[llvm] [SelectionDAG] Preserver poison for abs INT_MIN lowering (PR #183851)

[Matt Arsenault via llvm-commits]

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@@ -11942,6 +11946,28 @@ SDValue DAGCombiner::visitABS(SDNode *N) {
   return SDValue();
 }
 
+SDValue DAGCombiner::visitABS_MIN_POISON(SDNode *N) {
+  SDValue N0 = N->getOperand(0);
+  EVT VT = N->getValueType(0);
+  SDLoc DL(N);
+
+  // fold (abs_min_poison c1) -> c2
+  if (SDValue C = DAG.FoldConstantArithmetic(ISD::ABS, DL, VT, {N0}))
+    return C;
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arsenm wrote:

This won't fold the poison case to poison

https://github.com/llvm/llvm-project/pull/183851