#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 <map>
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;
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.
/// operator. NSW is a misnomer that we use to mean no signed overflow or
/// underflow.
///
- /// AddRec expression may have a no-self-wraparound <NW> 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 <NW> 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 <NW>. <NW> 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
///
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
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) {
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);
};
/// 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);
}
/// 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;
///
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.
///
///
ValueExprMapType ValueExprMap;
+ /// Mark predicate values currently being processed by isImpliedCond.
+ DenseSet<Value*> 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<SCEVCouldNotCompute>(Exact) ||
+ !isa<SCEVCouldNotCompute>(Max);
+ }
+ };
+
+ /// ExitNotTakenInfo - Information about the number of times a particular
+ /// loop exit may be reached before exiting the loop.
+ struct ExitNotTakenInfo {
+ AssertingVH<BasicBlock> ExitingBlock;
+ const SCEV *ExactNotTaken;
+ PointerIntPair<ExitNotTakenInfo*, 1> 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<BasicBlock *, const SCEV *> > &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<SCEVCouldNotCompute>(Exact) ||
- !isa<SCEVCouldNotCompute>(Max);
+ return ExitNotTaken.ExitingBlock || !isa<SCEVCouldNotCompute>(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
/// that we attempt to compute getSCEVAtScope information for, which can
/// be expensive in extreme cases.
DenseMap<const SCEV *,
- std::map<const Loop *, const SCEV *> > ValuesAtScopes;
+ SmallVector<std::pair<const Loop *, const SCEV *>, 2> > ValuesAtScopes;
/// LoopDispositions - Memoized computeLoopDisposition results.
DenseMap<const SCEV *,
- std::map<const Loop *, LoopDisposition> > LoopDispositions;
+ SmallVector<PointerIntPair<const Loop *, 2, LoopDisposition>, 2>>
+ LoopDispositions;
/// computeLoopDisposition - Compute a LoopDisposition value.
LoopDisposition computeLoopDisposition(const SCEV *S, const Loop *L);
/// BlockDispositions - Memoized computeBlockDisposition results.
- DenseMap<const SCEV *,
- std::map<const BasicBlock *, BlockDisposition> > BlockDispositions;
+ DenseMap<
+ const SCEV *,
+ SmallVector<PointerIntPair<const BasicBlock *, 2, BlockDisposition>, 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<const SCEV *, ConstantRange> UnsignedRanges;
- /// SignedRanges - Memoized results from getSignedRange
+ /// SignedRanges - Memoized results from getRange
DenseMap<const SCEV *, ConstantRange> SignedRanges;
- /// setUnsignedRange - Set the memoized unsigned range for the given SCEV.
- const ConstantRange &setUnsignedRange(const SCEV *S,
- const ConstantRange &CR) {
- std::pair<DenseMap<const SCEV *, ConstantRange>::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<const SCEV *, ConstantRange> &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<DenseMap<const SCEV *, ConstantRange>::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);
/// 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.
/// 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
/// 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
/// 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<typename ExtendOpTy>
+ bool proveNoWrapByVaryingStart(const SCEV *Start, const SCEV *Step,
+ const Loop *L);
+
public:
static char ID; // Pass identification, replacement for typeid
ScalarEvolution();
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<const SCEV *, 3> 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<const SCEV *> &Operands,
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.
///
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
/// 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
/// 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,
/// 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.
///
/// 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.
/// 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<const SCEV *> &Terms,
+ SmallVectorImpl<const SCEV *> &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<SCEV> UniqueSCEVs;
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