source: chapter08/gcc.xml@ d8a492a

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

  </sect2>

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

    <para>First, apply a patch to fix some regressions and to cope
    with the removal of an obsolete kernel header in linux-5.13:</para>

<screen><userinput remap="pre">patch -Np1 -i ../gcc-&gcc-version;-upstream_fixes-1.patch</userinput></screen>

    <para>If building on x86_64, change the default directory name for 64-bit
    libraries to <quote>lib</quote>:</para>

<screen><userinput remap="pre">case $(uname -m) in
  x86_64)
    sed -e '/m64=/s/lib64/lib/' \
        -i.orig gcc/config/i386/t-linux64
  ;;
esac</userinput></screen>

    <para>The GCC documentation recommends building GCC in a dedicated build directory:</para>

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

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

<screen><userinput remap="configure">../configure --prefix=/usr            \
             LD=ld                    \
             --enable-languages=c,c++ \
             --disable-multilib       \
             --disable-bootstrap      \
             --with-system-zlib</userinput></screen>

    <para>Note that for other programming languages there are some prerequisites that
    are not yet available. See the
    <ulink url="&blfs-book;general/gcc.html">BLFS Book GCC page</ulink>
    for instructions on how to build all of GCC's supported languages.</para>

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

      <varlistentry>
        <term><parameter>LD=ld</parameter></term>
        <listitem>
          <para>This parameter makes the configure script use the ld installed
          by the binutils built earlier in this chapter, rather than
          the cross-built version which would otherwise be used.</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 default
   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 as a non-privileged user, but do not stop at errors:</para>

<screen><userinput remap="test">chown -Rv tester . 
su tester -c "PATH=$PATH make -k check"</userinput></screen>

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

<screen><userinput remap="test">../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="https://gcc.gnu.org/ml/gcc-testresults/"/>.</para>

    <para>In g++, three tests in constexpr-52830 are known to fail and
    also to be treated as unexpected successes (XPASS).  This is because
    an <quote>internal compiler error</quote> on this test is fixed, but
    the compiler still rejects some valid code.</para>

    <!--  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96322
          https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71367 -->
    <para>In libstdc++, one numpunct test and six tests related to get_time are
    known to fail.  These are all because the locale definitions in glibc have
    changed but libstdc++ does not currently support those changes.</para>

<!--<para>Additionally the following tests related to the following files
    are known to fail with glibc-2.33: asan_test.C, co-ret-17-void-ret-coro.C, 
    pr95519-05-gro.C, pr80166.c.</para>
-->

<!-- don't fail anymore after the move of iana-etc and /etc/hosts
    <para>Two tests named lookup.cc and reverse.cc in experimental/net
    are known to fail in LFS chroot environment because they require
    /etc/hosts and iana-etc.</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.
    Unless the test results are vastly different from those at the above URL,
    it is safe to continue.</para>

    <!--note><para>
      On some combinations of kernel configuration and AMD processors
      there may be more than 1100 failures in the gcc.target/i386/mpx
      tests (which are designed to test the MPX option on recent
      Intel processors). These can safely be ignored on AMD
      processors. These tests will also fail on Intel processors if MPX support
      is not enabled in the kernel even though it is present on the CPU.
    </para></note-->

    <!-- PR 91085, will be fixed in GCC 12. -->
    <para>Install the package and remove an unneeded directory:</para>

<screen><userinput remap="install">make install
rm -rf /usr/lib/gcc/$(gcc -dumpmachine)/&gcc-version;/include-fixed/bits/</userinput></screen>

    <para>The GCC build directory is owned by <systemitem class="username">
    tester</systemitem> now and the ownership of the installed header
    directory (and its content) will be incorrect.  Change the ownership to
    <systemitem class="username">root</systemitem> user and group:</para>

<screen><userinput remap="install">chown -v -R root:root \
    /usr/lib/gcc/*linux-gnu/&gcc-version;/include{,-fixed}</userinput></screen>

    <para>Create a symlink required by the <ulink
    url="https://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch03s09.html">FHS</ulink>
    for "historical" reasons.</para>

<screen><userinput remap="install">ln -svr /usr/bin/cpp /usr/lib</userinput></screen>
  <!-- already done earlier
    <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">ln -sfv ../../libexec/gcc/$(gcc -dumpmachine)/&gcc-version;/liblto_plugin.so \
        /usr/lib/bfd-plugins/</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
    some sanity checks:</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/x86_64-pc-linux-gnu/&gcc-version;/../../../../lib/crt1.o succeeded
/usr/lib/gcc/x86_64-pc-linux-gnu/&gcc-version;/../../../../lib/crti.o succeeded
/usr/lib/gcc/x86_64-pc-linux-gnu/&gcc-version;/../../../../lib/crtn.o succeeded</computeroutput></screen>

  <para>Depending on your machine architecture, the above may differ slightly.
  The difference will be the name of the directory
  after <filename class="directory">/usr/lib/gcc</filename>. 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/x86_64-pc-linux-gnu/&gcc-version;/include
 /usr/local/include
 /usr/lib/gcc/x86_64-pc-linux-gnu/&gcc-version;/include-fixed
 /usr/include</computeroutput></screen>

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

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

   <para>A 32-bit system may see a few different directories. For example, here
   is the output from an i686 machine:</para>

<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>

    <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, gcov, gcov-dump, and gcov-tool</seg>

        <seg>libasan.{a,so}, libatomic.{a,so}, libcc1.so, libgcc.a, libgcc_eh.a,
        libgcc_s.so, libgcov.a, libgomp.{a,so}, libitm.{a,so},
        liblsan.{a,so}, liblto_plugin.so,
        libquadmath.{a,so}, libssp.{a,so}, libssp_nonshared.a,
        libstdc++.{a,so}, libstdc++fs.a, libsupc++.a, libtsan.{a,so},
        and libubsan.{a,so}</seg>

        <seg>/usr/include/c++, /usr/lib/gcc, /usr/libexec/gcc, and 
        /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 optimization" 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 optimization" 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 optimization" 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="gcov-dump">
        <term><command>gcov-dump</command></term>
        <listitem>
          <para>Offline gcda and gcno profile dump tool</para>
          <indexterm zone="ch-system-gcc gcov-dump">
            <primary sortas="b-gcov-dump">gcov-dump</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="gcov-tool">
        <term><command>gcov-tool</command></term>
        <listitem>
          <para>Offline gcda profile processing tool</para>
          <indexterm zone="ch-system-gcc gcov-tool">
            <primary sortas="b-gcov-tool">gcov-tool</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="libasan">
        <term><filename class="libraryfile">libasan</filename></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="libatomic">
        <term><filename class="libraryfile">libatomic</filename></term>
        <listitem>
          <para>GCC atomic built-in runtime library</para>
          <indexterm zone="ch-system-gcc libatomic">
            <primary sortas="b-libatomic">libatomic</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="libcc1">
        <term><filename class="libraryfile">libcc1</filename></term>
        <listitem>
          <para>The C preprocessing library</para>
          <indexterm zone="ch-system-gcc libcc1">
            <primary sortas="b-libcc1">libcc1</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="liblsan">
        <term><filename class="libraryfile">liblsan</filename></term>
        <listitem>
          <para>The Leak Sanitizer runtime library</para>
          <indexterm zone="ch-system-gcc liblsan">
            <primary sortas="c-liblsan">liblsan</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="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="libstdcfs">
        <term><filename class="libraryfile">libstdc++fs</filename></term>
        <listitem>
          <para>ISO/IEC TS 18822:2015 Filesystem library</para>
          <indexterm zone="ch-system-gcc libstdcfs">
            <primary sortas="c-libstdc++fs">libstdc++fs</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>

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

    </variablelist>

  </sect2>

</sect1>