On Thu, Jun 15, 2006 at 12:12:38AM +0900, Atsushi Nemoto wrote: > If a system call returned an error, glibc must save the result to > errno, which is thread-local, so RDHWR used. I can understand this > scenario. But it seems the RDHWR is often called on non-error cases. Libc uses TLS for many things other than just errno. The GCC port knows how to generate the agreed-upon rdhwr instruction directly. > For example, in the code below, RDHWR is placed _before_ checking the > error. I suppose these instructions were reordered by gcc's > optimization, but the optimization would have large negative effect in > this case. You'd have to figure out how to get GCC not to eagerly schedule the rdhwr. This might be quite hard. I don't know much about this part of the scheduler. -- Daniel Jacobowitz CodeSourcery
