1 //===- LiveVariables.h - Live Variable Analysis for Source CFGs -*- 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 implements Live Variables analysis for source-level CFGs.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CLANG_LIVEVARIABLES_H
15 #define LLVM_CLANG_LIVEVARIABLES_H
17 #include "clang/AST/Decl.h"
18 #include "clang/Analysis/AnalysisContext.h"
19 #include "llvm/ADT/DenseMap.h"
20 #include "llvm/ADT/ImmutableSet.h"
30 class LiveVariables : public ManagedAnalysis {
32 class LivenessValues {
35 llvm::ImmutableSet<const Stmt *> liveStmts;
36 llvm::ImmutableSet<const VarDecl *> liveDecls;
38 bool equals(const LivenessValues &V) const;
41 : liveStmts(0), liveDecls(0) {}
43 LivenessValues(llvm::ImmutableSet<const Stmt *> LiveStmts,
44 llvm::ImmutableSet<const VarDecl *> LiveDecls)
45 : liveStmts(LiveStmts), liveDecls(LiveDecls) {}
49 bool isLive(const Stmt *S) const;
50 bool isLive(const VarDecl *D) const;
52 friend class LiveVariables;
56 virtual void anchor();
58 virtual ~Observer() {}
60 /// A callback invoked right before invoking the
61 /// liveness transfer function on the given statement.
62 virtual void observeStmt(const Stmt *S,
63 const CFGBlock *currentBlock,
64 const LivenessValues& V) {}
66 /// Called when the live variables analysis registers
67 /// that a variable is killed.
68 virtual void observerKill(const DeclRefExpr *DR) {}
72 virtual ~LiveVariables();
74 /// Compute the liveness information for a given CFG.
75 static LiveVariables *computeLiveness(AnalysisDeclContext &analysisContext,
78 /// Return true if a variable is live at the end of a
80 bool isLive(const CFGBlock *B, const VarDecl *D);
82 /// Returns true if a variable is live at the beginning of the
83 /// the statement. This query only works if liveness information
84 /// has been recorded at the statement level (see runOnAllBlocks), and
85 /// only returns liveness information for block-level expressions.
86 bool isLive(const Stmt *S, const VarDecl *D);
88 /// Returns true the block-level expression "value" is live
89 /// before the given block-level expression (see runOnAllBlocks).
90 bool isLive(const Stmt *Loc, const Stmt *StmtVal);
92 /// Print to stderr the liveness information associated with
94 void dumpBlockLiveness(const SourceManager& M);
96 void runOnAllBlocks(Observer &obs);
98 static LiveVariables *create(AnalysisDeclContext &analysisContext) {
99 return computeLiveness(analysisContext, true);
102 static const void *getTag();
105 LiveVariables(void *impl);
109 class RelaxedLiveVariables : public LiveVariables {
111 static LiveVariables *create(AnalysisDeclContext &analysisContext) {
112 return computeLiveness(analysisContext, false);
115 static const void *getTag();
118 } // end namespace clang