[llvm] abbef2f - [ValueTracking] isGuaranteedNotToBePoison should return true on undef

[Juneyoung Lee via llvm-commits]

Author: Juneyoung Lee
Date: 2021-01-05T06:50:02+09:00
New Revision: abbef2fd46d48a0d92d86f0c00fa2973f8ae2c85

URL: https://github.com/llvm/llvm-project/commit/abbef2fd46d48a0d92d86f0c00fa2973f8ae2c85
DIFF: https://github.com/llvm/llvm-project/commit/abbef2fd46d48a0d92d86f0c00fa2973f8ae2c85.diff

LOG: [ValueTracking] isGuaranteedNotToBePoison should return true on undef

This is a one-line fix to isGuaranteedNotToBePoison to return true if
undef is given.

Added: 
    

Modified: 
    llvm/lib/Analysis/ValueTracking.cpp
    llvm/unittests/Analysis/ValueTrackingTest.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 303240d03c72..e15d4f0e4b07 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4888,7 +4888,7 @@ static bool isGuaranteedNotToBeUndefOrPoison(const Value *V,
 
   if (auto *C = dyn_cast<Constant>(V)) {
     if (isa<UndefValue>(C))
-      return PoisonOnly;
+      return PoisonOnly && !isa<PoisonValue>(C);
 
     if (isa<ConstantInt>(C) || isa<GlobalVariable>(C) || isa<ConstantFP>(V) ||
         isa<ConstantPointerNull>(C) || isa<Function>(C))

diff  --git a/llvm/unittests/Analysis/ValueTrackingTest.cpp b/llvm/unittests/Analysis/ValueTrackingTest.cpp
index 009166a24a1f..0d6577452560 100644
--- a/llvm/unittests/Analysis/ValueTrackingTest.cpp
+++ b/llvm/unittests/Analysis/ValueTrackingTest.cpp
@@ -884,6 +884,10 @@ TEST_F(ValueTrackingTest, isGuaranteedNotToBeUndefOrPoison) {
                 "  ret void\n"
                 "}\n");
   EXPECT_EQ(isGuaranteedNotToBeUndefOrPoison(A), true);
+  EXPECT_EQ(isGuaranteedNotToBeUndefOrPoison(UndefValue::get(IntegerType::get(Context, 8))), false);
+  EXPECT_EQ(isGuaranteedNotToBeUndefOrPoison(PoisonValue::get(IntegerType::get(Context, 8))), false);
+  EXPECT_EQ(isGuaranteedNotToBePoison(UndefValue::get(IntegerType::get(Context, 8))), true);
+  EXPECT_EQ(isGuaranteedNotToBePoison(PoisonValue::get(IntegerType::get(Context, 8))), false);
 }
 
 TEST_F(ValueTrackingTest, isGuaranteedNotToBeUndefOrPoison_assume) {