[llvm] [X86] Prefer AVX512 VPCMP against zero over splat(1) for sle/slt (PR #216716)

[Simon Pilgrim via llvm-commits]

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@@ -58455,17 +58479,22 @@ static SDValue combineSetCC(SDNode *N, SelectionDAG &DAG,
           CmpKnown.Zero.isSignBitSet() || CmpKnown.One.isSignBitSet();
     }
     if (CanMakeSigned || ISD::isSignedIntSetCC(CC)) {
+      // AVX512 can encode LE/GE against zero; do not turn that into LT/GT
+      // vs ±1.
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RKSimon wrote:

single line
```suggestion
      // AVX512 encodes LE/GE vs 0; do not turn that into LT/GT vs ±1.
```

https://github.com/llvm/llvm-project/pull/216716