diff options
Diffstat (limited to 'llvm/lib/IR/ConstantFold.cpp')
| -rw-r--r-- | llvm/lib/IR/ConstantFold.cpp | 27 |
1 files changed, 14 insertions, 13 deletions
diff --git a/llvm/lib/IR/ConstantFold.cpp b/llvm/lib/IR/ConstantFold.cpp index cd409083afc..49ef3024033 100644 --- a/llvm/lib/IR/ConstantFold.cpp +++ b/llvm/lib/IR/ConstantFold.cpp @@ -951,21 +951,22 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, return C1; return Constant::getAllOnesValue(C1->getType()); // undef | X -> ~0 case Instruction::LShr: - if (isa<UndefValue>(C2) && isa<UndefValue>(C1)) - return C1; // undef lshr undef -> undef - return Constant::getNullValue(C1->getType()); // X lshr undef -> 0 - // undef lshr X -> 0 + // X >>l undef -> undef + if (isa<UndefValue>(C2)) + return C2; + // undef >>l X -> 0 + return Constant::getNullValue(C1->getType()); case Instruction::AShr: - if (!isa<UndefValue>(C2)) // undef ashr X --> all ones - return Constant::getAllOnesValue(C1->getType()); - else if (isa<UndefValue>(C1)) - return C1; // undef ashr undef -> undef - else - return C1; // X ashr undef --> X + // X >>a undef -> undef + if (isa<UndefValue>(C2)) + return C2; + // undef >>a X -> all ones + return Constant::getAllOnesValue(C1->getType()); case Instruction::Shl: - if (isa<UndefValue>(C2) && isa<UndefValue>(C1)) - return C1; // undef shl undef -> undef - // undef << X -> 0 or X << undef -> 0 + // X << undef -> undef + if (isa<UndefValue>(C2)) + return C2; + // undef << X -> 0 return Constant::getNullValue(C1->getType()); } } |
