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//===- llvm/Analysis/ScalarEvolution.h - Scalar Evolution -------*- C++ -*-===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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// The ScalarEvolution class is an LLVM pass which can be used to analyze and
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// categorize scalar expressions in loops. It specializes in recognizing
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// general induction variables, representing them with the abstract and opaque
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// SCEV class. Given this analysis, trip counts of loops and other important
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// properties can be obtained.
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// This analysis is primarily useful for induction variable substitution and
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// strength reduction.
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_H
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#define LLVM_ANALYSIS_SCALAREVOLUTION_H
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#include "llvm/Pass.h"
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#include "llvm/Instructions.h"
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#include "llvm/Function.h"
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#include "llvm/System/DataTypes.h"
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#include "llvm/Support/ValueHandle.h"
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#include "llvm/Support/Allocator.h"
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#include "llvm/Support/ConstantRange.h"
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#include "llvm/ADT/FoldingSet.h"
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#include "llvm/ADT/DenseMap.h"
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class ScalarEvolution;
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template<> struct FoldingSetTrait<SCEV>;
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/// SCEV - This class represents an analyzed expression in the program. These
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/// are opaque objects that the client is not allowed to do much with
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class SCEV : public FoldingSetNode {
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friend struct FoldingSetTrait<SCEV>;
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/// FastID - A reference to an Interned FoldingSetNodeID for this node.
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/// The ScalarEvolution's BumpPtrAllocator holds the data.
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FoldingSetNodeIDRef FastID;
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// The SCEV baseclass this node corresponds to
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const unsigned short SCEVType;
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/// SubclassData - This field is initialized to zero and may be used in
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/// subclasses to store miscellaneous information.
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unsigned short SubclassData;
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SCEV(const SCEV &); // DO NOT IMPLEMENT
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void operator=(const SCEV &); // DO NOT IMPLEMENT
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explicit SCEV(const FoldingSetNodeIDRef ID, unsigned SCEVTy) :
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FastID(ID), SCEVType(SCEVTy), SubclassData(0) {}
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unsigned getSCEVType() const { return SCEVType; }
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/// isLoopInvariant - Return true if the value of this SCEV is unchanging in
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/// the specified loop.
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virtual bool isLoopInvariant(const Loop *L) const = 0;
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/// hasComputableLoopEvolution - Return true if this SCEV changes value in a
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/// known way in the specified loop. This property being true implies that
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/// the value is variant in the loop AND that we can emit an expression to
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/// compute the value of the expression at any particular loop iteration.
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virtual bool hasComputableLoopEvolution(const Loop *L) const = 0;
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/// getType - Return the LLVM type of this SCEV expression.
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virtual const Type *getType() const = 0;
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/// isZero - Return true if the expression is a constant zero.
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/// isOne - Return true if the expression is a constant one.
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/// isAllOnesValue - Return true if the expression is a constant
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bool isAllOnesValue() const;
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/// hasOperand - Test whether this SCEV has Op as a direct or
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/// indirect operand.
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virtual bool hasOperand(const SCEV *Op) const = 0;
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/// dominates - Return true if elements that makes up this SCEV dominates
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/// the specified basic block.
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virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const = 0;
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/// properlyDominates - Return true if elements that makes up this SCEV
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/// properly dominate the specified basic block.
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virtual bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const = 0;
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/// print - Print out the internal representation of this scalar to the
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/// specified stream. This should really only be used for debugging
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virtual void print(raw_ostream &OS) const = 0;
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/// dump - This method is used for debugging.
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// Specialize FoldingSetTrait for SCEV to avoid needing to compute
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// temporary FoldingSetNodeID values.
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template<> struct FoldingSetTrait<SCEV> : DefaultFoldingSetTrait<SCEV> {
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static void Profile(const SCEV &X, FoldingSetNodeID& ID) {
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static bool Equals(const SCEV &X, const FoldingSetNodeID &ID,
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FoldingSetNodeID &TempID) {
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return ID == X.FastID;
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static unsigned ComputeHash(const SCEV &X, FoldingSetNodeID &TempID) {
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return X.FastID.ComputeHash();
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inline raw_ostream &operator<<(raw_ostream &OS, const SCEV &S) {
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/// SCEVCouldNotCompute - An object of this class is returned by queries that
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/// could not be answered. For example, if you ask for the number of
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/// iterations of a linked-list traversal loop, you will get one of these.
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/// None of the standard SCEV operations are valid on this class, it is just a
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struct SCEVCouldNotCompute : public SCEV {
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SCEVCouldNotCompute();
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// None of these methods are valid for this object.
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virtual bool isLoopInvariant(const Loop *L) const;
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virtual const Type *getType() const;
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virtual bool hasComputableLoopEvolution(const Loop *L) const;
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virtual void print(raw_ostream &OS) const;
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virtual bool hasOperand(const SCEV *Op) const;
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virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const {
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virtual bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
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/// Methods for support type inquiry through isa, cast, and dyn_cast:
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static inline bool classof(const SCEVCouldNotCompute *S) { return true; }
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static bool classof(const SCEV *S);
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/// ScalarEvolution - This class is the main scalar evolution driver. Because
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/// client code (intentionally) can't do much with the SCEV objects directly,
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/// they must ask this class for services.
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class ScalarEvolution : public FunctionPass {
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/// SCEVCallbackVH - A CallbackVH to arrange for ScalarEvolution to be
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/// notified whenever a Value is deleted.
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class SCEVCallbackVH : public CallbackVH {
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virtual void deleted();
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virtual void allUsesReplacedWith(Value *New);
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SCEVCallbackVH(Value *V, ScalarEvolution *SE = 0);
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friend class SCEVCallbackVH;
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friend class SCEVExpander;
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friend class SCEVUnknown;
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/// F - The function we are analyzing.
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/// LI - The loop information for the function we are currently analyzing.
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/// TD - The target data information for the target we are targeting.
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/// DT - The dominator tree.
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/// CouldNotCompute - This SCEV is used to represent unknown trip
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/// counts and things.
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SCEVCouldNotCompute CouldNotCompute;
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/// ValueExprMapType - The typedef for ValueExprMap.
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typedef DenseMap<SCEVCallbackVH, const SCEV *, DenseMapInfo<Value *> >
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/// ValueExprMap - This is a cache of the values we have analyzed so far.
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ValueExprMapType ValueExprMap;
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/// BackedgeTakenInfo - Information about the backedge-taken count
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/// of a loop. This currently includes an exact count and a maximum count.
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struct BackedgeTakenInfo {
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/// Exact - An expression indicating the exact backedge-taken count of
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/// the loop if it is known, or a SCEVCouldNotCompute otherwise.
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/// Max - An expression indicating the least maximum backedge-taken
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/// count of the loop that is known, or a SCEVCouldNotCompute.
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/*implicit*/ BackedgeTakenInfo(const SCEV *exact) :
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Exact(exact), Max(exact) {}
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BackedgeTakenInfo(const SCEV *exact, const SCEV *max) :
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Exact(exact), Max(max) {}
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/// hasAnyInfo - Test whether this BackedgeTakenInfo contains any
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/// computed information, or whether it's all SCEVCouldNotCompute
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bool hasAnyInfo() const {
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return !isa<SCEVCouldNotCompute>(Exact) ||
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!isa<SCEVCouldNotCompute>(Max);
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/// BackedgeTakenCounts - Cache the backedge-taken count of the loops for
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/// this function as they are computed.
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std::map<const Loop*, BackedgeTakenInfo> BackedgeTakenCounts;
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/// ConstantEvolutionLoopExitValue - This map contains entries for all of
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/// the PHI instructions that we attempt to compute constant evolutions for.
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/// This allows us to avoid potentially expensive recomputation of these
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/// properties. An instruction maps to null if we are unable to compute its
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std::map<PHINode*, Constant*> ConstantEvolutionLoopExitValue;
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/// ValuesAtScopes - This map contains entries for all the expressions
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/// that we attempt to compute getSCEVAtScope information for, which can
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/// be expensive in extreme cases.
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std::map<const SCEV *,
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std::map<const Loop *, const SCEV *> > ValuesAtScopes;
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/// createSCEV - We know that there is no SCEV for the specified value.
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/// Analyze the expression.
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const SCEV *createSCEV(Value *V);
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/// createNodeForPHI - Provide the special handling we need to analyze PHI
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const SCEV *createNodeForPHI(PHINode *PN);
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/// createNodeForGEP - Provide the special handling we need to analyze GEP
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const SCEV *createNodeForGEP(GEPOperator *GEP);
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/// computeSCEVAtScope - Implementation code for getSCEVAtScope; called
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/// at most once for each SCEV+Loop pair.
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const SCEV *computeSCEVAtScope(const SCEV *S, const Loop *L);
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/// ForgetSymbolicValue - This looks up computed SCEV values for all
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/// instructions that depend on the given instruction and removes them from
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/// the ValueExprMap map if they reference SymName. This is used during PHI
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void ForgetSymbolicName(Instruction *I, const SCEV *SymName);
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/// getBECount - Subtract the end and start values and divide by the step,
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/// rounding up, to get the number of times the backedge is executed. Return
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/// CouldNotCompute if an intermediate computation overflows.
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const SCEV *getBECount(const SCEV *Start,
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/// getBackedgeTakenInfo - Return the BackedgeTakenInfo for the given
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/// loop, lazily computing new values if the loop hasn't been analyzed
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const BackedgeTakenInfo &getBackedgeTakenInfo(const Loop *L);
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/// ComputeBackedgeTakenCount - Compute the number of times the specified
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/// loop will iterate.
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BackedgeTakenInfo ComputeBackedgeTakenCount(const Loop *L);
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/// ComputeBackedgeTakenCountFromExit - Compute the number of times the
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/// backedge of the specified loop will execute if it exits via the
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BackedgeTakenInfo ComputeBackedgeTakenCountFromExit(const Loop *L,
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BasicBlock *ExitingBlock);
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/// ComputeBackedgeTakenCountFromExitCond - Compute the number of times the
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/// backedge of the specified loop will execute if its exit condition
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/// were a conditional branch of ExitCond, TBB, and FBB.
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ComputeBackedgeTakenCountFromExitCond(const Loop *L,
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/// ComputeBackedgeTakenCountFromExitCondICmp - Compute the number of
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/// times the backedge of the specified loop will execute if its exit
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/// condition were a conditional branch of the ICmpInst ExitCond, TBB,
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ComputeBackedgeTakenCountFromExitCondICmp(const Loop *L,
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/// ComputeLoadConstantCompareBackedgeTakenCount - Given an exit condition
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/// of 'icmp op load X, cst', try to see if we can compute the
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/// backedge-taken count.
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ComputeLoadConstantCompareBackedgeTakenCount(LoadInst *LI,
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ICmpInst::Predicate p);
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/// ComputeBackedgeTakenCountExhaustively - If the loop is known to execute
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/// a constant number of times (the condition evolves only from constants),
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/// try to evaluate a few iterations of the loop until we get the exit
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/// condition gets a value of ExitWhen (true or false). If we cannot
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/// evaluate the backedge-taken count of the loop, return CouldNotCompute.
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const SCEV *ComputeBackedgeTakenCountExhaustively(const Loop *L,
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/// HowFarToZero - Return the number of times a backedge comparing the
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/// specified value to zero will execute. If not computable, return
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BackedgeTakenInfo HowFarToZero(const SCEV *V, const Loop *L);
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/// HowFarToNonZero - Return the number of times a backedge checking the
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/// specified value for nonzero will execute. If not computable, return
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BackedgeTakenInfo HowFarToNonZero(const SCEV *V, const Loop *L);
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/// HowManyLessThans - Return the number of times a backedge containing the
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/// specified less-than comparison will execute. If not computable, return
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/// CouldNotCompute. isSigned specifies whether the less-than is signed.
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BackedgeTakenInfo HowManyLessThans(const SCEV *LHS, const SCEV *RHS,
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const Loop *L, bool isSigned);
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/// getPredecessorWithUniqueSuccessorForBB - Return a predecessor of BB
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/// (which may not be an immediate predecessor) which has exactly one
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/// successor from which BB is reachable, or null if no such block is
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std::pair<BasicBlock *, BasicBlock *>
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getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB);
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/// isImpliedCond - Test whether the condition described by Pred, LHS, and
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/// RHS is true whenever the given FoundCondValue value evaluates to true.
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bool isImpliedCond(ICmpInst::Predicate Pred,
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const SCEV *LHS, const SCEV *RHS,
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Value *FoundCondValue,
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/// isImpliedCondOperands - Test whether the condition described by Pred,
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/// LHS, and RHS is true whenever the condition described by Pred, FoundLHS,
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/// and FoundRHS is true.
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bool isImpliedCondOperands(ICmpInst::Predicate Pred,
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const SCEV *LHS, const SCEV *RHS,
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const SCEV *FoundLHS, const SCEV *FoundRHS);
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/// isImpliedCondOperandsHelper - Test whether the condition described by
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/// Pred, LHS, and RHS is true whenever the condition described by Pred,
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/// FoundLHS, and FoundRHS is true.
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bool isImpliedCondOperandsHelper(ICmpInst::Predicate Pred,
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const SCEV *LHS, const SCEV *RHS,
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const SCEV *FoundLHS, const SCEV *FoundRHS);
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/// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
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/// in the header of its containing loop, we know the loop executes a
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/// constant number of times, and the PHI node is just a recurrence
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/// involving constants, fold it.
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Constant *getConstantEvolutionLoopExitValue(PHINode *PN, const APInt& BEs,
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/// isKnownPredicateWithRanges - Test if the given expression is known to
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/// satisfy the condition described by Pred and the known constant ranges
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bool isKnownPredicateWithRanges(ICmpInst::Predicate Pred,
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const SCEV *LHS, const SCEV *RHS);
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static char ID; // Pass identification, replacement for typeid
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LLVMContext &getContext() const { return F->getContext(); }
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/// isSCEVable - Test if values of the given type are analyzable within
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/// the SCEV framework. This primarily includes integer types, and it
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/// can optionally include pointer types if the ScalarEvolution class
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/// has access to target-specific information.
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bool isSCEVable(const Type *Ty) const;
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/// getTypeSizeInBits - Return the size in bits of the specified type,
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/// for which isSCEVable must return true.
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uint64_t getTypeSizeInBits(const Type *Ty) const;
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/// getEffectiveSCEVType - Return a type with the same bitwidth as
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/// the given type and which represents how SCEV will treat the given
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/// type, for which isSCEVable must return true. For pointer types,
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/// this is the pointer-sized integer type.
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const Type *getEffectiveSCEVType(const Type *Ty) const;
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/// getSCEV - Return a SCEV expression for the full generality of the
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/// specified expression.
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const SCEV *getSCEV(Value *V);
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const SCEV *getConstant(ConstantInt *V);
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const SCEV *getConstant(const APInt& Val);
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const SCEV *getConstant(const Type *Ty, uint64_t V, bool isSigned = false);
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const SCEV *getTruncateExpr(const SCEV *Op, const Type *Ty);
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const SCEV *getZeroExtendExpr(const SCEV *Op, const Type *Ty);
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const SCEV *getSignExtendExpr(const SCEV *Op, const Type *Ty);
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const SCEV *getAnyExtendExpr(const SCEV *Op, const Type *Ty);
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const SCEV *getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
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bool HasNUW = false, bool HasNSW = false);
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const SCEV *getAddExpr(const SCEV *LHS, const SCEV *RHS,
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bool HasNUW = false, bool HasNSW = false) {
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SmallVector<const SCEV *, 2> Ops;
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return getAddExpr(Ops, HasNUW, HasNSW);
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const SCEV *getAddExpr(const SCEV *Op0, const SCEV *Op1,
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bool HasNUW = false, bool HasNSW = false) {
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SmallVector<const SCEV *, 3> Ops;
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return getAddExpr(Ops, HasNUW, HasNSW);
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const SCEV *getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
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bool HasNUW = false, bool HasNSW = false);
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const SCEV *getMulExpr(const SCEV *LHS, const SCEV *RHS,
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bool HasNUW = false, bool HasNSW = false) {
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SmallVector<const SCEV *, 2> Ops;
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return getMulExpr(Ops, HasNUW, HasNSW);
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const SCEV *getUDivExpr(const SCEV *LHS, const SCEV *RHS);
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const SCEV *getAddRecExpr(const SCEV *Start, const SCEV *Step,
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bool HasNUW = false, bool HasNSW = false);
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const SCEV *getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
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bool HasNUW = false, bool HasNSW = false);
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const SCEV *getAddRecExpr(const SmallVectorImpl<const SCEV *> &Operands,
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bool HasNUW = false, bool HasNSW = false) {
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SmallVector<const SCEV *, 4> NewOp(Operands.begin(), Operands.end());
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return getAddRecExpr(NewOp, L, HasNUW, HasNSW);
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const SCEV *getSMaxExpr(const SCEV *LHS, const SCEV *RHS);
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const SCEV *getSMaxExpr(SmallVectorImpl<const SCEV *> &Operands);
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const SCEV *getUMaxExpr(const SCEV *LHS, const SCEV *RHS);
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const SCEV *getUMaxExpr(SmallVectorImpl<const SCEV *> &Operands);
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const SCEV *getSMinExpr(const SCEV *LHS, const SCEV *RHS);
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const SCEV *getUMinExpr(const SCEV *LHS, const SCEV *RHS);
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const SCEV *getUnknown(Value *V);
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const SCEV *getCouldNotCompute();
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/// getSizeOfExpr - Return an expression for sizeof on the given type.
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const SCEV *getSizeOfExpr(const Type *AllocTy);
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/// getAlignOfExpr - Return an expression for alignof on the given type.
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const SCEV *getAlignOfExpr(const Type *AllocTy);
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/// getOffsetOfExpr - Return an expression for offsetof on the given field.
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const SCEV *getOffsetOfExpr(const StructType *STy, unsigned FieldNo);
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/// getOffsetOfExpr - Return an expression for offsetof on the given field.
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const SCEV *getOffsetOfExpr(const Type *CTy, Constant *FieldNo);
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/// getNegativeSCEV - Return the SCEV object corresponding to -V.
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const SCEV *getNegativeSCEV(const SCEV *V);
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/// getNotSCEV - Return the SCEV object corresponding to ~V.
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const SCEV *getNotSCEV(const SCEV *V);
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/// getMinusSCEV - Return LHS-RHS.
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const SCEV *getMinusSCEV(const SCEV *LHS,
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/// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion
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/// of the input value to the specified type. If the type must be
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/// extended, it is zero extended.
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const SCEV *getTruncateOrZeroExtend(const SCEV *V, const Type *Ty);
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/// getTruncateOrSignExtend - Return a SCEV corresponding to a conversion
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/// of the input value to the specified type. If the type must be
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/// extended, it is sign extended.
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const SCEV *getTruncateOrSignExtend(const SCEV *V, const Type *Ty);
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/// getNoopOrZeroExtend - Return a SCEV corresponding to a conversion of
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/// the input value to the specified type. If the type must be extended,
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/// it is zero extended. The conversion must not be narrowing.
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const SCEV *getNoopOrZeroExtend(const SCEV *V, const Type *Ty);
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/// getNoopOrSignExtend - Return a SCEV corresponding to a conversion of
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/// the input value to the specified type. If the type must be extended,
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/// it is sign extended. The conversion must not be narrowing.
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const SCEV *getNoopOrSignExtend(const SCEV *V, const Type *Ty);
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/// getNoopOrAnyExtend - Return a SCEV corresponding to a conversion of
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/// the input value to the specified type. If the type must be extended,
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/// it is extended with unspecified bits. The conversion must not be
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const SCEV *getNoopOrAnyExtend(const SCEV *V, const Type *Ty);
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/// getTruncateOrNoop - Return a SCEV corresponding to a conversion of the
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/// input value to the specified type. The conversion must not be
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const SCEV *getTruncateOrNoop(const SCEV *V, const Type *Ty);
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/// getUMaxFromMismatchedTypes - Promote the operands to the wider of
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/// the types using zero-extension, and then perform a umax operation
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const SCEV *getUMaxFromMismatchedTypes(const SCEV *LHS,
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/// getUMinFromMismatchedTypes - Promote the operands to the wider of
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/// the types using zero-extension, and then perform a umin operation
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const SCEV *getUMinFromMismatchedTypes(const SCEV *LHS,
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/// getSCEVAtScope - Return a SCEV expression for the specified value
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/// at the specified scope in the program. The L value specifies a loop
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/// nest to evaluate the expression at, where null is the top-level or a
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/// specified loop is immediately inside of the loop.
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/// This method can be used to compute the exit value for a variable defined
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/// in a loop by querying what the value will hold in the parent loop.
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/// In the case that a relevant loop exit value cannot be computed, the
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/// original value V is returned.
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const SCEV *getSCEVAtScope(const SCEV *S, const Loop *L);
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/// getSCEVAtScope - This is a convenience function which does
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/// getSCEVAtScope(getSCEV(V), L).
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const SCEV *getSCEVAtScope(Value *V, const Loop *L);
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/// isLoopEntryGuardedByCond - Test whether entry to the loop is protected
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/// by a conditional between LHS and RHS. This is used to help avoid max
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/// expressions in loop trip counts, and to eliminate casts.
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bool isLoopEntryGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
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const SCEV *LHS, const SCEV *RHS);
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/// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is
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/// protected by a conditional between LHS and RHS. This is used to
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/// to eliminate casts.
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bool isLoopBackedgeGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
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const SCEV *LHS, const SCEV *RHS);
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/// getBackedgeTakenCount - If the specified loop has a predictable
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/// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute
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/// object. The backedge-taken count is the number of times the loop header
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/// will be branched to from within the loop. This is one less than the
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/// trip count of the loop, since it doesn't count the first iteration,
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/// when the header is branched to from outside the loop.
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/// Note that it is not valid to call this method on a loop without a
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/// loop-invariant backedge-taken count (see
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/// hasLoopInvariantBackedgeTakenCount).
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const SCEV *getBackedgeTakenCount(const Loop *L);
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/// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except
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/// return the least SCEV value that is known never to be less than the
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/// actual backedge taken count.
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const SCEV *getMaxBackedgeTakenCount(const Loop *L);
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/// hasLoopInvariantBackedgeTakenCount - Return true if the specified loop
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/// has an analyzable loop-invariant backedge-taken count.
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bool hasLoopInvariantBackedgeTakenCount(const Loop *L);
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/// forgetLoop - This method should be called by the client when it has
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/// changed a loop in a way that may effect ScalarEvolution's ability to
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/// compute a trip count, or if the loop is deleted.
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void forgetLoop(const Loop *L);
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/// forgetValue - This method should be called by the client when it has
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/// changed a value in a way that may effect its value, or which may
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/// disconnect it from a def-use chain linking it to a loop.
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void forgetValue(Value *V);
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/// GetMinTrailingZeros - Determine the minimum number of zero bits that S
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/// is guaranteed to end in (at every loop iteration). It is, at the same
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/// time, the minimum number of times S is divisible by 2. For example,
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/// given {4,+,8} it returns 2. If S is guaranteed to be 0, it returns the
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uint32_t GetMinTrailingZeros(const SCEV *S);
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/// getUnsignedRange - Determine the unsigned range for a particular SCEV.
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ConstantRange getUnsignedRange(const SCEV *S);
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/// getSignedRange - Determine the signed range for a particular SCEV.
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ConstantRange getSignedRange(const SCEV *S);
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/// isKnownNegative - Test if the given expression is known to be negative.
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bool isKnownNegative(const SCEV *S);
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/// isKnownPositive - Test if the given expression is known to be positive.
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bool isKnownPositive(const SCEV *S);
648
/// isKnownNonNegative - Test if the given expression is known to be
651
bool isKnownNonNegative(const SCEV *S);
653
/// isKnownNonPositive - Test if the given expression is known to be
656
bool isKnownNonPositive(const SCEV *S);
658
/// isKnownNonZero - Test if the given expression is known to be
661
bool isKnownNonZero(const SCEV *S);
663
/// isKnownPredicate - Test if the given expression is known to satisfy
664
/// the condition described by Pred, LHS, and RHS.
666
bool isKnownPredicate(ICmpInst::Predicate Pred,
667
const SCEV *LHS, const SCEV *RHS);
669
/// SimplifyICmpOperands - Simplify LHS and RHS in a comparison with
670
/// predicate Pred. Return true iff any changes were made. If the
671
/// operands are provably equal or inequal, LHS and RHS are set to
672
/// the same value and Pred is set to either ICMP_EQ or ICMP_NE.
674
bool SimplifyICmpOperands(ICmpInst::Predicate &Pred,
678
virtual bool runOnFunction(Function &F);
679
virtual void releaseMemory();
680
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
681
virtual void print(raw_ostream &OS, const Module* = 0) const;
684
FoldingSet<SCEV> UniqueSCEVs;
685
BumpPtrAllocator SCEVAllocator;
687
/// FirstUnknown - The head of a linked list of all SCEVUnknown
688
/// values that have been allocated. This is used by releaseMemory
689
/// to locate them all and call their destructors.
690
SCEVUnknown *FirstUnknown;