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-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file contains VarBypassDetector class, which is used to detect
10// local variable declarations which can be bypassed by jumps.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_LIB_CODEGEN_VARBYPASSDETECTOR_H
15#define LLVM_CLANG_LIB_CODEGEN_VARBYPASSDETECTOR_H
16
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 variable
42 // 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 or
57 /// switch statement.
58 bool IsBypassed(const VarDecl *D) const {
59 return AlwaysBypassed || Bypasses.contains(V: 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#endif
74