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llvm-6502/include/llvm/Analysis/ScalarEvolution.h
Dan Gohman c93b4cff89 Add the ability to "intern" FoldingSetNodeID data into a 
BumpPtrAllocator-allocated region to allow it to be stored in a more
compact form and to avoid the need for a non-trivial destructor call.

Use this new mechanism in ScalarEvolution instead of
FastFoldingSetNode to avoid leaking memory in the case where a
FoldingSetNodeID uses heap storage, and to reduce overall memory
usage.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98829 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-18 16:16:38 +00:00

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//===- llvm/Analysis/ScalarEvolution.h - Scalar Evolution -------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// The ScalarEvolution class is an LLVM pass which can be used to analyze and
// categorize scalar expressions in loops. It specializes in recognizing
// general induction variables, representing them with the abstract and opaque
// SCEV class. Given this analysis, trip counts of loops and other important
// properties can be obtained.
//
// This analysis is primarily useful for induction variable substitution and
// strength reduction.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_H
#define LLVM_ANALYSIS_SCALAREVOLUTION_H
#include "llvm/Pass.h"
#include "llvm/Instructions.h"
#include "llvm/Function.h"
#include "llvm/System/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 <map>
namespace llvm {
class APInt;
class Constant;
class ConstantInt;
class DominatorTree;
class Type;
class ScalarEvolution;
class TargetData;
class LLVMContext;
class Loop;
class LoopInfo;
class Operator;
/// SCEV - This class represents an analyzed expression in the program. These
/// are opaque objects that the client is not allowed to do much with
/// directly.
///
class SCEV : public FoldingSetNode {
/// FastID - A reference to an Interned FoldingSetNodeID for this node.
/// The ScalarEvolution's BumpPtrAllocator holds the data.
FoldingSetNodeIDRef FastID;
// The SCEV baseclass this node corresponds to
const unsigned short SCEVType;
protected:
/// SubclassData - This field is initialized to zero and may be used in
/// subclasses to store miscellaneous information.
unsigned short SubclassData;
private:
SCEV(const SCEV &); // DO NOT IMPLEMENT
void operator=(const SCEV &); // DO NOT IMPLEMENT
protected:
virtual ~SCEV();
public:
explicit SCEV(const FoldingSetNodeIDRef ID, unsigned SCEVTy) :
FastID(ID), SCEVType(SCEVTy), SubclassData(0) {}
unsigned getSCEVType() const { return SCEVType; }
/// Profile - FoldingSet support.
void Profile(FoldingSetNodeID& ID) { ID = FastID; }
/// isLoopInvariant - Return true if the value of this SCEV is unchanging in
/// the specified loop.
virtual bool isLoopInvariant(const Loop *L) const = 0;
/// hasComputableLoopEvolution - Return true if this SCEV changes value in a
/// known way in the specified loop. This property being true implies that
/// the value is variant in the loop AND that we can emit an expression to
/// compute the value of the expression at any particular loop iteration.
virtual bool hasComputableLoopEvolution(const Loop *L) const = 0;
/// getType - Return the LLVM type of this SCEV expression.
///
virtual const Type *getType() const = 0;
/// isZero - Return true if the expression is a constant zero.
///
bool isZero() const;
/// isOne - Return true if the expression is a constant one.
///
bool isOne() const;
/// isAllOnesValue - Return true if the expression is a constant
/// all-ones value.
///
bool isAllOnesValue() const;
/// hasOperand - Test whether this SCEV has Op as a direct or
/// indirect operand.
virtual bool hasOperand(const SCEV *Op) const = 0;
/// dominates - Return true if elements that makes up this SCEV dominates
/// the specified basic block.
virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const = 0;
/// properlyDominates - Return true if elements that makes up this SCEV
/// properly dominate the specified basic block.
virtual bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const = 0;
/// print - Print out the internal representation of this scalar to the
/// specified stream. This should really only be used for debugging
/// purposes.
virtual void print(raw_ostream &OS) const = 0;
/// dump - This method is used for debugging.
///
void dump() const;
};
inline raw_ostream &operator<<(raw_ostream &OS, const SCEV &S) {
S.print(OS);
return OS;
}
/// SCEVCouldNotCompute - An object of this class is returned by queries that
/// could not be answered. For example, if you ask for the number of
/// iterations of a linked-list traversal loop, you will get one of these.
/// None of the standard SCEV operations are valid on this class, it is just a
/// marker.
struct SCEVCouldNotCompute : public SCEV {
SCEVCouldNotCompute();
// None of these methods are valid for this object.
virtual bool isLoopInvariant(const Loop *L) const;
virtual const Type *getType() const;
virtual bool hasComputableLoopEvolution(const Loop *L) const;
virtual void print(raw_ostream &OS) const;
virtual bool hasOperand(const SCEV *Op) const;
virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const {
return true;
}
virtual bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
return true;
}
/// 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);
};
/// ScalarEvolution - This class is the main scalar evolution driver. Because
/// client code (intentionally) can't do much with the SCEV objects directly,
/// they must ask this class for services.
///
class ScalarEvolution : public FunctionPass {
/// SCEVCallbackVH - A CallbackVH to arrange for ScalarEvolution to be
/// notified whenever a Value is deleted.
class SCEVCallbackVH : public CallbackVH {
ScalarEvolution *SE;
virtual void deleted();
virtual void allUsesReplacedWith(Value *New);
public:
SCEVCallbackVH(Value *V, ScalarEvolution *SE = 0);
};
friend class SCEVCallbackVH;
friend class SCEVExpander;
/// F - The function we are analyzing.
///
Function *F;
/// LI - The loop information for the function we are currently analyzing.
///
LoopInfo *LI;
/// TD - The target data information for the target we are targeting.
///
TargetData *TD;
/// DT - The dominator tree.
///
DominatorTree *DT;
/// CouldNotCompute - This SCEV is used to represent unknown trip
/// counts and things.
SCEVCouldNotCompute CouldNotCompute;
/// Scalars - This is a cache of the scalars we have analyzed so far.
///
std::map<SCEVCallbackVH, const SCEV *> Scalars;
/// 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;
/// 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) {}
BackedgeTakenInfo(const SCEV *exact, const SCEV *max) :
Exact(exact), Max(max) {}
/// 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);
}
};
/// BackedgeTakenCounts - Cache the backedge-taken count of the loops for
/// this function as they are computed.
std::map<const Loop*, BackedgeTakenInfo> BackedgeTakenCounts;
/// ConstantEvolutionLoopExitValue - This map contains entries for all of
/// the PHI instructions that we attempt to compute constant evolutions for.
/// This allows us to avoid potentially expensive recomputation of these
/// properties. An instruction maps to null if we are unable to compute its
/// exit value.
std::map<PHINode*, Constant*> ConstantEvolutionLoopExitValue;
/// ValuesAtScopes - This map contains entries for all the expressions
/// that we attempt to compute getSCEVAtScope information for, which can
/// be expensive in extreme cases.
std::map<const SCEV *,
std::map<const Loop *, const SCEV *> > ValuesAtScopes;
/// createSCEV - We know that there is no SCEV for the specified value.
/// Analyze the expression.
const SCEV *createSCEV(Value *V);
/// createNodeForPHI - Provide the special handling we need to analyze PHI
/// SCEVs.
const SCEV *createNodeForPHI(PHINode *PN);
/// createNodeForGEP - Provide the special handling we need to analyze GEP
/// SCEVs.
const SCEV *createNodeForGEP(GEPOperator *GEP);
/// computeSCEVAtScope - Implementation code for getSCEVAtScope; called
/// at most once for each SCEV+Loop pair.
///
const SCEV *computeSCEVAtScope(const SCEV *S, const Loop *L);
/// ForgetSymbolicValue - This looks up computed SCEV values for all
/// instructions that depend on the given instruction and removes them from
/// the Scalars map if they reference SymName. This is used during PHI
/// 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.
const BackedgeTakenInfo &getBackedgeTakenInfo(const Loop *L);
/// ComputeBackedgeTakenCount - Compute the number of times the specified
/// 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
/// 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),
/// 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);
/// HowFarToZero - Return the number of times a backedge comparing the
/// specified value to zero will execute. If not computable, return
/// CouldNotCompute.
BackedgeTakenInfo HowFarToZero(const SCEV *V, const Loop *L);
/// HowFarToNonZero - Return the number of times a backedge checking the
/// specified value for nonzero will execute. If not computable, return
/// CouldNotCompute.
BackedgeTakenInfo 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);
/// getLoopPredecessor - If the given loop's header has exactly one unique
/// predecessor outside the loop, return it. Otherwise return null.
BasicBlock *getLoopPredecessor(const Loop *L);
/// getPredecessorWithUniqueSuccessorForBB - Return a predecessor of BB
/// (which may not be an immediate predecessor) which has exactly one
/// successor from which BB is reachable, or null if no such block is
/// found.
BasicBlock* getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB);
/// isImpliedCond - Test whether the condition described by Pred, LHS,
/// and RHS is true whenever the given Cond value evaluates to true.
bool isImpliedCond(Value *Cond, ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS,
bool Inverse);
/// isImpliedCondOperands - Test whether the condition described by Pred,
/// LHS, and RHS is true whenever the condition described by Pred, FoundLHS,
/// and FoundRHS is true.
bool isImpliedCondOperands(ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS,
const SCEV *FoundLHS, const SCEV *FoundRHS);
/// isImpliedCondOperandsHelper - Test whether the condition described by
/// Pred, LHS, and RHS is true whenever the condition described by Pred,
/// FoundLHS, and FoundRHS is true.
bool isImpliedCondOperandsHelper(ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS,
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
/// constant number of times, and the PHI node is just a recurrence
/// involving constants, fold it.
Constant *getConstantEvolutionLoopExitValue(PHINode *PN, const APInt& BEs,
const Loop *L);
public:
static char ID; // Pass identification, replacement for typeid
ScalarEvolution();
LLVMContext &getContext() const { return F->getContext(); }
/// isSCEVable - Test if values of the given type are analyzable within
/// the SCEV framework. This primarily includes integer types, and it
/// can optionally include pointer types if the ScalarEvolution class
/// has access to target-specific information.
bool isSCEVable(const Type *Ty) const;
/// getTypeSizeInBits - Return the size in bits of the specified type,
/// for which isSCEVable must return true.
uint64_t getTypeSizeInBits(const Type *Ty) const;
/// getEffectiveSCEVType - Return a type with the same bitwidth as
/// the given type and which represents how SCEV will treat the given
/// type, for which isSCEVable must return true. For pointer types,
/// this is the pointer-sized integer type.
const Type *getEffectiveSCEVType(const Type *Ty) const;
/// getSCEV - Return a SCEV expression for the full generality of the
/// specified expression.
const SCEV *getSCEV(Value *V);
const SCEV *getConstant(ConstantInt *V);
const SCEV *getConstant(const APInt& Val);
const SCEV *getConstant(const Type *Ty, uint64_t V, bool isSigned = false);
const SCEV *getTruncateExpr(const SCEV *Op, const Type *Ty);
const SCEV *getZeroExtendExpr(const SCEV *Op, const Type *Ty);
const SCEV *getSignExtendExpr(const SCEV *Op, const Type *Ty);
const SCEV *getAnyExtendExpr(const SCEV *Op, const Type *Ty);
const SCEV *getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
bool HasNUW = false, bool HasNSW = false);
const SCEV *getAddExpr(const SCEV *LHS, const SCEV *RHS,
bool HasNUW = false, bool HasNSW = false) {
SmallVector<const SCEV *, 2> Ops;
Ops.push_back(LHS);
Ops.push_back(RHS);
return getAddExpr(Ops, HasNUW, HasNSW);
}
const SCEV *getAddExpr(const SCEV *Op0, const SCEV *Op1,
const SCEV *Op2,
bool HasNUW = false, bool HasNSW = false) {
SmallVector<const SCEV *, 3> Ops;
Ops.push_back(Op0);
Ops.push_back(Op1);
Ops.push_back(Op2);
return getAddExpr(Ops, HasNUW, HasNSW);
}
const SCEV *getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
bool HasNUW = false, bool HasNSW = false);
const SCEV *getMulExpr(const SCEV *LHS, const SCEV *RHS,
bool HasNUW = false, bool HasNSW = false) {
SmallVector<const SCEV *, 2> Ops;
Ops.push_back(LHS);
Ops.push_back(RHS);
return getMulExpr(Ops, HasNUW, HasNSW);
}
const SCEV *getUDivExpr(const SCEV *LHS, const SCEV *RHS);
const SCEV *getAddRecExpr(const SCEV *Start, const SCEV *Step,
const Loop *L,
bool HasNUW = false, bool HasNSW = false);
const SCEV *getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
const Loop *L,
bool HasNUW = false, bool HasNSW = false);
const SCEV *getAddRecExpr(const SmallVectorImpl<const SCEV *> &Operands,
const Loop *L,
bool HasNUW = false, bool HasNSW = false) {
SmallVector<const SCEV *, 4> NewOp(Operands.begin(), Operands.end());
return getAddRecExpr(NewOp, L, HasNUW, HasNSW);
}
const SCEV *getSMaxExpr(const SCEV *LHS, const SCEV *RHS);
const SCEV *getSMaxExpr(SmallVectorImpl<const SCEV *> &Operands);
const SCEV *getUMaxExpr(const SCEV *LHS, const SCEV *RHS);
const SCEV *getUMaxExpr(SmallVectorImpl<const SCEV *> &Operands);
const SCEV *getSMinExpr(const SCEV *LHS, const SCEV *RHS);
const SCEV *getUMinExpr(const SCEV *LHS, const SCEV *RHS);
const SCEV *getUnknown(Value *V);
const SCEV *getCouldNotCompute();
/// getSizeOfExpr - Return an expression for sizeof on the given type.
///
const SCEV *getSizeOfExpr(const Type *AllocTy);
/// getAlignOfExpr - Return an expression for alignof on the given type.
///
const SCEV *getAlignOfExpr(const Type *AllocTy);
/// getOffsetOfExpr - Return an expression for offsetof on the given field.
///
const SCEV *getOffsetOfExpr(const StructType *STy, unsigned FieldNo);
/// getOffsetOfExpr - Return an expression for offsetof on the given field.
///
const SCEV *getOffsetOfExpr(const Type *CTy, Constant *FieldNo);
/// getNegativeSCEV - Return the SCEV object corresponding to -V.
///
const SCEV *getNegativeSCEV(const SCEV *V);
/// getNotSCEV - Return the SCEV object corresponding to ~V.
///
const SCEV *getNotSCEV(const SCEV *V);
/// getMinusSCEV - Return LHS-RHS.
///
const SCEV *getMinusSCEV(const SCEV *LHS,
const SCEV *RHS);
/// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion
/// of the input value to the specified type. If the type must be
/// extended, it is zero extended.
const SCEV *getTruncateOrZeroExtend(const SCEV *V, const Type *Ty);
/// getTruncateOrSignExtend - Return a SCEV corresponding to a conversion
/// of the input value to the specified type. If the type must be
/// extended, it is sign extended.
const SCEV *getTruncateOrSignExtend(const SCEV *V, const Type *Ty);
/// getNoopOrZeroExtend - Return a SCEV corresponding to a conversion of
/// the input value to the specified type. If the type must be extended,
/// it is zero extended. The conversion must not be narrowing.
const SCEV *getNoopOrZeroExtend(const SCEV *V, const Type *Ty);
/// getNoopOrSignExtend - Return a SCEV corresponding to a conversion of
/// the input value to the specified type. If the type must be extended,
/// it is sign extended. The conversion must not be narrowing.
const SCEV *getNoopOrSignExtend(const SCEV *V, const Type *Ty);
/// getNoopOrAnyExtend - Return a SCEV corresponding to a conversion of
/// the input value to the specified type. If the type must be extended,
/// it is extended with unspecified bits. The conversion must not be
/// narrowing.
const SCEV *getNoopOrAnyExtend(const SCEV *V, const Type *Ty);
/// getTruncateOrNoop - Return a SCEV corresponding to a conversion of the
/// input value to the specified type. The conversion must not be
/// widening.
const SCEV *getTruncateOrNoop(const SCEV *V, const Type *Ty);
/// getIntegerSCEV - Given a SCEVable type, create a constant for the
/// specified signed integer value and return a SCEV for the constant.
const SCEV *getIntegerSCEV(int64_t Val, const Type *Ty);
/// getUMaxFromMismatchedTypes - Promote the operands to the wider of
/// the types using zero-extension, and then perform a umax operation
/// with them.
const SCEV *getUMaxFromMismatchedTypes(const SCEV *LHS,
const SCEV *RHS);
/// getUMinFromMismatchedTypes - Promote the operands to the wider of
/// the types using zero-extension, and then perform a umin operation
/// with them.
const SCEV *getUMinFromMismatchedTypes(const SCEV *LHS,
const SCEV *RHS);
/// getSCEVAtScope - Return a SCEV expression for the specified value
/// at the specified scope in the program. The L value specifies a loop
/// nest to evaluate the expression at, where null is the top-level or a
/// specified loop is immediately inside of the loop.
///
/// This method can be used to compute the exit value for a variable defined
/// in a loop by querying what the value will hold in the parent loop.
///
/// In the case that a relevant loop exit value cannot be computed, the
/// original value V is returned.
const SCEV *getSCEVAtScope(const SCEV *S, const Loop *L);
/// getSCEVAtScope - This is a convenience function which does
/// getSCEVAtScope(getSCEV(V), L).
const SCEV *getSCEVAtScope(Value *V, const Loop *L);
/// isLoopGuardedByCond - Test whether entry to the loop is protected by
/// a conditional between LHS and RHS. This is used to help avoid max
/// expressions in loop trip counts, and to eliminate casts.
bool isLoopGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS);
/// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is
/// protected by a conditional between LHS and RHS. This is used to
/// to eliminate casts.
bool isLoopBackedgeGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS);
/// 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
/// will be branched to from within the loop. This is one less than the
/// trip count of the loop, since it doesn't count the first iteration,
/// when the header is branched to from outside the loop.
///
/// Note that it is not valid to call this method on a loop without a
/// loop-invariant backedge-taken count (see
/// hasLoopInvariantBackedgeTakenCount).
///
const SCEV *getBackedgeTakenCount(const Loop *L);
/// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except
/// return the least SCEV value that is known never to be less than the
/// actual backedge taken count.
const SCEV *getMaxBackedgeTakenCount(const Loop *L);
/// hasLoopInvariantBackedgeTakenCount - Return true if the specified loop
/// has an analyzable loop-invariant backedge-taken count.
bool hasLoopInvariantBackedgeTakenCount(const Loop *L);
/// 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.
void forgetLoop(const Loop *L);
/// forgetValue - This method should be called by the client when it has
/// changed a value in a way that may effect its value, or which may
/// disconnect it from a def-use chain linking it to a loop.
void forgetValue(Value *V);
/// 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,
/// given {4,+,8} it returns 2. If S is guaranteed to be 0, it returns the
/// bitwidth of S.
uint32_t GetMinTrailingZeros(const SCEV *S);
/// getUnsignedRange - Determine the unsigned range for a particular SCEV.
///
ConstantRange getUnsignedRange(const SCEV *S);
/// getSignedRange - Determine the signed range for a particular SCEV.
///
ConstantRange getSignedRange(const SCEV *S);
/// isKnownNegative - Test if the given expression is known to be negative.
///
bool isKnownNegative(const SCEV *S);
/// isKnownPositive - Test if the given expression is known to be positive.
///
bool isKnownPositive(const SCEV *S);
/// isKnownNonNegative - Test if the given expression is known to be
/// non-negative.
///
bool isKnownNonNegative(const SCEV *S);
/// isKnownNonPositive - Test if the given expression is known to be
/// non-positive.
///
bool isKnownNonPositive(const SCEV *S);
/// isKnownNonZero - Test if the given expression is known to be
/// non-zero.
///
bool isKnownNonZero(const SCEV *S);
/// isKnownNonZero - Test if the given expression is known to satisfy
/// the condition described by Pred, LHS, and RHS.
///
bool isKnownPredicate(ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS);
virtual bool runOnFunction(Function &F);
virtual void releaseMemory();
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
virtual void print(raw_ostream &OS, const Module* = 0) const;
private:
FoldingSet<SCEV> UniqueSCEVs;
BumpPtrAllocator SCEVAllocator;
};
}
#endif
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