[PATCH] D132206: [DAGCombiner] Fold vecreduce_xor/or/and(splat_vector(val)) to constant

[WangLian via Phabricator via llvm-commits]

Jimerlife created this revision.
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fold vecreduce_or/and(splat_vector(val)) -> constant val
fold vecreduce_xor(splat_vector(val)) -> constant zero


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D132206

Files:
  llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp


Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -23498,6 +23498,16 @@
       return DAG.getNode(Opcode, SDLoc(N), N->getValueType(0), Subvec);
   }
 
+  // fold vecreduce_or/and(splat_vector(val)) -> constant val
+  // fold vecreduce_xor(splat_vector(val)) -> constant zero
+  APInt SplatVal;
+  if (ISD::isConstantSplatVector(N0.getNode(), SplatVal)) {
+    if (Opcode == ISD::VECREDUCE_XOR)
+      return DAG.getConstant(0, SDLoc(N), N->getValueType(0));
+    if (Opcode == ISD::VECREDUCE_AND || Opcode == ISD::VECREDUCE_OR)
+      return DAG.getConstant(SplatVal, SDLoc(N), N->getValueType(0));
+  }
+
   return SDValue();
 }
 


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