[PATCH] D137170: [PatternMatch] don't match a scalar select of bool vectors as a logical-and or logical-or

[Sanjay Patel via Phabricator via llvm-commits]

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Most folds based on these matchers already check to make sure the condition type is the same as the select type, and it seems unlikely that a fold would want to handle a scalar-select-of-vectors pattern (there are no regression tests for it).

This is a preliminary step for fixing #issue 58552 <https://github.com/llvm/llvm-project/issues/58552>. The fold(s) responsible for that crash (D101807 <https://reviews.llvm.org/D101807>, D101375 <https://reviews.llvm.org/D101375>) don't use the matchers yet, but they probably should.


https://reviews.llvm.org/D137170

Files:
  llvm/include/llvm/IR/PatternMatch.h
  llvm/unittests/IR/PatternMatch.cpp


Index: llvm/unittests/IR/PatternMatch.cpp
===================================================================
--- llvm/unittests/IR/PatternMatch.cpp
+++ llvm/unittests/IR/PatternMatch.cpp
@@ -1730,10 +1730,12 @@
   // select i1 Scalar, <3 x i1> <i1 1, i1 1, i1 1>, <3 x i1> Vector
   Value *MixedTypeOr = IRB.CreateSelect(Scalar, T, Vector);
 
+  // We allow matching a real vector logical select,
+  // but not a scalar select of vector bools.
   EXPECT_TRUE(match(VecAnd, m_LogicalAnd(m_Value(), m_Value())));
-  EXPECT_TRUE(match(MixedTypeAnd, m_LogicalAnd(m_Value(), m_Value())));
+  EXPECT_FALSE(match(MixedTypeAnd, m_LogicalAnd(m_Value(), m_Value())));
   EXPECT_TRUE(match(VecOr, m_LogicalOr(m_Value(), m_Value())));
-  EXPECT_TRUE(match(MixedTypeOr, m_LogicalOr(m_Value(), m_Value())));
+  EXPECT_FALSE(match(MixedTypeOr, m_LogicalOr(m_Value(), m_Value())));
 }
 
 TEST_F(PatternMatchTest, VScale) {
Index: llvm/include/llvm/IR/PatternMatch.h
===================================================================
--- llvm/include/llvm/IR/PatternMatch.h
+++ llvm/include/llvm/IR/PatternMatch.h
@@ -2513,6 +2513,12 @@
       auto *Cond = Select->getCondition();
       auto *TVal = Select->getTrueValue();
       auto *FVal = Select->getFalseValue();
+
+      // Don't match a scalar select of bool vectors.
+      // Transforms expect a single type for operands if this matches.
+      if (Cond->getType() != Select->getType())
+        return false;
+
       if (Opcode == Instruction::And) {
         auto *C = dyn_cast<Constant>(FVal);
         if (C && C->isNullValue())


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