1 //===--- VarBypassDetector.cpp - Bypass jumps detector ------------*- C++ -*-=//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains VarBypassDetector class, which is used to detect
11 // local variable declarations which can be bypassed by jumps.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CLANG_LIB_CODEGEN_VARBYPASSDETECTOR_H
16 #define LLVM_CLANG_LIB_CODEGEN_VARBYPASSDETECTOR_H
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/DenseSet.h"
20 #include "llvm/ADT/SmallVector.h"
30 /// The class detects jumps which bypass local variables declaration:
35 /// This is simplified version of JumpScopeChecker. Primary differences:
36 /// * Detects only jumps into the scope local variables.
37 /// * Does not detect jumps out of the scope of local variables.
38 /// * Not limited to variables with initializers, JumpScopeChecker is limited.
39 class VarBypassDetector {
40 // Scope information. Contains a parent scope and related variable
42 llvm::SmallVector<std::pair<unsigned, const VarDecl *>, 48> Scopes;
43 // List of jumps with scopes.
44 llvm::SmallVector<std::pair<const Stmt *, unsigned>, 16> FromScopes;
45 // Lookup map to find scope for destinations.
46 llvm::DenseMap<const Stmt *, unsigned> ToScopes;
47 // Set of variables which were bypassed by some jump.
48 llvm::DenseSet<const VarDecl *> Bypasses;
49 // If true assume that all variables are being bypassed.
50 bool AlwaysBypassed = false;
53 void Init(const Stmt *Body);
55 /// Returns true if the variable declaration was by bypassed by any goto or
57 bool IsBypassed(const VarDecl *D) const {
58 return AlwaysBypassed || Bypasses.find(D) != Bypasses.end();
62 bool BuildScopeInformation(const Decl *D, unsigned &ParentScope);
63 bool BuildScopeInformation(const Stmt *S, unsigned &origParentScope);
65 void Detect(unsigned From, unsigned To);