[llvm] c1e159e - [IR] fix Constant::isElementWiseEqual() to allow for all undef elements compare

[Sanjay Patel via llvm-commits]

Author: Sanjay Patel
Date: 2020-01-17T08:31:16-05:00
New Revision: c1e159ef6eb0095b78d08594f02f511c69d9a64b

URL: https://github.com/llvm/llvm-project/commit/c1e159ef6eb0095b78d08594f02f511c69d9a64b
DIFF: https://github.com/llvm/llvm-project/commit/c1e159ef6eb0095b78d08594f02f511c69d9a64b.diff

LOG: [IR] fix Constant::isElementWiseEqual() to allow for all undef elements compare

We could argue that match() should be more flexible here,
but I'm not sure what impact that would have on existing code.

Added: 
    

Modified: 
    llvm/lib/IR/Constants.cpp
    llvm/unittests/IR/ConstantsTest.cpp

Removed: 
    


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diff  --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index 93d406fa2eb0..79c302867369 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -296,7 +296,8 @@ bool Constant::isElementWiseEqual(Value *Y) const {
   Type *IntTy = VectorType::getInteger(cast<VectorType>(Ty));
   Constant *C0 = ConstantExpr::getBitCast(const_cast<Constant *>(this), IntTy);
   Constant *C1 = ConstantExpr::getBitCast(cast<Constant>(Y), IntTy);
-  return match(ConstantExpr::getICmp(ICmpInst::ICMP_EQ, C0, C1), m_One());
+  Constant *CmpEq = ConstantExpr::getICmp(ICmpInst::ICMP_EQ, C0, C1);
+  return isa<UndefValue>(CmpEq) || match(CmpEq, m_One());
 }
 
 bool Constant::containsUndefElement() const {

diff  --git a/llvm/unittests/IR/ConstantsTest.cpp b/llvm/unittests/IR/ConstantsTest.cpp
index 7154f35ccbd4..5b5e8d154c21 100644
--- a/llvm/unittests/IR/ConstantsTest.cpp
+++ b/llvm/unittests/IR/ConstantsTest.cpp
@@ -620,7 +620,7 @@ TEST(ConstantsTest, isElementWiseEqual) {
 
   EXPECT_TRUE(CF1211->isElementWiseEqual(CF12U1));
   EXPECT_TRUE(CF12U1->isElementWiseEqual(CF1211));
-  EXPECT_FALSE(CFUU1U->isElementWiseEqual(CF12U1)); // FIXME - all lanes compare as undef
+  EXPECT_TRUE(CFUU1U->isElementWiseEqual(CF12U1));
   EXPECT_FALSE(CF12U2->isElementWiseEqual(CF12U1));
   EXPECT_FALSE(CF12U1->isElementWiseEqual(CF12U2));