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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