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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.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_LIVEVARIABLES_H
#define LLVM_CLANG_LIVEVARIABLES_H
#include "clang/AST/Decl.h"
#include "clang/Analysis/Support/BlkExprDeclBitVector.h"
#include "clang/Analysis/FlowSensitive/DataflowValues.h"
namespace clang {
class Stmt;
class DeclRefExpr;
class SourceManager;
struct LiveVariables_ValueTypes {
struct ObserverTy;
// We keep dataflow state for declarations and block-level expressions;
typedef StmtDeclBitVector_Types::ValTy ValTy;
// We need to keep track of both declarations and CFGBlock-level expressions,
// (so that we don't explore such expressions twice). We also want
// to compute liveness information for block-level expressions, since these
// act as "temporary" values.
struct AnalysisDataTy : public StmtDeclBitVector_Types::AnalysisDataTy {
ObserverTy* Observer;
ValTy AlwaysLive;
AnalysisDataTy() : Observer(NULL) {}
};
//===-----------------------------------------------------===//
// ObserverTy - Observer for uninitialized values queries.
//===-----------------------------------------------------===//
struct ObserverTy {
virtual ~ObserverTy() {}
/// ObserveStmt - A callback invoked right before invoking the
/// liveness transfer function on the given statement.
virtual void ObserveStmt(Stmt* S, const AnalysisDataTy& AD,
const ValTy& V) {}
virtual void ObserverKill(DeclRefExpr* DR) {}
};
};
class LiveVariables : public DataflowValues<LiveVariables_ValueTypes,
dataflow::backward_analysis_tag> {
public:
typedef LiveVariables_ValueTypes::ObserverTy ObserverTy;
LiveVariables(ASTContext& Ctx, CFG& cfg);
/// IsLive - Return true if a variable is live at beginning of a
/// specified block.
bool isLive(const CFGBlock* B, const VarDecl* D) const;
/// IsLive - 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) const;
/// IsLive - 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) const;
/// IsLive - Return true if a variable is live according to the
/// provided livness bitvector.
bool isLive(const ValTy& V, const VarDecl* D) const;
/// dumpLiveness - Print to stderr the liveness information encoded
/// by a specified bitvector.
void dumpLiveness(const ValTy& V, SourceManager& M) const;
/// dumpBlockLiveness - Print to stderr the liveness information
/// associated with each basic block.
void dumpBlockLiveness(SourceManager& M) const;
/// getNumDecls - Return the number of variables (declarations) that
/// whose liveness status is being tracked by the dataflow
/// analysis.
unsigned getNumDecls() const { return getAnalysisData().getNumDecls(); }
/// IntializeValues - This routine can perform extra initialization, but
/// for LiveVariables this does nothing since all that logic is in
/// the constructor.
void InitializeValues(const CFG& cfg) {}
void runOnCFG(CFG& cfg);
/// runOnAllBlocks - Propagate the dataflow values once for each block,
/// starting from the current dataflow values. 'recordStmtValues' indicates
/// whether the method should store dataflow values per each individual
/// block-level expression.
void runOnAllBlocks(const CFG& cfg, ObserverTy* Obs,
bool recordStmtValues=false);
};
} // end namespace clang
#endif
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