On Tue, Jul 10, 2012 at 1:57 AM, Uros Bizjak <ubiz...@gmail.com> wrote: > On Tue, Jul 10, 2012 at 9:04 AM, Steven Bosscher <stevenb....@gmail.com> > wrote: >>>> TARGET_BRANCH_PREDICTION_HINTS isn't used at all. This patch removes it. >>>> Bootstrapped&tested (incl. -m32) on x86_64-unknown-linux-gnu. OK for trunk? >>> >>> This infrastructure can be used for future targets, so let's leave it as is. >> >> Yes, I suppose that's theoretically possible. However, I don't think >> this is very likely to happen. The branch hints only ever were >> supported for P4, but even Intel's own ICC never emits them >> (http://sources.redhat.com/ml/binutils/2004-07/msg00322.html). In >> fact, the whole Netburst microachitecture appears to have been >> abandoned (in favor of the ppro microachitecture). For EM64T another >> form of branch hints was introduced (which GCC doesn't support and ICC >> doesn't emit). >> >> So any future target that would need this, would have to be a 32-bits, >> deep-pipeline microarchitecture. I personally don't believe that such >> an architecture will emerge, given the history of failure of this >> concept. >> >> Are these arguments reason enough for you to reconsider? :-) > > Arguments are indeed good, but I'd like to hear HJ's opinion about > future targets. > > Anyway, this functionality can be reimplemented from the scratch for > future target, but OTOH, it is not a mainenance burden at all... >
I'd like to keep it since we are planning to update and use it. Thanks. -- H.J.
