InstCombinePHI.cpp [plain text]
#include "InstCombine.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/IR/DataLayout.h"
using namespace llvm;
Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) {
Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
assert(isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst));
unsigned Opc = FirstInst->getOpcode();
Value *LHSVal = FirstInst->getOperand(0);
Value *RHSVal = FirstInst->getOperand(1);
Type *LHSType = LHSVal->getType();
Type *RHSType = RHSVal->getType();
bool isNUW = false, isNSW = false, isExact = false;
if (OverflowingBinaryOperator *BO =
dyn_cast<OverflowingBinaryOperator>(FirstInst)) {
isNUW = BO->hasNoUnsignedWrap();
isNSW = BO->hasNoSignedWrap();
} else if (PossiblyExactOperator *PEO =
dyn_cast<PossiblyExactOperator>(FirstInst))
isExact = PEO->isExact();
for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
if (!I || I->getOpcode() != Opc || !I->hasOneUse() ||
I->getOperand(0)->getType() != LHSType ||
I->getOperand(1)->getType() != RHSType)
return 0;
if (CmpInst *CI = dyn_cast<CmpInst>(I))
if (CI->getPredicate() != cast<CmpInst>(FirstInst)->getPredicate())
return 0;
if (isNUW)
isNUW = cast<OverflowingBinaryOperator>(I)->hasNoUnsignedWrap();
if (isNSW)
isNSW = cast<OverflowingBinaryOperator>(I)->hasNoSignedWrap();
if (isExact)
isExact = cast<PossiblyExactOperator>(I)->isExact();
if (I->getOperand(0) != LHSVal) LHSVal = 0;
if (I->getOperand(1) != RHSVal) RHSVal = 0;
}
if (!LHSVal && !RHSVal)
return 0;
Value *InLHS = FirstInst->getOperand(0);
Value *InRHS = FirstInst->getOperand(1);
PHINode *NewLHS = 0, *NewRHS = 0;
if (LHSVal == 0) {
NewLHS = PHINode::Create(LHSType, PN.getNumIncomingValues(),
FirstInst->getOperand(0)->getName() + ".pn");
NewLHS->addIncoming(InLHS, PN.getIncomingBlock(0));
InsertNewInstBefore(NewLHS, PN);
LHSVal = NewLHS;
}
if (RHSVal == 0) {
NewRHS = PHINode::Create(RHSType, PN.getNumIncomingValues(),
FirstInst->getOperand(1)->getName() + ".pn");
NewRHS->addIncoming(InRHS, PN.getIncomingBlock(0));
InsertNewInstBefore(NewRHS, PN);
RHSVal = NewRHS;
}
if (NewLHS || NewRHS) {
for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
Instruction *InInst = cast<Instruction>(PN.getIncomingValue(i));
if (NewLHS) {
Value *NewInLHS = InInst->getOperand(0);
NewLHS->addIncoming(NewInLHS, PN.getIncomingBlock(i));
}
if (NewRHS) {
Value *NewInRHS = InInst->getOperand(1);
NewRHS->addIncoming(NewInRHS, PN.getIncomingBlock(i));
}
}
}
if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst)) {
CmpInst *NewCI = CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
LHSVal, RHSVal);
NewCI->setDebugLoc(FirstInst->getDebugLoc());
return NewCI;
}
BinaryOperator *BinOp = cast<BinaryOperator>(FirstInst);
BinaryOperator *NewBinOp =
BinaryOperator::Create(BinOp->getOpcode(), LHSVal, RHSVal);
if (isNUW) NewBinOp->setHasNoUnsignedWrap();
if (isNSW) NewBinOp->setHasNoSignedWrap();
if (isExact) NewBinOp->setIsExact();
NewBinOp->setDebugLoc(FirstInst->getDebugLoc());
return NewBinOp;
}
Instruction *InstCombiner::FoldPHIArgGEPIntoPHI(PHINode &PN) {
GetElementPtrInst *FirstInst =cast<GetElementPtrInst>(PN.getIncomingValue(0));
SmallVector<Value*, 16> FixedOperands(FirstInst->op_begin(),
FirstInst->op_end());
bool AllBasePointersAreAllocas = true;
bool NeededPhi = false;
bool AllInBounds = true;
for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
GetElementPtrInst *GEP= dyn_cast<GetElementPtrInst>(PN.getIncomingValue(i));
if (!GEP || !GEP->hasOneUse() || GEP->getType() != FirstInst->getType() ||
GEP->getNumOperands() != FirstInst->getNumOperands())
return 0;
AllInBounds &= GEP->isInBounds();
if (AllBasePointersAreAllocas &&
(!isa<AllocaInst>(GEP->getOperand(0)) ||
!GEP->hasAllConstantIndices()))
AllBasePointersAreAllocas = false;
for (unsigned op = 0, e = FirstInst->getNumOperands(); op != e; ++op) {
if (FirstInst->getOperand(op) == GEP->getOperand(op))
continue;
if (isa<ConstantInt>(FirstInst->getOperand(op)) ||
isa<ConstantInt>(GEP->getOperand(op)))
return 0;
if (FirstInst->getOperand(op)->getType() !=GEP->getOperand(op)->getType())
return 0;
if (NeededPhi)
return 0;
FixedOperands[op] = 0; NeededPhi = true;
}
}
if (AllBasePointersAreAllocas)
return 0;
SmallVector<PHINode*, 16> OperandPhis(FixedOperands.size());
bool HasAnyPHIs = false;
for (unsigned i = 0, e = FixedOperands.size(); i != e; ++i) {
if (FixedOperands[i]) continue; Value *FirstOp = FirstInst->getOperand(i);
PHINode *NewPN = PHINode::Create(FirstOp->getType(), e,
FirstOp->getName()+".pn");
InsertNewInstBefore(NewPN, PN);
NewPN->addIncoming(FirstOp, PN.getIncomingBlock(0));
OperandPhis[i] = NewPN;
FixedOperands[i] = NewPN;
HasAnyPHIs = true;
}
if (HasAnyPHIs) {
for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
GetElementPtrInst *InGEP =cast<GetElementPtrInst>(PN.getIncomingValue(i));
BasicBlock *InBB = PN.getIncomingBlock(i);
for (unsigned op = 0, e = OperandPhis.size(); op != e; ++op)
if (PHINode *OpPhi = OperandPhis[op])
OpPhi->addIncoming(InGEP->getOperand(op), InBB);
}
}
Value *Base = FixedOperands[0];
GetElementPtrInst *NewGEP =
GetElementPtrInst::Create(Base, makeArrayRef(FixedOperands).slice(1));
if (AllInBounds) NewGEP->setIsInBounds();
NewGEP->setDebugLoc(FirstInst->getDebugLoc());
return NewGEP;
}
static bool isSafeAndProfitableToSinkLoad(LoadInst *L) {
BasicBlock::iterator BBI = L, E = L->getParent()->end();
for (++BBI; BBI != E; ++BBI)
if (BBI->mayWriteToMemory())
return false;
if (AllocaInst *AI = dyn_cast<AllocaInst>(L->getOperand(0))) {
bool isAddressTaken = false;
for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
UI != E; ++UI) {
User *U = *UI;
if (isa<LoadInst>(U)) continue;
if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
if (SI->getOperand(1) == AI) continue;
}
isAddressTaken = true;
break;
}
if (!isAddressTaken && AI->isStaticAlloca())
return false;
}
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(L->getOperand(0)))
if (AllocaInst *AI = dyn_cast<AllocaInst>(GEP->getOperand(0)))
if (AI->isStaticAlloca() && GEP->hasAllConstantIndices())
return false;
return true;
}
Instruction *InstCombiner::FoldPHIArgLoadIntoPHI(PHINode &PN) {
LoadInst *FirstLI = cast<LoadInst>(PN.getIncomingValue(0));
if (FirstLI->isAtomic())
return 0;
bool isVolatile = FirstLI->isVolatile();
unsigned LoadAlignment = FirstLI->getAlignment();
unsigned LoadAddrSpace = FirstLI->getPointerAddressSpace();
if (FirstLI->getParent() != PN.getIncomingBlock(0) ||
!isSafeAndProfitableToSinkLoad(FirstLI))
return 0;
if (isVolatile &&
FirstLI->getParent()->getTerminator()->getNumSuccessors() != 1)
return 0;
for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
LoadInst *LI = dyn_cast<LoadInst>(PN.getIncomingValue(i));
if (!LI || !LI->hasOneUse())
return 0;
if (LI->isVolatile() != isVolatile ||
LI->getParent() != PN.getIncomingBlock(i) ||
LI->getPointerAddressSpace() != LoadAddrSpace ||
!isSafeAndProfitableToSinkLoad(LI))
return 0;
if ((LoadAlignment != 0) != (LI->getAlignment() != 0))
return 0;
LoadAlignment = std::min(LoadAlignment, LI->getAlignment());
if (isVolatile &&
LI->getParent()->getTerminator()->getNumSuccessors() != 1)
return 0;
}
PHINode *NewPN = PHINode::Create(FirstLI->getOperand(0)->getType(),
PN.getNumIncomingValues(),
PN.getName()+".in");
Value *InVal = FirstLI->getOperand(0);
NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
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) {
PhiVal = InVal;
delete NewPN;
} else {
InsertNewInstBefore(NewPN, PN);
PhiVal = NewPN;
}
if (isVolatile)
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
cast<LoadInst>(PN.getIncomingValue(i))->setVolatile(false);
LoadInst *NewLI = new LoadInst(PhiVal, "", isVolatile, LoadAlignment);
NewLI->setDebugLoc(FirstLI->getDebugLoc());
return NewLI;
}
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);
Constant *ConstantOp = 0;
Type *CastSrcTy = 0;
bool isNUW = false, isNSW = false, isExact = false;
if (isa<CastInst>(FirstInst)) {
CastSrcTy = FirstInst->getOperand(0)->getType();
if (PN.getType()->isIntegerTy() && CastSrcTy->isIntegerTy()) {
if (!ShouldChangeType(PN.getType(), CastSrcTy))
return 0;
}
} else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) {
ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
if (ConstantOp == 0)
return FoldPHIArgBinOpIntoPHI(PN);
if (OverflowingBinaryOperator *BO =
dyn_cast<OverflowingBinaryOperator>(FirstInst)) {
isNUW = BO->hasNoUnsignedWrap();
isNSW = BO->hasNoSignedWrap();
} else if (PossiblyExactOperator *PEO =
dyn_cast<PossiblyExactOperator>(FirstInst))
isExact = PEO->isExact();
} else {
return 0; }
for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
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; } else if (I->getOperand(1) != ConstantOp) {
return 0;
}
if (isNUW)
isNUW = cast<OverflowingBinaryOperator>(I)->hasNoUnsignedWrap();
if (isNSW)
isNSW = cast<OverflowingBinaryOperator>(I)->hasNoSignedWrap();
if (isExact)
isExact = cast<PossiblyExactOperator>(I)->isExact();
}
PHINode *NewPN = PHINode::Create(FirstInst->getOperand(0)->getType(),
PN.getNumIncomingValues(),
PN.getName()+".in");
Value *InVal = FirstInst->getOperand(0);
NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
if (NewInVal != InVal)
InVal = 0;
NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
}
Value *PhiVal;
if (InVal) {
PhiVal = InVal;
delete NewPN;
} else {
InsertNewInstBefore(NewPN, PN);
PhiVal = NewPN;
}
if (CastInst *FirstCI = dyn_cast<CastInst>(FirstInst)) {
CastInst *NewCI = CastInst::Create(FirstCI->getOpcode(), PhiVal,
PN.getType());
NewCI->setDebugLoc(FirstInst->getDebugLoc());
return NewCI;
}
if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst)) {
BinOp = BinaryOperator::Create(BinOp->getOpcode(), PhiVal, ConstantOp);
if (isNUW) BinOp->setHasNoUnsignedWrap();
if (isNSW) BinOp->setHasNoSignedWrap();
if (isExact) BinOp->setIsExact();
BinOp->setDebugLoc(FirstInst->getDebugLoc());
return BinOp;
}
CmpInst *CIOp = cast<CmpInst>(FirstInst);
CmpInst *NewCI = CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
PhiVal, ConstantOp);
NewCI->setDebugLoc(FirstInst->getDebugLoc());
return NewCI;
}
static bool DeadPHICycle(PHINode *PN,
SmallPtrSet<PHINode*, 16> &PotentiallyDeadPHIs) {
if (PN->use_empty()) return true;
if (!PN->hasOneUse()) return false;
if (!PotentiallyDeadPHIs.insert(PN))
return true;
if (PotentiallyDeadPHIs.size() == 16)
return false;
if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
return DeadPHICycle(PU, PotentiallyDeadPHIs);
return false;
}
static bool PHIsEqualValue(PHINode *PN, Value *NonPhiInVal,
SmallPtrSet<PHINode*, 16> &ValueEqualPHIs) {
if (!ValueEqualPHIs.insert(PN))
return true;
if (ValueEqualPHIs.size() == 16)
return false;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
Value *Op = PN->getIncomingValue(i);
if (PHINode *OpPN = dyn_cast<PHINode>(Op)) {
if (!PHIsEqualValue(OpPN, NonPhiInVal, ValueEqualPHIs))
return false;
} else if (Op != NonPhiInVal)
return false;
}
return true;
}
namespace {
struct PHIUsageRecord {
unsigned PHIId; unsigned Shift; Instruction *Inst;
PHIUsageRecord(unsigned pn, unsigned Sh, Instruction *User)
: PHIId(pn), Shift(Sh), Inst(User) {}
bool operator<(const PHIUsageRecord &RHS) const {
if (PHIId < RHS.PHIId) return true;
if (PHIId > RHS.PHIId) return false;
if (Shift < RHS.Shift) return true;
if (Shift > RHS.Shift) return false;
return Inst->getType()->getPrimitiveSizeInBits() <
RHS.Inst->getType()->getPrimitiveSizeInBits();
}
};
struct LoweredPHIRecord {
PHINode *PN; unsigned Shift; unsigned Width;
LoweredPHIRecord(PHINode *pn, unsigned Sh, Type *Ty)
: PN(pn), Shift(Sh), Width(Ty->getPrimitiveSizeInBits()) {}
LoweredPHIRecord(PHINode *pn, unsigned Sh)
: PN(pn), Shift(Sh), Width(0) {}
};
}
namespace llvm {
template<>
struct DenseMapInfo<LoweredPHIRecord> {
static inline LoweredPHIRecord getEmptyKey() {
return LoweredPHIRecord(0, 0);
}
static inline LoweredPHIRecord getTombstoneKey() {
return LoweredPHIRecord(0, 1);
}
static unsigned getHashValue(const LoweredPHIRecord &Val) {
return DenseMapInfo<PHINode*>::getHashValue(Val.PN) ^ (Val.Shift>>3) ^
(Val.Width>>3);
}
static bool isEqual(const LoweredPHIRecord &LHS,
const LoweredPHIRecord &RHS) {
return LHS.PN == RHS.PN && LHS.Shift == RHS.Shift &&
LHS.Width == RHS.Width;
}
};
template <>
struct isPodLike<LoweredPHIRecord> { static const bool value = true; };
}
Instruction *InstCombiner::SliceUpIllegalIntegerPHI(PHINode &FirstPhi) {
SmallVector<PHIUsageRecord, 16> PHIUsers;
SmallVector<PHINode*, 8> PHIsToSlice;
SmallPtrSet<PHINode*, 8> PHIsInspected;
PHIsToSlice.push_back(&FirstPhi);
PHIsInspected.insert(&FirstPhi);
for (unsigned PHIId = 0; PHIId != PHIsToSlice.size(); ++PHIId) {
PHINode *PN = PHIsToSlice[PHIId];
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
InvokeInst *II = dyn_cast<InvokeInst>(PN->getIncomingValue(i));
if (II == 0) continue;
if (II->getParent() != PN->getIncomingBlock(i))
continue;
return 0;
}
for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end();
UI != E; ++UI) {
Instruction *User = cast<Instruction>(*UI);
if (PHINode *UserPN = dyn_cast<PHINode>(User)) {
if (PHIsInspected.insert(UserPN))
PHIsToSlice.push_back(UserPN);
continue;
}
if (isa<TruncInst>(User)) {
PHIUsers.push_back(PHIUsageRecord(PHIId, 0, User));
continue;
}
if (User->getOpcode() != Instruction::LShr ||
!User->hasOneUse() || !isa<TruncInst>(User->use_back()) ||
!isa<ConstantInt>(User->getOperand(1)))
return 0;
unsigned Shift = cast<ConstantInt>(User->getOperand(1))->getZExtValue();
PHIUsers.push_back(PHIUsageRecord(PHIId, Shift, User->use_back()));
}
}
if (PHIUsers.empty())
return ReplaceInstUsesWith(FirstPhi, UndefValue::get(FirstPhi.getType()));
array_pod_sort(PHIUsers.begin(), PHIUsers.end());
DEBUG(errs() << "SLICING UP PHI: " << FirstPhi << '\n';
for (unsigned i = 1, e = PHIsToSlice.size(); i != e; ++i)
errs() << "AND USER PHI #" << i << ": " << *PHIsToSlice[i] <<'\n';
);
DenseMap<BasicBlock*, Value*> PredValues;
DenseMap<LoweredPHIRecord, PHINode*> ExtractedVals;
for (unsigned UserI = 0, UserE = PHIUsers.size(); UserI != UserE; ++UserI) {
unsigned PHIId = PHIUsers[UserI].PHIId;
PHINode *PN = PHIsToSlice[PHIId];
unsigned Offset = PHIUsers[UserI].Shift;
Type *Ty = PHIUsers[UserI].Inst->getType();
PHINode *EltPHI;
if ((EltPHI = ExtractedVals[LoweredPHIRecord(PN, Offset, Ty)]) == 0) {
EltPHI = PHINode::Create(Ty, PN->getNumIncomingValues(),
PN->getName()+".off"+Twine(Offset), PN);
assert(EltPHI->getType() != PN->getType() &&
"Truncate didn't shrink phi?");
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
BasicBlock *Pred = PN->getIncomingBlock(i);
Value *&PredVal = PredValues[Pred];
if (PredVal) {
EltPHI->addIncoming(PredVal, Pred);
continue;
}
Value *InVal = PN->getIncomingValue(i);
if (InVal == PN) {
PredVal = EltPHI;
EltPHI->addIncoming(PredVal, Pred);
continue;
}
if (PHINode *InPHI = dyn_cast<PHINode>(PN)) {
if (Value *Res = ExtractedVals[LoweredPHIRecord(InPHI, Offset, Ty)]) {
PredVal = Res;
EltPHI->addIncoming(PredVal, Pred);
continue;
}
}
Builder->SetInsertPoint(Pred, Pred->getTerminator());
Value *Res = InVal;
if (Offset)
Res = Builder->CreateLShr(Res, ConstantInt::get(InVal->getType(),
Offset), "extract");
Res = Builder->CreateTrunc(Res, Ty, "extract.t");
PredVal = Res;
EltPHI->addIncoming(Res, Pred);
if (PHINode *OldInVal = dyn_cast<PHINode>(PN->getIncomingValue(i)))
if (PHIsInspected.count(OldInVal)) {
unsigned RefPHIId = std::find(PHIsToSlice.begin(),PHIsToSlice.end(),
OldInVal)-PHIsToSlice.begin();
PHIUsers.push_back(PHIUsageRecord(RefPHIId, Offset,
cast<Instruction>(Res)));
++UserE;
}
}
PredValues.clear();
DEBUG(errs() << " Made element PHI for offset " << Offset << ": "
<< *EltPHI << '\n');
ExtractedVals[LoweredPHIRecord(PN, Offset, Ty)] = EltPHI;
}
ReplaceInstUsesWith(*PHIUsers[UserI].Inst, EltPHI);
}
Value *Undef = UndefValue::get(FirstPhi.getType());
for (unsigned i = 1, e = PHIsToSlice.size(); i != e; ++i)
ReplaceInstUsesWith(*PHIsToSlice[i], Undef);
return ReplaceInstUsesWith(FirstPhi, Undef);
}
Instruction *InstCombiner::visitPHINode(PHINode &PN) {
if (Value *V = SimplifyInstruction(&PN, TD))
return ReplaceInstUsesWith(PN, V);
if (isa<Instruction>(PN.getIncomingValue(0)) &&
isa<Instruction>(PN.getIncomingValue(1)) &&
cast<Instruction>(PN.getIncomingValue(0))->getOpcode() ==
cast<Instruction>(PN.getIncomingValue(1))->getOpcode() &&
PN.getIncomingValue(0)->hasOneUse())
if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
return Result;
if (PN.hasOneUse()) {
Instruction *PHIUser = cast<Instruction>(PN.use_back());
if (PHINode *PU = dyn_cast<PHINode>(PHIUser)) {
SmallPtrSet<PHINode*, 16> PotentiallyDeadPHIs;
PotentiallyDeadPHIs.insert(&PN);
if (DeadPHICycle(PU, PotentiallyDeadPHIs))
return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
}
if (PHIUser->hasOneUse() &&
(isa<BinaryOperator>(PHIUser) || isa<GetElementPtrInst>(PHIUser)) &&
PHIUser->use_back() == &PN) {
return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
}
}
{
unsigned InValNo = 0, NumIncomingVals = PN.getNumIncomingValues();
while (InValNo != NumIncomingVals &&
isa<PHINode>(PN.getIncomingValue(InValNo)))
++InValNo;
if (InValNo != NumIncomingVals) {
Value *NonPhiInVal = PN.getIncomingValue(InValNo);
for (++InValNo; InValNo != NumIncomingVals; ++InValNo) {
Value *OpVal = PN.getIncomingValue(InValNo);
if (OpVal != NonPhiInVal && !isa<PHINode>(OpVal))
break;
}
if (InValNo == NumIncomingVals) {
SmallPtrSet<PHINode*, 16> ValueEqualPHIs;
if (PHIsEqualValue(&PN, NonPhiInVal, ValueEqualPHIs))
return ReplaceInstUsesWith(PN, NonPhiInVal);
}
}
}
PHINode *FirstPN = cast<PHINode>(PN.getParent()->begin());
if (&PN != FirstPN)
for (unsigned i = 0, e = FirstPN->getNumIncomingValues(); i != e; ++i) {
BasicBlock *BBA = PN.getIncomingBlock(i);
BasicBlock *BBB = FirstPN->getIncomingBlock(i);
if (BBA != BBB) {
Value *VA = PN.getIncomingValue(i);
unsigned j = PN.getBasicBlockIndex(BBB);
Value *VB = PN.getIncomingValue(j);
PN.setIncomingBlock(i, BBB);
PN.setIncomingValue(i, VB);
PN.setIncomingBlock(j, BBA);
PN.setIncomingValue(j, VA);
}
}
if (PN.getType()->isIntegerTy() && TD &&
!TD->isLegalInteger(PN.getType()->getPrimitiveSizeInBits()))
if (Instruction *Res = SliceUpIllegalIntegerPHI(PN))
return Res;
return 0;
}