// of memory references in a function, returning either NULL, for no dependence,
// or a more-or-less detailed description of the dependence between them.
//
+// This pass exists to support the DependenceGraph pass. There are two separate
+// passes because there's a useful separation of concerns. A dependence exists
+// if two conditions are met:
+//
+// 1) Two instructions reference the same memory location, and
+// 2) There is a flow of control leading from one instruction to the other.
+//
+// DependenceAnalysis attacks the first condition; DependenceGraph will attack
+// the second (it's not yet ready).
+//
// Please note that this is work in progress and the interface is subject to
// change.
//
#ifndef LLVM_ANALYSIS_DEPENDENCEANALYSIS_H
#define LLVM_ANALYSIS_DEPENDENCEANALYSIS_H
-#include "llvm/BasicBlock.h"
-#include "llvm/Function.h"
-#include "llvm/Instruction.h"
-#include "llvm/Pass.h"
#include "llvm/ADT/SmallBitVector.h"
-#include "llvm/Analysis/ScalarEvolution.h"
-#include "llvm/Analysis/ScalarEvolutionExpressions.h"
-#include "llvm/Analysis/AliasAnalysis.h"
-#include "llvm/Analysis/LoopInfo.h"
-#include "llvm/Support/raw_ostream.h"
-
+#include "llvm/IR/Instructions.h"
+#include "llvm/Pass.h"
namespace llvm {
class AliasAnalysis;
+ class Loop;
+ class LoopInfo;
class ScalarEvolution;
class SCEV;
- class Value;
+ class SCEVConstant;
class raw_ostream;
/// Dependence - This class represents a dependence between two memory
/// 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 preceed the destination; in contrast,
+ /// 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 Dependence {
public:
- Dependence(const Instruction *Source,
- const Instruction *Destination) :
- Src(Source), Dst(Destination) {}
+ Dependence(Instruction *Source,
+ Instruction *Destination) :
+ Src(Source),
+ Dst(Destination),
+ NextPredecessor(NULL),
+ NextSuccessor(NULL) {}
virtual ~Dependence() {}
/// Dependence::DVEntry - Each level in the distance/direction vector
/// getSrc - Returns the source instruction for this dependence.
///
- const Instruction *getSrc() const { return Src; }
+ Instruction *getSrc() const { return Src; }
/// getDst - Returns the destination instruction for this dependence.
///
- const Instruction *getDst() const { return Dst; }
+ Instruction *getDst() const { return Dst; }
/// isInput - Returns true if this is an input dependence.
///
virtual bool isConsistent() const { return false; }
/// getLevels - Returns the number of common loops surrounding the
- /// souce and destination of the dependence.
+ /// source and destination of the dependence.
virtual unsigned getLevels() const { return 0; }
/// getDirection - Returns the direction associated with a particular
/// 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;
+ }
+
/// dump - For debugging purposes, dumps a dependence to OS.
///
void dump(raw_ostream &OS) const;
private:
- const Instruction *Src, *Dst;
+ Instruction *Src, *Dst;
+ const Dependence *NextPredecessor, *NextSuccessor;
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
+ /// 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 preceed the destination; in contrast,
+ /// 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,
+ FullDependence(Instruction *Src,
+ Instruction *Dst,
bool LoopIndependent,
unsigned Levels);
~FullDependence() {
- delete DV;
+ delete[] DV;
}
/// isLoopIndependent - Returns true if this is a loop-independent
bool isConsistent() const { return Consistent; }
/// getLevels - Returns the number of common loops surrounding the
- /// souce and destination of the dependence.
+ /// source and destination of the dependence.
unsigned getLevels() const { return Levels; }
/// getDirection - Returns the direction associated with a particular
/// 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
+ void operator=(const DependenceAnalysis &) LLVM_DELETED_FUNCTION;
+ DependenceAnalysis(const DependenceAnalysis &) LLVM_DELETED_FUNCTION;
public:
/// depends - Tests for a dependence between the Src and Dst instructions.
/// Returns NULL if no dependence; otherwise, returns a Dependence (or a
/// 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,
+ Dependence *depends(Instruction *Src,
+ Instruction *Dst,
bool PossiblyLoopIndependent);
- /// getSplitIteration - Give a dependence that's splitable at some
+ /// getSplitIteration - Give a dependence that's splittable at some
/// particular level, return the iteration that should be used to split
/// the loop.
///
/// isKnownPredicate - Compare X and Y using the predicate Pred.
/// Basically a wrapper for SCEV::isKnownPredicate,
- /// but tries harder, especially in the presense of sign and zero
+ /// but tries harder, especially in the presence of sign and zero
/// extensions and symbolics.
bool isKnownPredicate(ICmpInst::Predicate Pred,
const SCEV *X,
/// 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 inconsistant.
+ /// Marks the result as inconsistent.
/// Works in some cases that symbolicRDIVtest doesn't,
/// and vice versa.
bool exactRDIVtest(const SCEV *SrcCoeff,
/// 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 inconsistant.
+ /// 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.
/// gcdMIVtest - Tests an MIV subscript pair for dependence.
/// Returns true if any possible dependence is disproved.
- /// Marks the result as inconsistant.
+ /// 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.
/// banerjeeMIVtest - Tests an MIV subscript pair for dependence.
/// Returns true if any possible dependence is disproved.
- /// Marks the result as inconsistant.
+ /// Marks the result as inconsistent.
/// Computes directions.
bool banerjeeMIVtest(const SCEV *Src,
const SCEV *Dst,
static char ID; // Class identification, replacement for typeinfo
DependenceAnalysis() : FunctionPass(ID) {
initializeDependenceAnalysisPass(*PassRegistry::getPassRegistry());
- };
+ }
bool runOnFunction(Function &F);
void releaseMemory();
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