6.12. GCC-4.1.1

The GCC package contains the GNU compiler collection, which includes the C and C++ compilers.

Approximate build time: 22 SBU testsuite included
Required disk space: 681 MB testsuite included

6.12.1. Installation of GCC

Apply a sed substitution that will suppress the installation of libiberty.a. The version of libiberty.a provided by Binutils will be used instead:

sed -i 's/install_to_$(INSTALL_DEST) //' libiberty/Makefile.in

The bootstrap build performed in Section 5.4, “GCC-4.1.1 - Pass 1” built GCC with the -fomit-frame-pointer compiler flag. Non-bootstrap builds omit this flag by default, so apply the following sed to use it in order to ensure consistent compiler builds.

sed -i 's/^XCFLAGS =$/& -fomit-frame-pointer/' gcc/Makefile.in

The fixincludes script is known to occasionally erroneously attempt to "fix" the system headers installed so far. As the headers installed by GCC-4.1.1 and Glibc-2.5 are known to not require fixing, issue the following command to prevent the fixincludes script from running:

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

GCC provides a gccbug 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.

sed -i 's/@have_mktemp_command@/yes/' gcc/gccbug.in

The GCC documentation recommends building GCC outside of the source directory in a dedicated build directory:

mkdir -v ../gcc-build
cd ../gcc-build

Prepare GCC for compilation:

../gcc-4.1.1/configure --prefix=/usr \
    --libexecdir=/usr/lib --enable-shared \
    --enable-threads=posix --enable-__cxa_atexit \
    --enable-clocale=gnu --enable-languages=c,c++

Compile the package:

make
[Important]

Important

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

Test the results, but do not stop at errors:

make -k check

To receive a summary of the test suite results, run:

../gcc-4.1.1/contrib/test_summary

For only the summaries, pipe the output through grep -A7 Summ.

Results can be compared with those located at http://www.linuxfromscratch.org/lfs/build-logs/development/.

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 libmudflap tests are known be particularly problematic as a result of a bug in GCC (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.

Install the package:

make install

Some packages expect the C preprocessor to be installed in the /lib directory. To support those packages, create this symlink:

ln -sv ../usr/bin/cpp /lib

Many packages use the name cc to call the C compiler. To satisfy those packages, create a symlink:

ln -sv gcc /usr/bin/cc

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:

echo 'main(){}' > dummy.c
cc dummy.c -Wl,--verbose &> dummy.log
readelf -l a.out | grep ': /lib'

If everything is working correctly, there should be no errors, and the output of the last command will be (allowing for platform-specific differences in dynamic linker name):

[Requesting program interpreter: /lib/ld-linux.so.2]

Now make sure that we're setup to use the correct startfiles:

grep -o '/usr/lib.*/crt[1in].* .*' dummy.log

If everything is working correctly, there should be no errors, and the output of the last command will be:

/usr/lib/gcc/i686-pc-linux-gnu/4.1.1/../../../crt1.o succeeded
/usr/lib/gcc/i686-pc-linux-gnu/4.1.1/../../../crti.o succeeded
/usr/lib/gcc/i686-pc-linux-gnu/4.1.1/../../../crtn.o succeeded

Next, verify that the new linker is being used with the correct search paths:

grep 'SEARCH.*/usr/lib' dummy.log |sed 's|; |\n|g'

If everything is working correctly, there should be no errors, and the output of the last command will be:

SEARCH_DIR("/usr/i686-pc-linux-gnu/lib")
SEARCH_DIR("/usr/local/lib")
SEARCH_DIR("/lib")
SEARCH_DIR("/usr/lib");

Next make sure that we're using the correct libc:

grep "/lib/libc.so.6 " dummy.log

If everything is working correctly, there should be no errors, and the output of the last command will be:

attempt to open /lib/libc.so.6 succeeded

Lastly, make sure GCC is using the correct dynamic linker:

grep found dummy.log

If everything is working correctly, there should be no errors, and the output of the last command will be (allowing for platform-specific differences in dynamic linker name):

found ld-linux.so.2 at /lib/ld-linux.so.2

If the output does not appear as shown above or is not received at all, then something is seriously wrong. Investigate and retrace the steps to find out where the problem is and correct it. The most likely reason is that something went wrong with the specs file adjustment. Any issues will need to be resolved before continuing on with the process.

Once everything is working correctly, clean up the test files:

rm -v dummy.c a.out dummy.log

6.12.2. Contents of GCC

Installed programs: c++, cc (link to gcc), cpp, g++, gcc, gccbug, and gcov
Installed libraries: libgcc.a, libgcc_eh.a, libgcc_s.so, libstdc++.{a,so}, and libsupc++.a

Short Descriptions

cc

The C compiler

cpp

The C preprocessor; it is used by the compiler to expand the #include, #define, and similar statements in the source files

c++

The C++ compiler

g++

The C++ compiler

gcc

The C compiler

gccbug

A shell script used to help create useful bug reports

gcov

A coverage testing tool; it is used to analyze programs to determine where optimizations will have the most effect

libgcc

Contains run-time support for gcc

libstdc++

The standard C++ library

libsupc++

Provides supporting routines for the C++ programming language