diff options
| -rw-r--r-- | llvm/lib/Analysis/InstructionSimplify.cpp | 8 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstSimplify/undef.ll | 14 |
2 files changed, 20 insertions, 2 deletions
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp index 767b42b4bd7..1c5a917cbec 100644 --- a/llvm/lib/Analysis/InstructionSimplify.cpp +++ b/llvm/lib/Analysis/InstructionSimplify.cpp @@ -1387,8 +1387,10 @@ static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, return V; // undef >>l X -> 0 + // undef >>l X -> undef (if it's exact) if (match(Op0, m_Undef())) - return Constant::getNullValue(Op0->getType()); + return isExact ? UndefValue::get(Op0->getType()) + : Constant::getNullValue(Op0->getType()); // (X << A) >> A -> X Value *X; @@ -1421,8 +1423,10 @@ static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, return Op0; // undef >>a X -> all ones + // undef >>a X -> undef (if it's exact) if (match(Op0, m_Undef())) - return Constant::getAllOnesValue(Op0->getType()); + return isExact ? UndefValue::get(Op0->getType()) + : Constant::getAllOnesValue(Op0->getType()); // (X << A) >> A -> X Value *X; diff --git a/llvm/test/Transforms/InstSimplify/undef.ll b/llvm/test/Transforms/InstSimplify/undef.ll index a6ae7a9fbf7..3742d7450af 100644 --- a/llvm/test/Transforms/InstSimplify/undef.ll +++ b/llvm/test/Transforms/InstSimplify/undef.ll @@ -174,3 +174,17 @@ define i32 @test21(i32 %a) { %b = sdiv i32 %a, 0 ret i32 %b } + +; CHECK-LABEL: @test22 +; CHECK: ret i32 undef +define i32 @test22(i32 %a) { + %b = ashr exact i32 undef, %a + ret i32 %b +} + +; CHECK-LABEL: @test23 +; CHECK: ret i32 undef +define i32 @test23(i32 %a) { + %b = lshr exact i32 undef, %a + ret i32 %b +} |
