#ifndef LLVM_ANALYSIS_LOOP_DEPENDENCE_ANALYSIS_H
#define LLVM_ANALYSIS_LOOP_DEPENDENCE_ANALYSIS_H
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/FoldingSet.h"
+#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/LoopPass.h"
-#include "llvm/Support/raw_ostream.h"
-#include <iosfwd>
+#include "llvm/Support/Allocator.h"
namespace llvm {
class AliasAnalysis;
class AnalysisUsage;
class ScalarEvolution;
+class SCEV;
class Value;
+class raw_ostream;
class LoopDependenceAnalysis : public LoopPass {
- Loop *L;
AliasAnalysis *AA;
ScalarEvolution *SE;
+ /// L - The loop we are currently analysing.
+ Loop *L;
+
+ /// TODO: doc
+ enum DependenceResult { Independent = 0, Dependent = 1, Unknown = 2 };
+
+ /// TODO: doc
+ struct Subscript {
+ /// TODO: Add distance, direction, breaking conditions, ...
+ };
+
+ /// DependencePair - Represents a data dependence relation between to memory
+ /// reference instructions.
+ struct DependencePair : public FastFoldingSetNode {
+ Value *A;
+ Value *B;
+ DependenceResult Result;
+ SmallVector<Subscript, 4> Subscripts;
+
+ DependencePair(const FoldingSetNodeID &ID, Value *a, Value *b) :
+ FastFoldingSetNode(ID), A(a), B(b), Result(Unknown), Subscripts() {}
+ };
+
+ /// findOrInsertDependencePair - Return true if a DependencePair for the
+ /// given Values already exists, false if a new DependencePair had to be
+ /// created. The third argument is set to the pair found or created.
+ bool findOrInsertDependencePair(Value*, Value*, DependencePair*&);
+
+ /// getLoops - Collect all loops of the loop nest L in which
+ /// a given SCEV is variant.
+ void getLoops(const SCEV*, DenseSet<const Loop*>*) const;
+
+ /// isLoopInvariant - True if a given SCEV is invariant in all loops of the
+ /// loop nest starting at the innermost loop L.
+ bool isLoopInvariant(const SCEV*) const;
+
+ /// isAffine - An SCEV is affine with respect to the loop nest starting at
+ /// the innermost loop L if it is of the form A+B*X where A, B are invariant
+ /// in the loop nest and X is a induction variable in the loop nest.
+ bool isAffine(const SCEV*) const;
+
+ /// TODO: doc
+ bool isZIVPair(const SCEV*, const SCEV*) const;
+ bool isSIVPair(const SCEV*, const SCEV*) const;
+ DependenceResult analyseZIV(const SCEV*, const SCEV*, Subscript*) const;
+ DependenceResult analyseSIV(const SCEV*, const SCEV*, Subscript*) const;
+ DependenceResult analyseMIV(const SCEV*, const SCEV*, Subscript*) const;
+ DependenceResult analyseSubscript(const SCEV*, const SCEV*, Subscript*) const;
+ DependenceResult analysePair(DependencePair*) const;
+
public:
static char ID; // Class identification, replacement for typeinfo
- LoopDependenceAnalysis() : LoopPass(&ID) {}
+ LoopDependenceAnalysis() : LoopPass(ID) {
+ initializeLoopDependenceAnalysisPass(*PassRegistry::getPassRegistry());
+ }
- /// TODO: docs
+ /// isDependencePair - Check whether two values can possibly give rise to
+ /// a data dependence: that is the case if both are instructions accessing
+ /// memory and at least one of those accesses is a write.
bool isDependencePair(const Value*, const Value*) const;
+
+ /// depends - Return a boolean indicating if there is a data dependence
+ /// between two instructions.
bool depends(Value*, Value*);
bool runOnLoop(Loop*, LPPassManager&);
-
+ virtual void releaseMemory();
virtual void getAnalysisUsage(AnalysisUsage&) const;
-
void print(raw_ostream&, const Module* = 0) const;
- virtual void print(std::ostream&, const Module* = 0) const;
-}; // class LoopDependenceAnalysis
+private:
+ FoldingSet<DependencePair> Pairs;
+ BumpPtrAllocator PairAllocator;
+}; // class LoopDependenceAnalysis
// createLoopDependenceAnalysisPass - This creates an instance of the
// LoopDependenceAnalysis pass.