Created attachment 120603 [details] disassembled release build with -mstackrealign Here is my release build with -mstackrealign that works: http://haagch.frickel.club/files/lib32-llvm-libs-svn-256101-1-x86_64.pkg.tar.gz http://haagch.frickel.club/files/lib32-llvm-svn-256101-1-x86_64.pkg.tar.gz They are compiled with -march=native for my ivy bridge cpu, so maybe that has some influence. Disassembling the same function shows different offsets for movaps: 0x0047a805 <+69>: movaps %xmm0,-0x48(%ebp) 0x0047a815 <+85>: movaps %xmm0,-0x38(%ebp) You can check with gdb -q /usr/lib32/libLLVM-3.8svn.so -ex "disassemble LLVMAddTargetDependentFunctionAttr" Probably: movaps %xmm0,-0x48(%ebp) is right movaps %xmm0,-0x40(%ebp) is wrong