[SDAG] enable binop identity constant folds for multiplies

Add mul to the list of ops that we canonicalize with a select to expose an identity merge Differential Revision: https://reviews.llvm.org/D122071
llvm · Mar 25, 2022 · e209190 · e209190
1 parent 8639bc1
commit e209190
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diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -2167,6 +2167,8 @@ static SDValue foldSelectWithIdentityConstant(SDNode *N, SelectionDAG &DAG,
       case ISD::SRA: // X s>> 0 --> X
       case ISD::SRL: // X u>> 0 --> X
         return C->isZero();
+      case ISD::MUL: // X * 1 --> X
+        return C->isOne();
       }
     }
     return false;