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//===- LiveVariables.h - Live Variable Analysis for Source CFGs -*- C++ --*-//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file implements Live Variables analysis for source-level CFGs.
#include "clang/AST/Decl.h"
#include "clang/Analysis/AnalysisContext.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/ImmutableSet.h"
namespace clang {
class CFG;
class CFGBlock;
class Stmt;
class DeclRefExpr;
class SourceManager;
class LiveVariables : public ManagedAnalysis {
class LivenessValues {
llvm::ImmutableSet<const Stmt *> liveStmts;
llvm::ImmutableSet<const VarDecl *> liveDecls;
bool equals(const LivenessValues &V) const;
: liveStmts(nullptr), liveDecls(nullptr) {}
LivenessValues(llvm::ImmutableSet<const Stmt *> LiveStmts,
llvm::ImmutableSet<const VarDecl *> LiveDecls)
: liveStmts(LiveStmts), liveDecls(LiveDecls) {}
~LivenessValues() {}
bool isLive(const Stmt *S) const;
bool isLive(const VarDecl *D) const;
friend class LiveVariables;
class Observer {
virtual void anchor();
virtual ~Observer() {}
/// A callback invoked right before invoking the
/// liveness transfer function on the given statement.
virtual void observeStmt(const Stmt *S,
const CFGBlock *currentBlock,
const LivenessValues& V) {}
/// Called when the live variables analysis registers
/// that a variable is killed.
virtual void observerKill(const DeclRefExpr *DR) {}
virtual ~LiveVariables();
/// Compute the liveness information for a given CFG.
static LiveVariables *computeLiveness(AnalysisDeclContext &analysisContext,
bool killAtAssign);
/// Return true if a variable is live at the end of a
/// specified block.
bool isLive(const CFGBlock *B, const VarDecl *D);
/// Returns true if a variable is live at the beginning of the
/// the statement. This query only works if liveness information
/// has been recorded at the statement level (see runOnAllBlocks), and
/// only returns liveness information for block-level expressions.
bool isLive(const Stmt *S, const VarDecl *D);
/// Returns true the block-level expression "value" is live
/// before the given block-level expression (see runOnAllBlocks).
bool isLive(const Stmt *Loc, const Stmt *StmtVal);
/// Print to stderr the liveness information associated with
/// each basic block.
void dumpBlockLiveness(const SourceManager& M);
void runOnAllBlocks(Observer &obs);
static LiveVariables *create(AnalysisDeclContext &analysisContext) {
return computeLiveness(analysisContext, true);
static const void *getTag();
LiveVariables(void *impl);
void *impl;
class RelaxedLiveVariables : public LiveVariables {
static LiveVariables *create(AnalysisDeclContext &analysisContext) {
return computeLiveness(analysisContext, false);
static const void *getTag();
} // end namespace clang