X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FTransforms%2FScalar%2FLoopStrengthReduce.cpp;h=14274296de7da2bebf3a69d6370dcf64203a639b;hb=7d9f2b93a356aa89186522bd61c5c565718ff555;hp=3341cb386d647ed0efb0908e3dc304f6576bc944;hpb=940bd3e23666b44797270b0b0cd0609f74166980;p=oota-llvm.git diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp index 3341cb386d6..14274296de7 100644 --- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -33,15 +33,10 @@ // the value of the induction variable after the increment. The other common // case of post-increment users is users outside the loop. // -// TODO: More sophistication in the way Formulae are generated. +// TODO: More sophistication in the way Formulae are generated and filtered. // // TODO: Handle multiple loops at a time. // -// TODO: test/CodeGen/X86/full-lsr.ll should get full lsr. The problem is -// that {0,+,1}<%bb> is getting picked first because all 7 uses can -// use it, and while it's a pretty good solution, it means that LSR -// doesn't look further to find an even better solution. -// // TODO: Should TargetLowering::AddrMode::BaseGV be changed to a ConstantExpr // instead of a GlobalValue? // @@ -72,6 +67,7 @@ #include "llvm/Transforms/Utils/Local.h" #include "llvm/ADT/SmallBitVector.h" #include "llvm/ADT/SetVector.h" +#include "llvm/ADT/DenseSet.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ValueHandle.h" #include "llvm/Support/raw_ostream.h" @@ -81,58 +77,12 @@ using namespace llvm; namespace { -// Constant strides come first which in turns are sorted by their absolute -// values. If absolute values are the same, then positive strides comes first. -// e.g. -// 4, -1, X, 1, 2 ==> 1, -1, 2, 4, X -struct StrideCompare { - const ScalarEvolution &SE; - explicit StrideCompare(const ScalarEvolution &se) : SE(se) {} - - bool operator()(const SCEV *const &LHS, const SCEV *const &RHS) const { - const SCEVConstant *LHSC = dyn_cast(LHS); - const SCEVConstant *RHSC = dyn_cast(RHS); - if (LHSC && RHSC) { - unsigned BitWidth = std::max(SE.getTypeSizeInBits(LHS->getType()), - SE.getTypeSizeInBits(RHS->getType())); - APInt LV = LHSC->getValue()->getValue(); - APInt RV = RHSC->getValue()->getValue(); - LV.sextOrTrunc(BitWidth); - RV.sextOrTrunc(BitWidth); - APInt ALV = LV.abs(); - APInt ARV = RV.abs(); - if (ALV == ARV) { - if (LV != RV) - return LV.sgt(RV); - } else { - return ALV.ult(ARV); - } - - // If it's the same value but different type, sort by bit width so - // that we emit larger induction variables before smaller - // ones, letting the smaller be re-written in terms of larger ones. - return SE.getTypeSizeInBits(RHS->getType()) < - SE.getTypeSizeInBits(LHS->getType()); - } - return LHSC && !RHSC; - } -}; - -/// RegSortData - This class holds data which is used to order reuse -/// candidates. +/// RegSortData - This class holds data which is used to order reuse candidates. class RegSortData { public: - /// Bits - This represents the set of LSRUses (by index) which reference a - /// particular register. - SmallBitVector Bits; - - /// MaxComplexity - This represents the greatest complexity (see the comments - /// on Formula::getComplexity) seen with a particular register. - uint32_t MaxComplexity; - - /// Index - This holds an arbitrary value used as a last-resort tie breaker - /// to ensure deterministic behavior. - unsigned Index; + /// UsedByIndices - This represents the set of LSRUse indices which reference + /// a particular register. + SmallBitVector UsedByIndices; RegSortData() {} @@ -143,10 +93,7 @@ public: } void RegSortData::print(raw_ostream &OS) const { - OS << "[NumUses=" << Bits.count() - << ", MaxComplexity="; - OS.write_hex(MaxComplexity); - OS << ", Index=" << Index << ']'; + OS << "[NumUses=" << UsedByIndices.count() << ']'; } void RegSortData::dump() const { @@ -155,131 +102,71 @@ void RegSortData::dump() const { namespace { -/// RegCount - This is a helper class to sort a given set of registers -/// according to associated RegSortData values. -class RegCount { -public: - const SCEV *Reg; - RegSortData Sort; - - RegCount(const SCEV *R, const RegSortData &RSD) - : Reg(R), Sort(RSD) {} - - // Sort by count. Returning true means the register is preferred. - bool operator<(const RegCount &Other) const { - // Sort by the number of unique uses of this register. - unsigned A = Sort.Bits.count(); - unsigned B = Other.Sort.Bits.count(); - if (A != B) return A > B; - - if (const SCEVAddRecExpr *AR = dyn_cast(Reg)) { - const SCEVAddRecExpr *BR = dyn_cast(Other.Reg); - // AddRecs have higher priority than other things. - if (!BR) return true; - - // Prefer affine values. - if (AR->isAffine() != BR->isAffine()) - return AR->isAffine(); - - const Loop *AL = AR->getLoop(); - const Loop *BL = BR->getLoop(); - if (AL != BL) { - unsigned ADepth = AL->getLoopDepth(); - unsigned BDepth = BL->getLoopDepth(); - // Prefer a less deeply nested addrec. - if (ADepth != BDepth) - return ADepth < BDepth; - - // Different loops at the same depth; do something arbitrary. - BasicBlock *AH = AL->getHeader(); - BasicBlock *BH = BL->getHeader(); - for (Function::iterator I = AH, E = AH->getParent()->end(); I != E; ++I) - if (&*I == BH) return true; - return false; - } +/// RegUseTracker - Map register candidates to information about how they are +/// used. +class RegUseTracker { + typedef DenseMap RegUsesTy; - // Sort addrecs by stride. - const SCEV *AStep = AR->getOperand(1); - const SCEV *BStep = BR->getOperand(1); - if (AStep != BStep) { - if (const SCEVConstant *AC = dyn_cast(AStep)) { - const SCEVConstant *BC = dyn_cast(BStep); - if (!BC) return true; - // Arbitrarily prefer wider registers. - if (AC->getValue()->getValue().getBitWidth() != - BC->getValue()->getValue().getBitWidth()) - return AC->getValue()->getValue().getBitWidth() > - BC->getValue()->getValue().getBitWidth(); - // Ignore the sign bit, assuming that striding by a negative value - // is just as easy as by a positive value. - // Prefer the addrec with the lesser absolute value stride, as it - // will allow uses to have simpler addressing modes. - return AC->getValue()->getValue().abs() - .ult(BC->getValue()->getValue().abs()); - } - } + RegUsesTy RegUses; + SmallVector RegSequence; - // Then sort by the register which will permit the simplest uses. - // This is a heuristic; currently we only track the most complex use as a - // representative. - if (Sort.MaxComplexity != Other.Sort.MaxComplexity) - return Sort.MaxComplexity < Other.Sort.MaxComplexity; - - // Then sort them by their start values. - const SCEV *AStart = AR->getStart(); - const SCEV *BStart = BR->getStart(); - if (AStart != BStart) { - if (const SCEVConstant *AC = dyn_cast(AStart)) { - const SCEVConstant *BC = dyn_cast(BStart); - if (!BC) return true; - // Arbitrarily prefer wider registers. - if (AC->getValue()->getValue().getBitWidth() != - BC->getValue()->getValue().getBitWidth()) - return AC->getValue()->getValue().getBitWidth() > - BC->getValue()->getValue().getBitWidth(); - // Prefer positive over negative if the absolute values are the same. - if (AC->getValue()->getValue().abs() == - BC->getValue()->getValue().abs()) - return AC->getValue()->getValue().isStrictlyPositive(); - // Prefer the addrec with the lesser absolute value start. - return AC->getValue()->getValue().abs() - .ult(BC->getValue()->getValue().abs()); - } - } - } else { - // AddRecs have higher priority than other things. - if (isa(Other.Reg)) return false; - // Sort by the register which will permit the simplest uses. - // This is a heuristic; currently we only track the most complex use as a - // representative. - if (Sort.MaxComplexity != Other.Sort.MaxComplexity) - return Sort.MaxComplexity < Other.Sort.MaxComplexity; - } +public: + void CountRegister(const SCEV *Reg, size_t LUIdx); + bool isRegUsedByUsesOtherThan(const SCEV *Reg, size_t LUIdx) const; - // Tie-breaker: the arbitrary index, to ensure a reliable ordering. - return Sort.Index < Other.Sort.Index; - } + const SmallBitVector &getUsedByIndices(const SCEV *Reg) const; - void print(raw_ostream &OS) const; - void dump() const; + void clear(); + + typedef SmallVectorImpl::iterator iterator; + typedef SmallVectorImpl::const_iterator const_iterator; + iterator begin() { return RegSequence.begin(); } + iterator end() { return RegSequence.end(); } + const_iterator begin() const { return RegSequence.begin(); } + const_iterator end() const { return RegSequence.end(); } }; } -void RegCount::print(raw_ostream &OS) const { - OS << *Reg << ':'; - Sort.print(OS); +void +RegUseTracker::CountRegister(const SCEV *Reg, size_t LUIdx) { + std::pair Pair = + RegUses.insert(std::make_pair(Reg, RegSortData())); + RegSortData &RSD = Pair.first->second; + if (Pair.second) + RegSequence.push_back(Reg); + RSD.UsedByIndices.resize(std::max(RSD.UsedByIndices.size(), LUIdx + 1)); + RSD.UsedByIndices.set(LUIdx); } -void RegCount::dump() const { - print(errs()); errs() << '\n'; +bool +RegUseTracker::isRegUsedByUsesOtherThan(const SCEV *Reg, size_t LUIdx) const { + if (!RegUses.count(Reg)) return false; + const SmallBitVector &UsedByIndices = + RegUses.find(Reg)->second.UsedByIndices; + int i = UsedByIndices.find_first(); + if (i == -1) return false; + if ((size_t)i != LUIdx) return true; + return UsedByIndices.find_next(i) != -1; +} + +const SmallBitVector &RegUseTracker::getUsedByIndices(const SCEV *Reg) const { + RegUsesTy::const_iterator I = RegUses.find(Reg); + assert(I != RegUses.end() && "Unknown register!"); + return I->second.UsedByIndices; +} + +void RegUseTracker::clear() { + RegUses.clear(); + RegSequence.clear(); } namespace { /// Formula - This class holds information that describes a formula for -/// satisfying a use. It may include broken-out immediates and scaled registers. +/// computing satisfying a use. It may include broken-out immediates and scaled +/// registers. struct Formula { /// AM - This is used to represent complex addressing, as well as other kinds /// of interesting uses. @@ -295,42 +182,15 @@ struct Formula { Formula() : ScaledReg(0) {} - unsigned getNumRegs() const; - uint32_t getComplexity() const; - const Type *getType() const; - void InitialMatch(const SCEV *S, Loop *L, ScalarEvolution &SE, DominatorTree &DT); - /// referencesReg - Test if this formula references the given register. - bool referencesReg(const SCEV *S) const { - return S == ScaledReg || - std::find(BaseRegs.begin(), BaseRegs.end(), S) != BaseRegs.end(); - } - - bool operator==(const Formula &Other) const { - return BaseRegs == Other.BaseRegs && - ScaledReg == Other.ScaledReg && - AM.Scale == Other.AM.Scale && - AM.BaseOffs == Other.AM.BaseOffs && - AM.BaseGV == Other.AM.BaseGV; - } - - // This sorts at least partially based on host pointer values which are - // not deterministic, so it is only usable for uniqification. - bool operator<(const Formula &Other) const { - if (BaseRegs != Other.BaseRegs) - return BaseRegs < Other.BaseRegs; - if (ScaledReg != Other.ScaledReg) - return ScaledReg < Other.ScaledReg; - if (AM.Scale != Other.AM.Scale) - return AM.Scale < Other.AM.Scale; - if (AM.BaseOffs != Other.AM.BaseOffs) - return AM.BaseOffs < Other.AM.BaseOffs; - if (AM.BaseGV != Other.AM.BaseGV) - return AM.BaseGV < Other.AM.BaseGV; - return false; - } + unsigned getNumRegs() const; + const Type *getType() const; + + bool referencesReg(const SCEV *S) const; + bool hasRegsUsedByUsesOtherThan(size_t LUIdx, + const RegUseTracker &RegUses) const; void print(raw_ostream &OS) const; void dump() const; @@ -338,63 +198,7 @@ struct Formula { } -/// 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 { - return !!ScaledReg + BaseRegs.size(); -} - -/// getComplexity - Return an oversimplified value indicating the complexity -/// of this formula. This is used as a tie-breaker in choosing register -/// preferences. -uint32_t Formula::getComplexity() const { - // Encode the information in a uint32_t so that comparing with operator< - // will be interesting. - return - // Most significant, the number of registers. This saturates because we - // need the bits, and because beyond a few hundred it doesn't really matter. - (std::min(getNumRegs(), (1u<<15)-1) << 17) | - // Having multiple base regs is worse than having a base reg and a scale. - ((BaseRegs.size() > 1) << 16) | - // Scale absolute value. - ((AM.Scale != 0 ? (Log2_64(abs64(AM.Scale)) + 1) : 0u) << 9) | - // Scale sign, which is less significant than the absolute value. - ((AM.Scale < 0) << 8) | - // Offset absolute value. - ((AM.BaseOffs != 0 ? (Log2_64(abs64(AM.BaseOffs)) + 1) : 0u) << 1) | - // If a GV is present, treat it like a maximal offset. - ((AM.BaseGV ? ((1u<<7)-1) : 0) << 1) | - // Offset sign, which is less significant than the absolute offset. - ((AM.BaseOffs < 0) << 0); -} - -/// getType - Return the type of this formula, if it has one, or null -/// otherwise. This type is meaningless except for the bit size. -const Type *Formula::getType() const { - return !BaseRegs.empty() ? BaseRegs.front()->getType() : - ScaledReg ? ScaledReg->getType() : - AM.BaseGV ? AM.BaseGV->getType() : - 0; -} - -namespace { - -/// ComplexitySorter - A predicate which orders Formulae by the number of -/// registers they contain. -struct ComplexitySorter { - bool operator()(const Formula &LHS, const Formula &RHS) const { - unsigned L = LHS.getNumRegs(); - unsigned R = RHS.getNumRegs(); - if (L != R) return L < R; - - return LHS.getComplexity() < RHS.getComplexity(); - } -}; - -} - -/// DoInitialMatch - Recurrsion helper for InitialMatch. +/// DoInitialMatch - Recursion helper for InitialMatch. static void DoInitialMatch(const SCEV *S, Loop *L, SmallVectorImpl &Good, SmallVectorImpl &Bad, @@ -414,7 +218,7 @@ static void DoInitialMatch(const SCEV *S, Loop *L, } // Look at addrec operands. - if (const SCEVAddRecExpr *AR = dyn_cast(S)) { + if (const SCEVAddRecExpr *AR = dyn_cast(S)) if (!AR->getStart()->isZero()) { DoInitialMatch(AR->getStart(), L, Good, Bad, SE, DT); DoInitialMatch(SE.getAddRecExpr(SE.getIntegerSCEV(0, AR->getType()), @@ -423,7 +227,6 @@ static void DoInitialMatch(const SCEV *S, Loop *L, L, Good, Bad, SE, DT); return; } - } // Handle a multiplication by -1 (negation) if it didn't fold. if (const SCEVMulExpr *Mul = dyn_cast(S)) @@ -468,6 +271,42 @@ void Formula::InitialMatch(const SCEV *S, Loop *L, } } +/// 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 { + return !!ScaledReg + BaseRegs.size(); +} + +/// getType - Return the type of this formula, if it has one, or null +/// otherwise. This type is meaningless except for the bit size. +const Type *Formula::getType() const { + return !BaseRegs.empty() ? BaseRegs.front()->getType() : + ScaledReg ? ScaledReg->getType() : + AM.BaseGV ? AM.BaseGV->getType() : + 0; +} + +/// referencesReg - Test if this formula references the given register. +bool Formula::referencesReg(const SCEV *S) const { + return S == ScaledReg || + std::find(BaseRegs.begin(), BaseRegs.end(), S) != BaseRegs.end(); +} + +/// hasRegsUsedByUsesOtherThan - Test whether this formula uses registers +/// which are used by uses other than the use with the given index. +bool Formula::hasRegsUsedByUsesOtherThan(size_t LUIdx, + const RegUseTracker &RegUses) const { + if (ScaledReg) + if (RegUses.isRegUsedByUsesOtherThan(ScaledReg, LUIdx)) + return true; + for (SmallVectorImpl::const_iterator I = BaseRegs.begin(), + E = BaseRegs.end(); I != E; ++I) + if (RegUses.isRegUsedByUsesOtherThan(*I, LUIdx)) + return true; + return false; +} + void Formula::print(raw_ostream &OS) const { bool First = true; if (AM.BaseGV) { @@ -481,9 +320,7 @@ void Formula::print(raw_ostream &OS) const { for (SmallVectorImpl::const_iterator I = BaseRegs.begin(), E = BaseRegs.end(); I != E; ++I) { if (!First) OS << " + "; else First = false; - OS << "reg("; - OS << **I; - OS << ")"; + OS << "reg(" << **I << ')'; } if (AM.Scale != 0) { if (!First) OS << " + "; else First = false; @@ -492,7 +329,7 @@ void Formula::print(raw_ostream &OS) const { OS << *ScaledReg; else OS << ""; - OS << ")"; + OS << ')'; } } @@ -500,14 +337,42 @@ void Formula::dump() const { print(errs()); errs() << '\n'; } -/// getSDiv - Return an expression for LHS /s RHS, if it can be determined, -/// or null otherwise. If IgnoreSignificantBits is true, expressions like -/// (X * Y) /s Y are simplified to Y, ignoring that the multiplication may -/// overflow, which is useful when the result will be used in a context where -/// the most significant bits are ignored. -static const SCEV *getSDiv(const SCEV *LHS, const SCEV *RHS, - ScalarEvolution &SE, - bool IgnoreSignificantBits = false) { +/// isAddRecSExtable - Return true if the given addrec can be sign-extended +/// without changing its value. +static bool isAddRecSExtable(const SCEVAddRecExpr *AR, ScalarEvolution &SE) { + const Type *WideTy = + IntegerType::get(SE.getContext(), + SE.getTypeSizeInBits(AR->getType()) + 1); + return isa(SE.getSignExtendExpr(AR, WideTy)); +} + +/// isAddSExtable - Return true if the given add can be sign-extended +/// without changing its value. +static bool isAddSExtable(const SCEVAddExpr *A, ScalarEvolution &SE) { + const Type *WideTy = + IntegerType::get(SE.getContext(), + SE.getTypeSizeInBits(A->getType()) + 1); + return isa(SE.getSignExtendExpr(A, WideTy)); +} + +/// isMulSExtable - Return true if the given add can be sign-extended +/// without changing its value. +static bool isMulSExtable(const SCEVMulExpr *A, ScalarEvolution &SE) { + const Type *WideTy = + IntegerType::get(SE.getContext(), + SE.getTypeSizeInBits(A->getType()) + 1); + return isa(SE.getSignExtendExpr(A, WideTy)); +} + +/// getExactSDiv - Return an expression for LHS /s RHS, if it can be determined +/// and if the remainder is known to be zero, or null otherwise. If +/// IgnoreSignificantBits is true, expressions like (X * Y) /s Y are simplified +/// to Y, ignoring that the multiplication may overflow, which is useful when +/// the result will be used in a context where the most significant bits are +/// ignored. +static const SCEV *getExactSDiv(const SCEV *LHS, const SCEV *RHS, + ScalarEvolution &SE, + bool IgnoreSignificantBits = false) { // Handle the trivial case, which works for any SCEV type. if (LHS == RHS) return SE.getIntegerSCEV(1, LHS->getType()); @@ -528,39 +393,44 @@ static const SCEV *getSDiv(const SCEV *LHS, const SCEV *RHS, .sdiv(RC->getValue()->getValue())); } - // Distribute the sdiv over addrec operands. + // Distribute the sdiv over addrec operands, if the addrec doesn't overflow. if (const SCEVAddRecExpr *AR = dyn_cast(LHS)) { - const SCEV *Start = getSDiv(AR->getStart(), RHS, SE, - IgnoreSignificantBits); - if (!Start) return 0; - const SCEV *Step = getSDiv(AR->getStepRecurrence(SE), RHS, SE, - IgnoreSignificantBits); - if (!Step) return 0; - return SE.getAddRecExpr(Start, Step, AR->getLoop()); + if (IgnoreSignificantBits || isAddRecSExtable(AR, SE)) { + const SCEV *Start = getExactSDiv(AR->getStart(), RHS, SE, + IgnoreSignificantBits); + if (!Start) return 0; + const SCEV *Step = getExactSDiv(AR->getStepRecurrence(SE), RHS, SE, + IgnoreSignificantBits); + if (!Step) return 0; + return SE.getAddRecExpr(Start, Step, AR->getLoop()); + } } - // Distribute the sdiv over add operands. + // Distribute the sdiv over add operands, if the add doesn't overflow. if (const SCEVAddExpr *Add = dyn_cast(LHS)) { - SmallVector Ops; - for (SCEVAddExpr::op_iterator I = Add->op_begin(), E = Add->op_end(); - I != E; ++I) { - const SCEV *Op = getSDiv(*I, RHS, SE, - IgnoreSignificantBits); - if (!Op) return 0; - Ops.push_back(Op); + if (IgnoreSignificantBits || isAddSExtable(Add, SE)) { + SmallVector Ops; + for (SCEVAddExpr::op_iterator I = Add->op_begin(), E = Add->op_end(); + I != E; ++I) { + const SCEV *Op = getExactSDiv(*I, RHS, SE, + IgnoreSignificantBits); + if (!Op) return 0; + Ops.push_back(Op); + } + return SE.getAddExpr(Ops); } - return SE.getAddExpr(Ops); } // Check for a multiply operand that we can pull RHS out of. if (const SCEVMulExpr *Mul = dyn_cast(LHS)) - if (IgnoreSignificantBits || Mul->hasNoSignedWrap()) { + if (IgnoreSignificantBits || isMulSExtable(Mul, SE)) { SmallVector Ops; bool Found = false; for (SCEVMulExpr::op_iterator I = Mul->op_begin(), E = Mul->op_end(); I != E; ++I) { if (!Found) - if (const SCEV *Q = getSDiv(*I, RHS, SE, IgnoreSignificantBits)) { + if (const SCEV *Q = getExactSDiv(*I, RHS, SE, + IgnoreSignificantBits)) { Ops.push_back(Q); Found = true; continue; @@ -574,68 +444,6 @@ static const SCEV *getSDiv(const SCEV *LHS, const SCEV *RHS, return 0; } -namespace { - -/// LSRUse - This class holds the state that LSR keeps for each use in -/// IVUsers, as well as uses invented by LSR itself. It includes information -/// about what kinds of things can be folded into the user, information -/// about the user itself, and information about how the use may be satisfied. -/// TODO: Represent multiple users of the same expression in common? -class LSRUse { - SmallSet FormulaeUniquifier; - -public: - /// KindType - An enum for a kind of use, indicating what types of - /// scaled and immediate operands it might support. - enum KindType { - Basic, ///< A normal use, with no folding. - Special, ///< A special case of basic, allowing -1 scales. - Address, ///< An address use; folding according to TargetLowering - ICmpZero ///< An equality icmp with both operands folded into one. - // TODO: Add a generic icmp too? - }; - - KindType Kind; - const Type *AccessTy; - Instruction *UserInst; - Value *OperandValToReplace; - - /// PostIncLoop - If this user is to use the post-incremented value of an - /// induction variable, this variable is non-null and holds the loop - /// associated with the induction variable. - const Loop *PostIncLoop; - - /// Formulae - A list of ways to build a value that can satisfy this user. - /// After the list is populated, one of these is selected heuristically and - /// used to formulate a replacement for OperandValToReplace in UserInst. - SmallVector Formulae; - - LSRUse() : Kind(Basic), AccessTy(0), - UserInst(0), OperandValToReplace(0), PostIncLoop(0) {} - - void InsertInitialFormula(const SCEV *S, Loop *L, - ScalarEvolution &SE, DominatorTree &DT); - void InsertSupplementalFormula(const SCEV *S); - - bool InsertFormula(const Formula &F); - - void Rewrite(Loop *L, SCEVExpander &Rewriter, - SmallVectorImpl &DeadInsts, - ScalarEvolution &SE, DominatorTree &DT, - Pass *P) const; - - void print(raw_ostream &OS) const; - void dump() const; - -private: - Value *Expand(BasicBlock::iterator IP, - Loop *L, SCEVExpander &Rewriter, - SmallVectorImpl &DeadInsts, - ScalarEvolution &SE, DominatorTree &DT) const; -}; - -} - /// ExtractImmediate - If S involves the addition of a constant integer value, /// return that integer value, and mutate S to point to a new SCEV with that /// value excluded. @@ -682,401 +490,325 @@ static GlobalValue *ExtractSymbol(const SCEV *&S, ScalarEvolution &SE) { return 0; } -/// isLegalUse - Test whether the use described by AM is "legal", meaning -/// it can be completely folded into the user instruction at isel time. -/// This includes address-mode folding and special icmp tricks. -static bool isLegalUse(const TargetLowering::AddrMode &AM, - LSRUse::KindType Kind, const Type *AccessTy, - const TargetLowering *TLI) { - switch (Kind) { - case LSRUse::Address: - // If we have low-level target information, ask the target if it can - // completely fold this address. - if (TLI) return TLI->isLegalAddressingMode(AM, AccessTy); +/// isAddressUse - Returns true if the specified instruction is using the +/// specified value as an address. +static bool isAddressUse(Instruction *Inst, Value *OperandVal) { + bool isAddress = isa(Inst); + if (StoreInst *SI = dyn_cast(Inst)) { + if (SI->getOperand(1) == OperandVal) + isAddress = true; + } else if (IntrinsicInst *II = dyn_cast(Inst)) { + // Addressing modes can also be folded into prefetches and a variety + // of intrinsics. + switch (II->getIntrinsicID()) { + default: break; + case Intrinsic::prefetch: + case Intrinsic::x86_sse2_loadu_dq: + case Intrinsic::x86_sse2_loadu_pd: + case Intrinsic::x86_sse_loadu_ps: + case Intrinsic::x86_sse_storeu_ps: + case Intrinsic::x86_sse2_storeu_pd: + case Intrinsic::x86_sse2_storeu_dq: + case Intrinsic::x86_sse2_storel_dq: + if (II->getOperand(1) == OperandVal) + isAddress = true; + break; + } + } + return isAddress; +} - // Otherwise, just guess that reg+reg addressing is legal. - return !AM.BaseGV && AM.BaseOffs == 0 && AM.Scale <= 1; +/// getAccessType - Return the type of the memory being accessed. +static const Type *getAccessType(const Instruction *Inst) { + const Type *AccessTy = Inst->getType(); + if (const StoreInst *SI = dyn_cast(Inst)) + AccessTy = SI->getOperand(0)->getType(); + else if (const IntrinsicInst *II = dyn_cast(Inst)) { + // Addressing modes can also be folded into prefetches and a variety + // of intrinsics. + switch (II->getIntrinsicID()) { + default: break; + case Intrinsic::x86_sse_storeu_ps: + case Intrinsic::x86_sse2_storeu_pd: + case Intrinsic::x86_sse2_storeu_dq: + case Intrinsic::x86_sse2_storel_dq: + AccessTy = II->getOperand(1)->getType(); + break; + } + } - case LSRUse::ICmpZero: - // There's not even a target hook for querying whether it would be legal - // to fold a GV into an ICmp. - if (AM.BaseGV) - return false; + // All pointers have the same requirements, so canonicalize them to an + // arbitrary pointer type to minimize variation. + if (const PointerType *PTy = dyn_cast(AccessTy)) + AccessTy = PointerType::get(IntegerType::get(PTy->getContext(), 1), + PTy->getAddressSpace()); - // ICmp only has two operands; don't allow more than two non-trivial parts. - if (AM.Scale != 0 && AM.HasBaseReg && AM.BaseOffs != 0) - return false; + return AccessTy; +} - // ICmp only supports no scale or a -1 scale, as we can "fold" a -1 scale - // by putting the scaled register in the other operand of the icmp. - if (AM.Scale != 0 && AM.Scale != -1) - return false; +/// DeleteTriviallyDeadInstructions - If any of the instructions is the +/// specified set are trivially dead, delete them and see if this makes any of +/// their operands subsequently dead. +static bool +DeleteTriviallyDeadInstructions(SmallVectorImpl &DeadInsts) { + bool Changed = false; - // If we have low-level target information, ask the target if it can - // fold an integer immediate on an icmp. - if (AM.BaseOffs != 0) { - if (TLI) return TLI->isLegalICmpImmediate(-AM.BaseOffs); - return false; - } + while (!DeadInsts.empty()) { + Instruction *I = dyn_cast_or_null(DeadInsts.pop_back_val()); - return true; + if (I == 0 || !isInstructionTriviallyDead(I)) + continue; - case LSRUse::Basic: - // Only handle single-register values. - return !AM.BaseGV && AM.Scale == 0 && AM.BaseOffs == 0; + for (User::op_iterator OI = I->op_begin(), E = I->op_end(); OI != E; ++OI) + if (Instruction *U = dyn_cast(*OI)) { + *OI = 0; + if (U->use_empty()) + DeadInsts.push_back(U); + } - case LSRUse::Special: - // Only handle -1 scales, or no scale. - return AM.Scale == 0 || AM.Scale == -1; + I->eraseFromParent(); + Changed = true; } - return false; + return Changed; } -static bool isAlwaysFoldable(const SCEV *S, - bool HasBaseReg, - LSRUse::KindType Kind, const Type *AccessTy, - const TargetLowering *TLI, - ScalarEvolution &SE) { - // Fast-path: zero is always foldable. - if (S->isZero()) return true; +namespace { - // Conservatively, create an address with an immediate and a - // base and a scale. - TargetLowering::AddrMode AM; - AM.BaseOffs = ExtractImmediate(S, SE); - AM.BaseGV = ExtractSymbol(S, SE); - AM.HasBaseReg = HasBaseReg; - AM.Scale = Kind == LSRUse::ICmpZero ? -1 : 1; +/// Cost - This class is used to measure and compare candidate formulae. +class Cost { + /// TODO: Some of these could be merged. Also, a lexical ordering + /// isn't always optimal. + unsigned NumRegs; + unsigned AddRecCost; + unsigned NumIVMuls; + unsigned NumBaseAdds; + unsigned ImmCost; + unsigned SetupCost; - // If there's anything else involved, it's not foldable. - if (!S->isZero()) return false; +public: + Cost() + : NumRegs(0), AddRecCost(0), NumIVMuls(0), NumBaseAdds(0), ImmCost(0), + SetupCost(0) {} - return isLegalUse(AM, Kind, AccessTy, TLI); -} + unsigned getNumRegs() const { return NumRegs; } -/// InsertFormula - If the given formula has not yet been inserted, add it -/// to the list, and return true. Return false otherwise. -bool LSRUse::InsertFormula(const Formula &F) { - Formula Copy = F; + bool operator<(const Cost &Other) const; - // Sort the base regs, to avoid adding the same solution twice with - // the base regs in different orders. This uses host pointer values, but - // it doesn't matter since it's only used for uniquifying. - std::sort(Copy.BaseRegs.begin(), Copy.BaseRegs.end()); + void Loose(); - DEBUG(for (SmallVectorImpl::const_iterator I = - F.BaseRegs.begin(), E = F.BaseRegs.end(); I != E; ++I) - assert(!(*I)->isZero() && "Zero allocated in a base register!"); - assert((!F.ScaledReg || !F.ScaledReg->isZero()) && - "Zero allocated in a scaled register!")); + void RateFormula(const Formula &F, + SmallPtrSet &Regs, + const DenseSet &VisitedRegs, + const Loop *L, + const SmallVectorImpl &Offsets, + ScalarEvolution &SE, DominatorTree &DT); - if (FormulaeUniquifier.insert(Copy)) { - Formulae.push_back(F); - return true; - } + void print(raw_ostream &OS) const; + void dump() const; - return false; -} +private: + void RateRegister(const SCEV *Reg, + SmallPtrSet &Regs, + const Loop *L, + ScalarEvolution &SE, DominatorTree &DT); + void RatePrimaryRegister(const SCEV *Reg, + SmallPtrSet &Regs, + const Loop *L, + ScalarEvolution &SE, DominatorTree &DT); +}; -void -LSRUse::InsertInitialFormula(const SCEV *S, Loop *L, - ScalarEvolution &SE, DominatorTree &DT) { - Formula F; - F.InitialMatch(S, L, SE, DT); - bool Inserted = InsertFormula(F); - assert(Inserted && "Initial formula already exists!"); (void)Inserted; } -void -LSRUse::InsertSupplementalFormula(const SCEV *S) { - Formula F; - F.BaseRegs.push_back(S); - F.AM.HasBaseReg = true; - bool Inserted = InsertFormula(F); - assert(Inserted && "Supplemental formula already exists!"); (void)Inserted; -} +/// RateRegister - Tally up interesting quantities from the given register. +void Cost::RateRegister(const SCEV *Reg, + SmallPtrSet &Regs, + const Loop *L, + ScalarEvolution &SE, DominatorTree &DT) { + if (const SCEVAddRecExpr *AR = dyn_cast(Reg)) { + if (AR->getLoop() == L) + AddRecCost += 1; /// TODO: This should be a function of the stride. + + // If this is an addrec for a loop that's already been visited by LSR, + // don't second-guess its addrec phi nodes. LSR isn't currently smart + // enough to reason about more than one loop at a time. Consider these + // registers free and leave them alone. + else if (L->contains(AR->getLoop()) || + (!AR->getLoop()->contains(L) && + DT.dominates(L->getHeader(), AR->getLoop()->getHeader()))) { + for (BasicBlock::iterator I = AR->getLoop()->getHeader()->begin(); + PHINode *PN = dyn_cast(I); ++I) + if (SE.isSCEVable(PN->getType()) && + (SE.getEffectiveSCEVType(PN->getType()) == + SE.getEffectiveSCEVType(AR->getType())) && + SE.getSCEV(PN) == AR) + return; + + // If this isn't one of the addrecs that the loop already has, it + // would require a costly new phi and add. TODO: This isn't + // precisely modeled right now. + ++NumBaseAdds; + if (!Regs.count(AR->getStart())) + RateRegister(AR->getStart(), Regs, L, SE, DT); + } -/// getImmediateDominator - A handy utility for the specific DominatorTree -/// query that we need here. -/// -static BasicBlock *getImmediateDominator(BasicBlock *BB, DominatorTree &DT) { - DomTreeNode *Node = DT.getNode(BB); - if (!Node) return 0; - Node = Node->getIDom(); - if (!Node) return 0; - return Node->getBlock(); + // Add the step value register, if it needs one. + // TODO: The non-affine case isn't precisely modeled here. + if (!AR->isAffine() || !isa(AR->getOperand(1))) + if (!Regs.count(AR->getStart())) + RateRegister(AR->getOperand(1), Regs, L, SE, DT); + } + ++NumRegs; + + // Rough heuristic; favor registers which don't require extra setup + // instructions in the preheader. + if (!isa(Reg) && + !isa(Reg) && + !(isa(Reg) && + (isa(cast(Reg)->getStart()) || + isa(cast(Reg)->getStart())))) + ++SetupCost; +} + +/// RatePrimaryRegister - Record this register in the set. If we haven't seen it +/// before, rate it. +void Cost::RatePrimaryRegister(const SCEV *Reg, + SmallPtrSet &Regs, + const Loop *L, + ScalarEvolution &SE, DominatorTree &DT) { + if (Regs.insert(Reg)) + RateRegister(Reg, Regs, L, SE, DT); } -Value *LSRUse::Expand(BasicBlock::iterator IP, - Loop *L, SCEVExpander &Rewriter, - SmallVectorImpl &DeadInsts, - ScalarEvolution &SE, DominatorTree &DT) const { - // Then, collect some instructions which we will remain dominated by when - // expanding the replacement. These must be dominated by any operands that - // will be required in the expansion. - SmallVector Inputs; - if (Instruction *I = dyn_cast(OperandValToReplace)) - Inputs.push_back(I); - if (Kind == ICmpZero) - if (Instruction *I = - dyn_cast(cast(UserInst)->getOperand(1))) - Inputs.push_back(I); - if (PostIncLoop && !L->contains(UserInst)) - Inputs.push_back(L->getLoopLatch()->getTerminator()); - - // Then, climb up the immediate dominator tree as far as we can go while - // still being dominated by the input positions. - for (;;) { - bool AllDominate = true; - Instruction *BetterPos = 0; - BasicBlock *IDom = getImmediateDominator(IP->getParent(), DT); - if (!IDom) break; - Instruction *Tentative = IDom->getTerminator(); - for (SmallVectorImpl::const_iterator I = Inputs.begin(), - E = Inputs.end(); I != E; ++I) { - Instruction *Inst = *I; - if (Inst == Tentative || !DT.dominates(Inst, Tentative)) { - AllDominate = false; - break; - } - if (IDom == Inst->getParent() && - (!BetterPos || DT.dominates(BetterPos, Inst))) - BetterPos = next(BasicBlock::iterator(Inst)); +void Cost::RateFormula(const Formula &F, + SmallPtrSet &Regs, + const DenseSet &VisitedRegs, + const Loop *L, + const SmallVectorImpl &Offsets, + ScalarEvolution &SE, DominatorTree &DT) { + // Tally up the registers. + if (const SCEV *ScaledReg = F.ScaledReg) { + if (VisitedRegs.count(ScaledReg)) { + Loose(); + return; } - if (!AllDominate) - break; - if (BetterPos) - IP = BetterPos; - else - IP = Tentative; + RatePrimaryRegister(ScaledReg, Regs, L, SE, DT); } - while (isa(IP)) ++IP; - - // The first formula in the list is the winner. - const Formula &F = Formulae.front(); - - // Inform the Rewriter if we have a post-increment use, so that it can - // perform an advantageous expansion. - Rewriter.setPostInc(PostIncLoop); - - // This is the type that the user actually needs. - const Type *OpTy = OperandValToReplace->getType(); - // This will be the type that we'll initially expand to. - const Type *Ty = F.getType(); - if (!Ty) - // No type known; just expand directly to the ultimate type. - Ty = OpTy; - else if (SE.getEffectiveSCEVType(Ty) == SE.getEffectiveSCEVType(OpTy)) - // Expand directly to the ultimate type if it's the right size. - Ty = OpTy; - // This is the type to do integer arithmetic in. - const Type *IntTy = SE.getEffectiveSCEVType(Ty); - - // Build up a list of operands to add together to form the full base. - SmallVector Ops; - - // Expand the BaseRegs portion. for (SmallVectorImpl::const_iterator I = F.BaseRegs.begin(), E = F.BaseRegs.end(); I != E; ++I) { - const SCEV *Reg = *I; - assert(!Reg->isZero() && "Zero allocated in a base register!"); - - // If we're expanding for a post-inc user for the add-rec's loop, make the - // post-inc adjustment. - if (const SCEVAddRecExpr *AR = dyn_cast(Reg)) - if (AR->getLoop() == PostIncLoop) - Reg = SE.getAddExpr(Reg, AR->getStepRecurrence(SE)); + const SCEV *BaseReg = *I; + if (VisitedRegs.count(BaseReg)) { + Loose(); + return; + } + RatePrimaryRegister(BaseReg, Regs, L, SE, DT); - Ops.push_back(SE.getUnknown(Rewriter.expandCodeFor(Reg, 0, IP))); + NumIVMuls += isa(BaseReg) && + BaseReg->hasComputableLoopEvolution(L); } - // Expand the ScaledReg portion. - Value *ICmpScaledV = 0; - if (F.AM.Scale != 0) { - const SCEV *ScaledS = F.ScaledReg; - - // If we're expanding for a post-inc user for the add-rec's loop, make the - // post-inc adjustment. - if (const SCEVAddRecExpr *AR = dyn_cast(ScaledS)) - if (AR->getLoop() == PostIncLoop) - ScaledS = SE.getAddExpr(ScaledS, AR->getStepRecurrence(SE)); + if (F.BaseRegs.size() > 1) + NumBaseAdds += F.BaseRegs.size() - 1; - if (Kind == ICmpZero) { - // An interesting way of "folding" with an icmp is to use a negated - // scale, which we'll implement by inserting it into the other operand - // of the icmp. - assert(F.AM.Scale == -1 && - "The only scale supported by ICmpZero uses is -1!"); - ICmpScaledV = Rewriter.expandCodeFor(ScaledS, 0, IP); - } else { - // Otherwise just expand the scaled register and an explicit scale, - // which is expected to be matched as part of the address. - ScaledS = SE.getUnknown(Rewriter.expandCodeFor(ScaledS, 0, IP)); - const Type *ScaledTy = SE.getEffectiveSCEVType(ScaledS->getType()); - ScaledS = SE.getMulExpr(ScaledS, - SE.getSCEV(ConstantInt::get(ScaledTy, - F.AM.Scale))); - Ops.push_back(ScaledS); - } + // Tally up the non-zero immediates. + for (SmallVectorImpl::const_iterator I = Offsets.begin(), + E = Offsets.end(); I != E; ++I) { + int64_t Offset = (uint64_t)*I + F.AM.BaseOffs; + if (F.AM.BaseGV) + ImmCost += 64; // Handle symbolic values conservatively. + // TODO: This should probably be the pointer size. + else if (Offset != 0) + ImmCost += APInt(64, Offset, true).getMinSignedBits(); } +} - // Expand the immediate portions. - if (F.AM.BaseGV) - Ops.push_back(SE.getSCEV(F.AM.BaseGV)); - if (F.AM.BaseOffs != 0) { - if (Kind == ICmpZero) { - // The other interesting way of "folding" with an ICmpZero is to use a - // negated immediate. - if (!ICmpScaledV) - ICmpScaledV = ConstantInt::get(IntTy, -F.AM.BaseOffs); - else { - Ops.push_back(SE.getUnknown(ICmpScaledV)); - ICmpScaledV = ConstantInt::get(IntTy, F.AM.BaseOffs); - } - } else { - // Just add the immediate values. These again are expected to be matched - // as part of the address. - Ops.push_back(SE.getSCEV(ConstantInt::get(IntTy, F.AM.BaseOffs))); - } - } +/// Loose - Set this cost to a loosing value. +void Cost::Loose() { + NumRegs = ~0u; + AddRecCost = ~0u; + NumIVMuls = ~0u; + NumBaseAdds = ~0u; + ImmCost = ~0u; + SetupCost = ~0u; +} - // Emit instructions summing all the operands. - const SCEV *FullS = Ops.empty() ? - SE.getIntegerSCEV(0, IntTy) : - SE.getAddExpr(Ops); - Value *FullV = Rewriter.expandCodeFor(FullS, Ty, IP); +/// operator< - Choose the lower cost. +bool Cost::operator<(const Cost &Other) const { + if (NumRegs != Other.NumRegs) + return NumRegs < Other.NumRegs; + if (AddRecCost != Other.AddRecCost) + return AddRecCost < Other.AddRecCost; + if (NumIVMuls != Other.NumIVMuls) + return NumIVMuls < Other.NumIVMuls; + if (NumBaseAdds != Other.NumBaseAdds) + return NumBaseAdds < Other.NumBaseAdds; + if (ImmCost != Other.ImmCost) + return ImmCost < Other.ImmCost; + if (SetupCost != Other.SetupCost) + return SetupCost < Other.SetupCost; + return false; +} - // We're done expanding now, so reset the rewriter. - Rewriter.setPostInc(0); +void Cost::print(raw_ostream &OS) const { + OS << NumRegs << " reg" << (NumRegs == 1 ? "" : "s"); + if (AddRecCost != 0) + OS << ", with addrec cost " << AddRecCost; + if (NumIVMuls != 0) + OS << ", plus " << NumIVMuls << " IV mul" << (NumIVMuls == 1 ? "" : "s"); + if (NumBaseAdds != 0) + OS << ", plus " << NumBaseAdds << " base add" + << (NumBaseAdds == 1 ? "" : "s"); + if (ImmCost != 0) + OS << ", plus " << ImmCost << " imm cost"; + if (SetupCost != 0) + OS << ", plus " << SetupCost << " setup cost"; +} - // An ICmpZero Formula represents an ICmp which we're handling as a - // comparison against zero. Now that we've expanded an expression for that - // form, update the ICmp's other operand. - if (Kind == ICmpZero) { - ICmpInst *CI = cast(UserInst); - DeadInsts.push_back(CI->getOperand(1)); - assert(!F.AM.BaseGV && "ICmp does not support folding a global value and " - "a scale at the same time!"); - if (F.AM.Scale == -1) { - if (ICmpScaledV->getType() != OpTy) { - Instruction *Cast = - CastInst::Create(CastInst::getCastOpcode(ICmpScaledV, false, - OpTy, false), - ICmpScaledV, OpTy, "tmp", CI); - ICmpScaledV = Cast; - } - CI->setOperand(1, ICmpScaledV); - } else { - assert(F.AM.Scale == 0 && - "ICmp does not support folding a global value and " - "a scale at the same time!"); - Constant *C = ConstantInt::getSigned(SE.getEffectiveSCEVType(OpTy), - -(uint64_t)F.AM.BaseOffs); - if (C->getType() != OpTy) - C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, - OpTy, false), - C, OpTy); +void Cost::dump() const { + print(errs()); errs() << '\n'; +} - CI->setOperand(1, C); - } - } +namespace { - return FullV; -} +/// LSRFixup - An operand value in an instruction which is to be replaced +/// with some equivalent, possibly strength-reduced, replacement. +struct LSRFixup { + /// UserInst - The instruction which will be updated. + Instruction *UserInst; -/// Rewrite - Emit instructions for the leading candidate expression for this -/// LSRUse (this is called "expanding"), and update the UserInst to reference -/// the newly expanded value. -void LSRUse::Rewrite(Loop *L, SCEVExpander &Rewriter, - SmallVectorImpl &DeadInsts, - ScalarEvolution &SE, DominatorTree &DT, - Pass *P) const { - const Type *OpTy = OperandValToReplace->getType(); + /// OperandValToReplace - The operand of the instruction which will + /// be replaced. The operand may be used more than once; every instance + /// will be replaced. + Value *OperandValToReplace; - // First, find an insertion point that dominates UserInst. For PHI nodes, - // find the nearest block which dominates all the relevant uses. - if (PHINode *PN = dyn_cast(UserInst)) { - DenseMap Inserted; - for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) - if (PN->getIncomingValue(i) == OperandValToReplace) { - BasicBlock *BB = PN->getIncomingBlock(i); - - // If this is a critical edge, split the edge so that we do not insert - // the code on all predecessor/successor paths. We do this unless this - // is the canonical backedge for this loop, which complicates post-inc - // users. - if (e != 1 && BB->getTerminator()->getNumSuccessors() > 1 && - !isa(BB->getTerminator()) && - (PN->getParent() != L->getHeader() || !L->contains(BB))) { - // Split the critical edge. - BasicBlock *NewBB = SplitCriticalEdge(BB, PN->getParent(), P); - - // If PN is outside of the loop and BB is in the loop, we want to - // move the block to be immediately before the PHI block, not - // immediately after BB. - if (L->contains(BB) && !L->contains(PN)) - NewBB->moveBefore(PN->getParent()); - - // Splitting the edge can reduce the number of PHI entries we have. - e = PN->getNumIncomingValues(); - BB = NewBB; - i = PN->getBasicBlockIndex(BB); - } + /// PostIncLoop - If this user is to use the post-incremented value of an + /// induction variable, this variable is non-null and holds the loop + /// associated with the induction variable. + const Loop *PostIncLoop; - std::pair::iterator, bool> Pair = - Inserted.insert(std::make_pair(BB, static_cast(0))); - if (!Pair.second) - PN->setIncomingValue(i, Pair.first->second); - else { - Value *FullV = Expand(BB->getTerminator(), - L, Rewriter, DeadInsts, SE, DT); - - // If this is reuse-by-noop-cast, insert the noop cast. - if (FullV->getType() != OpTy) - FullV = - CastInst::Create(CastInst::getCastOpcode(FullV, false, - OpTy, false), - FullV, OperandValToReplace->getType(), - "tmp", BB->getTerminator()); - - PN->setIncomingValue(i, FullV); - Pair.first->second = FullV; - } - } - } else { - Value *FullV = Expand(UserInst, L, Rewriter, DeadInsts, SE, DT); + /// LUIdx - The index of the LSRUse describing the expression which + /// this fixup needs, minus an offset (below). + size_t LUIdx; - // If this is reuse-by-noop-cast, insert the noop cast. - if (FullV->getType() != OpTy) { - Instruction *Cast = - CastInst::Create(CastInst::getCastOpcode(FullV, false, OpTy, false), - FullV, OpTy, "tmp", UserInst); - FullV = Cast; - } + /// Offset - A constant offset to be added to the LSRUse expression. + /// This allows multiple fixups to share the same LSRUse with different + /// offsets, for example in an unrolled loop. + int64_t Offset; - // Update the user. - UserInst->replaceUsesOfWith(OperandValToReplace, FullV); - } + LSRFixup(); + + void print(raw_ostream &OS) const; + void dump() const; +}; - DeadInsts.push_back(OperandValToReplace); } -void LSRUse::print(raw_ostream &OS) const { - OS << "LSR Use: Kind="; - switch (Kind) { - case Basic: OS << "Basic"; break; - case Special: OS << "Special"; break; - case ICmpZero: OS << "ICmpZero"; break; - case Address: - OS << "Address of "; - if (isa(AccessTy)) - OS << "pointer"; // the full pointer type could be really verbose - else - OS << *AccessTy; - } +LSRFixup::LSRFixup() + : UserInst(0), OperandValToReplace(0), PostIncLoop(0), + LUIdx(~size_t(0)), Offset(0) {} - OS << ", UserInst="; +void LSRFixup::print(raw_ostream &OS) const { + OS << "UserInst="; // Store is common and interesting enough to be worth special-casing. if (StoreInst *Store = dyn_cast(UserInst)) { OS << "store "; @@ -1093,286 +825,312 @@ void LSRUse::print(raw_ostream &OS) const { OS << ", PostIncLoop="; WriteAsOperand(OS, PostIncLoop->getHeader(), /*PrintType=*/false); } + + if (LUIdx != ~size_t(0)) + OS << ", LUIdx=" << LUIdx; + + if (Offset != 0) + OS << ", Offset=" << Offset; } -void LSRUse::dump() const { +void LSRFixup::dump() const { print(errs()); errs() << '\n'; } namespace { -/// Score - This class is used to measure and compare candidate formulae. -class Score { - unsigned NumRegs; - unsigned NumPhis; - unsigned NumIVMuls; - unsigned NumBaseAdds; - unsigned NumImms; +/// UniquifierDenseMapInfo - A DenseMapInfo implementation for holding +/// DenseMaps and DenseSets of sorted SmallVectors of const SCEV*. +struct UniquifierDenseMapInfo { + static SmallVector getEmptyKey() { + SmallVector V; + V.push_back(reinterpret_cast(-1)); + return V; + } + + static SmallVector getTombstoneKey() { + SmallVector V; + V.push_back(reinterpret_cast(-2)); + return V; + } + + static unsigned getHashValue(const SmallVector &V) { + unsigned Result = 0; + for (SmallVectorImpl::const_iterator I = V.begin(), + E = V.end(); I != E; ++I) + Result ^= DenseMapInfo::getHashValue(*I); + return Result; + } + + static bool isEqual(const SmallVector &LHS, + const SmallVector &RHS) { + return LHS == RHS; + } +}; + +/// LSRUse - This class holds the state that LSR keeps for each use in +/// IVUsers, as well as uses invented by LSR itself. It includes information +/// about what kinds of things can be folded into the user, information about +/// the user itself, and information about how the use may be satisfied. +/// TODO: Represent multiple users of the same expression in common? +class LSRUse { + DenseSet, UniquifierDenseMapInfo> Uniquifier; public: - Score() - : NumRegs(0), NumPhis(0), NumIVMuls(0), NumBaseAdds(0), NumImms(0) {} + /// KindType - An enum for a kind of use, indicating what types of + /// scaled and immediate operands it might support. + enum KindType { + Basic, ///< A normal use, with no folding. + Special, ///< A special case of basic, allowing -1 scales. + Address, ///< An address use; folding according to TargetLowering + ICmpZero ///< An equality icmp with both operands folded into one. + // TODO: Add a generic icmp too? + }; + + KindType Kind; + const Type *AccessTy; - void RateInitial(SmallVector const &Uses, const Loop *L, - ScalarEvolution &SE); + SmallVector Offsets; + int64_t MinOffset; + int64_t MaxOffset; - void Rate(const SCEV *Reg, const SmallBitVector &Bits, - const SmallVector &Uses, const Loop *L, - ScalarEvolution &SE); + /// AllFixupsOutsideLoop - This records whether all of the fixups using this + /// LSRUse are outside of the loop, in which case some special-case heuristics + /// may be used. + bool AllFixupsOutsideLoop; - unsigned getNumRegs() const { return NumRegs; } + /// Formulae - A list of ways to build a value that can satisfy this user. + /// After the list is populated, one of these is selected heuristically and + /// used to formulate a replacement for OperandValToReplace in UserInst. + SmallVector Formulae; + + /// Regs - The set of register candidates used by all formulae in this LSRUse. + SmallPtrSet Regs; + + LSRUse(KindType K, const Type *T) : Kind(K), AccessTy(T), + MinOffset(INT64_MAX), + MaxOffset(INT64_MIN), + AllFixupsOutsideLoop(true) {} - bool operator<(const Score &Other) const; + bool InsertFormula(const Formula &F); - void print_details(raw_ostream &OS, const SCEV *Reg, - const SmallPtrSet &Regs) const; + void check() const; void print(raw_ostream &OS) const; void dump() const; +}; -private: - void RateRegister(const SCEV *Reg, SmallPtrSet &Regs, - const Loop *L); - void RateFormula(const Formula &F, SmallPtrSet &Regs, - const Loop *L); +/// InsertFormula - If the given formula has not yet been inserted, add it to +/// the list, and return true. Return false otherwise. +bool LSRUse::InsertFormula(const Formula &F) { + SmallVector Key = F.BaseRegs; + if (F.ScaledReg) Key.push_back(F.ScaledReg); + // Unstable sort by host order ok, because this is only used for uniquifying. + std::sort(Key.begin(), Key.end()); - void Loose(); -}; + if (!Uniquifier.insert(Key).second) + return false; -} + // Using a register to hold the value of 0 is not profitable. + assert((!F.ScaledReg || !F.ScaledReg->isZero()) && + "Zero allocated in a scaled register!"); +#ifndef NDEBUG + for (SmallVectorImpl::const_iterator I = + F.BaseRegs.begin(), E = F.BaseRegs.end(); I != E; ++I) + assert(!(*I)->isZero() && "Zero allocated in a base register!"); +#endif -/// RateRegister - Tally up interesting quantities from the given register. -void Score::RateRegister(const SCEV *Reg, - SmallPtrSet &Regs, - const Loop *L) { - if (Regs.insert(Reg)) - if (const SCEVAddRecExpr *AR = dyn_cast(Reg)) { - NumPhis += AR->getLoop() == L; + // Add the formula to the list. + Formulae.push_back(F); - // Add the step value register, if it needs one. - if (!AR->isAffine() || !isa(AR->getOperand(1))) - RateRegister(AR->getOperand(1), Regs, L); - } -} + // Record registers now being used by this use. + if (F.ScaledReg) Regs.insert(F.ScaledReg); + Regs.insert(F.BaseRegs.begin(), F.BaseRegs.end()); -void Score::RateFormula(const Formula &F, - SmallPtrSet &Regs, - const Loop *L) { - // Tally up the registers. - if (F.ScaledReg) - RateRegister(F.ScaledReg, Regs, L); - for (SmallVectorImpl::const_iterator I = F.BaseRegs.begin(), - E = F.BaseRegs.end(); I != E; ++I) { - const SCEV *BaseReg = *I; - RateRegister(BaseReg, Regs, L); + return true; +} - NumIVMuls += isa(BaseReg) && - BaseReg->hasComputableLoopEvolution(L); +void LSRUse::print(raw_ostream &OS) const { + OS << "LSR Use: Kind="; + switch (Kind) { + case Basic: OS << "Basic"; break; + case Special: OS << "Special"; break; + case ICmpZero: OS << "ICmpZero"; break; + case Address: + OS << "Address of "; + if (AccessTy->isPointerTy()) + OS << "pointer"; // the full pointer type could be really verbose + else + OS << *AccessTy; } - if (F.BaseRegs.size() > 1) - NumBaseAdds += F.BaseRegs.size() - 1; + OS << ", Offsets={"; + for (SmallVectorImpl::const_iterator I = Offsets.begin(), + E = Offsets.end(); I != E; ++I) { + OS << *I; + if (next(I) != E) + OS << ','; + } + OS << '}'; - // Tally up the non-zero immediates. - if (F.AM.BaseGV || F.AM.BaseOffs != 0) - ++NumImms; + if (AllFixupsOutsideLoop) + OS << ", all-fixups-outside-loop"; } -/// Loose - Set this score to a loosing value. -void Score::Loose() { - NumRegs = ~0u; - NumPhis = ~0u; - NumIVMuls = ~0u; - NumBaseAdds = ~0u; - NumImms = ~0u; +void LSRUse::dump() const { + print(errs()); errs() << '\n'; } -/// RateInitial - Compute a score for the initial "fully reduced" solution. -void Score::RateInitial(SmallVector const &Uses, const Loop *L, - ScalarEvolution &SE) { - SmallPtrSet Regs; - for (SmallVectorImpl::const_iterator I = Uses.begin(), - E = Uses.end(); I != E; ++I) - RateFormula(I->Formulae.front(), Regs, L); - NumRegs += Regs.size(); - - DEBUG(print_details(dbgs(), 0, Regs)); -} - -/// Rate - Compute a score for the solution where the reuse associated with -/// putting Reg in a register is selected. -void Score::Rate(const SCEV *Reg, const SmallBitVector &Bits, - const SmallVector &Uses, const Loop *L, - ScalarEvolution &SE) { - SmallPtrSet Regs; - for (size_t i = 0, e = Uses.size(); i != e; ++i) { - const LSRUse &LU = Uses[i]; - - const Formula *BestFormula = 0; - if (i >= Bits.size() || !Bits.test(i)) - // This use doesn't use the current register. Just go with the current - // leading candidate formula. - BestFormula = &LU.Formulae.front(); - else - // Find the best formula for this use that uses the current register. - for (SmallVectorImpl::const_iterator I = LU.Formulae.begin(), - E = LU.Formulae.end(); I != E; ++I) { - const Formula &F = *I; - if (F.referencesReg(Reg) && - (!BestFormula || ComplexitySorter()(F, *BestFormula))) - BestFormula = &F; - } +/// isLegalUse - Test whether the use described by AM is "legal", meaning it can +/// be completely folded into the user instruction at isel time. This includes +/// address-mode folding and special icmp tricks. +static bool isLegalUse(const TargetLowering::AddrMode &AM, + LSRUse::KindType Kind, const Type *AccessTy, + const TargetLowering *TLI) { + switch (Kind) { + case LSRUse::Address: + // If we have low-level target information, ask the target if it can + // completely fold this address. + if (TLI) return TLI->isLegalAddressingMode(AM, AccessTy); - // If we didn't find *any* forumlae, because earlier we eliminated some - // in greedy fashion, skip the current register's reuse opportunity. - if (!BestFormula) { - DEBUG(dbgs() << "Reuse with reg " << *Reg - << " wouldn't help any users.\n"); - Loose(); - return; - } + // Otherwise, just guess that reg+reg addressing is legal. + return !AM.BaseGV && AM.BaseOffs == 0 && AM.Scale <= 1; - // For an in-loop post-inc user, don't allow multiple base registers, - // because that would require an awkward in-loop add after the increment. - if (LU.PostIncLoop && LU.PostIncLoop->contains(LU.UserInst) && - BestFormula->BaseRegs.size() > 1) { - DEBUG(dbgs() << "Reuse with reg " << *Reg - << " would require an in-loop post-inc add: "; - BestFormula->dump()); - Loose(); - return; - } + case LSRUse::ICmpZero: + // There's not even a target hook for querying whether it would be legal to + // fold a GV into an ICmp. + if (AM.BaseGV) + return false; - RateFormula(*BestFormula, Regs, L); - } - NumRegs += Regs.size(); + // ICmp only has two operands; don't allow more than two non-trivial parts. + if (AM.Scale != 0 && AM.HasBaseReg && AM.BaseOffs != 0) + return false; - DEBUG(print_details(dbgs(), Reg, Regs)); -} + // ICmp only supports no scale or a -1 scale, as we can "fold" a -1 scale by + // putting the scaled register in the other operand of the icmp. + if (AM.Scale != 0 && AM.Scale != -1) + return false; -/// operator< - Choose the better score. -bool Score::operator<(const Score &Other) const { - if (NumRegs != Other.NumRegs) - return NumRegs < Other.NumRegs; - if (NumPhis != Other.NumPhis) - return NumPhis < Other.NumPhis; - if (NumIVMuls != Other.NumIVMuls) - return NumIVMuls < Other.NumIVMuls; - if (NumBaseAdds != Other.NumBaseAdds) - return NumBaseAdds < Other.NumBaseAdds; - return NumImms < Other.NumImms; -} - -void Score::print_details(raw_ostream &OS, - const SCEV *Reg, - const SmallPtrSet &Regs) const { - if (Reg) OS << "Reuse with reg " << *Reg << " would require "; - else OS << "The initial solution would require "; - print(OS); - OS << ". Regs:"; - for (SmallPtrSet::const_iterator I = Regs.begin(), - E = Regs.end(); I != E; ++I) - OS << ' ' << **I; - OS << '\n'; -} + // If we have low-level target information, ask the target if it can fold an + // integer immediate on an icmp. + if (AM.BaseOffs != 0) { + if (TLI) return TLI->isLegalICmpImmediate(-AM.BaseOffs); + return false; + } -void Score::print(raw_ostream &OS) const { - OS << NumRegs << " reg" << (NumRegs == 1 ? "" : "s"); - if (NumPhis != 0) - OS << ", including " << NumPhis << " PHI" << (NumPhis == 1 ? "" : "s"); - if (NumIVMuls != 0) - OS << ", plus " << NumIVMuls << " IV mul" << (NumIVMuls == 1 ? "" : "s"); - if (NumBaseAdds != 0) - OS << ", plus " << NumBaseAdds << " base add" - << (NumBaseAdds == 1 ? "" : "s"); - if (NumImms != 0) - OS << ", plus " << NumImms << " imm" << (NumImms == 1 ? "" : "s"); -} + return true; -void Score::dump() const { - print(errs()); errs() << '\n'; -} + case LSRUse::Basic: + // Only handle single-register values. + return !AM.BaseGV && AM.Scale == 0 && AM.BaseOffs == 0; -/// isAddressUse - Returns true if the specified instruction is using the -/// specified value as an address. -static bool isAddressUse(Instruction *Inst, Value *OperandVal) { - bool isAddress = isa(Inst); - if (StoreInst *SI = dyn_cast(Inst)) { - if (SI->getOperand(1) == OperandVal) - isAddress = true; - } else if (IntrinsicInst *II = dyn_cast(Inst)) { - // Addressing modes can also be folded into prefetches and a variety - // of intrinsics. - switch (II->getIntrinsicID()) { - default: break; - case Intrinsic::prefetch: - case Intrinsic::x86_sse2_loadu_dq: - case Intrinsic::x86_sse2_loadu_pd: - case Intrinsic::x86_sse_loadu_ps: - case Intrinsic::x86_sse_storeu_ps: - case Intrinsic::x86_sse2_storeu_pd: - case Intrinsic::x86_sse2_storeu_dq: - case Intrinsic::x86_sse2_storel_dq: - if (II->getOperand(1) == OperandVal) - isAddress = true; - break; - } + case LSRUse::Special: + // Only handle -1 scales, or no scale. + return AM.Scale == 0 || AM.Scale == -1; } - return isAddress; + + return false; } -/// getAccessType - Return the type of the memory being accessed. -static const Type *getAccessType(const Instruction *Inst) { - const Type *AccessTy = Inst->getType(); - if (const StoreInst *SI = dyn_cast(Inst)) - AccessTy = SI->getOperand(0)->getType(); - else if (const IntrinsicInst *II = dyn_cast(Inst)) { - // Addressing modes can also be folded into prefetches and a variety - // of intrinsics. - switch (II->getIntrinsicID()) { - default: break; - case Intrinsic::x86_sse_storeu_ps: - case Intrinsic::x86_sse2_storeu_pd: - case Intrinsic::x86_sse2_storeu_dq: - case Intrinsic::x86_sse2_storel_dq: - AccessTy = II->getOperand(1)->getType(); - break; - } +static bool isLegalUse(TargetLowering::AddrMode AM, + int64_t MinOffset, int64_t MaxOffset, + LSRUse::KindType Kind, const Type *AccessTy, + const TargetLowering *TLI) { + // Check for overflow. + if (((int64_t)((uint64_t)AM.BaseOffs + MinOffset) > AM.BaseOffs) != + (MinOffset > 0)) + return false; + AM.BaseOffs = (uint64_t)AM.BaseOffs + MinOffset; + if (isLegalUse(AM, Kind, AccessTy, TLI)) { + AM.BaseOffs = (uint64_t)AM.BaseOffs - MinOffset; + // Check for overflow. + if (((int64_t)((uint64_t)AM.BaseOffs + MaxOffset) > AM.BaseOffs) != + (MaxOffset > 0)) + return false; + AM.BaseOffs = (uint64_t)AM.BaseOffs + MaxOffset; + return isLegalUse(AM, Kind, AccessTy, TLI); } - return AccessTy; + return false; } -/// DeleteTriviallyDeadInstructions - If any of the instructions is the -/// specified set are trivially dead, delete them and see if this makes any of -/// their operands subsequently dead. -static bool -DeleteTriviallyDeadInstructions(SmallVectorImpl &DeadInsts) { - bool Changed = false; +static bool isAlwaysFoldable(int64_t BaseOffs, + GlobalValue *BaseGV, + bool HasBaseReg, + LSRUse::KindType Kind, const Type *AccessTy, + const TargetLowering *TLI) { + // Fast-path: zero is always foldable. + if (BaseOffs == 0 && !BaseGV) return true; - while (!DeadInsts.empty()) { - Instruction *I = dyn_cast_or_null(DeadInsts.pop_back_val()); + // Conservatively, create an address with an immediate and a + // base and a scale. + TargetLowering::AddrMode AM; + AM.BaseOffs = BaseOffs; + AM.BaseGV = BaseGV; + AM.HasBaseReg = HasBaseReg; + AM.Scale = Kind == LSRUse::ICmpZero ? -1 : 1; - if (I == 0 || !isInstructionTriviallyDead(I)) - continue; + return isLegalUse(AM, Kind, AccessTy, TLI); +} - for (User::op_iterator OI = I->op_begin(), E = I->op_end(); OI != E; ++OI) - if (Instruction *U = dyn_cast(*OI)) { - *OI = 0; - if (U->use_empty()) - DeadInsts.push_back(U); - } +static bool isAlwaysFoldable(const SCEV *S, + int64_t MinOffset, int64_t MaxOffset, + bool HasBaseReg, + LSRUse::KindType Kind, const Type *AccessTy, + const TargetLowering *TLI, + ScalarEvolution &SE) { + // Fast-path: zero is always foldable. + if (S->isZero()) return true; - I->eraseFromParent(); - Changed = true; - } + // Conservatively, create an address with an immediate and a + // base and a scale. + int64_t BaseOffs = ExtractImmediate(S, SE); + GlobalValue *BaseGV = ExtractSymbol(S, SE); - return Changed; + // If there's anything else involved, it's not foldable. + if (!S->isZero()) return false; + + // Fast-path: zero is always foldable. + if (BaseOffs == 0 && !BaseGV) return true; + + // Conservatively, create an address with an immediate and a + // base and a scale. + TargetLowering::AddrMode AM; + AM.BaseOffs = BaseOffs; + AM.BaseGV = BaseGV; + AM.HasBaseReg = HasBaseReg; + AM.Scale = Kind == LSRUse::ICmpZero ? -1 : 1; + + return isLegalUse(AM, MinOffset, MaxOffset, Kind, AccessTy, TLI); } -namespace { +/// FormulaSorter - This class implements an ordering for formulae which sorts +/// the by their standalone cost. +class FormulaSorter { + /// These two sets are kept empty, so that we compute standalone costs. + DenseSet VisitedRegs; + SmallPtrSet Regs; + Loop *L; + LSRUse *LU; + ScalarEvolution &SE; + DominatorTree &DT; + +public: + FormulaSorter(Loop *l, LSRUse &lu, ScalarEvolution &se, DominatorTree &dt) + : L(l), LU(&lu), SE(se), DT(dt) {} + + bool operator()(const Formula &A, const Formula &B) { + Cost CostA; + CostA.RateFormula(A, Regs, VisitedRegs, L, LU->Offsets, SE, DT); + Regs.clear(); + Cost CostB; + CostB.RateFormula(B, Regs, VisitedRegs, L, LU->Offsets, SE, DT); + Regs.clear(); + return CostA < CostB; + } +}; -/// LSRInstance - This class holds state for the main loop strength -/// reduction logic. +/// LSRInstance - This class holds state for the main loop strength reduction +/// logic. class LSRInstance { IVUsers &IU; ScalarEvolution &SE; @@ -1381,75 +1139,106 @@ class LSRInstance { Loop *const L; bool Changed; - /// CurrentArbitraryRegIndex - To ensure a deterministic ordering, assign an - /// arbitrary index value to each register as a sort tie breaker. - unsigned CurrentArbitraryRegIndex; - - /// MaxNumRegs - To help prune the search for solutions, identify the number - /// of registers needed by the initial solution. No formula should require - /// more than this. - unsigned MaxNumRegs; + /// IVIncInsertPos - This is the insert position that the current loop's + /// induction variable increment should be placed. In simple loops, this is + /// the latch block's terminator. But in more complicated cases, this is a + /// position which will dominate all the in-loop post-increment users. + Instruction *IVIncInsertPos; /// Factors - Interesting factors between use strides. - SmallSetVector Factors; + SmallSetVector Factors; /// Types - Interesting use types, to facilitate truncation reuse. SmallSetVector Types; + /// Fixups - The list of operands which are to be replaced. + SmallVector Fixups; + /// Uses - The list of interesting uses. SmallVector Uses; - // TODO: Reorganize these data structures. - typedef DenseMap RegUsesTy; - RegUsesTy RegUses; - SmallVector RegSequence; + /// RegUses - Track which uses use which register candidates. + RegUseTracker RegUses; void OptimizeShadowIV(); - bool FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse, - const SCEV* &CondStride); + bool FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse); ICmpInst *OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse); - bool StrideMightBeShared(const SCEV* Stride); - bool OptimizeLoopTermCond(Instruction *&IVIncInsertPos); + bool OptimizeLoopTermCond(); - LSRUse &getNewUse() { - Uses.push_back(LSRUse()); - return Uses.back(); - } + void CollectInterestingTypesAndFactors(); + void CollectFixupsAndInitialFormulae(); - void CountRegister(const SCEV *Reg, uint32_t Complexity, size_t LUIdx); - void CountRegisters(const Formula &F, size_t LUIdx); + LSRFixup &getNewFixup() { + Fixups.push_back(LSRFixup()); + return Fixups.back(); + } - bool InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F); + // Support for sharing of LSRUses between LSRFixups. + typedef DenseMap UseMapTy; + UseMapTy UseMap; - void GenerateSymbolicOffsetReuse(LSRUse &LU, unsigned LUIdx, - Formula Base); - void GenerateICmpZeroScaledReuse(LSRUse &LU, unsigned LUIdx, - Formula Base); - void GenerateFormulaeFromReplacedBaseReg(LSRUse &LU, - unsigned LUIdx, - const Formula &Base, unsigned i, - const SmallVectorImpl - &AddOps); - void GenerateReassociationReuse(LSRUse &LU, unsigned LUIdx, - Formula Base); - void GenerateCombinationReuse(LSRUse &LU, unsigned LUIdx, - Formula Base); - void GenerateScaledReuse(LSRUse &LU, unsigned LUIdx, - Formula Base); - void GenerateTruncateReuse(LSRUse &LU, unsigned LUIdx, - Formula Base); - - void GenerateConstantOffsetReuse(); + bool reconcileNewOffset(LSRUse &LU, int64_t NewOffset, + LSRUse::KindType Kind, const Type *AccessTy); - void GenerateAllReuseFormulae(); - - void GenerateLoopInvariantRegisterUses(); + std::pair getUse(const SCEV *&Expr, + LSRUse::KindType Kind, + const Type *AccessTy); public: + void InsertInitialFormula(const SCEV *S, LSRUse &LU, size_t LUIdx); + void InsertSupplementalFormula(const SCEV *S, LSRUse &LU, size_t LUIdx); + void CountRegisters(const Formula &F, size_t LUIdx); + bool InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F); + + void CollectLoopInvariantFixupsAndFormulae(); + + void GenerateReassociations(LSRUse &LU, unsigned LUIdx, Formula Base, + unsigned Depth = 0); + void GenerateCombinations(LSRUse &LU, unsigned LUIdx, Formula Base); + void GenerateSymbolicOffsets(LSRUse &LU, unsigned LUIdx, Formula Base); + void GenerateConstantOffsets(LSRUse &LU, unsigned LUIdx, Formula Base); + void GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx, Formula Base); + void GenerateScales(LSRUse &LU, unsigned LUIdx, Formula Base); + void GenerateTruncates(LSRUse &LU, unsigned LUIdx, Formula Base); + void GenerateCrossUseConstantOffsets(); + void GenerateAllReuseFormulae(); + + void FilterOutUndesirableDedicatedRegisters(); + void NarrowSearchSpaceUsingHeuristics(); + + void SolveRecurse(SmallVectorImpl &Solution, + Cost &SolutionCost, + SmallVectorImpl &Workspace, + const Cost &CurCost, + const SmallPtrSet &CurRegs, + DenseSet &VisitedRegs) const; + void Solve(SmallVectorImpl &Solution) const; + + Value *Expand(const LSRFixup &LF, + const Formula &F, + BasicBlock::iterator IP, + SCEVExpander &Rewriter, + SmallVectorImpl &DeadInsts) const; + void RewriteForPHI(PHINode *PN, const LSRFixup &LF, + const Formula &F, + SCEVExpander &Rewriter, + SmallVectorImpl &DeadInsts, + Pass *P) const; + void Rewrite(const LSRFixup &LF, + const Formula &F, + SCEVExpander &Rewriter, + SmallVectorImpl &DeadInsts, + Pass *P) const; + void ImplementSolution(const SmallVectorImpl &Solution, + Pass *P); + LSRInstance(const TargetLowering *tli, Loop *l, Pass *P); bool getChanged() const { return Changed; } + void print_factors_and_types(raw_ostream &OS) const; + void print_fixups(raw_ostream &OS) const; + void print_uses(raw_ostream &OS) const; void print(raw_ostream &OS) const; void dump() const; }; @@ -1457,115 +1246,106 @@ public: } /// OptimizeShadowIV - If IV is used in a int-to-float cast -/// inside the loop then try to eliminate the cast opeation. +/// inside the loop then try to eliminate the cast operation. void LSRInstance::OptimizeShadowIV() { const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(L); if (isa(BackedgeTakenCount)) return; - for (size_t StrideIdx = 0, e = IU.StrideOrder.size(); - StrideIdx != e; ++StrideIdx) { - std::map::iterator SI = - IU.IVUsesByStride.find(IU.StrideOrder[StrideIdx]); - assert(SI != IU.IVUsesByStride.end() && "Stride doesn't exist!"); - if (!isa(SI->first)) - continue; - - for (ilist::iterator UI = SI->second->Users.begin(), - E = SI->second->Users.end(); UI != E; /* empty */) { - ilist::iterator CandidateUI = UI; - ++UI; - Instruction *ShadowUse = CandidateUI->getUser(); - const Type *DestTy = NULL; - - /* If shadow use is a int->float cast then insert a second IV - to eliminate this cast. - - for (unsigned i = 0; i < n; ++i) - foo((double)i); - - is transformed into - - double d = 0.0; - for (unsigned i = 0; i < n; ++i, ++d) - foo(d); - */ - if (UIToFPInst *UCast = dyn_cast(CandidateUI->getUser())) - DestTy = UCast->getDestTy(); - else if (SIToFPInst *SCast = dyn_cast(CandidateUI->getUser())) - DestTy = SCast->getDestTy(); - if (!DestTy) continue; - - if (TLI) { - // If target does not support DestTy natively then do not apply - // this transformation. - EVT DVT = TLI->getValueType(DestTy); - if (!TLI->isTypeLegal(DVT)) continue; - } + for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); + UI != E; /* empty */) { + IVUsers::const_iterator CandidateUI = UI; + ++UI; + Instruction *ShadowUse = CandidateUI->getUser(); + const Type *DestTy = NULL; + + /* If shadow use is a int->float cast then insert a second IV + to eliminate this cast. + + for (unsigned i = 0; i < n; ++i) + foo((double)i); + + is transformed into + + double d = 0.0; + for (unsigned i = 0; i < n; ++i, ++d) + foo(d); + */ + if (UIToFPInst *UCast = dyn_cast(CandidateUI->getUser())) + DestTy = UCast->getDestTy(); + else if (SIToFPInst *SCast = dyn_cast(CandidateUI->getUser())) + DestTy = SCast->getDestTy(); + if (!DestTy) continue; + + if (TLI) { + // If target does not support DestTy natively then do not apply + // this transformation. + EVT DVT = TLI->getValueType(DestTy); + if (!TLI->isTypeLegal(DVT)) continue; + } - PHINode *PH = dyn_cast(ShadowUse->getOperand(0)); - if (!PH) continue; - if (PH->getNumIncomingValues() != 2) continue; + PHINode *PH = dyn_cast(ShadowUse->getOperand(0)); + if (!PH) continue; + if (PH->getNumIncomingValues() != 2) continue; - const Type *SrcTy = PH->getType(); - int Mantissa = DestTy->getFPMantissaWidth(); - if (Mantissa == -1) continue; - if ((int)SE.getTypeSizeInBits(SrcTy) > Mantissa) - continue; + const Type *SrcTy = PH->getType(); + int Mantissa = DestTy->getFPMantissaWidth(); + if (Mantissa == -1) continue; + if ((int)SE.getTypeSizeInBits(SrcTy) > Mantissa) + continue; - unsigned Entry, Latch; - if (PH->getIncomingBlock(0) == L->getLoopPreheader()) { - Entry = 0; - Latch = 1; - } else { - Entry = 1; - Latch = 0; - } + unsigned Entry, Latch; + if (PH->getIncomingBlock(0) == L->getLoopPreheader()) { + Entry = 0; + Latch = 1; + } else { + Entry = 1; + Latch = 0; + } - ConstantInt *Init = dyn_cast(PH->getIncomingValue(Entry)); - if (!Init) continue; - Constant *NewInit = ConstantFP::get(DestTy, Init->getZExtValue()); + ConstantInt *Init = dyn_cast(PH->getIncomingValue(Entry)); + if (!Init) continue; + Constant *NewInit = ConstantFP::get(DestTy, Init->getZExtValue()); - BinaryOperator *Incr = - dyn_cast(PH->getIncomingValue(Latch)); - if (!Incr) continue; - if (Incr->getOpcode() != Instruction::Add - && Incr->getOpcode() != Instruction::Sub) - continue; + BinaryOperator *Incr = + dyn_cast(PH->getIncomingValue(Latch)); + if (!Incr) continue; + if (Incr->getOpcode() != Instruction::Add + && Incr->getOpcode() != Instruction::Sub) + continue; - /* Initialize new IV, double d = 0.0 in above example. */ - ConstantInt *C = NULL; - if (Incr->getOperand(0) == PH) - C = dyn_cast(Incr->getOperand(1)); - else if (Incr->getOperand(1) == PH) - C = dyn_cast(Incr->getOperand(0)); - else - continue; + /* Initialize new IV, double d = 0.0 in above example. */ + ConstantInt *C = NULL; + if (Incr->getOperand(0) == PH) + C = dyn_cast(Incr->getOperand(1)); + else if (Incr->getOperand(1) == PH) + C = dyn_cast(Incr->getOperand(0)); + else + continue; - if (!C) continue; + if (!C) continue; - // Ignore negative constants, as the code below doesn't handle them - // correctly. TODO: Remove this restriction. - if (!C->getValue().isStrictlyPositive()) continue; + // Ignore negative constants, as the code below doesn't handle them + // correctly. TODO: Remove this restriction. + if (!C->getValue().isStrictlyPositive()) continue; - /* Add new PHINode. */ - PHINode *NewPH = PHINode::Create(DestTy, "IV.S.", PH); + /* Add new PHINode. */ + PHINode *NewPH = PHINode::Create(DestTy, "IV.S.", PH); - /* create new increment. '++d' in above example. */ - Constant *CFP = ConstantFP::get(DestTy, C->getZExtValue()); - BinaryOperator *NewIncr = - BinaryOperator::Create(Incr->getOpcode() == Instruction::Add ? - Instruction::FAdd : Instruction::FSub, - NewPH, CFP, "IV.S.next.", Incr); + /* create new increment. '++d' in above example. */ + Constant *CFP = ConstantFP::get(DestTy, C->getZExtValue()); + BinaryOperator *NewIncr = + BinaryOperator::Create(Incr->getOpcode() == Instruction::Add ? + Instruction::FAdd : Instruction::FSub, + NewPH, CFP, "IV.S.next.", Incr); - NewPH->addIncoming(NewInit, PH->getIncomingBlock(Entry)); - NewPH->addIncoming(NewIncr, PH->getIncomingBlock(Latch)); + NewPH->addIncoming(NewInit, PH->getIncomingBlock(Entry)); + NewPH->addIncoming(NewIncr, PH->getIncomingBlock(Latch)); - /* Remove cast operation */ - ShadowUse->replaceAllUsesWith(NewPH); - ShadowUse->eraseFromParent(); - break; - } + /* Remove cast operation */ + ShadowUse->replaceAllUsesWith(NewPH); + ShadowUse->eraseFromParent(); + break; } } @@ -1573,25 +1353,15 @@ void LSRInstance::OptimizeShadowIV() { /// set the IV user and stride information and return true, otherwise return /// false. bool LSRInstance::FindIVUserForCond(ICmpInst *Cond, - IVStrideUse *&CondUse, - const SCEV* &CondStride) { - for (unsigned StrideIdx = 0, e = IU.StrideOrder.size(); - StrideIdx != e && !CondUse; ++StrideIdx) { - std::map::iterator SI = - IU.IVUsesByStride.find(IU.StrideOrder[StrideIdx]); - assert(SI != IU.IVUsesByStride.end() && "Stride doesn't exist!"); - - for (ilist::iterator UI = SI->second->Users.begin(), - E = SI->second->Users.end(); UI != E; ++UI) - if (UI->getUser() == Cond) { - // NOTE: we could handle setcc instructions with multiple uses here, but - // InstCombine does it as well for simple uses, it's not clear that it - // occurs enough in real life to handle. - CondUse = UI; - CondStride = SI->first; - return true; - } - } + IVStrideUse *&CondUse) { + for (IVUsers::iterator UI = IU.begin(), E = IU.end(); UI != E; ++UI) + if (UI->getUser() == Cond) { + // NOTE: we could handle setcc instructions with multiple uses here, but + // InstCombine does it as well for simple uses, it's not clear that it + // occurs enough in real life to handle. + CondUse = UI; + return true; + } return false; } @@ -1720,48 +1490,10 @@ ICmpInst *LSRInstance::OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse) { return NewCond; } -bool LSRInstance::StrideMightBeShared(const SCEV* Stride) { - int64_t SInt = cast(Stride)->getValue()->getSExtValue(); - for (unsigned i = 0, e = IU.StrideOrder.size(); i != e; ++i) { - std::map::iterator SI = - IU.IVUsesByStride.find(IU.StrideOrder[i]); - const SCEV *Share = SI->first; - if (!isa(SI->first) || Share == Stride) - continue; - int64_t SSInt = cast(Share)->getValue()->getSExtValue(); - if (SSInt == SInt) - return true; // This can definitely be reused. - if (unsigned(abs64(SSInt)) < SInt || (SSInt % SInt) != 0) - continue; - int64_t Scale = SSInt / SInt; - - // This AM will be used for conservative queries. At this point in the - // process we don't know which users will have a base reg, immediate, - // etc., so we conservatively assume that it may not, making more - // strides valid, thus erring on the side of assuming that there - // might be sharing. - TargetLowering::AddrMode AM; - AM.Scale = Scale; - - // Any pre-inc iv use? - IVUsersOfOneStride &StrideUses = *IU.IVUsesByStride[Share]; - for (ilist::iterator I = StrideUses.Users.begin(), - E = StrideUses.Users.end(); I != E; ++I) { - bool isAddress = isAddressUse(I->getUser(), I->getOperandValToReplace()); - if (!I->isUseOfPostIncrementedValue() && - isLegalUse(AM, isAddress ? LSRUse::Address : LSRUse::Basic, - isAddress ? getAccessType(I->getUser()) : 0, - TLI)) - return true; - } - } - return false; -} - /// OptimizeLoopTermCond - Change loop terminating condition to use the /// postinc iv when possible. bool -LSRInstance::OptimizeLoopTermCond(Instruction *&IVIncInsertPos) { +LSRInstance::OptimizeLoopTermCond() { SmallPtrSet PostIncs; BasicBlock *LatchBlock = L->getLoopLatch(); @@ -1785,9 +1517,8 @@ LSRInstance::OptimizeLoopTermCond(Instruction *&IVIncInsertPos) { // Search IVUsesByStride to find Cond's IVUse if there is one. IVStrideUse *CondUse = 0; - const SCEV *CondStride = 0; ICmpInst *Cond = cast(TermBr->getCondition()); - if (!FindIVUserForCond(Cond, CondUse, CondStride)) + if (!FindIVUserForCond(Cond, CondUse)) continue; // If the trip count is computed in terms of a max (due to ScalarEvolution @@ -1798,48 +1529,57 @@ LSRInstance::OptimizeLoopTermCond(Instruction *&IVIncInsertPos) { // cases it may still be worthwhile to avoid a max. Cond = OptimizeMax(Cond, CondUse); - // If this exiting block is the latch block, and the condition has only - // one use inside the loop (the branch), use the post-incremented value - // of the induction variable - if (ExitingBlock != LatchBlock) { - // If this exiting block dominates the latch block, it may also use - // the post-inc value if it won't be shared with other uses. - // Check for dominance. - if (!DT.dominates(ExitingBlock, LatchBlock)) - continue; - // Check for sharing within the same stride. - bool SameStrideSharing = false; - IVUsersOfOneStride &StrideUses = *IU.IVUsesByStride[CondStride]; - for (ilist::iterator I = StrideUses.Users.begin(), - E = StrideUses.Users.end(); I != E; ++I) { - if (I->getUser() == Cond) - continue; - if (!I->isUseOfPostIncrementedValue()) { - SameStrideSharing = true; - break; - } - } - if (SameStrideSharing) - continue; - // Check for sharing from a different stride. - if (isa(CondStride) && StrideMightBeShared(CondStride)) - continue; - } - if (!Cond->hasOneUse()) { - bool HasOneUseInLoop = true; - for (Value::use_iterator UI = Cond->use_begin(), UE = Cond->use_end(); - UI != UE; ++UI) { - Instruction *U = cast(*UI); - if (U == TermBr) - continue; - if (L->contains(U)) { - HasOneUseInLoop = false; - break; + // If this exiting block dominates the latch block, it may also use + // the post-inc value if it won't be shared with other uses. + // Check for dominance. + if (!DT.dominates(ExitingBlock, LatchBlock)) + continue; + + // Conservatively avoid trying to use the post-inc value in non-latch + // exits if there may be pre-inc users in intervening blocks. + if (LatchBlock != ExitingBlock) + for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); UI != E; ++UI) + // Test if the use is reachable from the exiting block. This dominator + // query is a conservative approximation of reachability. + if (&*UI != CondUse && + !DT.properlyDominates(UI->getUser()->getParent(), ExitingBlock)) { + // Conservatively assume there may be reuse if the quotient of their + // strides could be a legal scale. + const SCEV *A = CondUse->getStride(); + const SCEV *B = UI->getStride(); + if (SE.getTypeSizeInBits(A->getType()) != + SE.getTypeSizeInBits(B->getType())) { + if (SE.getTypeSizeInBits(A->getType()) > + SE.getTypeSizeInBits(B->getType())) + B = SE.getSignExtendExpr(B, A->getType()); + else + A = SE.getSignExtendExpr(A, B->getType()); + } + if (const SCEVConstant *D = + dyn_cast_or_null(getExactSDiv(B, A, SE))) { + // Stride of one or negative one can have reuse with non-addresses. + if (D->getValue()->isOne() || + D->getValue()->isAllOnesValue()) + goto decline_post_inc; + // Avoid weird situations. + if (D->getValue()->getValue().getMinSignedBits() >= 64 || + D->getValue()->getValue().isMinSignedValue()) + goto decline_post_inc; + // Without TLI, assume that any stride might be valid, and so any + // use might be shared. + if (!TLI) + goto decline_post_inc; + // Check for possible scaled-address reuse. + const Type *AccessTy = getAccessType(UI->getUser()); + TargetLowering::AddrMode AM; + AM.Scale = D->getValue()->getSExtValue(); + if (TLI->isLegalAddressingMode(AM, AccessTy)) + goto decline_post_inc; + AM.Scale = -AM.Scale; + if (TLI->isLegalAddressingMode(AM, AccessTy)) + goto decline_post_inc; + } } - } - if (!HasOneUseInLoop) - continue; - } DEBUG(dbgs() << " Change loop exiting icmp to use postinc iv: " << *Cond << '\n'); @@ -1848,20 +1588,18 @@ LSRInstance::OptimizeLoopTermCond(Instruction *&IVIncInsertPos) { // possible for it to have multiple users. If it is not immediately before // the exiting block branch, move it. if (&*++BasicBlock::iterator(Cond) != TermBr) { - if (Cond->hasOneUse()) { // Condition has a single use, just move it. + if (Cond->hasOneUse()) { Cond->moveBefore(TermBr); } else { - // Otherwise, clone the terminating condition and insert into the - // loopend. + // Clone the terminating condition and insert into the loopend. ICmpInst *OldCond = Cond; Cond = cast(Cond->clone()); Cond->setName(L->getHeader()->getName() + ".termcond"); ExitingBlock->getInstList().insert(TermBr, Cond); // Clone the IVUse, as the old use still exists! - IU.IVUsesByStride[CondStride]->addUser(CondUse->getOffset(), Cond, - CondUse->getOperandValToReplace()); - CondUse = &IU.IVUsesByStride[CondStride]->Users.back(); + CondUse = &IU.AddUser(CondUse->getStride(), CondUse->getOffset(), + Cond, CondUse->getOperandValToReplace()); TermBr->replaceUsesOfWith(OldCond, Cond); } } @@ -1869,18 +1607,20 @@ LSRInstance::OptimizeLoopTermCond(Instruction *&IVIncInsertPos) { // If we get to here, we know that we can transform the setcc instruction to // use the post-incremented version of the IV, allowing us to coalesce the // live ranges for the IV correctly. - CondUse->setOffset(SE.getMinusSCEV(CondUse->getOffset(), CondStride)); + CondUse->setOffset(SE.getMinusSCEV(CondUse->getOffset(), + CondUse->getStride())); CondUse->setIsUseOfPostIncrementedValue(true); Changed = true; PostIncs.insert(Cond); + decline_post_inc:; } // Determine an insertion point for the loop induction variable increment. It // must dominate all the post-inc comparisons we just set up, and it must // dominate the loop latch edge. IVIncInsertPos = L->getLoopLatch()->getTerminator(); - for (SmallPtrSet::iterator I = PostIncs.begin(), + for (SmallPtrSet::const_iterator I = PostIncs.begin(), E = PostIncs.end(); I != E; ++I) { BasicBlock *BB = DT.findNearestCommonDominator(IVIncInsertPos->getParent(), @@ -1894,213 +1634,408 @@ LSRInstance::OptimizeLoopTermCond(Instruction *&IVIncInsertPos) { return Changed; } -/// CountRegisters - Note the given register. -void LSRInstance::CountRegister(const SCEV *Reg, uint32_t Complexity, - size_t LUIdx) { - std::pair Pair = - RegUses.insert(std::make_pair(Reg, RegSortData())); - RegSortData &BV = Pair.first->second; - if (Pair.second) { - BV.Index = CurrentArbitraryRegIndex++; - BV.MaxComplexity = Complexity; - RegSequence.push_back(Reg); - } else { - BV.MaxComplexity = std::max(BV.MaxComplexity, Complexity); +bool +LSRInstance::reconcileNewOffset(LSRUse &LU, int64_t NewOffset, + LSRUse::KindType Kind, const Type *AccessTy) { + int64_t NewMinOffset = LU.MinOffset; + int64_t NewMaxOffset = LU.MaxOffset; + const Type *NewAccessTy = AccessTy; + + // Check for a mismatched kind. It's tempting to collapse mismatched kinds to + // something conservative, however this can pessimize in the case that one of + // the uses will have all its uses outside the loop, for example. + if (LU.Kind != Kind) + return false; + // Conservatively assume HasBaseReg is true for now. + if (NewOffset < LU.MinOffset) { + if (!isAlwaysFoldable(LU.MaxOffset - NewOffset, 0, /*HasBaseReg=*/true, + Kind, AccessTy, TLI)) + return false; + NewMinOffset = NewOffset; + } else if (NewOffset > LU.MaxOffset) { + if (!isAlwaysFoldable(NewOffset - LU.MinOffset, 0, /*HasBaseReg=*/true, + Kind, AccessTy, TLI)) + return false; + NewMaxOffset = NewOffset; } - BV.Bits.resize(std::max(BV.Bits.size(), LUIdx + 1)); - BV.Bits.set(LUIdx); + // Check for a mismatched access type, and fall back conservatively as needed. + if (Kind == LSRUse::Address && AccessTy != LU.AccessTy) + NewAccessTy = Type::getVoidTy(AccessTy->getContext()); + + // Update the use. + LU.MinOffset = NewMinOffset; + LU.MaxOffset = NewMaxOffset; + LU.AccessTy = NewAccessTy; + if (NewOffset != LU.Offsets.back()) + LU.Offsets.push_back(NewOffset); + return true; +} + +/// getUse - Return an LSRUse index and an offset value for a fixup which +/// needs the given expression, with the given kind and optional access type. +/// Either reuse an existing use or create a new one, as needed. +std::pair +LSRInstance::getUse(const SCEV *&Expr, + LSRUse::KindType Kind, const Type *AccessTy) { + const SCEV *Copy = Expr; + int64_t Offset = ExtractImmediate(Expr, SE); + + // Basic uses can't accept any offset, for example. + if (!isAlwaysFoldable(Offset, 0, /*HasBaseReg=*/true, Kind, AccessTy, TLI)) { + Expr = Copy; + Offset = 0; + } + + std::pair P = + UseMap.insert(std::make_pair(Expr, 0)); + if (!P.second) { + // A use already existed with this base. + size_t LUIdx = P.first->second; + LSRUse &LU = Uses[LUIdx]; + if (reconcileNewOffset(LU, Offset, Kind, AccessTy)) + // Reuse this use. + return std::make_pair(LUIdx, Offset); + } + + // Create a new use. + size_t LUIdx = Uses.size(); + P.first->second = LUIdx; + Uses.push_back(LSRUse(Kind, AccessTy)); + LSRUse &LU = Uses[LUIdx]; + + // We don't need to track redundant offsets, but we don't need to go out + // of our way here to avoid them. + if (LU.Offsets.empty() || Offset != LU.Offsets.back()) + LU.Offsets.push_back(Offset); + + LU.MinOffset = Offset; + LU.MaxOffset = Offset; + return std::make_pair(LUIdx, Offset); +} + +void LSRInstance::CollectInterestingTypesAndFactors() { + SmallSetVector Strides; + + // Collect interesting types and strides. + for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); UI != E; ++UI) { + const SCEV *Stride = UI->getStride(); + + // Collect interesting types. + Types.insert(SE.getEffectiveSCEVType(Stride->getType())); + + // Add the stride for this loop. + Strides.insert(Stride); + + // Add strides for other mentioned loops. + for (const SCEVAddRecExpr *AR = dyn_cast(UI->getOffset()); + AR; AR = dyn_cast(AR->getStart())) + Strides.insert(AR->getStepRecurrence(SE)); + } + + // Compute interesting factors from the set of interesting strides. + for (SmallSetVector::const_iterator + I = Strides.begin(), E = Strides.end(); I != E; ++I) + for (SmallSetVector::const_iterator NewStrideIter = + next(I); NewStrideIter != E; ++NewStrideIter) { + const SCEV *OldStride = *I; + const SCEV *NewStride = *NewStrideIter; + + if (SE.getTypeSizeInBits(OldStride->getType()) != + SE.getTypeSizeInBits(NewStride->getType())) { + if (SE.getTypeSizeInBits(OldStride->getType()) > + SE.getTypeSizeInBits(NewStride->getType())) + NewStride = SE.getSignExtendExpr(NewStride, OldStride->getType()); + else + OldStride = SE.getSignExtendExpr(OldStride, NewStride->getType()); + } + if (const SCEVConstant *Factor = + dyn_cast_or_null(getExactSDiv(NewStride, OldStride, + SE, true))) { + if (Factor->getValue()->getValue().getMinSignedBits() <= 64) + Factors.insert(Factor->getValue()->getValue().getSExtValue()); + } else if (const SCEVConstant *Factor = + dyn_cast_or_null(getExactSDiv(OldStride, + NewStride, + SE, true))) { + if (Factor->getValue()->getValue().getMinSignedBits() <= 64) + Factors.insert(Factor->getValue()->getValue().getSExtValue()); + } + } + + // If all uses use the same type, don't bother looking for truncation-based + // reuse. + if (Types.size() == 1) + Types.clear(); + + DEBUG(print_factors_and_types(dbgs())); +} + +void LSRInstance::CollectFixupsAndInitialFormulae() { + for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); UI != E; ++UI) { + // Record the uses. + LSRFixup &LF = getNewFixup(); + LF.UserInst = UI->getUser(); + LF.OperandValToReplace = UI->getOperandValToReplace(); + if (UI->isUseOfPostIncrementedValue()) + LF.PostIncLoop = L; + + LSRUse::KindType Kind = LSRUse::Basic; + const Type *AccessTy = 0; + if (isAddressUse(LF.UserInst, LF.OperandValToReplace)) { + Kind = LSRUse::Address; + AccessTy = getAccessType(LF.UserInst); + } + + const SCEV *S = IU.getCanonicalExpr(*UI); + + // Equality (== and !=) ICmps are special. We can rewrite (i == N) as + // (N - i == 0), and this allows (N - i) to be the expression that we work + // with rather than just N or i, so we can consider the register + // requirements for both N and i at the same time. Limiting this code to + // equality icmps is not a problem because all interesting loops use + // equality icmps, thanks to IndVarSimplify. + if (ICmpInst *CI = dyn_cast(LF.UserInst)) + if (CI->isEquality()) { + // Swap the operands if needed to put the OperandValToReplace on the + // left, for consistency. + Value *NV = CI->getOperand(1); + if (NV == LF.OperandValToReplace) { + CI->setOperand(1, CI->getOperand(0)); + CI->setOperand(0, NV); + } + + // x == y --> x - y == 0 + const SCEV *N = SE.getSCEV(NV); + if (N->isLoopInvariant(L)) { + Kind = LSRUse::ICmpZero; + S = SE.getMinusSCEV(N, S); + } + + // -1 and the negations of all interesting strides (except the negation + // of -1) are now also interesting. + for (size_t i = 0, e = Factors.size(); i != e; ++i) + if (Factors[i] != -1) + Factors.insert(-(uint64_t)Factors[i]); + Factors.insert(-1); + } + + // Set up the initial formula for this use. + std::pair P = getUse(S, Kind, AccessTy); + LF.LUIdx = P.first; + LF.Offset = P.second; + LSRUse &LU = Uses[LF.LUIdx]; + LU.AllFixupsOutsideLoop &= !L->contains(LF.UserInst); + + // If this is the first use of this LSRUse, give it a formula. + if (LU.Formulae.empty()) { + InsertInitialFormula(S, LU, LF.LUIdx); + CountRegisters(LU.Formulae.back(), LF.LUIdx); + } + } + + DEBUG(print_fixups(dbgs())); +} + +void +LSRInstance::InsertInitialFormula(const SCEV *S, LSRUse &LU, size_t LUIdx) { + Formula F; + F.InitialMatch(S, L, SE, DT); + bool Inserted = InsertFormula(LU, LUIdx, F); + assert(Inserted && "Initial formula already exists!"); (void)Inserted; +} + +void +LSRInstance::InsertSupplementalFormula(const SCEV *S, + LSRUse &LU, size_t LUIdx) { + Formula F; + F.BaseRegs.push_back(S); + F.AM.HasBaseReg = true; + bool Inserted = InsertFormula(LU, LUIdx, F); + assert(Inserted && "Supplemental formula already exists!"); (void)Inserted; } /// CountRegisters - Note which registers are used by the given formula, /// updating RegUses. void LSRInstance::CountRegisters(const Formula &F, size_t LUIdx) { - uint32_t Complexity = F.getComplexity(); if (F.ScaledReg) - CountRegister(F.ScaledReg, Complexity, LUIdx); + RegUses.CountRegister(F.ScaledReg, LUIdx); for (SmallVectorImpl::const_iterator I = F.BaseRegs.begin(), E = F.BaseRegs.end(); I != E; ++I) - CountRegister(*I, Complexity, LUIdx); + RegUses.CountRegister(*I, LUIdx); } -/// InsertFormula - If the given formula has not yet been inserted, add it -/// to the list, and return true. Return false otherwise. +/// InsertFormula - If the given formula has not yet been inserted, add it to +/// the list, and return true. Return false otherwise. bool LSRInstance::InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F) { - // If a formula by itself would require more registers than the base solution, - // discard it and stop searching from it, as it won't be profitable. This is - // actually more permissive than it could be, because it doesn't include - // registers used by non-constant strides in F. - if (F.getNumRegs() > MaxNumRegs) - return false; - if (!LU.InsertFormula(F)) return false; - CountRegisters(LU.Formulae.back(), LUIdx); + CountRegisters(F, LUIdx); return true; } -/// GenerateSymbolicOffsetReuse - Generate reuse formulae using symbolic -/// offsets. -void LSRInstance::GenerateSymbolicOffsetReuse(LSRUse &LU, unsigned LUIdx, - Formula Base) { - // We can't add a symbolic offset if the address already contains one. - if (Base.AM.BaseGV) return; - - for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) { - const SCEV *G = Base.BaseRegs[i]; - GlobalValue *GV = ExtractSymbol(G, SE); - if (G->isZero()) - continue; - Formula F = Base; - F.AM.BaseGV = GV; - if (!isLegalUse(F.AM, LU.Kind, LU.AccessTy, TLI)) - continue; - F.BaseRegs[i] = G; - (void)InsertFormula(LU, LUIdx, F); - } -} - -/// GenerateICmpZeroScaledReuse - For ICmpZero, check to see if we can scale up -/// the comparison. For example, x == y -> x*c == y*c. -void LSRInstance::GenerateICmpZeroScaledReuse(LSRUse &LU, unsigned LUIdx, - Formula Base) { - if (LU.Kind != LSRUse::ICmpZero) return; - - // Determine the integer type for the base formula. - const Type *IntTy = Base.getType(); - if (!IntTy) return; - if (SE.getTypeSizeInBits(IntTy) > 64) return; - IntTy = SE.getEffectiveSCEVType(IntTy); - - assert(!Base.AM.BaseGV && "ICmpZero use is not legal!"); - - // Check each interesting stride. - for (SmallSetVector::const_iterator - I = Factors.begin(), E = Factors.end(); I != E; ++I) { - int64_t Factor = *I; - Formula F = Base; - - // Check that the multiplication doesn't overflow. - F.AM.BaseOffs = (uint64_t)F.AM.BaseOffs * Factor; - if ((int64_t)F.AM.BaseOffs / Factor != F.AM.BaseOffs) - continue; +/// CollectLoopInvariantFixupsAndFormulae - Check for other uses of +/// loop-invariant values which we're tracking. These other uses will pin these +/// values in registers, making them less profitable for elimination. +/// TODO: This currently misses non-constant addrec step registers. +/// TODO: Should this give more weight to users inside the loop? +void +LSRInstance::CollectLoopInvariantFixupsAndFormulae() { + SmallVector Worklist(RegUses.begin(), RegUses.end()); + SmallPtrSet Inserted; - // Check that this scale is legal. - if (!isLegalUse(F.AM, LU.Kind, LU.AccessTy, TLI)) - continue; + while (!Worklist.empty()) { + const SCEV *S = Worklist.pop_back_val(); - const SCEV *FactorS = SE.getSCEV(ConstantInt::get(IntTy, Factor)); + if (const SCEVNAryExpr *N = dyn_cast(S)) + Worklist.insert(Worklist.end(), N->op_begin(), N->op_end()); + else if (const SCEVCastExpr *C = dyn_cast(S)) + Worklist.push_back(C->getOperand()); + else if (const SCEVUDivExpr *D = dyn_cast(S)) { + Worklist.push_back(D->getLHS()); + Worklist.push_back(D->getRHS()); + } else if (const SCEVUnknown *U = dyn_cast(S)) { + if (!Inserted.insert(U)) continue; + const Value *V = U->getValue(); + if (const Instruction *Inst = dyn_cast(V)) + if (L->contains(Inst)) continue; + for (Value::use_const_iterator UI = V->use_begin(), UE = V->use_end(); + UI != UE; ++UI) { + const Instruction *UserInst = dyn_cast(*UI); + // Ignore non-instructions. + if (!UserInst) + continue; + // Ignore instructions in other functions (as can happen with + // Constants). + if (UserInst->getParent()->getParent() != L->getHeader()->getParent()) + continue; + // Ignore instructions not dominated by the loop. + const BasicBlock *UseBB = !isa(UserInst) ? + UserInst->getParent() : + cast(UserInst)->getIncomingBlock( + PHINode::getIncomingValueNumForOperand(UI.getOperandNo())); + if (!DT.dominates(L->getHeader(), UseBB)) + continue; + // Ignore uses which are part of other SCEV expressions, to avoid + // analyzing them multiple times. + if (SE.isSCEVable(UserInst->getType()) && + !isa(SE.getSCEV(const_cast(UserInst)))) + continue; + // Ignore icmp instructions which are already being analyzed. + if (const ICmpInst *ICI = dyn_cast(UserInst)) { + unsigned OtherIdx = !UI.getOperandNo(); + Value *OtherOp = const_cast(ICI->getOperand(OtherIdx)); + if (SE.getSCEV(OtherOp)->hasComputableLoopEvolution(L)) + continue; + } - // Check that multiplying with each base register doesn't overflow. - for (size_t i = 0, e = F.BaseRegs.size(); i != e; ++i) { - F.BaseRegs[i] = SE.getMulExpr(F.BaseRegs[i], FactorS); - if (getSDiv(F.BaseRegs[i], FactorS, SE) != Base.BaseRegs[i]) - goto next; + LSRFixup &LF = getNewFixup(); + LF.UserInst = const_cast(UserInst); + LF.OperandValToReplace = UI.getUse(); + std::pair P = getUse(S, LSRUse::Basic, 0); + LF.LUIdx = P.first; + LF.Offset = P.second; + LSRUse &LU = Uses[LF.LUIdx]; + LU.AllFixupsOutsideLoop &= L->contains(LF.UserInst); + InsertSupplementalFormula(U, LU, LF.LUIdx); + CountRegisters(LU.Formulae.back(), Uses.size() - 1); + break; + } } + } +} - // Check that multiplying with the scaled register doesn't overflow. - if (F.ScaledReg) { - F.ScaledReg = SE.getMulExpr(F.ScaledReg, FactorS); - if (getSDiv(F.ScaledReg, FactorS, SE) != Base.ScaledReg) - continue; +/// CollectSubexprs - Split S into subexpressions which can be pulled out into +/// separate registers. If C is non-null, multiply each subexpression by C. +static void CollectSubexprs(const SCEV *S, const SCEVConstant *C, + SmallVectorImpl &Ops, + ScalarEvolution &SE) { + if (const SCEVAddExpr *Add = dyn_cast(S)) { + // Break out add operands. + for (SCEVAddExpr::op_iterator I = Add->op_begin(), E = Add->op_end(); + I != E; ++I) + CollectSubexprs(*I, C, Ops, SE); + return; + } else if (const SCEVAddRecExpr *AR = dyn_cast(S)) { + // Split a non-zero base out of an addrec. + if (!AR->getStart()->isZero()) { + CollectSubexprs(SE.getAddRecExpr(SE.getIntegerSCEV(0, AR->getType()), + AR->getStepRecurrence(SE), + AR->getLoop()), C, Ops, SE); + CollectSubexprs(AR->getStart(), C, Ops, SE); + return; } - - // If we make it here and it's legal, add it. - (void)InsertFormula(LU, LUIdx, F); - next:; + } else if (const SCEVMulExpr *Mul = dyn_cast(S)) { + // Break (C * (a + b + c)) into C*a + C*b + C*c. + if (Mul->getNumOperands() == 2) + if (const SCEVConstant *Op0 = + dyn_cast(Mul->getOperand(0))) { + CollectSubexprs(Mul->getOperand(1), + C ? cast(SE.getMulExpr(C, Op0)) : Op0, + Ops, SE); + return; + } } + + // Otherwise use the value itself. + Ops.push_back(C ? SE.getMulExpr(C, S) : S); } -/// GenerateFormulaeFromReplacedBaseReg - If removing base register with -/// index i from the BaseRegs list and adding the registers in AddOps -/// to the address forms an interesting formula, pursue it. -void -LSRInstance::GenerateFormulaeFromReplacedBaseReg( - LSRUse &LU, - unsigned LUIdx, - const Formula &Base, unsigned i, - const SmallVectorImpl - &AddOps) { - if (AddOps.empty()) return; +/// GenerateReassociations - Split out subexpressions from adds and the bases of +/// addrecs. +void LSRInstance::GenerateReassociations(LSRUse &LU, unsigned LUIdx, + Formula Base, + unsigned Depth) { + // Arbitrarily cap recursion to protect compile time. + if (Depth >= 3) return; - Formula F = Base; - std::swap(F.BaseRegs[i], F.BaseRegs.back()); - F.BaseRegs.pop_back(); - for (SmallVectorImpl::const_iterator I = AddOps.begin(), - E = AddOps.end(); I != E; ++I) - F.BaseRegs.push_back(*I); - F.AM.HasBaseReg = !F.BaseRegs.empty(); - if (InsertFormula(LU, LUIdx, F)) - // If that formula hadn't been seen before, recurse to find more like it. - GenerateReassociationReuse(LU, LUIdx, LU.Formulae.back()); -} - -/// GenerateReassociationReuse - Split out subexpressions from adds and -/// the bases of addrecs. -void LSRInstance::GenerateReassociationReuse(LSRUse &LU, unsigned LUIdx, - Formula Base) { - SmallVector AddOps; for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) { const SCEV *BaseReg = Base.BaseRegs[i]; - if (const SCEVAddExpr *Add = dyn_cast(BaseReg)) { - for (SCEVAddExpr::op_iterator J = Add->op_begin(), JE = Add->op_end(); - J != JE; ++J) { - // Don't pull a constant into a register if the constant could be - // folded into an immediate field. - if (isAlwaysFoldable(*J, true, LU.Kind, LU.AccessTy, TLI, SE)) continue; - SmallVector InnerAddOps; - for (SCEVAddExpr::op_iterator K = Add->op_begin(); K != JE; ++K) - if (K != J) - InnerAddOps.push_back(*K); - // Splitting a 2-operand add both ways is redundant. Pruning this - // now saves compile time. - if (InnerAddOps.size() < 2 && next(J) == JE) - continue; - AddOps.push_back(*J); - const SCEV *InnerAdd = SE.getAddExpr(InnerAddOps); - AddOps.push_back(InnerAdd); - GenerateFormulaeFromReplacedBaseReg(LU, LUIdx, Base, i, AddOps); - AddOps.clear(); - } - } else if (const SCEVAddRecExpr *AR = dyn_cast(BaseReg)) { - if (const SCEVAddExpr *Add = dyn_cast(AR->getStart())) { - for (SCEVAddExpr::op_iterator J = Add->op_begin(), JE = Add->op_end(); - J != JE; ++J) { - // Don't pull a constant into a register if the constant could be - // folded into an immediate field. - if (isAlwaysFoldable(*J, true, LU.Kind, LU.AccessTy, TLI, SE)) - continue; - SmallVector InnerAddOps; - for (SCEVAddExpr::op_iterator K = Add->op_begin(); K != JE; ++K) - if (K != J) - InnerAddOps.push_back(*K); - AddOps.push_back(*J); - const SCEV *InnerAdd = SE.getAddExpr(InnerAddOps); - AddOps.push_back(SE.getAddRecExpr(InnerAdd, - AR->getStepRecurrence(SE), - AR->getLoop())); - GenerateFormulaeFromReplacedBaseReg(LU, LUIdx, Base, i, AddOps); - AddOps.clear(); - } - } else if (!isAlwaysFoldable(AR->getStart(), Base.BaseRegs.size() > 1, - LU.Kind, LU.AccessTy, - TLI, SE)) { - AddOps.push_back(AR->getStart()); - AddOps.push_back(SE.getAddRecExpr(SE.getIntegerSCEV(0, - BaseReg->getType()), - AR->getStepRecurrence(SE), - AR->getLoop())); - GenerateFormulaeFromReplacedBaseReg(LU, LUIdx, Base, i, AddOps); - AddOps.clear(); - } + + SmallVector AddOps; + CollectSubexprs(BaseReg, 0, AddOps, SE); + if (AddOps.size() == 1) continue; + + for (SmallVectorImpl::const_iterator J = AddOps.begin(), + JE = AddOps.end(); J != JE; ++J) { + // Don't pull a constant into a register if the constant could be folded + // into an immediate field. + if (isAlwaysFoldable(*J, LU.MinOffset, LU.MaxOffset, + Base.getNumRegs() > 1, + LU.Kind, LU.AccessTy, TLI, SE)) + continue; + + // Collect all operands except *J. + SmallVector InnerAddOps; + for (SmallVectorImpl::const_iterator K = AddOps.begin(), + KE = AddOps.end(); K != KE; ++K) + if (K != J) + InnerAddOps.push_back(*K); + + // Don't leave just a constant behind in a register if the constant could + // be folded into an immediate field. + if (InnerAddOps.size() == 1 && + isAlwaysFoldable(InnerAddOps[0], LU.MinOffset, LU.MaxOffset, + Base.getNumRegs() > 1, + LU.Kind, LU.AccessTy, TLI, SE)) + continue; + + Formula F = Base; + F.BaseRegs[i] = SE.getAddExpr(InnerAddOps); + F.BaseRegs.push_back(*J); + if (InsertFormula(LU, LUIdx, F)) + // If that formula hadn't been seen before, recurse to find more like + // it. + GenerateReassociations(LU, LUIdx, LU.Formulae.back(), Depth+1); } } } -/// GenerateCombinationReuse - Generate a formula consisting of all of the +/// GenerateCombinations - Generate a formula consisting of all of the /// loop-dominating registers added into a single register. -void LSRInstance::GenerateCombinationReuse(LSRUse &LU, unsigned LUIdx, - Formula Base) { +void LSRInstance::GenerateCombinations(LSRUse &LU, unsigned LUIdx, + Formula Base) { + // This method is only interesting on a plurality of registers. if (Base.BaseRegs.size() <= 1) return; Formula F = Base; @@ -2116,68 +2051,206 @@ void LSRInstance::GenerateCombinationReuse(LSRUse &LU, unsigned LUIdx, F.BaseRegs.push_back(BaseReg); } if (Ops.size() > 1) { - F.BaseRegs.push_back(SE.getAddExpr(Ops)); - (void)InsertFormula(LU, LUIdx, F); + const SCEV *Sum = SE.getAddExpr(Ops); + // TODO: If Sum is zero, it probably means ScalarEvolution missed an + // opportunity to fold something. For now, just ignore such cases + // rather than proceed with zero in a register. + if (!Sum->isZero()) { + F.BaseRegs.push_back(Sum); + (void)InsertFormula(LU, LUIdx, F); + } + } +} + +/// GenerateSymbolicOffsets - Generate reuse formulae using symbolic offsets. +void LSRInstance::GenerateSymbolicOffsets(LSRUse &LU, unsigned LUIdx, + Formula Base) { + // We can't add a symbolic offset if the address already contains one. + if (Base.AM.BaseGV) return; + + for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) { + const SCEV *G = Base.BaseRegs[i]; + GlobalValue *GV = ExtractSymbol(G, SE); + if (G->isZero() || !GV) + continue; + Formula F = Base; + F.AM.BaseGV = GV; + if (!isLegalUse(F.AM, LU.MinOffset, LU.MaxOffset, + LU.Kind, LU.AccessTy, TLI)) + continue; + F.BaseRegs[i] = G; + (void)InsertFormula(LU, LUIdx, F); + } +} + +/// GenerateConstantOffsets - Generate reuse formulae using symbolic offsets. +void LSRInstance::GenerateConstantOffsets(LSRUse &LU, unsigned LUIdx, + Formula Base) { + // TODO: For now, just add the min and max offset, because it usually isn't + // worthwhile looking at everything inbetween. + SmallVector Worklist; + Worklist.push_back(LU.MinOffset); + if (LU.MaxOffset != LU.MinOffset) + Worklist.push_back(LU.MaxOffset); + + for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) { + const SCEV *G = Base.BaseRegs[i]; + + for (SmallVectorImpl::const_iterator I = Worklist.begin(), + E = Worklist.end(); I != E; ++I) { + Formula F = Base; + F.AM.BaseOffs = (uint64_t)Base.AM.BaseOffs - *I; + if (isLegalUse(F.AM, LU.MinOffset - *I, LU.MaxOffset - *I, + LU.Kind, LU.AccessTy, TLI)) { + F.BaseRegs[i] = SE.getAddExpr(G, SE.getIntegerSCEV(*I, G->getType())); + + (void)InsertFormula(LU, LUIdx, F); + } + } + + int64_t Imm = ExtractImmediate(G, SE); + if (G->isZero() || Imm == 0) + continue; + Formula F = Base; + F.AM.BaseOffs = (uint64_t)F.AM.BaseOffs + Imm; + if (!isLegalUse(F.AM, LU.MinOffset, LU.MaxOffset, + LU.Kind, LU.AccessTy, TLI)) + continue; + F.BaseRegs[i] = G; + (void)InsertFormula(LU, LUIdx, F); } } -/// GenerateScaledReuse - Generate stride factor reuse formulae by making -/// use of scaled-offset address modes, for example. -void LSRInstance::GenerateScaledReuse(LSRUse &LU, unsigned LUIdx, - Formula Base) { +/// GenerateICmpZeroScales - For ICmpZero, check to see if we can scale up +/// the comparison. For example, x == y -> x*c == y*c. +void LSRInstance::GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx, + Formula Base) { + if (LU.Kind != LSRUse::ICmpZero) return; + // Determine the integer type for the base formula. const Type *IntTy = Base.getType(); if (!IntTy) return; - IntTy = SE.getEffectiveSCEVType(IntTy); + if (SE.getTypeSizeInBits(IntTy) > 64) return; + + // Don't do this if there is more than one offset. + if (LU.MinOffset != LU.MaxOffset) return; + + assert(!Base.AM.BaseGV && "ICmpZero use is not legal!"); // Check each interesting stride. - for (SmallSetVector::const_iterator + for (SmallSetVector::const_iterator I = Factors.begin(), E = Factors.end(); I != E; ++I) { int64_t Factor = *I; + Formula F = Base; - // If this Formula already has a scaled register, we can't add another one. - if (Base.AM.Scale != 0) + // Check that the multiplication doesn't overflow. + if (F.AM.BaseOffs == INT64_MIN && Factor == -1) continue; - Formula F = Base; - F.AM.Scale = Factor; + F.AM.BaseOffs = (uint64_t)Base.AM.BaseOffs * Factor; + if (F.AM.BaseOffs / Factor != Base.AM.BaseOffs) + continue; + + // Check that multiplying with the use offset doesn't overflow. + int64_t Offset = LU.MinOffset; + if (Offset == INT64_MIN && Factor == -1) + continue; + Offset = (uint64_t)Offset * Factor; + if (Offset / Factor != LU.MinOffset) + continue; + + // Check that this scale is legal. + if (!isLegalUse(F.AM, Offset, Offset, LU.Kind, LU.AccessTy, TLI)) + continue; + + // Compensate for the use having MinOffset built into it. + F.AM.BaseOffs = (uint64_t)F.AM.BaseOffs + Offset - LU.MinOffset; + + const SCEV *FactorS = SE.getIntegerSCEV(Factor, IntTy); + + // Check that multiplying with each base register doesn't overflow. + for (size_t i = 0, e = F.BaseRegs.size(); i != e; ++i) { + F.BaseRegs[i] = SE.getMulExpr(F.BaseRegs[i], FactorS); + if (getExactSDiv(F.BaseRegs[i], FactorS, SE) != Base.BaseRegs[i]) + goto next; + } + + // Check that multiplying with the scaled register doesn't overflow. + if (F.ScaledReg) { + F.ScaledReg = SE.getMulExpr(F.ScaledReg, FactorS); + if (getExactSDiv(F.ScaledReg, FactorS, SE) != Base.ScaledReg) + continue; + } + + // If we make it here and it's legal, add it. + (void)InsertFormula(LU, LUIdx, F); + next:; + } +} + +/// GenerateScales - Generate stride factor reuse formulae by making use of +/// scaled-offset address modes, for example. +void LSRInstance::GenerateScales(LSRUse &LU, unsigned LUIdx, + Formula Base) { + // Determine the integer type for the base formula. + const Type *IntTy = Base.getType(); + if (!IntTy) return; + + // If this Formula already has a scaled register, we can't add another one. + if (Base.AM.Scale != 0) return; + + // Check each interesting stride. + for (SmallSetVector::const_iterator + I = Factors.begin(), E = Factors.end(); I != E; ++I) { + int64_t Factor = *I; + + Base.AM.Scale = Factor; + Base.AM.HasBaseReg = Base.BaseRegs.size() > 1; // Check whether this scale is going to be legal. - if (!isLegalUse(F.AM, LU.Kind, LU.AccessTy, TLI)) { + if (!isLegalUse(Base.AM, LU.MinOffset, LU.MaxOffset, + LU.Kind, LU.AccessTy, TLI)) { // As a special-case, handle special out-of-loop Basic users specially. // TODO: Reconsider this special case. if (LU.Kind == LSRUse::Basic && - isLegalUse(F.AM, LSRUse::Special, LU.AccessTy, TLI) && - !L->contains(LU.UserInst)) + isLegalUse(Base.AM, LU.MinOffset, LU.MaxOffset, + LSRUse::Special, LU.AccessTy, TLI) && + LU.AllFixupsOutsideLoop) LU.Kind = LSRUse::Special; else continue; } + // For an ICmpZero, negating a solitary base register won't lead to + // new solutions. + if (LU.Kind == LSRUse::ICmpZero && + !Base.AM.HasBaseReg && Base.AM.BaseOffs == 0 && !Base.AM.BaseGV) + continue; // For each addrec base reg, apply the scale, if possible. for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) if (const SCEVAddRecExpr *AR = dyn_cast(Base.BaseRegs[i])) { - const SCEV *FactorS = SE.getSCEV(ConstantInt::get(IntTy, Factor)); + const SCEV *FactorS = SE.getIntegerSCEV(Factor, IntTy); + if (FactorS->isZero()) + continue; // Divide out the factor, ignoring high bits, since we'll be // scaling the value back up in the end. - if (const SCEV *Quotient = getSDiv(AR, FactorS, SE, true)) { + if (const SCEV *Quotient = getExactSDiv(AR, FactorS, SE, true)) { // TODO: This could be optimized to avoid all the copying. - Formula NewF = F; - NewF.ScaledReg = Quotient; - std::swap(NewF.BaseRegs[i], NewF.BaseRegs.back()); - NewF.BaseRegs.pop_back(); - NewF.AM.HasBaseReg = !NewF.BaseRegs.empty(); - (void)InsertFormula(LU, LUIdx, NewF); + Formula F = Base; + F.ScaledReg = Quotient; + std::swap(F.BaseRegs[i], F.BaseRegs.back()); + F.BaseRegs.pop_back(); + (void)InsertFormula(LU, LUIdx, F); } } } } -/// GenerateTruncateReuse - Generate reuse formulae from different IV types. -void LSRInstance::GenerateTruncateReuse(LSRUse &LU, unsigned LUIdx, - Formula Base) { +/// GenerateTruncates - Generate reuse formulae from different IV types. +void LSRInstance::GenerateTruncates(LSRUse &LU, unsigned LUIdx, + Formula Base) { // This requires TargetLowering to tell us which truncates are free. if (!TLI) return; - // Don't attempt to truncate symbolic values. + // Don't bother truncating symbolic values. if (Base.AM.BaseGV) return; // Determine the integer type for the base formula. @@ -2190,10 +2263,17 @@ void LSRInstance::GenerateTruncateReuse(LSRUse &LU, unsigned LUIdx, const Type *SrcTy = *I; if (SrcTy != DstTy && TLI->isTruncateFree(SrcTy, DstTy)) { Formula F = Base; + if (F.ScaledReg) F.ScaledReg = SE.getAnyExtendExpr(F.ScaledReg, *I); for (SmallVectorImpl::iterator J = F.BaseRegs.begin(), JE = F.BaseRegs.end(); J != JE; ++J) *J = SE.getAnyExtendExpr(*J, SrcTy); + + // TODO: This assumes we've done basic processing on all uses and + // have an idea what the register usage is. + if (!F.hasRegsUsedByUsesOtherThan(LUIdx, RegUses)) + continue; + (void)InsertFormula(LU, LUIdx, F); } } @@ -2201,45 +2281,43 @@ void LSRInstance::GenerateTruncateReuse(LSRUse &LU, unsigned LUIdx, namespace { -/// WorkItem - Helper class for GenerateConstantOffsetReuse. It's used to +/// WorkItem - Helper class for GenerateCrossUseConstantOffsets. It's used to /// defer modifications so that the search phase doesn't have to worry about /// the data structures moving underneath it. struct WorkItem { - LSRUse *LU; size_t LUIdx; int64_t Imm; const SCEV *OrigReg; - WorkItem(LSRUse *U, size_t LI, int64_t I, const SCEV *R) - : LU(U), LUIdx(LI), Imm(I), OrigReg(R) {} + WorkItem(size_t LI, int64_t I, const SCEV *R) + : LUIdx(LI), Imm(I), OrigReg(R) {} void print(raw_ostream &OS) const; void dump() const; }; +} + void WorkItem::print(raw_ostream &OS) const { - OS << "in use "; - LU->print(OS); - OS << " (at index " << LUIdx << "), add offset " << Imm - << " and compensate by adjusting refences to " << *OrigReg << "\n"; + OS << "in formulae referencing " << *OrigReg << " in use " << LUIdx + << " , add offset " << Imm; } void WorkItem::dump() const { print(errs()); errs() << '\n'; } -} - -/// GenerateConstantOffsetReuse - Look for registers which are a constant +/// GenerateCrossUseConstantOffsets - Look for registers which are a constant /// distance apart and try to form reuse opportunities between them. -void LSRInstance::GenerateConstantOffsetReuse() { +void LSRInstance::GenerateCrossUseConstantOffsets() { // Group the registers by their value without any added constant offset. typedef std::map ImmMapTy; typedef DenseMap RegMapTy; RegMapTy Map; + DenseMap UsedByIndicesMap; SmallVector Sequence; - for (SmallVectorImpl::iterator I = RegSequence.begin(), - E = RegSequence.end(); I != E; ++I) { + for (RegUseTracker::const_iterator I = RegUses.begin(), E = RegUses.end(); + I != E; ++I) { const SCEV *Reg = *I; int64_t Imm = ExtractImmediate(Reg, SE); std::pair Pair = @@ -2247,467 +2325,846 @@ void LSRInstance::GenerateConstantOffsetReuse() { if (Pair.second) Sequence.push_back(Reg); Pair.first->second.insert(std::make_pair(Imm, *I)); + UsedByIndicesMap[Reg] |= RegUses.getUsedByIndices(*I); } - // Insert an artificial expression at offset 0 (if there isn't one already), - // as this may lead to more reuse opportunities. - for (SmallVectorImpl::const_iterator I = Sequence.begin(), - E = Sequence.end(); I != E; ++I) - Map.find(*I)->second.insert(ImmMapTy::value_type(0, 0)); - // Now examine each set of registers with the same base value. Build up // a list of work to do and do the work in a separate step so that we're // not adding formulae and register counts while we're searching. SmallVector WorkItems; + SmallSet, 32> UniqueItems; for (SmallVectorImpl::const_iterator I = Sequence.begin(), E = Sequence.end(); I != E; ++I) { const SCEV *Reg = *I; const ImmMapTy &Imms = Map.find(Reg)->second; + + // It's not worthwhile looking for reuse if there's only one offset. + if (Imms.size() == 1) + continue; + + DEBUG(dbgs() << "Generating cross-use offsets for " << *Reg << ':'; + for (ImmMapTy::const_iterator J = Imms.begin(), JE = Imms.end(); + J != JE; ++J) + dbgs() << ' ' << J->first; + dbgs() << '\n'); + // Examine each offset. for (ImmMapTy::const_iterator J = Imms.begin(), JE = Imms.end(); J != JE; ++J) { const SCEV *OrigReg = J->second; - // Skip the artifical register at offset 0. - if (!OrigReg) continue; - int64_t JImm = J->first; - const SmallBitVector &Bits = RegUses.find(OrigReg)->second.Bits; + int64_t JImm = J->first; + const SmallBitVector &UsedByIndices = RegUses.getUsedByIndices(OrigReg); + + if (!isa(OrigReg) && + UsedByIndicesMap[Reg].count() == 1) { + DEBUG(dbgs() << "Skipping cross-use reuse for " << *OrigReg << '\n'); + continue; + } + + // Conservatively examine offsets between this orig reg a few selected + // other orig regs. + ImmMapTy::const_iterator OtherImms[] = { + Imms.begin(), prior(Imms.end()), + Imms.upper_bound((Imms.begin()->first + prior(Imms.end())->first) / 2) + }; + for (size_t i = 0, e = array_lengthof(OtherImms); i != e; ++i) { + ImmMapTy::const_iterator M = OtherImms[i]; + if (M == J || M == JE) continue; + + // Compute the difference between the two. + int64_t Imm = (uint64_t)JImm - M->first; + for (int LUIdx = UsedByIndices.find_first(); LUIdx != -1; + LUIdx = UsedByIndices.find_next(LUIdx)) + // Make a memo of this use, offset, and register tuple. + if (UniqueItems.insert(std::make_pair(LUIdx, Imm))) + WorkItems.push_back(WorkItem(LUIdx, Imm, OrigReg)); + } + } + } + + Map.clear(); + Sequence.clear(); + UsedByIndicesMap.clear(); + UniqueItems.clear(); + + // Now iterate through the worklist and add new formulae. + for (SmallVectorImpl::const_iterator I = WorkItems.begin(), + E = WorkItems.end(); I != E; ++I) { + const WorkItem &WI = *I; + size_t LUIdx = WI.LUIdx; + LSRUse &LU = Uses[LUIdx]; + int64_t Imm = WI.Imm; + const SCEV *OrigReg = WI.OrigReg; + + const Type *IntTy = SE.getEffectiveSCEVType(OrigReg->getType()); + const SCEV *NegImmS = SE.getSCEV(ConstantInt::get(IntTy, -(uint64_t)Imm)); + unsigned BitWidth = SE.getTypeSizeInBits(IntTy); + + // TODO: Use a more targeted data structure. + for (size_t L = 0, LE = LU.Formulae.size(); L != LE; ++L) { + Formula F = LU.Formulae[L]; + // Use the immediate in the scaled register. + if (F.ScaledReg == OrigReg) { + int64_t Offs = (uint64_t)F.AM.BaseOffs + + Imm * (uint64_t)F.AM.Scale; + // Don't create 50 + reg(-50). + if (F.referencesReg(SE.getSCEV( + ConstantInt::get(IntTy, -(uint64_t)Offs)))) + continue; + Formula NewF = F; + NewF.AM.BaseOffs = Offs; + if (!isLegalUse(NewF.AM, LU.MinOffset, LU.MaxOffset, + LU.Kind, LU.AccessTy, TLI)) + continue; + NewF.ScaledReg = SE.getAddExpr(NegImmS, NewF.ScaledReg); + + // If the new scale is a constant in a register, and adding the constant + // value to the immediate would produce a value closer to zero than the + // immediate itself, then the formula isn't worthwhile. + if (const SCEVConstant *C = dyn_cast(NewF.ScaledReg)) + if (C->getValue()->getValue().isNegative() != + (NewF.AM.BaseOffs < 0) && + (C->getValue()->getValue().abs() * APInt(BitWidth, F.AM.Scale)) + .ule(APInt(BitWidth, NewF.AM.BaseOffs).abs())) + continue; + + // OK, looks good. + (void)InsertFormula(LU, LUIdx, NewF); + } else { + // Use the immediate in a base register. + for (size_t N = 0, NE = F.BaseRegs.size(); N != NE; ++N) { + const SCEV *BaseReg = F.BaseRegs[N]; + if (BaseReg != OrigReg) + continue; + Formula NewF = F; + NewF.AM.BaseOffs = (uint64_t)NewF.AM.BaseOffs + Imm; + if (!isLegalUse(NewF.AM, LU.MinOffset, LU.MaxOffset, + LU.Kind, LU.AccessTy, TLI)) + continue; + NewF.BaseRegs[N] = SE.getAddExpr(NegImmS, BaseReg); + + // If the new formula has a constant in a register, and adding the + // constant value to the immediate would produce a value closer to + // zero than the immediate itself, then the formula isn't worthwhile. + for (SmallVectorImpl::const_iterator + J = NewF.BaseRegs.begin(), JE = NewF.BaseRegs.end(); + J != JE; ++J) + if (const SCEVConstant *C = dyn_cast(*J)) + if (C->getValue()->getValue().isNegative() != + (NewF.AM.BaseOffs < 0) && + C->getValue()->getValue().abs() + .ule(APInt(BitWidth, NewF.AM.BaseOffs).abs())) + goto skip_formula; + + // Ok, looks good. + (void)InsertFormula(LU, LUIdx, NewF); + break; + skip_formula:; + } + } + } + } +} + +/// GenerateAllReuseFormulae - Generate formulae for each use. +void +LSRInstance::GenerateAllReuseFormulae() { + // This is split into multiple loops so that hasRegsUsedByUsesOtherThan + // queries are more precise. + for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { + LSRUse &LU = Uses[LUIdx]; + for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) + GenerateReassociations(LU, LUIdx, LU.Formulae[i]); + for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) + GenerateCombinations(LU, LUIdx, LU.Formulae[i]); + } + for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { + LSRUse &LU = Uses[LUIdx]; + for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) + GenerateSymbolicOffsets(LU, LUIdx, LU.Formulae[i]); + for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) + GenerateConstantOffsets(LU, LUIdx, LU.Formulae[i]); + for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) + GenerateICmpZeroScales(LU, LUIdx, LU.Formulae[i]); + for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) + GenerateScales(LU, LUIdx, LU.Formulae[i]); + } + for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { + LSRUse &LU = Uses[LUIdx]; + for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) + GenerateTruncates(LU, LUIdx, LU.Formulae[i]); + } + + GenerateCrossUseConstantOffsets(); +} + +/// If their are multiple formulae with the same set of registers used +/// by other uses, pick the best one and delete the others. +void LSRInstance::FilterOutUndesirableDedicatedRegisters() { +#ifndef NDEBUG + bool Changed = false; +#endif + + // Collect the best formula for each unique set of shared registers. This + // is reset for each use. + typedef DenseMap, size_t, UniquifierDenseMapInfo> + BestFormulaeTy; + BestFormulaeTy BestFormulae; + + for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { + LSRUse &LU = Uses[LUIdx]; + FormulaSorter Sorter(L, LU, SE, DT); + + // Clear out the set of used regs; it will be recomputed. + LU.Regs.clear(); + + for (size_t FIdx = 0, NumForms = LU.Formulae.size(); + FIdx != NumForms; ++FIdx) { + Formula &F = LU.Formulae[FIdx]; + + SmallVector Key; + for (SmallVectorImpl::const_iterator J = F.BaseRegs.begin(), + JE = F.BaseRegs.end(); J != JE; ++J) { + const SCEV *Reg = *J; + if (RegUses.isRegUsedByUsesOtherThan(Reg, LUIdx)) + Key.push_back(Reg); + } + if (F.ScaledReg && + RegUses.isRegUsedByUsesOtherThan(F.ScaledReg, LUIdx)) + Key.push_back(F.ScaledReg); + // Unstable sort by host order ok, because this is only used for + // uniquifying. + std::sort(Key.begin(), Key.end()); + + std::pair P = + BestFormulae.insert(std::make_pair(Key, FIdx)); + if (!P.second) { + Formula &Best = LU.Formulae[P.first->second]; + if (Sorter.operator()(F, Best)) + std::swap(F, Best); + DEBUG(dbgs() << "Filtering out "; F.print(dbgs()); + dbgs() << "\n" + " in favor of "; Best.print(dbgs()); + dbgs() << '\n'); +#ifndef NDEBUG + Changed = true; +#endif + std::swap(F, LU.Formulae.back()); + LU.Formulae.pop_back(); + --FIdx; + --NumForms; + continue; + } + if (F.ScaledReg) LU.Regs.insert(F.ScaledReg); + LU.Regs.insert(F.BaseRegs.begin(), F.BaseRegs.end()); + } + BestFormulae.clear(); + } + + DEBUG(if (Changed) { + dbgs() << "\n" + "After filtering out undesirable candidates:\n"; + print_uses(dbgs()); + }); +} + +/// NarrowSearchSpaceUsingHeuristics - If there are an extraordinary number of +/// formulae to choose from, use some rough heuristics to prune down the number +/// of formulae. This keeps the main solver from taking an extraordinary amount +/// of time in some worst-case scenarios. +void LSRInstance::NarrowSearchSpaceUsingHeuristics() { + // This is a rough guess that seems to work fairly well. + const size_t Limit = UINT16_MAX; + + SmallPtrSet Taken; + for (;;) { + // Estimate the worst-case number of solutions we might consider. We almost + // never consider this many solutions because we prune the search space, + // but the pruning isn't always sufficient. + uint32_t Power = 1; + for (SmallVectorImpl::const_iterator I = Uses.begin(), + E = Uses.end(); I != E; ++I) { + size_t FSize = I->Formulae.size(); + if (FSize >= Limit) { + Power = Limit; + break; + } + Power *= FSize; + if (Power >= Limit) + break; + } + if (Power < Limit) + break; + + // Ok, we have too many of formulae on our hands to conveniently handle. + // Use a rough heuristic to thin out the list. + + // Pick the register which is used by the most LSRUses, which is likely + // to be a good reuse register candidate. + const SCEV *Best = 0; + unsigned BestNum = 0; + for (RegUseTracker::const_iterator I = RegUses.begin(), E = RegUses.end(); + I != E; ++I) { + const SCEV *Reg = *I; + if (Taken.count(Reg)) + continue; + if (!Best) + Best = Reg; + else { + unsigned Count = RegUses.getUsedByIndices(Reg).count(); + if (Count > BestNum) { + Best = Reg; + BestNum = Count; + } + } + } + + DEBUG(dbgs() << "Narrowing the search space by assuming " << *Best + << " will yield profitable reuse.\n"); + Taken.insert(Best); + + // In any use with formulae which references this register, delete formulae + // which don't reference it. + for (SmallVectorImpl::iterator I = Uses.begin(), + E = Uses.end(); I != E; ++I) { + LSRUse &LU = *I; + if (!LU.Regs.count(Best)) continue; + + // Clear out the set of used regs; it will be recomputed. + LU.Regs.clear(); + + for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) { + Formula &F = LU.Formulae[i]; + if (!F.referencesReg(Best)) { + DEBUG(dbgs() << " Deleting "; F.print(dbgs()); dbgs() << '\n'); + std::swap(LU.Formulae.back(), F); + LU.Formulae.pop_back(); + --e; + --i; + continue; + } + + if (F.ScaledReg) LU.Regs.insert(F.ScaledReg); + LU.Regs.insert(F.BaseRegs.begin(), F.BaseRegs.end()); + } + } + + DEBUG(dbgs() << "After pre-selection:\n"; + print_uses(dbgs())); + } +} + +/// SolveRecurse - This is the recursive solver. +void LSRInstance::SolveRecurse(SmallVectorImpl &Solution, + Cost &SolutionCost, + SmallVectorImpl &Workspace, + const Cost &CurCost, + const SmallPtrSet &CurRegs, + DenseSet &VisitedRegs) const { + // Some ideas: + // - prune more: + // - use more aggressive filtering + // - sort the formula so that the most profitable solutions are found first + // - sort the uses too + // - search faster: + // - don't compute a cost, and then compare. compare while computing a cost + // and bail early. + // - track register sets with SmallBitVector + + const LSRUse &LU = Uses[Workspace.size()]; + + // If this use references any register that's already a part of the + // in-progress solution, consider it a requirement that a formula must + // reference that register in order to be considered. This prunes out + // unprofitable searching. + SmallSetVector ReqRegs; + for (SmallPtrSet::const_iterator I = CurRegs.begin(), + E = CurRegs.end(); I != E; ++I) + if (LU.Regs.count(*I)) + ReqRegs.insert(*I); + + bool AnySatisfiedReqRegs = false; + SmallPtrSet NewRegs; + Cost NewCost; +retry: + for (SmallVectorImpl::const_iterator I = LU.Formulae.begin(), + E = LU.Formulae.end(); I != E; ++I) { + const Formula &F = *I; + + // Ignore formulae which do not use any of the required registers. + for (SmallSetVector::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) == + F.BaseRegs.end()) + goto skip; + } + AnySatisfiedReqRegs = true; + + // Evaluate the cost of the current formula. If it's already worse than + // the current best, prune the search at that point. + NewCost = CurCost; + NewRegs = CurRegs; + NewCost.RateFormula(F, NewRegs, VisitedRegs, L, LU.Offsets, SE, DT); + if (NewCost < SolutionCost) { + Workspace.push_back(&F); + if (Workspace.size() != Uses.size()) { + SolveRecurse(Solution, SolutionCost, Workspace, NewCost, + NewRegs, VisitedRegs); + if (F.getNumRegs() == 1 && Workspace.size() == 1) + VisitedRegs.insert(F.ScaledReg ? F.ScaledReg : F.BaseRegs[0]); + } else { + DEBUG(dbgs() << "New best at "; NewCost.print(dbgs()); + dbgs() << ". Regs:"; + for (SmallPtrSet::const_iterator + I = NewRegs.begin(), E = NewRegs.end(); I != E; ++I) + dbgs() << ' ' << **I; + dbgs() << '\n'); + + SolutionCost = NewCost; + Solution = Workspace; + } + Workspace.pop_back(); + } + skip:; + } + + // If none of the formulae had all of the required registers, relax the + // constraint so that we don't exclude all formulae. + if (!AnySatisfiedReqRegs) { + ReqRegs.clear(); + goto retry; + } +} + +void LSRInstance::Solve(SmallVectorImpl &Solution) const { + SmallVector Workspace; + Cost SolutionCost; + SolutionCost.Loose(); + Cost CurCost; + SmallPtrSet CurRegs; + DenseSet VisitedRegs; + Workspace.reserve(Uses.size()); + + SolveRecurse(Solution, SolutionCost, Workspace, CurCost, + CurRegs, VisitedRegs); + + // Ok, we've now made all our decisions. + DEBUG(dbgs() << "\n" + "The chosen solution requires "; SolutionCost.print(dbgs()); + dbgs() << ":\n"; + for (size_t i = 0, e = Uses.size(); i != e; ++i) { + dbgs() << " "; + Uses[i].print(dbgs()); + dbgs() << "\n" + " "; + Solution[i]->print(dbgs()); + dbgs() << '\n'; + }); +} + +/// getImmediateDominator - A handy utility for the specific DominatorTree +/// query that we need here. +/// +static BasicBlock *getImmediateDominator(BasicBlock *BB, DominatorTree &DT) { + DomTreeNode *Node = DT.getNode(BB); + if (!Node) return 0; + Node = Node->getIDom(); + if (!Node) return 0; + return Node->getBlock(); +} + +Value *LSRInstance::Expand(const LSRFixup &LF, + const Formula &F, + BasicBlock::iterator IP, + SCEVExpander &Rewriter, + SmallVectorImpl &DeadInsts) const { + const LSRUse &LU = Uses[LF.LUIdx]; + + // Then, collect some instructions which we will remain dominated by when + // expanding the replacement. These must be dominated by any operands that + // will be required in the expansion. + SmallVector Inputs; + if (Instruction *I = dyn_cast(LF.OperandValToReplace)) + Inputs.push_back(I); + if (LU.Kind == LSRUse::ICmpZero) + if (Instruction *I = + dyn_cast(cast(LF.UserInst)->getOperand(1))) + Inputs.push_back(I); + if (LF.PostIncLoop) { + if (!L->contains(LF.UserInst)) + Inputs.push_back(L->getLoopLatch()->getTerminator()); + else + Inputs.push_back(IVIncInsertPos); + } + + // Then, climb up the immediate dominator tree as far as we can go while + // still being dominated by the input positions. + for (;;) { + bool AllDominate = true; + Instruction *BetterPos = 0; + BasicBlock *IDom = getImmediateDominator(IP->getParent(), DT); + if (!IDom) break; + Instruction *Tentative = IDom->getTerminator(); + for (SmallVectorImpl::const_iterator I = Inputs.begin(), + E = Inputs.end(); I != E; ++I) { + Instruction *Inst = *I; + if (Inst == Tentative || !DT.dominates(Inst, Tentative)) { + AllDominate = false; + break; + } + if (IDom == Inst->getParent() && + (!BetterPos || DT.dominates(BetterPos, Inst))) + BetterPos = next(BasicBlock::iterator(Inst)); + } + if (!AllDominate) + break; + if (BetterPos) + IP = BetterPos; + else + IP = Tentative; + } + while (isa(IP)) ++IP; + + // Inform the Rewriter if we have a post-increment use, so that it can + // perform an advantageous expansion. + Rewriter.setPostInc(LF.PostIncLoop); + + // This is the type that the user actually needs. + const Type *OpTy = LF.OperandValToReplace->getType(); + // This will be the type that we'll initially expand to. + const Type *Ty = F.getType(); + if (!Ty) + // No type known; just expand directly to the ultimate type. + Ty = OpTy; + else if (SE.getEffectiveSCEVType(Ty) == SE.getEffectiveSCEVType(OpTy)) + // Expand directly to the ultimate type if it's the right size. + Ty = OpTy; + // This is the type to do integer arithmetic in. + const Type *IntTy = SE.getEffectiveSCEVType(Ty); + + // Build up a list of operands to add together to form the full base. + SmallVector Ops; + + // Expand the BaseRegs portion. + for (SmallVectorImpl::const_iterator I = F.BaseRegs.begin(), + E = F.BaseRegs.end(); I != E; ++I) { + const SCEV *Reg = *I; + assert(!Reg->isZero() && "Zero allocated in a base register!"); + + // If we're expanding for a post-inc user for the add-rec's loop, make the + // post-inc adjustment. + const SCEV *Start = Reg; + while (const SCEVAddRecExpr *AR = dyn_cast(Start)) { + if (AR->getLoop() == LF.PostIncLoop) { + Reg = SE.getAddExpr(Reg, AR->getStepRecurrence(SE)); + // If the user is inside the loop, insert the code after the increment + // so that it is dominated by its operand. If the original insert point + // was already dominated by the increment, keep it, because there may + // be loop-variant operands that need to be respected also. + if (L->contains(LF.UserInst) && !DT.dominates(IVIncInsertPos, IP)) + IP = IVIncInsertPos; + break; + } + Start = AR->getStart(); + } + + Ops.push_back(SE.getUnknown(Rewriter.expandCodeFor(Reg, 0, IP))); + } + + // Expand the ScaledReg portion. + Value *ICmpScaledV = 0; + if (F.AM.Scale != 0) { + const SCEV *ScaledS = F.ScaledReg; + + // If we're expanding for a post-inc user for the add-rec's loop, make the + // post-inc adjustment. + if (const SCEVAddRecExpr *AR = dyn_cast(ScaledS)) + if (AR->getLoop() == LF.PostIncLoop) + ScaledS = SE.getAddExpr(ScaledS, AR->getStepRecurrence(SE)); + + if (LU.Kind == LSRUse::ICmpZero) { + // An interesting way of "folding" with an icmp is to use a negated + // scale, which we'll implement by inserting it into the other operand + // of the icmp. + assert(F.AM.Scale == -1 && + "The only scale supported by ICmpZero uses is -1!"); + ICmpScaledV = Rewriter.expandCodeFor(ScaledS, 0, IP); + } else { + // Otherwise just expand the scaled register and an explicit scale, + // which is expected to be matched as part of the address. + ScaledS = SE.getUnknown(Rewriter.expandCodeFor(ScaledS, 0, IP)); + ScaledS = SE.getMulExpr(ScaledS, + SE.getIntegerSCEV(F.AM.Scale, + ScaledS->getType())); + Ops.push_back(ScaledS); + } + } + + // Expand the immediate portions. + if (F.AM.BaseGV) + Ops.push_back(SE.getSCEV(F.AM.BaseGV)); + int64_t Offset = (uint64_t)F.AM.BaseOffs + LF.Offset; + if (Offset != 0) { + if (LU.Kind == LSRUse::ICmpZero) { + // The other interesting way of "folding" with an ICmpZero is to use a + // negated immediate. + if (!ICmpScaledV) + ICmpScaledV = ConstantInt::get(IntTy, -Offset); + else { + Ops.push_back(SE.getUnknown(ICmpScaledV)); + ICmpScaledV = ConstantInt::get(IntTy, Offset); + } + } else { + // Just add the immediate values. These again are expected to be matched + // as part of the address. + Ops.push_back(SE.getIntegerSCEV(Offset, IntTy)); + } + } + + // Emit instructions summing all the operands. + const SCEV *FullS = Ops.empty() ? + SE.getIntegerSCEV(0, IntTy) : + SE.getAddExpr(Ops); + Value *FullV = Rewriter.expandCodeFor(FullS, Ty, IP); - // Examine each other offset associated with the same register. This is - // quadradic in the number of registers with the same base, but it's - // uncommon for this to be a large number. - for (ImmMapTy::const_iterator M = Imms.begin(); M != JE; ++M) { - if (M == J) continue; + // We're done expanding now, so reset the rewriter. + Rewriter.setPostInc(0); - // Compute the difference between the two. - int64_t Imm = (uint64_t)JImm - M->first; - for (int LUIdx = Bits.find_first(); LUIdx != -1; - LUIdx = Bits.find_next(LUIdx)) - // Make a memo of this use, offset, and register tuple. - WorkItems.push_back(WorkItem(&Uses[LUIdx], LUIdx, Imm, OrigReg)); + // An ICmpZero Formula represents an ICmp which we're handling as a + // comparison against zero. Now that we've expanded an expression for that + // form, update the ICmp's other operand. + if (LU.Kind == LSRUse::ICmpZero) { + ICmpInst *CI = cast(LF.UserInst); + DeadInsts.push_back(CI->getOperand(1)); + assert(!F.AM.BaseGV && "ICmp does not support folding a global value and " + "a scale at the same time!"); + if (F.AM.Scale == -1) { + if (ICmpScaledV->getType() != OpTy) { + Instruction *Cast = + CastInst::Create(CastInst::getCastOpcode(ICmpScaledV, false, + OpTy, false), + ICmpScaledV, OpTy, "tmp", CI); + ICmpScaledV = Cast; } + CI->setOperand(1, ICmpScaledV); + } else { + assert(F.AM.Scale == 0 && + "ICmp does not support folding a global value and " + "a scale at the same time!"); + Constant *C = ConstantInt::getSigned(SE.getEffectiveSCEVType(OpTy), + -(uint64_t)Offset); + if (C->getType() != OpTy) + C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, + OpTy, false), + C, OpTy); + + CI->setOperand(1, C); } } - // Now iterate through the worklist and add new formulae. - for (SmallVectorImpl::const_iterator I = WorkItems.begin(), - E = WorkItems.end(); I != E; ++I) { - const WorkItem &WI = *I; - LSRUse &LU = *WI.LU; - size_t LUIdx = WI.LUIdx; - int64_t Imm = WI.Imm; - const SCEV *OrigReg = WI.OrigReg; - - const Type *IntTy = SE.getEffectiveSCEVType(OrigReg->getType()); - const SCEV *NegImmS = SE.getSCEV(ConstantInt::get(IntTy, - -(uint64_t)Imm)); + return FullV; +} - for (size_t L = 0, LE = LU.Formulae.size(); L != LE; ++L) { - Formula F = LU.Formulae[L]; - // Use the immediate in the scaled register. - if (F.ScaledReg == OrigReg) { - int64_t Offs = (uint64_t)F.AM.BaseOffs + - Imm * (uint64_t)F.AM.Scale; - // Don't create 50 + reg(-50). - if (F.referencesReg(SE.getSCEV( - ConstantInt::get(IntTy, -(uint64_t)Offs)))) - continue; - Formula NewF = F; - NewF.AM.BaseOffs = Offs; - if (!isLegalUse(NewF.AM, LU.Kind, LU.AccessTy, TLI)) - continue; - const SCEV *Diff = SE.getAddExpr(NegImmS, NewF.ScaledReg); - if (Diff->isZero()) continue; - NewF.ScaledReg = Diff; - (void)InsertFormula(LU, LUIdx, NewF); +/// RewriteForPHI - Helper for Rewrite. PHI nodes are special because the use +/// of their operands effectively happens in their predecessor blocks, so the +/// expression may need to be expanded in multiple places. +void LSRInstance::RewriteForPHI(PHINode *PN, + const LSRFixup &LF, + const Formula &F, + SCEVExpander &Rewriter, + SmallVectorImpl &DeadInsts, + Pass *P) const { + DenseMap Inserted; + for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) + if (PN->getIncomingValue(i) == LF.OperandValToReplace) { + BasicBlock *BB = PN->getIncomingBlock(i); + + // If this is a critical edge, split the edge so that we do not insert + // the code on all predecessor/successor paths. We do this unless this + // is the canonical backedge for this loop, which complicates post-inc + // users. + if (e != 1 && BB->getTerminator()->getNumSuccessors() > 1 && + !isa(BB->getTerminator()) && + (PN->getParent() != L->getHeader() || !L->contains(BB))) { + // Split the critical edge. + BasicBlock *NewBB = SplitCriticalEdge(BB, PN->getParent(), P); + + // If PN is outside of the loop and BB is in the loop, we want to + // move the block to be immediately before the PHI block, not + // immediately after BB. + if (L->contains(BB) && !L->contains(PN)) + NewBB->moveBefore(PN->getParent()); + + // Splitting the edge can reduce the number of PHI entries we have. + e = PN->getNumIncomingValues(); + BB = NewBB; + i = PN->getBasicBlockIndex(BB); } - // Use the immediate in a base register. - for (size_t N = 0, NE = F.BaseRegs.size(); N != NE; ++N) { - const SCEV *BaseReg = F.BaseRegs[N]; - if (BaseReg != OrigReg) - continue; - Formula NewF = F; - NewF.AM.BaseOffs = (uint64_t)NewF.AM.BaseOffs + Imm; - if (!isLegalUse(NewF.AM, LU.Kind, LU.AccessTy, TLI)) - continue; - const SCEV *Diff = SE.getAddExpr(NegImmS, BaseReg); - if (Diff->isZero()) continue; - // Don't create 50 + reg(-50). - if (Diff == - SE.getSCEV(ConstantInt::get(IntTy, - -(uint64_t)NewF.AM.BaseOffs))) - continue; - NewF.BaseRegs[N] = Diff; - (void)InsertFormula(LU, LUIdx, NewF); + + std::pair::iterator, bool> Pair = + Inserted.insert(std::make_pair(BB, static_cast(0))); + if (!Pair.second) + PN->setIncomingValue(i, Pair.first->second); + else { + Value *FullV = Expand(LF, F, BB->getTerminator(), Rewriter, DeadInsts); + + // If this is reuse-by-noop-cast, insert the noop cast. + const Type *OpTy = LF.OperandValToReplace->getType(); + if (FullV->getType() != OpTy) + FullV = + CastInst::Create(CastInst::getCastOpcode(FullV, false, + OpTy, false), + FullV, LF.OperandValToReplace->getType(), + "tmp", BB->getTerminator()); + + PN->setIncomingValue(i, FullV); + Pair.first->second = FullV; } } - } } -/// GenerateAllReuseFormulae - Generate formulae for each use. -void -LSRInstance::GenerateAllReuseFormulae() { - SmallVector Save; - for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) { - LSRUse &LU = Uses[LUIdx]; +/// Rewrite - Emit instructions for the leading candidate expression for this +/// LSRUse (this is called "expanding"), and update the UserInst to reference +/// the newly expanded value. +void LSRInstance::Rewrite(const LSRFixup &LF, + const Formula &F, + SCEVExpander &Rewriter, + SmallVectorImpl &DeadInsts, + Pass *P) const { + // First, find an insertion point that dominates UserInst. For PHI nodes, + // find the nearest block which dominates all the relevant uses. + if (PHINode *PN = dyn_cast(LF.UserInst)) { + RewriteForPHI(PN, LF, F, Rewriter, DeadInsts, P); + } else { + Value *FullV = Expand(LF, F, LF.UserInst, Rewriter, DeadInsts); - for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) - GenerateSymbolicOffsetReuse(LU, LUIdx, LU.Formulae[i]); - for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) - GenerateICmpZeroScaledReuse(LU, LUIdx, LU.Formulae[i]); - for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) - GenerateReassociationReuse(LU, LUIdx, LU.Formulae[i]); - for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) - GenerateCombinationReuse(LU, LUIdx, LU.Formulae[i]); - for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) - GenerateScaledReuse(LU, LUIdx, LU.Formulae[i]); - for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i) - GenerateTruncateReuse(LU, LUIdx, LU.Formulae[i]); + // If this is reuse-by-noop-cast, insert the noop cast. + const Type *OpTy = LF.OperandValToReplace->getType(); + if (FullV->getType() != OpTy) { + Instruction *Cast = + CastInst::Create(CastInst::getCastOpcode(FullV, false, OpTy, false), + FullV, OpTy, "tmp", LF.UserInst); + FullV = Cast; + } + + // Update the user. ICmpZero is handled specially here (for now) because + // Expand may have updated one of the operands of the icmp already, and + // its new value may happen to be equal to LF.OperandValToReplace, in + // which case doing replaceUsesOfWith leads to replacing both operands + // with the same value. TODO: Reorganize this. + if (Uses[LF.LUIdx].Kind == LSRUse::ICmpZero) + LF.UserInst->setOperand(0, FullV); + else + LF.UserInst->replaceUsesOfWith(LF.OperandValToReplace, FullV); } - GenerateConstantOffsetReuse(); + DeadInsts.push_back(LF.OperandValToReplace); } -/// GenerateLoopInvariantRegisterUses - Check for other uses of loop-invariant -/// values which we're tracking. These other uses will pin these values in -/// registers, making them less profitable for elimination. -/// TODO: This currently misses non-constant addrec step registers. -/// TODO: Should this give more weight to users inside the loop? void -LSRInstance::GenerateLoopInvariantRegisterUses() { - SmallVector Worklist(RegSequence.begin(), RegSequence.end()); +LSRInstance::ImplementSolution(const SmallVectorImpl &Solution, + Pass *P) { + // Keep track of instructions we may have made dead, so that + // we can remove them after we are done working. + SmallVector DeadInsts; - while (!Worklist.empty()) { - const SCEV *S = Worklist.pop_back_val(); + SCEVExpander Rewriter(SE); + Rewriter.disableCanonicalMode(); + Rewriter.setIVIncInsertPos(L, IVIncInsertPos); - if (const SCEVNAryExpr *N = dyn_cast(S)) - Worklist.insert(Worklist.end(), N->op_begin(), N->op_end()); - else if (const SCEVCastExpr *C = dyn_cast(S)) - Worklist.push_back(C->getOperand()); - else if (const SCEVUDivExpr *D = dyn_cast(S)) { - Worklist.push_back(D->getLHS()); - Worklist.push_back(D->getRHS()); - } else if (const SCEVUnknown *U = dyn_cast(S)) { - const Value *V = U->getValue(); - if (const Instruction *Inst = dyn_cast(V)) - if (L->contains(Inst)) continue; - for (Value::use_const_iterator UI = V->use_begin(), UE = V->use_end(); - UI != UE; ++UI) { - const Instruction *UserInst = dyn_cast(*UI); - // Ignore non-instructions. - if (!UserInst) - continue; - // Ignore instructions in other functions (as can happen with - // Constants). - if (UserInst->getParent()->getParent() != L->getHeader()->getParent()) - continue; - // Ignore instructions not dominated by the loop. - const BasicBlock *UseBB = !isa(UserInst) ? - UserInst->getParent() : - cast(UserInst)->getIncomingBlock( - PHINode::getIncomingValueNumForOperand(UI.getOperandNo())); - if (!DT.dominates(L->getHeader(), UseBB)) - continue; - // Ignore uses which are part of other SCEV expressions, to avoid - // analyzing them multiple times. - if (SE.isSCEVable(UserInst->getType()) && - !isa(SE.getSCEV(const_cast(UserInst)))) - continue; - // Ignore icmp instructions which are already being analyzed. - if (const ICmpInst *ICI = dyn_cast(UserInst)) { - unsigned OtherIdx = !UI.getOperandNo(); - Value *OtherOp = const_cast(ICI->getOperand(OtherIdx)); - if (SE.getSCEV(OtherOp)->hasComputableLoopEvolution(L)) - continue; - } + // Expand the new value definitions and update the users. + for (size_t i = 0, e = Fixups.size(); i != e; ++i) { + size_t LUIdx = Fixups[i].LUIdx; - LSRUse &LU = getNewUse(); - LU.UserInst = const_cast(UserInst); - LU.OperandValToReplace = UI.getUse(); - LU.InsertSupplementalFormula(U); - CountRegisters(LU.Formulae.back(), Uses.size() - 1); - } - } + Rewrite(Fixups[i], *Solution[LUIdx], Rewriter, DeadInsts, P); + + Changed = true; } -} -#ifndef NDEBUG + // Clean up after ourselves. This must be done before deleting any + // instructions. + Rewriter.clear(); -static void debug_winner(SmallVector const &Uses) { - dbgs() << "LSR has selected formulae for each use:\n"; - for (SmallVectorImpl::const_iterator I = Uses.begin(), - E = Uses.end(); I != E; ++I) { - const LSRUse &LU = *I; - dbgs() << " "; - LU.print(dbgs()); - dbgs() << '\n'; - dbgs() << " "; - LU.Formulae.front().print(dbgs()); - dbgs() << "\n"; - } + Changed |= DeleteTriviallyDeadInstructions(DeadInsts); } -#endif - LSRInstance::LSRInstance(const TargetLowering *tli, Loop *l, Pass *P) : IU(P->getAnalysis()), SE(P->getAnalysis()), DT(P->getAnalysis()), - TLI(tli), L(l), Changed(false), CurrentArbitraryRegIndex(0), MaxNumRegs(0) { + TLI(tli), L(l), Changed(false), IVIncInsertPos(0) { // If LoopSimplify form is not available, stay out of trouble. if (!L->isLoopSimplifyForm()) return; // If there's no interesting work to be done, bail early. - if (IU.IVUsesByStride.empty()) return; + if (IU.empty()) return; DEBUG(dbgs() << "\nLSR on loop "; WriteAsOperand(dbgs(), L->getHeader(), /*PrintType=*/false); dbgs() << ":\n"); - // Sort the StrideOrder so we process larger strides first. - std::stable_sort(IU.StrideOrder.begin(), IU.StrideOrder.end(), - StrideCompare(SE)); - /// OptimizeShadowIV - If IV is used in a int-to-float cast - /// inside the loop then try to eliminate the cast opeation. + /// inside the loop then try to eliminate the cast operation. OptimizeShadowIV(); // Change loop terminating condition to use the postinc iv when possible. - Instruction *IVIncInsertPos; - Changed |= OptimizeLoopTermCond(IVIncInsertPos); - - for (SmallVectorImpl::const_iterator SIter = - IU.StrideOrder.begin(), SEnd = IU.StrideOrder.end(); - SIter != SEnd; ++SIter) { - const SCEV *Stride = *SIter; - - // Collect interesting types. - Types.insert(SE.getEffectiveSCEVType(Stride->getType())); - - // Collect interesting factors. - for (SmallVectorImpl::const_iterator NewStrideIter = - SIter + 1; NewStrideIter != SEnd; ++NewStrideIter) { - const SCEV *OldStride = Stride; - const SCEV *NewStride = *NewStrideIter; - - if (SE.getTypeSizeInBits(OldStride->getType()) != - SE.getTypeSizeInBits(NewStride->getType())) { - if (SE.getTypeSizeInBits(OldStride->getType()) > - SE.getTypeSizeInBits(NewStride->getType())) - NewStride = SE.getSignExtendExpr(NewStride, OldStride->getType()); - else - OldStride = SE.getSignExtendExpr(OldStride, NewStride->getType()); - } - if (const SCEVConstant *Factor = - dyn_cast_or_null(getSDiv(NewStride, OldStride, - SE, true))) - if (Factor->getValue()->getValue().getMinSignedBits() <= 64) - Factors.insert(Factor->getValue()->getValue().getSExtValue()); - } - - std::map::const_iterator SI = - IU.IVUsesByStride.find(Stride); - assert(SI != IU.IVUsesByStride.end() && "Stride doesn't exist!"); - for (ilist::const_iterator UI = SI->second->Users.begin(), - E = SI->second->Users.end(); UI != E; ++UI) { - // Record the uses. - LSRUse &LU = getNewUse(); - LU.UserInst = UI->getUser(); - LU.OperandValToReplace = UI->getOperandValToReplace(); - if (isAddressUse(LU.UserInst, LU.OperandValToReplace)) { - LU.Kind = LSRUse::Address; - LU.AccessTy = getAccessType(LU.UserInst); - } - if (UI->isUseOfPostIncrementedValue()) - LU.PostIncLoop = L; - - const SCEV *S = IU.getCanonicalExpr(*UI); - - // Equality (== and !=) ICmps are special. We can rewrite (i == N) as - // (N - i == 0), and this allows (N - i) to be the expression that we - // work with rather than just N or i, so we can consider the register - // requirements for both N and i at the same time. Limiting this code - // to equality icmps is not a problem because all interesting loops - // use equality icmps, thanks to IndVarSimplify. - if (ICmpInst *CI = dyn_cast(LU.UserInst)) - if (CI->isEquality()) { - // Swap the operands if needed to put the OperandValToReplace on - // the left, for consistency. - Value *NV = CI->getOperand(1); - if (NV == LU.OperandValToReplace) { - CI->setOperand(1, CI->getOperand(0)); - CI->setOperand(0, NV); - } - - // x == y --> x - y == 0 - const SCEV *N = SE.getSCEV(NV); - if (N->isLoopInvariant(L)) { - LU.Kind = LSRUse::ICmpZero; - S = SE.getMinusSCEV(N, S); - } - - // -1 and the negations of all interesting strides (except the - // negation of -1) are now also interesting. - for (size_t i = 0, e = Factors.size(); i != e; ++i) - if (Factors[i] != -1) - Factors.insert(-(uint64_t)Factors[i]); - Factors.insert(-1); - } - - // Ok, now enumerate all the different formulae we can find to compute - // the value for this expression. - LU.InsertInitialFormula(S, L, SE, DT); - CountRegisters(LU.Formulae.back(), Uses.size() - 1); - } - } - - // If all uses use the same type, don't bother looking for truncation-based - // reuse. - if (Types.size() == 1) - Types.clear(); + Changed |= OptimizeLoopTermCond(); - // If there are any uses of registers that we're tracking that have escaped - // IVUsers' attention, add trivial uses for them, so that the register - // voting process takes the into consideration. - GenerateLoopInvariantRegisterUses(); + CollectInterestingTypesAndFactors(); + CollectFixupsAndInitialFormulae(); + CollectLoopInvariantFixupsAndFormulae(); - // Start by assuming we'll assign each use its own register. This is - // sometimes called "full" strength reduction, or "superhero" mode. - // Sometimes this is the best solution, but if there are opportunities for - // reuse we may find a better solution. - Score CurScore; - CurScore.RateInitial(Uses, L, SE); - - MaxNumRegs = CurScore.getNumRegs(); + DEBUG(dbgs() << "LSR found " << Uses.size() << " uses:\n"; + print_uses(dbgs())); // Now use the reuse data to generate a bunch of interesting ways // to formulate the values needed for the uses. GenerateAllReuseFormulae(); - // Sort the formulae. TODO: This is redundantly sorted below. - for (SmallVectorImpl::iterator I = Uses.begin(), E = Uses.end(); - I != E; ++I) { - LSRUse &LU = *I; - std::stable_sort(LU.Formulae.begin(), LU.Formulae.end(), - ComplexitySorter()); - } - - // Ok, we've now collected all the uses and noted their register uses. The - // next step is to start looking at register reuse possibilities. - DEBUG(print(dbgs()); dbgs() << '\n'; IU.dump()); - - // Create a sorted list of registers with those with the most uses appearing - // earlier in the list. We'll visit them first, as they're the most likely - // to represent profitable reuse opportunities. - SmallVector RegOrder; - for (SmallVectorImpl::const_iterator I = - RegSequence.begin(), E = RegSequence.end(); I != E; ++I) - RegOrder.push_back(RegCount(*I, RegUses.find(*I)->second)); - std::stable_sort(RegOrder.begin(), RegOrder.end()); - - // Visit each register. Determine which ones represent profitable reuse - // opportunities and remember them. - // TODO: Extract this code into a function. - for (SmallVectorImpl::const_iterator I = RegOrder.begin(), - E = RegOrder.end(); I != E; ++I) { - const SCEV *Reg = I->Reg; - const SmallBitVector &Bits = I->Sort.Bits; - - // Registers with only one use don't represent reuse opportunities, so - // when we get there, we're done. - if (Bits.count() <= 1) break; - - DEBUG(dbgs() << "Reg " << *Reg << ": "; - I->Sort.print(dbgs()); - dbgs() << '\n'); - - // Determine the total number of registers will be needed if we make use - // of the reuse opportunity represented by the current register. - Score NewScore; - NewScore.Rate(Reg, Bits, Uses, L, SE); - - // Now decide whether this register's reuse opportunity is an overall win. - // Currently the decision is heavily skewed for register pressure. - if (!(NewScore < CurScore)) { - continue; - } + DEBUG(dbgs() << "\n" + "After generating reuse formulae:\n"; + print_uses(dbgs())); - // Ok, use this opportunity. - DEBUG(dbgs() << "This candidate has been accepted.\n"); - CurScore = NewScore; - - // Now that we've selected a new reuse opportunity, delete formulae that - // do not participate in that opportunity. - for (int j = Bits.find_first(); j != -1; j = Bits.find_next(j)) { - LSRUse &LU = Uses[j]; - for (unsigned k = 0, h = LU.Formulae.size(); k != h; ++k) { - Formula &F = LU.Formulae[k]; - if (!F.referencesReg(Reg)) { - std::swap(LU.Formulae[k], LU.Formulae.back()); - LU.Formulae.pop_back(); - --k; --h; - } - } - // Also re-sort the list to put the formulae with the fewest registers - // at the front. - // TODO: Do this earlier, we don't need it each time. - std::stable_sort(LU.Formulae.begin(), LU.Formulae.end(), - ComplexitySorter()); - } - } + FilterOutUndesirableDedicatedRegisters(); + NarrowSearchSpaceUsingHeuristics(); - // Ok, we've now made all our decisions. The first formula for each use - // will be used. - DEBUG(dbgs() << "Concluding, we need "; CurScore.print(dbgs()); - dbgs() << ".\n"; - debug_winner(Uses)); + SmallVector Solution; + Solve(Solution); + assert(Solution.size() == Uses.size() && "Malformed solution!"); - // Free memory no longer needed. - RegOrder.clear(); + // Release memory that is no longer needed. Factors.clear(); Types.clear(); RegUses.clear(); - RegSequence.clear(); - - // Keep track of instructions we may have made dead, so that - // we can remove them after we are done working. - SmallVector DeadInsts; - - SCEVExpander Rewriter(SE); - Rewriter.disableCanonicalMode(); - Rewriter.setIVIncInsertPos(L, IVIncInsertPos); - // Expand the new value definitions and update the users. +#ifndef NDEBUG + // Formulae should be legal. for (SmallVectorImpl::const_iterator I = Uses.begin(), E = Uses.end(); I != E; ++I) { - // Formulae should be legal. - DEBUG(for (SmallVectorImpl::const_iterator J = I->Formulae.begin(), - JE = I->Formulae.end(); J != JE; ++J) - assert(isLegalUse(J->AM, I->Kind, I->AccessTy, TLI) && - "Illegal formula generated!")); - - // Expand the new code and update the user. - I->Rewrite(L, Rewriter, DeadInsts, SE, DT, P); - Changed = true; - } - - // Clean up after ourselves. This must be done before deleting any - // instructions. - Rewriter.clear(); + const LSRUse &LU = *I; + for (SmallVectorImpl::const_iterator J = LU.Formulae.begin(), + JE = LU.Formulae.end(); J != JE; ++J) + assert(isLegalUse(J->AM, LU.MinOffset, LU.MaxOffset, + LU.Kind, LU.AccessTy, TLI) && + "Illegal formula generated!"); + }; +#endif - Changed |= DeleteTriviallyDeadInstructions(DeadInsts); + // Now that we've decided what we want, make it so. + ImplementSolution(Solution, P); } -void LSRInstance::print(raw_ostream &OS) const { - if (MaxNumRegs != 0) - OS << "LSR is considering " << MaxNumRegs << " to be the maximum " - "number of registers needed.\n"; +void LSRInstance::print_factors_and_types(raw_ostream &OS) const { + if (Factors.empty() && Types.empty()) return; OS << "LSR has identified the following interesting factors and types: "; bool First = true; - for (SmallSetVector::const_iterator + for (SmallSetVector::const_iterator I = Factors.begin(), E = Factors.end(); I != E; ++I) { if (!First) OS << ", "; First = false; @@ -2721,8 +3178,21 @@ void LSRInstance::print(raw_ostream &OS) const { OS << '(' << **I << ')'; } OS << '\n'; +} - OS << "LSR is examining the following uses, and candidate formulae:\n"; +void LSRInstance::print_fixups(raw_ostream &OS) const { + OS << "LSR is examining the following fixup sites:\n"; + for (SmallVectorImpl::const_iterator I = Fixups.begin(), + E = Fixups.end(); I != E; ++I) { + const LSRFixup &LF = *I; + dbgs() << " "; + LF.print(OS); + OS << '\n'; + } +} + +void LSRInstance::print_uses(raw_ostream &OS) const { + OS << "LSR is examining the following uses:\n"; for (SmallVectorImpl::const_iterator I = Uses.begin(), E = Uses.end(); I != E; ++I) { const LSRUse &LU = *I; @@ -2733,11 +3203,17 @@ void LSRInstance::print(raw_ostream &OS) const { JE = LU.Formulae.end(); J != JE; ++J) { OS << " "; J->print(OS); - OS << "\n"; + OS << '\n'; } } } +void LSRInstance::print(raw_ostream &OS) const { + print_factors_and_types(OS); + print_fixups(OS); + print_uses(OS); +} + void LSRInstance::dump() const { print(errs()); errs() << '\n'; } @@ -2751,7 +3227,7 @@ class LoopStrengthReduce : public LoopPass { public: static char ID; // Pass ID, replacement for typeid - explicit LoopStrengthReduce(const TargetLowering *tli = NULL); + explicit LoopStrengthReduce(const TargetLowering *tli = 0); private: bool runOnLoop(Loop *L, LPPassManager &LPM);