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| author | Dan Gohman <gohman@apple.com> | 2009-08-12 16:33:09 +0000 |
|---|---|---|
| committer | Dan Gohman <gohman@apple.com> | 2009-08-12 16:33:09 +0000 |
| commit | fa94b948d9a0aaaad98901815e56b676803ad259 (patch) | |
| tree | fe5f5ff724d6bd1e9a39ed0c49b4d4148856e70d /lib/Transforms/Scalar | |
| parent | 2df6e6467f679984e98612e695682fcc834bd95f (diff) | |
| download | external_llvm-fa94b948d9a0aaaad98901815e56b676803ad259.zip external_llvm-fa94b948d9a0aaaad98901815e56b676803ad259.tar.gz external_llvm-fa94b948d9a0aaaad98901815e56b676803ad259.tar.bz2 | |
Optimize (x/C)*C to x if the division is exact.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78811 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms/Scalar')
| -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 514e91b..669ef2d 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()) { |