[llvm] [DAGCombiner] Strip outer match in visitBITREVERSE (NFC) (PR #169020)
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Fri Nov 21 01:10:35 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-selectiondag
Author: Ramkumar Ramachandra (artagnon)
<details>
<summary>Changes</summary>
---
Full diff: https://github.com/llvm/llvm-project/pull/169020.diff
1 Files Affected:
- (modified) llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (+2-2)
``````````diff
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 94afdc5db6613..6c9a0ba4be07f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -11763,12 +11763,12 @@ SDValue DAGCombiner::visitBITREVERSE(SDNode *N) {
// fold (bitreverse (lshr (bitreverse x), y)) -> (shl x, y)
if ((!LegalOperations || TLI.isOperationLegal(ISD::SHL, VT)) &&
- sd_match(N, m_BitReverse(m_Srl(m_BitReverse(m_Value(X)), m_Value(Y)))))
+ sd_match(N0, m_Srl(m_BitReverse(m_Value(X)), m_Value(Y))))
return DAG.getNode(ISD::SHL, DL, VT, X, Y);
// fold (bitreverse (shl (bitreverse x), y)) -> (lshr x, y)
if ((!LegalOperations || TLI.isOperationLegal(ISD::SRL, VT)) &&
- sd_match(N, m_BitReverse(m_Shl(m_BitReverse(m_Value(X)), m_Value(Y)))))
+ sd_match(N0, m_Shl(m_BitReverse(m_Value(X)), m_Value(Y))))
return DAG.getNode(ISD::SRL, DL, VT, X, Y);
return SDValue();
``````````
</details>
https://github.com/llvm/llvm-project/pull/169020
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