# Prerequisites for GCC

GCC requires that various tools and packages be available for use in the build procedure. Modifying GCC sources requires additional tools described below.

### Tools/packages necessary for building GCC

ISO C90 compiler
  Necessary to bootstrap GCC, although versions of GCC prior to 3.4 also allow bootstrapping with a traditional (K&R) C compiler.

  To build all languages in a cross-compiler or other configuration where 3-stage bootstrap is not performed, you need to start with an existing GCC binary (version 2.95 or later) because source code for language frontends other than C might use GCC extensions.

GNAT
  In order to build the Ada compiler (GNAT) you must already have GNAT installed because portions of the Ada frontend are written in Ada (with GNAT extensions.) Refer to the Ada installation instructions for more specific information.
A “working” POSIX compatible shell, or GNU bash
  Necessary when running configure because some /bin/sh shells have bugs and may crash when configuring the target libraries. In other cases, /bin/sh or ksh have disastrous corner-case performance problems. This can cause target configure runs to literally take days to complete in some cases.

  So on some platforms /bin/ksh is sufficient, on others it isn't. See the host/target specific instructions for your platform, or use bash to be sure. Then set CONFIG_SHELL in your environment to your “good” shell prior to running configure/make.

  zsh is not a fully compliant POSIX shell and will not work when configuring GCC.

A POSIX or SVR4 awk
  Necessary for creating some of the generated source files for GCC. If in doubt, use a recent GNU awk version, as some of the older ones are broken. GNU awk version 3.1.5 is known to work.
GNU binutils
  Necessary in some circumstances, optional in others. See the host/target specific instructions for your platform for the exact requirements.
gzip version 1.2.4 (or later) or
bzip2 version 1.0.2 (or later)
  Necessary to uncompress GCC tar files when source code is obtained via FTP mirror sites.
GNU make version 3.79.1 (or later)
  You must have GNU make installed to build GCC.
GNU tar version 1.14 (or later)
  Necessary (only on some platforms) to untar the source code. Many systems' tar programs will also work, only try GNU tar if you have problems.
GNU Multiple Precision Library (GMP) version 4.1 (or later)
  Necessary to build GCC. If you do not have it installed in your library search path, you will have to configure with the --with-gmp configure option. See also --with-gmp-lib and --with-gmp-include.
MPFR Library version 2.3.0 (or later)
  Necessary to build GCC. It can be downloaded from http://www.mpfr.org/. The version of MPFR that is bundled with GMP 4.1.x contains numerous bugs. Although GCC may appear to function with the buggy versions of MPFR, there are a few bugs that will not be fixed when using this version. It is strongly recommended to upgrade to the recommended version of MPFR.

  The --with-mpfr configure option should be used if your MPFR Library is not installed in your default library search path. See also --with-mpfr-lib and --with-mpfr-include.

jar, or InfoZIP (zip and unzip)
  Necessary to build libgcj, the GCJ runtime.

### Tools/packages necessary for modifying GCC

autoconf version 2.59
GNU m4 version 1.4 (or later)
  Necessary when modifying configure.ac, aclocal.m4, etc. to regenerate configure and config.in files.
automake version 1.9.6
  Necessary when modifying a Makefile.am file to regenerate its associated Makefile.in.

  Much of GCC does not use automake, so directly edit the Makefile.in file. Specifically this applies to the gcc, intl, libcpp, libiberty, libobjc directories as well as any of their subdirectories.

  For directories that use automake, GCC requires the latest release in the 1.9.x series, which is currently 1.9.6. When regenerating a directory to a newer version, please update all the directories using an older 1.9.x to the latest released version.

gettext version 0.14.5 (or later)
  Needed to regenerate gcc.pot.
gperf version 2.7.2 (or later)
  Necessary when modifying gperf input files, e.g. gcc/cp/cfns.gperf to regenerate its associated header file, e.g. gcc/cp/cfns.h.
DejaGnu 1.4.4
Expect
Tcl
  Necessary to run the GCC testsuite; see the section on testing for details.
autogen version 5.5.4 (or later) and
guile version 1.4.1 (or later)
  Necessary to regenerate fixinc/fixincl.x from fixinc/inclhack.def and fixinc/*.tpl.

  Necessary to run make check for fixinc.

  Necessary to regenerate the top level Makefile.in file from Makefile.tpl and Makefile.def.

GNU Bison version 1.28 (or later)
  Necessary when modifying *.y files. Necessary to build the `treelang` front end (which is not enabled by default) from a checkout of the SVN repository; the generated files are not in the repository. They are included in releases.

  Berkeley yacc (byacc) has been reported to work as well.

Flex version 2.5.4 (or later)
  Necessary when modifying *.l files.

  Necessary to build GCC during development because the generated output files are not included in the SVN repository. They are included in releases.

Texinfo version 4.4 (or later)
  Necessary for running makeinfo when modifying *.texi files to test your changes.

  Necessary for running make dvi or make pdf to create printable documentation in DVI or PDF format. Texinfo version 4.8 or later is required for make pdf.

  Necessary to build GCC documentation during development because the generated output files are not included in the SVN repository. They are included in releases.

TeX (any working version)
  Necessary for running texi2dvi and texi2pdf, which are used when running make dvi or make pdf to create DVI or PDF files, respectively.
SVN (any version)
SSH (any version)
  Necessary to access the SVN repository. Public releases and weekly snapshots of the development sources are also available via FTP.
Perl version 5.6.1 (or later)
  Necessary when regenerating Makefile dependencies in libiberty. Necessary when regenerating libiberty/functions.texi. Necessary when generating manpages from Texinfo manuals. Necessary when targetting Darwin, building libstdc++, and not using --disable-symvers. Used by various scripts to generate some files included in SVN (mainly Unicode-related and rarely changing) from source tables.
GNU diffutils version 2.7 (or later)
  Useful when submitting patches for the GCC source code.
patch version 2.5.4 (or later)
  Necessary when applying patches, created with diff, to one's own sources.
ecj1
gjavah
  If you wish to modify .java files in libjava, you will need to configure with --enable-java-maintainer-mode, and you will need to have executables named ecj1 and gjavah in your path. The ecj1 executable should run the Eclipse Java compiler via the GCC-specific entry point. You can download a suitable jar from ftp://sourceware.org/pub/java/, or by running the script contrib/download_ecj.

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