//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "loop-reduce"
#include "llvm/Transforms/Scalar.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/Hashing.h"
#include <algorithm>
using namespace llvm;
+#define DEBUG_TYPE "loop-reduce"
+
/// MaxIVUsers is an arbitrary threshold that provides an early opportunitiy for
/// bail out. This threshold is far beyond the number of users that LSR can
/// conceivably solve, so it should not affect generated code, but catches the
int64_t UnfoldedOffset;
Formula()
- : BaseGV(0), BaseOffset(0), HasBaseReg(false), Scale(0), ScaledReg(0),
- UnfoldedOffset(0) {}
+ : BaseGV(nullptr), BaseOffset(0), HasBaseReg(false), Scale(0),
+ ScaledReg(nullptr), UnfoldedOffset(0) {}
void InitialMatch(const SCEV *S, Loop *L, ScalarEvolution &SE);
- unsigned getNumRegs() const;
+ size_t getNumRegs() const;
Type *getType() const;
void DeleteBaseReg(const SCEV *&S);
/// getNumRegs - Return the total number of register operands used by this
/// formula. This does not include register uses implied by non-constant
/// addrec strides.
-unsigned Formula::getNumRegs() const {
+size_t Formula::getNumRegs() const {
return !!ScaledReg + BaseRegs.size();
}
return !BaseRegs.empty() ? BaseRegs.front()->getType() :
ScaledReg ? ScaledReg->getType() :
BaseGV ? BaseGV->getType() :
- 0;
+ nullptr;
}
/// DeleteBaseReg - Delete the given base reg from the BaseRegs list.
// Check for a division of a constant by a constant.
if (const SCEVConstant *C = dyn_cast<SCEVConstant>(LHS)) {
if (!RC)
- return 0;
+ return nullptr;
const APInt &LA = C->getValue()->getValue();
const APInt &RA = RC->getValue()->getValue();
if (LA.srem(RA) != 0)
- return 0;
+ return nullptr;
return SE.getConstant(LA.sdiv(RA));
}
if (IgnoreSignificantBits || isAddRecSExtable(AR, SE)) {
const SCEV *Step = getExactSDiv(AR->getStepRecurrence(SE), RHS, SE,
IgnoreSignificantBits);
- if (!Step) return 0;
+ if (!Step) return nullptr;
const SCEV *Start = getExactSDiv(AR->getStart(), RHS, SE,
IgnoreSignificantBits);
- if (!Start) return 0;
+ if (!Start) return nullptr;
// FlagNW is independent of the start value, step direction, and is
// preserved with smaller magnitude steps.
// FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
return SE.getAddRecExpr(Start, Step, AR->getLoop(), SCEV::FlagAnyWrap);
}
- return 0;
+ return nullptr;
}
// Distribute the sdiv over add operands, if the add doesn't overflow.
I != E; ++I) {
const SCEV *Op = getExactSDiv(*I, RHS, SE,
IgnoreSignificantBits);
- if (!Op) return 0;
+ if (!Op) return nullptr;
Ops.push_back(Op);
}
return SE.getAddExpr(Ops);
}
- return 0;
+ return nullptr;
}
// Check for a multiply operand that we can pull RHS out of.
}
Ops.push_back(S);
}
- return Found ? SE.getMulExpr(Ops) : 0;
+ return Found ? SE.getMulExpr(Ops) : nullptr;
}
- return 0;
+ return nullptr;
}
// Otherwise we don't know.
- return 0;
+ return nullptr;
}
/// ExtractImmediate - If S involves the addition of a constant integer value,
SCEV::FlagAnyWrap);
return Result;
}
- return 0;
+ return nullptr;
}
/// isAddressUse - Returns true if the specified instruction is using the
Value *V = DeadInsts.pop_back_val();
Instruction *I = dyn_cast_or_null<Instruction>(V);
- if (I == 0 || !isInstructionTriviallyDead(I))
+ if (!I || !isInstructionTriviallyDead(I))
continue;
for (User::op_iterator OI = I->op_begin(), E = I->op_end(); OI != E; ++OI)
if (Instruction *U = dyn_cast<Instruction>(*OI)) {
- *OI = 0;
+ *OI = nullptr;
if (U->use_empty())
DeadInsts.push_back(U);
}
const SmallVectorImpl<int64_t> &Offsets,
ScalarEvolution &SE, DominatorTree &DT,
const LSRUse &LU,
- SmallPtrSet<const SCEV *, 16> *LoserRegs = 0);
+ SmallPtrSet<const SCEV *, 16> *LoserRegs = nullptr);
void print(raw_ostream &OS) const;
void dump() const;
}
LSRFixup::LSRFixup()
- : UserInst(0), OperandValToReplace(0), LUIdx(~size_t(0)), Offset(0) {}
+ : UserInst(nullptr), OperandValToReplace(nullptr), LUIdx(~size_t(0)),
+ Offset(0) {}
/// isUseFullyOutsideLoop - Test whether this fixup always uses its
/// value outside of the given loop.
MaxOffset(INT64_MIN),
AllFixupsOutsideLoop(true),
RigidFormula(false),
- WidestFixupType(0) {}
+ WidestFixupType(nullptr) {}
bool HasFormulaWithSameRegs(const Formula &F) const;
bool InsertFormula(const Formula &F);
SmallVector<IVInc,1> Incs;
const SCEV *ExprBase;
- IVChain() : ExprBase(0) {}
+ IVChain() : ExprBase(nullptr) {}
IVChain(const IVInc &Head, const SCEV *Base)
: Incs(1, Head), ExprBase(Base) {}
IVUsers::const_iterator CandidateUI = UI;
++UI;
Instruction *ShadowUse = CandidateUI->getUser();
- Type *DestTy = 0;
+ Type *DestTy = nullptr;
bool IsSigned = false;
/* If shadow use is a int->float cast then insert a second IV
continue;
/* Initialize new IV, double d = 0.0 in above example. */
- ConstantInt *C = 0;
+ ConstantInt *C = nullptr;
if (Incr->getOperand(0) == PH)
C = dyn_cast<ConstantInt>(Incr->getOperand(1));
else if (Incr->getOperand(1) == PH)
// for ICMP_ULE here because the comparison would be with zero, which
// isn't interesting.
CmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE;
- const SCEVNAryExpr *Max = 0;
+ const SCEVNAryExpr *Max = nullptr;
if (const SCEVSMaxExpr *S = dyn_cast<SCEVSMaxExpr>(BackedgeTakenCount)) {
Pred = ICmpInst::ICMP_SLE;
Max = S;
// Check the right operand of the select, and remember it, as it will
// be used in the new comparison instruction.
- Value *NewRHS = 0;
+ Value *NewRHS = nullptr;
if (ICmpInst::isTrueWhenEqual(Pred)) {
// Look for n+1, and grab n.
if (AddOperator *BO = dyn_cast<AddOperator>(Sel->getOperand(1)))
continue;
// Search IVUsesByStride to find Cond's IVUse if there is one.
- IVStrideUse *CondUse = 0;
+ IVStrideUse *CondUse = nullptr;
ICmpInst *Cond = cast<ICmpInst>(TermBr->getCondition());
if (!FindIVUserForCond(Cond, CondUse))
continue;
// Check for possible scaled-address reuse.
Type *AccessTy = getAccessType(UI->getUser());
int64_t Scale = C->getSExtValue();
- if (TTI.isLegalAddressingMode(AccessTy, /*BaseGV=*/ 0,
+ if (TTI.isLegalAddressingMode(AccessTy, /*BaseGV=*/ nullptr,
/*BaseOffset=*/ 0,
/*HasBaseReg=*/ false, Scale))
goto decline_post_inc;
Scale = -Scale;
- if (TTI.isLegalAddressingMode(AccessTy, /*BaseGV=*/ 0,
+ if (TTI.isLegalAddressingMode(AccessTy, /*BaseGV=*/ nullptr,
/*BaseOffset=*/ 0,
/*HasBaseReg=*/ false, Scale))
goto decline_post_inc;
return false;
// Conservatively assume HasBaseReg is true for now.
if (NewOffset < LU.MinOffset) {
- if (!isAlwaysFoldable(TTI, Kind, AccessTy, /*BaseGV=*/ 0,
+ if (!isAlwaysFoldable(TTI, Kind, AccessTy, /*BaseGV=*/ nullptr,
LU.MaxOffset - NewOffset, HasBaseReg))
return false;
NewMinOffset = NewOffset;
} else if (NewOffset > LU.MaxOffset) {
- if (!isAlwaysFoldable(TTI, Kind, AccessTy, /*BaseGV=*/ 0,
+ if (!isAlwaysFoldable(TTI, Kind, AccessTy, /*BaseGV=*/ nullptr,
NewOffset - LU.MinOffset, HasBaseReg))
return false;
NewMaxOffset = NewOffset;
int64_t Offset = ExtractImmediate(Expr, SE);
// Basic uses can't accept any offset, for example.
- if (!isAlwaysFoldable(TTI, Kind, AccessTy, /*BaseGV=*/ 0,
+ if (!isAlwaysFoldable(TTI, Kind, AccessTy, /*BaseGV=*/ nullptr,
Offset, /*HasBaseReg=*/ true)) {
Expr = Copy;
Offset = 0;
}
// Nothing looked good.
- return 0;
+ return nullptr;
}
void LSRInstance::CollectInterestingTypesAndFactors() {
default: // uncluding scUnknown.
return S;
case scConstant:
- return 0;
+ return nullptr;
case scTruncate:
return getExprBase(cast<SCEVTruncateExpr>(S)->getOperand());
case scZeroExtend:
&& SE.getSCEV(Chain.tailUserInst()) == Chain.Incs[0].IncExpr) {
--cost;
}
- const SCEV *LastIncExpr = 0;
+ const SCEV *LastIncExpr = nullptr;
unsigned NumConstIncrements = 0;
unsigned NumVarIncrements = 0;
unsigned NumReusedIncrements = 0;
// Visit all existing chains. Check if its IVOper can be computed as a
// profitable loop invariant increment from the last link in the Chain.
unsigned ChainIdx = 0, NChains = IVChainVec.size();
- const SCEV *LastIncExpr = 0;
+ const SCEV *LastIncExpr = nullptr;
for (; ChainIdx < NChains; ++ChainIdx) {
IVChain &Chain = IVChainVec[ChainIdx];
int64_t IncOffset = IncConst->getValue()->getSExtValue();
if (!isAlwaysFoldable(TTI, LSRUse::Address,
- getAccessType(UserInst), /*BaseGV=*/ 0,
+ getAccessType(UserInst), /*BaseGV=*/ nullptr,
IncOffset, /*HaseBaseReg=*/ false))
return false;
// findIVOperand returns IVOpEnd if it can no longer find a valid IV user.
User::op_iterator IVOpIter = findIVOperand(Head.UserInst->op_begin(),
IVOpEnd, L, SE);
- Value *IVSrc = 0;
+ Value *IVSrc = nullptr;
while (IVOpIter != IVOpEnd) {
IVSrc = getWideOperand(*IVOpIter);
DEBUG(dbgs() << "Generate chain at: " << *IVSrc << "\n");
Type *IVTy = IVSrc->getType();
Type *IntTy = SE.getEffectiveSCEVType(IVTy);
- const SCEV *LeftOverExpr = 0;
+ const SCEV *LeftOverExpr = nullptr;
for (IVChain::const_iterator IncI = Chain.begin(),
IncE = Chain.end(); IncI != IncE; ++IncI) {
TTI)) {
assert(IVTy == IVOper->getType() && "inconsistent IV increment type");
IVSrc = IVOper;
- LeftOverExpr = 0;
+ LeftOverExpr = nullptr;
}
}
Type *OperTy = IncI->IVOperand->getType();
LF.PostIncLoops = UI->getPostIncLoops();
LSRUse::KindType Kind = LSRUse::Basic;
- Type *AccessTy = 0;
+ Type *AccessTy = nullptr;
if (isAddressUse(LF.UserInst, LF.OperandValToReplace)) {
Kind = LSRUse::Address;
AccessTy = getAccessType(LF.UserInst);
if (SE.isLoopInvariant(N, L) && isSafeToExpand(N, SE)) {
// S is normalized, so normalize N before folding it into S
// to keep the result normalized.
- N = TransformForPostIncUse(Normalize, N, CI, 0,
+ N = TransformForPostIncUse(Normalize, N, CI, nullptr,
LF.PostIncLoops, SE, DT);
Kind = LSRUse::ICmpZero;
S = SE.getMinusSCEV(N, S);
LSRFixup &LF = getNewFixup();
LF.UserInst = const_cast<Instruction *>(UserInst);
LF.OperandValToReplace = U;
- std::pair<size_t, int64_t> P = getUse(S, LSRUse::Basic, 0);
+ std::pair<size_t, int64_t> P = getUse(S, LSRUse::Basic, nullptr);
LF.LUIdx = P.first;
LF.Offset = P.second;
LSRUse &LU = Uses[LF.LUIdx];
if (Remainder)
Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder);
}
- return 0;
+ return nullptr;
} else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
// Split a non-zero base out of an addrec.
if (AR->getStart()->isZero())
// does not pertain to this loop.
if (Remainder && (AR->getLoop() == L || !isa<SCEVAddRecExpr>(Remainder))) {
Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder);
- Remainder = 0;
+ Remainder = nullptr;
}
if (Remainder != AR->getStart()) {
if (!Remainder)
CollectSubexprs(Mul->getOperand(1), C, Ops, L, SE, Depth+1);
if (Remainder)
Ops.push_back(SE.getMulExpr(C, Remainder));
- return 0;
+ return nullptr;
}
}
return S;
const SCEV *BaseReg = Base.BaseRegs[i];
SmallVector<const SCEV *, 8> AddOps;
- const SCEV *Remainder = CollectSubexprs(BaseReg, 0, AddOps, L, SE);
+ const SCEV *Remainder = CollectSubexprs(BaseReg, nullptr, AddOps, L, SE);
if (Remainder)
AddOps.push_back(Remainder);
// Pick the register which is used by the most LSRUses, which is likely
// to be a good reuse register candidate.
- const SCEV *Best = 0;
+ const SCEV *Best = nullptr;
unsigned BestNum = 0;
for (RegUseTracker::const_iterator I = RegUses.begin(), E = RegUses.end();
I != E; ++I) {
E = LU.Formulae.end(); I != E; ++I) {
const Formula &F = *I;
- // Ignore formulae which do not use any of the required registers.
- bool SatisfiedReqReg = true;
+ // Ignore formulae which may not be ideal in terms of register reuse of
+ // ReqRegs. The formula should use all required registers before
+ // introducing new ones.
+ int NumReqRegsToFind = std::min(F.getNumRegs(), ReqRegs.size());
for (SmallSetVector<const SCEV *, 4>::const_iterator J = ReqRegs.begin(),
JE = ReqRegs.end(); J != JE; ++J) {
const SCEV *Reg = *J;
- if ((!F.ScaledReg || F.ScaledReg != Reg) &&
- std::find(F.BaseRegs.begin(), F.BaseRegs.end(), Reg) ==
+ if ((F.ScaledReg && F.ScaledReg == Reg) ||
+ std::find(F.BaseRegs.begin(), F.BaseRegs.end(), Reg) !=
F.BaseRegs.end()) {
- SatisfiedReqReg = false;
- break;
+ --NumReqRegsToFind;
+ if (NumReqRegsToFind == 0)
+ break;
}
}
- if (!SatisfiedReqReg) {
+ if (NumReqRegsToFind != 0) {
// If none of the formulae satisfied the required registers, then we could
// clear ReqRegs and try again. Currently, we simply give up in this case.
continue;
}
bool AllDominate = true;
- Instruction *BetterPos = 0;
+ Instruction *BetterPos = nullptr;
Instruction *Tentative = IDom->getTerminator();
for (SmallVectorImpl<Instruction *>::const_iterator I = Inputs.begin(),
E = Inputs.end(); I != E; ++I) {
LF.UserInst, LF.OperandValToReplace,
Loops, SE, DT);
- Ops.push_back(SE.getUnknown(Rewriter.expandCodeFor(Reg, 0, IP)));
+ Ops.push_back(SE.getUnknown(Rewriter.expandCodeFor(Reg, nullptr, IP)));
}
// Expand the ScaledReg portion.
- Value *ICmpScaledV = 0;
+ Value *ICmpScaledV = nullptr;
if (F.Scale != 0) {
const SCEV *ScaledS = F.ScaledReg;
// of the icmp.
assert(F.Scale == -1 &&
"The only scale supported by ICmpZero uses is -1!");
- ICmpScaledV = Rewriter.expandCodeFor(ScaledS, 0, IP);
+ ICmpScaledV = Rewriter.expandCodeFor(ScaledS, nullptr, IP);
} else {
// Otherwise just expand the scaled register and an explicit scale,
// which is expected to be matched as part of the address.
Ops.clear();
Ops.push_back(SE.getUnknown(FullV));
}
- ScaledS = SE.getUnknown(Rewriter.expandCodeFor(ScaledS, 0, IP));
+ ScaledS = SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr, IP));
ScaledS = SE.getMulExpr(ScaledS,
SE.getConstant(ScaledS->getType(), F.Scale));
Ops.push_back(ScaledS);
Loop *PNLoop = LI.getLoopFor(Parent);
if (!PNLoop || Parent != PNLoop->getHeader()) {
// Split the critical edge.
- BasicBlock *NewBB = 0;
+ BasicBlock *NewBB = nullptr;
if (!Parent->isLandingPad()) {
NewBB = SplitCriticalEdge(BB, Parent, P,
/*MergeIdenticalEdges=*/true,
}
std::pair<DenseMap<BasicBlock *, Value *>::iterator, bool> Pair =
- Inserted.insert(std::make_pair(BB, static_cast<Value *>(0)));
+ Inserted.insert(std::make_pair(BB, static_cast<Value *>(nullptr)));
if (!Pair.second)
PN->setIncomingValue(i, Pair.first->second);
else {
DT(P->getAnalysis<DominatorTreeWrapperPass>().getDomTree()),
LI(P->getAnalysis<LoopInfo>()),
TTI(P->getAnalysis<TargetTransformInfo>()), L(L), Changed(false),
- IVIncInsertPos(0) {
+ IVIncInsertPos(nullptr) {
// If LoopSimplify form is not available, stay out of trouble.
if (!L->isLoopSimplifyForm())
return;
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