const SCEV *
ScalarEvolution::getConstant(const Type *Ty, uint64_t V, bool isSigned) {
- return getConstant(
- ConstantInt::get(cast<IntegerType>(Ty), V, isSigned));
+ const IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty));
+ return getConstant(ConstantInt::get(ITy, V, isSigned));
}
const Type *SCEVConstant::getType() const { return V->getType(); }
}
void SCEVCommutativeExpr::print(raw_ostream &OS) const {
- assert(NumOperands > 1 && "This plus expr shouldn't exist!");
const char *OpStr = getOperationStr();
- OS << "(" << *Operands[0];
- for (unsigned i = 1, e = NumOperands; i != e; ++i)
- OS << OpStr << *Operands[i];
+ OS << "(";
+ for (op_iterator I = op_begin(), E = op_end(); I != E; ++I) {
+ OS << **I;
+ if (next(I) != E)
+ OS << OpStr;
+ }
OS << ")";
}
}
} else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
// Pull a buried constant out to the outside.
- if (Scale != 1 || AccumulatedConstant != 0 || C->isZero())
+ if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero())
Interesting = true;
AccumulatedConstant += Scale * C->getValue()->getValue();
} else {
}
// If we are left with a constant zero being added, strip it off.
- if (cast<SCEVConstant>(Ops[0])->getValue()->isZero()) {
+ if (LHSC->getValue()->isZero()) {
Ops.erase(Ops.begin());
--Idx;
}
- }
- if (Ops.size() == 1) return Ops[0];
+ if (Ops.size() == 1) return Ops[0];
+ }
// Okay, check to see if the same value occurs in the operand list twice. If
// so, merge them together into an multiply expression. Since we sorted the
}
LargeOps.push_back(T->getOperand());
} else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
- // This could be either sign or zero extension, but sign extension
- // is much more likely to be foldable here.
- LargeOps.push_back(getSignExtendExpr(C, SrcType));
+ LargeOps.push_back(getAnyExtendExpr(C, SrcType));
} else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) {
SmallVector<const SCEV *, 8> LargeMulOps;
for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) {
LargeMulOps.push_back(T->getOperand());
} else if (const SCEVConstant *C =
dyn_cast<SCEVConstant>(M->getOperand(j))) {
- // This could be either sign or zero extension, but sign extension
- // is much more likely to be foldable here.
- LargeMulOps.push_back(getSignExtendExpr(C, SrcType));
+ LargeMulOps.push_back(getAnyExtendExpr(C, SrcType));
} else {
Ok = false;
break;
// they are loop invariant w.r.t. the recurrence.
SmallVector<const SCEV *, 8> LIOps;
const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
+ const Loop *AddRecLoop = AddRec->getLoop();
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- if (Ops[i]->isLoopInvariant(AddRec->getLoop())) {
+ if (Ops[i]->isLoopInvariant(AddRecLoop)) {
LIOps.push_back(Ops[i]);
Ops.erase(Ops.begin()+i);
--i; --e;
// It's tempting to propagate NUW/NSW flags here, but nuw/nsw addition
// is not associative so this isn't necessarily safe.
- const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRec->getLoop());
+ const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop);
// If all of the other operands were loop invariant, we are done.
if (Ops.size() == 1) return NewRec;
OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);++OtherIdx)
if (OtherIdx != Idx) {
const SCEVAddRecExpr *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]);
- if (AddRec->getLoop() == OtherAddRec->getLoop()) {
+ if (AddRecLoop == OtherAddRec->getLoop()) {
// Other + {A,+,B} + {C,+,D} --> Other + {A+C,+,B+D}
SmallVector<const SCEV *, 4> NewOps(AddRec->op_begin(),
AddRec->op_end());
}
NewOps[i] = getAddExpr(NewOps[i], OtherAddRec->getOperand(i));
}
- const SCEV *NewAddRec = getAddRecExpr(NewOps, AddRec->getLoop());
+ const SCEV *NewAddRec = getAddRecExpr(NewOps, AddRecLoop);
if (Ops.size() == 2) return NewAddRec;
return getAddExpr(NewOps);
}
}
+
+ if (Ops.size() == 1)
+ return Ops[0];
}
// Skip over the add expression until we get to a multiply.
while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
++Idx;
- if (Ops.size() == 1)
- return Ops[0];
-
// If there are mul operands inline them all into this expression.
if (Idx < Ops.size()) {
bool DeletedMul = false;
if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
if (RHSC->getValue()->equalsInt(1))
return LHS; // X udiv 1 --> x
- if (RHSC->isZero())
- return getIntegerSCEV(0, LHS->getType()); // value is undefined
-
- // Determine if the division can be folded into the operands of
- // its operands.
- // TODO: Generalize this to non-constants by using known-bits information.
- const Type *Ty = LHS->getType();
- unsigned LZ = RHSC->getValue()->getValue().countLeadingZeros();
- unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ;
- // For non-power-of-two values, effectively round the value up to the
- // nearest power of two.
- if (!RHSC->getValue()->getValue().isPowerOf2())
- ++MaxShiftAmt;
- const IntegerType *ExtTy =
- IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt);
- // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded.
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
- if (const SCEVConstant *Step =
- dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this)))
- if (!Step->getValue()->getValue()
- .urem(RHSC->getValue()->getValue()) &&
- getZeroExtendExpr(AR, ExtTy) ==
- getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
- getZeroExtendExpr(Step, ExtTy),
- AR->getLoop())) {
- SmallVector<const SCEV *, 4> Operands;
- for (unsigned i = 0, e = AR->getNumOperands(); i != e; ++i)
- Operands.push_back(getUDivExpr(AR->getOperand(i), RHS));
- return getAddRecExpr(Operands, AR->getLoop());
- }
- // (A*B)/C --> A*(B/C) if safe and B/C can be folded.
- if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) {
- SmallVector<const SCEV *, 4> Operands;
- for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i)
- Operands.push_back(getZeroExtendExpr(M->getOperand(i), ExtTy));
- if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands))
- // Find an operand that's safely divisible.
- for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
- const SCEV *Op = M->getOperand(i);
- const SCEV *Div = getUDivExpr(Op, RHSC);
- if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) {
- Operands = SmallVector<const SCEV *, 4>(M->op_begin(), M->op_end());
- Operands[i] = Div;
- return getMulExpr(Operands);
+ // If the denominator is zero, the result of the udiv is undefined. Don't
+ // try to analyze it, because the resolution chosen here may differ from
+ // the resolution chosen in other parts of the compiler.
+ if (!RHSC->getValue()->isZero()) {
+ // Determine if the division can be folded into the operands of
+ // its operands.
+ // TODO: Generalize this to non-constants by using known-bits information.
+ const Type *Ty = LHS->getType();
+ unsigned LZ = RHSC->getValue()->getValue().countLeadingZeros();
+ unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ;
+ // For non-power-of-two values, effectively round the value up to the
+ // nearest power of two.
+ if (!RHSC->getValue()->getValue().isPowerOf2())
+ ++MaxShiftAmt;
+ const IntegerType *ExtTy =
+ IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt);
+ // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded.
+ if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
+ if (const SCEVConstant *Step =
+ dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this)))
+ if (!Step->getValue()->getValue()
+ .urem(RHSC->getValue()->getValue()) &&
+ getZeroExtendExpr(AR, ExtTy) ==
+ getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
+ getZeroExtendExpr(Step, ExtTy),
+ AR->getLoop())) {
+ SmallVector<const SCEV *, 4> Operands;
+ for (unsigned i = 0, e = AR->getNumOperands(); i != e; ++i)
+ Operands.push_back(getUDivExpr(AR->getOperand(i), RHS));
+ return getAddRecExpr(Operands, AR->getLoop());
}
+ // (A*B)/C --> A*(B/C) if safe and B/C can be folded.
+ if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) {
+ SmallVector<const SCEV *, 4> Operands;
+ for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i)
+ Operands.push_back(getZeroExtendExpr(M->getOperand(i), ExtTy));
+ if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands))
+ // Find an operand that's safely divisible.
+ for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
+ const SCEV *Op = M->getOperand(i);
+ const SCEV *Div = getUDivExpr(Op, RHSC);
+ if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) {
+ Operands = SmallVector<const SCEV *, 4>(M->op_begin(),
+ M->op_end());
+ Operands[i] = Div;
+ return getMulExpr(Operands);
+ }
+ }
+ }
+ // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded.
+ if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(LHS)) {
+ SmallVector<const SCEV *, 4> Operands;
+ for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i)
+ Operands.push_back(getZeroExtendExpr(A->getOperand(i), ExtTy));
+ if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) {
+ Operands.clear();
+ for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) {
+ const SCEV *Op = getUDivExpr(A->getOperand(i), RHS);
+ if (isa<SCEVUDivExpr>(Op) ||
+ getMulExpr(Op, RHS) != A->getOperand(i))
+ break;
+ Operands.push_back(Op);
+ }
+ if (Operands.size() == A->getNumOperands())
+ return getAddExpr(Operands);
}
- }
- // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded.
- if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(LHS)) {
- SmallVector<const SCEV *, 4> Operands;
- for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i)
- Operands.push_back(getZeroExtendExpr(A->getOperand(i), ExtTy));
- if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) {
- Operands.clear();
- for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) {
- const SCEV *Op = getUDivExpr(A->getOperand(i), RHS);
- if (isa<SCEVUDivExpr>(Op) || getMulExpr(Op, RHS) != A->getOperand(i))
- break;
- Operands.push_back(Op);
- }
- if (Operands.size() == A->getNumOperands())
- return getAddExpr(Operands);
}
- }
- // Fold if both operands are constant.
- if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
- Constant *LHSCV = LHSC->getValue();
- Constant *RHSCV = RHSC->getValue();
- return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV,
- RHSCV)));
+ // Fold if both operands are constant.
+ if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
+ Constant *LHSCV = LHSC->getValue();
+ Constant *RHSCV = RHSC->getValue();
+ return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV,
+ RHSCV)));
+ }
}
}
// maximum-int.
return Ops[0];
}
- }
- if (Ops.size() == 1) return Ops[0];
+ if (Ops.size() == 1) return Ops[0];
+ }
// Find the first SMax
while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scSMaxExpr)
// so, delete one. Since we sorted the list, these values are required to
// be adjacent.
for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
- if (Ops[i] == Ops[i+1]) { // X smax Y smax Y --> X smax Y
+ // X smax Y smax Y --> X smax Y
+ // X smax Y --> X, if X is always greater than Y
+ if (Ops[i] == Ops[i+1] ||
+ isKnownPredicate(ICmpInst::ICMP_SGE, Ops[i], Ops[i+1])) {
+ Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
+ --i; --e;
+ } else if (isKnownPredicate(ICmpInst::ICMP_SLE, Ops[i], Ops[i+1])) {
Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
--i; --e;
}
// maximum-int.
return Ops[0];
}
- }
- if (Ops.size() == 1) return Ops[0];
+ if (Ops.size() == 1) return Ops[0];
+ }
// Find the first UMax
while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scUMaxExpr)
// so, delete one. Since we sorted the list, these values are required to
// be adjacent.
for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
- if (Ops[i] == Ops[i+1]) { // X umax Y umax Y --> X umax Y
+ // X umax Y umax Y --> X umax Y
+ // X umax Y --> X, if X is always greater than Y
+ if (Ops[i] == Ops[i+1] ||
+ isKnownPredicate(ICmpInst::ICMP_UGE, Ops[i], Ops[i+1])) {
+ Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
+ --i; --e;
+ } else if (isKnownPredicate(ICmpInst::ICMP_ULE, Ops[i], Ops[i+1])) {
Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
--i; --e;
}
}
const SCEV *ScalarEvolution::getSizeOfExpr(const Type *AllocTy) {
+ // If we have TargetData, we can bypass creating a target-independent
+ // constant expression and then folding it back into a ConstantInt.
+ // This is just a compile-time optimization.
+ if (TD)
+ return getConstant(TD->getIntPtrType(getContext()),
+ TD->getTypeAllocSize(AllocTy));
+
Constant *C = ConstantExpr::getSizeOf(AllocTy);
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
C = ConstantFoldConstantExpression(CE, TD);
const SCEV *ScalarEvolution::getOffsetOfExpr(const StructType *STy,
unsigned FieldNo) {
+ // If we have TargetData, we can bypass creating a target-independent
+ // constant expression and then folding it back into a ConstantInt.
+ // This is just a compile-time optimization.
+ if (TD)
+ return getConstant(TD->getIntPtrType(getContext()),
+ TD->getStructLayout(STy)->getElementOffset(FieldNo));
+
Constant *C = ConstantExpr::getOffsetOf(STy, FieldNo);
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
C = ConstantFoldConstantExpression(CE, TD);
/// a loop header, making it a potential recurrence, or it doesn't.
///
const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
- if (PN->getNumIncomingValues() == 2) // The loops have been canonicalized.
- if (const Loop *L = LI->getLoopFor(PN->getParent()))
- if (L->getHeader() == PN->getParent()) {
- // If it lives in the loop header, it has two incoming values, one
- // from outside the loop, and one from inside.
- unsigned IncomingEdge = L->contains(PN->getIncomingBlock(0));
- unsigned BackEdge = IncomingEdge^1;
-
+ if (const Loop *L = LI->getLoopFor(PN->getParent()))
+ if (L->getHeader() == PN->getParent()) {
+ // The loop may have multiple entrances or multiple exits; we can analyze
+ // this phi as an addrec if it has a unique entry value and a unique
+ // backedge value.
+ Value *BEValueV = 0, *StartValueV = 0;
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ Value *V = PN->getIncomingValue(i);
+ if (L->contains(PN->getIncomingBlock(i))) {
+ if (!BEValueV) {
+ BEValueV = V;
+ } else if (BEValueV != V) {
+ BEValueV = 0;
+ break;
+ }
+ } else if (!StartValueV) {
+ StartValueV = V;
+ } else if (StartValueV != V) {
+ StartValueV = 0;
+ break;
+ }
+ }
+ if (BEValueV && StartValueV) {
// While we are analyzing this PHI node, handle its value symbolically.
const SCEV *SymbolicName = getUnknown(PN);
assert(Scalars.find(PN) == Scalars.end() &&
// Using this symbolic name for the PHI, analyze the value coming around
// the back-edge.
- Value *BEValueV = PN->getIncomingValue(BackEdge);
const SCEV *BEValue = getSCEV(BEValueV);
// NOTE: If BEValue is loop invariant, we know that the PHI node just
HasNSW = true;
}
- const SCEV *StartVal =
- getSCEV(PN->getIncomingValue(IncomingEdge));
+ const SCEV *StartVal = getSCEV(StartValueV);
const SCEV *PHISCEV =
getAddRecExpr(StartVal, Accum, L, HasNUW, HasNSW);
// Because the other in-value of i (0) fits the evolution of BEValue
// i really is an addrec evolution.
if (AddRec->getLoop() == L && AddRec->isAffine()) {
- const SCEV *StartVal = getSCEV(PN->getIncomingValue(IncomingEdge));
+ const SCEV *StartVal = getSCEV(StartValueV);
// If StartVal = j.start - j.stride, we can use StartVal as the
// initial step of the addrec evolution.
}
}
}
-
- return SymbolicName;
}
+ }
// If the PHI has a single incoming value, follow that value, unless the
// PHI's incoming blocks are in a different loop, in which case doing so
// initial value.
if (AddRec->hasNoUnsignedWrap())
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(AddRec->getStart()))
- if (!C->isZero())
+ if (!C->getValue()->isZero())
ConservativeResult =
ConstantRange(C->getValue()->getValue(), APInt(BitWidth, 0));
// Turn shift left of a constant amount into a multiply.
if (ConstantInt *SA = dyn_cast<ConstantInt>(U->getOperand(1))) {
uint32_t BitWidth = cast<IntegerType>(U->getType())->getBitWidth();
+
+ // If the shift count is not less than the bitwidth, the result of
+ // the shift is undefined. Don't try to analyze it, because the
+ // resolution chosen here may differ from the resolution chosen in
+ // other parts of the compiler.
+ if (SA->getValue().uge(BitWidth))
+ break;
+
Constant *X = ConstantInt::get(getContext(),
- APInt(BitWidth, 1).shl(SA->getLimitedValue(BitWidth)));
+ APInt(BitWidth, 1).shl(SA->getZExtValue()));
return getMulExpr(getSCEV(U->getOperand(0)), getSCEV(X));
}
break;
// Turn logical shift right of a constant into a unsigned divide.
if (ConstantInt *SA = dyn_cast<ConstantInt>(U->getOperand(1))) {
uint32_t BitWidth = cast<IntegerType>(U->getType())->getBitWidth();
+
+ // If the shift count is not less than the bitwidth, the result of
+ // the shift is undefined. Don't try to analyze it, because the
+ // resolution chosen here may differ from the resolution chosen in
+ // other parts of the compiler.
+ if (SA->getValue().uge(BitWidth))
+ break;
+
Constant *X = ConstantInt::get(getContext(),
- APInt(BitWidth, 1).shl(SA->getLimitedValue(BitWidth)));
+ APInt(BitWidth, 1).shl(SA->getZExtValue()));
return getUDivExpr(getSCEV(U->getOperand(0)), getSCEV(X));
}
break;
case Instruction::AShr:
// For a two-shift sext-inreg, use sext(trunc(x)) as the SCEV expression.
if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1)))
- if (Instruction *L = dyn_cast<Instruction>(U->getOperand(0)))
+ if (Operator *L = dyn_cast<Operator>(U->getOperand(0)))
if (L->getOpcode() == Instruction::Shl &&
L->getOperand(1) == U->getOperand(1)) {
- unsigned BitWidth = getTypeSizeInBits(U->getType());
+ uint64_t BitWidth = getTypeSizeInBits(U->getType());
+
+ // If the shift count is not less than the bitwidth, the result of
+ // the shift is undefined. Don't try to analyze it, because the
+ // resolution chosen here may differ from the resolution chosen in
+ // other parts of the compiler.
+ if (CI->getValue().uge(BitWidth))
+ break;
+
uint64_t Amt = BitWidth - CI->getZExtValue();
if (Amt == BitWidth)
return getSCEV(L->getOperand(0)); // shift by zero --> noop
- if (Amt > BitWidth)
- return getIntegerSCEV(0, U->getType()); // value is undefined
return
getSignExtendExpr(getTruncateExpr(getSCEV(L->getOperand(0)),
- IntegerType::get(getContext(), Amt)),
- U->getType());
+ IntegerType::get(getContext(),
+ Amt)),
+ U->getType());
}
break;
/// getLoopPredecessor - If the given loop's header has exactly one unique
/// predecessor outside the loop, return it. Otherwise return null.
+/// This is less strict that the loop "preheader" concept, which requires
+/// the predecessor to have only one single successor.
///
BasicBlock *ScalarEvolution::getLoopPredecessor(const Loop *L) {
BasicBlock *Header = L->getHeader();
/// successor from which BB is reachable, or null if no such block is
/// found.
///
-BasicBlock *
+std::pair<BasicBlock *, BasicBlock *>
ScalarEvolution::getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB) {
// If the block has a unique predecessor, then there is no path from the
// predecessor to the block that does not go through the direct edge
// from the predecessor to the block.
if (BasicBlock *Pred = BB->getSinglePredecessor())
- return Pred;
+ return std::make_pair(Pred, BB);
// A loop's header is defined to be a block that dominates the loop.
// If the header has a unique predecessor outside the loop, it must be
// a block that has exactly one successor that can reach the loop.
if (Loop *L = LI->getLoopFor(BB))
- return getLoopPredecessor(L);
+ return std::make_pair(getLoopPredecessor(L), L->getHeader());
- return 0;
+ return std::pair<BasicBlock *, BasicBlock *>();
}
/// HasSameValue - SCEV structural equivalence is usually sufficient for
// (interprocedural conditions notwithstanding).
if (!L) return false;
- BasicBlock *Predecessor = getLoopPredecessor(L);
- BasicBlock *PredecessorDest = L->getHeader();
-
// Starting at the loop predecessor, climb up the predecessor chain, as long
// as there are predecessors that can be found that have unique successors
// leading to the original header.
- for (; Predecessor;
- PredecessorDest = Predecessor,
- Predecessor = getPredecessorWithUniqueSuccessorForBB(Predecessor)) {
+ for (std::pair<BasicBlock *, BasicBlock *>
+ Pair(getLoopPredecessor(L), L->getHeader());
+ Pair.first;
+ Pair = getPredecessorWithUniqueSuccessorForBB(Pair.first)) {
BranchInst *LoopEntryPredicate =
- dyn_cast<BranchInst>(Predecessor->getTerminator());
+ dyn_cast<BranchInst>(Pair.first->getTerminator());
if (!LoopEntryPredicate ||
LoopEntryPredicate->isUnconditional())
continue;
if (isImpliedCond(LoopEntryPredicate->getCondition(), Pred, LHS, RHS,
- LoopEntryPredicate->getSuccessor(0) != PredecessorDest))
+ LoopEntryPredicate->getSuccessor(0) != Pair.second))
return true;
}
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