[llvm] [X86][ISel] Improve VPTERNLOG matching for negated logic trees (PR #164863)

[Phoebe Wang via llvm-commits]

================
@@ -4740,6 +4737,34 @@ bool X86DAGToDAGISel::tryVPTERNLOG(SDNode *N) {
     return SDValue();
   };
 
+  // Identify and (optionally) peel an outer NOT that wraps a pure logic tree
+  auto tryPeelOuterNotWrappingLogic = [&](SDNode *Op) {
+    if (Op->getOpcode() == ISD::XOR && Op->hasOneUse() &&
+        ISD::isBuildVectorAllOnes(Op->getOperand(1).getNode())) {
+      SDValue InnerOp = Op->getOperand(0);
+
+      if (!getFoldableLogicOp(InnerOp)) {
+        return SDValue();
+      }
+
+      SDValue InnerN0 = InnerOp.getOperand(0);
+      SDValue InnerN1 = InnerOp.getOperand(1);
+      if (getFoldableLogicOp(InnerN1) || getFoldableLogicOp(InnerN0))
----------------
phoebewang wrote:

```suggestion
      N0 = InnerOp.getOperand(0);
      N1 = InnerOp.getOperand(1);
      if ((FoldableOp = getFoldableLogicOp(N1))) {
        A = N0;
        return InnerOp;
      }
      if ((FoldableOp = getFoldableLogicOp(N0))) {
        A = N1;
        return InnerOp;
      }
      return SDValue();
```

https://github.com/llvm/llvm-project/pull/164863