     Using newer version of GCC and binutils with the FreeBSD Ports
                               Collection

  Martin Matuska

   <mm@FreeBSD.org>

   Copyright (c) 2009 The FreeBSD Documentation Project

   $FreeBSD: doc/en_US.ISO8859-1/articles/custom-gcc/article.sgml,v
   1.2 2009/09/04 14:22:47 danger Exp $

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   Many of the designations used by manufacturers and sellers to
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   by the "(TM)" or the "(R)" symbol.

   This article describes how to use newer versions of the GCC
   compilers and binutils from the FreeBSD ports tree. Custom GCC
   configurations are also discussed.

     --------------------------------------------------------------

1 Introduction

   The default system compiler as of FreeBSD 8.0 is GCC version
   4.2.1. In addition, the base system of FreeBSD includes binutils
   version 2.15. These versions are several years old and lack, among
   other things, support for recent CPU instructions like SSSE3,
   SSE4.1, SSE4.2, etc. Due to licensing issues, new versions of
   these applications will not be integrated into the base system.
   Luckily, it is possible to use a newer version of the GCC compiler
   (e.g. version 4.4) with the help of the FreeBSD ports tree.

     --------------------------------------------------------------

2 Prerequisites

  2.1 Installing binutils from ports

   To make use of all of the new features in the latest GCC versions,
   the latest version of binutils needs to be installed. Installation
   of the newer version of binutils is optional; but without it,
   there will be no support for new CPU instructions.

   To install the latest available version of binutils using the
   FreeBSD ports tree, issue the following command:

 # cd /usr/ports/devel/binutils && make install

     --------------------------------------------------------------

  2.2 Installing GCC from ports

   The FreeBSD ports tree offers several new versions of GCC. The
   following example is for the stable version 4.4. However, it is
   possible to install previous or later development versions (e.g.
   lang/gcc43 or lang/gcc45).

   To install one of the mentioned GCC ports, run the following
   command:

 # cd /usr/ports/lang/gcc44 && make install

     --------------------------------------------------------------

3 Configuring ports for custom version of GCC

   Additional system configuration is required in order to use custom
   version of GCC installed from the FreeBSD ports tree.

   

     --------------------------------------------------------------

  3.1 Adjusting make.conf

   Add the following lines to the /etc/make.conf file (or modify
   appropriately):

 .if !empty(.CURDIR:M/usr/ports/*) && exists(/usr/local/bin/gcc44)
 CC=gcc44
 CXX=g++44
 CPP=cpp44
 .endif

   Alternatively, it is possible to specify the ${CC} and ${CPP}
   variables manually.

     Note: The examples above are for GCC version 4.4. To use gcc43,
     replace "gcc44" with "gcc43" and "4.4" with "4.3" and so on.

     --------------------------------------------------------------

  3.2 Adjusting libmap.conf

   Many of the ports' binaries and libraries link to libgcc_s or
   libstdc++. The base system already includes these libraries, but
   from an earlier version of GCC (version 4.2.1). To supply rtld
   (and ldd) with correct versions, add the following lines to the
   /etc/libmap.conf file (or modify appropriately):

 libgcc_s.so.1   gcc44/libgcc_s.so.1
 libgomp.so.1    gcc44/libgomp.so.1
 libobjc.so.3    gcc44/libobjc.so.2
 libssp.so.0     gcc44/libssp.so.0
 libstdc++.so.6  gcc44/libstdc++.so.6

     Note: The examples above are for GCC version 4.4. To use gcc43,
     replace "gcc44" with "gcc43" and so on. Note also that all of
     these libraries are fully backwards compatible with base system
     libraries.

     Warning: Some C++ programs may refuse to work if these libraries
     are not mapped correctly. If it is not feasible to map them all,
     it is recommended to map at least libstdc++.so.

     --------------------------------------------------------------

  3.3 Custom CFLAGS for the ports tree

   To add custom CFLAGS for the ports tree which are unsupported by
   the base system, adjust the /etc/make.conf according to the
   following example:

 .if !empty(.CURDIR:M/usr/ports/*) && exists(/usr/local/bin/gcc44)
 CC=gcc44
 CXX=g++44
 CPP=cpp44
 CFLAGS+=-mssse3
 .endif

   It is possible to completely replace CFLAGS and/or define custom
   CPUTYPE as well. We recommend setting CPUTYPE because many ports
   decide their optimizations flags based on this variable.

     --------------------------------------------------------------

  3.4 Excluding ports that do not build with new version of GCC

   To exclude ports that have problems with custom version of GCC,
   adjust the /etc/make.conf according to the following example:

 .if !empty(.CURDIR:M/usr/ports/*) && exists(/usr/local/bin/gcc44)
 .if empty(.CURDIR:M/usr/ports/net/openldap*)
 CC=gcc44
 CXX=g++44
 CPP=cpp44
 .endif
 .endif

   The example above excludes the forced use of gcc 4.4 for the
   net/openldap* ports. It is also possible to specify more ports on
   a single line:

 .if empty(.CURDIR:M/usr/ports/net/openldap*) && empty(.CURDIR:M/usr/ports/xxx/yyy) && ...

     --------------------------------------------------------------

4 Impact on the binary performance

   Using GCC version 4.4 with SSSE3 instruction set enabled (if
   supported by the CPU) may yield up to 10% average increase in
   binary performance. In certain tests, the results show more than a
   20% performance boost (e.g. in multimedia processing).

   The table located at
   http://people.freebsd.org/~mm/benchmarks/perlbench/ shows a
   comparison of GCC versions currently available in base FreeBSD
   system, GCC version 4.3 and GCC version 4.4 with various
   combinations of CFLAGS using the perlbench benchmark suite.

     --------------------------------------------------------------

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