http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52813
--- Comment #3 from Uros Bizjak <ubizjak at gmail dot com> 2012-04-01 18:58:27 UTC --- (In reply to comment #2) > I don't expect the compiler to analyze the asm string. I expect the compiler > to respect my clobber list. > > I told GCC that I would clobber %rsp. Any other register that I put in the > clobber list causes GCC to save that register to the stack or to another > register before the asm and restore it from the stack/register after the asm. > For example: %rsp is considered a "fixed" register, used for fixed purposes all throughout the compiled code and are therefore not available for general allocation. So, save %rsp at the beginning of your asm code and restore it at the end.
