1 //===- CFGReachabilityAnalysis.h - Basic reachability analysis --*- 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 defines a flow-sensitive, (mostly) path-insensitive reachability
10 // analysis based on Clang's CFGs.  Clients can query if a given basic block
11 // is reachable within the CFG.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_CLANG_ANALYSIS_ANALYSES_CFGREACHABILITYANALYSIS_H
16 #define LLVM_CLANG_ANALYSIS_ANALYSES_CFGREACHABILITYANALYSIS_H
17 
18 #include "llvm/ADT/BitVector.h"
19 #include "llvm/ADT/DenseMap.h"
20 
21 namespace clang {
22 
23 class CFG;
24 class CFGBlock;
25 
26 // A class that performs reachability queries for CFGBlocks. Several internal
27 // checks in this checker require reachability information. The requests all
28 // tend to have a common destination, so we lazily do a predecessor search
29 // from the destination node and cache the results to prevent work
30 // duplication.
31 class CFGReverseBlockReachabilityAnalysis {
32   using ReachableSet = llvm::BitVector;
33   using ReachableMap = llvm::DenseMap<unsigned, ReachableSet>;
34 
35   ReachableSet analyzed;
36   ReachableMap reachable;
37 
38 public:
39   CFGReverseBlockReachabilityAnalysis(const CFG &cfg);
40 
41   /// Returns true if the block 'Dst' can be reached from block 'Src'.
42   bool isReachable(const CFGBlock *Src, const CFGBlock *Dst);
43 
44 private:
45   void mapReachability(const CFGBlock *Dst);
46 };
47 
48 } // namespace clang
49 
50 #endif // LLVM_CLANG_ANALYSIS_ANALYSES_CFGREACHABILITYANALYSIS_H
51