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Re: optimizations
- From: Reza Roboubi <reza at linisoft dot com>
- To: Andrew Pinski <pinskia at physics dot uc dot edu>
- Cc: gcc-help <gcc-help at gcc dot gnu dot org>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>, gcc_bugs <gcc-bugs at gcc dot gnu dot org>
- Date: Tue, 14 Jan 2003 22:28:43 -0800
- Subject: Re: optimizations
- References: <8682D892-2847-11D7-A1D5-000393A6D2F2@physics.uc.edu>
Andrew Pinski wrote:
>
> On Tuesday, Jan 14, 2003, at 16:49 US/Pacific, Reza Roboubi wrote:
>
> > Could you please also tell me if 3.3 and 3.4 remove the extra mov's in
> > and out
> > of %eax. Ideally, there should be no more than 4 instructions in the
> > critical
> > loop.
> >
>
> For some reason it is not (even with -fnew-ra), but on PPC there is no
> extra load/store.
Hmmm. That's interesting. It might be a bug (or overlooked opportunity) on the
PC.
>
> Thanks,
> Andrew Pinski
>
> PS here is the asm for the loop of i[3-6]686, pentium4:
>
> .L2:
> movl -4(%ebp), %eax <== still does the store
> cmpl $16, %eax
> je .L7
> incl %eax
> movl %eax, -4(%ebp) <== and load
> jmp .L2
> .L7:
>
> I do not have access to the machine with 3.{3,4} on PPC right now.
I really appreciate your help Andrew.
Reza.