[LLVMdev] Please benchmark new x86 vector shuffle lowering, planning to make it the default very soon!

[Chandler Carruth]

On Fri, Sep 5, 2014 at 9:32 AM, Robert Lougher <rob.lougher at gmail.com>
wrote:

> Unfortunately, another team, while doing internal testing has seen the
> new path generating illegal insertps masks.  A sample here:
>
>     vinsertps    $256, %xmm0, %xmm13, %xmm4 # xmm4 = xmm0[0],xmm13[1,2,3]
>     vinsertps    $256, %xmm1, %xmm0, %xmm6 # xmm6 = xmm1[0],xmm0[1,2,3]
>     vinsertps    $256, %xmm13, %xmm1, %xmm7 # xmm7 = xmm13[0],xmm1[1,2,3]
>     vinsertps    $416, %xmm1, %xmm4, %xmm14 # xmm14 =
> xmm4[0,1],xmm1[2],xmm4[3]
>     vinsertps    $416, %xmm13, %xmm6, %xmm13 # xmm13 =
> xmm6[0,1],xmm13[2],xmm6[3]
>     vinsertps    $416, %xmm0, %xmm7, %xmm0 # xmm0 =
> xmm7[0,1],xmm0[2],xmm7[3]
>
> We'll continue to look into this and do additional testing.
>

Interesting. Let me know if you get a test case. The insertps code path was
added recently though and has been much less well tested. I'll start fuzz
testing it and should hopefully uncover the bug.
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