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1//===--- VarBypassDetector.h - Bypass jumps detector --------------*- C++ -*-=//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// This file contains VarBypassDetector class, which is used to detect10// local variable declarations which can be bypassed by jumps.11//12//===----------------------------------------------------------------------===//13 14#ifndef LLVM_CLANG_LIB_CODEGEN_VARBYPASSDETECTOR_H15#define LLVM_CLANG_LIB_CODEGEN_VARBYPASSDETECTOR_H16 17#include "CodeGenModule.h"18#include "clang/AST/Decl.h"19#include "llvm/ADT/DenseMap.h"20#include "llvm/ADT/DenseSet.h"21#include "llvm/ADT/SmallVector.h"22 23namespace clang {24 25class Decl;26class Stmt;27class VarDecl;28 29namespace CodeGen {30 31/// The class detects jumps which bypass local variables declaration:32/// goto L;33/// int a;34/// L:35///36/// This is simplified version of JumpScopeChecker. Primary differences:37/// * Detects only jumps into the scope local variables.38/// * Does not detect jumps out of the scope of local variables.39/// * Not limited to variables with initializers, JumpScopeChecker is limited.40class VarBypassDetector {41 // Scope information. Contains a parent scope and related variable42 // declaration.43 llvm::SmallVector<std::pair<unsigned, const VarDecl *>, 48> Scopes;44 // List of jumps with scopes.45 llvm::SmallVector<std::pair<const Stmt *, unsigned>, 16> FromScopes;46 // Lookup map to find scope for destinations.47 llvm::DenseMap<const Stmt *, unsigned> ToScopes;48 // Set of variables which were bypassed by some jump.49 llvm::DenseSet<const VarDecl *> Bypasses;50 // If true assume that all variables are being bypassed.51 bool AlwaysBypassed = false;52 53public:54 void Init(CodeGenModule &CGM, const Stmt *Body);55 56 /// Returns true if the variable declaration was by bypassed by any goto or57 /// switch statement.58 bool IsBypassed(const VarDecl *D) const {59 return AlwaysBypassed || Bypasses.contains(D);60 }61 62private:63 bool BuildScopeInformation(CodeGenModule &CGM, const Decl *D,64 unsigned &ParentScope);65 bool BuildScopeInformation(CodeGenModule &CGM, const Stmt *S,66 unsigned &origParentScope);67 void Detect();68 void Detect(unsigned From, unsigned To);69};70}71}72 73#endif74