[llvm-commits] [PATCH] Replace SUB with CMP if possible on X86

[Chandler Carruth]

On Wed, May 30, 2012 at 8:56 PM, Manman Ren <mren at apple.com> wrote:

>
> PING
>

Give it at least a day.... =/

I don't know the peephole optimizer well enough to really review this.


>
> On May 30, 2012, at 1:55 PM, Manman Ren wrote:
>
> >
> > SUB with memory operand should not be optimized.
> > Updated patch is attached.
> >
> > Manman
> > <convert_sub_to_cmp.patch>
> > On May 30, 2012, at 11:44 AM, Manman Ren wrote:
> >
> >>
> >> Hi All,
> >>
> >> This patch is to optimize generated code from
> >>      movq    %rdi, %rax
> >>      subq    %rsi, %rax
> >>      cmovsq  %rsi, %rdi
> >>      movq    %rdi, %rax
> >>
> >> to
> >>      cmpq    %rsi, %rdi
> >>      cmovsq  %rsi, %rdi
> >>      movq    %rdi, %rax
> >>
> >> The only criterion to perform this optimization is that the actual
> result of SUB is not used.
> >>
> >> Thanks,
> >> Manman
> >>
> >> <convert_sub_to_cmp.patch>
> >
>
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