X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FAnalysis%2FScalarEvolution.h;h=e1d1aa3bfac2c9d6d08f25b28b85d2a2daf8a83e;hb=529919ff310cbfce1ba55ea252ff738d5b56b93d;hp=49e8fa3663452822f97a5342ac26d3ff4b7ee4df;hpb=db125cfaf57cc83e7dd7453de2d509bc8efd0e5e;p=oota-llvm.git diff --git a/include/llvm/Analysis/ScalarEvolution.h b/include/llvm/Analysis/ScalarEvolution.h index 49e8fa36634..e1d1aa3bfac 100644 --- a/include/llvm/Analysis/ScalarEvolution.h +++ b/include/llvm/Analysis/ScalarEvolution.h @@ -21,26 +21,28 @@ #ifndef LLVM_ANALYSIS_SCALAREVOLUTION_H #define LLVM_ANALYSIS_SCALAREVOLUTION_H +#include "llvm/ADT/DenseSet.h" +#include "llvm/ADT/FoldingSet.h" +#include "llvm/IR/ConstantRange.h" +#include "llvm/IR/Function.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/Operator.h" +#include "llvm/IR/ValueHandle.h" #include "llvm/Pass.h" -#include "llvm/Instructions.h" -#include "llvm/Function.h" -#include "llvm/Operator.h" -#include "llvm/Support/DataTypes.h" -#include "llvm/Support/ValueHandle.h" #include "llvm/Support/Allocator.h" -#include "llvm/Support/ConstantRange.h" -#include "llvm/ADT/FoldingSet.h" -#include "llvm/ADT/DenseMap.h" +#include "llvm/Support/DataTypes.h" #include namespace llvm { class APInt; + class AssumptionCache; class Constant; class ConstantInt; class DominatorTree; class Type; class ScalarEvolution; - class TargetData; + class DataLayout; + class TargetLibraryInfo; class LLVMContext; class Loop; class LoopInfo; @@ -69,8 +71,8 @@ namespace llvm { unsigned short SubclassData; private: - SCEV(const SCEV &); // DO NOT IMPLEMENT - void operator=(const SCEV &); // DO NOT IMPLEMENT + SCEV(const SCEV &) = delete; + void operator=(const SCEV &) = delete; public: /// NoWrapFlags are bitfield indices into SubclassData. @@ -80,12 +82,13 @@ namespace llvm { /// operator. NSW is a misnomer that we use to mean no signed overflow or /// underflow. /// - /// AddRec expression may have a no-self-wraparound property if the - /// result can never reach the start value. This property is independent of - /// the actual start value and step direction. Self-wraparound is defined - /// purely in terms of the recurrence's loop, step size, and - /// bitwidth. Formally, a recurrence with no self-wraparound satisfies: - /// abs(step) * max-iteration(loop) <= unsigned-max(bitwidth). + /// AddRec expressions may have a no-self-wraparound property if, in + /// the integer domain, abs(step) * max-iteration(loop) <= + /// unsigned-max(bitwidth). This means that the recurrence will never reach + /// its start value if the step is non-zero. Computing the same value on + /// each iteration is not considered wrapping, and recurrences with step = 0 + /// are trivially . is independent of the sign of step and the + /// value the add recurrence starts with. /// /// Note that NUW and NSW are also valid properties of a recurrence, and /// either implies NW. For convenience, NW will be set for a recurrence @@ -118,14 +121,20 @@ namespace llvm { /// bool isAllOnesValue() const; + /// isNonConstantNegative - Return true if the specified scev is negated, + /// but not a constant. + bool isNonConstantNegative() const; + /// print - Print out the internal representation of this scalar to the /// specified stream. This should really only be used for debugging /// purposes. void print(raw_ostream &OS) const; +#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) /// dump - This method is used for debugging. /// void dump() const; +#endif }; // Specialize FoldingSetTrait for SCEV to avoid needing to compute @@ -135,7 +144,7 @@ namespace llvm { ID = X.FastID; } static bool Equals(const SCEV &X, const FoldingSetNodeID &ID, - FoldingSetNodeID &TempID) { + unsigned IDHash, FoldingSetNodeID &TempID) { return ID == X.FastID; } static unsigned ComputeHash(const SCEV &X, FoldingSetNodeID &TempID) { @@ -157,7 +166,6 @@ namespace llvm { SCEVCouldNotCompute(); /// Methods for support type inquiry through isa, cast, and dyn_cast: - static inline bool classof(const SCEVCouldNotCompute *S) { return true; } static bool classof(const SCEV *S); }; @@ -185,15 +193,16 @@ namespace llvm { /// Convenient NoWrapFlags manipulation that hides enum casts and is /// visible in the ScalarEvolution name space. - static SCEV::NoWrapFlags maskFlags(SCEV::NoWrapFlags Flags, int Mask) { + static SCEV::NoWrapFlags LLVM_ATTRIBUTE_UNUSED_RESULT + maskFlags(SCEV::NoWrapFlags Flags, int Mask) { return (SCEV::NoWrapFlags)(Flags & Mask); } - static SCEV::NoWrapFlags setFlags(SCEV::NoWrapFlags Flags, - SCEV::NoWrapFlags OnFlags) { + static SCEV::NoWrapFlags LLVM_ATTRIBUTE_UNUSED_RESULT + setFlags(SCEV::NoWrapFlags Flags, SCEV::NoWrapFlags OnFlags) { return (SCEV::NoWrapFlags)(Flags | OnFlags); } - static SCEV::NoWrapFlags clearFlags(SCEV::NoWrapFlags Flags, - SCEV::NoWrapFlags OffFlags) { + static SCEV::NoWrapFlags LLVM_ATTRIBUTE_UNUSED_RESULT + clearFlags(SCEV::NoWrapFlags Flags, SCEV::NoWrapFlags OffFlags) { return (SCEV::NoWrapFlags)(Flags & ~OffFlags); } @@ -202,10 +211,10 @@ namespace llvm { /// notified whenever a Value is deleted. class SCEVCallbackVH : public CallbackVH { ScalarEvolution *SE; - virtual void deleted(); - virtual void allUsesReplacedWith(Value *New); + void deleted() override; + void allUsesReplacedWith(Value *New) override; public: - SCEVCallbackVH(Value *V, ScalarEvolution *SE = 0); + SCEVCallbackVH(Value *V, ScalarEvolution *SE = nullptr); }; friend class SCEVCallbackVH; @@ -216,13 +225,16 @@ namespace llvm { /// Function *F; + /// The tracker for @llvm.assume intrinsics in this function. + AssumptionCache *AC; + /// LI - The loop information for the function we are currently analyzing. /// LoopInfo *LI; - /// TD - The target data information for the target we are targeting. + /// TLI - The target library information for the target we are targeting. /// - TargetData *TD; + TargetLibraryInfo *TLI; /// DT - The dominator tree. /// @@ -241,31 +253,101 @@ namespace llvm { /// ValueExprMapType ValueExprMap; + /// Mark predicate values currently being processed by isImpliedCond. + DenseSet PendingLoopPredicates; + + /// ExitLimit - Information about the number of loop iterations for which a + /// loop exit's branch condition evaluates to the not-taken path. This is a + /// temporary pair of exact and max expressions that are eventually + /// summarized in ExitNotTakenInfo and BackedgeTakenInfo. + struct ExitLimit { + const SCEV *Exact; + const SCEV *Max; + + /*implicit*/ ExitLimit(const SCEV *E) : Exact(E), Max(E) {} + + ExitLimit(const SCEV *E, const SCEV *M) : Exact(E), Max(M) {} + + /// hasAnyInfo - Test whether this ExitLimit contains any computed + /// information, or whether it's all SCEVCouldNotCompute values. + bool hasAnyInfo() const { + return !isa(Exact) || + !isa(Max); + } + }; + + /// ExitNotTakenInfo - Information about the number of times a particular + /// loop exit may be reached before exiting the loop. + struct ExitNotTakenInfo { + AssertingVH ExitingBlock; + const SCEV *ExactNotTaken; + PointerIntPair NextExit; + + ExitNotTakenInfo() : ExitingBlock(nullptr), ExactNotTaken(nullptr) {} + + /// isCompleteList - Return true if all loop exits are computable. + bool isCompleteList() const { + return NextExit.getInt() == 0; + } + + void setIncomplete() { NextExit.setInt(1); } + + /// getNextExit - Return a pointer to the next exit's not-taken info. + ExitNotTakenInfo *getNextExit() const { + return NextExit.getPointer(); + } + + void setNextExit(ExitNotTakenInfo *ENT) { NextExit.setPointer(ENT); } + }; + /// BackedgeTakenInfo - Information about the backedge-taken count /// of a loop. This currently includes an exact count and a maximum count. /// - struct BackedgeTakenInfo { - /// Exact - An expression indicating the exact backedge-taken count of - /// the loop if it is known, or a SCEVCouldNotCompute otherwise. - const SCEV *Exact; + class BackedgeTakenInfo { + /// ExitNotTaken - A list of computable exits and their not-taken counts. + /// Loops almost never have more than one computable exit. + ExitNotTakenInfo ExitNotTaken; /// Max - An expression indicating the least maximum backedge-taken /// count of the loop that is known, or a SCEVCouldNotCompute. const SCEV *Max; - /*implicit*/ BackedgeTakenInfo(const SCEV *exact) : - Exact(exact), Max(exact) {} + public: + BackedgeTakenInfo() : Max(nullptr) {} - BackedgeTakenInfo(const SCEV *exact, const SCEV *max) : - Exact(exact), Max(max) {} + /// Initialize BackedgeTakenInfo from a list of exact exit counts. + BackedgeTakenInfo( + SmallVectorImpl< std::pair > &ExitCounts, + bool Complete, const SCEV *MaxCount); /// hasAnyInfo - Test whether this BackedgeTakenInfo contains any /// computed information, or whether it's all SCEVCouldNotCompute /// values. bool hasAnyInfo() const { - return !isa(Exact) || - !isa(Max); + return ExitNotTaken.ExitingBlock || !isa(Max); } + + /// getExact - Return an expression indicating the exact backedge-taken + /// count of the loop if it is known, or SCEVCouldNotCompute + /// otherwise. This is the number of times the loop header can be + /// guaranteed to execute, minus one. + const SCEV *getExact(ScalarEvolution *SE) const; + + /// getExact - Return the number of times this loop exit may fall through + /// to the back edge, or SCEVCouldNotCompute. The loop is guaranteed not + /// to exit via this block before this number of iterations, but may exit + /// via another block. + const SCEV *getExact(BasicBlock *ExitingBlock, ScalarEvolution *SE) const; + + /// getMax - Get the max backedge taken count for the loop. + const SCEV *getMax(ScalarEvolution *SE) const; + + /// Return true if any backedge taken count expressions refer to the given + /// subexpression. + bool hasOperand(const SCEV *S, ScalarEvolution *SE) const; + + /// clear - Invalidate this result and free associated memory. + void clear(); }; /// BackedgeTakenCounts - Cache the backedge-taken count of the loops for @@ -283,48 +365,50 @@ namespace llvm { /// that we attempt to compute getSCEVAtScope information for, which can /// be expensive in extreme cases. DenseMap > ValuesAtScopes; + SmallVector, 2> > ValuesAtScopes; /// LoopDispositions - Memoized computeLoopDisposition results. DenseMap > LoopDispositions; + SmallVector, 2>> + LoopDispositions; /// computeLoopDisposition - Compute a LoopDisposition value. LoopDisposition computeLoopDisposition(const SCEV *S, const Loop *L); /// BlockDispositions - Memoized computeBlockDisposition results. - DenseMap > BlockDispositions; + DenseMap< + const SCEV *, + SmallVector, 2>> + BlockDispositions; /// computeBlockDisposition - Compute a BlockDisposition value. BlockDisposition computeBlockDisposition(const SCEV *S, const BasicBlock *BB); - /// UnsignedRanges - Memoized results from getUnsignedRange + /// UnsignedRanges - Memoized results from getRange DenseMap UnsignedRanges; - /// SignedRanges - Memoized results from getSignedRange + /// SignedRanges - Memoized results from getRange DenseMap SignedRanges; - /// setUnsignedRange - Set the memoized unsigned range for the given SCEV. - const ConstantRange &setUnsignedRange(const SCEV *S, - const ConstantRange &CR) { - std::pair::iterator, bool> Pair = - UnsignedRanges.insert(std::make_pair(S, CR)); - if (!Pair.second) - Pair.first->second = CR; - return Pair.first->second; - } + /// RangeSignHint - Used to parameterize getRange + enum RangeSignHint { HINT_RANGE_UNSIGNED, HINT_RANGE_SIGNED }; + + /// setRange - Set the memoized range for the given SCEV. + const ConstantRange &setRange(const SCEV *S, RangeSignHint Hint, + const ConstantRange &CR) { + DenseMap &Cache = + Hint == HINT_RANGE_UNSIGNED ? UnsignedRanges : SignedRanges; - /// setUnsignedRange - Set the memoized signed range for the given SCEV. - const ConstantRange &setSignedRange(const SCEV *S, - const ConstantRange &CR) { std::pair::iterator, bool> Pair = - SignedRanges.insert(std::make_pair(S, CR)); + Cache.insert(std::make_pair(S, CR)); if (!Pair.second) Pair.first->second = CR; return Pair.first->second; } + /// getRange - Determine the range for a particular SCEV. + ConstantRange getRange(const SCEV *S, RangeSignHint Hint); + /// createSCEV - We know that there is no SCEV for the specified value. /// Analyze the expression. const SCEV *createSCEV(Value *V); @@ -348,14 +432,6 @@ namespace llvm { /// resolution. void ForgetSymbolicName(Instruction *I, const SCEV *SymName); - /// getBECount - Subtract the end and start values and divide by the step, - /// rounding up, to get the number of times the backedge is executed. Return - /// CouldNotCompute if an intermediate computation overflows. - const SCEV *getBECount(const SCEV *Start, - const SCEV *End, - const SCEV *Step, - bool NoWrap); - /// getBackedgeTakenInfo - Return the BackedgeTakenInfo for the given /// loop, lazily computing new values if the loop hasn't been analyzed /// yet. @@ -365,64 +441,70 @@ namespace llvm { /// loop will iterate. BackedgeTakenInfo ComputeBackedgeTakenCount(const Loop *L); - /// ComputeBackedgeTakenCountFromExit - Compute the number of times the - /// backedge of the specified loop will execute if it exits via the - /// specified block. - BackedgeTakenInfo ComputeBackedgeTakenCountFromExit(const Loop *L, - BasicBlock *ExitingBlock); - - /// ComputeBackedgeTakenCountFromExitCond - Compute the number of times the - /// backedge of the specified loop will execute if its exit condition - /// were a conditional branch of ExitCond, TBB, and FBB. - BackedgeTakenInfo - ComputeBackedgeTakenCountFromExitCond(const Loop *L, - Value *ExitCond, - BasicBlock *TBB, - BasicBlock *FBB); - - /// ComputeBackedgeTakenCountFromExitCondICmp - Compute the number of - /// times the backedge of the specified loop will execute if its exit - /// condition were a conditional branch of the ICmpInst ExitCond, TBB, - /// and FBB. - BackedgeTakenInfo - ComputeBackedgeTakenCountFromExitCondICmp(const Loop *L, - ICmpInst *ExitCond, - BasicBlock *TBB, - BasicBlock *FBB); - - /// ComputeLoadConstantCompareBackedgeTakenCount - Given an exit condition + /// ComputeExitLimit - Compute the number of times the backedge of the + /// specified loop will execute if it exits via the specified block. + ExitLimit ComputeExitLimit(const Loop *L, BasicBlock *ExitingBlock); + + /// ComputeExitLimitFromCond - Compute the number of times the backedge of + /// the specified loop will execute if its exit condition were a conditional + /// branch of ExitCond, TBB, and FBB. + ExitLimit ComputeExitLimitFromCond(const Loop *L, + Value *ExitCond, + BasicBlock *TBB, + BasicBlock *FBB, + bool IsSubExpr); + + /// ComputeExitLimitFromICmp - Compute the number of times the backedge of + /// the specified loop will execute if its exit condition were a conditional + /// branch of the ICmpInst ExitCond, TBB, and FBB. + ExitLimit ComputeExitLimitFromICmp(const Loop *L, + ICmpInst *ExitCond, + BasicBlock *TBB, + BasicBlock *FBB, + bool IsSubExpr); + + /// ComputeExitLimitFromSingleExitSwitch - Compute the number of times the + /// backedge of the specified loop will execute if its exit condition were a + /// switch with a single exiting case to ExitingBB. + ExitLimit + ComputeExitLimitFromSingleExitSwitch(const Loop *L, SwitchInst *Switch, + BasicBlock *ExitingBB, bool IsSubExpr); + + /// ComputeLoadConstantCompareExitLimit - Given an exit condition /// of 'icmp op load X, cst', try to see if we can compute the /// backedge-taken count. - BackedgeTakenInfo - ComputeLoadConstantCompareBackedgeTakenCount(LoadInst *LI, - Constant *RHS, - const Loop *L, - ICmpInst::Predicate p); - - /// ComputeBackedgeTakenCountExhaustively - If the loop is known to execute - /// a constant number of times (the condition evolves only from constants), + ExitLimit ComputeLoadConstantCompareExitLimit(LoadInst *LI, + Constant *RHS, + const Loop *L, + ICmpInst::Predicate p); + + /// ComputeExitCountExhaustively - If the loop is known to execute a + /// constant number of times (the condition evolves only from constants), /// try to evaluate a few iterations of the loop until we get the exit /// condition gets a value of ExitWhen (true or false). If we cannot - /// evaluate the backedge-taken count of the loop, return CouldNotCompute. - const SCEV *ComputeBackedgeTakenCountExhaustively(const Loop *L, - Value *Cond, - bool ExitWhen); + /// evaluate the exit count of the loop, return CouldNotCompute. + const SCEV *ComputeExitCountExhaustively(const Loop *L, + Value *Cond, + bool ExitWhen); - /// HowFarToZero - Return the number of times a backedge comparing the - /// specified value to zero will execute. If not computable, return + /// HowFarToZero - Return the number of times an exit condition comparing + /// the specified value to zero will execute. If not computable, return /// CouldNotCompute. - BackedgeTakenInfo HowFarToZero(const SCEV *V, const Loop *L); + ExitLimit HowFarToZero(const SCEV *V, const Loop *L, bool IsSubExpr); - /// HowFarToNonZero - Return the number of times a backedge checking the - /// specified value for nonzero will execute. If not computable, return + /// HowFarToNonZero - Return the number of times an exit condition checking + /// the specified value for nonzero will execute. If not computable, return /// CouldNotCompute. - BackedgeTakenInfo HowFarToNonZero(const SCEV *V, const Loop *L); + ExitLimit HowFarToNonZero(const SCEV *V, const Loop *L); - /// HowManyLessThans - Return the number of times a backedge containing the - /// specified less-than comparison will execute. If not computable, return - /// CouldNotCompute. isSigned specifies whether the less-than is signed. - BackedgeTakenInfo HowManyLessThans(const SCEV *LHS, const SCEV *RHS, - const Loop *L, bool isSigned); + /// HowManyLessThans - Return the number of times an exit condition + /// containing the specified less-than comparison will execute. If not + /// computable, return CouldNotCompute. isSigned specifies whether the + /// less-than is signed. + ExitLimit HowManyLessThans(const SCEV *LHS, const SCEV *RHS, + const Loop *L, bool isSigned, bool IsSubExpr); + ExitLimit HowManyGreaterThans(const SCEV *LHS, const SCEV *RHS, + const Loop *L, bool isSigned, bool IsSubExpr); /// getPredecessorWithUniqueSuccessorForBB - Return a predecessor of BB /// (which may not be an immediate predecessor) which has exactly one @@ -450,7 +532,8 @@ namespace llvm { /// FoundLHS, and FoundRHS is true. bool isImpliedCondOperandsHelper(ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS, - const SCEV *FoundLHS, const SCEV *FoundRHS); + const SCEV *FoundLHS, + const SCEV *FoundRHS); /// getConstantEvolutionLoopExitValue - If we know that the specified Phi is /// in the header of its containing loop, we know the loop executes a @@ -469,6 +552,19 @@ namespace llvm { /// forgetMemoizedResults - Drop memoized information computed for S. void forgetMemoizedResults(const SCEV *S); + /// Return false iff given SCEV contains a SCEVUnknown with NULL value- + /// pointer. + bool checkValidity(const SCEV *S) const; + + // Return true if `ExtendOpTy`({`Start`,+,`Step`}) can be proved to be equal + // to {`ExtendOpTy`(`Start`),+,`ExtendOpTy`(`Step`)}. This is equivalent to + // proving no signed (resp. unsigned) wrap in {`Start`,+,`Step`} if + // `ExtendOpTy` is `SCEVSignExtendExpr` (resp. `SCEVZeroExtendExpr`). + // + template + bool proveNoWrapByVaryingStart(const SCEV *Start, const SCEV *Step, + const Loop *L); + public: static char ID; // Pass identification, replacement for typeid ScalarEvolution(); @@ -529,7 +625,16 @@ namespace llvm { Ops.push_back(RHS); return getMulExpr(Ops, Flags); } + const SCEV *getMulExpr(const SCEV *Op0, const SCEV *Op1, const SCEV *Op2, + SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap) { + SmallVector Ops; + Ops.push_back(Op0); + Ops.push_back(Op1); + Ops.push_back(Op2); + return getMulExpr(Ops, Flags); + } const SCEV *getUDivExpr(const SCEV *LHS, const SCEV *RHS); + const SCEV *getUDivExactExpr(const SCEV *LHS, const SCEV *RHS); const SCEV *getAddRecExpr(const SCEV *Start, const SCEV *Step, const Loop *L, SCEV::NoWrapFlags Flags); const SCEV *getAddRecExpr(SmallVectorImpl &Operands, @@ -548,21 +653,15 @@ namespace llvm { const SCEV *getUnknown(Value *V); const SCEV *getCouldNotCompute(); - /// getSizeOfExpr - Return an expression for sizeof on the given type. - /// - const SCEV *getSizeOfExpr(Type *AllocTy); - - /// getAlignOfExpr - Return an expression for alignof on the given type. - /// - const SCEV *getAlignOfExpr(Type *AllocTy); - - /// getOffsetOfExpr - Return an expression for offsetof on the given field. + /// getSizeOfExpr - Return an expression for sizeof AllocTy that is type + /// IntTy /// - const SCEV *getOffsetOfExpr(StructType *STy, unsigned FieldNo); + const SCEV *getSizeOfExpr(Type *IntTy, Type *AllocTy); - /// getOffsetOfExpr - Return an expression for offsetof on the given field. + /// getOffsetOfExpr - Return an expression for offsetof on the given field + /// with type IntTy /// - const SCEV *getOffsetOfExpr(Type *CTy, Constant *FieldNo); + const SCEV *getOffsetOfExpr(Type *IntTy, StructType *STy, unsigned FieldNo); /// getNegativeSCEV - Return the SCEV object corresponding to -V. /// @@ -653,6 +752,43 @@ namespace llvm { bool isLoopBackedgeGuardedByCond(const Loop *L, ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS); + /// \brief Returns the maximum trip count of the loop if it is a single-exit + /// loop and we can compute a small maximum for that loop. + /// + /// Implemented in terms of the \c getSmallConstantTripCount overload with + /// the single exiting block passed to it. See that routine for details. + unsigned getSmallConstantTripCount(Loop *L); + + /// getSmallConstantTripCount - Returns the maximum trip count of this loop + /// as a normal unsigned value. Returns 0 if the trip count is unknown or + /// not constant. This "trip count" assumes that control exits via + /// ExitingBlock. More precisely, it is the number of times that control may + /// reach ExitingBlock before taking the branch. For loops with multiple + /// exits, it may not be the number times that the loop header executes if + /// the loop exits prematurely via another branch. + unsigned getSmallConstantTripCount(Loop *L, BasicBlock *ExitingBlock); + + /// \brief Returns the largest constant divisor of the trip count of the + /// loop if it is a single-exit loop and we can compute a small maximum for + /// that loop. + /// + /// Implemented in terms of the \c getSmallConstantTripMultiple overload with + /// the single exiting block passed to it. See that routine for details. + unsigned getSmallConstantTripMultiple(Loop *L); + + /// getSmallConstantTripMultiple - Returns the largest constant divisor of + /// the trip count of this loop as a normal unsigned value, if + /// possible. This means that the actual trip count is always a multiple of + /// the returned value (don't forget the trip count could very well be zero + /// as well!). As explained in the comments for getSmallConstantTripCount, + /// this assumes that control exits the loop via ExitingBlock. + unsigned getSmallConstantTripMultiple(Loop *L, BasicBlock *ExitingBlock); + + // getExitCount - Get the expression for the number of loop iterations for + // which this loop is guaranteed not to exit via ExitingBlock. Otherwise + // return SCEVCouldNotCompute. + const SCEV *getExitCount(Loop *L, BasicBlock *ExitingBlock); + /// getBackedgeTakenCount - If the specified loop has a predictable /// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute /// object. The backedge-taken count is the number of times the loop header @@ -677,7 +813,8 @@ namespace llvm { /// forgetLoop - This method should be called by the client when it has /// changed a loop in a way that may effect ScalarEvolution's ability to - /// compute a trip count, or if the loop is deleted. + /// compute a trip count, or if the loop is deleted. This call is + /// potentially expensive for large loop bodies. void forgetLoop(const Loop *L); /// forgetValue - This method should be called by the client when it has @@ -685,6 +822,13 @@ namespace llvm { /// disconnect it from a def-use chain linking it to a loop. void forgetValue(Value *V); + /// \brief Called when the client has changed the disposition of values in + /// this loop. + /// + /// We don't have a way to invalidate per-loop dispositions. Clear and + /// recompute is simpler. + void forgetLoopDispositions(const Loop *L) { LoopDispositions.clear(); } + /// GetMinTrailingZeros - Determine the minimum number of zero bits that S /// is guaranteed to end in (at every loop iteration). It is, at the same /// time, the minimum number of times S is divisible by 2. For example, @@ -694,11 +838,15 @@ namespace llvm { /// getUnsignedRange - Determine the unsigned range for a particular SCEV. /// - ConstantRange getUnsignedRange(const SCEV *S); + ConstantRange getUnsignedRange(const SCEV *S) { + return getRange(S, HINT_RANGE_UNSIGNED); + } /// getSignedRange - Determine the signed range for a particular SCEV. /// - ConstantRange getSignedRange(const SCEV *S); + ConstantRange getSignedRange(const SCEV *S) { + return getRange(S, HINT_RANGE_SIGNED); + } /// isKnownNegative - Test if the given expression is known to be negative. /// @@ -731,12 +879,13 @@ namespace llvm { /// SimplifyICmpOperands - Simplify LHS and RHS in a comparison with /// predicate Pred. Return true iff any changes were made. If the - /// operands are provably equal or inequal, LHS and RHS are set to + /// operands are provably equal or unequal, LHS and RHS are set to /// the same value and Pred is set to either ICMP_EQ or ICMP_NE. /// bool SimplifyICmpOperands(ICmpInst::Predicate &Pred, const SCEV *&LHS, - const SCEV *&RHS); + const SCEV *&RHS, + unsigned Depth = 0); /// getLoopDisposition - Return the "disposition" of the given SCEV with /// respect to the given loop. @@ -768,10 +917,38 @@ namespace llvm { /// indirect operand. bool hasOperand(const SCEV *S, const SCEV *Op) const; - virtual bool runOnFunction(Function &F); - virtual void releaseMemory(); - virtual void getAnalysisUsage(AnalysisUsage &AU) const; - virtual void print(raw_ostream &OS, const Module* = 0) const; + /// Return the size of an element read or written by Inst. + const SCEV *getElementSize(Instruction *Inst); + + /// Compute the array dimensions Sizes from the set of Terms extracted from + /// the memory access function of this SCEVAddRecExpr. + void findArrayDimensions(SmallVectorImpl &Terms, + SmallVectorImpl &Sizes, + const SCEV *ElementSize) const; + + bool runOnFunction(Function &F) override; + void releaseMemory() override; + void getAnalysisUsage(AnalysisUsage &AU) const override; + void print(raw_ostream &OS, const Module* = nullptr) const override; + void verifyAnalysis() const override; + + private: + /// Compute the backedge taken count knowing the interval difference, the + /// stride and presence of the equality in the comparison. + const SCEV *computeBECount(const SCEV *Delta, const SCEV *Stride, + bool Equality); + + /// Verify if an linear IV with positive stride can overflow when in a + /// less-than comparison, knowing the invariant term of the comparison, + /// the stride and the knowledge of NSW/NUW flags on the recurrence. + bool doesIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride, + bool IsSigned, bool NoWrap); + + /// Verify if an linear IV with negative stride can overflow when in a + /// greater-than comparison, knowing the invariant term of the comparison, + /// the stride and the knowledge of NSW/NUW flags on the recurrence. + bool doesIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride, + bool IsSigned, bool NoWrap); private: FoldingSet UniqueSCEVs;