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GNU Info File | 1994-11-23 | 32.6 KB | 727 lines

This is Info file gcc.info, produced by Makeinfo-1.55 from the input file gcc.texi. This file documents the use and the internals of the GNU compiler. Published by the Free Software Foundation 675 Massachusetts Avenue Cambridge, MA 02139 USA Copyright (C) 1988, 1989, 1992, 1993, 1994 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the sections entitled "GNU General Public License," "Funding for Free Software," and "Protect Your Freedom--Fight `Look And Feel'" are included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the sections entitled "GNU General Public License," "Funding for Free Software," and "Protect Your Freedom--Fight `Look And Feel'", and this permission notice, may be included in translations approved by the Free Software Foundation instead of in the original English. File: gcc.info, Node: Environment Variables, Next: Running Protoize, Prev: Code Gen Options, Up: Invoking GCC Environment Variables Affecting GNU CC ====================================== This section describes several environment variables that affect how GNU CC operates. They work by specifying directories or prefixes to use when searching for various kinds of files. Note that you can also specify places to search using options such as `-B', `-I' and `-L' (*note Directory Options::.). These take precedence over places specified using environment variables, which in turn take precedence over those specified by the configuration of GNU CC. *Note Driver::. `TMPDIR' If `TMPDIR' is set, it specifies the directory to use for temporary files. GNU CC uses temporary files to hold the output of one stage of compilation which is to be used as input to the next stage: for example, the output of the preprocessor, which is the input to the compiler proper. `GCC_EXEC_PREFIX' If `GCC_EXEC_PREFIX' is set, it specifies a prefix to use in the names of the subprograms executed by the compiler. No slash is added when this prefix is combined with the name of a subprogram, but you can specify a prefix that ends with a slash if you wish. If GNU CC cannot find the subprogram using the specified prefix, it tries looking in the usual places for the subprogram. The default value of `GCC_EXEC_PREFIX' is `PREFIX/lib/gcc-lib/MACHINE/VERSION/' where PREFIX is the value of `prefix' when you ran the `configure' script and MACHINE and VERSION are the configuration name and version number of GNU CC, respectively. Other prefixes specified with `-B' take precedence over this prefix. This prefix is also used for finding files such as `crt0.o' that are used for linking. In addition, the prefix is used in an unusual way in finding the directories to search for header files. For each of the standard directories whose name normally begins with `/usr/local/lib/gcc-lib' (more precisely, with the value of `GCC_INCLUDE_DIR'), GNU CC tries replacing that beginning with the specified prefix to produce an alternate directory name. Thus, with `-Bfoo/', GNU CC will search `foo/bar' where it would normally search `/usr/local/lib/bar'. These alternate directories are searched first; the standard directories come next. `COMPILER_PATH' The value of `COMPILER_PATH' is a colon-separated list of directories, much like `PATH'. GNU CC tries the directories thus specified when searching for subprograms, if it can't find the subprograms using `GCC_EXEC_PREFIX'. `LIBRARY_PATH' The value of `LIBRARY_PATH' is a colon-separated list of directories, much like `PATH'. GNU CC tries the directories thus specified when searching for special linker files, if it can't find them using `GCC_EXEC_PREFIX'. Linking using GNU CC also uses these directories when searching for ordinary libraries for the `-l' option (but directories specified with `-L' come first). `C_INCLUDE_PATH' `CPLUS_INCLUDE_PATH' `OBJC_INCLUDE_PATH' These environment variables pertain to particular languages. Each variable's value is a colon-separated list of directories, much like `PATH'. When GNU CC searches for header files, it tries the directories listed in the variable for the language you are using, after the directories specified with `-I' but before the standard header file directories. `DEPENDENCIES_OUTPUT' If this variable is set, its value specifies how to output dependencies for Make based on the header files processed by the compiler. This output looks much like the output from the `-M' option (*note Preprocessor Options::.), but it goes to a separate file, and is in addition to the usual results of compilation. The value of `DEPENDENCIES_OUTPUT' can be just a file name, in which case the Make rules are written to that file, guessing the target name from the source file name. Or the value can have the form `FILE TARGET', in which case the rules are written to file FILE using TARGET as the target name. File: gcc.info, Node: Running Protoize, Prev: Environment Variables, Up: Invoking GCC Running Protoize ================ The program `protoize' is an optional part of GNU C. You can use it to add prototypes to a program, thus converting the program to ANSI C in one respect. The companion program `unprotoize' does the reverse: it removes argument types from any prototypes that are found. When you run these programs, you must specify a set of source files as command line arguments. The conversion programs start out by compiling these files to see what functions they define. The information gathered about a file FOO is saved in a file named `FOO.X'. After scanning comes actual conversion. The specified files are all eligible to be converted; any files they include (whether sources or just headers) are eligible as well. But not all the eligible files are converted. By default, `protoize' and `unprotoize' convert only source and header files in the current directory. You can specify additional directories whose files should be converted with the `-d DIRECTORY' option. You can also specify particular files to exclude with the `-x FILE' option. A file is converted if it is eligible, its directory name matches one of the specified directory names, and its name within the directory has not been excluded. Basic conversion with `protoize' consists of rewriting most function definitions and function declarations to specify the types of the arguments. The only ones not rewritten are those for varargs functions. `protoize' optionally inserts prototype declarations at the beginning of the source file, to make them available for any calls that precede the function's definition. Or it can insert prototype declarations with block scope in the blocks where undeclared functions are called. Basic conversion with `unprotoize' consists of rewriting most function declarations to remove any argument types, and rewriting function definitions to the old-style pre-ANSI form. Both conversion programs print a warning for any function declaration or definition that they can't convert. You can suppress these warnings with `-q'. The output from `protoize' or `unprotoize' replaces the original source file. The original file is renamed to a name ending with `.save'. If the `.save' file already exists, then the source file is simply discarded. `protoize' and `unprotoize' both depend on GNU CC itself to scan the program and collect information about the functions it uses. So neither of these programs will work until GNU CC is installed. Here is a table of the options you can use with `protoize' and `unprotoize'. Each option works with both programs unless otherwise stated. `-B DIRECTORY' Look for the file `SYSCALLS.c.X' in DIRECTORY, instead of the usual directory (normally `/usr/local/lib'). This file contains prototype information about standard system functions. This option applies only to `protoize'. `-c COMPILATION-OPTIONS' Use COMPILATION-OPTIONS as the options when running `gcc' to produce the `.X' files. The special option `-aux-info' is always passed in addition, to tell `gcc' to write a `.X' file. Note that the compilation options must be given as a single argument to `protoize' or `unprotoize'. If you want to specify several `gcc' options, you must quote the entire set of compilation options to make them a single word in the shell. There are certain `gcc' arguments that you cannot use, because they would produce the wrong kind of output. These include `-g', `-O', `-c', `-S', and `-o' If you include these in the COMPILATION-OPTIONS, they are ignored. `-C' Rename files to end in `.C' instead of `.c'. This is convenient if you are converting a C program to C++. This option applies only to `protoize'. `-g' Add explicit global declarations. This means inserting explicit declarations at the beginning of each source file for each function that is called in the file and was not declared. These declarations precede the first function definition that contains a call to an undeclared function. This option applies only to `protoize'. `-i STRING' Indent old-style parameter declarations with the string STRING. This option applies only to `protoize'. `unprotoize' converts prototyped function definitions to old-style function definitions, where the arguments are declared between the argument list and the initial `{'. By default, `unprotoize' uses five spaces as the indentation. If you want to indent with just one space instead, use `-i " "'. `-k' Keep the `.X' files. Normally, they are deleted after conversion is finished. `-l' Add explicit local declarations. `protoize' with `-l' inserts a prototype declaration for each function in each block which calls the function without any declaration. This option applies only to `protoize'. `-n' Make no real changes. This mode just prints information about the conversions that would have been done without `-n'. `-N' Make no `.save' files. The original files are simply deleted. Use this option with caution. `-p PROGRAM' Use the program PROGRAM as the compiler. Normally, the name `gcc' is used. `-q' Work quietly. Most warnings are suppressed. `-v' Print the version number, just like `-v' for `gcc'. If you need special compiler options to compile one of your program's source files, then you should generate that file's `.X' file specially, by running `gcc' on that source file with the appropriate options and the option `-aux-info'. Then run `protoize' on the entire set of files. `protoize' will use the existing `.X' file because it is newer than the source file. For example: gcc -Dfoo=bar file1.c -aux-info protoize *.c You need to include the special files along with the rest in the `protoize' command, even though their `.X' files already exist, because otherwise they won't get converted. *Note Protoize Caveats::, for more information on how to use `protoize' successfully. File: gcc.info, Node: Installation, Next: C Extensions, Prev: Invoking GCC, Up: Top Installing GNU CC ***************** * Menu: * Configurations:: Configurations Supported by GNU CC. * Other Dir:: Compiling in a separate directory (not where the source is). * Cross-Compiler:: Building and installing a cross-compiler. * Sun Install:: See below for installation on the Sun. * VMS Install:: See below for installation on VMS. * Collect2:: How `collect2' works; how it finds `ld'. * Header Dirs:: Understanding the standard header file directories. Here is the procedure for installing GNU CC on a Unix system. See *Note VMS Install::, for VMS systems. In this section we assume you compile in the same directory that contains the source files; see *Note Other Dir::, to find out how to compile in a separate directory on Unix systems. You cannot install GNU C by itself on MSDOS; it will not compile under any MSDOS compiler except itself. You need to get the complete compilation package DJGPP, which includes binaries as well as sources, and includes all the necessary compilation tools and libraries. 1. If you have built GNU CC previously in the same directory for a different target machine, do `make distclean' to delete all files that might be invalid. One of the files this deletes is `Makefile'; if `make distclean' complains that `Makefile' does not exist, it probably means that the directory is already suitably clean. 2. On a System V release 4 system, make sure `/usr/bin' precedes `/usr/ucb' in `PATH'. The `cc' command in `/usr/ucb' uses libraries which have bugs. 3. Specify the host, build and target machine configurations. You do this by running the file `configure'. The "build" machine is the system which you are using, the "host" machine is the system where you want to run the resulting compiler (normally the build machine), and the "target" machine is the system for which you want the compiler to generate code. If you are building a compiler to produce code for the machine it runs on (a native compiler), you normally do not need to specify any operands to `configure'; it will try to guess the type of machine you are on and use that as the build, host and target machines. So you don't need to specify a configuration when building a native compiler unless `configure' cannot figure out what your configuration is or guesses wrong. In those cases, specify the build machine's "configuration name" with the `--build' option; the host and target will default to be the same as the build machine. (If you are building a cross-compiler, see *Note Cross-Compiler::.) Here is an example: ./configure --build=sparc-sun-sunos4.1 A configuration name may be canonical or it may be more or less abbreviated. A canonical configuration name has three parts, separated by dashes. It looks like this: `CPU-COMPANY-SYSTEM'. (The three parts may themselves contain dashes; `configure' can figure out which dashes serve which purpose.) For example, `m68k-sun-sunos4.1' specifies a Sun 3. You can also replace parts of the configuration by nicknames or aliases. For example, `sun3' stands for `m68k-sun', so `sun3-sunos4.1' is another way to specify a Sun 3. You can also use simply `sun3-sunos', since the version of SunOS is assumed by default to be version 4. `sun3-bsd' also works, since `configure' knows that the only BSD variant on a Sun 3 is SunOS. You can specify a version number after any of the system types, and some of the CPU types. In most cases, the version is irrelevant, and will be ignored. So you might as well specify the version if you know it. See *Note Configurations::, for a list of supported configuration names and notes on many of the configurations. You should check the notes in that section before proceding any further with the installation of GNU CC. There are four additional options you can specify independently to describe variant hardware and software configurations. These are `--with-gnu-as', `--with-gnu-ld', `--with-stabs' and `--nfp'. `--with-gnu-as' If you will use GNU CC with the GNU assembler (GAS), you should declare this by using the `--with-gnu-as' option when you run `configure'. Using this option does not install GAS. It only modifies the output of GNU CC to work with GAS. Building and installing GAS is up to you. Conversely, if you *do not* wish to use GAS and do not specify `--with-gnu-as' when building GNU CC, it is up to you to make sure that GAS is not installed. GNU CC searches for a program named `as' in various directories; if the program it finds is GAS, then it runs GAS. If you are not sure where GNU CC finds the assembler it is using, try specifying `-v' when you run it. The systems where it makes a difference whether you use GAS are `hppa1.0-ANY-ANY', `hppa1.1-ANY-ANY', `i386-ANY-sysv', `i386-ANY-isc', `i860-ANY-bsd', `m68k-bull-sysv', `m68k-hp-hpux', `m68k-sony-bsd', `m68k-altos-sysv', `m68000-hp-hpux', `m68000-att-sysv', and `mips-ANY'). On any other system, `--with-gnu-as' has no effect. On the systems listed above (except for the HP-PA, for ISC on the 386, and for `mips-sgi-irix5.*'), if you use GAS, you should also use the GNU linker (and specify `--with-gnu-ld'). `--with-gnu-ld' Specify the option `--with-gnu-ld' if you plan to use the GNU linker with GNU CC. This option does not cause the GNU linker to be installed; it just modifies the behavior of GNU CC to work with the GNU linker. Specifically, it inhibits the installation of `collect2', a program which otherwise serves as a front-end for the system's linker on most configurations. `--with-stabs' On MIPS based systems and on Alphas, you must specify whether you want GNU CC to create the normal ECOFF debugging format, or to use BSD-style stabs passed through the ECOFF symbol table. The normal ECOFF debug format cannot fully handle languages other than C. BSD stabs format can handle other languages, but it only works with the GNU debugger GDB. Normally, GNU CC uses the ECOFF debugging format by default; if you prefer BSD stabs, specify `--with-stabs' when you configure GNU CC. No matter which default you choose when you configure GNU CC, the user can use the `-gcoff' and `-gstabs+' options to specify explicitly the debug format for a particular compilation. `--with-stabs' is meaningful on the ISC system on the 386, also, if `--with-gas' is used. It selects use of stabs debugging information embedded in COFF output. This kind of debugging information supports C++ well; ordinary COFF debugging information does not. `--with-stabs' is also meaningful on 386 systems running SVR4. It selects use of stabs debugging information embedded in ELF output. The C++ compiler currently (2.6.0) does not support the DWARF debugging information normally used on 386 SVR4 platforms; stabs provide a workable alternative. This requires gas and gdb, as the normal SVR4 tools can not generate or interpret stabs. `--nfp' On certain systems, you must specify whether the machine has a floating point unit. These systems include `m68k-sun-sunosN' and `m68k-isi-bsd'. On any other system, `--nfp' currently has no effect, though perhaps there are other systems where it could usefully make a difference. The `configure' script searches subdirectories of the source directory for other compilers that are to be integrated into GNU CC. The GNU compiler for C++, called G++ is in a subdirectory named `cp'. `configure' inserts rules into `Makefile' to build all of those compilers. Here we spell out what files will be set up by `configure'. Normally you need not be concerned with these files. * A symbolic link named `config.h' is made to the top-level config file for the machine you will run the compiler on (*note Config::.). This file is responsible for defining information about the host machine. It includes `tm.h'. The top-level config file is located in the subdirectory `config'. Its name is always `xm-SOMETHING.h'; usually `xm-MACHINE.h', but there are some exceptions. If your system does not support symbolic links, you might want to set up `config.h' to contain a `#include' command which refers to the appropriate file. * A symbolic link named `tconfig.h' is made to the top-level config file for your target machine. This is used for compiling certain programs to run on that machine. * A symbolic link named `tm.h' is made to the machine-description macro file for your target machine. It should be in the subdirectory `config' and its name is often `MACHINE.h'. * A symbolic link named `md' will be made to the machine description pattern file. It should be in the `config' subdirectory and its name should be `MACHINE.md'; but MACHINE is often not the same as the name used in the `tm.h' file because the `md' files are more general. * A symbolic link named `aux-output.c' will be made to the output subroutine file for your machine. It should be in the `config' subdirectory and its name should be `MACHINE.c'. * The command file `configure' also constructs the file `Makefile' by adding some text to the template file `Makefile.in'. The additional text comes from files in the `config' directory, named `t-TARGET' and `x-HOST'. If these files do not exist, it means nothing needs to be added for a given target or host. 4. The standard directory for installing GNU CC is `/usr/local/lib'. If you want to install its files somewhere else, specify `--prefix=DIR' when you run `configure'. Here DIR is a directory name to use instead of `/usr/local' for all purposes with one exception: the directory `/usr/local/include' is searched for header files no matter where you install the compiler. To override this name, use the `--local-prefix' option below. 5. Specify `--local-prefix=DIR' if you want the compiler to search directory `DIR/include' for locally installed header files *instead* of `/usr/local/include'. You should specify `--local-prefix' *only* if your site has a different convention (not `/usr/local') for where to put site-specific files. *Do not* specify `/usr' as the `--local-prefix'! The directory you use for `--local-prefix' *must not* contain any of the system's standard header files. If it did contain them, certain programs would be miscompiled (including GNU Emacs, on certain targets), because this would override and nullify the header file corrections made by the `fixincludes' script. 6. Make sure the Bison parser generator is installed. (This is unnecessary if the Bison output files `c-parse.c' and `cexp.c' are more recent than `c-parse.y' and `cexp.y' and you do not plan to change the `.y' files.) Bison versions older than Sept 8, 1988 will produce incorrect output for `c-parse.c'. 7. If you have chosen a configuration for GNU CC which requires other GNU tools (such as GAS or the GNU linker) instead of the standard system tools, install the required tools in the build directory under the names `as', `ld' or whatever is appropriate. This will enable the compiler to find the proper tools for compilation of the program `enquire'. Alternatively, you can do subsequent compilation using a value of the `PATH' environment variable such that the necessary GNU tools come before the standard system tools. 8. Build the compiler. Just type `make LANGUAGES=c' in the compiler directory. `LANGUAGES=c' specifies that only the C compiler should be compiled. The makefile normally builds compilers for all the supported languages; currently, C, C++ and Objective C. However, C is the only language that is sure to work when you build with other non-GNU C compilers. In addition, building anything but C at this stage is a waste of time. In general, you can specify the languages to build by typing the argument `LANGUAGES="LIST"', where LIST is one or more words from the list `c', `c++', and `objective-c'. If you have any additional GNU compilers as subdirectories of the GNU CC source directory, you may also specify their names in this list. Ignore any warnings you may see about "statement not reached" in `insn-emit.c'; they are normal. Also, warnings about "unknown escape sequence" are normal in `genopinit.c' and perhaps some other files. Likewise, you should ignore warnings about "constant is so large that it is unsigned" in `insn-emit.c' and `insn-recog.c'. Any other compilation errors may represent bugs in the port to your machine or operating system, and should be investigated and reported (*note Bugs::.). Some commercial compilers fail to compile GNU CC because they have bugs or limitations. For example, the Microsoft compiler is said to run out of macro space. Some Ultrix compilers run out of expression space; then you need to break up the statement where the problem happens. 9. If you are building a cross-compiler, stop here. *Note Cross-Compiler::. 10. Move the first-stage object files and executables into a subdirectory with this command: make stage1 The files are moved into a subdirectory named `stage1'. Once installation is complete, you may wish to delete these files with `rm -r stage1'. 11. If you have chosen a configuration for GNU CC which requires other GNU tools (such as GAS or the GNU linker) instead of the standard system tools, install the required tools in the `stage1' subdirectory under the names `as', `ld' or whatever is appropriate. This will enable the stage 1 compiler to find the proper tools in the following stage. Alternatively, you can do subsequent compilation using a value of the `PATH' environment variable such that the necessary GNU tools come before the standard system tools. 12. Recompile the compiler with itself, with this command: make CC="stage1/xgcc -Bstage1/" CFLAGS="-g -O" This is called making the stage 2 compiler. The command shown above builds compilers for all the supported languages. If you don't want them all, you can specify the languages to build by typing the argument `LANGUAGES="LIST"'. LIST should contain one or more words from the list `c', `c++', `objective-c', and `proto'. Separate the words with spaces. `proto' stands for the programs `protoize' and `unprotoize'; they are not a separate language, but you use `LANGUAGES' to enable or disable their installation. If you are going to build the stage 3 compiler, then you might want to build only the C language in stage 2. Once you have built the stage 2 compiler, if you are short of disk space, you can delete the subdirectory `stage1'. On a 68000 or 68020 system lacking floating point hardware, unless you have selected a `tm.h' file that expects by default that there is no such hardware, do this instead: make CC="stage1/xgcc -Bstage1/" CFLAGS="-g -O -msoft-float" 13. If you wish to test the compiler by compiling it with itself one more time, install any other necessary GNU tools (such as GAS or the GNU linker) in the `stage2' subdirectory as you did in the `stage1' subdirectory, then do this: make stage2 make CC="stage2/xgcc -Bstage2/" CFLAGS="-g -O" This is called making the stage 3 compiler. Aside from the `-B' option, the compiler options should be the same as when you made the stage 2 compiler. But the `LANGUAGES' option need not be the same. The command shown above builds compilers for all the supported languages; if you don't want them all, you can specify the languages to build by typing the argument `LANGUAGES="LIST"', as described above. If you do not have to install any additional GNU tools, you may use the command make bootstrap LANGUAGES=LANGUAGE-LIST BOOT_CFLAGS=OPTION-LIST instead of making `stage1', `stage2', and performing the two compiler builds. 14. Then compare the latest object files with the stage 2 object files--they ought to be identical, aside from time stamps (if any). On some systems, meaningful comparison of object files is impossible; they always appear "different." This is currently true on Solaris and probably on all systems that use ELF object file format. On some versions of Irix on SGI machines and OSF/1 on Alpha systems, you will not be able to compare the files without specifying `-save-temps'; see the description of individual systems above to see if you get comparison failures. You may have similar problems on other systems. Use this command to compare the files: make compare This will mention any object files that differ between stage 2 and stage 3. Any difference, no matter how innocuous, indicates that the stage 2 compiler has compiled GNU CC incorrectly, and is therefore a potentially serious bug which you should investigate and report (*note Bugs::.). If your system does not put time stamps in the object files, then this is a faster way to compare them (using the Bourne shell): for file in *.o; do cmp $file stage2/$file done If you have built the compiler with the `-mno-mips-tfile' option on MIPS machines, you will not be able to compare the files. 15. Build the Objective C library (if you have built the Objective C compiler). Here is the command to do this: make objc-runtime CC="stage2/xgcc -Bstage2/" CFLAGS="-g -O" 16. Install the compiler driver, the compiler's passes and run-time support with `make install'. Use the same value for `CC', `CFLAGS' and `LANGUAGES' that you used when compiling the files that are being installed. One reason this is necessary is that some versions of Make have bugs and recompile files gratuitously when you do this step. If you use the same variable values, those files will be recompiled properly. For example, if you have built the stage 2 compiler, you can use the following command: make install CC="stage2/xgcc -Bstage2/" CFLAGS="-g -O" LANGUAGES="LIST" This copies the files `cc1', `cpp' and `libgcc.a' to files `cc1', `cpp' and `libgcc.a' in the directory `/usr/local/lib/gcc-lib/TARGET/VERSION', which is where the compiler driver program looks for them. Here TARGET is the target machine type specified when you ran `configure', and VERSION is the version number of GNU CC. This naming scheme permits various versions and/or cross-compilers to coexist. This also copies the driver program `xgcc' into `/usr/local/bin/gcc', so that it appears in typical execution search paths. On some systems, this command causes recompilation of some files. This is usually due to bugs in `make'. You should either ignore this problem, or use GNU Make. *Warning: there is a bug in `alloca' in the Sun library. To avoid this bug, be sure to install the executables of GNU CC that were compiled by GNU CC. (That is, the executables from stage 2 or 3, not stage 1.) They use `alloca' as a built-in function and never the one in the library.* (It is usually better to install GNU CC executables from stage 2 or 3, since they usually run faster than the ones compiled with some other compiler.) 17. Install the Objective C library (if you are installing the Objective C compiler). Here is the command to do this: make install-libobjc CC="stage2/xgcc -Bstage2/" CFLAGS="-g -O" 18. If you're going to use C++, it's likely that you need to also install the libg++ distribution. It should be available from the same place where you got the GNU C distribution. Just as GNU C does not distribute a C runtime library, it also does not include a C++ run-time library. All I/O functionality, special class libraries, etc., are available in the libg++ distribution.