[llvm-commits] Please review - One more shuffle optimization for AVX

[Demikhovsky, Elena]

Hi,

I have a bunch of optimizations for AVX and AVX2 code that I recently did. Most of them show significant performance speedup on real workloads.
I’ll send it to review one by one accompanied with appropriate tests.

The current patch optimizes frequently used shuffle patterns and gives these instruction sequence reduction.
Before:
       vshufps $-35, %xmm1, %xmm0, %xmm2 ## xmm2 = xmm0[1,3],xmm1[1,3]
        vpermilps       $-40, %xmm2, %xmm2 ## xmm2 = xmm2[0,2,1,3]
        vextractf128    $1, %ymm1, %xmm1
        vextractf128    $1, %ymm0, %xmm0
        vshufps $-35, %xmm1, %xmm0, %xmm0 ## xmm0 = xmm0[1,3],xmm1[1,3]
        vpermilps       $-40, %xmm0, %xmm0 ## xmm0 = xmm0[0,2,1,3]
        vinsertf128     $1, %xmm0, %ymm2, %ymm0
After:
       vshufps $13, %ymm0, %ymm1, %ymm1 ## ymm1 = ymm1[1,3],ymm0[0,0],ymm1[5,7],ymm0[4,4]
       vshufps $13, %ymm0, %ymm0, %ymm0 ## ymm0 = ymm0[1,3,0,0,5,7,4,4]
       vunpcklps       %ymm1, %ymm0, %ymm0 ## ymm0 = ymm0[0],ymm1[0],ymm0[1],ymm1[1],ymm0[4],ymm1[4],ymm0[5],ymm1[5]

  Thank you

- Elena


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