Installing GNU CC
*****************

Here is the procedure for installing GNU CC on a Unix system.  See VMS Install, for VMS systems.  In this section we assume you compile in the same directory that contains the source files; see 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 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.

     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 Configurations, for a list of supported configuration names and notes on many of the configurations.  You should check the notes in that section before proceeding 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, ANY-lynx-lynxos, 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.

     --enable-objcthreads=TYPE
          Certain systems, notably Linux-based GNU systems, can't be relied on to supply a threads facility for the Objective C runtime and so will default to single-threaded runtime.  They may, however, have a library threads implementation available, in which case threads can be enabled with this option by supplying a suitable TYPE, probably posix.  The possibilities for TYPE are single, posix, win32, solaris, irix and mach.

     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 file named config.h is created that contains a #include of the top-level config file for the machine you will run the compiler on (see The Configuration File (Using and Porting GCC)).  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 file named tconfig.h is created which includes the top-level config file for your target machine.  This is used for compiling certain programs to run on that machine.

       * A file named tm.h is created which includes the machine-description macro file for your target machine.  It should be in the subdirectory config and its name is often MACHINE.h.

       * 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.

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

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

     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.

     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 GNU CC.  Perhaps they make this assumption because installing GNU CC creates the directory.

 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 and a warning about a comparison always being zero in enquire.o.  Any other compilation errors may represent bugs in the port to your machine or operating system, and should be investigated and reported (see 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.  See 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 -O2"

     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 -O2 -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 -O2"

     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 some systems that use ELF object file format.  On some versions of Irix on SGI machines and DEC Unix (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 (see 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. 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. It also copies the executables for compilers for other languages (e.g., cc1plus for C++) to the same directory.

     This also copies the driver program xgcc into /usr/local/bin/gcc, so that it appears in typical execution search paths.  It also copies gcc.1 into /usr/local/man/man1 and info pages into /usr/local/info.

     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.)

 16. 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.

 17. GNU CC includes a runtime library for Objective-C because it is an integral part of the language.  You can find the files associated with the library in the subdirectory objc.  The GNU Objective-C Runtime Library requires header files for the target's C library in order to be compiled,and also requires the header files for the target's thread library if you want thread support.  See Cross-Compilers and Header Files, for discussion about header files issues for cross-compilation.

     When you run configure, it picks the appropriate Objective-C thread implementation file for the target platform.  In some situations, you may wish to choose a different back-end as some platforms support multiple thread implementations or you may wish to disable thread support completely.  You do this by specifying a value for the OBJC_THREAD_FILE makefile variable on the command line when you run make, for example:

          make CC="stage2/xgcc -Bstage2/" CFLAGS="-g -O2" OBJC_THREAD_FILE=thr-single

     Below is a list of the currently available back-ends.

       * thr-single Disable thread support, should work for all platforms.

       * thr-decosf1 DEC OSF/1 thread support.

       * thr-irix SGI IRIX thread support.

       * thr-mach Generic MACH thread support, known to work on NEXTSTEP.

       * thr-os2 IBM OS/2 thread support.

       * thr-posix Generix POSIX thread support.

       * thr-pthreads PCThreads on Linux-based GNU systems.

       * thr-solaris SUN Solaris thread support.

       * thr-win32 Microsoft Win32 API thread support.

Configurations Supported by GNU CC
==================================

Here are the possible CPU types:

     1750a, a29k, alpha, arm, cN, clipper, dsp16xx, elxsi, h8300, hppa1.0, hppa1.1, i370, i386, i486, i586, i860, i960, m32r, m68000, m68k, m88k, mips, mipsel, mips64, mips64el, ns32k, powerpc, powerpcle, pyramid, romp, rs6000, sh, sparc, sparclite, sparc64, vax, we32k.

Here are the recognized company names.  As you can see, customary abbreviations are used rather than the longer official names.

     acorn, alliant, altos, apollo, apple, att, bull, cbm, convergent, convex, crds, dec, dg, dolphin, elxsi, encore, harris, hitachi, hp, ibm, intergraph, isi, mips, motorola, ncr, next, ns, omron, plexus, sequent, sgi, sony, sun, tti, unicom, wrs.

The company name is meaningful only to disambiguate when the rest of the information supplied is insufficient.  You can omit it, writing just CPU-SYSTEM, if it is not needed.  For example, vax-ultrix4.2 is equivalent to vax-dec-ultrix4.2.

Here is a list of system types:

     386bsd, aix, acis, amigaos, aos, aout, aux, bosx, bsd, clix, coff, ctix, cxux, dgux, dynix, ebmon, ecoff, elf, esix, freebsd, hms, genix, gnu, linux-gnu, hiux, hpux, iris, irix, isc, luna, lynxos, mach, minix, msdos, mvs, netbsd, newsos, nindy, ns, osf, osfrose, ptx, riscix, riscos, rtu, sco, sim, solaris, sunos, sym, sysv, udi, ultrix, unicos, uniplus, unos, vms, vsta, vxworks, winnt, xenix.

You can omit the system type; then configure guesses the operating system from the CPU and company.

You can add a version number to the system type; this may or may not make a difference.  For example, you can write bsd4.3 or bsd4.4 to distinguish versions of BSD.  In practice, the version number is most needed for sysv3 and sysv4, which are often treated differently.

If you specify an impossible combination such as i860-dg-vms, then you may get an error message from configure, or it may ignore part of the information and do the best it can with the rest. configure always prints the canonical name for the alternative that it used.  GNU CC does not support all possible alternatives.

Often a particular model of machine has a name.  Many machine names are recognized as aliases for CPU/company combinations.  Thus, the machine name sun3, mentioned above, is an alias for m68k-sun. Sometimes we accept a company name as a machine name, when the name is popularly used for a particular machine.  Here is a table of the known machine names:

     3300, 3b1, 3bN, 7300, altos3068, altos, apollo68, att-7300, balance, convex-cN, crds, decstation-3100, decstation, delta, encore, fx2800, gmicro, hp7NN, hp8NN, hp9k2NN, hp9k3NN, hp9k7NN, hp9k8NN, iris4d, iris, isi68, m3230, magnum, merlin, miniframe, mmax, news-3600, news800, news, next, pbd, pc532, pmax, powerpc, powerpcle, ps2, risc-news, rtpc, sun2, sun386i, sun386, sun3, sun4, symmetry, tower-32, tower.

Remember that a machine name specifies both the cpu type and the company name. If you want to install your own homemade configuration files, you can use local as the company name to access them.  If you use configuration CPU-local, the configuration name without the cpu prefix is used to form the configuration file names.

Thus, if you specify m68k-local, configuration uses files m68k.md, local.h, m68k.c, xm-local.h, t-local, and x-local, all in the directory config/m68k.

Here is a list of configurations that have special treatment or special things you must know:

1750a-*-*
     MIL-STD-1750A processors.

     The MIL-STD-1750A cross configuration produces output for as1750, an assembler/linker available under the GNU Public License for the 1750A. as1750 can be obtained at ftp://ftp.fta-berlin.de/pub/crossgcc/1750gals/. A similarly licensed simulator for the 1750A is available from same address.

     You should ignore a fatal error during the building of libgcc (libgcc is not yet implemented for the 1750A.)

     The as1750 assembler requires the file ms1750.inc, which is found in the directory config/1750a.

     GNU CC produced the same sections as the Fairchild F9450 C Compiler, namely:

     Normal
          The program code section.

     Static
          The read/write (RAM) data section.

     Konst
          The read-only (ROM) constants section.

     Init
          Initialization section (code to copy KREL to SREL).

     The smallest addressable unit is 16 bits (BITS_PER_UNIT is 16).  This means that type `char' is represented with a 16-bit word per character. The 1750A's "Load/Store Upper/Lower Byte" instructions are not used by GNU CC.

alpha-*-osf1
     Systems using processors that implement the DEC Alpha architecture and are running the DEC Unix (OSF/1) operating system, for example the DEC Alpha AXP systems.  (VMS on the Alpha is not currently supported by GNU CC.)

     GNU CC writes a .verstamp directive to the assembler output file unless it is built as a cross-compiler.  It gets the version to use from the system header file /usr/include/stamp.h.  If you install a new version of DEC Unix, you should rebuild GCC to pick up the new version stamp.

     Note that since the Alpha is a 64-bit architecture, cross-compilers from 32-bit machines will not generate code as efficient as that generated when the compiler is running on a 64-bit machine because many optimizations that depend on being able to represent a word on the target in an integral value on the host cannot be performed.  Building cross-compilers on the Alpha for 32-bit machines has only been tested in a few cases and may not work properly.

     make compare may fail on old versions of DEC Unix unless you add -save-temps to CFLAGS.  On these systems, the name of the assembler input file is stored in the object file, and that makes comparison fail if it differs between the stage1 and stage2 compilations.  The option -save-temps forces a fixed name to be used for the assembler input file, instead of a randomly chosen name in /tmp.  Do not add -save-temps unless the comparisons fail without that option.  If you add -save-temps, you will have to manually delete the .i and .s files after each series of compilations.

     GNU CC now supports both the native (ECOFF) debugging format used by DBX and GDB and an encapsulated STABS format for use only with GDB.  See the discussion of the --with-stabs option of configure above for more information on these formats and how to select them.

     There is a bug in DEC's assembler that produces incorrect line numbers for ECOFF format when the .align directive is used.  To work around this problem, GNU CC will not emit such alignment directives while writing ECOFF format debugging information even if optimization is being performed.  Unfortunately, this has the very undesirable side-effect that code addresses when -O is specified are different depending on whether or not -g is also specified.

     To avoid this behavior, specify -gstabs+ and use GDB instead of DBX.  DEC is now aware of this problem with the assembler and hopes to provide a fix shortly.

arc-*-elf
     Argonaut ARC processor. This configuration is intended for embedded systems.

arm-*-aout
     Advanced RISC Machines ARM-family processors.  These are often used in embedded applications.  There are no standard Unix configurations. This configuration corresponds to the basic instruction sequences and will produce a.out format object modules.

     You may need to make a variant of the file arm.h for your particular configuration.

arm-*-linuxaout
     Any of the ARM family processors running the Linux-based GNU system with the a.out binary format (ELF is not yet supported).  You must use version 2.8.1.0.7 or later of the Linux binutils, which you can download from sunsite.unc.edu:/pub/Linux/GCC and other mirror sites for Linux-based GNU systems.

arm-*-riscix
     The ARM2 or ARM3 processor running RISC iX, Acorn's port of BSD Unix.  If you are running a version of RISC iX prior to 1.2 then you must specify the version number during configuration.  Note that the assembler shipped with RISC iX does not support stabs debugging information; a new version of the assembler, with stabs support included, is now available from Acorn.

a29k
     AMD Am29k-family processors.  These are normally used in embedded applications.  There are no standard Unix configurations. This configuration corresponds to AMD's standard calling sequence and binary interface and is compatible with other 29k tools.

     You may need to make a variant of the file a29k.h for your particular configuration.

a29k-*-bsd
     AMD Am29050 used in a system running a variant of BSD Unix.

decstation-*
     DECstations can support three different personalities: Ultrix, DEC OSF/1, and OSF/rose.  To configure GCC for these platforms use the following configurations:

     decstation-ultrix
          Ultrix configuration.

     decstation-osf1
          Dec's version of OSF/1.

     decstation-osfrose
          Open Software Foundation reference port of OSF/1 which uses the OSF/rose object file format instead of ECOFF.  Normally, you would not select this configuration.

     The MIPS C compiler needs to be told to increase its table size for switch statements with the -Wf,-XNg1500 option in order to compile cp/parse.c.  If you use the -O2 optimization option, you also need to use -Olimit 3000. Both of these options are automatically generated in the Makefile that the shell script configure builds. If you override the CC make variable and use the MIPS compilers, you may need to add -Wf,-XNg1500 -Olimit 3000.

elxsi-elxsi-bsd
     The Elxsi's C compiler has known limitations that prevent it from compiling GNU C.  Please contact mrs@cygnus.com for more details.

dsp16xx
     A port to the AT&T DSP1610 family of processors.

h8300-*-*
     Hitachi H8/300 series of processors.

     The calling convention and structure layout has changed in release 2.6. All code must be recompiled.  The calling convention now passes the first three arguments in function calls in registers.  Structures are no longer a multiple of 2 bytes.

hppa*-*-*
     There are several variants of the HP-PA processor which run a variety of operating systems.  GNU CC must be configured to use the correct processor type and operating system, or GNU CC will not function correctly. The easiest way to handle this problem is to not specify a target when configuring GNU CC, the configure script will try to automatically determine the right processor type and operating system.

     -g does not work on HP-UX, since that system uses a peculiar debugging format which GNU CC does not know about.  However, -g will work if you also use GAS and GDB in conjunction with GCC.  We highly recommend using GAS for all HP-PA configurations.

     You should be using GAS-2.6 (or later) along with GDB-4.16 (or later).  These can be retrieved from all the traditional GNU ftp archive sites.

     GAS will need to be installed into a directory before /bin, /usr/bin, and /usr/ccs/bin in your search path.  You should install GAS before you build GNU CC.

     To enable debugging, you must configure GNU CC with the --with-gnu-as option before building.

i370-*-*
     This port is very preliminary and has many known bugs.  We hope to have a higher-quality port for this machine soon.

i386-*-linux-gnuoldld
     Use this configuration to generate a.out binaries on Linux-based GNU systems if you do not have gas/binutils version 2.5.2 or later installed. This is an obsolete configuration.

i386-*-linux-gnuaout
     Use this configuration to generate a.out binaries on Linux-based GNU systems. This configuration is being superseded. You must use gas/binutils version 2.5.2 or later.

i386-*-linux-gnu
     Use this configuration to generate ELF binaries on Linux-based GNU systems.  You must use gas/binutils version 2.5.2 or later.

i386-*-sco
     Compilation with RCC is recommended.  Also, it may be a good idea to link with GNU malloc instead of the malloc that comes with the system.

i386-*-sco3.2v4
     Use this configuration for SCO release 3.2 version 4.

i386-*-sco3.2v5*
     Use this for the SCO OpenServer Release family including 5.0.0, 5.0.2, 5.0.4, Internet FastStart 1.0, and Internet FastStart 1.1.

     GNU CC can generate ELF binaries (if you specify -melf) or COFF binaries (the default).  If you are going to build your compiler in ELF mode (once you have bootstrapped the first stage compiler) you must specify -melf as part of CC, not CFLAGS, for example as CC="stage1/xgcc -melf -Bstage1/" .  If you do not do this, the bootstrap will generate incorrect versions of libgcc.a.

     You must have TLS597 (from ftp.sco.com/TLS) installed for ELF binaries to work correctly. Note that Open Server 5.0.2 does need TLS597 installed.

     NOTE: You must follow the instructions about invoking make bootstrap because the native OpenServer compiler builds a cc1plus that will not correctly parse many valid C++ programs. You must do a make bootstrap if you are building with the native compiler.

i386-*-isc
     It may be a good idea to link with GNU malloc instead of the malloc that comes with the system.

     In ISC version 4.1, sed core dumps when building deduced.h.  Use the version of sed from version 4.0.

i386-*-esix
     It may be good idea to link with GNU malloc instead of the malloc that comes with the system.

i386-ibm-aix
     You need to use GAS version 2.1 or later, and LD from GNU binutils version 2.2 or later.

i386-sequent-bsd
     Go to the Berkeley universe before compiling.  In addition, you probably need to create a file named string.h containing just one line: #include <strings.h>.

i386-sequent-ptx1*
     Sequent DYNIX/ptx 1.x.

i386-sequent-ptx2*
     Sequent DYNIX/ptx 2.x.

i386-sun-sunos4
     You may find that you need another version of GNU CC to begin bootstrapping with, since the current version when built with the system's own compiler seems to get an infinite loop compiling part of libgcc2.c.  GNU CC version 2 compiled with GNU CC (any version) seems not to have this problem.

     See Sun Install, for information on installing GNU CC on Sun systems.

i[345]86-*-winnt3.5
     This version requires a GAS that has not yet been released.  Until it is, you can get a prebuilt binary version via anonymous ftp from cs.washington.edu:pub/gnat or cs.nyu.edu:pub/gnat. You must also use the Microsoft header files from the Windows NT 3.5 SDK. Find these on the CDROM in the /mstools/h directory dated 9/4/94.  You must use a fixed version of Microsoft linker made especially for NT 3.5, which is also is available on the NT 3.5 SDK CDROM.  If you do not have this linker, can you also use the linker from Visual C/C++ 1.0 or 2.0.

     Installing GNU CC for NT builds a wrapper linker, called ld.exe, which mimics the behaviour of Unix ld in the specification of libraries (-L and -l).  ld.exe looks for both Unix and Microsoft named libraries.  For example, if you specify -lfoo, ld.exe will look first for libfoo.a and then for foo.lib.

     You may install GNU CC for Windows NT in one of two ways, depending on whether or not you have a Unix-like shell and various Unix-like utilities.

      1. If you do not have a Unix-like shell and few Unix-like utilities, you will use a DOS style batch script called configure.bat.  Invoke it as configure winnt from an MSDOS console window or from the program manager dialog box.  configure.bat assumes you have already installed and have in your path a Unix-like sed program which is used to create a working Makefile from Makefile.in.

          Makefile uses the Microsoft Nmake program maintenance utility and the Visual C/C++ V8.00 compiler to build GNU CC.  You need only have the utilities sed and touch to use this installation method, which only automatically builds the compiler itself.  You must then examine what fixinc.winnt does, edit the header files by hand and build libgcc.a manually.

      2. The second type of installation assumes you are running a Unix-like shell, have a complete suite of Unix-like utilities in your path, and have a previous version of GNU CC already installed, either through building it via the above installation method or acquiring a pre-built binary.  In this case, use the configure script in the normal fashion.

i860-intel-osf1
     This is the Paragon. If you have version 1.0 of the operating system, see Installation Problems, for special things you need to do to compensate for peculiarities in the system.

*-lynx-lynxos
     LynxOS 2.2 and earlier comes with GNU CC 1.x already installed as /bin/gcc.  You should compile with this instead of /bin/cc. You can tell GNU CC to use the GNU assembler and linker, by specifying --with-gnu-as --with-gnu-ld when configuring.  These will produce COFF format object files and executables;  otherwise GNU CC will use the installed tools, which produce a.out format executables.

m32r-*-elf
     Mitsubishi M32R processor. This configuration is intended for embedded systems.

m68000-hp-bsd
     HP 9000 series 200 running BSD.  Note that the C compiler that comes with this system cannot compile GNU CC; contact law@cs.utah.edu to get binaries of GNU CC for bootstrapping.

m68k-altos
     Altos 3068.  You must use the GNU assembler, linker and debugger. Also, you must fix a kernel bug.  Details in the file README.ALTOS.

m68k-apple-aux
     Apple Macintosh running A/UX. You may configure GCC  to use either the system assembler and linker or the GNU assembler and linker.  You should use the GNU configuration if you can, especially if you also want to use GNU C++.  You enabled that configuration with + the --with-gnu-as and --with-gnu-ld options to configure.

     Note the C compiler that comes with this system cannot compile GNU CC.  You can fine binaries of GNU CC for bootstrapping on jagubox.gsfc.nasa.gov. You will also a patched version of /bin/ld there that raises some of the arbitrary limits found in the original.

m68k-att-sysv
     AT&T 3b1, a.k.a. 7300 PC.  Special procedures are needed to compile GNU CC with this machine's standard C compiler, due to bugs in that compiler.  You can bootstrap it more easily with previous versions of GNU CC if you have them.

     Installing GNU CC on the 3b1 is difficult if you do not already have GNU CC running, due to bugs in the installed C compiler.  However, the following procedure might work.  We are unable to test it.

      1. Comment out the #include "config.h" line near the start of cccp.c and do make cpp.  This makes a preliminary version of GNU cpp.

      2. Save the old /lib/cpp and copy the preliminary GNU cpp to that file name.

      3. Undo your change in cccp.c, or reinstall the original version, and do make cpp again.

      4. Copy this final version of GNU cpp into /lib/cpp.

      5. Replace every occurrence of obstack_free in the file tree.c with _obstack_free.

      6. Run make to get the first-stage GNU CC.

      7. Reinstall the original version of /lib/cpp.

      8. Now you can compile GNU CC with itself and install it in the normal fashion.

m68k-bull-sysv
     Bull DPX/2 series 200 and 300 with BOS-2.00.45 up to BOS-2.01. GNU CC works either with native assembler or GNU assembler. You can use GNU assembler with native coff generation by providing --with-gnu-as to the configure script or use GNU assembler with dbx-in-coff encapsulation by providing --with-gnu-as --stabs. For any problem with native assembler or for availability of the DPX/2 port of GAS, contact F.Pierresteguy@frcl.bull.fr.

m68k-crds-unox
     Use configure unos for building on Unos.

     The Unos assembler is named casm instead of as.  For some strange reason linking /bin/as to /bin/casm changes the behavior, and does not work.  So, when installing GNU CC, you should install the following script as as in the subdirectory where the passes of GCC are installed:

          #!/bin/sh
          casm $*

     The default Unos library is named libunos.a instead of libc.a.  To allow GNU CC to function, either change all references to -lc in gcc.c to -lunos or link /lib/libc.a to /lib/libunos.a.

     When compiling GNU CC with the standard compiler, to overcome bugs in the support of alloca, do not use -O when making stage 2. Then use the stage 2 compiler with -O to make the stage 3 compiler.  This compiler will have the same characteristics as the usual stage 2 compiler on other systems.  Use it to make a stage 4 compiler and compare that with stage 3 to verify proper compilation.

     (Perhaps simply defining ALLOCA in x-crds as described in the comments there will make the above paragraph superfluous.  Please inform us of whether this works.)

     Unos uses memory segmentation instead of demand paging, so you will need a lot of memory.  5 Mb is barely enough if no other tasks are running. If linking cc1 fails, try putting the object files into a library and linking from that library.

m68k-hp-hpux
     HP 9000 series 300 or 400 running HP-UX.  HP-UX version 8.0 has a bug in the assembler that prevents compilation of GNU CC.  To fix it, get patch PHCO_4484 from HP.

     In addition, if you wish to use gas --with-gnu-as you must use gas version 2.1 or later, and you must use the GNU linker version 2.1 or later.  Earlier versions of gas relied upon a program which converted the gas output into the native HP/UX format, but that program has not been kept up to date.  gdb does not understand that native HP/UX format, so you must use gas if you wish to use gdb.

m68k-sun
     Sun 3.  We do not provide a configuration file to use the Sun FPA by default, because programs that establish signal handlers for floating point traps inherently cannot work with the FPA.

     See Sun Install, for information on installing GNU CC on Sun systems.

m88k-*-svr3
     Motorola m88k running the AT&T/Unisoft/Motorola V.3 reference port. These systems tend to use the Green Hills C, revision 1.8.5, as the standard C compiler.  There are apparently bugs in this compiler that result in object files differences between stage 2 and stage 3.  If this happens, make the stage 4 compiler and compare it to the stage 3 compiler.  If the stage 3 and stage 4 object files are identical, this suggests you encountered a problem with the standard C compiler; the stage 3 and 4 compilers may be usable.

     It is best, however, to use an older version of GNU CC for bootstrapping if you have one.

m88k-*-dgux
     Motorola m88k running DG/UX.  To build 88open BCS native or cross compilers on DG/UX, specify the configuration name as m88k-*-dguxbcs and build in the 88open BCS software development environment.  To build ELF native or cross compilers on DG/UX, specify m88k-*-dgux and build in the DG/UX ELF development environment. You set the software development environment by issuing sde-target command and specifying either m88kbcs or m88kdguxelf as the operand.

     If you do not specify a configuration name, configure guesses the configuration based on the current software development environment.

m88k-tektronix-sysv3
     Tektronix XD88 running UTekV 3.2e.  Do not turn on optimization while building stage1 if you bootstrap with the buggy Green Hills compiler.  Also, The bundled LAI System V NFS is buggy so if you build in an NFS mounted directory, start from a fresh reboot, or avoid NFS all together. Otherwise you may have trouble getting clean comparisons between stages.

mips-mips-bsd
     MIPS machines running the MIPS operating system in BSD mode.  It's possible that some old versions of the system lack the functions memcpy, memcmp, and memset.  If your system lacks these, you must remove or undo the definition of TARGET_MEM_FUNCTIONS in mips-bsd.h.

     The MIPS C compiler needs to be told to increase its table size for switch statements with the -Wf,-XNg1500 option in order to compile cp/parse.c.  If you use the -O2 optimization option, you also need to use -Olimit 3000. Both of these options are automatically generated in the Makefile that the shell script configure builds. If you override the CC make variable and use the MIPS compilers, you may need to add -Wf,-XNg1500 -Olimit 3000.

mips-mips-riscos*
     The MIPS C compiler needs to be told to increase its table size for switch statements with the -Wf,-XNg1500 option in order to compile cp/parse.c.  If you use the -O2 optimization option, you also need to use -Olimit 3000. Both of these options are automatically generated in the Makefile that the shell script configure builds. If you override the CC make variable and use the MIPS compilers, you may need to add -Wf,-XNg1500 -Olimit 3000.

     MIPS computers running RISC-OS can support four different personalities: default, BSD 4.3, System V.3, and System V.4 (older versions of RISC-OS don't support V.4).  To configure GCC for these platforms use the following configurations:

     mips-mips-riscosrev
          Default configuration for RISC-OS, revision rev.

     mips-mips-riscosrevbsd
          BSD 4.3 configuration for RISC-OS, revision rev.

     mips-mips-riscosrevsysv4
          System V.4 configuration for RISC-OS, revision rev.

     mips-mips-riscosrevsysv
          System V.3 configuration for RISC-OS, revision rev.

     The revision rev mentioned above is the revision of RISC-OS to use.  You must reconfigure GCC when going from a RISC-OS revision 4 to RISC-OS revision 5.  This has the effect of avoiding a linker bug (see Installation Problems, for more details).

mips-sgi-*
     In order to compile GCC on an SGI running IRIX 4, the "c.hdr.lib" option must be installed from the CD-ROM supplied from Silicon Graphics. This is found on the 2nd CD in release 4.0.1.

     In order to compile GCC on an SGI running IRIX 5, the "compiler_dev.hdr" subsystem must be installed from the IDO CD-ROM supplied by Silicon Graphics.

     make compare may fail on version 5 of IRIX unless you add -save-temps to CFLAGS.  On these systems, the name of the assembler input file is stored in the object file, and that makes comparison fail if it differs between the stage1 and stage2 compilations.  The option -save-temps forces a fixed name to be used for the assembler input file, instead of a randomly chosen name in /tmp.  Do not add -save-temps unless the comparisons fail without that option.  If you do you -save-temps, you will have to manually delete the .i and .s files after each series of compilations.

     The MIPS C compiler needs to be told to increase its table size for switch statements with the -Wf,-XNg1500 option in order to compile cp/parse.c.  If you use the -O2 optimization option, you also need to use -Olimit 3000. Both of these options are automatically generated in the Makefile that the shell script configure builds. If you override the CC make variable and use the MIPS compilers, you may need to add -Wf,-XNg1500 -Olimit 3000.

     On Irix version 4.0.5F, and perhaps on some other versions as well, there is an assembler bug that reorders instructions incorrectly.  To work around it, specify the target configuration mips-sgi-irix4loser.  This configuration inhibits assembler optimization.

     In a compiler configured with target mips-sgi-irix4, you can turn off assembler optimization by using the -noasmopt option.  This compiler option passes the option -O0 to the assembler, to inhibit reordering.

     The -noasmopt option can be useful for testing whether a problem is due to erroneous assembler reordering.  Even if a problem does not go away with -noasmopt, it may still be due to assembler reordering---perhaps GNU CC itself was miscompiled as a result.

     To enable debugging under Irix 5, you must use GNU as 2.5 or later, and use the --with-gnu-as configure option when configuring gcc. GNU as is distributed as part of the binutils package.

mips-sony-sysv
     Sony MIPS NEWS.  This works in NEWSOS 5.0.1, but not in 5.0.2 (which uses ELF instead of COFF).  Support for 5.0.2 will probably be provided soon by volunteers.  In particular, the linker does not like the code generated by GCC when shared libraries are linked in.

ns32k-encore
     Encore ns32000 system.  Encore systems are supported only under BSD.

ns32k-*-genix
     National Semiconductor ns32000 system.  Genix has bugs in alloca and malloc; you must get the compiled versions of these from GNU Emacs.

ns32k-sequent
     Go to the Berkeley universe before compiling.  In addition, you probably need to create a file named string.h containing just one line: #include <strings.h>.

ns32k-utek
     UTEK ns32000 system (``merlin'').  The C compiler that comes with this system cannot compile GNU CC; contact tektronix!reed!mason to get binaries of GNU CC for bootstrapping.

romp-*-aos
romp-*-mach
     The only operating systems supported for the IBM RT PC are AOS and MACH.  GNU CC does not support AIX running on the RT.  We recommend you compile GNU CC with an earlier version of itself; if you compile GNU CC with hc, the Metaware compiler, it will work, but you will get mismatches between the stage 2 and stage 3 compilers in various files. These errors are minor differences in some floating-point constants and can be safely ignored; the stage 3 compiler is correct.

rs6000-*-aix
powerpc-*-aix
     Various early versions of each release of the IBM XLC compiler will not bootstrap GNU CC.  Symptoms include differences between the stage2 and stage3 object files, and errors when compiling libgcc.a or enquire.  Known problematic releases include: xlc-1.2.1.8, xlc-1.3.0.0 (distributed with AIX 3.2.5), and xlc-1.3.0.19.  Both xlc-1.2.1.28 and xlc-1.3.0.24 (PTF 432238) are known to produce working versions of GNU CC, but most other recent releases correctly bootstrap GNU CC.  Also, releases of AIX prior to AIX 3.2.4 include a version of the IBM assembler which does not accept debugging directives: assembler updates are available as PTFs.  Also, if you are using AIX 3.2.5 or greater and the GNU assembler, you must have a version modified after October 16th, 1995 in order for the GNU C compiler to build.  See the file README.RS6000 for more details on of these problems.

     GNU CC does not yet support the 64-bit PowerPC instructions.

     Objective C does not work on this architecture because it makes assumptions that are incompatible with the calling conventions.

     AIX on the RS/6000 provides support (NLS) for environments outside of the United States.  Compilers and assemblers use NLS to support locale-specific representations of various objects including floating-point numbers ("." vs "," for separating decimal fractions). There have been problems reported where the library linked with GNU CC does not produce the same floating-point formats that the assembler accepts.  If you have this problem, set the LANG environment variable to "C" or "En_US".

     Due to changes in the way that GNU CC invokes the binder (linker) for AIX 4.1, you may now receive warnings of duplicate symbols from the link step that were not reported before.  The assembly files generated by GNU CC for AIX have always included multiple symbol definitions for certain global variable and function declarations in the original program.  The warnings should not prevent the linker from producing a correct library or runnable executable.

     By default, AIX 4.1 produces code that can be used on either Power or PowerPC processors.

     You can specify a default version for the -mcpu=CPU_TYPE switch by using the configure option --with-cpu-CPU_TYPE.

powerpc-*-elf
powerpc-*-sysv4
     PowerPC system in big endian mode, running System V.4.

     You can specify a default version for the -mcpu=CPU_TYPE switch by using the configure option --with-cpu-CPU_TYPE.

powerpc-*-linux-gnu
     PowerPC system in big endian mode, running the Linux-based GNU system.

     You can specify a default version for the -mcpu=CPU_TYPE switch by using the configure option --with-cpu-CPU_TYPE.

powerpc-*-eabiaix
     Embedded PowerPC system in big endian mode with -mcall-aix selected as the default.

     You can specify a default version for the -mcpu=CPU_TYPE switch by using the configure option --with-cpu-CPU_TYPE.

powerpc-*-eabisim
     Embedded PowerPC system in big endian mode for use in running under the PSIM simulator.

     You can specify a default version for the -mcpu=CPU_TYPE switch by using the configure option --with-cpu-CPU_TYPE.

powerpc-*-eabi
     Embedded PowerPC system in big endian mode.

     You can specify a default version for the -mcpu=CPU_TYPE switch by using the configure option --with-cpu-CPU_TYPE.

powerpcle-*-elf
powerpcle-*-sysv4
     PowerPC system in little endian mode, running System V.4.

     You can specify a default version for the -mcpu=CPU_TYPE switch by using the configure option --with-cpu-CPU_TYPE.

powerpcle-*-solaris2*
     PowerPC system in little endian mode, running Solaris 2.5.1 or higher.

     You can specify a default version for the -mcpu=CPU_TYPE switch by using the configure option --with-cpu-CPU_TYPE. Beta versions of the Sun 4.0 compiler do not seem to be able to build GNU CC correctly.  There are also problems with the host assembler and linker that are fixed by using the GNU versions of these tools.

powerpcle-*-eabisim
     Embedded PowerPC system in little endian mode for use in running under the PSIM simulator.

powerpcle-*-eabi
     Embedded PowerPC system in little endian mode.

     You can specify a default version for the -mcpu=CPU_TYPE switch by using the configure option --with-cpu-CPU_TYPE.

powerpcle-*-winnt
powerpcle-*-pe
     PowerPC system in little endian mode running Windows NT.

     You can specify a default version for the -mcpu=CPU_TYPE switch by using the configure option --with-cpu-CPU_TYPE.

vax-dec-ultrix
     Don't try compiling with Vax C (vcc).  It produces incorrect code in some cases (for example, when alloca is used).

     Meanwhile, compiling cp/parse.c with pcc does not work because of an internal table size limitation in that compiler.  To avoid this problem, compile just the GNU C compiler first, and use it to recompile building all the languages that you want to run.

sparc-sun-*
     See Sun Install, for information on installing GNU CC on Sun systems.

vax-dec-vms
     See VMS Install, for details on how to install GNU CC on VMS.

we32k-*-*
     These computers are also known as the 3b2, 3b5, 3b20 and other similar names.  (However, the 3b1 is actually a 68000; see Configurations.)

     Don't use -g when compiling with the system's compiler.  The system's linker seems to be unable to handle such a large program with debugging information.

     The system's compiler runs out of capacity when compiling stmt.c in GNU CC.  You can work around this by building cpp in GNU CC first, then use that instead of the system's preprocessor with the system's C compiler to compile stmt.c.  Here is how:

          mv /lib/cpp /lib/cpp.att
          cp cpp /lib/cpp.gnu
          echo '/lib/cpp.gnu -traditional ${1+"$@"}' > /lib/cpp
          chmod +x /lib/cpp

     The system's compiler produces bad code for some of the GNU CC optimization files.  So you must build the stage 2 compiler without optimization.  Then build a stage 3 compiler with optimization. That executable should work.  Here are the necessary commands:

          make LANGUAGES=c CC=stage1/xgcc CFLAGS="-Bstage1/ -g"
          make stage2
          make CC=stage2/xgcc CFLAGS="-Bstage2/ -g -O"

     You may need to raise the ULIMIT setting to build a C++ compiler, as the file cc1plus is larger than one megabyte.

Compilation in a Separate Directory
===================================

If you wish to build the object files and executables in a directory other than the one containing the source files, here is what you must do differently:

 1. Make sure you have a version of Make that supports the VPATH feature.  (GNU Make supports it, as do Make versions on most BSD systems.)

 2. If you have ever run configure in the source directory, you must undo the configuration.  Do this by running:

          make distclean

 3. Go to the directory in which you want to build the compiler before running configure:

          mkdir gcc-sun3
          cd gcc-sun3

     On systems that do not support symbolic links, this directory must be on the same file system as the source code directory.

 4. Specify where to find configure when you run it:

          ../gcc/configure ...

     This also tells configure where to find the compiler sources; configure takes the directory from the file name that was used to invoke it.  But if you want to be sure, you can specify the source directory with the --srcdir option, like this:

          ../gcc/configure --srcdir=../gcc OTHER OPTIONS

     The directory you specify with --srcdir need not be the same as the one that configure is found in.

Now, you can run make in that directory.  You need not repeat the configuration steps shown above, when ordinary source files change.  You must, however, run configure again when the configuration files change, if your system does not support symbolic links.

Building and Installing a Cross-Compiler
========================================

GNU CC can function as a cross-compiler for many machines, but not all.

  * Cross-compilers for the Mips as target using the Mips assembler currently do not work, because the auxiliary programs mips-tdump.c and mips-tfile.c can't be compiled on anything but a Mips.  It does work to cross compile for a Mips if you use the GNU assembler and linker.

  * Cross-compilers between machines with different floating point formats have not all been made to work.  GNU CC now has a floating point emulator with which these can work, but each target machine description needs to be updated to take advantage of it.

  * Cross-compilation between machines of different word sizes is somewhat problematic and sometimes does not work.

Since GNU CC generates assembler code, you probably need a cross-assembler that GNU CC can run, in order to produce object files. If you want to link on other than the target machine, you need a cross-linker as well.  You also need header files and libraries suitable for the target machine that you can install on the host machine.

Steps of Cross-Compilation
--------------------------

To compile and run a program using a cross-compiler involves several steps:

  * Run the cross-compiler on the host machine to produce assembler files for the target machine.  This requires header files for the target machine.

  * Assemble the files produced by the cross-compiler.  You can do this either with an assembler on the target machine, or with a cross-assembler on the host machine.

  * Link those files to make an executable.  You can do this either with a linker on the target machine, or with a cross-linker on the host machine.  Whichever machine you use, you need libraries and certain startup files (typically crt....o) for the target machine.

It is most convenient to do all of these steps on the same host machine, since then you can do it all with a single invocation of GNU CC.  This requires a suitable cross-assembler and cross-linker.  For some targets, the GNU assembler and linker are available.

Configuring a Cross-Compiler
----------------------------

To build GNU CC as a cross-compiler, you start out by running configure.  Use the --target=TARGET to specify the target type.  If configure was unable to correctly identify the system you are running on, also specify the --build=BUILD option.  For example, here is how to configure for a cross-compiler that produces code for an HP 68030 system running BSD on a system that configure can correctly identify:

     ./configure --target=m68k-hp-bsd4.3

Tools and Libraries for a Cross-Compiler
----------------------------------------

If you have a cross-assembler and cross-linker available, you should install them now.  Put them in the directory /usr/local/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 GNU CC 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 and GAS.  Configure them with the same --host and --target options that you use for configuring GNU CC, then build and install them.  They install their executables automatically into the proper directory.  Alas, they do not support all the targets that GNU CC supports.

If you want to install libraries to use with the cross-compiler, such as a standard C library, put them in the directory /usr/local/TARGET/lib; installation of GNU CC copies all the files in that subdirectory into the proper place for GNU CC to find them and link with them.  Here's an example of copying some libraries from a target machine:

     ftp TARGET-MACHINE
     lcd /usr/local/TARGET/lib
     cd /lib
     get libc.a
     cd /usr/lib
     get libg.a
     get libm.a
     quit

The precise set of libraries you'll need, and their locations on the target machine, vary depending on its operating system.

Many targets require ``start files'' such as crt0.o and crtn.o which are linked into each executable; these too should be placed in /usr/local/TARGET/lib.  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. Here's an example of copying these files from a target machine:

     ftp TARGET-MACHINE
     lcd /usr/local/TARGET/lib
     prompt
     cd /lib
     mget *crt*.o
     cd /usr/lib
     mget *crt*.o
     quit

libgcc.a and Cross-Compilers
----------------------------

Code compiled by GNU CC uses certain runtime support functions implicitly.  Some of these functions can be compiled successfully with GNU CC itself, but a few cannot be.  These problem functions are in the source file libgcc1.c; the library made from them is called libgcc1.a.

When you build a native compiler, these functions are compiled with some other compiler--the one that you use for bootstrapping GNU CC. Presumably it knows how to open code these operations, or else knows how to call the run-time emulation facilities that the machine comes with. But this approach doesn't work for building a cross-compiler.  The compiler that you use for building knows about the host system, not the target system.

So, when you build a cross-compiler you have to supply a suitable library libgcc1.a that does the job it is expected to do.

To compile libgcc1.c with the cross-compiler itself does not work.  The functions in this file are supposed to implement arithmetic operations that GNU CC does not know how to open code for your target machine.  If these functions are compiled with GNU CC itself, they will compile into infinite recursion.

On any given target, most of these functions are not needed.  If GNU CC can open code an arithmetic operation, it will not call these functions to perform the operation.  It is possible that on your target machine, none of these functions is needed.  If so, you can supply an empty library as libgcc1.a.

Many targets need library support only for multiplication and division. If you are linking with a library that contains functions for multiplication and division, you can tell GNU CC to call them directly by defining the macros MULSI3_LIBCALL, and the like.  These macros need to be defined in the target description macro file.  For some targets, they are defined already.  This may be sufficient to avoid the need for libgcc1.a; if so, you can supply an empty library.

Some targets do not have floating point instructions; they need other functions in libgcc1.a, which do floating arithmetic. Recent versions of GNU CC have a file which emulates floating point. With a certain amount of work, you should be able to construct a floating point emulator that can be used as libgcc1.a.  Perhaps future versions will contain code to do this automatically and conveniently.  That depends on whether someone wants to implement it.

Some embedded targets come with all the necessary libgcc1.a routines written in C or assembler.  These targets build libgcc1.a automatically and you do not need to do anything special for them.  Other embedded targets do not need any libgcc1.a routines since all the necessary operations are supported by the hardware.

If your target system has another C compiler, you can configure GNU CC as a native compiler on that machine, build just libgcc1.a with make libgcc1.a on that machine, and use the resulting file with the cross-compiler.  To do this, execute the following on the target machine:

     cd TARGET-BUILD-DIR
     ./configure --host=sparc --target=sun3
     make libgcc1.a

And then this on the host machine:

     ftp TARGET-MACHINE
     binary
     cd TARGET-BUILD-DIR
     get libgcc1.a
     quit

Another way to provide the functions you need in libgcc1.a is to define the appropriate perform_... macros for those functions.  If these definitions do not use the C arithmetic operators that they are meant to implement, you should be able to compile them with the cross-compiler you are building.  (If these definitions already exist for your target file, then you are all set.)

To build libgcc1.a using the perform macros, use LIBGCC1=libgcc1.a OLDCC=./xgcc when building the compiler. Otherwise, you should place your replacement library under the name libgcc1.a in the directory in which you will build the cross-compiler, before you run make.

Cross-Compilers and Header Files
--------------------------------

If you are cross-compiling a standalone program or a program for an embedded system, then you may not need any header files except the few that are part of GNU CC (and those of your program).  However, if you intend to link your program with a standard C library such as libc.a, then you probably need to compile with the header files that go with the library you use.

The GNU C compiler does not come with these files, because (1) they are system-specific, and (2) they belong in a C library, not in a compiler.

If the GNU C library supports your target machine, then you can get the header files from there (assuming you actually use the GNU library when you link your program).

If your target machine comes with a C compiler, it probably comes with suitable header files also.  If you make these files accessible from the host machine, the cross-compiler can use them also.

Otherwise, you're on your own in finding header files to use when cross-compiling.

When you have found suitable header files, put them in the directory /usr/local/TARGET/include, before building the cross compiler.  Then installation will run fixincludes properly and install the corrected versions of the header files where the compiler will use them.

Provide the header files before you build the cross-compiler, because the build stage actually runs the cross-compiler to produce parts of libgcc.a.  (These are the parts that can be compiled with GNU CC.)  Some of them need suitable header files.

Here's an example showing how to copy the header files from a target machine.  On the target machine, do this:

     (cd /usr/include; tar cf - .) > tarfile

Then, on the host machine, do this:

     ftp TARGET-MACHINE
     lcd /usr/local/TARGET/include
     get tarfile
     quit
     tar xf tarfile

Actually Building the Cross-Compiler
------------------------------------

Now you can proceed just as for compiling a single-machine compiler through the step of building stage 1.  If you have not provided some sort of libgcc1.a, then compilation will give up at the point where it needs that file, printing a suitable error message.  If you do provide libgcc1.a, then building the compiler will automatically compile and link a test program called libgcc1-test; if you get errors in the linking, it means that not all of the necessary routines in libgcc1.a are available.

You must provide the header file float.h.  One way to do this is to compile enquire and run it on your target machine.  The job of enquire is to run on the target machine and figure out by experiment the nature of its floating point representation. enquire records its findings in the header file float.h. If you can't produce this file by running enquire on the target machine, then you will need to come up with a suitable float.h in some other way (or else, avoid using it in your programs).

Do not try to build stage 2 for a cross-compiler.  It doesn't work to rebuild GNU CC as a cross-compiler using the cross-compiler, because that would produce a program that runs on the target machine, not on the host.  For example, if you compile a 386-to-68030 cross-compiler with itself, the result will not be right either for the 386 (because it was compiled into 68030 code) or for the 68030 (because it was configured for a 386 as the host).  If you want to compile GNU CC into 68030 code, whether you compile it on a 68030 or with a cross-compiler on a 386, you must specify a 68030 as the host when you configure it.

To install the cross-compiler, use make install, as usual.

Installing GNU CC on the Sun
============================

On Solaris (version 2.1), do not use the linker or other tools in /usr/ucb to build GNU CC.  Use /usr/ccs/bin.

Make sure the environment variable FLOAT_OPTION is not set when you compile libgcc.a.  If this option were set to f68881 when libgcc.a is compiled, the resulting code would demand to be linked with a special startup file and would not link properly without special pains.

There is a bug in alloca in certain versions of the Sun library. To avoid this bug, install the binaries of GNU CC that were compiled by GNU CC.  They use alloca as a built-in function and never the one in the library.

Some versions of the Sun compiler crash when compiling GNU CC.  The problem is a segmentation fault in cpp.  This problem seems to be due to the bulk of data in the environment variables.  You may be able to avoid it by using the following command to compile GNU CC with Sun CC:

     make CC="TERMCAP=x OBJS=x LIBFUNCS=x STAGESTUFF=x cc"

SunOS 4.1.3 and 4.1.3_U1 have bugs that can cause intermittent core dumps when compiling GNU CC.  A common symptom is an internal compiler error which does not recur if you run it again. To fix the problem, install Sun recommended patch 100726 (for SunOS 4.1.3) or 101508 (for SunOS 4.1.3_U1), or upgrade to a later SunOS release.

Installing GNU CC on VMS
========================

The VMS version of GNU CC is distributed in a backup saveset containing both source code and precompiled binaries.

To install the gcc command so you can use the compiler easily, in the same manner as you use the VMS C compiler, you must install the VMS CLD file for GNU CC as follows:

 1. Define the VMS logical names GNU_CC and GNU_CC_INCLUDE to point to the directories where the GNU CC executables (gcc-cpp.exe, gcc-cc1.exe, etc.) and the C include files are kept respectively.  This should be done with the commands:

          $ assign /system /translation=concealed -
            disk:[gcc.] gnu_cc
          $ assign /system /translation=concealed -
            disk:[gcc.include.] gnu_cc_include

     with the appropriate disk and directory names.  These commands can be placed in your system startup file so they will be executed whenever the machine is rebooted.  You may, if you choose, do this via the GCC_INSTALL.COM script in the [GCC] directory.

 2. Install the GCC command with the command line:

          $ set command /table=sys$common:[syslib]dcltables -
            /output=sys$common:[syslib]dcltables gnu_cc:[000000]gcc
          $ install replace sys$common:[syslib]dcltables

 3. To install the help file, do the following:

          $ library/help sys$library:helplib.hlb gcc.hlp

     Now you can invoke the compiler with a command like gcc /verbose file.c, which is equivalent to the command gcc -v -c file.c in Unix.

If you wish to use GNU C++ you must first install GNU CC, and then perform the following steps:

 1. Define the VMS logical name GNU_GXX_INCLUDE to point to the directory where the preprocessor will search for the C++ header files. This can be done with the command:

          $ assign /system /translation=concealed -
            disk:[gcc.gxx_include.] gnu_gxx_include

     with the appropriate disk and directory name.  If you are going to be using libg++, this is where the libg++ install procedure will install the libg++ header files.

 2. Obtain the file gcc-cc1plus.exe, and place this in the same directory that gcc-cc1.exe is kept.

     The GNU C++ compiler can be invoked with a command like gcc /plus /verbose file.cc, which is equivalent to the command g++ -v -c file.cc in Unix.

We try to put corresponding binaries and sources on the VMS distribution tape.  But sometimes the binaries will be from an older version than the sources, because we don't always have time to update them.  (Use the /version option to determine the version number of the binaries and compare it with the source file version.c to tell whether this is so.)  In this case, you should use the binaries you get to recompile the sources.  If you must recompile, here is how:

 1. Execute the command procedure vmsconfig.com to set up the files tm.h, config.h, aux-output.c, and md., and to create files tconfig.h and hconfig.h.  This procedure also creates several linker option files used by make-cc1.com and a data file used by make-l2.com.

          $ @vmsconfig.com

 2. Setup the logical names and command tables as defined above.  In addition, define the VMS logical name GNU_BISON to point at the to the directories where the Bison executable is kept.  This should be done with the command:

          $ assign /system /translation=concealed -
            disk:[bison.] gnu_bison

     You may, if you choose, use the INSTALL_BISON.COM script in the [BISON] directory.

 3. Install the BISON command with the command line:

          $ set command /table=sys$common:[syslib]dcltables -
            /output=sys$common:[syslib]dcltables -
            gnu_bison:[000000]bison
          $ install replace sys$common:[syslib]dcltables

 4. Type @make-gcc to recompile everything (alternatively, submit the file make-gcc.com to a batch queue).  If you wish to build the GNU C++ compiler as well as the GNU CC compiler, you must first edit make-gcc.com and follow the instructions that appear in the comments.

 5. In order to use GCC, you need a library of functions which GCC compiled code will call to perform certain tasks, and these functions are defined in the file libgcc2.c.  To compile this you should use the command procedure make-l2.com, which will generate the library libgcc2.olb. libgcc2.olb should be built using the compiler built from the same distribution that libgcc2.c came from, and make-gcc.com will automatically do all of this for you.

     To install the library, use the following commands:

          $ library gnu_cc:[000000]gcclib/delete=(new,eprintf)
          $ library gnu_cc:[000000]gcclib/delete=L_*
          $ library libgcc2/extract=*/output=libgcc2.obj
          $ library gnu_cc:[000000]gcclib libgcc2.obj

     The first command simply removes old modules that will be replaced with modules from libgcc2 under different module names.  The modules new and eprintf may not actually be present in your gcclib.olb---if the VMS librarian complains about those modules not being present, simply ignore the message and continue on with the next command.  The second command removes the modules that came from the previous version of the library libgcc2.c.

     Whenever you update the compiler on your system, you should also update the library with the above procedure.

 6. You may wish to build GCC in such a way that no files are written to the directory where the source files reside.  An example would be the when the source files are on a read-only disk.  In these cases, execute the following DCL commands (substituting your actual path names):

          $ assign dua0:[gcc.build_dir.]/translation=concealed, -
                   dua1:[gcc.source_dir.]/translation=concealed  gcc_build
          $ set default gcc_build:[000000]

     where the directory dua1:[gcc.source_dir] contains the source code, and the directory dua0:[gcc.build_dir] is meant to contain all of the generated object files and executables.  Once you have done this, you can proceed building GCC as described above.  (Keep in mind that gcc_build is a rooted logical name, and thus the device names in each element of the search list must be an actual physical device name rather than another rooted logical name).

 7. If you are building GNU CC with a previous version of GNU CC, you also should check to see that you have the newest version of the assembler.  In particular, GNU CC version 2 treats global constant variables slightly differently from GNU CC version 1, and GAS version 1.38.1 does not have the patches required to work with GCC version 2. If you use GAS 1.38.1, then extern const variables will not have the read-only bit set, and the linker will generate warning messages about mismatched psect attributes for these variables.  These warning messages are merely a nuisance, and can safely be ignored.

     If you are compiling with a version of GNU CC older than 1.33, specify /DEFINE=("inline=") as an option in all the compilations.  This requires editing all the gcc commands in make-cc1.com. (The older versions had problems supporting inline.)  Once you have a working 1.33 or newer GNU CC, you can change this file back.

 8. If you want to build GNU CC with the VAX C compiler, you will need to make minor changes in make-cccp.com and make-cc1.com to choose alternate definitions of CC, CFLAGS, and LIBS.  See comments in those files.  However, you must also have a working version of the GNU assembler (GNU as, aka GAS) as it is used as the back-end for GNU CC to produce binary object modules and is not included in the GNU CC sources.  GAS is also needed to compile libgcc2 in order to build gcclib (see above); make-l2.com expects to be able to find it operational in gnu_cc:[000000]gnu-as.exe.

     To use GNU CC on VMS, you need the VMS driver programs gcc.exe, gcc.com, and gcc.cld.  They are distributed with the VMS binaries (gcc-vms) rather than the GNU CC sources.  GAS is also included in gcc-vms, as is Bison.

     Once you have successfully built GNU CC with VAX C, you should use the resulting compiler to rebuild itself.  Before doing this, be sure to restore the CC, CFLAGS, and LIBS definitions in make-cccp.com and make-cc1.com.  The second generation compiler will be able to take advantage of many optimizations that must be suppressed when building with other compilers.

Under previous versions of GNU CC, the generated code would occasionally give strange results when linked with the sharable VAXCRTL library. Now this should work.

Even with this version, however, GNU CC itself should not be linked with the sharable VAXCRTL.  The version of qsort in VAXCRTL has a bug (known to be present in VMS versions V4.6 through V5.5) which causes the compiler to fail.

The executables are generated by make-cc1.com and make-cccp.com use the object library version of VAXCRTL in order to make use of the qsort routine in gcclib.olb.  If you wish to link the compiler executables with the shareable image version of VAXCRTL, you should edit the file tm.h (created by vmsconfig.com) to define the macro QSORT_WORKAROUND.

QSORT_WORKAROUND is always defined when GNU CC is compiled with VAX C, to avoid a problem in case gcclib.olb is not yet available.

collect2
========

Many target systems do not have support in the assembler and linker for ``constructors''---initialization functions to be called before the official ``start'' of main.  On such systems, GNU CC uses a utility called collect2 to arrange to call these functions at start time.

The program collect2 works by linking the program once and looking through the linker output file for symbols with particular names indicating they are constructor functions.  If it finds any, it creates a new temporary .c file containing a table of them, compiles it, and links the program a second time including that file.

The actual calls to the constructors are carried out by a subroutine called __main, which is called (automatically) at the beginning of the body of main (provided main was compiled with GNU CC).  Calling __main is necessary, even when compiling C code, to allow linking C and C++ object code together.  (If you use -nostdlib, you get an unresolved reference to __main, since it's defined in the standard GCC library.  Include -lgcc at the end of your compiler command line to resolve this reference.)

The program collect2 is installed as ld in the directory where the passes of the compiler are installed.  When collect2 needs to find the real ld, it tries the following file names:

  * real-ld in the directories listed in the compiler's search directories.

  * real-ld in the directories listed in the environment variable PATH.

  * The file specified in the REAL_LD_FILE_NAME configuration macro, if specified.

  * ld in the compiler's search directories, except that collect2 will not execute itself recursively.

  * ld in PATH.

``The compiler's search directories'' means all the directories where gcc searches for passes of the compiler.  This includes directories that you specify with -B.

Cross-compilers search a little differently:

  * real-ld in the compiler's search directories.

  * TARGET-real-ld in PATH.

  * The file specified in the REAL_LD_FILE_NAME configuration macro, if specified.

  * ld in the compiler's search directories.

  * TARGET-ld in PATH.

collect2 explicitly avoids running ld using the file name under which collect2 itself was invoked.  In fact, it remembers up a list of such names---in case one copy of collect2 finds another copy (or version) of collect2 installed as ld in a second place in the search path.

collect2 searches for the utilities nm and strip using the same algorithm as above for ld.

Standard Header File Directories
================================

GCC_INCLUDE_DIR means the same thing for native and cross.  It is where GNU CC stores its private include files, and also where GNU CC stores the fixed include files.  A cross compiled GNU CC runs fixincludes on the header files in $(tooldir)/include. (If the cross compilation header files need to be fixed, they must be installed before GNU CC is built.  If the cross compilation header files are already suitable for ANSI C and GNU CC, nothing special need be done).

GPLUS_INCLUDE_DIR means the same thing for native and cross.  It is where g++ looks first for header files.  libg++ installs only target independent header files in that directory.

LOCAL_INCLUDE_DIR is used only for a native compiler.  It is normally /usr/local/include.  GNU CC searches this directory so that users can install header files in /usr/local/include.

CROSS_INCLUDE_DIR is used only for a cross compiler.  GNU CC doesn't install anything there.

TOOL_INCLUDE_DIR is used for both native and cross compilers.  It is the place for other packages to install header files that GNU CC will use.  For a cross-compiler, this is the equivalent of /usr/include.  When you build a cross-compiler, fixincludes processes any header files in this directory.