[llvm] [DAG] Generalize fold (not (neg x)) -> (add X, -1) (PR #154348)

[Craig Topper via llvm-commits]

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@@ -9993,10 +9993,29 @@ SDValue DAGCombiner::visitXOR(SDNode *N) {
   if (N0.getOpcode() == ISD::SUB && isAllOnesConstant(N1)) {
     SDValue Y = N0.getOperand(0);
     SDValue X = N0.getOperand(1);
-    if (isa<ConstantSDNode>(Y) || N0.hasOneUse()) {
-      SDValue NotY =
-          DAG.getNode(ISD::XOR, DL, VT, Y, DAG.getAllOnesConstant(DL, VT));
-      return DAG.getNode(ISD::ADD, DL, VT, X, NotY);
+
+    // Avoid infinite recursion with
+    // Fold (and X, (add (not Y), Z)) -> (and X, (not (sub Y, Z)))
+    bool hasAndUsers = false;
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topperc wrote:

Capitalize variables name.

https://github.com/llvm/llvm-project/pull/154348