[llvm] [DAG] fold avgu(zext(x), zext(y)) -> zext(avgu(x, y)) (PR #95134)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-selectiondag

Author: None (c8ef)

<details>
<summary>Changes</summary>

close: #<!-- -->86301

---
Full diff: https://github.com/llvm/llvm-project/pull/95134.diff


1 Files Affected:

- (modified) llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (+15) 


``````````diff
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 4fcbe08e4b2b9..0a78803357410 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -5236,6 +5236,21 @@ SDValue DAGCombiner::visitAVG(SDNode *N) {
     return DAG.getNode(ISD::SRL, DL, VT, X,
                        DAG.getShiftAmountConstant(1, VT, DL));
 
+  // fold avgu(zext(x), zext(y)) -> zext(avgu(x, y))
+  SDValue A;
+  SDValue B;
+  if (hasOperation(ISD::AVGFLOORU, VT) &&
+      sd_match(N, m_c_BinOp(ISD::AVGFLOORU, m_ZExt(m_Value(A)),
+                            m_ZExt(m_Value(B))))) {
+    SDValue AvgFloorU = DAG.getNode(ISD::AVGFLOORU, DL, A.getValueType(), A, B);
+    return DAG.getNode(ISD::ZERO_EXTEND, DL, VT, AvgFloorU);
+  }
+  if (hasOperation(ISD::AVGCEILU, VT) &&
+      sd_match(N, m_c_BinOp(ISD::AVGCEILU, m_ZExt(m_Value(A)),
+                            m_ZExt(m_Value(B))))) {
+    SDValue AvgCeilU = DAG.getNode(ISD::AVGCEILU, DL, A.getValueType(), A, B);
+    return DAG.getNode(ISD::ZERO_EXTEND, DL, VT, AvgCeilU);
+  }
   return SDValue();
 }
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/95134