On Mon, Feb 20, 2012 at 7:31 PM, Jakub Jelinek <ja...@redhat.com> wrote: > On Mon, Feb 20, 2012 at 07:27:48PM +0100, Uros Bizjak wrote: >> IIUC the documentation, the fallback label is a parameter to xbegin >> insn, but the insn itself doesn't jump anywhere - it just records the >> parameter as a fallback address. However, there is no guarantee that >> the fallback code is exactly at (pc)+6, so we have to use asm labels >> here. > > 6 bytes is the length of the xbegin instruction, so xbegin .+6 > says that it has the fallback address at the immediately next insn > after xbegin. Which is the _xbegin () semantics.
No! From 319433-012a.pdf, page 523, it says that tempRIP = RIP + SignExtend (IMM), where RIP is instruction following XBEGIN instruction. cmp and jcc that follows xbegin are 5 bytes long... Uros.
