http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59086
--- Comment #5 from Alexander Ivchenko <aivchenk at gmail dot com> --- I understand the technical reasons of the complexity of the correct and efficient register allocation here, but what I don't understand is this: $> gcc_4.7 test.c -c -fPIC -mstackrealign -march=core-avx2 -m32 $> gcc_4.8 test.c -c -fPIC -mstackrealign -march=core-avx2 -m32 $> gcc_4.9 test.c -c -fPIC -mstackrealign -march=core-avx2 -m32 test.c: In function 'testFunc': test.c:7:3: error: 'asm' operand has impossible constraints __asm__( ^ How can we allow to break the user code with the release version of the compiler here..?