| //===--- VarBypassDetector.cpp - 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.find(D) != Bypasses.end(); |
| } |
| |
| private: |
| bool BuildScopeInformation(const Decl *D, unsigned &ParentScope); |
| bool BuildScopeInformation(const Stmt *S, unsigned &origParentScope); |
| void Detect(); |
| void Detect(unsigned From, unsigned To); |
| }; |
| } |
| } |
| |
| #endif |