control: forwarded -1 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67736
On 2015-09-27 21:02, Andreas Cadhalpun wrote: > Package: gcc-5 > Version: 5.2.1-17 > Severity: important > Control: affects -1 ffmpeg > X-Debbugs-Cc: debian-m...@lists.debian.org > > > Dear Maintainer, > > ffmpeg 7:2.8-1 failed to build on mips64el due to a test failure. > > I investigated the problem and it turns out to be caused by a compiler bug > that can be avoided by using '-fno-expensive-optimizations'. > > Attached is a reduced test case: > $ ls > Makefile main.c test.c > $ make > cc -fPIC -O2 -fno-expensive-optimizations -c -o working.o test.c > cc -shared -o libworking.so working.o > cc -o working main.c -L. -lworking > cc -fPIC -O2 -c -o broken.o test.c > cc -shared -o libbroken.so broken.o > cc -o broken main.c -L. -lbroken > LD_LIBRARY_PATH=. ./working || true > A f00000100 101 > B f00000100 101 > working > LD_LIBRARY_PATH=. ./broken || true > A f00000100 101 > broken > > In the broken version the '& 0xFFFFFFFF' in following line gets ignored: > if (*last == ((state | buf) & 0xFFFFFFFF)) > > This also fails with gcc-4.9 and gcc-4.8, so it is a longstanding problem. Thanks for the detailed test case. I have just reported the bug upstream, I hope someone will come with a fix soon. Aurelien -- Aurelien Jarno GPG: 4096R/1DDD8C9B aurel...@aurel32.net http://www.aurel32.net
