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//===- LiveVariables.h - Live Variable Analysis for Source CFGs -*- C++ --*-//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements Live Variables analysis for source-level CFGs.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_ANALYSIS_ANALYSES_LIVEVARIABLES_H
#define LLVM_CLANG_ANALYSIS_ANALYSES_LIVEVARIABLES_H
#include "clang/AST/Decl.h"
#include "clang/Analysis/AnalysisDeclContext.h"
#include "llvm/ADT/ImmutableSet.h"
namespace clang {
class CFG;
class CFGBlock;
class Stmt;
class DeclRefExpr;
class SourceManager;
class LiveVariables : public ManagedAnalysis {
public:
class LivenessValues {
public:
llvm::ImmutableSet<const Stmt *> liveStmts;
llvm::ImmutableSet<const VarDecl *> liveDecls;
llvm::ImmutableSet<const BindingDecl *> liveBindings;
bool equals(const LivenessValues &V) const;
LivenessValues()
: liveStmts(nullptr), liveDecls(nullptr), liveBindings(nullptr) {}
LivenessValues(llvm::ImmutableSet<const Stmt *> LiveStmts,
llvm::ImmutableSet<const VarDecl *> LiveDecls,
llvm::ImmutableSet<const BindingDecl *> LiveBindings)
: liveStmts(LiveStmts), liveDecls(LiveDecls),
liveBindings(LiveBindings) {}
bool isLive(const Stmt *S) const;
bool isLive(const VarDecl *D) const;
friend class LiveVariables;
};
class Observer {
virtual void anchor();
public:
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) {}
};
~LiveVariables() override;
/// 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 variable liveness information associated with
/// each basic block.
void dumpBlockLiveness(const SourceManager &M);
/// Print to stderr the statement liveness information associated with
/// each basic block.
void dumpStmtLiveness(const SourceManager &M);
void runOnAllBlocks(Observer &obs);
static LiveVariables *create(AnalysisDeclContext &analysisContext) {
return computeLiveness(analysisContext, true);
}
static const void *getTag();
private:
LiveVariables(void *impl);
void *impl;
};
class RelaxedLiveVariables : public LiveVariables {
public:
static LiveVariables *create(AnalysisDeclContext &analysisContext) {
return computeLiveness(analysisContext, false);
}
static const void *getTag();
};
} // end namespace clang
#endif
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