[PATCH][X86] Add ISel patterns to select SSE3/AVX ADDSUB instructions.

[Jim Grosbach]

This is excellent!

Can you add a brief comment to the patch explaining the i32 constants in the input patterns and how they map to the masks?

LGTM w/ that addition.

-Jim


> On Jun 17, 2014, at 7:41 AM, Andrea Di Biagio <andrea.dibiagio at gmail.com> wrote:
> 
> Hi,
> 
> this patch adds ISel patterns to select SSE3/AVX ADDSUB instructions
> from a sequence of "vadd + vsub + blend".
> 
> Example:
> 
> ///
> typedef float float4 __attribute__((ext_vector_type(4)));
> 
> float4 foo(float4 A, float4 B) {
>  float4 X = A - B;
>  float4 Y = A + B;
>  return (float4){X[0], Y[1], X[2], Y[3]};
> }
> ///
> 
> Before this patch, (with flag -mcpu=corei7) we produced the following
> assembly sequence:
>  movaps  %xmm0, %xmm2
>  addps   %xmm1, %xmm2
>  subps   %xmm1, %xmm0
>  blendps $10, %xmm2, %xmm0
> 
> 
> With this patch, we now produce a single
>  addsubps  %xmm1, %xmm0
> 
> Please let me know if ok to commit.
> 
> Thanks,
> Andrea Di Biagio.
> <patch-addsub.diff>