lfs-book/chapter06/gcc.xml

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

  <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>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 <command>fixincludes</command> script is known to occasionally
    erroneously attempt to &quot;fix&quot; the system headers installed so far. As
    the headers installed by GCC-&gcc-version; and Glibc-&glibc-version; are known
    to not require fixing, issue the following command to prevent the
    <command>fixincludes</command> script from running:</para>

<screen><userinput>sed -i 's@\./fixinc\.sh@-c true@' gcc/Makefile.in</userinput></screen>

    <para>GCC provides a <command>gccbug</command> script which detects at
    compile time whether mktemp is present, and hardcodes the result in a test.
    This will cause the script to fall back to using less random names for
    temporary files.  We will be installing mktemp later, so the following sed
    will simulate its presence:</para>

<screen><userinput>sed -i 's/@have_mktemp_command@/yes/' gcc/gccbug.in</userinput></screen>

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

<screen><userinput>mkdir -v ../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++ \
    --disable-multilib</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>To receive a summary of the test suite results, run:</para>

<screen><userinput>../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;"/>.</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 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>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 -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>ln -sv gcc /usr/bin/cc</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/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='a'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='b'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='c'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='d'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='e'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='f'])"/>

<screen><computeroutput>/usr/lib/gcc/x86_64-unknown-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 gcc 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/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='g'])"/>

<screen><userinput>grep -B3 '^ /usr/include' dummy.log</userinput></screen>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='h'])"/>

<screen><computeroutput>#include &lt;...&gt; search starts here:
 /usr/local/include
 /usr/lib/gcc/x86_64-unknown-linux-gnu/&gcc-version;/include
 /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>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='i'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='j'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='k'])"/>

<screen><computeroutput>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 more directories. For example, here
   is the output from a 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/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='l'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='m'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='n'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='o'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='p'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='q'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='r'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='s'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='t'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='u'])"/>

    <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
    href="readjusting.xml"
    xpointer="xpointer(//*[@os='v'])"/>

  </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, libmudflap.{a,so},
        libssp.{a,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="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="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="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="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>

    </variablelist>

  </sect2>

</sect1>