diff options
Diffstat (limited to 'lib/Transforms/Scalar/InstructionCombining.cpp')
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 514e91bdef..669ef2d516 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -2701,6 +2701,15 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { BO->getOpcode() == Instruction::SDiv)) { Value *Op0BO = BO->getOperand(0), *Op1BO = BO->getOperand(1); + // If the division is exact, X % Y is zero. + if (SDivOperator *SDiv = dyn_cast<SDivOperator>(BO)) + if (SDiv->isExact()) { + if (Op1BO == Op1) + return ReplaceInstUsesWith(I, Op0BO); + else + return BinaryOperator::CreateNeg(Op0BO); + } + Instruction *Rem; if (BO->getOpcode() == Instruction::UDiv) Rem = BinaryOperator::CreateURem(Op0BO, Op1BO); @@ -3060,7 +3069,7 @@ Instruction *InstCombiner::visitSDiv(BinaryOperator &I) { if (RHS->isAllOnesValue()) return BinaryOperator::CreateNeg(Op0); - // sdiv X, C --> ashr X, log2(C) + // sdiv X, C --> ashr X, log2(C) if (cast<SDivOperator>(&I)->isExact() && RHS->getValue().isNonNegative() && RHS->getValue().isPowerOf2()) { |