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Turn div X, (Cond ? Y : 0) -> div X, Y

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This implements select.ll::test18.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30230 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-09-09 20:26:32 +00:00
parent bbf4636200
commit 8e49e08f4b
1 changed files with 68 additions and 19 deletions
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87
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -1894,19 +1894,42 @@ Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
}
}
// If this is 'udiv X, (Cond ? C1, C2)' where C1&C2 are powers of two,
// transform this into: '(Cond ? (udiv X, C1) : (udiv X, C2))'.
if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
// Handle div X, Cond?Y:Z
if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
// div X, (Cond ? 0 : Y) -> div X, Y. If the div and the select are in the
// same basic block, then we replace the select with Y, and the condition of
// the select with false (if the cond value is in the same BB). If the
// select has uses other than the div, this allows them to be simplified
// also.
if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
if (ST->isNullValue()) {
Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
if (CondI && CondI->getParent() == I.getParent())
UpdateValueUsesWith(CondI, ConstantBool::False);
else if (I.getParent() != SI->getParent() || SI->hasOneUse())
I.setOperand(1, SI->getOperand(2));
else
UpdateValueUsesWith(SI, SI->getOperand(2));
return &I;
}
// Likewise for: div X, (Cond ? Y : 0) -> div X, Y
if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
if (ST->isNullValue()) {
Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
if (CondI && CondI->getParent() == I.getParent())
UpdateValueUsesWith(CondI, ConstantBool::True);
else if (I.getParent() != SI->getParent() || SI->hasOneUse())
I.setOperand(1, SI->getOperand(1));
else
UpdateValueUsesWith(SI, SI->getOperand(1));
return &I;
}
// If this is 'udiv X, (Cond ? C1, C2)' where C1&C2 are powers of two,
// transform this into: '(Cond ? (udiv X, C1) : (udiv X, C2))'.
if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
if (STO->getValue() == 0) { // Couldn't be this argument.
I.setOperand(1, SFO);
return &I;
} else if (SFO->getValue() == 0) {
I.setOperand(1, STO);
return &I;
}
// STO == 0 and SFO == 0 handled above.
uint64_t TVA = STO->getValue(), FVA = SFO->getValue();
if (isPowerOf2_64(TVA) && isPowerOf2_64(FVA)) {
unsigned TSA = Log2_64(TVA), FSA = Log2_64(FVA);
@ -1922,6 +1945,7 @@ Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
return new SelectInst(SI->getOperand(0), TSI, FSI);
}
}
}
// 0 / X == 0, we don't need to preserve faults!
if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
@ -2095,16 +2119,40 @@ Instruction *InstCombiner::visitRem(BinaryOperator &I) {
// If this is 'urem X, (Cond ? C1, C2)' where C1&C2 are powers of two,
// transform this into: '(Cond ? (urem X, C1) : (urem X, C2))'.
if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
// rem X, (Cond ? 0 : Y) -> rem X, Y. If the rem and the select are in
// the same basic block, then we replace the select with Y, and the
// condition of the select with false (if the cond value is in the same
// BB). If the select has uses other than the div, this allows them to be
// simplified also.
if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
if (ST->isNullValue()) {
Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
if (CondI && CondI->getParent() == I.getParent())
UpdateValueUsesWith(CondI, ConstantBool::False);
else if (I.getParent() != SI->getParent() || SI->hasOneUse())
I.setOperand(1, SI->getOperand(2));
else
UpdateValueUsesWith(SI, SI->getOperand(2));
return &I;
}
// Likewise for: rem X, (Cond ? Y : 0) -> rem X, Y
if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
if (ST->isNullValue()) {
Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
if (CondI && CondI->getParent() == I.getParent())
UpdateValueUsesWith(CondI, ConstantBool::True);
else if (I.getParent() != SI->getParent() || SI->hasOneUse())
I.setOperand(1, SI->getOperand(1));
else
UpdateValueUsesWith(SI, SI->getOperand(1));
return &I;
}
if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
if (STO->getValue() == 0) { // Couldn't be this argument.
I.setOperand(1, SFO);
return &I;
} else if (SFO->getValue() == 0) {
I.setOperand(1, STO);
return &I;
}
// STO == 0 and SFO == 0 handled above.
if (isPowerOf2_64(STO->getValue()) && isPowerOf2_64(SFO->getValue())){
Value *TrueAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
@ -2114,6 +2162,7 @@ Instruction *InstCombiner::visitRem(BinaryOperator &I) {
return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
}
}
}
}
return 0;