diff options
Diffstat (limited to 'llvm/lib/Analysis')
| -rw-r--r-- | llvm/lib/Analysis/InstructionSimplify.cpp | 14 |
1 files changed, 3 insertions, 11 deletions
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp index f151a3a33b4..7cbe6eff4ba 100644 --- a/llvm/lib/Analysis/InstructionSimplify.cpp +++ b/llvm/lib/Analysis/InstructionSimplify.cpp @@ -683,17 +683,9 @@ static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, if (Op0 == Op1) return Constant::getNullValue(Op0->getType()); - // X - (0 - Y) -> X if the second sub is NUW. - // If Y != 0, 0 - Y is a poison value. - // If Y == 0, 0 - Y simplifies to 0. - if (BinaryOperator::isNeg(Op1)) { - if (const auto *BO = dyn_cast<BinaryOperator>(Op1)) { - assert(BO->getOpcode() == Instruction::Sub && - "Expected a subtraction operator!"); - if (BO->hasNoUnsignedWrap()) - return Op0; - } - } + // 0 - X -> 0 if the sub is NUW. + if (isNUW && match(Op0, m_Zero())) + return Op0; // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies. // For example, (X + Y) - Y -> X; (Y + X) - Y -> X |
