unittests/IR/CFGBuilder.h

   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