lfs-book/chapter06/gcc.xml

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<sect1 id="ch-system-gcc" role="wrap">
  <?dbhtml filename="gcc.html"?>

  <sect1info condition="script">
    <productname>gcc</productname>
    <productnumber>&gcc-version;</productnumber>
    <address>&gcc-url;</address>
  </sect1info>

  <title>GCC-&gcc-version;</title>

  <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>&gcc-ch6-sbu;</seg>
        <seg>&gcc-ch6-du;</seg>
      </seglistitem>
    </segmentedlist>

  </sect2>

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

    <para>First fix a problem identified upstream that causes some 
    programs to fail:</para>

<screen><userinput remap="pre">patch -Np1 -i ../&gcc-upstream-patch;</userinput></screen>
<!--
    <para>As in <xref linkend="ch-tools-gcc-pass2"/>, apply the following
    <command>sed</command> to force the build to use the
    <option>-fomit-frame-pointer</option> compiler flag in order to ensure
    consistent compiler builds:</para>

<screen><userinput remap="pre">case `uname -m` in
  i?86) sed -i 's/^T_CFLAGS =$/&amp; -fomit-frame-pointer/' gcc/Makefile.in ;;
esac</userinput></screen>
-->
    <para>The GCC documentation recommends building GCC outside of the source
    directory in a dedicated build directory:</para>

<screen><userinput remap="pre">mkdir -v ../gcc-build
cd ../gcc-build</userinput></screen>

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

<screen><userinput remap="configure">SED=sed                          \
../gcc-&gcc-version;/configure           \
     --prefix=/usr               \
     --enable-shared             \
     --enable-threads=posix      \
     --enable-__cxa_atexit       \
     --enable-clocale=gnu        \
     --enable-languages=c,c++    \
     --disable-multilib          \
     --disable-bootstrap         \
     --with-system-zlib</userinput></screen>

    <para>Note that for other languages, there are some prerequisites that
    are not available. See the BLFS Book for instructions on how to
    build all the GCC supported languages.</para>

    <variablelist>
      <title>The meaning of the new configure option:</title>

      <varlistentry>
        <term><envar>SED=sed</envar></term>
        <listitem>
          <para>Setting this environment variable prevents a hard-coded
          path to /tools/bin/sed.</para>
        </listitem>
      </varlistentry>
 
      <varlistentry>
        <term><parameter>--with-system-zlib</parameter></term>
        <listitem>
          <para>This switch tells GCC to link to the system installed copy of
          the Zlib library, rather than its own internal copy.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>Compile the package:</para>

<screen><userinput remap="make">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>One set of tests in the GCC test suite is known to exhaust the stack,
   so increase the stack size prior to running the tests:</para>

<screen><userinput remap="test">ulimit -s 32768</userinput></screen>

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

<screen><userinput remap="test">make -k check</userinput></screen>

    <para>To receive a summary of the test suite results, run:</para>

<screen><userinput remap="test">../gcc-&gcc-version;/contrib/test_summary</userinput></screen>

    <para>For only the summaries, pipe the output through
    <userinput>grep -A7 Summ</userinput>.</para>

    <para>Results can be compared with those located at <ulink
    url="&test-results;"/> and <ulink url="http://gcc.gnu.org/ml/gcc-testresults/"/>.</para>

    <para>A few unexpected failures cannot always be avoided. The GCC developers
    are usually aware of these issues, but have not resolved them yet. In
    particular, the <filename class="libraryfile">libmudflap</filename> tests
    are known to be particularly problematic as a result of a bug in GCC
    (<ulink url="http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20003"/>).
    Unless the test results are vastly different from those at the above URL,
    it is safe to continue.</para>

    <para>Install the package:</para>

<screen><userinput remap="install">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 remap="install">ln -sv ../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 remap="install">ln -sv gcc /usr/bin/cc</userinput></screen>

    <para>Add a compatibility symlink to enable building programs with
    Link Time Optimization (LTO):</para> 

<screen><userinput remap="install">install -dm755 /usr/lib/bfd-plugins
pushd /usr/lib/bfd-plugins

if [ $(uname -m) == "i686" ]; then 
   ln -sfv ../../libexec/gcc/i686-pc-linux-gnu/&gcc-version;/liblto_plugin.so 
else
   ln -sfv ../../libexec/gcc/x86_64-unknown-linux-gnu/&gcc-version;/liblto_plugin.so 
fi

popd</userinput></screen>

    <para>Now that our final toolchain is in place, it is important to again ensure
    that compiling and linking will work as expected. We do this by performing
    the same sanity checks as we did earlier in the chapter:</para>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='a'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='b'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='c'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='d'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='e'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='f'])"/>

<screen><computeroutput>/usr/lib/gcc/i686-pc-linux-gnu/&gcc-version;/../../../crt1.o succeeded
/usr/lib/gcc/i686-pc-linux-gnu/&gcc-version;/../../../crti.o succeeded
/usr/lib/gcc/i686-pc-linux-gnu/&gcc-version;/../../../crtn.o succeeded</computeroutput></screen>

  <para>Depending on your machine architecture, the above may differ slightly,
  the difference usually being the name of the directory
  after <filename class="directory">/usr/lib/gcc</filename>. If your machine is
  a 64-bit system, you may also see a directory named <filename class="directory">lib64</filename>
  towards the end of the string. The important thing to
  look for here is that <command>gcc</command> has found all three
  <filename>crt*.o</filename> files under the
  <filename class="directory">/usr/lib</filename> directory.</para>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='g'])"/>

<screen><userinput>grep -B4 '^ /usr/include' dummy.log</userinput></screen>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='h'])"/>

<screen><computeroutput>#include &lt;...&gt; search starts here:
 /usr/lib/gcc/i686-pc-linux-gnu/&gcc-version;/include
 /usr/local/include
 /usr/lib/gcc/i686-pc-linux-gnu/&gcc-version;/include-fixed
 /usr/include</computeroutput></screen>

   <para>Again, note that the directory named after your target triplet may be
   different than the above, depending on your architecture.</para>

    <note><para>As of version 4.3.0, GCC now unconditionally installs the
    <filename>limits.h</filename> file into the private
    <filename class="directory">include-fixed</filename> directory, and that
    directory is required to be in place.</para></note>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='i'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='j'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='k'])"/>

<screen><computeroutput>SEARCH_DIR("/usr/i686-pc-linux-gnu/lib32")
SEARCH_DIR("/usr/local/lib32")
SEARCH_DIR("/lib32")
SEARCH_DIR("/usr/lib32")
SEARCH_DIR("/usr/i686-pc-linux-gnu/lib")
SEARCH_DIR("/usr/local/lib")
SEARCH_DIR("/lib")
SEARCH_DIR("/usr/lib");</computeroutput></screen>

   <para>A 64-bit system may see a few different directories. For example, here
   is the output from an x86_64 machine:</para>

<screen><computeroutput>SEARCH_DIR("/usr/x86_64-unknown-linux-gnu/lib64")
SEARCH_DIR("/usr/local/lib64")
SEARCH_DIR("/lib64")
SEARCH_DIR("/usr/lib64")
SEARCH_DIR("/usr/x86_64-unknown-linux-gnu/lib")
SEARCH_DIR("/usr/local/lib")
SEARCH_DIR("/lib")
SEARCH_DIR("/usr/lib");</computeroutput></screen>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='l'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='m'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='n'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='o'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='p'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='q'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='r'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='s'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='t'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='u'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
    href="adjusting.xml"
    xpointer="xpointer(//*[@os='v'])"/>

    <para>Finally, move a misplaced file:</para>

<screen><userinput remap="install">mkdir -pv /usr/share/gdb/auto-load/usr/lib
mv -v /usr/lib/*gdb.py /usr/share/gdb/auto-load/usr/lib</userinput></screen>

  </sect2>

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

    <segmentedlist>
      <segtitle>Installed programs</segtitle>
      <segtitle>Installed libraries</segtitle>
      <segtitle>Installed directories</segtitle>

      <seglistitem>
        <seg>c++, cc (link to gcc), cpp, g++, gcc,
        gcc-ar, gcc-nm, gcc-ranlib, and gcov</seg>

        <seg>libasan.{a,so}, libatomic.{a,so}, libgcc.a, libgcc_eh.a, 
        libgcc_s.so, libgcov.a, libgomp.{a,so}, libiberty.a, libitm.{a,so},
        liblto_plugin.so, libmudflap.{a,so}, libmudflapth.{a,so},
        libquadmath.{a,so}, libssp.{a,so},
        libssp_nonshared.a, libstdc++.{a,so}, libsupc++.a and libtsan.{a,so}</seg>

        <seg>/usr/include/c++, /usr/lib/gcc, /usr/libexec/gcc, 
        /usr/share/gcc-&gcc-version;</seg>
      </seglistitem>
    </segmentedlist>

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

      <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="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="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="gcc-ar">
        <term><command>gcc-ar</command></term>
        <listitem>
          <para>A wrapper around <command>ar</command> that adds a
          plugin to the command line.  This program is only used
          to add "link time optization" and is not useful with the
          default build options.</para>
          <indexterm zone="ch-system-gcc gcc-ar">
            <primary sortas="b-gcc-ar">gc-ar</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="gcc-nm">
        <term><command>gcc-nm</command></term>
        <listitem>
          <para>A wrapper around <command>nm</command> that adds a
          plugin to the command line.  This program is only used
          to add "link time optization" and is not useful with the
          default build options.</para>
          <indexterm zone="ch-system-gcc gcc-nm">
            <primary sortas="b-gcc-nm">gc-nm</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="gcc-ranlib">
        <term><command>gcc-ranlib</command></term>
        <listitem>
          <para>A wrapper around <command>ranlib</command> that adds a
          plugin to the command line.  This program is only used
          to add "link time optization" and is not useful with the
          default build options.</para>
          <indexterm zone="ch-system-gcc gcc-ranlib">
            <primary sortas="b-gcc-ranlib">gc-ranlib</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="libasan">
        <term><command>libasan</command></term>
        <listitem>
          <para>The Address Sanitizer runtime library</para>
          <indexterm zone="ch-system-gcc libasan">
            <primary sortas="b-libasan">libasan</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="libgcov">
        <term><filename class="libraryfile">libgcov</filename></term>
        <listitem>
          <para>This library is linked in to a program when GCC is instructed
          to enable profiling</para>
          <indexterm zone="ch-system-gcc libgcov">
            <primary sortas="c-libgcov">libgcov</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="libgomp">
        <term><filename class="libraryfile">libgomp</filename></term>
        <listitem>
          <para>GNU implementation of the OpenMP API for multi-platform
          shared-memory parallel programming in C/C++ and Fortran</para>
          <indexterm zone="ch-system-gcc libgomp">
            <primary sortas="c-libgomp">libgomp</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="libiberty">
        <term><filename class="libraryfile">libiberty</filename></term>
        <listitem>
          <para>Contains routines used by various GNU programs, including
          <command>getopt</command>, <command>obstack</command>,
          <command>strerror</command>, <command>strtol</command>, and
          <command>strtoul</command></para>
          <indexterm zone="ch-system-gcc libiberty">
            <primary sortas="c-libiberty">libiberty</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="liblto_plugin">
        <term><filename class="libraryfile">liblto_plugin</filename></term>
        <listitem>
          <para>GCC's Link Time Optimization (LTO) plugin allows GCC to perform
          optimizations across compilation units.</para>
          <indexterm zone="ch-system-gcc liblto_plugin">
            <primary sortas="c-liblto_plugin*">liblto_plugin*</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="libmudflap">
        <term><filename class="libraryfile">libmudflap</filename></term>
        <listitem>
          <para>Contains routines that support GCC's bounds checking
          functionality</para>
          <indexterm zone="ch-system-gcc libmudflap">
            <primary sortas="c-libmudflap*">libmudflap*</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="libquadmath">
        <term><filename class="libraryfile">libquadmath</filename></term>
        <listitem>
          <para>GCC Quad Precision Math Library API</para>
          <indexterm zone="ch-system-gcc libquadmath">
            <primary sortas="c-libquadmath*">libquadmath*</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="libssp">
        <term><filename class="libraryfile">libssp</filename></term>
        <listitem>
          <para>Contains routines supporting GCC's stack-smashing protection
          functionality</para>
          <indexterm zone="ch-system-gcc libssp">
            <primary sortas="c-libssp*">libssp*</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>

      <varlistentry id="libtsan">
        <term><filename class="libraryfile">libtsan</filename></term>
        <listitem>
          <para>The Thread Sanitizer runtime library</para>
          <indexterm zone="ch-system-gcc libtsan">
            <primary sortas="c-libtsan">libtsan</primary>
          </indexterm>
        </listitem>
      </varlistentry>

    </variablelist>

  </sect2>

</sect1>