[llvm] [DAGCombiner] Add hasOneUse checks for folding (not (add X, -1)) to (neg X) (PR #126667)

[Matt Arsenault via llvm-commits]

================
@@ -9702,7 +9702,7 @@ SDValue DAGCombiner::visitXOR(SDNode *N) {
   }
 
   // fold (not (add X, -1)) -> (neg X)
-  if (isAllOnesConstant(N1) && N0.getOpcode() == ISD::ADD &&
+  if (isAllOnesConstant(N1) && N0.getOpcode() == ISD::ADD && N0.hasOneUse() &&
       isAllOnesOrAllOnesSplat(N0.getOperand(1))) {
----------------
arsenm wrote:

```suggestion
  if (N0.getOpcode() == ISD::ADD && N0.hasOneUse() && isAllOnesConstant(N1) &&
      isAllOnesOrAllOnesSplat(N0.getOperand(1))) {
```

https://github.com/llvm/llvm-project/pull/126667