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blocks, and also exit blocks with multiple conditions (combined with (bitwise) ands and ors). It's often infeasible to compute an exact trip count in such cases, but a useful upper bound can often be found. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73866 91177308-0d34-0410-b5e6-96231b3b80d8
638 lines
26 KiB
C++
638 lines
26 KiB
C++
//===- llvm/Analysis/ScalarEvolution.h - Scalar Evolution -------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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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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//===----------------------------------------------------------------------===//
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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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// catagorize 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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//
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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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//===----------------------------------------------------------------------===//
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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/Analysis/LoopInfo.h"
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#include "llvm/Support/DataTypes.h"
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#include "llvm/Support/ValueHandle.h"
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#include "llvm/ADT/DenseMap.h"
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#include <iosfwd>
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namespace llvm {
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class APInt;
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class ConstantInt;
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class Type;
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class SCEVHandle;
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class ScalarEvolution;
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class TargetData;
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template<> struct DenseMapInfo<SCEVHandle>;
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/// SCEV - This class represents an analyzed expression in the program. These
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/// are reference-counted opaque objects that the client is not allowed to
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/// do much with directly.
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///
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class SCEV {
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const unsigned SCEVType; // The SCEV baseclass this node corresponds to
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mutable unsigned RefCount;
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friend class SCEVHandle;
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friend class DenseMapInfo<SCEVHandle>;
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void addRef() const { ++RefCount; }
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void dropRef() const {
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if (--RefCount == 0)
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delete this;
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}
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const ScalarEvolution* parent;
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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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protected:
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virtual ~SCEV();
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public:
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explicit SCEV(unsigned SCEVTy, const ScalarEvolution* p) :
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SCEVType(SCEVTy), RefCount(0), parent(p) {}
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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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///
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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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///
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bool isZero() const;
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/// isOne - Return true if the expression is a constant one.
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///
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bool isOne() const;
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/// replaceSymbolicValuesWithConcrete - If this SCEV internally references
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/// the symbolic value "Sym", construct and return a new SCEV that produces
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/// the same value, but which uses the concrete value Conc instead of the
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/// symbolic value. If this SCEV does not use the symbolic value, it
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/// returns itself.
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virtual SCEVHandle
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replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
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const SCEVHandle &Conc,
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ScalarEvolution &SE) 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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/// 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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/// purposes.
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virtual void print(raw_ostream &OS) const = 0;
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void print(std::ostream &OS) const;
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void print(std::ostream *OS) const { if (OS) print(*OS); }
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/// dump - This method is used for debugging.
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///
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void dump() const;
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};
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inline raw_ostream &operator<<(raw_ostream &OS, const SCEV &S) {
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S.print(OS);
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return OS;
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}
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inline std::ostream &operator<<(std::ostream &OS, const SCEV &S) {
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S.print(OS);
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return OS;
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}
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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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/// marker.
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struct SCEVCouldNotCompute : public SCEV {
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SCEVCouldNotCompute(const ScalarEvolution* p);
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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 SCEVHandle
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replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
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const SCEVHandle &Conc,
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ScalarEvolution &SE) const;
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virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const {
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return true;
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}
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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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};
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/// SCEVHandle - This class is used to maintain the SCEV object's refcounts,
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/// freeing the objects when the last reference is dropped.
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class SCEVHandle {
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const SCEV *S;
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SCEVHandle(); // DO NOT IMPLEMENT
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public:
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SCEVHandle(const SCEV *s) : S(s) {
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assert(S && "Cannot create a handle to a null SCEV!");
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S->addRef();
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}
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SCEVHandle(const SCEVHandle &RHS) : S(RHS.S) {
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S->addRef();
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}
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~SCEVHandle() { S->dropRef(); }
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operator const SCEV*() const { return S; }
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const SCEV &operator*() const { return *S; }
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const SCEV *operator->() const { return S; }
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bool operator==(const SCEV *RHS) const { return S == RHS; }
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bool operator!=(const SCEV *RHS) const { return S != RHS; }
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const SCEVHandle &operator=(SCEV *RHS) {
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if (S != RHS) {
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S->dropRef();
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S = RHS;
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S->addRef();
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}
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return *this;
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}
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const SCEVHandle &operator=(const SCEVHandle &RHS) {
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if (S != RHS.S) {
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S->dropRef();
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S = RHS.S;
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S->addRef();
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}
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return *this;
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}
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};
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template<typename From> struct simplify_type;
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template<> struct simplify_type<const SCEVHandle> {
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typedef const SCEV* SimpleType;
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static SimpleType getSimplifiedValue(const SCEVHandle &Node) {
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return Node;
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}
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};
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template<> struct simplify_type<SCEVHandle>
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: public simplify_type<const SCEVHandle> {};
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// Specialize DenseMapInfo for SCEVHandle so that SCEVHandle may be used
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// as a key in DenseMaps.
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template<>
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struct DenseMapInfo<SCEVHandle> {
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static inline SCEVHandle getEmptyKey() {
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static SCEVCouldNotCompute Empty(0);
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if (Empty.RefCount == 0)
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Empty.addRef();
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return &Empty;
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}
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static inline SCEVHandle getTombstoneKey() {
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static SCEVCouldNotCompute Tombstone(0);
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if (Tombstone.RefCount == 0)
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Tombstone.addRef();
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return &Tombstone;
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}
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static unsigned getHashValue(const SCEVHandle &Val) {
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return DenseMapInfo<const SCEV *>::getHashValue(Val);
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}
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static bool isEqual(const SCEVHandle &LHS, const SCEVHandle &RHS) {
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return LHS == RHS;
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}
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static bool isPod() { return false; }
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};
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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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///
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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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ScalarEvolution *SE;
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virtual void deleted();
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virtual void allUsesReplacedWith(Value *New);
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public:
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SCEVCallbackVH(Value *V, ScalarEvolution *SE = 0);
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};
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friend class SCEVCallbackVH;
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friend class SCEVExpander;
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/// F - The function we are analyzing.
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///
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Function *F;
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/// LI - The loop information for the function we are currently analyzing.
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///
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LoopInfo *LI;
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/// TD - The target data information for the target we are targetting.
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///
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TargetData *TD;
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/// CouldNotCompute - This SCEV is used to represent unknown trip
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/// counts and things.
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SCEVHandle CouldNotCompute;
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/// Scalars - This is a cache of the scalars we have analyzed so far.
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///
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std::map<SCEVCallbackVH, SCEVHandle> Scalars;
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/// BackedgeTakenInfo - Information about the backedge-taken count
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/// of a loop. This currently inclues an exact count and a maximum count.
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///
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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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SCEVHandle Exact;
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/// Exact - 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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SCEVHandle Max;
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/*implicit*/ BackedgeTakenInfo(SCEVHandle exact) :
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Exact(exact), Max(exact) {}
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/*implicit*/ BackedgeTakenInfo(const SCEV *exact) :
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Exact(exact), Max(exact) {}
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BackedgeTakenInfo(SCEVHandle exact, SCEVHandle 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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/// values.
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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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}
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};
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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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/// exit value.
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std::map<PHINode*, Constant*> ConstantEvolutionLoopExitValue;
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/// ValuesAtScopes - This map contains entries for all the instructions
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/// that we attempt to compute getSCEVAtScope information for without
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/// using SCEV techniques, which can be expensive.
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std::map<Instruction *, std::map<const Loop *, Constant *> > 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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SCEVHandle createSCEV(Value *V);
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/// createNodeForPHI - Provide the special handling we need to analyze PHI
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/// SCEVs.
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SCEVHandle createNodeForPHI(PHINode *PN);
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/// createNodeForGEP - Provide the special handling we need to analyze GEP
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/// SCEVs.
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SCEVHandle createNodeForGEP(User *GEP);
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/// ReplaceSymbolicValueWithConcrete - This looks up the computed SCEV value
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/// for the specified instruction and replaces any references to the
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/// symbolic value SymName with the specified value. This is used during
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/// PHI resolution.
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void ReplaceSymbolicValueWithConcrete(Instruction *I,
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const SCEVHandle &SymName,
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const SCEVHandle &NewVal);
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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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SCEVHandle getBECount(const SCEVHandle &Start,
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const SCEVHandle &End,
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const SCEVHandle &Step);
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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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/// yet.
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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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/// specified block.
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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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BackedgeTakenInfo
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ComputeBackedgeTakenCountFromExitCond(const Loop *L,
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Value *ExitCond,
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BasicBlock *TBB,
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BasicBlock *FBB);
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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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/// and FBB.
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BackedgeTakenInfo
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ComputeBackedgeTakenCountFromExitCondICmp(const Loop *L,
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ICmpInst *ExitCond,
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BasicBlock *TBB,
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BasicBlock *FBB);
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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 trip count.
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SCEVHandle
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ComputeLoadConstantCompareBackedgeTakenCount(LoadInst *LI,
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Constant *RHS,
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const Loop *L,
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ICmpInst::Predicate p);
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/// ComputeBackedgeTakenCountExhaustively - If the trip 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 trip count of the loop, return CouldNotCompute.
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SCEVHandle ComputeBackedgeTakenCountExhaustively(const Loop *L, Value *Cond,
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bool ExitWhen);
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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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/// CouldNotCompute.
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SCEVHandle 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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/// CouldNotCompute.
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SCEVHandle 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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/// getLoopPredecessor - If the given loop's header has exactly one unique
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/// predecessor outside the loop, return it. Otherwise return null.
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BasicBlock *getLoopPredecessor(const Loop *L);
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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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/// found.
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BasicBlock* getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB);
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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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const Loop *L);
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/// forgetLoopPHIs - Delete the memoized SCEVs associated with the
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/// PHI nodes in the given loop. This is used when the trip count of
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/// the loop may have changed.
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void forgetLoopPHIs(const Loop *L);
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public:
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static char ID; // Pass identification, replacement for typeid
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ScalarEvolution();
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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 handle for the full generality of the
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/// specified expression.
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SCEVHandle getSCEV(Value *V);
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SCEVHandle getConstant(ConstantInt *V);
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SCEVHandle getConstant(const APInt& Val);
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SCEVHandle getConstant(const Type *Ty, uint64_t V, bool isSigned = false);
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SCEVHandle getTruncateExpr(const SCEVHandle &Op, const Type *Ty);
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SCEVHandle getZeroExtendExpr(const SCEVHandle &Op, const Type *Ty);
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SCEVHandle getSignExtendExpr(const SCEVHandle &Op, const Type *Ty);
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SCEVHandle getAnyExtendExpr(const SCEVHandle &Op, const Type *Ty);
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SCEVHandle getAddExpr(SmallVectorImpl<SCEVHandle> &Ops);
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SCEVHandle getAddExpr(const SCEVHandle &LHS, const SCEVHandle &RHS) {
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SmallVector<SCEVHandle, 2> Ops;
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Ops.push_back(LHS);
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Ops.push_back(RHS);
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return getAddExpr(Ops);
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}
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SCEVHandle getAddExpr(const SCEVHandle &Op0, const SCEVHandle &Op1,
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const SCEVHandle &Op2) {
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SmallVector<SCEVHandle, 3> Ops;
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Ops.push_back(Op0);
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|
Ops.push_back(Op1);
|
|
Ops.push_back(Op2);
|
|
return getAddExpr(Ops);
|
|
}
|
|
SCEVHandle getMulExpr(SmallVectorImpl<SCEVHandle> &Ops);
|
|
SCEVHandle getMulExpr(const SCEVHandle &LHS, const SCEVHandle &RHS) {
|
|
SmallVector<SCEVHandle, 2> Ops;
|
|
Ops.push_back(LHS);
|
|
Ops.push_back(RHS);
|
|
return getMulExpr(Ops);
|
|
}
|
|
SCEVHandle getUDivExpr(const SCEVHandle &LHS, const SCEVHandle &RHS);
|
|
SCEVHandle getAddRecExpr(const SCEVHandle &Start, const SCEVHandle &Step,
|
|
const Loop *L);
|
|
SCEVHandle getAddRecExpr(SmallVectorImpl<SCEVHandle> &Operands,
|
|
const Loop *L);
|
|
SCEVHandle getAddRecExpr(const SmallVectorImpl<SCEVHandle> &Operands,
|
|
const Loop *L) {
|
|
SmallVector<SCEVHandle, 4> NewOp(Operands.begin(), Operands.end());
|
|
return getAddRecExpr(NewOp, L);
|
|
}
|
|
SCEVHandle getSMaxExpr(const SCEVHandle &LHS, const SCEVHandle &RHS);
|
|
SCEVHandle getSMaxExpr(SmallVectorImpl<SCEVHandle> &Operands);
|
|
SCEVHandle getUMaxExpr(const SCEVHandle &LHS, const SCEVHandle &RHS);
|
|
SCEVHandle getUMaxExpr(SmallVectorImpl<SCEVHandle> &Operands);
|
|
SCEVHandle getUnknown(Value *V);
|
|
SCEVHandle getCouldNotCompute();
|
|
|
|
/// getNegativeSCEV - Return the SCEV object corresponding to -V.
|
|
///
|
|
SCEVHandle getNegativeSCEV(const SCEVHandle &V);
|
|
|
|
/// getNotSCEV - Return the SCEV object corresponding to ~V.
|
|
///
|
|
SCEVHandle getNotSCEV(const SCEVHandle &V);
|
|
|
|
/// getMinusSCEV - Return LHS-RHS.
|
|
///
|
|
SCEVHandle getMinusSCEV(const SCEVHandle &LHS,
|
|
const SCEVHandle &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.
|
|
SCEVHandle getTruncateOrZeroExtend(const SCEVHandle &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.
|
|
SCEVHandle getTruncateOrSignExtend(const SCEVHandle &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.
|
|
SCEVHandle getNoopOrZeroExtend(const SCEVHandle &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.
|
|
SCEVHandle getNoopOrSignExtend(const SCEVHandle &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.
|
|
SCEVHandle getNoopOrAnyExtend(const SCEVHandle &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.
|
|
SCEVHandle getTruncateOrNoop(const SCEVHandle &V, const Type *Ty);
|
|
|
|
/// getIntegerSCEV - Given an integer or FP type, create a constant for the
|
|
/// specified signed integer value and return a SCEV for the constant.
|
|
SCEVHandle getIntegerSCEV(int 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.
|
|
SCEVHandle getUMaxFromMismatchedTypes(const SCEVHandle &LHS,
|
|
const SCEVHandle &RHS);
|
|
|
|
/// hasSCEV - Return true if the SCEV for this value has already been
|
|
/// computed.
|
|
bool hasSCEV(Value *V) const;
|
|
|
|
/// setSCEV - Insert the specified SCEV into the map of current SCEVs for
|
|
/// the specified value.
|
|
void setSCEV(Value *V, const SCEVHandle &H);
|
|
|
|
/// getSCEVAtScope - Return a SCEV expression handle 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.
|
|
SCEVHandle getSCEVAtScope(const SCEV *S, const Loop *L);
|
|
|
|
/// getSCEVAtScope - This is a convenience function which does
|
|
/// getSCEVAtScope(getSCEV(V), L).
|
|
SCEVHandle 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.
|
|
bool isLoopGuardedByCond(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).
|
|
///
|
|
SCEVHandle 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.
|
|
SCEVHandle getMaxBackedgeTakenCount(const Loop *L);
|
|
|
|
/// hasLoopInvariantBackedgeTakenCount - Return true if the specified loop
|
|
/// has an analyzable loop-invariant backedge-taken count.
|
|
bool hasLoopInvariantBackedgeTakenCount(const Loop *L);
|
|
|
|
/// forgetLoopBackedgeTakenCount - 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 forgetLoopBackedgeTakenCount(const Loop *L);
|
|
|
|
/// 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 SCEVHandle &S);
|
|
|
|
/// GetMinLeadingZeros - Determine the minimum number of zero bits that S is
|
|
/// guaranteed to begin with (at every loop iteration).
|
|
uint32_t GetMinLeadingZeros(const SCEVHandle &S);
|
|
|
|
/// GetMinSignBits - Determine the minimum number of sign bits that S is
|
|
/// guaranteed to begin with.
|
|
uint32_t GetMinSignBits(const SCEVHandle &S);
|
|
|
|
virtual bool runOnFunction(Function &F);
|
|
virtual void releaseMemory();
|
|
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
|
|
void print(raw_ostream &OS, const Module* = 0) const;
|
|
virtual void print(std::ostream &OS, const Module* = 0) const;
|
|
void print(std::ostream *OS, const Module* M = 0) const {
|
|
if (OS) print(*OS, M);
|
|
}
|
|
};
|
|
}
|
|
|
|
#endif
|