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split load sinking out to its own function, like gep sinking.

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llvm-svn: 85737
This commit is contained in:
Chris Lattner 2009-11-01 20:04:24 +00:00
parent b3fe1009a5
commit e7b1e067e9
1 changed files with 101 additions and 66 deletions
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167
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -416,6 +416,7 @@ namespace {
Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN);
Instruction *FoldPHIArgLoadIntoPHI(PHINode &PN);
Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
@ -10731,6 +10732,96 @@ static bool isSafeAndProfitableToSinkLoad(LoadInst *L) {
return true;
}
Instruction *InstCombiner::FoldPHIArgLoadIntoPHI(PHINode &PN) {
LoadInst *FirstLI = cast<LoadInst>(PN.getIncomingValue(0));
// When processing loads, we need to propagate two bits of information to the
// sunk load: whether it is volatile, and what its alignment is. We currently
// don't sink loads when some have their alignment specified and some don't.
// visitLoadInst will propagate an alignment onto the load when TD is around,
// and if TD isn't around, we can't handle the mixed case.
bool isVolatile = FirstLI->isVolatile();
unsigned LoadAlignment = FirstLI->getAlignment();
// We can't sink the load if the loaded value could be modified between the
// load and the PHI.
if (FirstLI->getParent() != PN.getIncomingBlock(0) ||
!isSafeAndProfitableToSinkLoad(FirstLI))
return 0;
// If the PHI is of volatile loads and the load block has multiple
// successors, sinking it would remove a load of the volatile value from
// the path through the other successor.
if (isVolatile &&
FirstLI->getParent()->getTerminator()->getNumSuccessors() != 1)
return 0;
// Check to see if all arguments are the same operation.
for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
LoadInst *LI = dyn_cast<LoadInst>(PN.getIncomingValue(i));
if (!LI || !LI->hasOneUse())
return 0;
// We can't sink the load if the loaded value could be modified between
// the load and the PHI.
if (LI->isVolatile() != isVolatile ||
LI->getParent() != PN.getIncomingBlock(i) ||
!isSafeAndProfitableToSinkLoad(LI))
return 0;
// If some of the loads have an alignment specified but not all of them,
// we can't do the transformation.
if ((LoadAlignment != 0) != (LI->getAlignment() != 0))
return 0;
LoadAlignment = std::max(LoadAlignment, LI->getAlignment());
// If the PHI is of volatile loads and the load block has multiple
// successors, sinking it would remove a load of the volatile value from
// the path through the other successor.
if (isVolatile &&
LI->getParent()->getTerminator()->getNumSuccessors() != 1)
return 0;
}
// Okay, they are all the same operation. Create a new PHI node of the
// correct type, and PHI together all of the LHS's of the instructions.
PHINode *NewPN = PHINode::Create(FirstLI->getOperand(0)->getType(),
PN.getName()+".in");
NewPN->reserveOperandSpace(PN.getNumOperands()/2);
Value *InVal = FirstLI->getOperand(0);
NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
// Add all operands to the new PHI.
for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
Value *NewInVal = cast<LoadInst>(PN.getIncomingValue(i))->getOperand(0);
if (NewInVal != InVal)
InVal = 0;
NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
}
Value *PhiVal;
if (InVal) {
// The new PHI unions all of the same values together. This is really
// common, so we handle it intelligently here for compile-time speed.
PhiVal = InVal;
delete NewPN;
} else {
InsertNewInstBefore(NewPN, PN);
PhiVal = NewPN;
}
// If this was a volatile load that we are merging, make sure to loop through
// and mark all the input loads as non-volatile. If we don't do this, we will
// insert a new volatile load and the old ones will not be deletable.
if (isVolatile)
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
cast<LoadInst>(PN.getIncomingValue(i))->setVolatile(false);
return new LoadInst(PhiVal, "", isVolatile, LoadAlignment);
}
// FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
// operator and they all are only used by the PHI, PHI together their
@ -10738,6 +10829,11 @@ static bool isSafeAndProfitableToSinkLoad(LoadInst *L) {
Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
if (isa<GetElementPtrInst>(FirstInst))
return FoldPHIArgGEPIntoPHI(PN);
if (isa<LoadInst>(FirstInst))
return FoldPHIArgLoadIntoPHI(PN);
// Scan the instruction, looking for input operations that can be folded away.
// If all input operands to the phi are the same instruction (e.g. a cast from
// the same type or "+42") we can pull the operation through the PHI, reducing
@ -10745,14 +10841,6 @@ Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
Constant *ConstantOp = 0;
const Type *CastSrcTy = 0;
// When processing loads, we need to propagate two bits of information to the
// sunk load: whether it is volatile, and what its alignment is. We currently
// don't sink loads when some have their alignment specified and some don't.
// visitLoadInst will propagate an alignment onto the load when TD is around,
// and if TD isn't around, we can't handle the mixed case.
bool isVolatile = false;
unsigned LoadAlignment = 0;
if (isa<CastInst>(FirstInst)) {
CastSrcTy = FirstInst->getOperand(0)->getType();
} else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) {
@ -10761,61 +10849,18 @@ Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
if (ConstantOp == 0)
return FoldPHIArgBinOpIntoPHI(PN);
} else if (LoadInst *LI = dyn_cast<LoadInst>(FirstInst)) {
isVolatile = LI->isVolatile();
LoadAlignment = LI->getAlignment();
// We can't sink the load if the loaded value could be modified between the
// load and the PHI.
if (LI->getParent() != PN.getIncomingBlock(0) ||
!isSafeAndProfitableToSinkLoad(LI))
return 0;
// If the PHI is of volatile loads and the load block has multiple
// successors, sinking it would remove a load of the volatile value from
// the path through the other successor.
if (isVolatile &&
LI->getParent()->getTerminator()->getNumSuccessors() != 1)
return 0;
} else if (isa<GetElementPtrInst>(FirstInst)) {
return FoldPHIArgGEPIntoPHI(PN);
} else {
return 0; // Cannot fold this operation.
}
// Check to see if all arguments are the same operation.
for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
if (!I->hasOneUse() || !I->isSameOperationAs(FirstInst))
Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
if (I == 0 || !I->hasOneUse() || !I->isSameOperationAs(FirstInst))
return 0;
if (CastSrcTy) {
if (I->getOperand(0)->getType() != CastSrcTy)
return 0; // Cast operation must match.
} else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
// We can't sink the load if the loaded value could be modified between
// the load and the PHI.
if (LI->isVolatile() != isVolatile ||
LI->getParent() != PN.getIncomingBlock(i) ||
!isSafeAndProfitableToSinkLoad(LI))
return 0;
// If some of the loads have an alignment specified but not all of them,
// we can't do the transformation.
if ((LoadAlignment != 0) != (LI->getAlignment() != 0))
return 0;
LoadAlignment = std::max(LoadAlignment, LI->getAlignment());
// If the PHI is of volatile loads and the load block has multiple
// successors, sinking it would remove a load of the volatile value from
// the path through the other successor.
if (isVolatile &&
LI->getParent()->getTerminator()->getNumSuccessors() != 1)
return 0;
} else if (I->getOperand(1) != ConstantOp) {
return 0;
}
@ -10856,19 +10901,9 @@ Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
return BinaryOperator::Create(BinOp->getOpcode(), PhiVal, ConstantOp);
if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
PhiVal, ConstantOp);
assert(isa<LoadInst>(FirstInst) && "Unknown operation");
// If this was a volatile load that we are merging, make sure to loop through
// and mark all the input loads as non-volatile. If we don't do this, we will
// insert a new volatile load and the old ones will not be deletable.
if (isVolatile)
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
cast<LoadInst>(PN.getIncomingValue(i))->setVolatile(false);
return new LoadInst(PhiVal, "", isVolatile, LoadAlignment);
CmpInst *CIOp = cast<CmpInst>(FirstInst);
return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
PhiVal, ConstantOp);
}
/// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle