1 //===- llvm/Analysis/MemoryDependenceAnalysis.h - Memory Deps --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the MemoryDependenceAnalysis analysis pass.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_ANALYSIS_MEMORY_DEPENDENCE_H
15 #define LLVM_ANALYSIS_MEMORY_DEPENDENCE_H
17 #include "llvm/Pass.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/SmallPtrSet.h"
27 /// MemoryDependenceAnalysis - This is an analysis that determines, for a
28 /// given memory operation, what preceding memory operations it depends on.
29 /// It builds on alias analysis information, and tries to provide a lazy,
30 /// caching interface to a common kind of alias information query.
31 class MemoryDependenceAnalysis : public FunctionPass {
33 // A map from instructions to their dependency, with a boolean
34 // flags for whether this mapping is confirmed or not
35 typedef DenseMap<Instruction*, std::pair<Instruction*, bool> > depMapType;
36 depMapType depGraphLocal;
38 // A map from instructions to their non-local dependencies.
39 typedef DenseMap<Instruction*, DenseMap<BasicBlock*, Value*> >
41 nonLocalDepMapType depGraphNonLocal;
43 // A reverse mapping form dependencies to the dependees. This is
44 // used when removing instructions to keep the cache coherent.
45 typedef DenseMap<Value*, SmallPtrSet<Instruction*, 4> > reverseDepMapType;
46 reverseDepMapType reverseDep;
48 // A reverse mapping form dependencies to the non-local dependees.
49 reverseDepMapType reverseDepNonLocal;
52 // Special marker indicating that the query has no dependency
53 // in the specified block.
54 static Instruction* const NonLocal;
56 // Special marker indicating that the query has no dependency at all
57 static Instruction* const None;
59 // Special marker indicating a dirty cache entry
60 static Instruction* const Dirty;
62 static char ID; // Class identification, replacement for typeinfo
63 MemoryDependenceAnalysis() : FunctionPass(&ID) {}
65 /// Pass Implementation stuff. This doesn't do any analysis.
67 bool runOnFunction(Function &) {return false; }
69 /// Clean up memory in between runs
70 void releaseMemory() {
71 depGraphLocal.clear();
72 depGraphNonLocal.clear();
74 reverseDepNonLocal.clear();
77 /// getAnalysisUsage - Does not modify anything. It uses Value Numbering
78 /// and Alias Analysis.
80 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
82 /// getDependency - Return the instruction on which a memory operation
83 /// depends, starting with start.
84 Instruction* getDependency(Instruction* query, Instruction* start = 0,
85 BasicBlock* block = 0);
87 /// getNonLocalDependency - Fills the passed-in map with the non-local
88 /// dependencies of the queries. The map will contain NonLocal for
89 /// blocks between the query and its dependencies.
90 void getNonLocalDependency(Instruction* query,
91 DenseMap<BasicBlock*, Value*>& resp);
93 /// removeInstruction - Remove an instruction from the dependence analysis,
94 /// updating the dependence of instructions that previously depended on it.
95 void removeInstruction(Instruction* rem);
97 /// dropInstruction - Remove an instruction from the analysis, making
98 /// absolutely conservative assumptions when updating the cache. This is
99 /// useful, for example when an instruction is changed rather than removed.
100 void dropInstruction(Instruction* drop);
103 /// verifyRemoved - Verify that the specified instruction does not occur
104 /// in our internal data structures.
105 void verifyRemoved(Instruction *Inst) const;
107 Instruction* getCallSiteDependency(CallSite C, Instruction* start,
109 void nonLocalHelper(Instruction* query, BasicBlock* block,
110 DenseMap<BasicBlock*, Value*>& resp);
113 } // End llvm namespace