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Remove OptimizeIVType()

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@55913 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel 2008-09-08 16:13:27 +00:00
parent 28f02128ae
commit 175f9d94db
1 changed files with 0 additions and 206 deletions
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206
lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -185,10 +185,6 @@ private:
/// inside the loop then try to eliminate the cast opeation.
void OptimizeShadowIV(Loop *L);
/// OptimizeIVType - If IV is always sext'ed or zext'ed then
/// change the type of IV, if possible.
void OptimizeIVType(Loop *L);
bool FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse,
const SCEVHandle *&CondStride);
bool RequiresTypeConversion(const Type *Ty, const Type *NewTy);
@ -1813,206 +1809,6 @@ void LoopStrengthReduce::OptimizeShadowIV(Loop *L) {
}
}
/// suitableExtInstruction - Helper function used by OptimizeIVType.
/// If I is a suitable SEXT or ZEXT instruction then return type
/// to which I is extended to. Otherwise return NULL.
const Type *suitableExtInstruction(Instruction *I, bool isSigned,
const Type *ExtType) {
const Type *DestType = NULL;
if (ZExtInst *ZI = dyn_cast<ZExtInst>(I))
DestType = ZI->getDestTy();
else if (SExtInst *SI = dyn_cast<SExtInst>(I)) {
// If the inital value is signed then this is not suitable for
// OptimizeIVType transformation.
if (isSigned)
return NULL;
DestType = SI->getDestTy();
}
if (!DestType) return NULL;
if (!ExtType)
return DestType;
// If another use of IV extended to some other type then the IV is not
// suitable for OptimizeIVType transformation.
if (ExtType != DestType)
return NULL;
return DestType;
}
/// suitableIVIncr - Helper function used by OptimizeIVType. If I is
/// a suitable binary operator whose all uses are either SEXT or ZEXT
/// then return the type to which all uses are extended to. Otherwise
/// return NULL.
const Type *suitableIVIncr(Instruction *I,
Instruction *PHI, bool isSigned,
const Type *ExtType) {
BinaryOperator *Incr = dyn_cast<BinaryOperator>(I);
if (!Incr) return NULL;
if (Incr->getOpcode() != Instruction::Add)
return NULL;
ConstantInt *C = NULL;
if (Incr->getOperand(0) == PHI)
C = dyn_cast<ConstantInt>(Incr->getOperand(1));
else if (Incr->getOperand(1) == PHI)
C = dyn_cast<ConstantInt>(Incr->getOperand(0));
if (!C) return NULL;
const Type *RExtType = NULL;
for (Value::use_iterator IncUI = Incr->use_begin(),
IncUE = Incr->use_end(); IncUI != IncUE; ++IncUI) {
Instruction *U2 = dyn_cast<Instruction>(*IncUI);
if (U2 == PHI)
continue;
const Type *DestType = suitableExtInstruction(U2, isSigned, ExtType);
if (!DestType)
return NULL;
if (!RExtType)
RExtType = DestType;
if (DestType != RExtType)
return NULL;
}
return RExtType;
}
/// getNewPHIIncrement - Create a new increment instruction for newPHI
/// using type Ty based on increment instruction Incr.
/// Helper function used by OptimizeIVType.
BinaryOperator *getNewPHIIncrement(BinaryOperator *Incr, PHINode *PHI,
PHINode *NewPHI, const Type *Ty) {
ConstantInt *C = NULL;
if (Incr->getOperand(0) == PHI)
C = dyn_cast<ConstantInt>(Incr->getOperand(1));
else if (Incr->getOperand(1) == PHI)
C = dyn_cast<ConstantInt>(Incr->getOperand(0));
assert (C && "Unexpected Incr operand!");
return BinaryOperator::Create(Incr->getOpcode(), NewPHI,
ConstantInt::get(Ty, C->getZExtValue()),
"IV.next", Incr);
}
/// OptimizeIVType - If IV is always sext'ed or zext'ed then
/// change the type of IV, if possible.
void LoopStrengthReduce::OptimizeIVType(Loop *L) {
SCEVHandle IterationCount = SE->getIterationCount(L);
if (isa<SCEVCouldNotCompute>(IterationCount))
return;
BasicBlock *LPH = L->getLoopPreheader();
BasicBlock *LatchBB = L->getLoopLatch();
SmallVector<PHINode *, 4> PHIs;
for (BasicBlock::iterator BI = L->getHeader()->begin(),
BE = L->getHeader()->end(); BI != BE; ++BI) {
if (PHINode *PHI = dyn_cast<PHINode>(BI))
PHIs.push_back(PHI);
else
break;
}
while(!PHIs.empty()) {
PHINode *PHI = PHIs.back(); PHIs.pop_back();
if (PHI->getNumIncomingValues() != 2) continue;
unsigned Entry = 0, Latch = 1;
if (PHI->getIncomingBlock(0) != LPH) {
Entry = 1;
Latch = 0;
}
ConstantInt *CInit = dyn_cast<ConstantInt>(PHI->getIncomingValue(Entry));
if (!CInit) return;
if (!CInit->isZero()) return;
bool signedInit = CInit->getValue().isNegative();
bool TransformPhi = true;
const Type *ExtType = NULL;
BinaryOperator *Incr = NULL;
SmallVector<Instruction *, 4> PHIUses;
// Collect all IV uses.
for (Value::use_iterator UI = PHI->use_begin(),
UE = PHI->use_end(); UI != UE; ++UI) {
Instruction *Use = dyn_cast<Instruction>(*UI);
if (!Use) {
TransformPhi = false;
break;
}
ExtType = suitableIVIncr(Use, PHI, signedInit, ExtType);
if (ExtType) {
Incr = cast<BinaryOperator>(Use);
continue;
}
ExtType = suitableExtInstruction(Use, signedInit, ExtType);
if (ExtType) {
PHIUses.push_back(Use);
continue;
}
TransformPhi = false;
break;
}
if (!TransformPhi || Incr == false || PHIUses.empty())
continue;
// Apply transformation. Extend IV type and eliminate SEXT or ZEXT
// instructions.
NumIVType++;
PHINode *NewPH = PHINode::Create(ExtType, "IV", PHI);
ConstantInt *NewCInit = ConstantInt::get(ExtType, CInit->getZExtValue());
BinaryOperator *NewIncr = getNewPHIIncrement(Incr, PHI, NewPH, ExtType);
NewPH->addIncoming(NewCInit, PHI->getIncomingBlock(Entry));
NewPH->addIncoming(NewIncr, PHI->getIncomingBlock(Latch));
// Replace all SEXT or ZEXT uses with new IV directly.
while (!PHIUses.empty()) {
Instruction *Use = PHIUses.back(); PHIUses.pop_back();
SE->deleteValueFromRecords(Use);
Use->replaceAllUsesWith(NewPH);
Use->eraseFromParent();
}
// Replace all uses of IV increment with new increment.
SmallVector<Instruction *, 2> IncrUses;
for (Value::use_iterator UI2 = Incr->use_begin(),
UE2 = Incr->use_end(); UI2 != UE2; ++UI2)
IncrUses.push_back(cast<Instruction>(*UI2));
while (!IncrUses.empty()) {
Instruction *Use = IncrUses.back(); IncrUses.pop_back();
if (Use == PHI) continue;
SE->deleteValueFromRecords(Use);
Use->replaceAllUsesWith(NewIncr);
Use->eraseFromParent();
}
// Remove old PHI and increment instruction.
SE->deleteValueFromRecords(PHI);
PHI->removeIncomingValue(LatchBB);
PHI->removeIncomingValue(LPH);
SE->deleteValueFromRecords(Incr);
Incr->eraseFromParent();
}
}
// OptimizeIndvars - Now that IVUsesByStride is set up with all of the indvar
// uses in the loop, look to see if we can eliminate some, in favor of using
// common indvars for the different uses.
@ -2082,8 +1878,6 @@ bool LoopStrengthReduce::runOnLoop(Loop *L, LPPassManager &LPM) {
UIntPtrTy = TD->getIntPtrType();
Changed = false;
OptimizeIVType(L);
// Find all uses of induction variables in this loop, and catagorize
// them by stride. Start by finding all of the PHI nodes in the header for
// this loop. If they are induction variables, inspect their uses.