[llvm] [X86] Use GFNI for vXi8 shifts/rotates (PR #89115)

[via llvm-commits]

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@@ -31345,7 +31392,8 @@ static SDValue LowerBITREVERSE(SDValue Op, const X86Subtarget &Subtarget,
   // If we have GFNI, we can use GF2P8AFFINEQB to reverse the bits.
   if (Subtarget.hasGFNI()) {
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shamithoke wrote:

>From what I understand, GFNI can be supported even without AVX. So we don't need to have a check for AVX here. 
https://community.intel.com/t5/Intel-ISA-Extensions/Requirements-for-GFNI-without-AVX-AVX-512/m-p/1228325?profile.language=en&countrylabel=Argentina

https://github.com/llvm/llvm-project/pull/89115