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