6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-07-24 22:24:54 +00:00
Code Issues Projects Releases Wiki Activity

Optimize (x/C)*C to x if the division is exact.

Browse Source 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78811 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
2009-08-12 16:33:09 +00:00
parent 2df6e6467f
commit fa94b948d9
2 changed files with 47 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@@ -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()) {