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Re: x86 patch: SSE-based FP<=>int conversions, round 2
On Wed, 13 Dec 2006, Stuart Hastings wrote:
> >In general if one makes changes especially to the "strange looking"
> >aspects of x86-64 which implement things in seemingly suboptimal ways
> >(going over memory, or going different ways depending on data flow
> >direction, or doing stuff separately which can also be done in one
> >insn) one should be extremely cautious and measure all these changes on
> >AMD64 carefully. Much of the funny stuff has a reason.
> O.K., if I add
> if (TARGET_ATHLON_K8)
> to the body of this pattern, would that satisfy?
I guess, let's Honza decide ...
> >This for instance is something you don't want in general :) You want
> >to go over memory here (for AMD64 at least, haven't checked with
> I been told that Intel hardware dislikes differently-sized load/store
> operations on the same location.
Oh, sorry. Yes this is the same for AMD due to store forwarding you want
to have equal sized stores and loads. I missed that this was about
%edx->mem32;%eax->mem32;mem64->%xmm (and thought it was about