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diff --git a/contrib/llvm/include/llvm/Analysis/DependenceAnalysis.h b/contrib/llvm/include/llvm/Analysis/DependenceAnalysis.h new file mode 100644 index 000000000000..b4327eeb0b1e --- /dev/null +++ b/contrib/llvm/include/llvm/Analysis/DependenceAnalysis.h @@ -0,0 +1,885 @@ +//===-- llvm/Analysis/DependenceAnalysis.h -------------------- -*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// DependenceAnalysis is an LLVM pass that analyses dependences between memory +// accesses. Currently, it is an implementation of the approach described in +// +// Practical Dependence Testing +// Goff, Kennedy, Tseng +// PLDI 1991 +// +// There's a single entry point that analyzes the dependence between a pair +// of memory references in a function, returning either NULL, for no dependence, +// or a more-or-less detailed description of the dependence between them. +// +// Please note that this is work in progress and the interface is subject to +// change. +// +// Plausible changes: +// Return a set of more precise dependences instead of just one dependence +// summarizing all. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_ANALYSIS_DEPENDENCEANALYSIS_H +#define LLVM_ANALYSIS_DEPENDENCEANALYSIS_H + +#include "llvm/Instructions.h" +#include "llvm/Pass.h" +#include "llvm/ADT/SmallBitVector.h" + +namespace llvm { + class AliasAnalysis; + class Loop; + class LoopInfo; + class ScalarEvolution; + class SCEV; + class SCEVConstant; + class raw_ostream; + + /// Dependence - This class represents a dependence between two memory + /// memory references in a function. It contains minimal information and + /// is used in the very common situation where the compiler is unable to + /// determine anything beyond the existence of a dependence; that is, it + /// represents a confused dependence (see also FullDependence). In most + /// cases (for output, flow, and anti dependences), the dependence implies + /// an ordering, where the source must precede the destination; in contrast, + /// input dependences are unordered. + class Dependence { + public: + Dependence(const Instruction *Source, + const Instruction *Destination) : + Src(Source), Dst(Destination) {} + virtual ~Dependence() {} + + /// Dependence::DVEntry - Each level in the distance/direction vector + /// has a direction (or perhaps a union of several directions), and + /// perhaps a distance. + struct DVEntry { + enum { NONE = 0, + LT = 1, + EQ = 2, + LE = 3, + GT = 4, + NE = 5, + GE = 6, + ALL = 7 }; + unsigned char Direction : 3; // Init to ALL, then refine. + bool Scalar : 1; // Init to true. + bool PeelFirst : 1; // Peeling the first iteration will break dependence. + bool PeelLast : 1; // Peeling the last iteration will break the dependence. + bool Splitable : 1; // Splitting the loop will break dependence. + const SCEV *Distance; // NULL implies no distance available. + DVEntry() : Direction(ALL), Scalar(true), PeelFirst(false), + PeelLast(false), Splitable(false), Distance(NULL) { } + }; + + /// getSrc - Returns the source instruction for this dependence. + /// + const Instruction *getSrc() const { return Src; } + + /// getDst - Returns the destination instruction for this dependence. + /// + const Instruction *getDst() const { return Dst; } + + /// isInput - Returns true if this is an input dependence. + /// + bool isInput() const; + + /// isOutput - Returns true if this is an output dependence. + /// + bool isOutput() const; + + /// isFlow - Returns true if this is a flow (aka true) dependence. + /// + bool isFlow() const; + + /// isAnti - Returns true if this is an anti dependence. + /// + bool isAnti() const; + + /// isOrdered - Returns true if dependence is Output, Flow, or Anti + /// + bool isOrdered() const { return isOutput() || isFlow() || isAnti(); } + + /// isUnordered - Returns true if dependence is Input + /// + bool isUnordered() const { return isInput(); } + + /// isLoopIndependent - Returns true if this is a loop-independent + /// dependence. + virtual bool isLoopIndependent() const { return true; } + + /// isConfused - Returns true if this dependence is confused + /// (the compiler understands nothing and makes worst-case + /// assumptions). + virtual bool isConfused() const { return true; } + + /// isConsistent - Returns true if this dependence is consistent + /// (occurs every time the source and destination are executed). + virtual bool isConsistent() const { return false; } + + /// getLevels - Returns the number of common loops surrounding the + /// source and destination of the dependence. + virtual unsigned getLevels() const { return 0; } + + /// getDirection - Returns the direction associated with a particular + /// level. + virtual unsigned getDirection(unsigned Level) const { return DVEntry::ALL; } + + /// getDistance - Returns the distance (or NULL) associated with a + /// particular level. + virtual const SCEV *getDistance(unsigned Level) const { return NULL; } + + /// isPeelFirst - Returns true if peeling the first iteration from + /// this loop will break this dependence. + virtual bool isPeelFirst(unsigned Level) const { return false; } + + /// isPeelLast - Returns true if peeling the last iteration from + /// this loop will break this dependence. + virtual bool isPeelLast(unsigned Level) const { return false; } + + /// isSplitable - Returns true if splitting this loop will break + /// the dependence. + virtual bool isSplitable(unsigned Level) const { return false; } + + /// isScalar - Returns true if a particular level is scalar; that is, + /// if no subscript in the source or destination mention the induction + /// variable associated with the loop at this level. + virtual bool isScalar(unsigned Level) const; + + /// dump - For debugging purposes, dumps a dependence to OS. + /// + void dump(raw_ostream &OS) const; + private: + const Instruction *Src, *Dst; + friend class DependenceAnalysis; + }; + + + /// FullDependence - This class represents a dependence between two memory + /// references in a function. It contains detailed information about the + /// dependence (direction vectors, etc) and is used when the compiler is + /// able to accurately analyze the interaction of the references; that is, + /// it is not a confused dependence (see Dependence). In most cases + /// (for output, flow, and anti dependences), the dependence implies an + /// ordering, where the source must precede the destination; in contrast, + /// input dependences are unordered. + class FullDependence : public Dependence { + public: + FullDependence(const Instruction *Src, + const Instruction *Dst, + bool LoopIndependent, + unsigned Levels); + ~FullDependence() { + delete DV; + } + + /// isLoopIndependent - Returns true if this is a loop-independent + /// dependence. + bool isLoopIndependent() const { return LoopIndependent; } + + /// isConfused - Returns true if this dependence is confused + /// (the compiler understands nothing and makes worst-case + /// assumptions). + bool isConfused() const { return false; } + + /// isConsistent - Returns true if this dependence is consistent + /// (occurs every time the source and destination are executed). + bool isConsistent() const { return Consistent; } + + /// getLevels - Returns the number of common loops surrounding the + /// source and destination of the dependence. + unsigned getLevels() const { return Levels; } + + /// getDirection - Returns the direction associated with a particular + /// level. + unsigned getDirection(unsigned Level) const; + + /// getDistance - Returns the distance (or NULL) associated with a + /// particular level. + const SCEV *getDistance(unsigned Level) const; + + /// isPeelFirst - Returns true if peeling the first iteration from + /// this loop will break this dependence. + bool isPeelFirst(unsigned Level) const; + + /// isPeelLast - Returns true if peeling the last iteration from + /// this loop will break this dependence. + bool isPeelLast(unsigned Level) const; + + /// isSplitable - Returns true if splitting the loop will break + /// the dependence. + bool isSplitable(unsigned Level) const; + + /// isScalar - Returns true if a particular level is scalar; that is, + /// if no subscript in the source or destination mention the induction + /// variable associated with the loop at this level. + bool isScalar(unsigned Level) const; + private: + unsigned short Levels; + bool LoopIndependent; + bool Consistent; // Init to true, then refine. + DVEntry *DV; + friend class DependenceAnalysis; + }; + + + /// DependenceAnalysis - This class is the main dependence-analysis driver. + /// + class DependenceAnalysis : public FunctionPass { + void operator=(const DependenceAnalysis &); // do not implement + DependenceAnalysis(const DependenceAnalysis &); // do not implement + public: + /// depends - Tests for a dependence between the Src and Dst instructions. + /// Returns NULL if no dependence; otherwise, returns a Dependence (or a + /// FullDependence) with as much information as can be gleaned. + /// The flag PossiblyLoopIndependent should be set by the caller + /// if it appears that control flow can reach from Src to Dst + /// without traversing a loop back edge. + Dependence *depends(const Instruction *Src, + const Instruction *Dst, + bool PossiblyLoopIndependent); + + /// getSplitIteration - Give a dependence that's splitable at some + /// particular level, return the iteration that should be used to split + /// the loop. + /// + /// Generally, the dependence analyzer will be used to build + /// a dependence graph for a function (basically a map from instructions + /// to dependences). Looking for cycles in the graph shows us loops + /// that cannot be trivially vectorized/parallelized. + /// + /// We can try to improve the situation by examining all the dependences + /// that make up the cycle, looking for ones we can break. + /// Sometimes, peeling the first or last iteration of a loop will break + /// dependences, and there are flags for those possibilities. + /// Sometimes, splitting a loop at some other iteration will do the trick, + /// and we've got a flag for that case. Rather than waste the space to + /// record the exact iteration (since we rarely know), we provide + /// a method that calculates the iteration. It's a drag that it must work + /// from scratch, but wonderful in that it's possible. + /// + /// Here's an example: + /// + /// for (i = 0; i < 10; i++) + /// A[i] = ... + /// ... = A[11 - i] + /// + /// There's a loop-carried flow dependence from the store to the load, + /// found by the weak-crossing SIV test. The dependence will have a flag, + /// indicating that the dependence can be broken by splitting the loop. + /// Calling getSplitIteration will return 5. + /// Splitting the loop breaks the dependence, like so: + /// + /// for (i = 0; i <= 5; i++) + /// A[i] = ... + /// ... = A[11 - i] + /// for (i = 6; i < 10; i++) + /// A[i] = ... + /// ... = A[11 - i] + /// + /// breaks the dependence and allows us to vectorize/parallelize + /// both loops. + const SCEV *getSplitIteration(const Dependence *Dep, unsigned Level); + + private: + AliasAnalysis *AA; + ScalarEvolution *SE; + LoopInfo *LI; + Function *F; + + /// Subscript - This private struct represents a pair of subscripts from + /// a pair of potentially multi-dimensional array references. We use a + /// vector of them to guide subscript partitioning. + struct Subscript { + const SCEV *Src; + const SCEV *Dst; + enum ClassificationKind { ZIV, SIV, RDIV, MIV, NonLinear } Classification; + SmallBitVector Loops; + SmallBitVector GroupLoops; + SmallBitVector Group; + }; + + struct CoefficientInfo { + const SCEV *Coeff; + const SCEV *PosPart; + const SCEV *NegPart; + const SCEV *Iterations; + }; + + struct BoundInfo { + const SCEV *Iterations; + const SCEV *Upper[8]; + const SCEV *Lower[8]; + unsigned char Direction; + unsigned char DirSet; + }; + + /// Constraint - This private class represents a constraint, as defined + /// in the paper + /// + /// Practical Dependence Testing + /// Goff, Kennedy, Tseng + /// PLDI 1991 + /// + /// There are 5 kinds of constraint, in a hierarchy. + /// 1) Any - indicates no constraint, any dependence is possible. + /// 2) Line - A line ax + by = c, where a, b, and c are parameters, + /// representing the dependence equation. + /// 3) Distance - The value d of the dependence distance; + /// 4) Point - A point <x, y> representing the dependence from + /// iteration x to iteration y. + /// 5) Empty - No dependence is possible. + class Constraint { + private: + enum ConstraintKind { Empty, Point, Distance, Line, Any } Kind; + ScalarEvolution *SE; + const SCEV *A; + const SCEV *B; + const SCEV *C; + const Loop *AssociatedLoop; + public: + /// isEmpty - Return true if the constraint is of kind Empty. + bool isEmpty() const { return Kind == Empty; } + + /// isPoint - Return true if the constraint is of kind Point. + bool isPoint() const { return Kind == Point; } + + /// isDistance - Return true if the constraint is of kind Distance. + bool isDistance() const { return Kind == Distance; } + + /// isLine - Return true if the constraint is of kind Line. + /// Since Distance's can also be represented as Lines, we also return + /// true if the constraint is of kind Distance. + bool isLine() const { return Kind == Line || Kind == Distance; } + + /// isAny - Return true if the constraint is of kind Any; + bool isAny() const { return Kind == Any; } + + /// getX - If constraint is a point <X, Y>, returns X. + /// Otherwise assert. + const SCEV *getX() const; + + /// getY - If constraint is a point <X, Y>, returns Y. + /// Otherwise assert. + const SCEV *getY() const; + + /// getA - If constraint is a line AX + BY = C, returns A. + /// Otherwise assert. + const SCEV *getA() const; + + /// getB - If constraint is a line AX + BY = C, returns B. + /// Otherwise assert. + const SCEV *getB() const; + + /// getC - If constraint is a line AX + BY = C, returns C. + /// Otherwise assert. + const SCEV *getC() const; + + /// getD - If constraint is a distance, returns D. + /// Otherwise assert. + const SCEV *getD() const; + + /// getAssociatedLoop - Returns the loop associated with this constraint. + const Loop *getAssociatedLoop() const; + + /// setPoint - Change a constraint to Point. + void setPoint(const SCEV *X, const SCEV *Y, const Loop *CurrentLoop); + + /// setLine - Change a constraint to Line. + void setLine(const SCEV *A, const SCEV *B, + const SCEV *C, const Loop *CurrentLoop); + + /// setDistance - Change a constraint to Distance. + void setDistance(const SCEV *D, const Loop *CurrentLoop); + + /// setEmpty - Change a constraint to Empty. + void setEmpty(); + + /// setAny - Change a constraint to Any. + void setAny(ScalarEvolution *SE); + + /// dump - For debugging purposes. Dumps the constraint + /// out to OS. + void dump(raw_ostream &OS) const; + }; + + + /// establishNestingLevels - Examines the loop nesting of the Src and Dst + /// instructions and establishes their shared loops. Sets the variables + /// CommonLevels, SrcLevels, and MaxLevels. + /// The source and destination instructions needn't be contained in the same + /// loop. The routine establishNestingLevels finds the level of most deeply + /// nested loop that contains them both, CommonLevels. An instruction that's + /// not contained in a loop is at level = 0. MaxLevels is equal to the level + /// of the source plus the level of the destination, minus CommonLevels. + /// This lets us allocate vectors MaxLevels in length, with room for every + /// distinct loop referenced in both the source and destination subscripts. + /// The variable SrcLevels is the nesting depth of the source instruction. + /// It's used to help calculate distinct loops referenced by the destination. + /// Here's the map from loops to levels: + /// 0 - unused + /// 1 - outermost common loop + /// ... - other common loops + /// CommonLevels - innermost common loop + /// ... - loops containing Src but not Dst + /// SrcLevels - innermost loop containing Src but not Dst + /// ... - loops containing Dst but not Src + /// MaxLevels - innermost loop containing Dst but not Src + /// Consider the follow code fragment: + /// for (a = ...) { + /// for (b = ...) { + /// for (c = ...) { + /// for (d = ...) { + /// A[] = ...; + /// } + /// } + /// for (e = ...) { + /// for (f = ...) { + /// for (g = ...) { + /// ... = A[]; + /// } + /// } + /// } + /// } + /// } + /// If we're looking at the possibility of a dependence between the store + /// to A (the Src) and the load from A (the Dst), we'll note that they + /// have 2 loops in common, so CommonLevels will equal 2 and the direction + /// vector for Result will have 2 entries. SrcLevels = 4 and MaxLevels = 7. + /// A map from loop names to level indices would look like + /// a - 1 + /// b - 2 = CommonLevels + /// c - 3 + /// d - 4 = SrcLevels + /// e - 5 + /// f - 6 + /// g - 7 = MaxLevels + void establishNestingLevels(const Instruction *Src, + const Instruction *Dst); + + unsigned CommonLevels, SrcLevels, MaxLevels; + + /// mapSrcLoop - Given one of the loops containing the source, return + /// its level index in our numbering scheme. + unsigned mapSrcLoop(const Loop *SrcLoop) const; + + /// mapDstLoop - Given one of the loops containing the destination, + /// return its level index in our numbering scheme. + unsigned mapDstLoop(const Loop *DstLoop) const; + + /// isLoopInvariant - Returns true if Expression is loop invariant + /// in LoopNest. + bool isLoopInvariant(const SCEV *Expression, const Loop *LoopNest) const; + + /// removeMatchingExtensions - Examines a subscript pair. + /// If the source and destination are identically sign (or zero) + /// extended, it strips off the extension in an effort to + /// simplify the actual analysis. + void removeMatchingExtensions(Subscript *Pair); + + /// collectCommonLoops - Finds the set of loops from the LoopNest that + /// have a level <= CommonLevels and are referred to by the SCEV Expression. + void collectCommonLoops(const SCEV *Expression, + const Loop *LoopNest, + SmallBitVector &Loops) const; + + /// checkSrcSubscript - Examines the SCEV Src, returning true iff it's + /// linear. Collect the set of loops mentioned by Src. + bool checkSrcSubscript(const SCEV *Src, + const Loop *LoopNest, + SmallBitVector &Loops); + + /// checkDstSubscript - Examines the SCEV Dst, returning true iff it's + /// linear. Collect the set of loops mentioned by Dst. + bool checkDstSubscript(const SCEV *Dst, + const Loop *LoopNest, + SmallBitVector &Loops); + + /// isKnownPredicate - Compare X and Y using the predicate Pred. + /// Basically a wrapper for SCEV::isKnownPredicate, + /// but tries harder, especially in the presence of sign and zero + /// extensions and symbolics. + bool isKnownPredicate(ICmpInst::Predicate Pred, + const SCEV *X, + const SCEV *Y) const; + + /// collectUpperBound - All subscripts are the same type (on my machine, + /// an i64). The loop bound may be a smaller type. collectUpperBound + /// find the bound, if available, and zero extends it to the Type T. + /// (I zero extend since the bound should always be >= 0.) + /// If no upper bound is available, return NULL. + const SCEV *collectUpperBound(const Loop *l, Type *T) const; + + /// collectConstantUpperBound - Calls collectUpperBound(), then + /// attempts to cast it to SCEVConstant. If the cast fails, + /// returns NULL. + const SCEVConstant *collectConstantUpperBound(const Loop *l, Type *T) const; + + /// classifyPair - Examines the subscript pair (the Src and Dst SCEVs) + /// and classifies it as either ZIV, SIV, RDIV, MIV, or Nonlinear. + /// Collects the associated loops in a set. + Subscript::ClassificationKind classifyPair(const SCEV *Src, + const Loop *SrcLoopNest, + const SCEV *Dst, + const Loop *DstLoopNest, + SmallBitVector &Loops); + + /// testZIV - Tests the ZIV subscript pair (Src and Dst) for dependence. + /// Returns true if any possible dependence is disproved. + /// If there might be a dependence, returns false. + /// If the dependence isn't proven to exist, + /// marks the Result as inconsistent. + bool testZIV(const SCEV *Src, + const SCEV *Dst, + FullDependence &Result) const; + + /// testSIV - Tests the SIV subscript pair (Src and Dst) for dependence. + /// Things of the form [c1 + a1*i] and [c2 + a2*j], where + /// i and j are induction variables, c1 and c2 are loop invariant, + /// and a1 and a2 are constant. + /// Returns true if any possible dependence is disproved. + /// If there might be a dependence, returns false. + /// Sets appropriate direction vector entry and, when possible, + /// the distance vector entry. + /// If the dependence isn't proven to exist, + /// marks the Result as inconsistent. + bool testSIV(const SCEV *Src, + const SCEV *Dst, + unsigned &Level, + FullDependence &Result, + Constraint &NewConstraint, + const SCEV *&SplitIter) const; + + /// testRDIV - Tests the RDIV subscript pair (Src and Dst) for dependence. + /// Things of the form [c1 + a1*i] and [c2 + a2*j] + /// where i and j are induction variables, c1 and c2 are loop invariant, + /// and a1 and a2 are constant. + /// With minor algebra, this test can also be used for things like + /// [c1 + a1*i + a2*j][c2]. + /// Returns true if any possible dependence is disproved. + /// If there might be a dependence, returns false. + /// Marks the Result as inconsistent. + bool testRDIV(const SCEV *Src, + const SCEV *Dst, + FullDependence &Result) const; + + /// testMIV - Tests the MIV subscript pair (Src and Dst) for dependence. + /// Returns true if dependence disproved. + /// Can sometimes refine direction vectors. + bool testMIV(const SCEV *Src, + const SCEV *Dst, + const SmallBitVector &Loops, + FullDependence &Result) const; + + /// strongSIVtest - Tests the strong SIV subscript pair (Src and Dst) + /// for dependence. + /// Things of the form [c1 + a*i] and [c2 + a*i], + /// where i is an induction variable, c1 and c2 are loop invariant, + /// and a is a constant + /// Returns true if any possible dependence is disproved. + /// If there might be a dependence, returns false. + /// Sets appropriate direction and distance. + bool strongSIVtest(const SCEV *Coeff, + const SCEV *SrcConst, + const SCEV *DstConst, + const Loop *CurrentLoop, + unsigned Level, + FullDependence &Result, + Constraint &NewConstraint) const; + + /// weakCrossingSIVtest - Tests the weak-crossing SIV subscript pair + /// (Src and Dst) for dependence. + /// Things of the form [c1 + a*i] and [c2 - a*i], + /// where i is an induction variable, c1 and c2 are loop invariant, + /// and a is a constant. + /// Returns true if any possible dependence is disproved. + /// If there might be a dependence, returns false. + /// Sets appropriate direction entry. + /// Set consistent to false. + /// Marks the dependence as splitable. + bool weakCrossingSIVtest(const SCEV *SrcCoeff, + const SCEV *SrcConst, + const SCEV *DstConst, + const Loop *CurrentLoop, + unsigned Level, + FullDependence &Result, + Constraint &NewConstraint, + const SCEV *&SplitIter) const; + + /// ExactSIVtest - Tests the SIV subscript pair + /// (Src and Dst) for dependence. + /// Things of the form [c1 + a1*i] and [c2 + a2*i], + /// where i is an induction variable, c1 and c2 are loop invariant, + /// and a1 and a2 are constant. + /// Returns true if any possible dependence is disproved. + /// If there might be a dependence, returns false. + /// Sets appropriate direction entry. + /// Set consistent to false. + bool exactSIVtest(const SCEV *SrcCoeff, + const SCEV *DstCoeff, + const SCEV *SrcConst, + const SCEV *DstConst, + const Loop *CurrentLoop, + unsigned Level, + FullDependence &Result, + Constraint &NewConstraint) const; + + /// weakZeroSrcSIVtest - Tests the weak-zero SIV subscript pair + /// (Src and Dst) for dependence. + /// Things of the form [c1] and [c2 + a*i], + /// where i is an induction variable, c1 and c2 are loop invariant, + /// and a is a constant. See also weakZeroDstSIVtest. + /// Returns true if any possible dependence is disproved. + /// If there might be a dependence, returns false. + /// Sets appropriate direction entry. + /// Set consistent to false. + /// If loop peeling will break the dependence, mark appropriately. + bool weakZeroSrcSIVtest(const SCEV *DstCoeff, + const SCEV *SrcConst, + const SCEV *DstConst, + const Loop *CurrentLoop, + unsigned Level, + FullDependence &Result, + Constraint &NewConstraint) const; + + /// weakZeroDstSIVtest - Tests the weak-zero SIV subscript pair + /// (Src and Dst) for dependence. + /// Things of the form [c1 + a*i] and [c2], + /// where i is an induction variable, c1 and c2 are loop invariant, + /// and a is a constant. See also weakZeroSrcSIVtest. + /// Returns true if any possible dependence is disproved. + /// If there might be a dependence, returns false. + /// Sets appropriate direction entry. + /// Set consistent to false. + /// If loop peeling will break the dependence, mark appropriately. + bool weakZeroDstSIVtest(const SCEV *SrcCoeff, + const SCEV *SrcConst, + const SCEV *DstConst, + const Loop *CurrentLoop, + unsigned Level, + FullDependence &Result, + Constraint &NewConstraint) const; + + /// exactRDIVtest - Tests the RDIV subscript pair for dependence. + /// Things of the form [c1 + a*i] and [c2 + b*j], + /// where i and j are induction variable, c1 and c2 are loop invariant, + /// and a and b are constants. + /// Returns true if any possible dependence is disproved. + /// Marks the result as inconsistent. + /// Works in some cases that symbolicRDIVtest doesn't, + /// and vice versa. + bool exactRDIVtest(const SCEV *SrcCoeff, + const SCEV *DstCoeff, + const SCEV *SrcConst, + const SCEV *DstConst, + const Loop *SrcLoop, + const Loop *DstLoop, + FullDependence &Result) const; + + /// symbolicRDIVtest - Tests the RDIV subscript pair for dependence. + /// Things of the form [c1 + a*i] and [c2 + b*j], + /// where i and j are induction variable, c1 and c2 are loop invariant, + /// and a and b are constants. + /// Returns true if any possible dependence is disproved. + /// Marks the result as inconsistent. + /// Works in some cases that exactRDIVtest doesn't, + /// and vice versa. Can also be used as a backup for + /// ordinary SIV tests. + bool symbolicRDIVtest(const SCEV *SrcCoeff, + const SCEV *DstCoeff, + const SCEV *SrcConst, + const SCEV *DstConst, + const Loop *SrcLoop, + const Loop *DstLoop) const; + + /// gcdMIVtest - Tests an MIV subscript pair for dependence. + /// Returns true if any possible dependence is disproved. + /// Marks the result as inconsistent. + /// Can sometimes disprove the equal direction for 1 or more loops. + // Can handle some symbolics that even the SIV tests don't get, + /// so we use it as a backup for everything. + bool gcdMIVtest(const SCEV *Src, + const SCEV *Dst, + FullDependence &Result) const; + + /// banerjeeMIVtest - Tests an MIV subscript pair for dependence. + /// Returns true if any possible dependence is disproved. + /// Marks the result as inconsistent. + /// Computes directions. + bool banerjeeMIVtest(const SCEV *Src, + const SCEV *Dst, + const SmallBitVector &Loops, + FullDependence &Result) const; + + /// collectCoefficientInfo - Walks through the subscript, + /// collecting each coefficient, the associated loop bounds, + /// and recording its positive and negative parts for later use. + CoefficientInfo *collectCoeffInfo(const SCEV *Subscript, + bool SrcFlag, + const SCEV *&Constant) const; + + /// getPositivePart - X^+ = max(X, 0). + /// + const SCEV *getPositivePart(const SCEV *X) const; + + /// getNegativePart - X^- = min(X, 0). + /// + const SCEV *getNegativePart(const SCEV *X) const; + + /// getLowerBound - Looks through all the bounds info and + /// computes the lower bound given the current direction settings + /// at each level. + const SCEV *getLowerBound(BoundInfo *Bound) const; + + /// getUpperBound - Looks through all the bounds info and + /// computes the upper bound given the current direction settings + /// at each level. + const SCEV *getUpperBound(BoundInfo *Bound) const; + + /// exploreDirections - Hierarchically expands the direction vector + /// search space, combining the directions of discovered dependences + /// in the DirSet field of Bound. Returns the number of distinct + /// dependences discovered. If the dependence is disproved, + /// it will return 0. + unsigned exploreDirections(unsigned Level, + CoefficientInfo *A, + CoefficientInfo *B, + BoundInfo *Bound, + const SmallBitVector &Loops, + unsigned &DepthExpanded, + const SCEV *Delta) const; + + /// testBounds - Returns true iff the current bounds are plausible. + /// + bool testBounds(unsigned char DirKind, + unsigned Level, + BoundInfo *Bound, + const SCEV *Delta) const; + + /// findBoundsALL - Computes the upper and lower bounds for level K + /// using the * direction. Records them in Bound. + void findBoundsALL(CoefficientInfo *A, + CoefficientInfo *B, + BoundInfo *Bound, + unsigned K) const; + + /// findBoundsLT - Computes the upper and lower bounds for level K + /// using the < direction. Records them in Bound. + void findBoundsLT(CoefficientInfo *A, + CoefficientInfo *B, + BoundInfo *Bound, + unsigned K) const; + + /// findBoundsGT - Computes the upper and lower bounds for level K + /// using the > direction. Records them in Bound. + void findBoundsGT(CoefficientInfo *A, + CoefficientInfo *B, + BoundInfo *Bound, + unsigned K) const; + + /// findBoundsEQ - Computes the upper and lower bounds for level K + /// using the = direction. Records them in Bound. + void findBoundsEQ(CoefficientInfo *A, + CoefficientInfo *B, + BoundInfo *Bound, + unsigned K) const; + + /// intersectConstraints - Updates X with the intersection + /// of the Constraints X and Y. Returns true if X has changed. + bool intersectConstraints(Constraint *X, + const Constraint *Y); + + /// propagate - Review the constraints, looking for opportunities + /// to simplify a subscript pair (Src and Dst). + /// Return true if some simplification occurs. + /// If the simplification isn't exact (that is, if it is conservative + /// in terms of dependence), set consistent to false. + bool propagate(const SCEV *&Src, + const SCEV *&Dst, + SmallBitVector &Loops, + SmallVector<Constraint, 4> &Constraints, + bool &Consistent); + + /// propagateDistance - Attempt to propagate a distance + /// constraint into a subscript pair (Src and Dst). + /// Return true if some simplification occurs. + /// If the simplification isn't exact (that is, if it is conservative + /// in terms of dependence), set consistent to false. + bool propagateDistance(const SCEV *&Src, + const SCEV *&Dst, + Constraint &CurConstraint, + bool &Consistent); + + /// propagatePoint - Attempt to propagate a point + /// constraint into a subscript pair (Src and Dst). + /// Return true if some simplification occurs. + bool propagatePoint(const SCEV *&Src, + const SCEV *&Dst, + Constraint &CurConstraint); + + /// propagateLine - Attempt to propagate a line + /// constraint into a subscript pair (Src and Dst). + /// Return true if some simplification occurs. + /// If the simplification isn't exact (that is, if it is conservative + /// in terms of dependence), set consistent to false. + bool propagateLine(const SCEV *&Src, + const SCEV *&Dst, + Constraint &CurConstraint, + bool &Consistent); + + /// findCoefficient - Given a linear SCEV, + /// return the coefficient corresponding to specified loop. + /// If there isn't one, return the SCEV constant 0. + /// For example, given a*i + b*j + c*k, returning the coefficient + /// corresponding to the j loop would yield b. + const SCEV *findCoefficient(const SCEV *Expr, + const Loop *TargetLoop) const; + + /// zeroCoefficient - Given a linear SCEV, + /// return the SCEV given by zeroing out the coefficient + /// corresponding to the specified loop. + /// For example, given a*i + b*j + c*k, zeroing the coefficient + /// corresponding to the j loop would yield a*i + c*k. + const SCEV *zeroCoefficient(const SCEV *Expr, + const Loop *TargetLoop) const; + + /// addToCoefficient - Given a linear SCEV Expr, + /// return the SCEV given by adding some Value to the + /// coefficient corresponding to the specified TargetLoop. + /// For example, given a*i + b*j + c*k, adding 1 to the coefficient + /// corresponding to the j loop would yield a*i + (b+1)*j + c*k. + const SCEV *addToCoefficient(const SCEV *Expr, + const Loop *TargetLoop, + const SCEV *Value) const; + + /// updateDirection - Update direction vector entry + /// based on the current constraint. + void updateDirection(Dependence::DVEntry &Level, + const Constraint &CurConstraint) const; + public: + static char ID; // Class identification, replacement for typeinfo + DependenceAnalysis() : FunctionPass(ID) { + initializeDependenceAnalysisPass(*PassRegistry::getPassRegistry()); + } + + bool runOnFunction(Function &F); + void releaseMemory(); + void getAnalysisUsage(AnalysisUsage &) const; + void print(raw_ostream &, const Module * = 0) const; + }; // class DependenceAnalysis + + /// createDependenceAnalysisPass - This creates an instance of the + /// DependenceAnalysis pass. + FunctionPass *createDependenceAnalysisPass(); + +} // namespace llvm + +#endif |