[llvm-branch-commits] [llvm] [SelectionDAG] Drop unnecessary lower bound check in lowerRangeToAssertZExt (PR #196785)

[Iris Shi via llvm-branch-commits]

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@@ -16213,6 +16213,10 @@ SDValue DAGCombiner::visitAssertExt(SDNode *N) {
       AssertVT == cast<VTSDNode>(N0.getOperand(1))->getVT())
     return N0;
 
+  // fold (assert?ext c, vt) -> c
+  if (isa<ConstantSDNode>(N0))
+    return N0;
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el-ev wrote:

It would still need a call to `DAG.FoldConstantArithmetic` here, neither cleaner nor cheaper.

https://github.com/llvm/llvm-project/pull/196785