:shock: 各位大哥：谁有gcc的详细配置文档啊？

madcolt

各位大哥：谁有gcc的详细配置文档啊？贴上来让小弟一看，谢谢！

madcolt

看来各位大哥都不想帮忙啊！不过小弟还是找到了官方的资料，供像小弟一样情况的兄弟参考：
Installing GCC: Configuration
Like most GNU software, GCC must be configured before it can be built. This document describes the recommended configuration procedure for both native and cross targets.

We use srcdir to refer to the toplevel source directory for GCC; we use objdir to refer to the toplevel build/object directory.

If you obtained the sources via CVS, srcdir must refer to the top gcc directory, the one where the MAINTAINERS can be found, and not its gcc subdirectory, otherwise the build will fail.

If either srcdir or objdir is located on an automounted NFS file system, the shell's built-in pwd command will return temporary pathnames. Using these can lead to various sorts of build problems. To avoid this issue, set the PWDCMD environment variable to an automounter-aware pwd command, e.g., pawd or amq -w, during the configuration and build phases.

First, we highly recommend that GCC be built into a separate directory than the sources which does not reside within the source tree. This is how we generally build GCC; building where srcdir == objdir should still work, but doesn't get extensive testing; building where objdir is a subdirectory of srcdir is unsupported.

If you have previously built GCC 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 or issues a message like "don't know how to make distclean" it probably means that the directory is already suitably clean. However, with the recommended method of building in a separate objdir, you should simply use a different objdir for each target.

Second, when configuring a native system, either cc or gcc must be in your path or you must set CC in your environment before running configure. Otherwise the configuration scripts may fail.

Note that the bootstrap compiler and the resulting GCC must be link compatible, else the bootstrap will fail with linker errors about incompatible object file formats. Several multilibed targets are affected by this requirement, see host/target specific installation notes.

To configure GCC:

        % mkdir objdir
        % cd objdir
        % srcdir/configure [options] [target]
     

Target specification

    * GCC has code to correctly determine the correct value for target for nearly all native systems. Therefore, we highly recommend you not provide a configure target when configuring a native compiler.
    * target must be specified as --target=target when configuring a cross compiler; examples of valid targets would be i960-rtems, m68k-coff, sh-elf, etc.
    * Specifying just target instead of --target=target implies that the host defaults to target.

Options specification

Use options to override several configure time options for GCC. A list of supported options follows; configure --help may list other options, but those not listed below may not work and should not normally be used.

--prefix=dirname
    Specify the toplevel installation directory. This is the recommended way to install the tools into a directory other than the default. The toplevel installation directory defaults to /usr/local.

    We highly recommend against dirname being the same or a subdirectory of objdir or vice versa. If specifying a directory beneath a user's home directory tree, some shells will not expand dirname correctly if it contains the ~ metacharacter; use $HOME instead.

    The following standard autoconf options are supported. Normally you should not need to use these options.

    --exec-prefix=dirname
        Specify the toplevel installation directory for architecture-dependent files. The default is prefix.
    --bindir=dirname
        Specify the installation directory for the executables called by users (such as gcc and g++). The default is exec-prefix/bin.
    --libdir=dirname
        Specify the installation directory for object code libraries and internal data files of GCC. The default is exec-prefix/lib.
    --libexecdir=dirname
        Specify the installation directory for internal executables of GCC. The default is exec-prefix/libexec.
    --with-slibdir=dirname
        Specify the installation directory for the shared libgcc library. The default is libdir.
    --infodir=dirname
        Specify the installation directory for documentation in info format. The default is prefix/info.
    --datadir=dirname
        Specify the installation directory for some architecture-independent data files referenced by GCC. The default is prefix/share.
    --mandir=dirname
        Specify the installation directory for manual pages. The default is prefix/man. (Note that the manual pages are only extracts from the full GCC manuals, which are provided in Texinfo format. The manpages are derived by an automatic conversion process from parts of the full manual.)
    --with-gxx-include-dir=dirname
        Specify the installation directory for G++ header files. The default is prefix/include/g++-v3.


--program-prefix=prefix
    GCC supports some transformations of the names of its programs when installing them. This option prepends prefix to the names of programs to install in bindir (see above). For example, specifying --program-prefix=foo- would result in gcc being installed as /usr/local/bin/foo-gcc.
--program-suffix=suffix
    Appends suffix to the names of programs to install in bindir (see above). For example, specifying --program-suffix=-3.1 would result in gcc being installed as /usr/local/bin/gcc-3.1.
--program-transform-name=pattern
    Applies the sed script pattern to be applied to the names of programs to install in bindir (see above). pattern has to consist of one or more basic sed editing commands, separated by semicolons. For example, if you want the gcc program name to be transformed to the installed program /usr/local/bin/myowngcc and the g++ program name to be transformed to /usr/local/bin/gspecial++ without changing other program names, you could use the pattern --program-transform-name='s/^gcc$/myowngcc/; s/^g++$/gspecial++/' to achieve this effect.

    All three options can be combined and used together, resulting in more complex conversion patterns. As a basic rule, prefix (and suffix) are prepended (appended) before further transformations can happen with a special transformation script pattern.

    As currently implemented, this option only takes effect for native builds; cross compiler binaries' names are not transformed even when a transformation is explicitly asked for by one of these options.

    For native builds, some of the installed programs are also installed with the target alias in front of their name, as in i686-pc-linux-gnu-gcc. All of the above transformations happen before the target alias is prepended to the name - so, specifying --program-prefix=foo- and program-suffix=-3.1, the resulting binary would be installed as /usr/local/bin/i686-pc-linux-gnu-foo-gcc-3.1.

    As a last shortcoming, none of the installed Ada programs are transformed yet, which will be fixed in some time.
--with-local-prefix=dirname
    Specify the installation directory for local include files. The default is /usr/local. Specify this option if you want the compiler to search directory dirname/include for locally installed header files instead of /usr/local/include.

    You should specify --with-local-prefix only if your site has a different convention (not /usr/local) for where to put site-specific files.

    The default value for --with-local-prefix is /usr/local regardless of the value of --prefix. Specifying --prefix has no effect on which directory GCC searches for local header files. This may seem counterintuitive, but actually it is logical.

    The purpose of --prefix is to specify where to install GCC. The local header files in /usr/local/include--if you put any in that directory--are not part of GCC. They are part of other programs--perhaps many others. (GCC installs its own header files in another directory which is based on the --prefix value.)

    Both the local-prefix include directory and the GCC-prefix include directory are part of GCC's "system include" directories. Although these two directories are not fixed, they need to be searched in the proper order for the correct processing of the include_next directive. The local-prefix include directory is searched before the GCC-prefix include directory. Another characteristic of system include directories is that pedantic warnings are turned off for headers in these directories.

    Some autoconf macros add -I directory options to the compiler command line, to ensure that directories containing installed packages' headers are searched. When directory is one of GCC's system include directories, GCC will ignore the option so that system directories continue to be processed in the correct order. This may result in a search order different from what was specified but the directory will still be searched.

    GCC automatically searches for ordinary libraries using GCC_EXEC_PREFIX. Thus, when the same installation prefix is used for both GCC and packages, GCC will automatically search for both headers and libraries. This provides a configuration that is easy to use. GCC behaves in a manner similar to that when it is installed as a system compiler in /usr.

    Sites that need to install multiple versions of GCC may not want to use the above simple configuration. It is possible to use the --program-prefix, --program-suffix and --program-transform-name options to install multiple versions into a single directory, but it may be simpler to use different prefixes and the --with-local-prefix option to specify the location of the site-specific files for each version. It will then be necessary for users to specify explicitly the location of local site libraries (e.g., with LIBRARY_PATH).

    The same value can be used for both --with-local-prefix and --prefix provided it is not /usr. This can be used to avoid the default search of /usr/local/include.

    Do not specify /usr as the --with-local-prefix! The directory you use for --with-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.

    Indications are that people who use this option use it based on mistaken ideas of what it is for. People use it as if it specified where to install part of GCC. Perhaps they make this assumption because installing GCC creates the directory.
--enable-shared[=package[,...]]
    Build shared versions of libraries, if shared libraries are supported on the target platform. Unlike GCC 2.95.x and earlier, shared libraries are enabled by default on all platforms that support shared libraries, except for libobjc which is built as a static library only by default.

    If a list of packages is given as an argument, build shared libraries only for the listed packages. For other packages, only static libraries will be built. Package names currently recognized in the GCC tree are libgcc (also known as gcc), libstdc++ (not libstdc++-v3), libffi, zlib, boehm-gc and libjava. Note that libobjc does not recognize itself by any name, so, if you list package names in --enable-shared, you will only get static Objective-C libraries. libf2c and libiberty do not support shared libraries at all.

    Use --disable-shared to build only static libraries. Note that --disable-shared does not accept a list of package names as argument, only --enable-shared does.
--with-gnu-as
    Specify that the compiler should assume that the assembler it finds is the GNU assembler. However, this does not modify the rules to find an assembler and will result in confusion if the assembler found is not actually the GNU assembler. (Confusion may also result if the compiler finds the GNU assembler but has not been configured with --with-gnu-as.) If you have more than one assembler installed on your system, you may want to use this option in connection with --with-as=pathname.

    The following systems are the only ones where it makes a difference whether you use the GNU assembler. On any other system, --with-gnu-as has no effect.

        * hppa1.0-any-any
        * hppa1.1-any-any
        * i386-any-sysv
        * m68k-bull-sysv
        * m68k-hp-hpux
        * m68000-hp-hpux
        * m68000-att-sysv
        * any-lynx-lynxos
        * mips-any
        * sparc-sun-solaris2.any
        * sparc64-any-solaris2.any

    On the systems listed above (except for the HP-PA, the SPARC, for ISC on the 386, and for mips-sgi-irix5.*), if you use the GNU assembler, you should also use the GNU linker (and specify --with-gnu-ld).
--with-as=pathname
    Specify that the compiler should use the assembler pointed to by pathname, rather than the one found by the standard rules to find an assembler, which are:

        * Check the libexec/gcc/target/version directory, where libexec defaults to exec-prefix/libexec and exec-prefix defaults to prefix which defaults to /usr/local unless overridden by the --prefix=pathname switch described above. target is the target system triple, such as sparc-sun-solaris2.7, and version denotes the GCC version, such as 3.0.
        * Check operating system specific directories (e.g. /usr/ccs/bin on Sun Solaris 2).

    Note that these rules do not check for the value of PATH. You may want to use --with-as if no assembler is installed in the directories listed above, or if you have multiple assemblers installed and want to choose one that is not found by the above rules.
--with-gnu-ld
    Same as --with-gnu-as but for the linker.
--with-ld=pathname
    Same as --with-as but for the linker.
--with-stabs
    Specify that stabs debugging information should be used instead of whatever format the host normally uses. Normally GCC uses the same debug format as the host system.

    On MIPS based systems and on Alphas, you must specify whether you want GCC 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, GCC uses the ECOFF debugging format by default; if you prefer BSD stabs, specify --with-stabs when you configure GCC.

    No matter which default you choose when you configure GCC, 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.
--disable-multilib
    Specify that multiple target libraries to support different target variants, calling conventions, etc should not be built. The default is to build a predefined set of them.

    Some targets provide finer-grained control over which multilibs are built (e.g., --disable-softfloat):

    arc-*-elf*
        biendian.
    arm-*-*
        fpu, 26bit, underscore, interwork, biendian, nofmult.
    m68*-*-*
        softfloat, m68881, m68000, m68020.
    mips*-*-*
        single-float, biendian, softfloat.
    powerpc*-*-*, rs6000*-*-*
        aix64, pthread, softfloat, powercpu, powerpccpu, powerpcos, biendian, sysv, aix.


--enable-threads
    Specify that the target supports threads. This affects the Objective-C compiler and runtime library, and exception handling for other languages like C++ and Java. On some systems, this is the default.

    In general, the best (and, in many cases, the only known) threading model available will be configured for use. Beware that on some systems, gcc has not been taught what threading models are generally available for the system. In this case, --enable-threads is an alias for --enable-threads=single.
--disable-threads
    Specify that threading support should be disabled for the system. This is an alias for --enable-threads=single.
--enable-threads=lib
    Specify that lib is the thread support library. This affects the Objective-C compiler and runtime library, and exception handling for other languages like C++ and Java. The possibilities for lib are:

    aix
        AIX thread support.
    dce
        DCE thread support.
    gnat
        Ada tasking support. For non-Ada programs, this setting is equivalent to single. When used in conjunction with the Ada run time, it causes GCC to use the same thread primitives as Ada uses. This option is necessary when using both Ada and the back end exception handling, which is the default for most Ada targets.
    mach
        Generic MACH thread support, known to work on NeXTSTEP. (Please note that the file needed to support this configuration, gthr-mach.h, is missing and thus this setting will cause a known bootstrap failure.)
    no
        This is an alias for single.
    posix
        Generic POSIX thread support.
    rtems
        RTEMS thread support.
    single
        Disable thread support, should work for all platforms.
    solaris
        Sun Solaris 2 thread support.
    vxworks
        VxWorks thread support.
    win32
        Microsoft Win32 API thread support.


--with-cpu=cpu
    Specify which cpu variant the compiler should generate code for by default. cpu will be used as the default value of the -mcpu= switch. This option is only supported on some targets, including ARM, i386, PowerPC, and SPARC.
--with-schedule=cpu
--with-arch=cpu
--with-tune=cpu
--with-abi=abi
--with-float=type
    These configure options provide default values for the -mschedule=, -march=, -mtune=, and -mabi= options and for -mhard-float or -msoft-float. As with --with-cpu, which switches will be accepted and acceptable values of the arguments depend on the target.
--enable-altivec
    Specify that the target supports AltiVec vector enhancements. This option will adjust the ABI for AltiVec enhancements, as well as generate AltiVec code when appropriate. This option is only available for PowerPC systems.
--enable-target-optspace
    Specify that target libraries should be optimized for code space instead of code speed. This is the default for the m32r platform.
--disable-cpp
    Specify that a user visible cpp program should not be installed.
--with-cpp-install-dir=dirname
    Specify that the user visible cpp program should be installed in prefix/dirname/cpp, in addition to bindir.
--enable-initfini-array
    Force the use of sections .init_array and .fini_array (instead of .init and .fini) for constructors and destructors. Option --disable-initfini-array has the opposite effect. If neither option is specified, the configure script will try to guess whether the .init_array and .fini_array sections are supported and, if they are, use them.
--enable-maintainer-mode
    The build rules that regenerate the GCC master message catalog gcc.pot are normally disabled. This is because it can only be rebuilt if the complete source tree is present. If you have changed the sources and want to rebuild the catalog, configuring with --enable-maintainer-mode will enable this. Note that you need a recent version of the gettext tools to do so.
--enable-generated-files-in-srcdir
    Neither the .c and .h files that are generated from bison and flex nor the info manuals and man pages that are built from the .texi files are present in the CVS development tree. When building GCC from that development tree, or from a snapshot which are created from CVS, then those generated files are placed in your build directory, which allows for the source to be in a readonly directory.

    If you configure with --enable-generated-files-in-srcdir then those generated files will go into the source directory. This is mainly intended for generating release or prerelease tarballs of the GCC sources, since it is not a requirement that the users of source releases to have flex, bison, or makeinfo.
--enable-version-specific-runtime-libs
    Specify that runtime libraries should be installed in the compiler specific subdirectory (libdir/gcc) rather than the usual places. In addition, libstdc++'s include files will be installed into libdir unless you overruled it by using --with-gxx-include-dir=dirname. Using this option is particularly useful if you intend to use several versions of GCC in parallel. This is currently supported by libf2c and libstdc++, and is the default for libobjc which cannot be changed in this case.
--enable-languages=lang1,lang2,...
    Specify that only a particular subset of compilers and their runtime libraries should be built. For a list of valid values for langN you can issue the following command in the gcc directory of your GCC source tree:

          grep language= */config-lang.in
         

    Currently, you can use any of the following: ada, c, c++, f77, java, objc. Building the Ada compiler has special requirements, see below.
    If you do not pass this flag, all languages available in the gcc sub-tree will be configured. Re-defining LANGUAGES when calling make bootstrap does not work anymore, as those language sub-directories might not have been configured!
--disable-libgcj
    Specify that the run-time libraries used by GCJ should not be built. This is useful in case you intend to use GCJ with some other run-time, or you're going to install it separately, or it just happens not to build on your particular machine. In general, if the Java front end is enabled, the GCJ libraries will be enabled too, unless they're known to not work on the target platform. If GCJ is enabled but libgcj isn't built, you may need to port it; in this case, before modifying the top-level configure.in so that libgcj is enabled by default on this platform, you may use --enable-libgcj to override the default.
--with-dwarf2
    Specify that the compiler should use DWARF 2 debugging information as the default.
--enable-win32-registry
--enable-win32-registry=key
--disable-win32-registry
    The --enable-win32-registry option enables Windows-hosted GCC to look up installations paths in the registry using the following key:

          HKEY_LOCAL_MACHINE\SOFTWARE\Free Software Foundation\key
         

    key defaults to GCC version number, and can be overridden by the --enable-win32-registry=key option. Vendors and distributors who use custom installers are encouraged to provide a different key, perhaps one comprised of vendor name and GCC version number, to avoid conflict with existing installations. This feature is enabled by default, and can be disabled by --disable-win32-registry option. This option has no effect on the other hosts.
--nfp
    Specify that the machine does not have a floating point unit. This option only applies to m68k-sun-sunosn. On any other system, --nfp has no effect.
--enable-werror
--disable-werror
--enable-werror=yes
--enable-werror=no
    When you specify this option, it controls whether certain files in the compiler are built with -Werror in bootstrap stage2 and later. If you don't specify it, -Werror is turned on for the main development trunk. However it defaults to off for release branches and final releases. The specific files which get -Werror are controlled by the Makefiles.
--enable-checking
--enable-checking=list
    When you specify this option, the compiler is built to perform checking of tree node types when referencing fields of that node, and some other internal consistency checks. This does not change the generated code, but adds error checking within the compiler. This will slow down the compiler and may only work properly if you are building the compiler with GCC. This is on by default when building from CVS or snapshots, but off for releases. More control over the checks may be had by specifying list; the categories of checks available are misc, tree, gc, rtl, rtlflag, fold, gcac and valgrind. The check valgrind requires the external valgrind simulator, available from http://valgrind.kde.org/. The default when list is not specified is misc,tree,gc,rtlflag; the checks rtl, gcac and valgrind are very expensive.
--enable-coverage

--enable-coverage=level
    With this option, the compiler is built to collect self coverage information, every time it is run. This is for internal development purposes, and only works when the compiler is being built with gcc. The level argument controls whether the compiler is built optimized or not, values are opt and noopt. For coverage analysis you want to disable optimization, for performance analysis you want to enable optimization. When coverage is enabled, the default level is without optimization.
--enable-nls
--disable-nls
    The --enable-nls option enables Native Language Support (NLS), which lets GCC output diagnostics in languages other than American English. Native Language Support is enabled by default if not doing a canadian cross build. The --disable-nls option disables NLS.
--with-included-gettext
    If NLS is enabled, the --with-included-gettext option causes the build procedure to prefer its copy of GNU gettext.
--with-catgets
    If NLS is enabled, and if the host lacks gettext but has the inferior catgets interface, the GCC build procedure normally ignores catgets and instead uses GCC's copy of the GNU gettext library. The --with-catgets option causes the build procedure to use the host's catgets in this situation.
--with-libiconv-prefix=dir
    Search for libiconv header files in dir/include and libiconv library files in dir/lib.
--with-system-zlib
    Use installed zlib rather than that included with GCC. This option only applies if the Java front end is being built.
--enable-obsolete
    Enable configuration for an obsoleted system. If you attempt to configure GCC for a system (build, host, or target) which has been obsoleted, and you do not specify this flag, configure will halt with an error message.

    All support for systems which have been obsoleted in one release of GCC is removed entirely in the next major release, unless someone steps forward to maintain the port.

Some options which only apply to building cross compilers:

--with-sysroot
--with-sysroot=dir
    Tells GCC to consider dir as the root of a tree that contains a (subset of) the root filesystem of the target operating system. Target system headers, libraries and run-time object files will be searched in there. The specified directory is not copied into the install tree, unlike the options --with-headers and --with-libs that this option obsoletes. The default value, in case --with-sysroot is not given an argument, is ${gcc_tooldir}/sys-root. If the specified directory is a subdirectory of ${exec_prefix}, then it will be found relative to the GCC binaries if the installation tree is moved.
--with-headers
--with-headers=dir
    Deprecated in favor of --with-sysroot. Specifies that target headers are available when building a cross compiler. The dir argument specifies a directory which has the target include files. These include files will be copied into the gcc install directory. This option with the dir argument is required when building a cross compiler, if prefix/target/sys-include doesn't pre-exist. If prefix/target/sys-include does pre-exist, the dir argument may be omitted. fixincludes will be run on these files to make them compatible with GCC.
--without-headers
    Tells GCC not use any target headers from a libc when building a cross compiler. When crossing to GNU/Linux, you need the headers so gcc can build the exception handling for libgcc. See CrossGCC for more information on this option.
--with-libs
--with-libs=``dir1 dir2 ... dirN''
    Deprecated in favor of --with-sysroot. Specifies a list of directories which contain the target runtime libraries. These libraries will be copied into the gcc install directory. If the directory list is omitted, this option has no effect.
--with-newlib
    Specifies that newlib is being used as the target C library. This causes __eprintf to be omitted from libgcc.a on the assumption that it will be provided by newlib.

Note that each --enable option has a corresponding --disable option and that each --with option has a corresponding --without option.

Installing GCC: Building
Now that GCC is configured, you are ready to build the compiler and runtime libraries.

We highly recommend that GCC be built using GNU make; other versions may work, then again they might not. GNU make is required for compiling GNAT (the Ada compiler) and the Java runtime library.

(For example, many broken versions of make will fail if you use the recommended setup where objdir is different from srcdir. Other broken versions may recompile parts of the compiler when installing the compiler.)

Some commands executed when making the compiler may fail (return a nonzero status) and be ignored by make. These failures, which are often due to files that were not found, are expected, and can safely be ignored.

It is normal to have compiler warnings when compiling certain files. Unless you are a GCC developer, you can generally ignore these warnings unless they cause compilation to fail. Developers should attempt to fix any warnings encountered, however they can temporarily continue past warnings-as-errors by specifying the configure flag --disable-werror.

On certain old systems, defining certain environment variables such as CC can interfere with the functioning of make.

If you encounter seemingly strange errors when trying to build the compiler in a directory other than the source directory, it could be because you have previously configured the compiler in the source directory. Make sure you have done all the necessary preparations.

If you build GCC on a BSD system using a directory stored in an old System V file system, problems may occur in running fixincludes if the System V file system doesn't support symbolic links. These problems result in a failure to fix the declaration of size_t in sys/types.h. If you find that size_t is a signed type and that type mismatches occur, this could be the cause.

The solution is not to use such a directory for building GCC.

When building from CVS or snapshots, or if you modify parser sources, you need the Bison parser generator installed. Any version 1.25 or later should work; older versions may also work. If you do not modify parser sources, releases contain the Bison-generated files and you do not need Bison installed to build them.

When building from CVS or snapshots, or if you modify Texinfo documentation, you need version 4.2 or later of Texinfo installed if you want Info documentation to be regenerated. Releases contain Info documentation pre-built for the unmodified documentation in the release.
Building a native compiler

For a native build issue the command make bootstrap. This will build the entire GCC system, which includes the following steps:

    * Build host tools necessary to build the compiler such as texinfo, bison, gperf.
    * Build target tools for use by the compiler such as binutils (bfd, binutils, gas, gprof, ld, and opcodes) if they have been individually linked or moved into the top level GCC source tree before configuring.
    * Perform a 3-stage bootstrap of the compiler.
    * Perform a comparison test of the stage2 and stage3 compilers.
    * Build runtime libraries using the stage3 compiler from the previous step.

If you are short on disk space you might consider make bootstrap-lean instead. This is identical to make bootstrap except that object files from the stage1 and stage2 of the 3-stage bootstrap of the compiler are deleted as soon as they are no longer needed.

If you want to save additional space during the bootstrap and in the final installation as well, you can build the compiler binaries without debugging information as in the following example. This will save roughly 40% of disk space both for the bootstrap and the final installation. (Libraries will still contain debugging information.)

          make CFLAGS='-O' LIBCFLAGS='-g -O2' \
            LIBCXXFLAGS='-g -O2 -fno-implicit-templates' bootstrap
     

If you wish to use non-default GCC flags when compiling the stage2 and stage3 compilers, set BOOT_CFLAGS on the command line when doing make bootstrap. Non-default optimization flags are less well tested here than the default of -g -O2, but should still work. In a few cases, you may find that you need to specify special flags such as -msoft-float here to complete the bootstrap; or, if the native compiler miscompiles the stage1 compiler, you may need to work around this, by choosing BOOT_CFLAGS to avoid the parts of the stage1 compiler that were miscompiled, or by using make bootstrap4 to increase the number of stages of bootstrap.

If you used the flag --enable-languages=... to restrict the compilers to be built, only those you've actually enabled will be built. This will of course only build those runtime libraries, for which the particular compiler has been built. Please note, that re-defining LANGUAGES when calling make bootstrap does not work anymore!

If the comparison of stage2 and stage3 fails, this normally indicates that the stage2 compiler has compiled GCC incorrectly, and is therefore a potentially serious bug which you should investigate and report. (On a few systems, meaningful comparison of object files is impossible; they always appear "different". If you encounter this problem, you will need to disable comparison in the Makefile.)
Building a cross compiler

We recommend reading the crossgcc FAQ for information about building cross compilers.

When building a cross compiler, it is not generally possible to do a 3-stage bootstrap of the compiler. This makes for an interesting problem as parts of GCC can only be built with GCC.

To build a cross compiler, we first recommend building and installing a native compiler. You can then use the native GCC compiler to build the cross compiler. The installed native compiler needs to be GCC version 2.95 or later.

Assuming you have already installed a native copy of GCC and configured your cross compiler, issue the command make, which performs the following steps:

    * Build host tools necessary to build the compiler such as texinfo, bison, gperf.
    * Build target tools for use by the compiler such as binutils (bfd, binutils, gas, gprof, ld, and opcodes) if they have been individually linked or moved into the top level GCC source tree before configuring.
    * Build the compiler (single stage only).
    * Build runtime libraries using the compiler from the previous step.

Note that if an error occurs in any step the make process will exit.

If you are not building GNU binutils in the same source tree as GCC, you will need a cross-assembler and cross-linker installed before configuring GCC. Put them in the directory prefix/target/bin. Here is a table of the tools you should put in this directory:

as
    This should be the cross-assembler.
ld
    This should be the cross-linker.
ar
    This should be the cross-archiver: a program which can manipulate archive files (linker libraries) in the target machine's format.
ranlib
    This should be a program to construct a symbol table in an archive file.

The installation of GCC will find these programs in that directory, and copy or link them to the proper place to for the cross-compiler to find them when run later.

The easiest way to provide these files is to build the Binutils package. Configure it with the same --host and --target options that you use for configuring GCC, then build and install them. They install their executables automatically into the proper directory. Alas, they do not support all the targets that GCC supports.

If you are not building a C library in the same source tree as GCC, you should also provide the target libraries and headers before configuring GCC, specifying the directories with --with-sysroot or --with-headers and --with-libs. Many targets also require "start files" such as crt0.o and crtn.o which are linked into each executable. There may be several alternatives for crt0.o, for use with profiling or other compilation options. Check your target's definition of STARTFILE_SPEC to find out what start files it uses.
Building in parallel

You can use make bootstrap MAKE="make -j 2" -j 2, or just make -j 2 bootstrap for GNU Make 3.79 and above, instead of make bootstrap to build GCC in parallel. You can also specify a bigger number, and in most cases using a value greater than the number of processors in your machine will result in fewer and shorter I/O latency hits, thus improving overall throughput; this is especially true for slow drives and network filesystems.
Building the Ada compiler

In order to build GNAT, the Ada compiler, you need a working GNAT compiler (GNAT version 3.14 or later, or GCC version 3.1 or later), including GNAT tools such as gnatmake and gnatlink, since the Ada front end is written in Ada (with some GNAT-specific extensions), and GNU make.

configure does not test whether the GNAT installation works and has a sufficiently recent version; if too old a GNAT version is installed, the build will fail unless --enable-languages is used to disable building the Ada front end.

At the moment, the GNAT library and several tools for GNAT are not built by make bootstrap. For a native build, you have to invoke make gnatlib_and_tools in the objdir/gcc subdirectory before proceeding with the next steps. For a cross build, you need to invoke make gnatlib cross-gnattools ada.all.cross. For a canadian cross you only need to invoke make cross-gnattools; the GNAT library would be the same as the one built for the cross compiler.

For example, you can build a native Ada compiler by issuing the following commands (assuming make is GNU make):

         cd objdir
         srcdir/configure --enable-languages=c,ada
         cd objdir
         make bootstrap
         cd gcc
         make gnatlib_and_tools
         cd ..
     

Currently, when compiling the Ada front end, you cannot use the parallel build feature described in the previous section.
Building with profile feedback

It is possible to use profile feedback to optimize the compiler itself. This should result in a faster compiler binary. Experiments done on x86 using gcc 3.3 showed approximately 7 percent speedup on compiling C programs. To bootstrap compiler with profile feedback, use make profiledbootstrap.

When make profiledbootstrap is run, it will first build a stage1 compiler. This compiler is used to build a stageprofile compiler instrumented to collect execution counts of instruction and branch probabilities. Then runtime libraries are compiled with profile collected. Finally a stagefeedback compiler is built using the information collected.

Unlike make bootstrap several additional restrictions apply. The compiler used to build stage1 needs to support a 64-bit integral type. It is recommended to only use GCC for this. Also parallel make is currently not supported since collisions in profile collecting may occur.

在.profile里配:
export PATH=$PATH:/usr/local/bin
export LIBPATH=$LIBPATH:/usr/local/lib
export MANPATH=$MANPATH:/usr/local/man
export CC=gcc