STATISTIC(NumElimExt , "Number of IV sign/zero extends eliminated");
STATISTIC(NumElimIV , "Number of congruent IVs eliminated");
-namespace llvm {
- cl::opt<bool> EnableIVRewrite(
- "enable-iv-rewrite", cl::Hidden,
- cl::desc("Enable canonical induction variable rewriting"));
-
- // Trip count verification can be enabled by default under NDEBUG if we
- // implement a strong expression equivalence checker in SCEV. Until then, we
- // use the verify-indvars flag, which may assert in some cases.
- cl::opt<bool> VerifyIndvars(
- "verify-indvars", cl::Hidden,
- cl::desc("Verify the ScalarEvolution result after running indvars"));
-}
+static cl::opt<bool> EnableIVRewrite(
+ "enable-iv-rewrite", cl::Hidden,
+ cl::desc("Enable canonical induction variable rewriting"));
+
+// Trip count verification can be enabled by default under NDEBUG if we
+// implement a strong expression equivalence checker in SCEV. Until then, we
+// use the verify-indvars flag, which may assert in some cases.
+static cl::opt<bool> VerifyIndvars(
+ "verify-indvars", cl::Hidden,
+ cl::desc("Verify the ScalarEvolution result after running indvars"));
namespace {
class IndVarSimplify : public LoopPass {
void SimplifyAndExtend(Loop *L, SCEVExpander &Rewriter, LPPassManager &LPM);
- void SimplifyCongruentIVs(Loop *L);
-
void RewriteLoopExitValues(Loop *L, SCEVExpander &Rewriter);
void RewriteIVExpressions(Loop *L, SCEVExpander &Rewriter);
// base of a recurrence. This handles the case in which SCEV expansion
// converts a pointer type recurrence into a nonrecurrent pointer base
// indexed by an integer recurrence.
+
+ // If the GEP base pointer is a vector of pointers, abort.
+ if (!FromPtr->getType()->isPointerTy() || !ToPtr->getType()->isPointerTy())
+ return false;
+
const SCEV *FromBase = SE->getPointerBase(SE->getSCEV(FromPtr));
const SCEV *ToBase = SE->getPointerBase(SE->getSCEV(ToPtr));
if (FromBase == ToBase)
// extend operations. This information is recorded by CollectExtend and
// provides the input to WidenIV.
struct WideIVInfo {
+ PHINode *NarrowIV;
Type *WidestNativeType; // Widest integer type created [sz]ext
bool IsSigned; // Was an sext user seen before a zext?
- WideIVInfo() : WidestNativeType(0), IsSigned(false) {}
+ WideIVInfo() : NarrowIV(0), WidestNativeType(0), IsSigned(false) {}
};
class WideIVVisitor : public IVVisitor {
public:
WideIVInfo WI;
- WideIVVisitor(ScalarEvolution *SCEV, const TargetData *TData) :
- SE(SCEV), TD(TData) {}
+ WideIVVisitor(PHINode *NarrowIV, ScalarEvolution *SCEV,
+ const TargetData *TData) :
+ SE(SCEV), TD(TData) { WI.NarrowIV = NarrowIV; }
// Implement the interface used by simplifyUsersOfIV.
virtual void visitCast(CastInst *Cast);
SmallVector<NarrowIVDefUse, 8> NarrowIVUsers;
public:
- WidenIV(PHINode *PN, const WideIVInfo &WI, LoopInfo *LInfo,
+ WidenIV(const WideIVInfo &WI, LoopInfo *LInfo,
ScalarEvolution *SEv, DominatorTree *DTree,
SmallVectorImpl<WeakVH> &DI) :
- OrigPhi(PN),
+ OrigPhi(WI.NarrowIV),
WideType(WI.WidestNativeType),
IsSigned(WI.IsSigned),
LI(LInfo),
const SCEVAddRecExpr* GetExtendedOperandRecurrence(NarrowIVDefUse DU);
- Instruction *WidenIVUse(NarrowIVDefUse DU);
+ Instruction *WidenIVUse(NarrowIVDefUse DU, SCEVExpander &Rewriter);
void pushNarrowIVUsers(Instruction *NarrowDef, Instruction *WideDef);
};
}
return WideBO;
}
- llvm_unreachable(0);
-}
-
-/// HoistStep - Attempt to hoist an IV increment above a potential use.
-///
-/// To successfully hoist, two criteria must be met:
-/// - IncV operands dominate InsertPos and
-/// - InsertPos dominates IncV
-///
-/// Meeting the second condition means that we don't need to check all of IncV's
-/// existing uses (it's moving up in the domtree).
-///
-/// This does not yet recursively hoist the operands, although that would
-/// not be difficult.
-static bool HoistStep(Instruction *IncV, Instruction *InsertPos,
- const DominatorTree *DT)
-{
- if (DT->dominates(IncV, InsertPos))
- return true;
-
- if (!DT->dominates(InsertPos->getParent(), IncV->getParent()))
- return false;
-
- if (IncV->mayHaveSideEffects())
- return false;
-
- // Attempt to hoist IncV
- for (User::op_iterator OI = IncV->op_begin(), OE = IncV->op_end();
- OI != OE; ++OI) {
- Instruction *OInst = dyn_cast<Instruction>(OI);
- if (OInst && !DT->dominates(OInst, InsertPos))
- return false;
- }
- IncV->moveBefore(InsertPos);
- return true;
}
/// No-wrap operations can transfer sign extension of their result to their
else
return 0;
+ // When creating this AddExpr, don't apply the current operations NSW or NUW
+ // flags. This instruction may be guarded by control flow that the no-wrap
+ // behavior depends on. Non-control-equivalent instructions can be mapped to
+ // the same SCEV expression, and it would be incorrect to transfer NSW/NUW
+ // semantics to those operations.
const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(
- SE->getAddExpr(SE->getSCEV(DU.WideDef), ExtendOperExpr,
- IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW));
+ SE->getAddExpr(SE->getSCEV(DU.WideDef), ExtendOperExpr));
if (!AddRec || AddRec->getLoop() != L)
return 0;
/// WidenIVUse - Determine whether an individual user of the narrow IV can be
/// widened. If so, return the wide clone of the user.
-Instruction *WidenIV::WidenIVUse(NarrowIVDefUse DU) {
+Instruction *WidenIV::WidenIVUse(NarrowIVDefUse DU, SCEVExpander &Rewriter) {
// Stop traversing the def-use chain at inner-loop phis or post-loop phis.
if (isa<PHINode>(DU.NarrowUse) &&
// Reuse the IV increment that SCEVExpander created as long as it dominates
// NarrowUse.
Instruction *WideUse = 0;
- if (WideAddRec == WideIncExpr && HoistStep(WideInc, DU.NarrowUse, DT)) {
+ if (WideAddRec == WideIncExpr
+ && Rewriter.hoistIVInc(WideInc, DU.NarrowUse))
WideUse = WideInc;
- }
else {
WideUse = CloneIVUser(DU);
if (!WideUse)
// Process a def-use edge. This may replace the use, so don't hold a
// use_iterator across it.
- Instruction *WideUse = WidenIVUse(DU);
+ Instruction *WideUse = WidenIVUse(DU, Rewriter);
// Follow all def-use edges from the previous narrow use.
if (WideUse)
void IndVarSimplify::SimplifyAndExtend(Loop *L,
SCEVExpander &Rewriter,
LPPassManager &LPM) {
- std::map<PHINode *, WideIVInfo> WideIVMap;
+ SmallVector<WideIVInfo, 8> WideIVs;
SmallVector<PHINode*, 8> LoopPhis;
for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I) {
PHINode *CurrIV = LoopPhis.pop_back_val();
// Information about sign/zero extensions of CurrIV.
- WideIVVisitor WIV(SE, TD);
+ WideIVVisitor WIV(CurrIV, SE, TD);
Changed |= simplifyUsersOfIV(CurrIV, SE, &LPM, DeadInsts, &WIV);
if (WIV.WI.WidestNativeType) {
- WideIVMap[CurrIV] = WIV.WI;
+ WideIVs.push_back(WIV.WI);
}
} while(!LoopPhis.empty());
- for (std::map<PHINode *, WideIVInfo>::const_iterator I = WideIVMap.begin(),
- E = WideIVMap.end(); I != E; ++I) {
- WidenIV Widener(I->first, I->second, LI, SE, DT, DeadInsts);
+ for (; !WideIVs.empty(); WideIVs.pop_back()) {
+ WidenIV Widener(WideIVs.back(), LI, SE, DT, DeadInsts);
if (PHINode *WidePhi = Widener.CreateWideIV(Rewriter)) {
Changed = true;
LoopPhis.push_back(WidePhi);
}
}
- WideIVMap.clear();
- }
-}
-
-/// SimplifyCongruentIVs - Check for congruent phis in this loop header and
-/// replace them with their chosen representative.
-///
-void IndVarSimplify::SimplifyCongruentIVs(Loop *L) {
- DenseMap<const SCEV *, PHINode *> ExprToIVMap;
- for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I) {
- PHINode *Phi = cast<PHINode>(I);
- if (!SE->isSCEVable(Phi->getType()))
- continue;
-
- const SCEV *S = SE->getSCEV(Phi);
- std::pair<DenseMap<const SCEV *, PHINode *>::const_iterator, bool> Tmp =
- ExprToIVMap.insert(std::make_pair(S, Phi));
- if (Tmp.second)
- continue;
- PHINode *OrigPhi = Tmp.first->second;
-
- // If one phi derives from the other via GEPs, types may differ.
- if (OrigPhi->getType() != Phi->getType())
- continue;
-
- // Replacing the congruent phi is sufficient because acyclic redundancy
- // elimination, CSE/GVN, should handle the rest. However, once SCEV proves
- // that a phi is congruent, it's almost certain to be the head of an IV
- // user cycle that is isomorphic with the original phi. So it's worth
- // eagerly cleaning up the common case of a single IV increment.
- if (BasicBlock *LatchBlock = L->getLoopLatch()) {
- Instruction *OrigInc =
- cast<Instruction>(OrigPhi->getIncomingValueForBlock(LatchBlock));
- Instruction *IsomorphicInc =
- cast<Instruction>(Phi->getIncomingValueForBlock(LatchBlock));
- if (OrigInc != IsomorphicInc &&
- OrigInc->getType() == IsomorphicInc->getType() &&
- SE->getSCEV(OrigInc) == SE->getSCEV(IsomorphicInc) &&
- HoistStep(OrigInc, IsomorphicInc, DT)) {
- DEBUG(dbgs() << "INDVARS: Eliminated congruent iv.inc: "
- << *IsomorphicInc << '\n');
- IsomorphicInc->replaceAllUsesWith(OrigInc);
- DeadInsts.push_back(IsomorphicInc);
- }
- }
- DEBUG(dbgs() << "INDVARS: Eliminated congruent iv: " << *Phi << '\n');
- ++NumElimIV;
- Phi->replaceAllUsesWith(OrigPhi);
- DeadInsts.push_back(Phi);
}
}
/// BackedgeTakenInfo. If these expressions have not been reduced, then
/// expanding them may incur additional cost (albeit in the loop preheader).
static bool isHighCostExpansion(const SCEV *S, BranchInst *BI,
+ SmallPtrSet<const SCEV*, 8> &Processed,
ScalarEvolution *SE) {
+ if (!Processed.insert(S))
+ return false;
+
// If the backedge-taken count is a UDiv, it's very likely a UDiv that
// ScalarEvolution's HowFarToZero or HowManyLessThans produced to compute a
// precise expression, rather than a UDiv from the user's code. If we can't
if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
for (SCEVAddExpr::op_iterator I = Add->op_begin(), E = Add->op_end();
I != E; ++I) {
- if (isHighCostExpansion(*I, BI, SE))
+ if (isHighCostExpansion(*I, BI, Processed, SE))
return true;
}
return false;
if (isa<SCEVSMaxExpr>(S) || isa<SCEVUMaxExpr>(S))
return true;
- // If we haven't recognized an expensive SCEV patter, assume its an expression
- // produced by program code.
+ // If we haven't recognized an expensive SCEV pattern, assume it's an
+ // expression produced by program code.
return false;
}
/// canExpandBackedgeTakenCount - Return true if this loop's backedge taken
/// count expression can be safely and cheaply expanded into an instruction
/// sequence that can be used by LinearFunctionTestReplace.
+///
+/// TODO: This fails for pointer-type loop counters with greater than one byte
+/// strides, consequently preventing LFTR from running. For the purpose of LFTR
+/// we could skip this check in the case that the LFTR loop counter (chosen by
+/// FindLoopCounter) is also pointer type. Instead, we could directly convert
+/// the loop test to an inequality test by checking the target data's alignment
+/// of element types (given that the initial pointer value originates from or is
+/// used by ABI constrained operation, as opposed to inttoptr/ptrtoint).
+/// However, we don't yet have a strong motivation for converting loop tests
+/// into inequality tests.
static bool canExpandBackedgeTakenCount(Loop *L, ScalarEvolution *SE) {
const SCEV *BackedgeTakenCount = SE->getBackedgeTakenCount(L);
if (isa<SCEVCouldNotCompute>(BackedgeTakenCount) ||
if (!BI)
return false;
- if (isHighCostExpansion(BackedgeTakenCount, BI, SE))
+ SmallPtrSet<const SCEV*, 8> Processed;
+ if (isHighCostExpansion(BackedgeTakenCount, BI, Processed, SE))
return false;
return true;
/// FindLoopCounter - Find an affine IV in canonical form.
///
+/// BECount may be an i8* pointer type. The pointer difference is already
+/// valid count without scaling the address stride, so it remains a pointer
+/// expression as far as SCEV is concerned.
+///
/// FIXME: Accept -1 stride and set IVLimit = IVInit - BECount
///
/// FIXME: Accept non-unit stride as long as SCEV can reduce BECount * Stride.
static PHINode *
FindLoopCounter(Loop *L, const SCEV *BECount,
ScalarEvolution *SE, DominatorTree *DT, const TargetData *TD) {
- // I'm not sure how BECount could be a pointer type, but we definitely don't
- // want to LFTR that.
- if (BECount->getType()->isPointerTy())
- return 0;
-
uint64_t BCWidth = SE->getTypeSizeInBits(BECount->getType());
Value *Cond =
if (!SE->isSCEVable(Phi->getType()))
continue;
+ // Avoid comparing an integer IV against a pointer Limit.
+ if (BECount->getType()->isPointerTy() && !Phi->getType()->isPointerTy())
+ continue;
+
const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(Phi));
if (!AR || AR->getLoop() != L || !AR->isAffine())
continue;
return BestPhi;
}
+/// genLoopLimit - Help LinearFunctionTestReplace by generating a value that
+/// holds the RHS of the new loop test.
+static Value *genLoopLimit(PHINode *IndVar, const SCEV *IVCount, Loop *L,
+ SCEVExpander &Rewriter, ScalarEvolution *SE) {
+ const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(IndVar));
+ assert(AR && AR->getLoop() == L && AR->isAffine() && "bad loop counter");
+ const SCEV *IVInit = AR->getStart();
+
+ // IVInit may be a pointer while IVCount is an integer when FindLoopCounter
+ // finds a valid pointer IV. Sign extend BECount in order to materialize a
+ // GEP. Avoid running SCEVExpander on a new pointer value, instead reusing
+ // the existing GEPs whenever possible.
+ if (IndVar->getType()->isPointerTy()
+ && !IVCount->getType()->isPointerTy()) {
+
+ Type *OfsTy = SE->getEffectiveSCEVType(IVInit->getType());
+ const SCEV *IVOffset = SE->getTruncateOrSignExtend(IVCount, OfsTy);
+
+ // Expand the code for the iteration count.
+ assert(SE->isLoopInvariant(IVOffset, L) &&
+ "Computed iteration count is not loop invariant!");
+ BranchInst *BI = cast<BranchInst>(L->getExitingBlock()->getTerminator());
+ Value *GEPOffset = Rewriter.expandCodeFor(IVOffset, OfsTy, BI);
+
+ Value *GEPBase = IndVar->getIncomingValueForBlock(L->getLoopPreheader());
+ assert(AR->getStart() == SE->getSCEV(GEPBase) && "bad loop counter");
+ // We could handle pointer IVs other than i8*, but we need to compensate for
+ // gep index scaling. See canExpandBackedgeTakenCount comments.
+ assert(SE->getSizeOfExpr(
+ cast<PointerType>(GEPBase->getType())->getElementType())->isOne()
+ && "unit stride pointer IV must be i8*");
+
+ IRBuilder<> Builder(L->getLoopPreheader()->getTerminator());
+ return Builder.CreateGEP(GEPBase, GEPOffset, "lftr.limit");
+ }
+ else {
+ // In any other case, convert both IVInit and IVCount to integers before
+ // comparing. This may result in SCEV expension of pointers, but in practice
+ // SCEV will fold the pointer arithmetic away as such:
+ // BECount = (IVEnd - IVInit - 1) => IVLimit = IVInit (postinc).
+ //
+ // Valid Cases: (1) both integers is most common; (2) both may be pointers
+ // for simple memset-style loops; (3) IVInit is an integer and IVCount is a
+ // pointer may occur when enable-iv-rewrite generates a canonical IV on top
+ // of case #2.
+
+ const SCEV *IVLimit = 0;
+ // For unit stride, IVCount = Start + BECount with 2's complement overflow.
+ // For non-zero Start, compute IVCount here.
+ if (AR->getStart()->isZero())
+ IVLimit = IVCount;
+ else {
+ assert(AR->getStepRecurrence(*SE)->isOne() && "only handles unit stride");
+ const SCEV *IVInit = AR->getStart();
+
+ // For integer IVs, truncate the IV before computing IVInit + BECount.
+ if (SE->getTypeSizeInBits(IVInit->getType())
+ > SE->getTypeSizeInBits(IVCount->getType()))
+ IVInit = SE->getTruncateExpr(IVInit, IVCount->getType());
+
+ IVLimit = SE->getAddExpr(IVInit, IVCount);
+ }
+ // Expand the code for the iteration count.
+ BranchInst *BI = cast<BranchInst>(L->getExitingBlock()->getTerminator());
+ IRBuilder<> Builder(BI);
+ assert(SE->isLoopInvariant(IVLimit, L) &&
+ "Computed iteration count is not loop invariant!");
+ // Ensure that we generate the same type as IndVar, or a smaller integer
+ // type. In the presence of null pointer values, we have an integer type
+ // SCEV expression (IVInit) for a pointer type IV value (IndVar).
+ Type *LimitTy = IVCount->getType()->isPointerTy() ?
+ IndVar->getType() : IVCount->getType();
+ return Rewriter.expandCodeFor(IVLimit, LimitTy, BI);
+ }
+}
+
/// LinearFunctionTestReplace - This method rewrites the exit condition of the
/// loop to be a canonical != comparison against the incremented loop induction
/// variable. This pass is able to rewrite the exit tests of any loop where the
PHINode *IndVar,
SCEVExpander &Rewriter) {
assert(canExpandBackedgeTakenCount(L, SE) && "precondition");
- BranchInst *BI = cast<BranchInst>(L->getExitingBlock()->getTerminator());
// LFTR can ignore IV overflow and truncate to the width of
// BECount. This avoids materializing the add(zext(add)) expression.
Type *CntTy = !EnableIVRewrite ?
BackedgeTakenCount->getType() : IndVar->getType();
- const SCEV *IVLimit = BackedgeTakenCount;
+ const SCEV *IVCount = BackedgeTakenCount;
- // If the exiting block is not the same as the backedge block, we must compare
- // against the preincremented value, otherwise we prefer to compare against
- // the post-incremented value.
+ // If the exiting block is the same as the backedge block, we prefer to
+ // compare against the post-incremented value, otherwise we must compare
+ // against the preincremented value.
Value *CmpIndVar;
if (L->getExitingBlock() == L->getLoopLatch()) {
// Add one to the "backedge-taken" count to get the trip count.
// If this addition may overflow, we have to be more pessimistic and
// cast the induction variable before doing the add.
const SCEV *N =
- SE->getAddExpr(IVLimit, SE->getConstant(IVLimit->getType(), 1));
- if (CntTy == IVLimit->getType())
- IVLimit = N;
+ SE->getAddExpr(IVCount, SE->getConstant(IVCount->getType(), 1));
+ if (CntTy == IVCount->getType())
+ IVCount = N;
else {
- const SCEV *Zero = SE->getConstant(IVLimit->getType(), 0);
+ const SCEV *Zero = SE->getConstant(IVCount->getType(), 0);
if ((isa<SCEVConstant>(N) && !N->isZero()) ||
SE->isLoopEntryGuardedByCond(L, ICmpInst::ICMP_NE, N, Zero)) {
// No overflow. Cast the sum.
- IVLimit = SE->getTruncateOrZeroExtend(N, CntTy);
+ IVCount = SE->getTruncateOrZeroExtend(N, CntTy);
} else {
// Potential overflow. Cast before doing the add.
- IVLimit = SE->getTruncateOrZeroExtend(IVLimit, CntTy);
- IVLimit = SE->getAddExpr(IVLimit, SE->getConstant(CntTy, 1));
+ IVCount = SE->getTruncateOrZeroExtend(IVCount, CntTy);
+ IVCount = SE->getAddExpr(IVCount, SE->getConstant(CntTy, 1));
}
}
// The BackedgeTaken expression contains the number of times that the
// number of times the loop executes, so use the incremented indvar.
CmpIndVar = IndVar->getIncomingValueForBlock(L->getExitingBlock());
} else {
- // We have to use the preincremented value...
- IVLimit = SE->getTruncateOrZeroExtend(IVLimit, CntTy);
+ // We must use the preincremented value...
+ IVCount = SE->getTruncateOrZeroExtend(IVCount, CntTy);
CmpIndVar = IndVar;
}
- // For unit stride, IVLimit = Start + BECount with 2's complement overflow.
- // So for, non-zero start compute the IVLimit here.
- bool isPtrIV = false;
- Type *CmpTy = CntTy;
- const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(IndVar));
- assert(AR && AR->getLoop() == L && AR->isAffine() && "bad loop counter");
- if (!AR->getStart()->isZero()) {
- assert(AR->getStepRecurrence(*SE)->isOne() && "only handles unit stride");
- const SCEV *IVInit = AR->getStart();
-
- // For pointer types, sign extend BECount in order to materialize a GEP.
- // Note that for without EnableIVRewrite, we never run SCEVExpander on a
- // pointer type, because we must preserve the existing GEPs. Instead we
- // directly generate a GEP later.
- if (IVInit->getType()->isPointerTy()) {
- isPtrIV = true;
- CmpTy = SE->getEffectiveSCEVType(IVInit->getType());
- IVLimit = SE->getTruncateOrSignExtend(IVLimit, CmpTy);
- }
- // For integer types, truncate the IV before computing IVInit + BECount.
- else {
- if (SE->getTypeSizeInBits(IVInit->getType())
- > SE->getTypeSizeInBits(CmpTy))
- IVInit = SE->getTruncateExpr(IVInit, CmpTy);
-
- IVLimit = SE->getAddExpr(IVInit, IVLimit);
- }
- }
- // Expand the code for the iteration count.
- IRBuilder<> Builder(BI);
-
- assert(SE->isLoopInvariant(IVLimit, L) &&
- "Computed iteration count is not loop invariant!");
- Value *ExitCnt = Rewriter.expandCodeFor(IVLimit, CmpTy, BI);
-
- // Create a gep for IVInit + IVLimit from on an existing pointer base.
- assert(isPtrIV == IndVar->getType()->isPointerTy() &&
- "IndVar type must match IVInit type");
- if (isPtrIV) {
- Value *IVStart = IndVar->getIncomingValueForBlock(L->getLoopPreheader());
- assert(AR->getStart() == SE->getSCEV(IVStart) && "bad loop counter");
- assert(SE->getSizeOfExpr(
- cast<PointerType>(IVStart->getType())->getElementType())->isOne()
- && "unit stride pointer IV must be i8*");
-
- Builder.SetInsertPoint(L->getLoopPreheader()->getTerminator());
- ExitCnt = Builder.CreateGEP(IVStart, ExitCnt, "lftr.limit");
- Builder.SetInsertPoint(BI);
- }
+ Value *ExitCnt = genLoopLimit(IndVar, IVCount, L, Rewriter, SE);
+ assert(ExitCnt->getType()->isPointerTy() == IndVar->getType()->isPointerTy()
+ && "genLoopLimit missed a cast");
// Insert a new icmp_ne or icmp_eq instruction before the branch.
+ BranchInst *BI = cast<BranchInst>(L->getExitingBlock()->getTerminator());
ICmpInst::Predicate P;
if (L->contains(BI->getSuccessor(0)))
P = ICmpInst::ICMP_NE;
<< " op:\t"
<< (P == ICmpInst::ICMP_NE ? "!=" : "==") << "\n"
<< " RHS:\t" << *ExitCnt << "\n"
- << " Expr:\t" << *IVLimit << "\n");
+ << " IVCount:\t" << *IVCount << "\n");
+ IRBuilder<> Builder(BI);
if (SE->getTypeSizeInBits(CmpIndVar->getType())
- > SE->getTypeSizeInBits(CmpTy)) {
- CmpIndVar = Builder.CreateTrunc(CmpIndVar, CmpTy, "lftr.wideiv");
+ > SE->getTypeSizeInBits(ExitCnt->getType())) {
+ CmpIndVar = Builder.CreateTrunc(CmpIndVar, ExitCnt->getType(),
+ "lftr.wideiv");
}
Value *Cond = Builder.CreateICmp(P, CmpIndVar, ExitCnt, "exitcond");
if (isa<LandingPadInst>(I))
continue;
- // Don't sink static AllocaInsts out of the entry block, which would
- // turn them into dynamic allocas!
- if (AllocaInst *AI = dyn_cast<AllocaInst>(I))
- if (AI->isStaticAlloca())
- continue;
+ // Don't sink alloca: we never want to sink static alloca's out of the
+ // entry block, and correctly sinking dynamic alloca's requires
+ // checks for stacksave/stackrestore intrinsics.
+ // FIXME: Refactor this check somehow?
+ if (isa<AllocaInst>(I))
+ continue;
// Determine if there is a use in or before the loop (direct or
// otherwise).
// Create a rewriter object which we'll use to transform the code with.
SCEVExpander Rewriter(*SE, "indvars");
+#ifndef NDEBUG
+ Rewriter.setDebugType(DEBUG_TYPE);
+#endif
// Eliminate redundant IV users.
//
// Eliminate redundant IV cycles.
if (!EnableIVRewrite)
- SimplifyCongruentIVs(L);
+ NumElimIV += Rewriter.replaceCongruentIVs(L, DT, DeadInsts);
// Compute the type of the largest recurrence expression, and decide whether
// a canonical induction variable should be inserted.
projects / oota-llvm.git / blobdiff