Bug#701082: gcc-4.7: gcc generates incorrect code with -O2 compiling libffi example

[Philip Ashmore <contact@philipashmore.com>]

On 23/02/13 09:40, Matthias Klose wrote:
> Am 23.02.2013 10:24, schrieb Philip Ashmore:
> > I did an
> >     apt-get -t experimental install gcc-4.7 gcc-4.8
> > and updated libffi
> >
> > gcc -O0 -o ffi-test ffi-test.c -lffi
> > ./ffi-test
> > Hello World!
> > This is cool!
> >
> > gcc -O1 -o ffi-test ffi-test.c -lffi
> > ./ffi-test
> > Hello World!
> > This is cool!
> >
> > gcc -O2 -o ffi-test ffi-test.c -lffi
> > ./ffi-test
> > Hello World!
> > Segmentation fault
> >
> > ldd ffi-test
> >          linux-vdso.so.1 (0x00007fff80fff000)
> >          libffi.so.6 =>  /usr/lib/x86_64-linux-gnu/libffi.so.6 (0x00007f9ffbaca000)
> >          libc.so.6 =>  /lib/x86_64-linux-gnu/libc.so.6 (0x00007f9ffb71d000)
> >          /lib64/ld-linux-x86-64.so.2 (0x00007f9ffbd0e000)
>
> so you tested with the updated gcc-4.7. could you repeat that with gcc-4.8?
Same results.

gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.7/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 4.7.2-21' 
--with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs 
--enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr 
--program-suffix=-4.7 --enable-shared --enable-linker-build-id 
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix 
--with-gxx-include-dir=/usr/include/c++/4.7 --libdir=/usr/lib 
--enable-nls --with-sysroot=/ --enable-clocale=gnu 
--enable-libstdcxx-debug --enable-libstdcxx-time=yes 
--enable-gnu-unique-object --enable-plugin --with-system-zlib 
--enable-objc-gc --with-cloog --enable-cloog-backend=ppl 
--disable-cloog-version-check --disable-ppl-version-check 
--enable-multiarch --with-arch-32=i586 --with-abi=m64 
--with-multilib-list=m32,m64,mx32 --with-tune=generic 
--enable-checking=release --build=x86_64-linux-gnu 
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.7.2 (Debian 4.7.2-21)

gcc-4.8 -v
Using built-in specs.
COLLECT_GCC=gcc-4.8
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.8/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 
4.8-20130217-1' --with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs 
--enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr 
--program-suffix=-4.8 --enable-shared --enable-linker-build-id 
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix 
--with-gxx-include-dir=/usr/include/c++/4.8 --libdir=/usr/lib 
--enable-nls --with-sysroot=/ --enable-clocale=gnu 
--enable-libstdcxx-debug --enable-libstdcxx-time=yes 
--enable-gnu-unique-object --enable-plugin --with-system-zlib 
--enable-objc-gc --enable-multiarch --with-arch-32=i586 --with-abi=m64 
--with-multilib-list=m32,m64,mx32 --with-tune=generic 
--enable-checking=release --build=x86_64-linux-gnu 
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.8.0 20130218 (experimental) [trunk revision 196115] 
(Debian 4.8-20130217-1)

Have you tried these yourself?