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//===--- VarBypassDetector.cpp - Bypass jumps detector ------------*- C++ -*-=//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See 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.
#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;
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.find(D) != Bypasses.end();
bool BuildScopeInformation(const Decl *D, unsigned &ParentScope);
bool BuildScopeInformation(const Stmt *S, unsigned &origParentScope);
void Detect();
void Detect(unsigned From, unsigned To);