//===--- VarBypassDetector.h - Bypass jumps detector --------------*- 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 contains VarBypassDetector class, which is used to detect

// local variable declarations which can be bypassed by jumps.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_LIB_CODEGEN_VARBYPASSDETECTOR_H

#define LLVM_CLANG_LIB_CODEGEN_VARBYPASSDETECTOR_H

#include "clang/AST/Decl.h"

#include "llvm/ADT/DenseMap.h"

#include "llvm/ADT/DenseSet.h"

#include "llvm/ADT/SmallVector.h"

namespace clang {

class Decl;

class Stmt;

class VarDecl;

namespace CodeGen {

/// The class detects jumps which bypass local variables declaration:

///    goto L;

///    int a;

///  L:

///

/// This is simplified version of JumpScopeChecker. Primary differences:

///  * Detects only jumps into the scope local variables.

///  * Does not detect jumps out of the scope of local variables.

///  * Not limited to variables with initializers, JumpScopeChecker is limited.

class VarBypassDetector {

  // Scope information. Contains a parent scope and related variable

  // declaration.

  llvm::SmallVector<std::pair<unsigned, const VarDecl *>, 48> Scopes;

  // List of jumps with scopes.

  llvm::SmallVector<std::pair<const Stmt *, unsigned>, 16> FromScopes;

  // Lookup map to find scope for destinations.

  llvm::DenseMap<const Stmt *, unsigned> ToScopes;

  // Set of variables which were bypassed by some jump.

  llvm::DenseSet<const VarDecl *> Bypasses;

  // If true assume that all variables are being bypassed.

  bool AlwaysBypassed = false;

public:

  void Init(const Stmt *Body);

  /// Returns true if the variable declaration was by bypassed by any goto or

  /// switch statement.

  bool IsBypassed(const VarDecl *D) const {

    return AlwaysBypassed || 
Bypasses.contains(D)254k
;

  }

private:

  bool BuildScopeInformation(const Decl *D, unsigned &ParentScope);

  bool BuildScopeInformation(const Stmt *S, unsigned &origParentScope);

  void Detect();

  void Detect(unsigned From, unsigned To);

};

}

}

#endif