On 01/24/2012 11:05 AM, Uros Bizjak wrote: > Hello! > > Attached patch optimizes x86_64 gtm_jmpbuf layout to avoid copying > return address. Optimized layout uses the same trick as x86_32 - call > used registers are saved just below return address. And there is just > enough space in the call alignment hole to put all of them there. > > 2012-01-24 Uros Bizjak <ubiz...@gmail.com> > > * config/x86/target.h (gtm_jmpbuf) [__x86_64__]: Move rip to the > end of struct. > * config/x86/sjlj.S (_ITM_beginTransaction) [__x86_64__]: Update > offset values. Do not copy return address. Decrement stack > by 56 bytes only. > (GTM_longjump) [__x86_64__]: Update offset values.
Ok. > BTW: Do we really need move at the end of GTM_longjump: > > movq 48(%rsi), %r15 > movq 56(%rsi), %rdx >>> movl %edi, %eax Yes, that copies the first argument to the return register. r~
