[llvm] [DA][NFC] clang-format DependenceAnalysis (PR #151505)
Ryotaro Kasuga via llvm-commits
llvm-commits at lists.llvm.org
Wed Aug 6 06:12:09 PDT 2025
================
@@ -47,994 +47,910 @@
#include "llvm/Support/Compiler.h"
namespace llvm {
- class AAResults;
- template <typename T> class ArrayRef;
- class Loop;
- class LoopInfo;
- 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.
- ///
- /// When a dependence graph is built, each Dependence will be a member of
- /// the set of predecessor edges for its destination instruction and a set
- /// if successor edges for its source instruction. These sets are represented
- /// as singly-linked lists, with the "next" fields stored in the dependence
- /// itelf.
- class LLVM_ABI Dependence {
- protected:
- Dependence(Dependence &&) = default;
- Dependence &operator=(Dependence &&) = default;
-
- public:
- Dependence(Instruction *Source, Instruction *Destination,
- const SCEVUnionPredicate &A)
- : Src(Source), Dst(Destination), Assumptions(A) {}
- virtual ~Dependence() = default;
-
- /// 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 : unsigned char {
- 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 = nullptr; // NULL implies no distance available.
- DVEntry()
- : Direction(ALL), Scalar(true), PeelFirst(false), PeelLast(false),
- Splitable(false) {}
+class AAResults;
+template <typename T> class ArrayRef;
+class Loop;
+class LoopInfo;
+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.
+///
+/// When a dependence graph is built, each Dependence will be a member of
+/// the set of predecessor edges for its destination instruction and a set
+/// if successor edges for its source instruction. These sets are represented
+/// as singly-linked lists, with the "next" fields stored in the dependence
+/// itelf.
+class LLVM_ABI Dependence {
+protected:
+ Dependence(Dependence &&) = default;
+ Dependence &operator=(Dependence &&) = default;
+
+public:
+ Dependence(Instruction *Source, Instruction *Destination,
+ const SCEVUnionPredicate &A)
+ : Src(Source), Dst(Destination), Assumptions(A) {}
+ virtual ~Dependence() = default;
+
+ /// 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 : unsigned char {
+ 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 = nullptr; // NULL implies no distance available.
+ DVEntry()
+ : Direction(ALL), Scalar(true), PeelFirst(false), PeelLast(false),
+ Splitable(false) {}
+ };
- /// getSrc - Returns the source instruction for this dependence.
- ///
- Instruction *getSrc() const { return Src; }
-
- /// getDst - Returns the destination instruction for this dependence.
- ///
- Instruction *getDst() const { return Dst; }
-
- /// isInput - Returns true if this is an input dependence.
- ///
- bool isInput() const;
+ /// getSrc - Returns the source instruction for this dependence.
+ Instruction *getSrc() const { return Src; }
- /// isOutput - Returns true if this is an output dependence.
- ///
- bool isOutput() const;
+ /// getDst - Returns the destination instruction for this dependence.
+ Instruction *getDst() const { return Dst; }
- /// isFlow - Returns true if this is a flow (aka true) dependence.
- ///
- bool isFlow() const;
+ /// isInput - Returns true if this is an input dependence.
+ bool isInput() const;
- /// isAnti - Returns true if this is an anti dependence.
- ///
- bool isAnti() const;
+ /// isOutput - Returns true if this is an output dependence.
+ bool isOutput() const;
- /// isOrdered - Returns true if dependence is Output, Flow, or Anti
- ///
- bool isOrdered() const { return isOutput() || isFlow() || isAnti(); }
+ /// isFlow - Returns true if this is a flow (aka true) dependence.
+ bool isFlow() const;
- /// isUnordered - Returns true if dependence is Input
- ///
- bool isUnordered() const { return isInput(); }
+ /// isAnti - Returns true if this is an anti dependence.
+ bool isAnti() const;
- /// isLoopIndependent - Returns true if this is a loop-independent
- /// dependence.
- virtual bool isLoopIndependent() const { return true; }
+ /// isOrdered - Returns true if dependence is Output, Flow, or Anti
+ bool isOrdered() const { return isOutput() || isFlow() || isAnti(); }
- /// isConfused - Returns true if this dependence is confused
- /// (the compiler understands nothing and makes worst-case
- /// assumptions).
- virtual bool isConfused() const { return true; }
+ /// isUnordered - Returns true if dependence is Input
+ bool isUnordered() const { return isInput(); }
- /// isConsistent - Returns true if this dependence is consistent
- /// (occurs every time the source and destination are executed).
- virtual bool isConsistent() const { return false; }
+ /// isLoopIndependent - Returns true if this is a loop-independent
+ /// dependence.
+ virtual bool isLoopIndependent() const { return true; }
- /// getLevels - Returns the number of common loops surrounding the
- /// source and destination of the dependence.
- virtual unsigned getLevels() const { return 0; }
+ /// isConfused - Returns true if this dependence is confused
+ /// (the compiler understands nothing and makes worst-case assumptions).
+ virtual bool isConfused() const { return true; }
- /// getDirection - Returns the direction associated with a particular
- /// level.
- virtual unsigned getDirection(unsigned Level) const { return DVEntry::ALL; }
+ /// isConsistent - Returns true if this dependence is consistent
+ /// (occurs every time the source and destination are executed).
+ virtual bool isConsistent() const { return false; }
- /// getDistance - Returns the distance (or NULL) associated with a
- /// particular level.
- virtual const SCEV *getDistance(unsigned Level) const { return nullptr; }
+ /// getLevels - Returns the number of common loops surrounding the
+ /// source and destination of the dependence.
+ virtual unsigned getLevels() const { return 0; }
- /// Check if the direction vector is negative. A negative direction
- /// vector means Src and Dst are reversed in the actual program.
- virtual bool isDirectionNegative() const { return false; }
+ /// getDirection - Returns the direction associated with a particular level.
+ virtual unsigned getDirection(unsigned Level) const { return DVEntry::ALL; }
- /// If the direction vector is negative, normalize the direction
- /// vector to make it non-negative. Normalization is done by reversing
- /// Src and Dst, plus reversing the dependence directions and distances
- /// in the vector.
- virtual bool normalize(ScalarEvolution *SE) { return false; }
+ /// getDistance - Returns the distance (or NULL) associated with a particular
+ /// level.
+ virtual const SCEV *getDistance(unsigned Level) const { return nullptr; }
- /// isPeelFirst - Returns true if peeling the first iteration from
- /// this loop will break this dependence.
- virtual bool isPeelFirst(unsigned Level) const { return false; }
+ /// Check if the direction vector is negative. A negative direction
+ /// vector means Src and Dst are reversed in the actual program.
+ virtual bool isDirectionNegative() const { return false; }
+
+ /// If the direction vector is negative, normalize the direction
+ /// vector to make it non-negative. Normalization is done by reversing
+ /// Src and Dst, plus reversing the dependence directions and distances
+ /// in the vector.
+ virtual bool normalize(ScalarEvolution *SE) { 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; }
+ /// isPeelFirst - Returns true if peeling the first iteration from
+ /// this loop will break this dependence.
+ virtual bool isPeelFirst(unsigned Level) const { return false; }
- /// isSplitable - Returns true if splitting this loop will break
- /// the dependence.
- virtual bool isSplitable(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; }
- /// 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;
+ /// isSplitable - Returns true if splitting this loop will break the
+ /// dependence.
+ virtual bool isSplitable(unsigned Level) const { return false; }
- /// getNextPredecessor - Returns the value of the NextPredecessor
- /// field.
- const Dependence *getNextPredecessor() const { return NextPredecessor; }
+ /// 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;
+
+ /// getNextPredecessor - Returns the value of the NextPredecessor field.
+ const Dependence *getNextPredecessor() const { return NextPredecessor; }
+
+ /// getNextSuccessor - Returns the value of the NextSuccessor field.
+ const Dependence *getNextSuccessor() const { return NextSuccessor; }
+
+ /// setNextPredecessor - Sets the value of the NextPredecessor
+ /// field.
+ void setNextPredecessor(const Dependence *pred) { NextPredecessor = pred; }
+
+ /// setNextSuccessor - Sets the value of the NextSuccessor field.
+ void setNextSuccessor(const Dependence *succ) { NextSuccessor = succ; }
+
+ /// getRuntimeAssumptions - Returns the runtime assumptions under which this
+ /// Dependence relation is valid.
+ SCEVUnionPredicate getRuntimeAssumptions() const { return Assumptions; }
+
+ /// dump - For debugging purposes, dumps a dependence to OS.
+ void dump(raw_ostream &OS) const;
+
+protected:
+ Instruction *Src, *Dst;
+
+private:
+ SCEVUnionPredicate Assumptions;
+ const Dependence *NextPredecessor = nullptr, *NextSuccessor = nullptr;
+ friend class DependenceInfo;
+};
+
+/// 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 LLVM_ABI FullDependence final : public Dependence {
+public:
+ FullDependence(Instruction *Source, Instruction *Destination,
+ const SCEVUnionPredicate &Assumes,
+ bool PossiblyLoopIndependent, unsigned Levels);
+
+ /// isLoopIndependent - Returns true if this is a loop-independent
+ /// dependence.
+ bool isLoopIndependent() const override { return LoopIndependent; }
+
+ /// isConfused - Returns true if this dependence is confused
+ /// (the compiler understands nothing and makes worst-case
+ /// assumptions).
+ bool isConfused() const override { return false; }
+
+ /// isConsistent - Returns true if this dependence is consistent
+ /// (occurs every time the source and destination are executed).
+ bool isConsistent() const override { return Consistent; }
+
+ /// getLevels - Returns the number of common loops surrounding the
+ /// source and destination of the dependence.
+ unsigned getLevels() const override { return Levels; }
+
+ /// getDirection - Returns the direction associated with a particular
+ /// level.
+ unsigned getDirection(unsigned Level) const override;
+
+ /// getDistance - Returns the distance (or NULL) associated with a
+ /// particular level.
+ const SCEV *getDistance(unsigned Level) const override;
+
+ /// Check if the direction vector is negative. A negative direction
+ /// vector means Src and Dst are reversed in the actual program.
+ bool isDirectionNegative() const override;
+
+ /// If the direction vector is negative, normalize the direction
+ /// vector to make it non-negative. Normalization is done by reversing
+ /// Src and Dst, plus reversing the dependence directions and distances
+ /// in the vector.
+ bool normalize(ScalarEvolution *SE) override;
+
+ /// isPeelFirst - Returns true if peeling the first iteration from
+ /// this loop will break this dependence.
+ bool isPeelFirst(unsigned Level) const override;
+
+ /// isPeelLast - Returns true if peeling the last iteration from
+ /// this loop will break this dependence.
+ bool isPeelLast(unsigned Level) const override;
+
+ /// isSplitable - Returns true if splitting the loop will break
+ /// the dependence.
+ bool isSplitable(unsigned Level) const override;
+
+ /// 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 override;
+
+private:
+ unsigned short Levels;
+ bool LoopIndependent;
+ bool Consistent; // Init to true, then refine.
+ std::unique_ptr<DVEntry[]> DV;
+ friend class DependenceInfo;
+};
+
+/// DependenceInfo - This class is the main dependence-analysis driver.
+class DependenceInfo {
+public:
+ DependenceInfo(Function *F, AAResults *AA, ScalarEvolution *SE, LoopInfo *LI)
+ : AA(AA), SE(SE), LI(LI), F(F) {}
+
+ /// Handle transitive invalidation when the cached analysis results go away.
+ LLVM_ABI bool invalidate(Function &F, const PreservedAnalyses &PA,
+ FunctionAnalysisManager::Invalidator &Inv);
+
+ /// 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. By default,
+ /// the dependence test collects a set of runtime assumptions that cannot be
+ /// solved at compilation time. By default UnderRuntimeAssumptions is false
+ /// for a safe approximation of the dependence relation that does not
+ /// require runtime checks.
+ LLVM_ABI std::unique_ptr<Dependence>
+ depends(Instruction *Src, Instruction *Dst,
+ bool UnderRuntimeAssumptions = false);
+
+ /// getSplitIteration - Give a dependence that's splittable 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.
+ LLVM_ABI const SCEV *getSplitIteration(const Dependence &Dep, unsigned Level);
+
+ Function *getFunction() const { return F; }
+
+ /// getRuntimeAssumptions - Returns all the runtime assumptions under which
+ /// the dependence test is valid.
+ LLVM_ABI SCEVUnionPredicate getRuntimeAssumptions() const;
+
+private:
+ AAResults *AA;
+ ScalarEvolution *SE;
+ LoopInfo *LI;
+ Function *F;
+ SmallVector<const SCEVPredicate *, 4> Assumptions;
+
+ /// 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;
+ };
- /// getNextSuccessor - Returns the value of the NextSuccessor
- /// field.
- const Dependence *getNextSuccessor() const { return NextSuccessor; }
+ struct CoefficientInfo {
+ const SCEV *Coeff;
+ const SCEV *PosPart;
+ const SCEV *NegPart;
+ const SCEV *Iterations;
+ };
- /// setNextPredecessor - Sets the value of the NextPredecessor
- /// field.
- void setNextPredecessor(const Dependence *pred) { NextPredecessor = pred; }
+ struct BoundInfo {
+ const SCEV *Iterations;
+ const SCEV *Upper[8];
+ const SCEV *Lower[8];
+ unsigned char Direction;
+ unsigned char DirSet;
+ };
- /// setNextSuccessor - Sets the value of the NextSuccessor
- /// field.
- void setNextSuccessor(const Dependence *succ) { NextSuccessor = succ; }
+ /// 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;
- /// getRuntimeAssumptions - Returns the runtime assumptions under which this
- /// Dependence relation is valid.
- SCEVUnionPredicate getRuntimeAssumptions() const { return Assumptions; }
+ public:
+ /// isEmpty - Return true if the constraint is of kind Empty.
+ bool isEmpty() const { return Kind == Empty; }
- /// dump - For debugging purposes, dumps a dependence to OS.
- ///
- void dump(raw_ostream &OS) const;
+ /// isPoint - Return true if the constraint is of kind Point.
+ bool isPoint() const { return Kind == Point; }
- protected:
- Instruction *Src, *Dst;
+ /// isDistance - Return true if the constraint is of kind Distance.
+ bool isDistance() const { return Kind == Distance; }
- private:
- SCEVUnionPredicate Assumptions;
- const Dependence *NextPredecessor = nullptr, *NextSuccessor = nullptr;
- friend class DependenceInfo;
- };
+ /// 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; }
- /// 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 LLVM_ABI FullDependence final : public Dependence {
- public:
- FullDependence(Instruction *Source, Instruction *Destination,
- const SCEVUnionPredicate &Assumes,
- bool PossiblyLoopIndependent, unsigned Levels);
-
- /// isLoopIndependent - Returns true if this is a loop-independent
- /// dependence.
- bool isLoopIndependent() const override { return LoopIndependent; }
-
- /// isConfused - Returns true if this dependence is confused
- /// (the compiler understands nothing and makes worst-case
- /// assumptions).
- bool isConfused() const override { return false; }
-
- /// isConsistent - Returns true if this dependence is consistent
- /// (occurs every time the source and destination are executed).
- bool isConsistent() const override { return Consistent; }
-
- /// getLevels - Returns the number of common loops surrounding the
- /// source and destination of the dependence.
- unsigned getLevels() const override { return Levels; }
-
- /// getDirection - Returns the direction associated with a particular
- /// level.
- unsigned getDirection(unsigned Level) const override;
-
- /// getDistance - Returns the distance (or NULL) associated with a
- /// particular level.
- const SCEV *getDistance(unsigned Level) const override;
-
- /// Check if the direction vector is negative. A negative direction
- /// vector means Src and Dst are reversed in the actual program.
- bool isDirectionNegative() const override;
-
- /// If the direction vector is negative, normalize the direction
- /// vector to make it non-negative. Normalization is done by reversing
- /// Src and Dst, plus reversing the dependence directions and distances
- /// in the vector.
- bool normalize(ScalarEvolution *SE) override;
-
- /// isPeelFirst - Returns true if peeling the first iteration from
- /// this loop will break this dependence.
- bool isPeelFirst(unsigned Level) const override;
-
- /// isPeelLast - Returns true if peeling the last iteration from
- /// this loop will break this dependence.
- bool isPeelLast(unsigned Level) const override;
-
- /// isSplitable - Returns true if splitting the loop will break
- /// the dependence.
- bool isSplitable(unsigned Level) const override;
-
- /// 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 override;
+ /// isAny - Return true if the constraint is of kind Any;
+ bool isAny() const { return Kind == Any; }
- private:
- unsigned short Levels;
- bool LoopIndependent;
- bool Consistent; // Init to true, then refine.
- std::unique_ptr<DVEntry[]> DV;
- friend class DependenceInfo;
- };
+ /// getX - If constraint is a point <X, Y>, returns X.
+ /// Otherwise assert.
+ LLVM_ABI const SCEV *getX() const;
- /// DependenceInfo - This class is the main dependence-analysis driver.
- ///
- class DependenceInfo {
- public:
- DependenceInfo(Function *F, AAResults *AA, ScalarEvolution *SE,
- LoopInfo *LI)
- : AA(AA), SE(SE), LI(LI), F(F) {}
-
- /// Handle transitive invalidation when the cached analysis results go away.
- LLVM_ABI bool invalidate(Function &F, const PreservedAnalyses &PA,
- FunctionAnalysisManager::Invalidator &Inv);
-
- /// 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. By default,
- /// the dependence test collects a set of runtime assumptions that cannot be
- /// solved at compilation time. By default UnderRuntimeAssumptions is false
- /// for a safe approximation of the dependence relation that does not
- /// require runtime checks.
- LLVM_ABI std::unique_ptr<Dependence>
- depends(Instruction *Src, Instruction *Dst,
- bool UnderRuntimeAssumptions = false);
-
- /// getSplitIteration - Give a dependence that's splittable 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.
- LLVM_ABI const SCEV *getSplitIteration(const Dependence &Dep,
- unsigned Level);
-
- Function *getFunction() const { return F; }
-
- /// getRuntimeAssumptions - Returns all the runtime assumptions under which
- /// the dependence test is valid.
- LLVM_ABI SCEVUnionPredicate getRuntimeAssumptions() const;
+ /// getY - If constraint is a point <X, Y>, returns Y.
+ /// Otherwise assert.
+ LLVM_ABI const SCEV *getY() const;
- private:
- AAResults *AA;
- ScalarEvolution *SE;
- LoopInfo *LI;
- Function *F;
- SmallVector<const SCEVPredicate *, 4> Assumptions;
-
- /// 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;
- };
+ /// getA - If constraint is a line AX + BY = C, returns A.
+ /// Otherwise assert.
+ LLVM_ABI const SCEV *getA() const;
- struct CoefficientInfo {
- const SCEV *Coeff;
- const SCEV *PosPart;
- const SCEV *NegPart;
- const SCEV *Iterations;
- };
+ /// getB - If constraint is a line AX + BY = C, returns B.
+ /// Otherwise assert.
+ LLVM_ABI const SCEV *getB() const;
- struct BoundInfo {
- const SCEV *Iterations;
- const SCEV *Upper[8];
- const SCEV *Lower[8];
- unsigned char Direction;
- unsigned char DirSet;
- };
+ /// getC - If constraint is a line AX + BY = C, returns C.
+ /// Otherwise assert.
+ LLVM_ABI const SCEV *getC() const;
- /// 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.
- LLVM_ABI const SCEV *getX() const;
-
- /// getY - If constraint is a point <X, Y>, returns Y.
- /// Otherwise assert.
- LLVM_ABI const SCEV *getY() const;
-
- /// getA - If constraint is a line AX + BY = C, returns A.
- /// Otherwise assert.
- LLVM_ABI const SCEV *getA() const;
-
- /// getB - If constraint is a line AX + BY = C, returns B.
- /// Otherwise assert.
- LLVM_ABI const SCEV *getB() const;
-
- /// getC - If constraint is a line AX + BY = C, returns C.
- /// Otherwise assert.
- LLVM_ABI const SCEV *getC() const;
-
- /// getD - If constraint is a distance, returns D.
- /// Otherwise assert.
- LLVM_ABI const SCEV *getD() const;
-
- /// getAssociatedLoop - Returns the loop associated with this constraint.
- LLVM_ABI const Loop *getAssociatedLoop() const;
-
- /// setPoint - Change a constraint to Point.
- LLVM_ABI void setPoint(const SCEV *X, const SCEV *Y,
- const Loop *CurrentLoop);
-
- /// setLine - Change a constraint to Line.
- LLVM_ABI void setLine(const SCEV *A, const SCEV *B, const SCEV *C,
- const Loop *CurrentLoop);
-
- /// setDistance - Change a constraint to Distance.
- LLVM_ABI void setDistance(const SCEV *D, const Loop *CurrentLoop);
-
- /// setEmpty - Change a constraint to Empty.
- LLVM_ABI void setEmpty();
-
- /// setAny - Change a constraint to Any.
- LLVM_ABI void setAny(ScalarEvolution *SE);
-
- /// dump - For debugging purposes. Dumps the constraint
- /// out to OS.
- LLVM_ABI void dump(raw_ostream &OS) const;
- };
+ /// getD - If constraint is a distance, returns D.
+ /// Otherwise assert.
+ LLVM_ABI const SCEV *getD() 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;
-
- /// Makes sure all subscript pairs share the same integer type by
- /// sign-extending as necessary.
- /// Sign-extending a subscript is safe because getelementptr assumes the
- /// array subscripts are signed.
- void unifySubscriptType(ArrayRef<Subscript *> Pairs);
-
- /// 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;
-
- /// isKnownLessThan - Compare to see if S is less than Size
- /// Another wrapper for isKnownNegative(S - max(Size, 1)) with some extra
- /// checking if S is an AddRec and we can prove lessthan using the loop
- /// bounds.
- bool isKnownLessThan(const SCEV *S, const SCEV *Size) const;
-
- /// isKnownNonNegative - Compare to see if S is known not to be negative
- /// Uses the fact that S comes from Ptr, which may be an inbound GEP,
- /// Proving there is no wrapping going on.
- bool isKnownNonNegative(const SCEV *S, const Value *Ptr) 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;
+ /// getAssociatedLoop - Returns the loop associated with this constraint.
+ LLVM_ABI const Loop *getAssociatedLoop() 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;
+ /// setPoint - Change a constraint to Point.
+ LLVM_ABI void setPoint(const SCEV *X, const SCEV *Y,
+ const Loop *CurrentLoop);
- /// 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,
- SmallVectorImpl<Constraint> &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;
-
- /// Given a linear access function, tries to recover subscripts
- /// for each dimension of the array element access.
- bool tryDelinearize(Instruction *Src, Instruction *Dst,
- SmallVectorImpl<Subscript> &Pair);
-
- /// Tries to delinearize \p Src and \p Dst access functions for a fixed size
- /// multi-dimensional array. Calls tryDelinearizeFixedSizeImpl() to
- /// delinearize \p Src and \p Dst separately,
- bool tryDelinearizeFixedSize(Instruction *Src, Instruction *Dst,
- const SCEV *SrcAccessFn,
- const SCEV *DstAccessFn,
- SmallVectorImpl<const SCEV *> &SrcSubscripts,
- SmallVectorImpl<const SCEV *> &DstSubscripts);
-
- /// Tries to delinearize access function for a multi-dimensional array with
- /// symbolic runtime sizes.
- /// Returns true upon success and false otherwise.
- bool tryDelinearizeParametricSize(
- Instruction *Src, Instruction *Dst, const SCEV *SrcAccessFn,
- const SCEV *DstAccessFn, SmallVectorImpl<const SCEV *> &SrcSubscripts,
- SmallVectorImpl<const SCEV *> &DstSubscripts);
-
- /// checkSubscript - Helper function for checkSrcSubscript and
- /// checkDstSubscript to avoid duplicate code
- bool checkSubscript(const SCEV *Expr, const Loop *LoopNest,
- SmallBitVector &Loops, bool IsSrc);
- }; // class DependenceInfo
-
- /// AnalysisPass to compute dependence information in a function
- class DependenceAnalysis : public AnalysisInfoMixin<DependenceAnalysis> {
- public:
- typedef DependenceInfo Result;
- LLVM_ABI Result run(Function &F, FunctionAnalysisManager &FAM);
+ /// setLine - Change a constraint to Line.
+ LLVM_ABI void setLine(const SCEV *A, const SCEV *B, const SCEV *C,
+ const Loop *CurrentLoop);
- private:
- LLVM_ABI static AnalysisKey Key;
- friend struct AnalysisInfoMixin<DependenceAnalysis>;
- }; // class DependenceAnalysis
+ /// setDistance - Change a constraint to Distance.
+ LLVM_ABI void setDistance(const SCEV *D, const Loop *CurrentLoop);
- /// Printer pass to dump DA results.
- struct DependenceAnalysisPrinterPass
- : public PassInfoMixin<DependenceAnalysisPrinterPass> {
- DependenceAnalysisPrinterPass(raw_ostream &OS,
- bool NormalizeResults = false)
- : OS(OS), NormalizeResults(NormalizeResults) {}
+ /// setEmpty - Change a constraint to Empty.
+ LLVM_ABI void setEmpty();
- LLVM_ABI PreservedAnalyses run(Function &F, FunctionAnalysisManager &FAM);
+ /// setAny - Change a constraint to Any.
+ LLVM_ABI void setAny(ScalarEvolution *SE);
- static bool isRequired() { return true; }
+ /// dump - For debugging purposes. Dumps the constraint
+ /// out to OS.
+ LLVM_ABI void dump(raw_ostream &OS) const;
+ };
- private:
- raw_ostream &OS;
- bool NormalizeResults;
- }; // class DependenceAnalysisPrinterPass
+ /// 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;
+
+ /// Makes sure all subscript pairs share the same integer type by
+ /// sign-extending as necessary.
+ /// Sign-extending a subscript is safe because getelementptr assumes the
+ /// array subscripts are signed.
+ void unifySubscriptType(ArrayRef<Subscript *> Pairs);
+
+ /// 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;
+
+ /// isKnownLessThan - Compare to see if S is less than Size
+ /// Another wrapper for isKnownNegative(S - max(Size, 1)) with some extra
+ /// checking if S is an AddRec and we can prove lessthan using the loop
+ /// bounds.
+ bool isKnownLessThan(const SCEV *S, const SCEV *Size) const;
+
+ /// isKnownNonNegative - Compare to see if S is known not to be negative
+ /// Uses the fact that S comes from Ptr, which may be an inbound GEP,
+ /// Proving there is no wrapping going on.
+ bool isKnownNonNegative(const SCEV *S, const Value *Ptr) 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;
- /// Legacy pass manager pass to access dependence information
- class LLVM_ABI DependenceAnalysisWrapperPass : public FunctionPass {
- public:
- static char ID; // Class identification, replacement for typeinfo
- DependenceAnalysisWrapperPass();
+ /// 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;
- bool runOnFunction(Function &F) override;
- void releaseMemory() override;
- void getAnalysisUsage(AnalysisUsage &) const override;
- void print(raw_ostream &, const Module * = nullptr) const override;
- DependenceInfo &getDI() 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;
- private:
- std::unique_ptr<DependenceInfo> info;
- }; // class DependenceAnalysisWrapperPass
+ /// getPositivePart - X^+ = max(X, 0).
+ ///
----------------
kasuga-fj wrote:
Can we remove this line as well?
https://github.com/llvm/llvm-project/pull/151505
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