C will match all mycomplex specification file symbol named my_func symbol named my_data symbols prefixed by protected_ C symbols of std namespace typeinfo information of std namespace vtable of std namespace vtable tables of std namespace methods data of the mycomplex class will match the vtable for complex using the mangled name _ZTV9mycomplex Figure 11 dummy v gr STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 96 Symbol visibility specification 7 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H y Y PRELIMINARY DATA O GNU Cexte
115. implicit int 14 Windows 3 Wlong long 15 Wmissing braces 14 Wmissing declarations 15 Wmissing noreturns 15 Wmissing prototypes 15 17 Wnested externs 15 Wno deprecated 37 Wpacked 15 Wpadded 15 Wparentheses 14 STMicroelectronics ADCS 7508723H PRELIMINARY DATA Wpointer arith 14 Wredundant decls 15 Wreturn type 14 Wshadow 14 Wsign compare 15 Wstrict prototypes 15 Wswitch 14 Wtrigraph 14 Wunknown pragmas 14 Wunused 14 Wwrite strings 15 XYZ XVCG dump 170 Y lt phase gt lt path gt 23 STMicroelectronics 205 I ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 206 7 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H
116. ing new intrinsics int st200mul32 int int int _ st200mul64h int int unsigned int _ st200mul64hu unsigned int unsigned int int _ st200mulfrac int int These intrinsics were originally developed to give quick access to new ST231 instructions when they were not selected by the compiler However the three integer multiplication intrinsics are now almost useless since the compiler correctly selects the new instruction The last intrinsic __st200mulfrac is never selected by the compiler since its semantic is complex multiply fractional with saturation and rounding To simplify development work these intrinsics are available for any ST200 core They are expanded e asa single machine instruction when the target is st231 for example when mcore st231 command line is used e as a sequence of instructions that emulate the behavior of the st231 native instructions for other cores st220 Table 56 summarizes these intrinsics properties either when emulated or native Instructions critical Name path for emulation ST220 Instructions critical path for ST231 __st200mu132 __st200mul64h st200mul64hu 13 6 1 1 __st200mulfrac 17 8 1 1 Table 56 ST231 intrinsics properties I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 146 Division and modulus built ins 8 7 Division and modulus built ins The compiler supports sev
117. int This pragma allows the user to specify information about the execution frequency for certain regions of code with the following frequency specifications NEVER This region of code is never or rarely executed The compiler might move this region of the code away from the normal path This movement might either be at the end of the procedure or at some point to an entirely separate section FREQUENT This region of code is frequently executed The compiler might try to put this region in the fall through path Example if debug pragma frequency hint NEVER trace 9j STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 58 4 3 4 3 1 4 3 2 7 PRELIMINARY DATA Miscellaneous pragmas Miscellaneous pragmas pragma ident Adds a comment section in an assembly file pragma weak Marks a symbol as weak Instructs the link editor to not issue a warning if it does not find a defining declaration of the specified weak symbol In which case the symbol is set to 0 Allow the overriding of the current definition by a non weak definition pragma weak opt_handler extern void opt handler void int main int argc char argv If opt _ handler has not been defined the linker does not complain and the condition is false If opt handler has been defined the opt_handler is invoked if opt_handler opt_handler STMicroelectronics ST200 Micro Toolset User Manu
118. int64 DSP operator _ mazi _ uint64 max uint64 _uint64 DSP operator _ maxul int64 min int64_int64 DSP operator minl __uint64 min uint64_uint64 DSP operator _ minul int32_clamp_int64 DSP operator __clamplw ID sat int32 round int64 DSP operator _ roundlw ID round int32 roundc int64 DSP operator __ roundclw ID round __int32 near int64 IEEE operator __nearlw int32 nearc_int64 IEEE operator nearclw __fract64_mulc_fract32_fract32 DSP operator __mpfewl D_mult __fract64_ mul fract32_fractl6 DSP operator _ mpfml __int64_puth_int32 DSP operator puthl __ int64 _putl _int32 DSP operator putll __int32_geth_int64 DSP operator __gethw ID ertract __int32 getl int64 DSP operator getlw D_extract_h Table 53 High precision fractional arithmetic ky STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 144 Intrinsic functions summary Intrinsic Purpose ST200 Name uint16 swapb uint16 DSP operator swapbh __uint32_swaph_uint32 DSP operator __swaphw uint32_swapb_uint32 DSP operator __swapbw Table 54 Bit and byte ordering Intrinsic Purpose ST200 Name __uint16_bitent_uint32 DSP operator __bitcentw uint16_bitcnt_uint16 DSP operator __bitenth Table 55 Population count 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA ST231 intrinsics 145 8 6 ST231 intrinsics This compiler supports the follow
119. intf scanf strftime or str mon style function extern char my dgettextprintf void my domaint const char my format _ attribute format_arg 2 mode This attribute specifies the data type for the declaration whichever type corresponds to the mode Refer to the GNU Compiler Collection Internals document for the definitions of modes see http gcc enu org onlinedocs gccint I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 116 Attributes Use the keywords byte word and pointer _ toindicate the mode corresponding to these quantities unsigned int qi _ attribute mode QI unsigned int w _ attribute_ mode word 6 3 5 Built ins A built in is used as a function call but is expanded by the compiler very early in the intermediate representation instead of doing a function call builtin_constant_p This built in tests if a value is a constant at compile time int x define C 1 int main if builtin constant p C 1 printf c is proved to be a constant n if builtin constant p x 0 printf x is a not proved to be a constant n return 0 builtin_return_address __builtin_return_address gets the return address of the currently executing function void bar printf RA 0x 08x n int builtin return address 0 builtin_expect long _ builtin expect long exp long c _ builtin expect provides the compiler
120. ion This chapter describes the different categories of compiler bugs and how they should be reported to STMicroelectronics 9 2 Identifying a compiler bug 9 2 1 Category 1 The following cases are compiler or toolset bugs e the compilation phase ends with an assertion message e the compilation phase ends with a system error message core dump bus error e the compilation phase produces an output that cannot be assembled e the compilation phase never ends or at least does not end in a reasonable amount of time e the compiler produces an error message for code that is valid input e the compiler produces code that does not compute the expected results but see Section 9 2 2 gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 148 PRELIMINARY DATA Checks performed by user 9 2 2 Category 2 The following case is possibly not a compiler or toolset bug The code is functional under a specific optimization level but not under another This may be due to an existing code bug that is only exposed by aggressive optimization 9 3 Checks performed by user The following checks should be performed on your code before reporting a bug check that the code works correctly on at least one other compiler on another host check that the code does not access out of bound memory check that the source code does not raise any warning when compiled with the Wal1 option check that the source code does
121. ion never overlap Table 28 Possible value to the OPT alias option Although the compiler is able to compute precise memory dependences in many cases this is not possible when complex memory accesses are involved such as in the following example for i 1 i lt n i a i 1 a i b il for i 1 i lt n i cldlill c i 1 _ _ __ iy ST Microelectronics ADCS 7508723H ST200 Micro Toolset User Manual 70 57 PRELIMINARY DATA Memory dependences in C programs On the first loop the compiler can fully determine the dependences between memory accesses provided that it knows that a and b point to distinct memory locations see the C language restrict qualifier On the second loop however without information on values in d the compiler assumes that all memory accesses in the loop are dependent In particular the sequence of load and store memory accesses in the iterations of the loop must be strictly respected resulting in a poor instruction schedule if the loop is unrolled or software pipelined A useful property for loop optimizations is when a loop is vectorizable This property can be enforced on a loop by using the pragma loopdep VECTOR A vectorizable loop is such that it can be decomposed into a sequence of loops one per statement of the original loop without changing the program results Moreover for each loop resulting from that decomposition that contains onl
122. iples However the generated relocation graph takes into account all symbols data read only data and code This graph is traversed and un reached nodes are removed Candidate symbols to these optimizations must e have the moveable assembler attribute procedures beginning with proc and ending with endp automatically have the moveable attribute data needs the moveable attribute to be set with the following syntax type my data object moveable The compiler generates this attribute for symbols that it estimates to be moveable This generation is not linked to any optimization level e have a size e be assembled with emit all relocs option to st200as This option is set by st200cc driver if dead code or ICache optimizations are required Such a symbol is called a moveable symbol in the rest of this section These conditions guarantee that all relocations within a moveable symbol are not resolved and that all relocations pointing towards a moveable symbol are also not resolved So such a symbol can be safely removed or moved Relocations will be resolved in a final link by st2001d Note 1 ICache optimization and dead code removal are implicitly turned on by the st200cc hy Os and 02 and higher optimization options 2 Debug information is preserved by binary optimizations 3 Mixing objects files compiled at different optimization levels is safe Only symbols with the listed characteristics are ca
123. is implies that all C code must be compiled using the fno exceptions option Be aware that even if your code does not use exceptions the standard headers do so you must use fno exceptions Note The STL generally relies on exceptions In the absence of exception implementation the run time support simply calls abortQ when an exception is encountered For instance a failure to allocate memory through the new operator goes through a throw_bad_alloc function that in turns calls abort when the exception support is disabled The usual stack unwinding process is not activated so the objects that would be destroyed automatically through this process are not It is not possible to write exception specifications in function prototypes when the exception support is disabled except for the empty specification clause throw It is possible to have a more explicit abort diagnostic by establishing a signal handler on the SIGABRT signal The compiler defines the preprocessor macro __EXCEPTIONS only when exceptions are enabled When writing code to work both with and without exception handling support use this macro to select the appropriate statements 3 10 Checking operator new return value When operator new is overloaded with a definition that may return 0 it must be declared throw or the user must use the fcheck new compiler option otherwise unexpected control flow will be generated Consider the following example where
124. isters The syntax for a register descriptor is register_type cluster register_number where e the register type is a string usually one character that defines the bank of registers within a cluster e the cluster equals 0 e the register number denotes the register within that bank Example r0 1 general purpose register 1 of cluster 0 b0 3 branch register 3 of cluster 0 c0 add r0 3 r0 3 42 r0 3 lt r0 3 42 c0 add r0 11 r0 12 1 r0 11 lt r0 12 1 ee oe In the preceding example two adds are scheduled to be issued in a single cycle As can be seen the cluster identifiers are redundant I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 184 Assembler syntax In the currently planned ST200 processors c0 has the following register banks r A bank of 64 general purpose 32 bit registers b A bank of 8 single bit branch or condition The branch registers are used as condition bits for branch and select operations as well as operations that generate or consume carry bits There are a few general purpose registers with defined functions r0 0 These registers always return 0 when read r0 63 This register known as the link register is used to store the return address for all call operations In addition it is read for the target address by some call and goto operations To simplify the ST200 assembly syntax starting from the R3 2 release of the t
125. ity Profiling feedback optimization PFO Principles The st200cc profiling feedback model is a three step process Instrumentation of C C sources Execution of the binary on sample input generating files of feedback data The run can be executed either on a simulator or on hardware Feedback annotation of C C at the same point as in the first compilation Sources are enhanced with feedback data that are used and refined during the compilation process st200cc feedback instruments the input sources early in the compiler back end Consequently feedback annotations are almost independent from optimization levels Command line The st200cc command line option fb create lt name gt is used to generate an instrumented executable program This can be used to produce one or more name instr0 files for subsequent feedback compilation gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 84 Profiling feedback optimization PFO When the c option is used to produce an object file that is eventually linked to form an instrumented executable the b create option should also be specified at link time If different names are specified the one used to compile the main file where the main procedure is will be used The executable is instrumented with special instructions that generate information that the compiler can use to better optimize your program When this instrumented ex
126. iven to lines that begin with followed by an absolute expression In this case the expression is interpreted as the logical line number of the next line An optional string following such an expression is interpreted as a new logical file name The rest of the line if any should be whitespace 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Assembler syntax 177 Example This is an ordinary comment 42 6 new file name New logical file name This is logical line 36 Comments beginning with the strings APP or NO APP also have a special interpretation and should not be used 11 2 3 Lexical categories 11 2 3 1 Whitespace Whitespace consists of one or more blanks or tabs in any order Unless whitespace occurs within character constants any whitespace sequence is treated as exactly one space 11 2 3 2 Symbols A symbol is one or more characters chosen from the set of all letters both upper and lower case digits and the four characters _ No symbol may begin with a digit Case is significant All characters are significant Symbols are delimited by characters not in the set described above or by the beginning of a file since the source program must end with a newline the end of a file is not a possible symbol delimiter 11 2 3 3 Constants A constant is a number written so that its value is known by inspection without knowing any context Example byte 74
127. keyword that requires the std c99 command line option to be specified It is recommended that any code fragment that depends upon C99 specific behavior be guarded by the following preprocessing definitions which are correctly triggered when the std c99 command line option is used Hif defined __STDC VERSION amp amp __STDC VERSION gt 1999011 Your C99 dependent code here else error This source file depends upon C99 features not available with this compiler endif Table 15 summarizes the status of the st200cc compiler C99 support Feature as described in the C99 standard Status Restricted character set support via digraphs NO include file not provided lt iso646 h gt Wide character library support NO type not supported and library not provided More precise aliasing rules via effective type YES provided that the fstrict aliasing Option is used Restricted pointer YES Variable length arrays PARTIAL only local allocation but no other features Flexible array members NO Static and type qualifiers in parameter array declarators NO Complex support lt complex h gt NO Type generic math macros lt tgmath h gt NO include file not provided Table 15 C99 support in st200cc Ij STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 28 57 PRELIMINARY DATA Feature as described in the C99 standard The long long int type and library functions Inc
128. l symbols This is unfortunate as the compiler can take advantage of the fact that a static function is internal Though the extensions allow static symbols to be declared internal gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 92 Note 57 PRELIMINARY DATA Symbol visibility specification This informs the compiler that all functions or data defined for the compilation of the library are hidden except those explicitly declared protected in the config h file Without the fvisibility option the user would have to attribute all of the functions definition with the VISIBILITY hidden macro The fvisibility hidden option has some limitations It applies only to function definitions not to declarations Thus ifa file that is part of the library references a symbol in another file in the same library the compiler still generates GOT accesses as it does not have the information that the definition is effectively in the library To remove the above limitation the user must use the ipa option that enables the compiler to consider all files at once and thus effectively apply the code generation optimizations 5 10 3 Usage of the mvisibility decl option The main usage of the mvisibility decl option is to avoid modifying the source code by adding explicit visibility attributes to function and data declarations and definitions For instance this effect with the fvisibility hidden option can be achiev
129. le 4 29 2 15 5 enum vl 1 v2 2 v4 4 int b 6 1 v1 v2 4 v4 struct point int x y struct point makep int xvalue int yvalue struct point p y yvalue x xvalue return p struct point makepp int xvalue int yvalue struct point p y yvalue x xvalue return p With GNU C the character can be omitted after the index indication 6 2 20 Case ranges Case ranges may be specified with integer value intervals in switch statements const char which int v switch v case 0 31 return Control case A Z return Upper case a z return Lower default return None 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Extensions to the C language family 109 6 2 21 Cast to a union type A cast to union type is similar to other casts except that the type specified is a union type The type is specified either with the union tag or with a typedef name union foo int i double d u v makefoo int i double f u union foo i v union foo f 6 2 22 Dollar signs in identifier names Dollar signs are allowed in identifier names int Sa 6 2 23 Prototypes and old style function definitions GNU C extends ISO C to allow a function prototype to override a later old style non prototype definition int isroot uid_t int isroot x lossage here
130. lectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 186 Assembler syntax call r63 r63 call through the link register goto dest_label goto a destination return r63 same as goto S r63 Only one branch goto or call operation may be issued in a single bundle Furthermore the bundle sequentially following a taken branch goto or call operation is quashed 11 2 8 4 Memory operations The ST200 processors support three basic categories of memory operations loads stores and prefetches In the current processors a bundle may include at most one memory operation Memory addressing The ST200 architecture only supports one addressing mode All memory accesses are made via a pointer in a register plus an immediate offset The assembler syntax for this is offset register Example stw 4 r1 123 Sr1 4 lt Sr23 Dismissible modifiers The ST200 processors support speculative dismissible load operations In particular it is possible to provide code that dereferences a pointer prior to the test to determine that the pointer is valid A memory operation may be defined by software to be dismissible in the event that a non recoverable virtual memory fault occurs by performing a dismissible load the value returned is defined to be 0 A dismissible load is denoted by the operation modifier d In the following example probe a evaluates to true if a can legally be dereferenced E
131. led from outside this generates a specific sequence in the prologue of the function A pointer to the symbol function or data is taken from the GOT entry generating a load instead of a single address computation and some additional data for the GOT entry Inlining of the function symbol is not possible as the symbol is preemptible A call to the function symbol goes through a stub function in the PLT generating one additional jump to the stub function and some additional code for the stub function The symbol appears in the dynamic Yes Yes No No symbol table this augments the size of the loadable data segment Table 30 Visibility overheads a This overhead can be removed by some link time options and by the use of linker version scripts These link time options are not used by the compiler to optimize the code b Inlining of the function symbol is possible as the symbol is not preemptible c A pointer to the symbol can be built from a GP relative address computation as the symbol is local to the library d A call to the function symbol is direct as the symbol is local to the library e The symbol does not appear in the dynamic symbol table as it is local to the library f There is no need to set up the GP value as the function was called from another function inside the same library and thus the GP value is already set STMicroelectronics ADCS 7508723H PRELIMINARY DATA Symbol vis
132. libgec a libraries libgloss a libgprof a libc a libm a 9j STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA lt tools dir gt lib engine lt core target gt lt endianess gt lt tools dir gt include lt tools dir gt target lt tools dir gt target board lt board target gt lt core target gt lt endianess gt lt run time gt See Section 2 2 19 on page 22 lt tools dir gt man 1 4 1 Example command lines adaptor rcu basicsim dll st200emu dl1l gdiserv exe gdiserv dll stmrpc dll st200sim dll lt all the include files gt targets cfg bootboard o libboard a lt man pages gt ST200 Micro Toolset interface execution engines the target tree containing all of the BSP files relative to the core board and soc see the ST200 Cross Development Manual for more information file containing all the known targets of the toolset used by st200gdb and st200run the boot code and board specific code for target board_target The ST200 Micro Toolset produces an ST200 object file in ST200 object file formats elf Assuming that we want to compile two files file1 c and file2 c into an ST220 little endian executable a e1f the set of commands to issue is 1 st200cc c filel c 2 st200cc c file2 c 3 st200cc o a elf filel o file2 o This assumes that the PATH environment variable has been updated with lt tools dir gt bin
133. lt type are identical int 32 type therefore the suffix wis used 3 Therefore the generic model name of the operator is __maxw All operators have been quite thoroughly defined to avoid redundancies and are limited to useful combinations There is no need for example to have a fractional addition operator because addition of fractional types using the same representation is equivalent to addition on ordinary integral types gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 130 8 3 8 3 1 Note Note Note hi PRELIMINARY DATA Using intrinsics from C C Using intrinsics from C C Include files This section explains the usage of include files that are peculiar to intrinsics All techniques described here apply to both C and C and the headers are both C and C compatible Using intrinsics on an ST200 platform ST200 intrinsics prototypes are available in the st220 h include file All header files mentioned in this chapter apply to both the ST220 and ST231 To include intrinsics in an application use include lt st220 h gt If ETSI names are required use the following as well include lt etsitost220 h gt This injects a set of macros that renames original ETSI ITU basic operators Most of these macros are just name defines with the exception of shift operators that are macros with parameters This means that it is not possible to take the address of shift operators Inc
134. luding st220 h implicitly includes st220types h which defines the appropriate basic types Using intrinsics models Prototypes for the intrinsic models are provided in imodels h and their implementation is in imodels c To include an intrinsics model in an application use include lt imodels h gt If ETSI names are required use the following as well include lt etsitom h gt STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Using intrinsics from C C 131 Note Note 1 Including imodels h implicitly includes st220types h which defines the appropriate basic types Care must also be taken to link with the imodels o file produced on the specific platform Switching between ST200 intrinsics and modelled intrinsics Is is often extremely useful to be able to keep the same source baseline either running with models on a workstation or on an ST200 platform For example on an ST220 this is done using the implicitly defined __st220__ symbol Hifdef _ st220__ include lt st220 h gt include lt etsitost220 h gt else 1_ st220__ include lt imodels h gt include lt etsitom h gt endif _ st220__ It is possible to remap names in both directions For an ST231 platform the symbol __st231__ would be used with the same ST220 header files as these apply equally to ST231 An application written exclusively using the model names can be retargeted immediately to ST20
135. ly file If the symbol is external then the value stored in the object file is the last value assigned to it global symbol This directive defines a symbol as external that is visible to the linker A label can also be marked as global directly by defining it with a double colon 11 2 9 5 Include directive include file This directive provides a way to include supporting files at specified points in your source program The code from file is assembled as if it followed the point of the include when the end of the included file is reached assembly of the original file continues gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 190 Assembler syntax 11 2 9 6 ST200 machine directives assume parameters The assume directive expects one or more parameters separated by commas It is also possible to use several consecutive assume directives The parameters of the assume directive are encoded in the elf flags of the object file to identify the basic code generation assumptions taken by the compiler This allows the linker to detect attempts to link code assembled with different incompatible assumptions The assume directive is generated by the C compiler The user should only consider writing a assume directive when mixing assembly code with C code The assume directive accepts five types of parameters listed in Table 59 Values within the parameter types
136. lysis Optimization STMicroelectronics ADCS 7508723H PRELIMINARY DATA ST200 Micro Toolset interface 5 14 ST200 Micro Toolset interface The interface to the toolset is a command line interface and makes the assumption that a command line shell like sh ksh csh tesh or similar is available to the user On Windows XP 2000 systems this is provided by the CYGWIN32 system see http sources redhat com cygwin for details Most of the ST200 tools work as command line interfaces with the exception of the debugger st200gdb that is optionally available with a Tel Tk interface The steps involved in getting from a C program to an ST200 executable image are hidden from the user and implemented by the st200ce driver The ST200 Micro Toolset supports the ST220 and ST231 cores both little endian and big endian code generation and both bare machine and OS21 run time environments It is installed in a directory tree with the structure shown below The example shows part of a Windows directory tree lt tools dir gt bin st200ar exe archiver st200as exe assembler st200cc exe C compiler driver st200c exe C compiler driver st200gdb exe debugger st2001d exe linker st200run exe driver for simulator or hardware lt other binary utilities gt lt tools dir gt lib cmplrs lt all the compiler components gt lt tools dir gt lib lt core_target gt crtxxx o C runtime start up files lt endianess gt lt run time gt
137. m gt lt iomanip gt lt bits gt lt ios gt lt bitset gt lt iosfwd gt lt cassert gt lt iostream gt lt cctype gt lt istream gt lt cerrno gt lt iterator gt lt cfloat gt lt limits gt lt ciso646 gt lt list gt lt climits gt lt locale gt lt clocale gt lt map gt lt cmath gt lt memory gt lt complex gt lt new gt lt csetjmp gt lt numeric gt lt csignal gt lt ostream gt lt cstdarg gt lt queue gt lt cstddef gt lt set gt lt cstdio gt lt sstream gt Table 22 STL standard header files STMicroelectronics ADCS 7508723H PRELIMINARY DATA Standard Template Libraries STL support 41 Header files lt cstdlib gt lt stack gt lt cstring gt lt stdexcept gt lt ctime gt lt streambuf gt lt cwchar gt lt string gt lt cwctype gt lt typeinfo gt lt deque gt lt utility gt lt exception gt lt valarray gt lt fstream gt lt vector gt lt functional gt Table 22 STL standard header files 3 7 2 Supported extension headers All these extensions live in the __gnu_cxx namespace compared with the stg namespace of the standard library functions Note Using these extensions can be useful however it may restrict portability because not all compilers or libraries support these extensions Header files lt ext algorithm gt lt ext memory gt lt ext functional gt lt ext numeric gt lt ext hash_map gt lt ext rope gt lt
138. ment memory spatial locality or cache line spatial locality may be enforced Profile based optimization dynamic mode is performed by first running the application collecting profiling data and then recompiling and linking the application passing in the profiling data to the ICache optimizer Static analysis is performed by the optimizer using estimation instead of run time data The binopt phase also performs dead code and unused data removal st200cc provides a set of options to customize this phase Binary optimizations are performed in several phases and it is important to pass the optimization options to both the compilation and the link phase Several examples are given in Section 10 3 on page 163 I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 152 PRELIMINARY DATA Introduction 10 1 1 How it works Note Binary optimizations are based on studying relocation at the assembler level The ICache optimizer builds a call graph estimated or not according to the mode used The edges are weighted by the number of calls between procedures This weight is estimated from compiler information contained in the profile info section Then some algorithms stemming from the references are applied and an optimal function layout is found see Section 10 6 References on page 174 Only functions whose body is in the text section are candidates to move Dead code and dead data elimination follow the same princ
139. mory accesses that are either in the same or different loop iterations This pragma is equivalent to pragma ivdep OPT liberal_ivdep TRUE Example pragma loopdep liberal for i 0 i lt n i alji b il c il ali 3 In this example the compiler cannot tell that the load ofa i does not depend on the store of a j This is in fact the case if i j for all values of i and j in the loop iterations STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Loop optimization pragmas 53 4 2 4 pragma loopmod Note This pragma tells the compiler the number of times a loop is taken in terms of a multiple q and a residual r The syntax of this pragma is pragma loopmod q r where qis strictly a positive integer ris a positive integer r lt q For example pragma loopmod 4 0 This tells the compiler that the loop is taken 4 8 12 times pragma loopmod 4 1 This tells the compiler that the loop is taken 5 9 18 times When applied to an inner loop this pragma indicates that the trip count tc that is the number of iterations that are executed by any execution of the loop can be written as te pq rwithp gt 0 r gt 0 Where p is strictly a positive integer This information helps the compiler in loop unrolling optimization and in software pipelining When unrolling loops the compiler creates multiple loop bodies the unrolling factor specifies the n
140. must be placed where the output operands would go gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 120 Introduction In the output and input list e each operand is described by an operand constraint string followed by a C expression in parentheses e the available constraints are the following x general purpose register operand b boolean register operand iimmediate integer operand including symbolic constants only known at assembly time nimmediate integer operand known at compile time g general purpose register or immediate integer e an operand constraint can be prefixed by the following modifiers write only operand used for output operands early clobber operand does not prevent the use of In the clobber list e general registers are referred to by ri where i has the range 10 631 they map to the corresponding Ri hardware registers e branch registers are referred to by bi where i has the range 0 7 they map to the corresponding Bi hardware boolean registers 7 1 2 Assumptions e Output operand expressions must be 1values e The compiler assumes that the input is consumed before the outputs are produced unless an output operand has the amp constraint modifier also called early clobber The compiler will not assign the same register to an input operand and an early clobber operand However the compiler may assign the s
141. n elimination This option removes subprograms which are never called from the program The default is on IPA dve ON OFF Enables or disables dead variable elimination This option removes variables which are never referenced from the program The default is ON IPA forcedepth n Sets inline depths Instead of the default inlining heuristics this option directs IPA to attempt to inline all functions at a depth of at most n in the call graph where functions which make no call are at depth 0 those which call only depth O function are at depth 1 and so on This ignores the default heuristic limits on inlining IPA inline 0N OFF Performs inter file subprogram inlining during main IPA processing The default in ON IPA keeplight 0N OFF Directs IPA to not send keep to the compiler in order to save space The default is on Setting it to OFF will leave intermediate files in a directory which has the name of the final executable suffixed with ipakeep Table 29 Advanced IPA options I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 88 Interprocedural analysis optimization IPA Description IPA maxdepth n Directs IPA to not attempt to inline functions at a depth of more than nin the call graph where functions which make no call are at depth 0 those which call only depth O functions are at depth 1 and so on Inlining remains subject to overriding limits on code exp
142. n this example the compiler cannot tell when a i k does not depend on a i but this is in fact the case if kis always gt 0 in the program The pragma allows the compiler to assume there are no dependences between the read of a i k in the current loop iteration and the write of a i in the following loop iterations The compiler could rewrite the loop as for i 0 i lt n it 2 to ali k1 3 t1 a i 1 k 3 a i t0 a i 1 t1 9j STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 52 hy PRELIMINARY DATA Loop optimization pragmas pragma loopdep PARALLEL pragma loopdep PARALLEL allows the compiler to assume there are no dependences between any two memory accesses that are in different loop iterations This pragma is equivalent to pragma ivdep OPT cray_ivdep FALSE OPT liberal_ivdep FALSE Example pragma loopdep PARALLEL for i 0 i lt n itt a b i a b i 3 In this example the compiler cannot tell that either the load or store of a b i in the current loop iteration does not depend on the load or store of a b i ina following loop iteration This is in fact the case ifb i b j foralli j The compiler could rewrite the loop as for i 0 i lt n it 2 t1 a b i 1 3 to a b i 3 a b i 1 t1 a b i t0 pragma loopdep LIBERAL pragma loopdep LIBERAL allows the compiler to assume there are no dependences between any two me
143. nator must reside on a separate line in the source file each operation is treated as a separate statement The bundle may be interleaved with comments Each operation of a bundle is a separate syntactic statement Example operation0 a comment operationl another comment operation2 ee rr Labels may not appear within a bundle they must occur before the first operation of the bundle The destination of a branch must be the start of a bundle The ST200 processors are implemented with a single cluster called co The assembler uses the operand syntax to determine the target cluster for a particular operation however as an aid to readability a cluster identifier may optionally precede each operation of a bundle These identifiers have the form cx where xis a cluster number STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Assembler syntax 183 Example c0 operation0 operationl ee rr The assembler does not interpret the cluster identifiers they are purely an aid to reading complex code In order to determine where a syllable is scheduled and hence to generate the bits corresponding to a bundle the assembler uses cluster information embedded in register names The syntax for operands is discussed in Section 11 2 7 11 2 7 Operands 11 2 7 1 There are two basic types of operands used in defining the ST200 operations register identifiers and immediates Reg
144. ndidates for binary optimization STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Introduction 153 10 1 2 Synopsis Several options specifically relate to ICache optimization and may be used in conjunction with the icache opt option they are summarized below and described in detail in Section 10 2 on page 156 Enable or disable ICache optimization st200cc icache opt on off Enable ICache optimization using a user defined ordering file to order functions in the final executable st200cc icache opt on icache mapping file ly Apply compiler generated static analysis to the optimization st200cc icache opt on icache static icache algo algorithm Apply profiling data obtained during program execution to the optimization st200cc icache opt on icache profile file dt icache profile exe exe dt icache algo algorithm Enable dead code and data removal st200cc deadcode Disable dead code and data removal st200cc no deadcode iy STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 154 PRELIMINARY DATA Introduction 10 1 3 ICache files Table 58 provides a synopsis of each of the files used in binopt optimization at File Description Simulator trace file This gives start and destination addresses for each jump in the execution sequence Use the TracePlugin simulator plug in This has the extension so for Unix host
145. ned 2 s complement 32 bit integer Some expression operators may only be applied to absolute sub expressions 11 2 5 3 Operators e Prefix operators The assembler supports the following unary prefix operators The argument must be absolute Negation Two s complement negation Complement Bitwise not e Infix operators The assembler provides a number of binary infix operators Apart from or both arguments to the operator must be absolute the result is absolute Within a precedence class operators are applied left to right Highest precedence Multiplication Division truncation is the same as the C operator P Remainder lt Relational less LI STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 182 PRELIMINARY DATA Assembler syntax lt lt Shift left same as the C operator lt lt gt Relational greater gt gt Shift right same as the C operator gt gt Intermediate precedence Bitwise inclusive OR amp Bitwise AND A Bitwise exclusive OR Bitwise NOT Lowest precedence Addition Subtraction 11 2 6 Bundles 57 An ST200 processor may issue multiple conventional instructions operations in a single cycle these operations are statically scheduled A group of simultaneously issued operations is called a bundle The end of a bundle is denoted by Each operation of a bundle as well as the bundle termi
146. ned in the library If this assertion if violated a static link time error will occur 2 Only the symbols initialize process finalize are accessible to the other modules There will be a dynamic link time error if this assertion is violated by another module 3 All other symbols are local to the library The advantage of 1 is that the library dependencies on other modules are explicit It can be useful for libraries though in some contexts it may be time consuming to enumerate all such symbols The advantage of 2 is that the library interface is explicit and an error occurs if it is violated Lia STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 94 Note 1 Se A bo PRELIMINARY DATA Symbol visibility specification The advantage of 3 is that the compiler can optimize all these hidden symbols and optimize all the references to these hidden symbols The ipa option is not necessary in this case to optimize reference to symbols as opposed to the Evisibility hidden option The ipa option is still useful to further optimize the library by identifying from the set of hidden symbols which ones are internal A sufficient condition for a symbol to be internal is that it is hidden and the address is never taken The ipa option can compute the address taken property and use the fact that the symbol has been declared hidden to set it internal The visibility specification file can be used to specify int
147. ng the STL version Note 3 8 The version supported is defined numerically through __GLIBCPP__andasastring through GLIBCPP VERSION With the current release the value of__GLIBCPP__ is 20040214 and the value of_GLIBCPP_VERSIONis 3 3 3 These versions are consistent with the C front end used A simple way to show it is to compile and run the following program include lt cstdio gt int main int argc char argv lt printf _ GLIBCPP__ is d __GLIBCPP_ VERSION is s n __GLIBCPP _GLIBCPP VERSION return 0 In future releases this preprocessor definition might be deprecated and replaced by __GLIBCXX__ and _GLIBCXX_VERSION RTTI notes The rtti support is enabled by default to disable it use the fno rtti compiler option When rtti is enabled there is e support for the lt typeinfo gt header and the typeid operator e support for dynamic cast If rtti is disabled e the compiler refuses to compile code containing calls to the typeid operator e code containing calls to dynamic cast has undefined behavior and typically aborts at run time The limitation is that as exceptions are not supported the exception std bad_cast is never thrown in case dynamic cast fails this is replaced by a call to the abort library function I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 44 Exceptions notes 3 9 Exceptions notes Exceptions are not supported Th
148. ng with M or MM treat missing files as generated in the local directory H Display the name and path of the header in use dM Print a list of macros definitions in use after preprocessing Use with the E option dD Print a list of macro definitions in use while preprocessing Use with the E option dN Same as 4D except that the macro arguments are not shown Use with the E option fpreprocessed Indicate to the preprocessor that the input file has already been preprocessed Table 4 Preprocessor options 7 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Command line options 13 2 2 4 C dialect options The option std value instructs the compiler front end to select the appropriate C language dialect to use For instance the C99 restrict keyword is only recognized with the std c99 option However this keyword also exists as a GNU extension keyword either _ restrict or__restrict__ that are recognized by default Possible values for std are listed in Table 5 Option Description std iso9899 1990 Same as ansi std is09899 199409 ISO C as modified in amendment 1 std is09899 1999 ISO C 99 std c89 Same as std is09899 1990 std c99 Same as std is09899 1999 std gnu89 This is the default iso9899 1990 gnu extensions std gnu99 iso9899 1999 gnu extensions Table 5 C Dialect options 2 2 5 Warning options Diagnostic messages c
149. nlined If any instances of the function remain they will refer to the single copy in the library Inlining pragmas Introduction The inlining process can be controlled within the C source code using pragmas The st200cc compiler already supports several command line options to configure its behavior but it is not flexible enough For instance with the option INLINE never foo the user can disable the inlining of foo everywhere it is called conversely with INLINE must foo the user can force inlining of foo everywhere The user has the ability to force inlining or non inlining at call sites through the use of pragmas In addition the noinline and always_inline attributes can be used at function declaration Pragmas To force inlining or non inlining of a function in the scope of a call site the following two pragmas are introduced e pragma inline next foo forces inlining of function foo in the next statement e pragma noinline next foo prevents inlining of function foo in the next statement The denotes that it is possible to provide several function names with the same pragma It is equivalent to several pragma lines I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 64 Inlining Two similar pragmas are provided that can be used within the scope of a function e pragma inline function foo forces inlining of function foo every time it is called until t
150. nsions supported by st200cc 6 1 Introduction GNU cc provides a large set of extensions that are widely used in the GNU Linux community These extensions can be used to e describe embedded features for example data section placement e provide guidance to the compiler for optimization for example the noreturn function e provide language extensions for example conditional lvalue or C99 features e instruct the compiler to modify the Application Binary Interface for example using the packed attribute The GNU extensions are sometimes the only way to access ELF features that are not directly available in the C language for example to declare a symbol weak I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 98 Extensions to the C language family 6 2 Extensions to the C language family st200cc provides several language features not found in ANSI standard C The pedantic option directs st200cc to print a warning message if any of these features are used To test for the availability of these features in conditional compilation check for a predefined macro __GNUC__ which is always defined under st200cc It is recommended to always put code containing st200cc extensions under the C pre processor macro __GNUC_ if GNUC Original GNU code else Work around code endif 6 2 1 Statements and declarations in expressions Statements and declarations in expr
151. nts into section name data Assemble the following statements into the data section text Assemble the following statements into the text section Ir STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 188 Assembler syntax 11 2 9 3 Data directives comm symbol length alignment Declare a named common section in the bss section The 1ength and alignment parameters must be absolute expressions Skip size fill Fill the next size bytes with the optional i11 value The default case is to fill with 0 byte expression number datal expression number These directives which are equivalent take one or more pairs of parameters separated by commas The first value of the first expression is assembled into the next byte location The second optional parameter indicates the number of duplicate bytes to generate Any expression that evaluates to a value that cannot be represented by a byte is truncated with a warning hword expression number data2 expression number These directives which are equivalent take one or more pairs of parameters separated by commas They assemble the value of the first expression into the next two bytes If the expression evaluates to a value that requires more than 16 bits to represent it then it is truncated and a warning issued The second parameter in each pair is optional if present it specifies the number of consecutive 16 bit locations
152. o understand In order to understand the precise operating semantics it helps to understand the model implementation that intrinsics are based on The following sections describe the fundamental operators that the models are based on then gives an implementation example Understanding fundamentals operators The following macro operators are defined e EXT x n normalizes x considered signed on n bits in a long long e EXTU x n normalizes x considered unsigned on n bits in a long long e CLAMP x n saturates xon n bits in a long long All models are based on a systematic and consistent use of the operators which enables understanding of the inner workings of intrinsics I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 134 PRELIMINARY DATA Intrinsic functions summary 8 4 2 Understanding models 8 5 hy Consider the example of the __int16_addc_int16_int16 operator int16 int16_addc_int16_int16 int16 r0 int16 r1 long long t0 EXT r0 16 long long t1 EXT r1 16 long long t2 t0 t1 long long t3 CLAMP t2 16 return t3 In this example inputs are normalized to long long through the EXT operations keeping 16 bits signed precision Then the addition is computed with full precision and finally the result is saturated to 16 bits by the CLAMP operator Intrinsic functions summary The tables shown in Section 8 5 1 provide the names of all ST200 intrinsics functions along
153. of aliasing rules if a 0 0 puts LEGACY BEHAVIOUR else puts STRICT ALIASING BEHAVIOUR return 0 Figure 2 Aliasing example source The aliasing rules were designed to allow compilers to perform more aggressive optimization Basically a compiler can assume that all changes to variables happen through pointers or references to variables of a type compatible to the accessed variable De referencing a pointer that violates the aliasing rules results in undefined behavior In the case above the compiler may assume that no access through an integer pointer can change the float a Thus the actual value of a may be unaffected by the writing through pa What really happens is up to the compiler and may change with architecture and optimization level To disable optimizations based on alias analysis for faulty legacy code the option fno strict aliasing must be used as a work around Because the practice of reading from a different union member other than the one most recently written to called type punning is common even with fstrict aliasing type punning is allowed provided the memory is accessed through the union type So to fix the code above you can use a union instead of a cast as shown in Figure 3 on page 73 This is a GCC extension which might not work with other compilers STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Aliasing rules in C C prog
154. on 5 10 2 Usage of the fvisibility option 5 10 3 Usage of the mvisibility decl option 5 10 4 The visibility specification file 6 GNU C extensions supported by st200cc 6 1 6 2 ADCS 7508723H Introduction Extensions to the C language family 6 2 1 Statements and declarations in expressions 6 2 2 Locally declared labels 6 2 3 Labels as values 6 2 4 Naming an expression s type 6 2 5 Referring to a type with typeof 6 2 6 Generalized L values 6 2 7 Conditionals with omitted operands 6 2 8 Double word integers 6 2 9 Hexadecimal floats 6 2 10 Specifying a register for a local variable 6 2 11 Array of length zero 6 2 12 Array of variable length 6 2 13 Macro with variable number of arguments 6 2 14 Strings literals with embedded newlines 6 2 15 Non Lvalue arrays may have subscripts 6 2 16 Arithmetic on void and function pointers 6 2 17 Non constant initializers 6 2 18 Compound literals 6 2 19 Designated initializers 6 2 20 Case ranges 6 2 21 Cast to a union type 6 2 22 Dollar signs in identifier names 6 2 23 Prototypes and old style function definitions 6 2 24 C comments 6 2 25 Character ESC in constants STMicroelectronics vii 89 91 92 94 97 97 98 98 99 99 100 100 100 101 101 101 101 102 103 104 105 106 106 107 107 108 108 109 109 109 109 110 Ka ST200 Micro Toolset User Manual PRELIMINARY DATA viii 6 2 26 Inquiring on alignment of types or variables 110 6 2 27
155. oolchain the cluster number is no longer required in the register syntax By default the cluster 0 will be used by the assembler The two following instructions are then equivalent add r11 r12 r2 add r0 11 r0 12 r0 2 11 2 7 2 Immediates There are two basic types of immediates absolute and PC relative In the ST200 family PC relative immediates are used for branch call and goto operations while all other immediates are absolute All immediates are encoded as 2 s complement numbers Immediates that can be represented with a small number of bits are encoded directly in the machine word containing the operation while longer immediates require an extension word The ST200 assembler allows all immediates to be defined by a number symbol or expression In the case of PC relative immediates defined by labels the assembler calculates the value relative to the PC 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Assembler syntax 185 11 2 8 Operations There are two basic types of operation statements accepted by the assembler integer operations and control flow operations such as branches The syntax of each class of operation is described in detail below Case is significant in operation names all operation names are lower case 11 2 8 1 Integer operations As a general rule operands that are written by an operation appear to the left of any while operands
156. oops In order to generate a prefetch for a memory reference the compiler may need to generate the prefetch on an earlier iteration of the loop to the memory reference To calculate the address that is used in the later iteration the compiler requires the difference between the load address and the prefetch address to be an integer constant For example given the following code for i 0 i lt 10 i load array i STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Data prefetching 77 In Figure 6 on the i iteration we want to load array i and eight iterations later we will want to load array i 8 To speed up the load of array i 8 the compiler prefetches array i 8 while it loads array i This is possible because array i 8 is a known constant distance from array i array i 8 ithyg iteration load i 8 k i it iteration load i prefetch i 8 i 8 i k where k is a constant Figure 6 Pre fetching on earlier iteration of loop The resulting compiled code has the prefetch instruction added for i 0 i lt 10 i load array i prefetch array i 8 The compiler can handle more complex cases than this but in all cases the distance between the load address and the prefetch address distance k in Figure 6 must be a known constant 1 Mathematically the load address must be a linear function of the enclosing loop iteration vari
157. operator new is declared throw include lt cstdio gt namespace Tspace class T public void operator new size t n return 0 3 T ctor static int ctor int T ctor 0 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Checking operator new return value 45 void surprise puts UNEXPECTED n int main int argc char argv using namespace Tspace T p new T if p 0 surprise else if T ctor 0 puts FAILURE else puts SUCCESS Using this example the following command st200c example cxx outputs the warning warning operator new must not return NULL unless it is declared output throw or fcheck new is in effect output Running the executable st220run tsim a out produces the following message FAILURE Compiling the example with the fcheck new option and running the resulting executable st200c fcheck new example cxx st220run tsim a out produces the message SUCCESS Lia STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 46 Known limitations 3 11 Known limitations 3 11 1 Status of the known limitations The known limitations are e no exception support e performance pragmas are not recognized e no intrinsics support 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H y Y PREL
158. orced on a loop by using the pragma loopdep LIBERAL A liberal loop is one where all its memory accesses reference unique memory locations As a result all the memory accesses in the loop can be freely reordered Note that a liberal loop is always parallelizable so the pragma loopdep LIBERAL is stronger but less generally applicable than the pragma loopdep PARALLEL STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Aliasing rules in C C programs 71 Note In the example above the second loop is liberal if the assertion ril lt 1 dlil gt n holds for all i For clarity we omitted this case for the VECTOR and PARALLEL pragmas The restrict qualifier which applies to pointers or arrays in a C program is also highly useful to remove dependences between memory accesses inside and outside loops The restrict property states that two memory accesses originating from different pointers or arrays cannot reference the same memory location when at least one of the pointers or array has the restrict qualifier Please note that all memory accesses based on a given restrict pointer or array are still assumed dependent unless it is obvious to the compiler that they are not or there is a pragma loopdep on the loop that applies to these dependences Aliasing rules in C C programs The fstrict aliasing option allows the compiler to assume the strictest aliasing rules applicable to the language
159. otboard o libboard a and board x located in target board lt board_target gt lt core_target gt lt endianess gt lt runtime gt are linked mcore lt core_target gt Selects the core_target code generation mode in the compiler Available targets are st220 and st231 bootcore o libcore a and core x located in target core lt core_target gt lt endianess gt lt runtime gt are linked msoc lt soc_target gt Select a SOC target bootsoc o libsoc a and soc x located in target soc lt soc_target gt lt core_target gt lt endianess gt lt runtime gt are linked Table 12 Configuration options 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H Command line options PRELIMINARY DATA 23 2 2 20 Directory and library options Table 13 lists the options that select header files libraries and compiler executables Option Description Idirectory Add directory to the beginning of the search list for include files nostdinc No predefined include search path 1 lt library gt Search the library named lib lt library gt a when linking The linker looks for the library in the directories specified by the L options and then in a standard list of directories The position of this option on the command line makes a difference The linker processes object files and libraries in the order that they are specified on the command line For example if the following is specified st2
160. out Trace options davinci y lt file gt Dump call graph into davinci syntax See daVinci V2 1 dump on page 170 dump d Dump call graph to stdout in xvcg format See VCG XVCG dump on page 170 icgdump D Dump Cache call graph user configuration help h Displays a help page of options version V Show version verbose v Increase verbose level by one default is 0 Type of optimization coloring C Change the placement algorithm to coloring algorithm COL ltrg L Change the placement algorithm to Large Temporal Relationship Graph LTRG only applicable in profiling mode and may be very long ph P Change the placement algorithm to Pettis amp Hansen PH90 default algorithm ph_col 0 Change the placement algorithm to a mix of PH90 and coloring PH_COL Use PH90 call graph merge with COL node merge Node merge attempts to minimize cache conflicts using the set of the available colors for each procedure profile X Perform dynamic optimization from a profile file default mode yr STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H binopt PRELIMINARY DATA trg T static S call graph configuration 169 Change the placement algorithm to Temporal Relationship Graph TRG only applicable in profiling mode Perform static optimization from profile_info section contents begin b lt proc weight gt ignore
161. p to see an example of such a file It can be useful to add edges which are not caught by a simple relocation analysis indirect call or syscalls or to remove polluting calls which you know are not taken This option is only valid for static mode e ignore lt proc gt all calls to proc and its descendants are ignored It may be useful to ignore calls to a library procedure This option may be used in both static and profile mode For example ignore printf ignore fprintf e begin lt proc weight gt any procedure specified with this option is interpreted as an entry point in your application Relative weight can be specified to give more importance to one procedure in relation to another This option can be used in both static and profile mode In profile mode weight is ignored For example begin myapp_init 0 3 begin myapp main 0 5 begin myapp_finish 0 2 or in profile mode begin myapp init begin myapp_main begin myapp finish gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 172 PRELIMINARY DATA Warning and error messages 10 4 5 User command file A command file containing options to pass to binopt is specified by using the lt filename gt option Options can be separated by space tabulation or newline For example cat cmd binopt gt begin init 0 2 begin main 0 8 gt ignore printf gt ignore fprintf gt davinci myapp davinci binopt layoutfile mye
162. pe Warn when a comparison between signed and unsigned values could produce an incorrect result Warn if any functions that return structures or unions are defined or called Warn if a function is declared or defined without specifying the argument types Warn if a global function is defined without a previous prototype declaration Warn if a global function is defined without a previous declaration Warn about functions which might be candidates for attribute noreturn Warn if anything is declared more than once in the same scope 5 Wnested externs Warn if an extern declaration is encountered within a function Wlong long Warn if Long long type is used Only active along with pedantic Wpacked Warn if a structure is given the packed attribute but the packed attribute has no effect on the layout or size of the structure Wpadded Warn if padding is included in a structure either to align an element of the structure or to align the whole structure ADCS 7508723H Table 7 Detailed warning options iy STMicroelectronics ST200 Micro Toolset User Manual 16 2 2 6 Note 2 2 7 Note 2 2 8 2 2 9 Note 57 PRELIMINARY DATA Command line options Debugging options The g option instructs st200cc to generate symbolic information for debugging DWARF 2 format is used The g option may be used with optimization up to level 02 and with Os see Section 2 2 9
163. put object file relocatable object output Output object file relocatable object input_exe Input executable real executable for dynamic ICache optimization deadcodeobject lt file gt Keep intermediary output object file after dead code elimination layoutfile lt file gt Keep intermediary output layout file of functions 1y file deadcodefile lt file gt Keep intermediary list of removed symbols preserved lt name gt Preserve a symbol and all its descendants More than one preserved option may be given Only one name may be given with each preserved option section_ preserved lt my_section gt Preserve all symbols defined in my_section and all its descendants More than one section_preserved option may be given Only one name may be given with each section_preserved option scan_end_proc E Use old endproc label to find function size default is false function size is now deduced from elf attributes User command file lt file gt Give a user command file See Section 10 4 5 User command file on page 172 ky ST Microelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 168 binopt Input and output options icg g lt file gt ICache call graph user configuration user defined edges See Section 10 4 4 How to configure binopt on page 171 outlayout o lt file gt Specify file where layout is written if omitted output is sent to std
164. r Form BNF Briefly 1 Terminal strings of the language that is those not built up by rules of the language are printed in teletype font For example void 2 Nonterminal strings of the language that is those built up by rules of the language are printed in italic teletype font For example name 3 Ifa nonterminal string of the language starts with a non italicized part it is equivalent to the same non terminal string without that non italicized part For example vspace name 4 Each phrase definition is built up using a double colon and an equals sign to separate the two sides 5 Alternatives are separated by vertical bars 6 Optional sequences are enclosed in square brackets and Items which may be repeated appear in braces and Ka STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA xvi 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H 1571 ST200 development PRELIMINARY DATA system 1 1 ST200 compiler overview The purpose of the st200cc compilation driver is to translate a program written in the C language into the ST220 assembly language so that is suitable for assembly linking and execution The assembler file is compiled using st200as and linked using st20014 to provide an ST200 binary image All these phases are hidden using the driver tool st200cc The st200cc compiler uses the
165. ract16_fract16 ETSI mod_s __modfch Table 44 Modulus intrinsics Intrinsic Purpose ST200 name int64_mul_int32_int16 C optimization __mpml uint64_mul_uint32_uint16 C optimization _ mpuml __fract32_mulc_fract16_fract16 ETSI L_mult __mpfcw __fract16_mulrc_fract16_fract16 ETSI mult_r __mpfrch Table 45 Multiply special intrinsics hy STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA ADCS 7508723H STMicroelectronics Intrinsic functions summary 139 Intrinsic Purpose ST200 name int32 mulh int32 int32 C Runtime __mulhw Arithmetic helper int16_mulh int16_int16 C Runtime __mulhh Arithmetic helper uint32_mulh_ uint32_uint32 C Runtime __mulhuw Arithmetic helper uint16 mulh uint16_uint16 C Runtime _ mulhuh Arithmetic helper Table 46 Multiply high intrinsics Intrinsic Purpose ST200 name uint32_edges_uint32_uint32 DSP operator __edgesw uint16_edges_uint16_uint16 DSP operator __edgesh __uint32_rotl1_uint32_uint16 DSP operator __rotlw _ uint16_rotl uint16 uint16 DSP operator __rotlh __uint32_xshl_uint32_uint32_uint16 DSP operator __xshlw uint16_xshl_uint16_uint16_uint16 DSP operator __xshlh uint32_xshr_uint32_uint32_uint16 DSP operator __xshrw __uint16_xshr_uint16_uint16_uint16 DSP operator __xshrh uint16_xshr_uint16_uint16_uint16 DSP operator priorl int16_prior_int32 DSP oper
166. ractional modulus _bitent_ Population count _bitrev_ Bit reverse _rotl_ Rotate left _xshl_ Cross shift left _xshr_ Cross shift right _edges_ Edges _lzcnt_ Leading zero count _prior_ Get left shifts to normalize _norm_ ETSI get left shifts to normalize _clamp_ Saturation _round_ Rounding _get_ Get high low part _put_ Put in high low part _bitclr_ Bit clear _bitset_ Bit set _bitnot_ Bit complement _bitval_ Bit test Table 32 ST200 intrinsic operator names hy STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Naming intrinsics 129 Note Model Ae Description Remarks stem _inseq_ Compare for equal and insert _insne_ Compare for not equal and insert _insgt_ Compare for greater and insert _insge_ Compare for greater or equal and insert _inlts_ Compare for less and insert _insle_ Compare for less or equal and insert Table 32 ST200 intrinsic operator names For example searching for an operator that computes the maximum value of two 32 bit integers is quite simple 1 Operator stem is max and there is no specific ST200 name 2 Operands are both of int32 type so the suffix is int32_int32 3 Result type is int32 so the prefix is int32 4 Therefore the generic model name of the operator is int32_max_int32_int32 To get the specific ST200 operator name is also quite simple 1 Operator stem is max there is no specific ST200 name 2 Operand and resu
167. rams 73 include lt stdio h gt According to GNU documentation this code should work in both strict and non strict aliasing rules int main int argc Char argv union float f int i u u f 0 0f u i 0x40000000 is 2 0 if u f 2 0 puts NON GNU BEHAVIOUR else puts GNU ALIASING BEHAVIOUR return 0 Figure 3 Aliasing example using a union Now the result is always GNU ALIASING BEHAVIOUR Finally to fully respect the ANSI C C aliasing rules it is necessary to write the data through a character type before reading it again see Figure 4 on page 74 and Figure 5 on page 75 iy ST Microelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 74 Aliasing rules in C C programs The drawback of this standard conforming solution is that it has to account for endianness and that it is less efficient than simply writing through an integer include lt stdio h gt According to ANSI standard this code should work in both strict and non strict aliasing rules include lt stdio h gt define EXTRACTBYTE val pos val gt gt pos 8 amp Oxff int main int argc char argv union float f char c 4 u const unsigned int twoasint 0x40000000 u f 0 0f if defined _ BIG ENDIAN u c 0 EKTRACTBYTE twoasint 3 u c 1 EXTRACTBYTE twoasint 2 u c 2 EXTRACTBYTE twoasint 1
168. ration YES lf conversion allowed in printf NO Inline functions YES but not fully ansi compliant in the extern inline case The snprintf family of functions in lt stdio h gt NO library support not provided Boolean type in lt stdbool h gt NO bool native type but lt stdbool h gt header provided Idempotent type qualifiers YES but still emits warnings Empty macro arguments YES New struct type compatibility rules NO Additional predefined macro names MOST _Pragma preprocessing operator YES Standard pragmas NO __func__ predefined identifier YES VA_COPY macro NO Additional strftime conversion specifiers NO library support not provided LIA compatibility annex NO Deprecate ungetc at the beginning of a binary file NO Remove deprecation of aliased array parameters NO Table 15 C99 support in st200cc gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 30 C99 support 7 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H 1971 st200c 3 1 Note 3 1 1 PRELIMINARY DATA Introduction to st200c The toolset features a GNU C 3 3 3 front end with full library support but no exceptions support It is therefore recommended that you always compile with the fno exceptions option The current known limitations are documented they will be removed in future releases This C compiler aims at improving performance and compliance with indu
169. reased minimum translation unit Additional floating point characteristics lt float h gt C99 support Status YES but C libraries may not provide full support YES NO Remove implicit int NO but can get warning Reliable integer division YES Universal character names NO Extended identifiers NO Hexadecimal floating point constants YES but no a A printf scanf scanf conversion specifiers Compound literals YES Designated initializers YES comments YES Extended integer type and library functions in lt inttypes h gt and lt stdint h gt NO include file not provided Remove implicit function declaration NO can get warning Preprocessor arithmetic done in intmax_t uintmax_t YES Mixed declaration and code NO New block scope for selection and iteration statements NO Integer constant type rules NO Integer promotion rules NO vararg macro YES The vscan family of function in lt stdio h gt and lt wchar h gt NO library support not provided Additional math library functions in lt math h gt NO Floating point environment access in lt fenv h gt NO Table 15 C99 support in st200cc STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA C99 support 29 Feature as described in the C99 standard Status ISO 60559 Arithmetic support NO Trailing comma allowed in enum decla
170. rently defined can be obtained by typing st200c E dM filename cxx where filename cxx can be any cxx file including an empty file 3 Do not rely on a macro that is not documented even if it is currently defined 4 Some macros values are subject to change in future compiler versions for instance front end identification values Name Default definition Purpose See also _ GNUC__ 3 Front end major no gcc release identification GNUC_MINOR 3 Front end minor no gcc release identification __GNUC_PATCHLEVEL__ 3 Front end minor no gcc release identification Table 21 Predefined macros 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H Predefined macros PRELIMINARY DATA Default definition Purpose C Front end major release identification 37 See also no gcc _LANGUAGE_C_PLUS_PLUS Defined only for C source Language currently processed is C language _ cplusplus Defined for C source Language currently processed is C language STRICT_ANSI Defined when std c 98 ansi Compiler is in strict ansi mode std Wno deprecated is used __ EXCEPTIONS Defined unless Compiler f no Jexceptions fno exceptions supports is used exceptions _ DEPRECATED defined unless Compiler Wno deprecated supports legacy code GKK ABI VERSION 102 C abi version Note
171. right of the sign as in INLINE list a11 It is generally recommended to use ON TRUE 21 for the sake of clarity for example INLINE list 0N inline Enable inlining on inline functions This is activated by default at optimization levels gt 1 noinline Disable inlining INLINE on off Enable disable inlining Use of other INLINE options implicitly set this to on INLINE all Bypass cost evaluation when inlining may inline functions This option conflicts with none and takes precedence if both are specified Default is off INLINE all_inline Inline all functions marked by the C language inline keyword Table 26 Standalone inlining options Lia STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 62 Inlining INLINE only_inline on off Default is on Inline only functions marked by the C language inline keyword The INLINE only_inline off option is mandatory to allow inlining of non inline functions INLINE static on off Default is off Allow static functions to be candidates for inlining INLINE aggressive on off Inline even non leaf out of loop calls Default is off INLINE list on off List compiler actions Default is off INLINE must namel name2 Always attempt to inline the names subroutines in addition to the default heuristic INLINE never name1 name2 Never attempt to inline the names subroutines
172. rinsic Purpose ST200 name int64 mul _int32_int32 C optimization _ muln uint64 mul uint32_uint32 C optimization mulun int32 mul _int32 int16 C optimization _ mulm int16_mul_int16_int16 C optimization __mulh __uint32_ mul uint32 uint16 C optimization _ mulum _ uint16_mul_uint16_uint16 C optimization _ muluh fract32_mulc_fract32_fract32 DSP operator _ mulfcw _ fract32_mulc_fract32_fract16 DSP operator __mulfcm __fract16_mulc_fract16_fract16 ETSI mult __mulfch Table 42 Multiply intrinsics I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 138 Intrinsic functions summary Intrinsic Purpose ST200 name int32 div int32 int16 C optimization divm int16 div int16 int16 C optimization divh uint32 div uint32 uint16 C optimization _ divum _ uint16 div uint16 uint16 C optimization divuh __fract32_dive_fract32_fract32 DSP operator divfcw __fract32_dive_fract32_fract16 DSP operator __divfcm __fract16_dive_fract16_fract16 ETSI div_s __divfch Table 43 Divide intrinsics Intrinsic Purpose ST200 name int32 mod _int32 int16 C optimization _ modm int16_mod_int16_int16 C optimization __modh uint32_mod_uint32_uint16 C optimization __modum __uint16_mod_uint16_uint16 C optimization __moduh __fract32_modc_fract32_fract32 DSP operator __modfcw __fract32_modc_fract32_fract16 DSP operator __modfcm __fract16_modc_f
173. rn type that defaults to int Wswitch Warn whenever a switch statement may be incomplete Wtrigraph Warn if any trigraphs are encountered that might change the meaning of the program Wunused Warn whenever a static function a label a parameter a value is not used Wunknown pragmas Warn when a pragma is encountered which is not understood by st200cc Wmultichar Warn if a multi character constant is used Wshadow Warn whenever a local variable shadows another variable Wpointer arith Warn about anything that depends on the size of a function type or of void Wbad function cast Warn whenever a function call is cast to a non matching type Table 7 Detailed warning options 57 ST200 Micro Toolset User Manual STMicroelectronics ADCS 7508723H Command line options Option Wcast qual Wcast align Wwrite strings Wconversion Wsign compare Waggregate return Wstrict prototypes Wmissing prototypes Wmissing declarations Wmissing noreturn Wredundant decls PRELIMINARY DATA 1 Description Warn whenever a pointer is cast so as to remove a type qualifier from the target type Warn whenever a pointer is cast such that the required alignment of the target is increased Warn when trying to write to a string constant Warn if a prototype causes a type conversion that is different from what would happen in the absence of a prototy
174. s The compilation time and the link time is longer as much of the optimization work is driven from the linker This can be observed by using the v compiler option The following steps are performed when building an executable in IPA mode e the c files are translated into special o files e the o files are merged together code symbol table e the o files are analyzed and optimized e the final link is performed 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Interprocedural analysis optimization IPA 87 5 9 3 IPA command line options The following table describes advanced IPA options Option Description IPA aggr_cprop ON OFF Enables or disables aggressive inter procedural constant propagation Attempts to avoid passing constant parameters replacing the corresponding formal parameters by the constant values The default in ON IPA cgi ON OFF Enables or disables constant global variable identification This options marks non scalar global variables which are never modified as constant and propagates their constant values to all files The default is ON IPA cprop ON OFF Enables or disables inter procedural constant propagation This option identifies formal parameters which always have a specific constant value The default is ON See also IPA aggr_cprop IPA depth n This option is identical to maxdepth n IPA dfe ON OFF Enables or disables dead functio
175. s 10 2 4 Full optimization 10 2 5 Relocatable files 10 2 6 Shared libraries call shared executable 10 2 7 Passing other options to the optimization phase Examples 10 3 1 Compiling with static ICache optimizations STMicroelectronics 134 135 145 146 147 147 147 147 148 148 148 149 149 151 151 152 153 154 156 160 160 161 161 161 162 162 163 163 gj ST200 Micro Toolset User Manual x 10 3 2 optimizations 10 3 3 To keep a generated layout file 10 3 4 Using profile driven ICache optimizations 10 3 5 higher 10 3 6 165 10 3 7 Linker options 10 4 binopt 10 4 1 Synopsis 10 42 Options 10 4 3 binopt dump options 10 4 4 How to configure binopt 10 4 5 User command file 10 5 Warning and error messages 10 5 1 binopt 10 6 References 11 Assembler 11 1 Introduction 11 2 Assembler syntax 11 2 1 General description 11 2 2 Comments 11 2 3 Lexical categories 11 2 4 Symbols 11 2 5 Expressions 11 2 6 Bundles 11 2 7 Operands 11 2 8 Operations 11 2 9 Assembler directives 11 38 Invoking the assembler hy PRELIMINARY DATA Compiling a relocatable object with static ICache 164 164 164 Using profile driven ICache optimizations using O2 or 165 Compiling with st200gprof file driven ICache optimizations STMicroelectronics ST200 Micro Toolset User Manual 166 166 166 167 170 171 172 172 172 174 175 175 176 176 176 177 179 181 182 183 185 187 192 ADCS 75087
176. s ST200 Micro Toolset User Manual PRELIMINARY DATA 196 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H y Y PRELIMINARY DATA Index Symbols characters 109 comment character 176 __alignof_ 110 args 104 _asm_ 119 pragma 111 __attribute__ 39 defaultinline 48 64 __BARE_BOARD _ 26 frequency_hint 47 57 _ BIG_ENDIAN__ 25 indent 48 58 _ builtin__divuw 146 inline file 48 64 builtin_ divw 146 inline function 48 64 inline next 48 68 __builtin__moduw 146 ivdep 47 50 __builtin__modw 146 loopdep 47 51 52 __builtin__prefetch 75 loopmod 47 53 __builtin_classify_type 117 loopseq 47 56 __builtin_constant_p 39 116 looptrip 47 54 __builtin_expect 39 116 noinline file 48 64 noinline function 48 64 noinline_ next 48 63 __builtin_prefetch 79 117 builtin_return_address 116 pipeline 47 55 byte__ 116 unroll 47 49 _ cplusplus 26 37 weak 48 58 _ DEPRECATED 37 character 109 _ EXCEPTIONS 37 44 PATH 6 133 _func 29 amp unary operator 106 _ FUNCTION 110 amp amp unary operator 99 _ GLIBCPP__ 43 comment 58 _ GLIBCXX__ 43 and comment characters 176 _ gnu cxx 41 I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 198 GNUC 24 36 98 _ GNUC_MINOR__ 24 36 _ GNUC_PATCHLEVEL__ 36 __GNUG_ 37 __GXX_ABI_VERSION 37 __INLINE_INTRINSICS 26 _ LITTLE ENDIAN_ 25 _ Open64_ 24 _ OPTIMIZE__ 26 __05821 BOARD 26 __pointer__
177. s which can then be applied to various primitive types or user defined data types Without this extension it is necessary to define as many specific macros as the number of different types used in calls to the generic macro define max a b TA typeof a _a a typeof b _b b a gt _b _a _b Generalized L values Compound expressions conditional expressions and casts are allowed as lvalues provided their operands are 1values For example a b 5 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Extensions to the C language family 101 6 2 7 6 2 8 6 2 9 Conditionals with omitted operands The middle operand in a conditional expression may be omitted for example zZz X y Double word integers long long support integer 64 bits is supported by the ST200 Micro Toolset It is now also an ISO C99 feature long long x Hexadecimal floats Floating point numbers are written in hexadecimal format float f 0x1 fp3 6 2 10 Specifying a register for a local variable A register may be specified for a local variable for example register long r15 asm r15 name 9j STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 102 Extensions to the C language family 6 2 11 Array of length zero Zero length arrays are allowed in GNU C They are very useful as the last element of a structure
178. s C language _LANGUAGE_ASSEMBLY Defined for ASM Language source currently processed is assembly language STRICT_ANSI Defined when Compiler is in std std c89 or strict ansi mode std c99 or ansi Table 14 Predefined macros Si ADCS 7508723H STMicroelectronics ST200 Micro Toolset User Manual 26 Default definition PRELIMINARY DATA Purpose Predefined macros See also optimization is on STDC VERSION Defined when Compiler is in std std c99 with C99 ansi mode value 199901L _ OPTIMIZE Defined as soon as Optimization 0 mode detection INLINE_INTRINSICS Defined Intrinsics inlining mode detection OPT inline _ intrinsics STDC_HOSTED Defined by default Hosting mode no hosted no freestanding BARE BOARD Defined by default Run time support mruntime identification 0S21 BOARD Defined when Run time support mruntime os21 mrunt ime os21 identification Table 14 Predefined macros Note That the C standard guarantees that the _ cplusplus symbol is never defined when compiling C source code 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA C99 support 27 24 C99 support The st200cc compiler supports a subset of the C99 standard Most features are implicitly available through default compiler command line options with the notable exception of the restrict
179. s are given in Chapter 10 ICache dead code optimization 2 2 17 Specifying the run time environment The mruntime name option selects the run time environment for the compilation and link name may be either bare to select a bare machine or os21 to select the 0821 run time libraries The default is a bare machine gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 22 Command line options To select a run time other than the default the mruntime option must be used for both the compilation and link The OS21 for ST200 User Manual describes the use of OS21 for ST200 cores 2 2 18 Selecting the endianness The EL option selects code generation for a little endian core and propagates this option to all the tools that are invoked by the compiler The startup and libraries are also selected based on this information to be little endian This is the default The EB option selects the big endian mode for compiler code generation startup and libraries selection 2 2 19 Configuration options Options are provided which enable system configuration parameters called sysconf parameters or a boot code file to be selected at link time These options and the modules they select to be linked are described in more detail in the Getting started chapter of the ST200 Cross Development Manual they are listed in Table 12 Option Description mboard lt board_target gt Select a board target bo
180. s or d11 for Windows Hosts This file is passed to st200cc via the icache profile option ly Function layout file This gives the order of functions in the final executable This file is generated by the st200cc icache static or icache profile options when the keep option of st200cc is used or hand written and passed to st200cc with the icache mapping option po Pre optimized object file This file is a relocatable object file and is generated with the r linker option It contains unresolved relocations A relocatable object file is used by the reordering phase in order to move code relocations must not be resolved This file is kept when the keep option of st200cc is used Op 7 Post optimized object file This file is a relocatable object It contains reordered code The final executable is obtained by resolving relocations in this file simple link phase This file is kept when the keep option of st200cc is used Table 58 st200cc binopt optimization files STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H Introduction PRELIMINARY DATA 155 Description Instruction cache call graph file This file is a user external file Use this to add edges to the estimated static call graph see Section 10 4 4 How to configure binopt on page 171 for more details rmlist Removed symbol file This file is generated by binopt when dead code
181. s types are almost the same the aliasing rules are stated in the ANSI C standard in clause 6 5 7 Expressions For example an unsigned int can alias an int but nota void ora double A character type may alias any other type The default is fno strict aliasing for legacy reasons In future releases the fstrict aliasing option will be used by default no unroll loops funroll loops forces loop unrolling This is the default at 02 and 03 Loops are unrolled up to 4 times at 02 and up to 8 times at 03 with a limit on code size expansion Loops with a pragma unrol1 directive are not affected by this option fno unroll loops disable loop unrolling This is the default at Os Loops with a pragma unrol1 directive are not affected by this option Table 9 Advanced Optimization options 2 2 10 Code generation options The options in Table 10 control various aspects of the code generation Option Description The feedback file to use for feedback instrumentation See Section 5 8 Profiling feedback optimization PFO on page 83 fb lt name gt Generate an executable with feedback instrumentation See Section 5 8 Profiling feedback optimization PFO on page 83 fb_create lt name gt Table 10 Code generation options I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 18 Option fsigned char funsigned char fsigned bitfiel
182. scription of the expected result and the actual result e Report all the above information through your local ST Field Applications Engineer FAE Finally when in doubt it is preferable that a possible bug is reported than forgotten 9 6 Known bugs and limitations Please refer to the Bug list supplied with the toolset on the CD for an up to date list of bugs and limitations I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 150 Known bugs and limitations 7 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H y Y PRELIMINARY DATA O ICache dead code optimization 10 1 Introduction st200cc includes a binary phase optimization This phase calls the binopt binary that performs ICache optimization dead code and data removal st200cc provides a comprehensive set of options to perform ICache optimization These options call the binopt binary which may also be invoked directly as described in Section 10 4 binopt on page 166 The ICache optimization options of the st200cc driver control the final function layout of the program Function reordering in the final executable is important for targets with instruction cache Indeed functions that have temporal locality determined by static analysis or profile based analysis should also have spatial locality in order to optimize cache usage by reducing cache conflicts Depending on the algorithm used for function place
183. ser Manual ADCS 7508723H PRELIMINARY DATA Attributes 111 6 3 6 3 1 Attributes Generally attributes are a much better design than a pragma directive for a number of reasons Firstly an attribute specification is a piece of C language that can be generated by use of a cpp macro definition whereas a pragma directive generation is generally not supported by non GNU C preprocessors Secondly it avoids the scoping issues of the pragma directive Several attributes can be applied to the same object by using a comma to separate them For example to declare a symbol that is both weak and aliased void useful void _ attribute weak alias useful_func Placement and layout section Applied to function Place a function in a user defined section void myfunc void _ attribute _ section mytext void myfunc void printf From myfunc in mytext section n Applied to a data object Place the data in a user defined section struct duart a _attribute__ section DUART_A 0 Support must be explicitly added in the startup file or system loader to load the newly created section aligned Applied to a variable or a structure field Specifies a minimum alignment for a variable or structure field measured in bytes The aligned attribute can only increase the alignment it can be decreased by specifying packed as well int x __attribute_ aligned 16 0 struct _s int x 2 _ attribute
184. sis between memory accesses The pragma ivdep applies only to inner loops If it is used on a loop that has an inner loop the compiler ignores it By default this pragma allows the compiler to assume there are no memory dependences between loop iterations The following command line options modify the ivdep semantic e OPT cray_ivdep TRUE Only ignore backward memory dependences Cray semantics e OPT liberal_ivdep TRUE Also ignore all memory dependences in the same loop iteration STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Loop optimization pragmas 51 4 2 3 Ezample pragma ivdep for i 0 i lt n i a b i alb i 3 These dependences cannot be computed by the compiler pragma loopdep This pragma instructs the compiler to liberalize dependence analysis between memory accesses based on the specified type of loop dependences Contrary to the pragma ivdep described above the semantics cannot be modified by command line options The loopdep pragma takes an argument to tell the compiler which kind of loop dependencies it can ignore VECTOR PARALLEL or LIBERAL pragma loopdep VECTOR pragma loopdep VECTOR allows the compiler to assume there are no backward memory dependences between loop iterations This pragma is equivalent to pragma ivdep OPT cray ivdep TRUE Example Hpragma loopdep VECTOR for i 0 i lt n i a i a itk 3 I
185. strial standards ISO IEC 14882 Common Vendor ABI SYSV ELF Using the st200c compiler is very similar to using st200cc therefore only the new options definitions and usage rules are documented in this chapter References The ISO IEC 14882 1998 C standard is available from your local ISO or ANSI outlet A useful source of information concerning the C standard is http www open std org JTC1 SC22 WG21 The GNU Compiler documentation can be found at http gcc enu org The Common vendor ABI is described at http www codesourcery com cxx abi gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 32 3 2 3 2 1 3 2 2 57 PRELIMINARY DATA Getting started Getting started The st200c compiler is similar to any command line compiler It is either invoked from a command line interpreter or from a Makefile and implicitly recognizes files by their extension It recognizes all st200cc compiler options therefore this chapter only lists the specific C additions Invoking the compiler The C compiler is invoked using the st200c command st200c lt argument gt where lt argument gt lt option gt lt input_file gt Examples st200c S fno exceptions file cxx produces file s st200c c fno exceptions file cxx produces file o Conflicting options are resolved by using the last option on the command line Any string that is not recognized as an option or a re
186. structs the compiler that the estimate of the number of the iterations of the loop the loop trip count estimate is n This is not an assertion that the loop effectively iterates n times A number of optimizations are affected by the pragma when the compiler has not already determined the exact trip count e basic block frequency estimation uses this information as an approximation of the loop trip count e unrolling and cross iteration optimizations are reduced if the given loop trip count estimate is low e software pipelining is limited if the estimate is low e automatic data prefetch generation is limited if the estimate is low R STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Loop optimization pragmas 55 Note 4 2 6 One scenario of usage is for for loops with trip counts of unknown values where the user knows that the approximate effective value is low pragma looptrip 4 for i 0 i lt n i a i b il This example avoids non beneficial optimizations On such loops the compiler trip count estimate without the pragma is 100 A second scenario is for while loops where the user knows that the approximate effective trip count is high pragma looptrip 100 while p s This example gives a better approximation of the weight of the loop Generally the compiler trip count estimate for a while loop is very low Possible error mess
187. summarizes the operator names used in the intrinsics description The reader must be familiar with the concepts of modular saturating rounding and fractional arithmetic Pay particular attention to the Remarks column in Table 32 ADCS 7508723H pan Description Remarks _add_ Modular addition _addc_ Saturating addition _sub_ Modular subtraction _subc_ Saturating subtraction _neg_ Modular negate _negc_ Saturating negate min Minimum _max Maximum _abs_ Modular absolute value _absc_ Saturating absolute value _dist_ Distance _shr_ Right shift Positive shift amount shifting more than integral operand size in bits is implementation defined _shrr_ Rounded right shift _shic_ Saturating left shift Positive shift amount shifting more than integral operand size in bits is implementation defined _mul_ Modular multiplication _mulc_ Saturating multiplication _mulrc_ Rounded saturating multiplication Table 32 ST200 intrinsic operator names STMicroelectronics Ka ST200 Micro Toolset User Manual PRELIMINARY DATA 128 Naming intrinsics ers Description Remarks _mulh_ High multiplication High part of classical multiplication _div_ Division Sign of Quotient is sign of algebraic quotient if inexact Iql lt D dl _dive_ Saturating fractional division _mod_ Modulus When Quotient q is defined q d Modulus D _modc_ Saturating f
188. t processors can be handled by using the core symbol defined by the C preprocessor __st220__ __st231__ In any case correct instruction bundling must occur for example bundling constraints and multiplication alignments Lia STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 122 7 1 5 7 1 6 hi PRELIMINARY DATA Introduction Restrictions e The compiler does not parse the assembler instruction template this means that it does not check if it is valid assembler input e Up to 10 operands results and clobbered registers are allowed e Multiple alternative constraints are not supported e At 03 optimization level the loop nest optimizer is disabled for loops containing asm statements Example The following function adds two unsigned integers completes a carry and obtains the 33 bit result through the addcg ST200 instruction The output is represented by 64 bits It uses both ordinary registers and boolean registers as input and output and shows that struct members can be used as C expressions to receive the computed result inline unsigned long long addcarry unsigned int t unsigned int s unsigned int c typedef union unsigned long long v_ i defined _ LITTLE ENDIAN _ struct unsigned int 1 unsigned int h_ lh elif defined _ BIG ENDIAN __ struct unsigned int h_ unsigned int 1_ 1h else error addcarry Unknown endianness endif _ui64 ui64 ui b4v
189. that the libinstrC a routines collect control flow frequencies and store the counts into a file when the program completes During the annotation step the compiler reads the frequency data from any available feedback data files and attaches the data to the code Annotation occurs at the same point of compilation that instrumentation occurred Later phases of the compiler for instance instruction cache optimization if conversion and code generation can use the data to guide optimization decisions gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 86 Interprocedural analysis optimization IPA 5 9 Interprocedural analysis optimization IPA 5 9 1 Introduction The ipa option enables interprocedural analysis The compiler identifies optimization opportunities across module boundaries It does this by extending the scope that is examined during optimization and inlining from a single module to multiple modules The ipa option must be included in both the compile and link phases The major benefits of IPA are e interprocedural constant propagation e interprocedural alias analysis e inter module inlining A more advanced use of IPA is function specialization cloning 5 9 2 Using IPA The only necessary option to trigger the IPA compilation is ipa No fundamental Makefile changes are necessary to the usual build process as the compiler driver takes care of all the necessary phase
190. the following sections I STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 76 PRELIMINARY DATA Data prefetching 5 5 1 Manual data prefetching 5 5 2 Note 1 void _ builtin prefetch const void addr You can insert calls to__builtin prefetch into code for which you know addresses of data in memory are likely to be accessed soon in order to generate a data prefetch instruction The value of addr is the address of the memory to prefetch Data prefetch does not generate faults if addr is invalid but the address expression itself must be valid For example a prefetch of p gt next does not fault if p gt next is not a valid address but evaluation does fault if p is not a valid address The following option controls whether the __builtin prefetchis accounted for this can be useful to measure the effect of the insertion of the builtin The m no builtin prefetch option disables or enables the _ builtin prefetch builtin throughout the compilation For example with mno builtin prefetch the compiler allows calls to__builtin prefetch in the source code however they are ignored Automatic data prefetching Automatic prefetching may be enabled by the command line option m no auto prefetch This option is only effective when optimization level 03 is selected 2 Automatic prefetching is disabled by default 57 Automatic prefetching inserts prefetch instructions for array references inside l
191. the processor These prefetch buffers are used to store prefetched data before a memory access move it to the data cache Profiling Before optimizing any application it is recommended that you analyze the critical areas of your code Profiling creates an instrumented program from your source code Each time this instrumented code is executed the instrumented program generates an information file that can be later displayed with the st200gprof tool This section is not a complete guide to profiling but a quick refresher on how to proceed with the compiler More details about using gprof can be found at http www gnu org software binutils manual gprof 2 9 1 gprof html Example st200cc 02 pg c o myexe After first run a file gmon out 000 is generated It can be viewed with st200gprof with the following command st200gprof myexe gmon out 000 After each run in the same directory the file name suffix part of the gmon out 000 is incremented so that profile information for the new run is available as gmon out 001 and so on The symbolic information available in the profile information can be augmented by using the st200cc g option when compiling the source code STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Call trace instrumentation 81 57 5 7 1 5 7 2 Call trace instrumentation This section describes the use of the finstrument functions and minstrument
192. tion disables the printing of warning messages Generate object file in spite of errors After an error message st200as normally produces no output With this option a output file is generated with possibly erroneous data I STMicroelectronics ST200 Micro Toolset User Manual PRELIMINARY DATA 194 Invoking the assembler 11 3 1 2 Arguments Except for any command line argument that begins with a hyphen is an option Each option changes the behavior of st200as No option changes the way another option works An option is a followed by one or more letters the case of the letters is important Some options expect exactly one parameter to follow them The parameter may either immediately follow the option letter or it may be the next command line argument In the following example the two command lines are equivalent st200as o my object file o mumble s st200as omy object file o mumble s 11 3 1 3 Input and output files The phrase source program abbreviated to source is used to describe the program input to one run of st200as The source program may be contained in one or more files how the source is partitioned into files does not change the meaning of the source By convention assembler source files have a s suffix The source program is a concatenation of the text in all the files in the order specified Two hyphens name the standard input explicitly as one of the files for st200as
193. to fill with the value of the first parameter word expression number data4 expression number real4 expression number These directives which are equivalent take one or more pairs of parameters separated by commas They assemble the value of the first expression into the next four bytes The second parameter in each pair is optional if present it specifies the number of consecutive 32 bit words to fill with the value of the first parameter It is expected that when real is used the expression represents a floating point number 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Assembler syntax 189 quad expression number data8 expression number real8 expression number These directives which are equivalent take one or more pairs of parameters separated by commas They assemble the value of the first expression into the next eight bytes The second parameter in each pair is optional if present it specifies the number of consecutive 64 bit words to fill with the value of the first parameter 11 2 9 4 Symbol directives equ symbol expression set symbol expression These directives which are equivalent set the value of symbol to expression This changes the symbol s value and type to conform to that of expression If the symbol was flagged as external see global then it remains external The value of a symbol can be set many times in the assemb
194. ult is ffor scope f no gnu keywords f no permissive When using fno gnu keywords typeof is not recognized as a keyword so that code can still use this word as an identifier The keyword __typeof__ can still be used instead The default is gnu keywords ansi implies fno gnu keywords fpermissive downgrades some diagnostics about non conformant code allowing some non conformant code to compile The default is fno permissive ftemplate depth n Set the maximum instantiation depth for template classes to n fmessage length n Try to format error messages so that they fit on lines of about n characters fdiagnostics show location once every line Instructs the diagnostic messages reporter to emit once or every line source location information Table 19 C code generation options Lia STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 36 Predefined macros 3 3 4 Directory and library options Table 20 lists the options that select header files libraries and compiler ezecutables Wa E ES nostdinc No predefined include search path Table 20 Directory options 3 4 Predefined macros Predefined macros are described in Table 21 Note 1 The macros defined by the C compiler are still relevant unless otherwise stated for example the macros defining the endianness and the core 2 The list of macros cur
195. umber of loop bodies created However the compiler cannot always statically determine the trip count When it cannot determine the trip count the compiler must also create residual code in case the unrolling factor is not a divisor of the loop trip count However it is possible for application writers to know the modular properties of some of the loops in their own code Bringing this accurate information to the compiler the residual code can be largely removed or better optimized Bringing inexact information on the trip count may lead to inexact code Be careful that the property asserted is valid in all cases gj STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 54 425 PRELIMINARY DATA Loop optimization pragmas The following example shows the use of the pragma loopmod void copychar unsigned char _ restrict p unsigned char q unsigned int sz int i assert sz 4 0 pragma loopmod 4 0 for i 0 i lt sz i pli alil The function copychar duplicates a byte stream whose size must be a multiple of 4 During unrolling and without the pragma the compiler would create a residual loop This is totally removed when the pragma information is asserted In this example the pragma does not provide the compiler with any information about the memory alignment of p or q which the compiler would need to generate word accesses after unrolling pragma looptrip This pragma in
196. void _ attribute_ noinline 3 int i ig i int main 3 1 3 is not marked for inlining pragma inline next 3 3 2 3 is not marked for inlining pragma defaultinline 3 3 3 3 is not marked for inlining printf result is d n ig STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Memory dependences in C programs 69 5 3 Memory dependences in C programs Precise memory dependencies analysis is key to compilation optimization since it enables the compiler to more freely schedule load instructions above store instructions By default a C compiler assumes that any pair of memory accesses which reference distinct types are not aliased that is memory dependent However real world cases almost always involves pointers to the same types that are actually un aliased the compiler cannot generally deduce this property and must rely on additional information This effect can be achieved either through the C language restrict keyword or with compiler option OPT alias value where possible values are listed in Table 28 value Description any The default Any pair of memory accesses may be aliased typed Any pair of memory accesses that reference distinct types are not aliased unnamed Assume pointers never point to global objects restrict Assume that different pointers never point to the same area disjoint Assume multiple pointer indirect
197. wed by a double equals sign followed by an expression This is equivalent to using the equ or set directives discussed later Symbols are not required to be defined before use however the current implementation of the assembler allocates space for long immediates whenever a symbol is undefined even if the symbol is eventually resolved to a value that can fit in a short immediate Example foo Lia STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual PRELIMINARY DATA 180 Assembler syntax 11 2 4 2 Local and global labels Labels defined with a double colon are global that is they are visible to all the subprograms being linked All other labels are local that is they are only visible in the source file where they are declared Example local_label global_label 11 2 4 3 Symbol names Symbol names are required to begin with a letter or one of _ The initial character may be followed by any string of digits letters and characters from the set _ The case of letters is significant oo is a different symbol from Foo e Local symbol names Local symbols may be defined for use in a given source file but are not represented in the object file for subsequent use by a linker or debugger By convention local symbol names begin 1 upper case L 2 or _ The assembler writes these symbols to the object file if the 1 option is used gt
198. with branch prediction information The return value is the value of exp which should be an integral expression The value of e must be a compile time constant The semantics of the built in are that it is expected that exp c hy ST Microelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Attributes 117 For example if builtin expect exp 0 foo would indicate that we do not expect to call oo since we expect exp to be zero __builtin_classify_type __builtin_classify_type ignores the value of the object considering only its data type It returns an enum describing what kind of type object is enum type class _ builtin classify type object enum type class no type class 1 void type class integer type class char type class enumeral type class boolean type class pointer type class reference type class offset type class real type class complez type class function type class method type class record type class union type class array type class string type class set type class file type class lang type class builtin_prefetch void _ builtin prefetch const void addr This function causes the compiler to generate a pft instruction for address addr There are two optional arguments rwand locality These arguments are currently ignored by the ST200 compiler Automatic prefetching is not performed upon arrays that have the built in function _ builtin pref
199. xample ldw d r2 O r1 Sr2 lt probe Sri1 Sr1 0 57 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Assembler syntax 187 Prefetch The ST200 processors provide a group of prefetch operations that bring data into the appropriate cache but do not modify a register and do not stall the machine on a cache miss Example pft 8 r8 fetch the cache line containing 8 Sr8 11 2 9 Assembler directives The ST200 assembler supports most ofthe standard directives provided by the GNU assembler Only a subset of the directives accepted by the assembler is described here 11 2 9 1 Alignment directives At present the directives that insert values into memory or change the location counter are only valid in the data section Using them in the text section is reported as an error align abs expr abs expr This pads the location counter in the current section to the specified boundary The first expression which must be absolute is the alignment request in bytes The alignment request must be a power of 2 The second optional expression also absolute gives the value to be stored in the padding bytes The default case is to pad by 0 Example align 8 The preceding advances the location counter until it is a multiple of 8 If the location counter is already a multiple of 8 no change is made 11 2 9 2 Section directives section name Assemble the following stateme
200. xe ly static input myexe po cmd binopt output myexe op icacheopt or st200cc c 02 Wo cmd binopt o myexe 10 5 Warning and error messages 10 5 1 binopt hy symbol s is not a function ignored warning Symbol defined in an icg file is not a function no need of trace file in static mode error use trace option with static No profile_info section present BB frequency is 1 warning there are not any profile info section in the input object file whereas static is used binopt estimated all call counts to 1 Sorry too many start functions max is d error user gives more than 128 start functions Sorry too many ignored functions max is d error user gives more than 128 ignored functions unknown argument s error wrong option Too many arguments error too many arguments on the command line need executable error input object file is not given to binopt fatal error opening file s error cannot access input object file STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA Warning and error messages 173 e Not a bfd_object error input object file is not recognized e ERROR Unable to find any calls in the trace file s error in profile mode cannot find any calls e need trace file error trace file has been omitted e Can t build graph for daVinci with this algorithm
201. y 89 95 fzero initialized in bss 19 G g 16 80 88 gbd See st200gbd GNU 1 13 97 105 ASM 119 122 asm 39 C See st200c gas 175 187 style labeled elements in initializers 108 GNU89 13 57 GNU99 13 gprof See st200gprof H H 12 help 11 hidden visibility 114 host 26 I ICache optimization 151 174 icache algo 157 159 icache mapping 156 161 icache opt 156 161 icacheopt 166 173 options 167 171 icache profile 158 161 icache static 157 161 Idirectory 23 TEEE 754 178 imodels c 123 130 imodels h 130 imodels o 131 initialize 108 INLINE 60 61 must 60 inline 61 inline keyword 60 inlining 59 63 pragmas 63 68 internal visibility 115 interprocedural analysis 86 intrinsics 123 145 include files 130 absolute distance 136 absolute value 136 add 135 STMicroelectronics ST200 Micro Toolset User Manual ADCS 7508723H PRELIMINARY DATA 201 bit and byte ordering 144 IPA plimit 88 bit manipulation 140 IPA space 88 clamp 140 IPA specfile 88 divide 138 ee T o 101 104 109 high precision fractional arithmetic 143 i insert 140 iso646 h 27 integer 32 bit 142 ISO9899 left shift 137 1990 13 long long 142 199409 13 maximum 136 1999 13 minimum 135 miscellaneous 139 K modulus 138 keep 11 multiply 137 multiply high 139 L multiply special 138 negate 135 l library 23 population count 144 146 label right shift 137 assembler 179 round 140 Ldirectory 23
202. y code from using it Using this option generally requires rebuilding a set of libraries either with the same option for C C code or to take into account that this option has been used Examples st200cc ffixed reg r62 b0 st200cc ffixed reg r24 r62 Table 10 Code generation options 57 ST200 Micro Toolset User Manual STMicroelectronics ADCS 7508723H PRELIMINARY DATA Command line options 19 Description f no zero initialized in bss st200cc by default puts variables that are initialized to zero into the bss section that is cleared upon startup Note that the fno zero initialized in bss option turns off this behavior because some programs explicitly rely on variables going to the data section If fno zero initialized in bss is specified then zero initialized variables are placed in the data section The default is fzero initialized in bss fdismissible load The fdismissible load option globally enables and the fno dismissible load globally disables the fno dismissible load LO ct a dismissible load generation in all compiler phases Dismissible loads are only generated at Os 02 and 03 optimization levels Libraries for example libc libgec are generally built with 02 or Os options and thus may include legitimate dismissible loads This is the case even if fno dismissible load is used to compile the application The fno dismissible load option reduces performance and does not redu
203. y one statement all load memory accesses can be performed before all store memory accesses which means that a vector version of the loop can be written In practice unless the target processor is a real vector processor the compiler does not decompose vectorizable loops as described Rather it uses the vectorizable property of the original loop to remove dependences between memory accesses In the example above the first loop is vectorizable provided that a and b do not overlap The second loop is also vectorizable if the assertion 4 i lt i holds for all i Another useful property for loop optimizations is when a loop is parallelizable This property can be enforced on a loop by using the pragma loopdep PARALLEL A parallelizable loop is one for which memory accesses that reference a given memory location may occur only in the same iteration of the loop As a result the sequence of memory accesses of the original loop can be changed in any way that preserves the relative order of memory accesses originating from the same loop iteration Note that a parallelizable loop is always vectorizable so the pragma loopdep PARALLEL is stronger but less generally applicable than the pragma loopdep VECTOR In the example above the first loop is not parallelizable The second loop is parallelizable if the assertion 4 i i holds for all i The last useful property for loop optimizations is when a loop is liberal This property can be enf
204. y to functions The constructor attribute causes the function to be called automatically before execution enters main Similarly the destructor attribute causes the function to be called automatically after exit void initdata void __attribute_ constructor void terminatedata void _ attribute _ destructor ky STMicroelectronics ADCS 7508723H ST200 Micro Toolset User Manual 114 6 3 2 6 3 3 I I 57 PRELIMINARY DATA Attributes Optimization This section applies only to functions noreturn Enables a function to be declared that cannot return such as abort or exit Useful indication to optimizers void byebye _ attribute noreturn malloc Used to tell the compiler that a function returns a pointer that cannot alias anything Useful indication to optimizers void get block int _ attribute malloc Visibility attributes The visibility attributes are supported as follows _ attribute _ visibility visibility type __ attribute visibility visibility type where visibility type can be default hidden protected internal default Default visibility is the normal case for ELF This value is available for the visibility attribute to override other options that may change the assumed visibility of symbols hidden Hidden visibility indicates that the symbol will not be placed into the dynamic symbol table so that no other module

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