[Bug target/56866] gcc 4.7.x/gcc-4.8.x with '-O3 -march=bdver2' misscompiles glibc-2.17/crypt/sha512.c

[winfried.magerl@t-online.de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56866

--- Comment #7 from Winfried Magerl <winfried.magerl@t-online.de> 2013-04-12 18:42:48 UTC ---
Hi,

On Fri, Apr 12, 2013 at 12:42:26PM +0000, mikpe at it dot uu.se wrote:
> --- Comment #6 from Mikael Pettersson <mikpe at it dot uu.se> 2013-04-12 12:42:26 UTC --- 
> I've bootstrapped and regtested gcc-4.7.3 on an Opteron 6278, with and without 
> --with-arch=bdver1.  With --with-arch=bdver1 there were numerous regressions in 
> gcc.dg/vect/ and gcc.target/i386/{,l-}fma*, and one in 
> gcc.target/i386/pr42542-4a.c.  I don't know if these indicate wrong-code or 
> missed-optimization. 

something like egrep '^FAIL.+execution' to get the scary
errors (currently I think all that scan-*-errors are simply
false positive).

> I'd be willing to run specific wrong-code test cases on this machine, if 
> they're completely standalone (not depending on recent glibc). 

Don't know how to pick out single gcc-testcases from the
testsuite for standalone-testing.

In any case it's possible th check the whole package. gcc/glibc have a big
test-suite and it's not necessary to install them to run the test-suite.
And I have already provided the differences I see when enabling 'bdver2'
compared with 'amdfam10'

for gcc something like this (out of the head with typos included):

--------------------------------------------
cd /to/your/favorite/builddir
wget ftp:///ftp.gnu.org/gnu/gcc/gcc-4.8.0/gcc-4.8.0.tar.bz2
tar -xf gcc-4.8.0.tar.bz2
mkdir build
mkdir build-bdver1
cd build/
../gcc-4.8.0/configure --enable-multilib=no --enable-languages='c,c++'
make -j8 >& make.out
make -j8 -k check >& check.out
../gcc-4.8/contrib/test_summary >& test_summary.out
cd ../build-bdver1
../gcc-4.8.0/configure --enable-multilib=no --enable-languages='c,c++'
--with-arch=bdver1
make -j8 >& make.out
make -j8 -k check >& check.out
../gcc-4.8/contrib/test_summary >& test_summary.out
cd ..
diff -u build/test_summary.out build-bdver1/test_summary.out | egrep
'^\+.+execution'
----------------------------------------------

some notes:
    --enable-multilib=no        -> only x86_64
    --enable-languages='c,c++'    -> only c-tests are of interest
    make -j8            -> depends on your CPU
    egrep '^\+.+execution'        -> for easier comparison with the diff I've
provided
    --with-arch=bdver1        -> your CPU is bdver1

for glibc it's something similar:

--------------------------------------------
cd /to/your/favorite/builddir
wget ftp:///ftp.gnu.org/glibc/glibc-2.17.tar.xz
tar -xf glibc-2.17.tar.xz
mkdir build
mkdir build-bdver1
cd build/
export CC='gcc'
export CFLAGS='-O3'
../glibc-2.17/configure
make -j8 >& make.out
make -k -j8 check >& check.out
cd ../build-bdver1
export CC='gcc -march=bdver1'
../glibc-2.17/configure
make -j8 >& make.out
make -k -j8 check >& check.out
cd ..
fgrep '***' build/check.out build-bdver1/check.out
--------------------------------------------

To ensure it's XOP in glibc you can use CC='gcc -mxop' instead
of CC='gcc -march=bdver1'.

regards

    winfried