//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// 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
-// catagorize scalar expressions in loops. It specializes in recognizing
+// 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.
#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_H
#define LLVM_ANALYSIS_SCALAREVOLUTION_H
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/FoldingSet.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Operator.h"
#include "llvm/Pass.h"
+#include "llvm/Support/Allocator.h"
+#include "llvm/Support/ConstantRange.h"
#include "llvm/Support/DataTypes.h"
-#include "llvm/Support/Streams.h"
-#include <set>
+#include "llvm/Support/ValueHandle.h"
+#include <map>
namespace llvm {
- class Instruction;
+ class APInt;
+ class Constant;
+ class ConstantInt;
+ class DominatorTree;
class Type;
- class ConstantRange;
+ class ScalarEvolution;
+ class DataLayout;
+ class TargetLibraryInfo;
+ class LLVMContext;
class Loop;
class LoopInfo;
- class SCEVHandle;
-
- /// SCEV - This class represent an analyzed expression in the program. These
- /// are reference counted opaque objects that the client is not allowed to
- /// do much with directly.
+ class Operator;
+ class SCEVUnknown;
+ class SCEV;
+ template<> struct FoldingSetTrait<SCEV>;
+
+ /// 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 {
- const unsigned SCEVType; // The SCEV baseclass this node corresponds to
- mutable unsigned RefCount;
-
- friend class SCEVHandle;
- void addRef() const { ++RefCount; }
- void dropRef() const {
- if (--RefCount == 0)
- delete this;
- }
+ class SCEV : public FoldingSetNode {
+ friend struct FoldingSetTrait<SCEV>;
+
+ /// 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;
- SCEV(const SCEV &); // DO NOT IMPLEMENT
- void operator=(const SCEV &); // DO NOT IMPLEMENT
protected:
- virtual ~SCEV();
- public:
- SCEV(unsigned SCEVTy) : SCEVType(SCEVTy), RefCount(0) {}
+ /// SubclassData - This field is initialized to zero and may be used in
+ /// subclasses to store miscellaneous information.
+ unsigned short SubclassData;
- /// getNegativeSCEV - Return the SCEV object corresponding to -V.
- ///
- static SCEVHandle getNegativeSCEV(const SCEVHandle &V);
+ private:
+ SCEV(const SCEV &) LLVM_DELETED_FUNCTION;
+ void operator=(const SCEV &) LLVM_DELETED_FUNCTION;
- /// getMinusSCEV - Return LHS-RHS.
+ public:
+ /// NoWrapFlags are bitfield indices into SubclassData.
///
- static SCEVHandle getMinusSCEV(const SCEVHandle &LHS,
- const SCEVHandle &RHS);
-
+ /// Add and Mul expressions may have no-unsigned-wrap <NUW> or
+ /// no-signed-wrap <NSW> properties, which are derived from the IR
+ /// operator. NSW is a misnomer that we use to mean no signed overflow or
+ /// underflow.
+ ///
+ /// AddRec expression may have a no-self-wraparound <NW> property if the
+ /// result can never reach the start value. This property is independent of
+ /// the actual start value and step direction. Self-wraparound is defined
+ /// purely in terms of the recurrence's loop, step size, and
+ /// bitwidth. Formally, a recurrence with no self-wraparound satisfies:
+ /// abs(step) * max-iteration(loop) <= unsigned-max(bitwidth).
+ ///
+ /// Note that NUW and NSW are also valid properties of a recurrence, and
+ /// either implies NW. For convenience, NW will be set for a recurrence
+ /// whenever either NUW or NSW are set.
+ enum NoWrapFlags { FlagAnyWrap = 0, // No guarantee.
+ FlagNW = (1 << 0), // No self-wrap.
+ FlagNUW = (1 << 1), // No unsigned wrap.
+ FlagNSW = (1 << 2), // No signed wrap.
+ NoWrapMask = (1 << 3) -1 };
+
+ explicit SCEV(const FoldingSetNodeIDRef ID, unsigned SCEVTy) :
+ FastID(ID), SCEVType(SCEVTy), SubclassData(0) {}
unsigned getSCEVType() const { return SCEVType; }
- /// getValueRange - Return the tightest constant bounds that this value is
- /// known to have. This method is only valid on integer SCEV objects.
- virtual ConstantRange getValueRange() const;
-
- /// isLoopInvariant - Return true if the value of this SCEV is unchanging in
- /// the specified loop.
- virtual bool isLoopInvariant(const Loop *L) const = 0;
+ /// getType - Return the LLVM type of this SCEV expression.
+ ///
+ Type *getType() const;
- /// 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;
+ /// isZero - Return true if the expression is a constant zero.
+ ///
+ bool isZero() const;
- /// getType - Return the LLVM type of this SCEV expression.
+ /// isOne - Return true if the expression is a constant one.
///
- virtual const Type *getType() const = 0;
+ bool isOne() const;
- /// getBitWidth - Get the bit width of the type, if it has one, 0 otherwise.
- ///
- uint32_t getBitWidth() const;
+ /// isAllOnesValue - Return true if the expression is a constant
+ /// all-ones value.
+ ///
+ bool isAllOnesValue() const;
- /// replaceSymbolicValuesWithConcrete - If this SCEV internally references
- /// the symbolic value "Sym", construct and return a new SCEV that produces
- /// the same value, but which uses the concrete value Conc instead of the
- /// symbolic value. If this SCEV does not use the symbolic value, it
- /// returns itself.
- virtual SCEVHandle
- replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
- const SCEVHandle &Conc) const = 0;
+ /// isNonConstantNegative - Return true if the specified scev is negated,
+ /// but not a constant.
+ bool isNonConstantNegative() const;
/// print - Print out the internal representation of this scalar to the
/// specified stream. This should really only be used for debugging
/// purposes.
- virtual void print(std::ostream &OS) const = 0;
- void print(std::ostream *OS) const { if (OS) print(*OS); }
+ void print(raw_ostream &OS) const;
/// dump - This method is used for debugging.
///
void dump() const;
};
- inline std::ostream &operator<<(std::ostream &OS, const SCEV &S) {
+ // Specialize FoldingSetTrait for SCEV to avoid needing to compute
+ // temporary FoldingSetNodeID values.
+ template<> struct FoldingSetTrait<SCEV> : DefaultFoldingSetTrait<SCEV> {
+ static void Profile(const SCEV &X, FoldingSetNodeID& ID) {
+ ID = X.FastID;
+ }
+ static bool Equals(const SCEV &X, const FoldingSetNodeID &ID,
+ unsigned IDHash, FoldingSetNodeID &TempID) {
+ return ID == X.FastID;
+ }
+ static unsigned ComputeHash(const SCEV &X, FoldingSetNodeID &TempID) {
+ return X.FastID.ComputeHash();
+ }
+ };
+
+ inline raw_ostream &operator<<(raw_ostream &OS, const SCEV &S) {
S.print(OS);
return OS;
}
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(std::ostream &OS) const;
- void print(std::ostream *OS) const { if (OS) print(*OS); }
- virtual SCEVHandle
- replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
- const SCEVHandle &Conc) const;
-
/// 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);
};
- /// SCEVHandle - This class is used to maintain the SCEV object's refcounts,
- /// freeing the objects when the last reference is dropped.
- class SCEVHandle {
- SCEV *S;
- SCEVHandle(); // DO NOT IMPLEMENT
+ /// 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 {
public:
- SCEVHandle(const SCEV *s) : S(const_cast<SCEV*>(s)) {
- assert(S && "Cannot create a handle to a null SCEV!");
- S->addRef();
+ /// LoopDisposition - An enum describing the relationship between a
+ /// SCEV and a loop.
+ enum LoopDisposition {
+ LoopVariant, ///< The SCEV is loop-variant (unknown).
+ LoopInvariant, ///< The SCEV is loop-invariant.
+ LoopComputable ///< The SCEV varies predictably with the loop.
+ };
+
+ /// BlockDisposition - An enum describing the relationship between a
+ /// SCEV and a basic block.
+ enum BlockDisposition {
+ DoesNotDominateBlock, ///< The SCEV does not dominate the block.
+ DominatesBlock, ///< The SCEV dominates the block.
+ ProperlyDominatesBlock ///< The SCEV properly dominates the block.
+ };
+
+ /// Convenient NoWrapFlags manipulation that hides enum casts and is
+ /// visible in the ScalarEvolution name space.
+ static SCEV::NoWrapFlags maskFlags(SCEV::NoWrapFlags Flags, int Mask) {
+ return (SCEV::NoWrapFlags)(Flags & Mask);
+ }
+ static SCEV::NoWrapFlags setFlags(SCEV::NoWrapFlags Flags,
+ SCEV::NoWrapFlags OnFlags) {
+ return (SCEV::NoWrapFlags)(Flags | OnFlags);
}
- SCEVHandle(const SCEVHandle &RHS) : S(RHS.S) {
- S->addRef();
+ static SCEV::NoWrapFlags clearFlags(SCEV::NoWrapFlags Flags,
+ SCEV::NoWrapFlags OffFlags) {
+ return (SCEV::NoWrapFlags)(Flags & ~OffFlags);
}
- ~SCEVHandle() { S->dropRef(); }
- operator SCEV*() const { return S; }
+ private:
+ /// 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;
+ friend class SCEVUnknown;
+
+ /// 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.
+ ///
+ DataLayout *TD;
+
+ /// TLI - The target library information for the target we are targeting.
+ ///
+ TargetLibraryInfo *TLI;
+
+ /// DT - The dominator tree.
+ ///
+ DominatorTree *DT;
+
+ /// CouldNotCompute - This SCEV is used to represent unknown trip
+ /// counts and things.
+ SCEVCouldNotCompute CouldNotCompute;
+
+ /// ValueExprMapType - The typedef for ValueExprMap.
+ ///
+ typedef DenseMap<SCEVCallbackVH, const SCEV *, DenseMapInfo<Value *> >
+ ValueExprMapType;
+
+ /// ValueExprMap - This is a cache of the values we have analyzed so far.
+ ///
+ ValueExprMapType ValueExprMap;
- SCEV &operator*() const { return *S; }
- SCEV *operator->() const { return S; }
+ /// Mark predicate values currently being processed by isImpliedCond.
+ DenseSet<Value*> PendingLoopPredicates;
- bool operator==(SCEV *RHS) const { return S == RHS; }
- bool operator!=(SCEV *RHS) const { return S != RHS; }
+ /// ExitLimit - Information about the number of loop iterations for
+ /// which a loop exit's branch condition evaluates to the not-taken path.
+ /// This is a temporary pair of exact and max expressions that are
+ /// eventually summarized in ExitNotTakenInfo and BackedgeTakenInfo.
+ struct ExitLimit {
+ const SCEV *Exact;
+ const SCEV *Max;
- const SCEVHandle &operator=(SCEV *RHS) {
- if (S != RHS) {
- S->dropRef();
- S = RHS;
- S->addRef();
+ /*implicit*/ ExitLimit(const SCEV *E) : Exact(E), Max(E) {}
+
+ ExitLimit(const SCEV *E, const SCEV *M) : Exact(E), Max(M) {}
+
+ /// hasAnyInfo - Test whether this ExitLimit contains any computed
+ /// information, or whether it's all SCEVCouldNotCompute values.
+ bool hasAnyInfo() const {
+ return !isa<SCEVCouldNotCompute>(Exact) ||
+ !isa<SCEVCouldNotCompute>(Max);
+ }
+ };
+
+ /// ExitNotTakenInfo - Information about the number of times a particular
+ /// loop exit may be reached before exiting the loop.
+ struct ExitNotTakenInfo {
+ AssertingVH<BasicBlock> ExitingBlock;
+ const SCEV *ExactNotTaken;
+ PointerIntPair<ExitNotTakenInfo*, 1> NextExit;
+
+ ExitNotTakenInfo() : ExitingBlock(0), ExactNotTaken(0) {}
+
+ /// isCompleteList - Return true if all loop exits are computable.
+ bool isCompleteList() const {
+ return NextExit.getInt() == 0;
}
- return *this;
- }
- const SCEVHandle &operator=(const SCEVHandle &RHS) {
- if (S != RHS.S) {
- S->dropRef();
- S = RHS.S;
- S->addRef();
+ void setIncomplete() { NextExit.setInt(1); }
+
+ /// getNextExit - Return a pointer to the next exit's not-taken info.
+ ExitNotTakenInfo *getNextExit() const {
+ return NextExit.getPointer();
}
- return *this;
+
+ void setNextExit(ExitNotTakenInfo *ENT) { NextExit.setPointer(ENT); }
+ };
+
+ /// BackedgeTakenInfo - Information about the backedge-taken count
+ /// of a loop. This currently includes an exact count and a maximum count.
+ ///
+ class BackedgeTakenInfo {
+ /// ExitNotTaken - A list of computable exits and their not-taken counts.
+ /// Loops almost never have more than one computable exit.
+ ExitNotTakenInfo ExitNotTaken;
+
+ /// Max - An expression indicating the least maximum backedge-taken
+ /// count of the loop that is known, or a SCEVCouldNotCompute.
+ const SCEV *Max;
+
+ public:
+ BackedgeTakenInfo() : Max(0) {}
+
+ /// Initialize BackedgeTakenInfo from a list of exact exit counts.
+ BackedgeTakenInfo(
+ SmallVectorImpl< std::pair<BasicBlock *, const SCEV *> > &ExitCounts,
+ bool Complete, const SCEV *MaxCount);
+
+ /// hasAnyInfo - Test whether this BackedgeTakenInfo contains any
+ /// computed information, or whether it's all SCEVCouldNotCompute
+ /// values.
+ bool hasAnyInfo() const {
+ return ExitNotTaken.ExitingBlock || !isa<SCEVCouldNotCompute>(Max);
+ }
+
+ /// getExact - Return an expression indicating the exact backedge-taken
+ /// count of the loop if it is known, or SCEVCouldNotCompute
+ /// otherwise. This is the number of times the loop header can be
+ /// guaranteed to execute, minus one.
+ const SCEV *getExact(ScalarEvolution *SE) const;
+
+ /// getExact - Return the number of times this loop exit may fall through
+ /// to the back edge, or SCEVCouldNotCompute. The loop is guaranteed not
+ /// to exit via this block before this number of iterations, but may exit
+ /// via another block.
+ const SCEV *getExact(BasicBlock *ExitingBlock, ScalarEvolution *SE) const;
+
+ /// getMax - Get the max backedge taken count for the loop.
+ const SCEV *getMax(ScalarEvolution *SE) const;
+
+ /// Return true if any backedge taken count expressions refer to the given
+ /// subexpression.
+ bool hasOperand(const SCEV *S, ScalarEvolution *SE) const;
+
+ /// clear - Invalidate this result and free associated memory.
+ void clear();
+ };
+
+ /// BackedgeTakenCounts - Cache the backedge-taken count of the loops for
+ /// this function as they are computed.
+ DenseMap<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.
+ DenseMap<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.
+ DenseMap<const SCEV *,
+ std::map<const Loop *, const SCEV *> > ValuesAtScopes;
+
+ /// LoopDispositions - Memoized computeLoopDisposition results.
+ DenseMap<const SCEV *,
+ std::map<const Loop *, LoopDisposition> > LoopDispositions;
+
+ /// computeLoopDisposition - Compute a LoopDisposition value.
+ LoopDisposition computeLoopDisposition(const SCEV *S, const Loop *L);
+
+ /// BlockDispositions - Memoized computeBlockDisposition results.
+ DenseMap<const SCEV *,
+ std::map<const BasicBlock *, BlockDisposition> > BlockDispositions;
+
+ /// computeBlockDisposition - Compute a BlockDisposition value.
+ BlockDisposition computeBlockDisposition(const SCEV *S, const BasicBlock *BB);
+
+ /// UnsignedRanges - Memoized results from getUnsignedRange
+ DenseMap<const SCEV *, ConstantRange> UnsignedRanges;
+
+ /// SignedRanges - Memoized results from getSignedRange
+ DenseMap<const SCEV *, ConstantRange> SignedRanges;
+
+ /// setUnsignedRange - Set the memoized unsigned range for the given SCEV.
+ const ConstantRange &setUnsignedRange(const SCEV *S,
+ const ConstantRange &CR) {
+ std::pair<DenseMap<const SCEV *, ConstantRange>::iterator, bool> Pair =
+ UnsignedRanges.insert(std::make_pair(S, CR));
+ if (!Pair.second)
+ Pair.first->second = CR;
+ return Pair.first->second;
}
- };
- template<typename From> struct simplify_type;
- template<> struct simplify_type<const SCEVHandle> {
- typedef SCEV* SimpleType;
- static SimpleType getSimplifiedValue(const SCEVHandle &Node) {
- return Node;
+ /// setUnsignedRange - Set the memoized signed range for the given SCEV.
+ const ConstantRange &setSignedRange(const SCEV *S,
+ const ConstantRange &CR) {
+ std::pair<DenseMap<const SCEV *, ConstantRange>::iterator, bool> Pair =
+ SignedRanges.insert(std::make_pair(S, CR));
+ if (!Pair.second)
+ Pair.first->second = CR;
+ return Pair.first->second;
}
- };
- template<> struct simplify_type<SCEVHandle>
- : public simplify_type<const SCEVHandle> {};
- /// 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 {
- void *Impl; // ScalarEvolution uses the pimpl pattern
+ /// 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 ValueExprMap 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);
+
+ /// ComputeExitLimit - Compute the number of times the backedge of the
+ /// specified loop will execute if it exits via the specified block.
+ ExitLimit ComputeExitLimit(const Loop *L, BasicBlock *ExitingBlock);
+
+ /// ComputeExitLimitFromCond - Compute the number of times the backedge of
+ /// the specified loop will execute if its exit condition were a conditional
+ /// branch of ExitCond, TBB, and FBB.
+ ExitLimit ComputeExitLimitFromCond(const Loop *L,
+ Value *ExitCond,
+ BasicBlock *TBB,
+ BasicBlock *FBB,
+ bool IsSubExpr);
+
+ /// ComputeExitLimitFromICmp - Compute the number of times the backedge of
+ /// the specified loop will execute if its exit condition were a conditional
+ /// branch of the ICmpInst ExitCond, TBB, and FBB.
+ ExitLimit ComputeExitLimitFromICmp(const Loop *L,
+ ICmpInst *ExitCond,
+ BasicBlock *TBB,
+ BasicBlock *FBB,
+ bool IsSubExpr);
+
+ /// ComputeLoadConstantCompareExitLimit - Given an exit condition
+ /// of 'icmp op load X, cst', try to see if we can compute the
+ /// backedge-taken count.
+ ExitLimit ComputeLoadConstantCompareExitLimit(LoadInst *LI,
+ Constant *RHS,
+ const Loop *L,
+ ICmpInst::Predicate p);
+
+ /// ComputeExitCountExhaustively - If the loop is known to execute a
+ /// constant number of times (the condition evolves only from constants),
+ /// try to evaluate a few iterations of the loop until we get the exit
+ /// condition gets a value of ExitWhen (true or false). If we cannot
+ /// evaluate the exit count of the loop, return CouldNotCompute.
+ const SCEV *ComputeExitCountExhaustively(const Loop *L,
+ Value *Cond,
+ bool ExitWhen);
+
+ /// HowFarToZero - Return the number of times an exit condition comparing
+ /// the specified value to zero will execute. If not computable, return
+ /// CouldNotCompute.
+ ExitLimit HowFarToZero(const SCEV *V, const Loop *L, bool IsSubExpr);
+
+ /// HowFarToNonZero - Return the number of times an exit condition checking
+ /// the specified value for nonzero will execute. If not computable, return
+ /// CouldNotCompute.
+ ExitLimit HowFarToNonZero(const SCEV *V, const Loop *L);
+
+ /// HowManyLessThans - Return the number of times an exit condition
+ /// containing the specified less-than comparison will execute. If not
+ /// computable, return CouldNotCompute. isSigned specifies whether the
+ /// less-than is signed.
+ ExitLimit HowManyLessThans(const SCEV *LHS, const SCEV *RHS,
+ const Loop *L, bool isSigned, bool IsSubExpr);
+
+ /// 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.
+ std::pair<BasicBlock *, BasicBlock *>
+ getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB);
+
+ /// isImpliedCond - Test whether the condition described by Pred, LHS, and
+ /// RHS is true whenever the given FoundCondValue value evaluates to true.
+ bool isImpliedCond(ICmpInst::Predicate Pred,
+ const SCEV *LHS, const SCEV *RHS,
+ Value *FoundCondValue,
+ 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);
+
+ /// isKnownPredicateWithRanges - Test if the given expression is known to
+ /// satisfy the condition described by Pred and the known constant ranges
+ /// of LHS and RHS.
+ ///
+ bool isKnownPredicateWithRanges(ICmpInst::Predicate Pred,
+ const SCEV *LHS, const SCEV *RHS);
+
+ /// forgetMemoizedResults - Drop memoized information computed for S.
+ void forgetMemoizedResults(const SCEV *S);
+
public:
- static const char ID; // Pass identifcation, replacement for typeid
- ScalarEvolution() : FunctionPass((intptr_t)&ID), Impl(0) {}
+ 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(Type *Ty) const;
- /// getSCEV - Return a SCEV expression handle for the full generality of the
+ /// getTypeSizeInBits - Return the size in bits of the specified type,
+ /// for which isSCEVable must return true.
+ uint64_t getTypeSizeInBits(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.
+ Type *getEffectiveSCEVType(Type *Ty) const;
+
+ /// getSCEV - Return a SCEV expression for the full generality of the
/// specified expression.
- SCEVHandle getSCEV(Value *V) const;
+ const SCEV *getSCEV(Value *V);
+
+ const SCEV *getConstant(ConstantInt *V);
+ const SCEV *getConstant(const APInt& Val);
+ const SCEV *getConstant(Type *Ty, uint64_t V, bool isSigned = false);
+ const SCEV *getTruncateExpr(const SCEV *Op, Type *Ty);
+ const SCEV *getZeroExtendExpr(const SCEV *Op, Type *Ty);
+ const SCEV *getSignExtendExpr(const SCEV *Op, Type *Ty);
+ const SCEV *getAnyExtendExpr(const SCEV *Op, Type *Ty);
+ const SCEV *getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
+ SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap);
+ const SCEV *getAddExpr(const SCEV *LHS, const SCEV *RHS,
+ SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap) {
+ SmallVector<const SCEV *, 2> Ops;
+ Ops.push_back(LHS);
+ Ops.push_back(RHS);
+ return getAddExpr(Ops, Flags);
+ }
+ const SCEV *getAddExpr(const SCEV *Op0, const SCEV *Op1, const SCEV *Op2,
+ SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap) {
+ SmallVector<const SCEV *, 3> Ops;
+ Ops.push_back(Op0);
+ Ops.push_back(Op1);
+ Ops.push_back(Op2);
+ return getAddExpr(Ops, Flags);
+ }
+ const SCEV *getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
+ SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap);
+ const SCEV *getMulExpr(const SCEV *LHS, const SCEV *RHS,
+ SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap)
+ {
+ SmallVector<const SCEV *, 2> Ops;
+ Ops.push_back(LHS);
+ Ops.push_back(RHS);
+ return getMulExpr(Ops, Flags);
+ }
+ const SCEV *getMulExpr(const SCEV *Op0, const SCEV *Op1, const SCEV *Op2,
+ SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap) {
+ SmallVector<const SCEV *, 3> Ops;
+ Ops.push_back(Op0);
+ Ops.push_back(Op1);
+ Ops.push_back(Op2);
+ return getMulExpr(Ops, Flags);
+ }
+ const SCEV *getUDivExpr(const SCEV *LHS, const SCEV *RHS);
+ const SCEV *getAddRecExpr(const SCEV *Start, const SCEV *Step,
+ const Loop *L, SCEV::NoWrapFlags Flags);
+ const SCEV *getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
+ const Loop *L, SCEV::NoWrapFlags Flags);
+ const SCEV *getAddRecExpr(const SmallVectorImpl<const SCEV *> &Operands,
+ const Loop *L, SCEV::NoWrapFlags Flags) {
+ SmallVector<const SCEV *, 4> NewOp(Operands.begin(), Operands.end());
+ return getAddRecExpr(NewOp, L, Flags);
+ }
+ 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(Type *AllocTy);
- /// hasSCEV - Return true if the SCEV for this value has already been
- /// computed.
- bool hasSCEV(Value *V) const;
+ /// getAlignOfExpr - Return an expression for alignof on the given type.
+ ///
+ const SCEV *getAlignOfExpr(Type *AllocTy);
- /// setSCEV - Insert the specified SCEV into the map of current SCEVs for
- /// the specified value.
- void setSCEV(Value *V, const SCEVHandle &H);
+ /// getOffsetOfExpr - Return an expression for offsetof on the given field.
+ ///
+ const SCEV *getOffsetOfExpr(StructType *STy, unsigned FieldNo);
- /// getSCEVAtScope - Return a SCEV expression handle for the specified value
+ /// getOffsetOfExpr - Return an expression for offsetof on the given field.
+ ///
+ const SCEV *getOffsetOfExpr(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. Minus is represented in SCEV as A+B*-1.
+ const SCEV *getMinusSCEV(const SCEV *LHS, const SCEV *RHS,
+ SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap);
+
+ /// 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, 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, 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, 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, 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, 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, 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);
+
+ /// getPointerBase - Transitively follow the chain of pointer-type operands
+ /// until reaching a SCEV that does not have a single pointer operand. This
+ /// returns a SCEVUnknown pointer for well-formed pointer-type expressions,
+ /// but corner cases do exist.
+ const SCEV *getPointerBase(const SCEV *V);
+
+ /// 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.
///
- /// If this value is not computable at this scope, a SCEVCouldNotCompute
- /// object is returned.
- SCEVHandle getSCEVAtScope(Value *V, const Loop *L) const;
+ /// 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);
+
+ /// isLoopEntryGuardedByCond - 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 isLoopEntryGuardedByCond(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);
+
+ /// getSmallConstantTripCount - Returns the maximum trip count of this loop
+ /// as a normal unsigned value. Returns 0 if the trip count is unknown or
+ /// not constant. This "trip count" assumes that control exits via
+ /// ExitingBlock. More precisely, it is the number of times that control may
+ /// reach ExitingBlock before taking the branch. For loops with multiple
+ /// exits, it may not be the number times that the loop header executes if
+ /// the loop exits prematurely via another branch.
+ unsigned getSmallConstantTripCount(Loop *L, BasicBlock *ExitingBlock);
+
+ /// getSmallConstantTripMultiple - Returns the largest constant divisor of
+ /// the trip count of this loop as a normal unsigned value, if
+ /// possible. This means that the actual trip count is always a multiple of
+ /// the returned value (don't forget the trip count could very well be zero
+ /// as well!). As explained in the comments for getSmallConstantTripCount,
+ /// this assumes that control exits the loop via ExitingBlock.
+ unsigned getSmallConstantTripMultiple(Loop *L, BasicBlock *ExitingBlock);
+
+ // getExitCount - Get the expression for the number of loop iterations for
+ // which this loop is guaranteed not to exit via ExitingBlock. Otherwise
+ // return SCEVCouldNotCompute.
+ const SCEV *getExitCount(Loop *L, BasicBlock *ExitingBlock);
+
+ /// getBackedgeTakenCount - If the specified loop has a predictable
+ /// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute
+ /// object. The backedge-taken count is the number of times the loop header
+ /// 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);
+
+ /// isKnownPredicate - 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);
+
+ /// SimplifyICmpOperands - Simplify LHS and RHS in a comparison with
+ /// predicate Pred. Return true iff any changes were made. If the
+ /// operands are provably equal or unequal, LHS and RHS are set to
+ /// the same value and Pred is set to either ICMP_EQ or ICMP_NE.
+ ///
+ bool SimplifyICmpOperands(ICmpInst::Predicate &Pred,
+ const SCEV *&LHS,
+ const SCEV *&RHS,
+ unsigned Depth = 0);
- /// getIterationCount - If the specified loop has a predictable iteration
- /// count, return it, otherwise return a SCEVCouldNotCompute object.
- SCEVHandle getIterationCount(const Loop *L) const;
+ /// getLoopDisposition - Return the "disposition" of the given SCEV with
+ /// respect to the given loop.
+ LoopDisposition getLoopDisposition(const SCEV *S, const Loop *L);
- /// hasLoopInvariantIterationCount - Return true if the specified loop has
- /// an analyzable loop-invariant iteration count.
- bool hasLoopInvariantIterationCount(const Loop *L) const;
+ /// isLoopInvariant - Return true if the value of the given SCEV is
+ /// unchanging in the specified loop.
+ bool isLoopInvariant(const SCEV *S, const Loop *L);
- /// deleteInstructionFromRecords - This method should be called by the
- /// client before it removes an instruction from the program, to make sure
- /// that no dangling references are left around.
- void deleteInstructionFromRecords(Instruction *I) const;
+ /// hasComputableLoopEvolution - Return true if the given 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.
+ bool hasComputableLoopEvolution(const SCEV *S, const Loop *L);
+
+ /// getLoopDisposition - Return the "disposition" of the given SCEV with
+ /// respect to the given block.
+ BlockDisposition getBlockDisposition(const SCEV *S, const BasicBlock *BB);
+
+ /// dominates - Return true if elements that makes up the given SCEV
+ /// dominate the specified basic block.
+ bool dominates(const SCEV *S, const BasicBlock *BB);
+
+ /// properlyDominates - Return true if elements that makes up the given SCEV
+ /// properly dominate the specified basic block.
+ bool properlyDominates(const SCEV *S, const BasicBlock *BB);
+
+ /// hasOperand - Test whether the given SCEV has Op as a direct or
+ /// indirect operand.
+ bool hasOperand(const SCEV *S, const SCEV *Op) const;
virtual bool runOnFunction(Function &F);
virtual void releaseMemory();
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
- virtual void print(std::ostream &OS, const Module* = 0) const;
- void print(std::ostream *OS, const Module* M = 0) const {
- if (OS) print(*OS, M);
- }
+ virtual void print(raw_ostream &OS, const Module* = 0) const;
+ virtual void verifyAnalysis() const;
+
+ private:
+ FoldingSet<SCEV> UniqueSCEVs;
+ BumpPtrAllocator SCEVAllocator;
+
+ /// FirstUnknown - The head of a linked list of all SCEVUnknown
+ /// values that have been allocated. This is used by releaseMemory
+ /// to locate them all and call their destructors.
+ SCEVUnknown *FirstUnknown;
};
}
projects / oota-llvm.git / blobdiff