lfs-book-zh_CN/chapter06/gcc.xml

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<sect1 id="ch-system-gcc" role="wrap">
<title>GCC-&gcc-version;</title>
<?dbhtml filename="gcc.html"?>

<indexterm zone="ch-system-gcc"><primary sortas="a-GCC">GCC</primary></indexterm>

<sect2 role="package"><title/>
<para>The GCC package contains the GNU compiler collection, which includes
the C and C++ compilers.</para>

<segmentedlist>
<segtitle>&buildtime;</segtitle>
<segtitle>&diskspace;</segtitle>
<seglistitem><seg>11.7 SBU</seg><seg>451 MB</seg></seglistitem>
</segmentedlist>

<segmentedlist>
<segtitle>&dependencies;</segtitle>
<seglistitem><seg>Bash, Binutils, Coreutils, Diffutils, Findutils,
Gawk, Gettext, Glibc, Grep, Make, Perl, Sed, and Texinfo</seg></seglistitem>
</segmentedlist>
</sect2>

<sect2 role="installation">
<title>Installation of GCC</title>

<para>This package is known to have issues when its default
optimization flags (including the <parameter>-march</parameter> and
<parameter>-mcpu</parameter> options) are changed. If any environment
variables that override default optimizations have been defined, such
as <envar>CFLAGS</envar> and <envar>CXXFLAGS</envar>,
unset them when building GCC.</para>

<para>Apply a <command>sed</command> substitution that will suppress the
installation of <filename class="libraryfile">libiberty.a</filename>. The
version of <filename class="libraryfile">libiberty.a</filename> provided by
Binutils will be used instead:</para>

<screen><userinput>sed -i 's/install_to_$(INSTALL_DEST) //' libiberty/Makefile.in</userinput></screen>

<para>The bootstrap build performed in <xref linkend="ch-tools-gcc-pass1"/>
built GCC with the <option>-fomit-frame-pointer</option> compiler flag.
Non-bootstrap builds omit this flag by default, so apply the following
<command>sed</command> to use it in order to ensure consistent compiler builds.
</para>

<screen><userinput>sed -i 's/^XCFLAGS =$/&amp; -fomit-frame-pointer/' gcc/Makefile.in</userinput></screen>

<para>The GCC documentation recommends building GCC outside of the source
directory in a dedicated build directory:</para>

<screen><userinput>mkdir ../gcc-build
cd ../gcc-build</userinput></screen>

<para>Prepare GCC for compilation:</para>

<screen><userinput>../gcc-&gcc-version;/configure --prefix=/usr \
    --libexecdir=/usr/lib --enable-shared \
    --enable-threads=posix --enable-__cxa_atexit \
    --enable-clocale=gnu --enable-languages=c,c++</userinput></screen>

<para>Compile the package:</para>

<screen><userinput>make</userinput></screen>

<important><para>In this section, the test suite for GCC is considered
critical. Do not skip it under any circumstance.</para></important>

<para>Test the results, but do not stop at errors:</para>

<screen><userinput>make -k check</userinput></screen>

<para>Some of the errors are known issues and were noted in the
previous chapter. The test suite notes from <xref
linkend="ch-tools-gcc-pass2" role=","/> are still relevant here. Be sure to
refer back to them as necessary.</para>

<para>Install the package:</para>

<screen><userinput>make install</userinput></screen>

<para>Some packages expect the C preprocessor to be installed in the
<filename class="directory">/lib</filename> directory.
To support those packages, create this symlink:</para>

<screen><userinput>ln -s ../usr/bin/cpp /lib</userinput></screen>

<para>Many packages use the name <command>cc</command> to call the C
compiler. To satisfy those packages, create a symlink:</para>

<screen><userinput>ln -s gcc /usr/bin/cc</userinput></screen>

<note><para>At this point, it is strongly recommended to repeat the
sanity check performed earlier in this chapter. Refer back to <xref
linkend="ch-system-readjusting" role=","/> and repeat the check. If the results
are in error, then the most likely reason is that the GCC Specs patch
from <xref linkend="chapter-temporary-tools"/> was erroneously applied
here.</para></note>

</sect2>


<sect2 id="contents-gcc" role="content"><title>Contents of GCC</title>

<segmentedlist>
<segtitle>Installed programs</segtitle>
<segtitle>Installed libraries</segtitle>
<seglistitem><seg>c++, cc (link to gcc), cpp, g++, gcc, gccbug, and
gcov</seg>
<seg>libgcc.a, libgcc_eh.a, libgcc_s.so, libstdc++.[a,so], and libsupc++.a</seg></seglistitem>
</segmentedlist>

<variablelist><bridgehead renderas="sect3">Short Descriptions</bridgehead>
<?dbfo list-presentation="list"?>
<?dbhtml list-presentation="table"?>

<varlistentry id="cc">
<term><command>cc</command></term>
<listitem>
<para>The C compiler</para>
<indexterm zone="ch-system-gcc cc"><primary sortas="b-cc">cc</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="cpp">
<term><command>cpp</command></term>
<listitem>
<para>The C preprocessor; it is used by the compiler to expand the
#include, #define, and similar statements in the source files</para>
<indexterm zone="ch-system-gcc cpp"><primary sortas="b-cpp">cpp</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="c">
<term><command>c++</command></term>
<listitem>
<para>The C++ compiler</para>
<indexterm zone="ch-system-gcc c"><primary sortas="b-c++">c++</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="g">
<term><command>g++</command></term>
<listitem>
<para>The C++ compiler</para>
<indexterm zone="ch-system-gcc g"><primary sortas="b-g++">g++</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="gcc">
<term><command>gcc</command></term>
<listitem>
<para>The C compiler</para>
<indexterm zone="ch-system-gcc gcc"><primary sortas="b-gcc">gcc</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="gccbug">
<term><command>gccbug</command></term>
<listitem>
<para>A shell script used to help create useful bug reports</para>
<indexterm zone="ch-system-gcc gccbug"><primary sortas="b-gccbug">gccbug</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="gcov">
<term><command>gcov</command></term>
<listitem>
<para>A coverage testing tool; it is used to analyze programs to
determine where optimizations will have the most effect</para>
<indexterm zone="ch-system-gcc gcov"><primary sortas="b-gcov">gcov</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="libgcc">
<term><filename class="libraryfile">libgcc</filename></term>
<listitem>
<para>Contains run-time support for <command>gcc</command></para>
<indexterm zone="ch-system-gcc libgcc"><primary sortas="c-libgcc*">libgcc*</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="libstdc">
<term><filename class="libraryfile">libstdc++</filename></term>
<listitem>
<para>The standard C++ library</para>
<indexterm zone="ch-system-gcc libstdc"><primary sortas="c-libstdc++">libstdc++</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="libsupc">
<term><filename class="libraryfile">libsupc++</filename></term>
<listitem>
<para>Provides supporting routines for the C++ programming language</para>
<indexterm zone="ch-system-gcc libsupc"><primary sortas="c-libsupc++">libsupc++</primary></indexterm>
</listitem>
</varlistentry>
</variablelist>

</sect2>

</sect1>