1 //===- CFGBuilder.h - CFG building and updating utility ----------*- 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 /// \file
9 /// CFGBuilders provides utilities fo building and updating CFG for testing
10 /// purposes.
11 ///
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_UNITTESTS_CFG_BUILDER_H
15 #define LLVM_UNITTESTS_CFG_BUILDER_H
16 
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/Optional.h"
19 #include "llvm/ADT/StringMap.h"
20 #include "llvm/ADT/StringRef.h"
21 #include "llvm/Support/Debug.h"
22 
23 #include <memory>
24 #include <set>
25 #include <tuple>
26 #include <vector>
27 
28 namespace llvm {
29 
30 class LLVMContext;
31 class Module;
32 class Function;
33 class BasicBlock;
34 class raw_ostream;
35 
36 struct CFGHolder {
37   std::unique_ptr<LLVMContext> Context;
38   std::unique_ptr<Module> M;
39   Function *F;
40 
41   CFGHolder(StringRef ModuleName = "m", StringRef FunctionName = "foo");
42   ~CFGHolder(); // Defined in the .cpp file so we can use forward declarations.
43 };
44 
45 /// \brief
46 /// CFGBuilder builds IR with specific CFG, based on the supplied list of arcs.
47 /// It's able to apply the provided updates and automatically modify the IR.
48 ///
49 /// Internally it makes every basic block end with either SwitchInst or with
50 /// UnreachableInst. When all arc to a BB are deleted, the BB remains in the
51 /// function and doesn't get deleted.
52 ///
53 class CFGBuilder {
54 public:
55   struct Arc {
56     StringRef From;
57     StringRef To;
58 
59     friend bool operator<(const Arc &LHS, const Arc &RHS) {
60       return std::tie(LHS.From, LHS.To) <
61              std::tie(RHS.From, RHS.To);
62     }
63   };
64 
65   enum class ActionKind { Insert, Delete };
66   struct Update {
67     ActionKind Action;
68     Arc Edge;
69   };
70 
71   CFGBuilder(Function *F, const std::vector<Arc> &InitialArcs,
72              std::vector<Update> Updates);
73 
74   BasicBlock *getOrAddBlock(StringRef BlockName);
75   Optional<Update> getNextUpdate() const;
76   Optional<Update> applyUpdate();
77   void dump(raw_ostream &OS = dbgs()) const;
78 
79 private:
80   void buildCFG(const std::vector<Arc> &Arcs);
81   bool connect(const Arc &A);
82   bool disconnect(const Arc &A);
83 
84   Function *F;
85   unsigned UpdateIdx = 0;
86   StringMap<BasicBlock *> NameToBlock;
87   std::set<Arc> Arcs;
88   std::vector<Update> Updates;
89 };
90 
91 } // namespace llvm
92 
93 #endif
94