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thirdparty/capstone/suite/synctools/tablegen/include/llvm/IR/CFG.h

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+//===- CFG.h ----------------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+/// \file
+///
+/// This file provides various utilities for inspecting and working with the
+/// control flow graph in LLVM IR. This includes generic facilities for
+/// iterating successors and predecessors of basic blocks, the successors of
+/// specific terminator instructions, etc. It also defines specializations of
+/// GraphTraits that allow Function and BasicBlock graphs to be treated as
+/// proper graphs for generic algorithms.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_IR_CFG_H
+#define LLVM_IR_CFG_H
+
+#include "llvm/ADT/GraphTraits.h"
+#include "llvm/ADT/iterator.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Value.h"
+#include "llvm/Support/Casting.h"
+#include <cassert>
+#include <cstddef>
+#include <iterator>
+
+namespace llvm {
+
+class Instruction;
+class Use;
+
+//===----------------------------------------------------------------------===//
+// BasicBlock pred_iterator definition
+//===----------------------------------------------------------------------===//
+
+template <class Ptr, class USE_iterator> // Predecessor Iterator
+class PredIterator {
+public:
+  using iterator_category = std::forward_iterator_tag;
+  using value_type = Ptr;
+  using difference_type = std::ptrdiff_t;
+  using pointer = Ptr *;
+  using reference = Ptr *;
+
+private:
+  using Self = PredIterator<Ptr, USE_iterator>;
+  USE_iterator It;
+
+  inline void advancePastNonTerminators() {
+    // Loop to ignore non-terminator uses (for example BlockAddresses).
+    while (!It.atEnd()) {
+      if (auto *Inst = dyn_cast<Instruction>(*It))
+        if (Inst->isTerminator())
+          break;
+
+      ++It;
+    }
+  }
+
+public:
+  PredIterator() = default;
+  explicit inline PredIterator(Ptr *bb) : It(bb->user_begin()) {
+    advancePastNonTerminators();
+  }
+  inline PredIterator(Ptr *bb, bool) : It(bb->user_end()) {}
+
+  inline bool operator==(const Self& x) const { return It == x.It; }
+  inline bool operator!=(const Self& x) const { return !operator==(x); }
+
+  inline reference operator*() const {
+    assert(!It.atEnd() && "pred_iterator out of range!");
+    return cast<Instruction>(*It)->getParent();
+  }
+  inline pointer *operator->() const { return &operator*(); }
+
+  inline Self& operator++() {   // Preincrement
+    assert(!It.atEnd() && "pred_iterator out of range!");
+    ++It; advancePastNonTerminators();
+    return *this;
+  }
+
+  inline Self operator++(int) { // Postincrement
+    Self tmp = *this; ++*this; return tmp;
+  }
+
+  /// getOperandNo - Return the operand number in the predecessor's
+  /// terminator of the successor.
+  unsigned getOperandNo() const {
+    return It.getOperandNo();
+  }
+
+  /// getUse - Return the operand Use in the predecessor's terminator
+  /// of the successor.
+  Use &getUse() const {
+    return It.getUse();
+  }
+};
+
+using pred_iterator = PredIterator<BasicBlock, Value::user_iterator>;
+using const_pred_iterator =
+    PredIterator<const BasicBlock, Value::const_user_iterator>;
+using pred_range = iterator_range<pred_iterator>;
+using const_pred_range = iterator_range<const_pred_iterator>;
+
+inline pred_iterator pred_begin(BasicBlock *BB) { return pred_iterator(BB); }
+inline const_pred_iterator pred_begin(const BasicBlock *BB) {
+  return const_pred_iterator(BB);
+}
+inline pred_iterator pred_end(BasicBlock *BB) { return pred_iterator(BB, true);}
+inline const_pred_iterator pred_end(const BasicBlock *BB) {
+  return const_pred_iterator(BB, true);
+}
+inline bool pred_empty(const BasicBlock *BB) {
+  return pred_begin(BB) == pred_end(BB);
+}
+/// Get the number of predecessors of \p BB. This is a linear time operation.
+/// Use \ref BasicBlock::hasNPredecessors() or hasNPredecessorsOrMore if able.
+inline unsigned pred_size(const BasicBlock *BB) {
+  return std::distance(pred_begin(BB), pred_end(BB));
+}
+inline pred_range predecessors(BasicBlock *BB) {
+  return pred_range(pred_begin(BB), pred_end(BB));
+}
+inline const_pred_range predecessors(const BasicBlock *BB) {
+  return const_pred_range(pred_begin(BB), pred_end(BB));
+}
+
+//===----------------------------------------------------------------------===//
+// Instruction and BasicBlock succ_iterator helpers
+//===----------------------------------------------------------------------===//
+
+template <class InstructionT, class BlockT>
+class SuccIterator
+    : public iterator_facade_base<SuccIterator<InstructionT, BlockT>,
+                                  std::random_access_iterator_tag, BlockT, int,
+                                  BlockT *, BlockT *> {
+public:
+  using difference_type = int;
+  using pointer = BlockT *;
+  using reference = BlockT *;
+
+private:
+  InstructionT *Inst;
+  int Idx;
+  using Self = SuccIterator<InstructionT, BlockT>;
+
+  inline bool index_is_valid(int Idx) {
+    // Note that we specially support the index of zero being valid even in the
+    // face of a null instruction.
+    return Idx >= 0 && (Idx == 0 || Idx <= (int)Inst->getNumSuccessors());
+  }
+
+  /// Proxy object to allow write access in operator[]
+  class SuccessorProxy {
+    Self It;
+
+  public:
+    explicit SuccessorProxy(const Self &It) : It(It) {}
+
+    SuccessorProxy(const SuccessorProxy &) = default;
+
+    SuccessorProxy &operator=(SuccessorProxy RHS) {
+      *this = reference(RHS);
+      return *this;
+    }
+
+    SuccessorProxy &operator=(reference RHS) {
+      It.Inst->setSuccessor(It.Idx, RHS);
+      return *this;
+    }
+
+    operator reference() const { return *It; }
+  };
+
+public:
+  // begin iterator
+  explicit inline SuccIterator(InstructionT *Inst) : Inst(Inst), Idx(0) {}
+  // end iterator
+  inline SuccIterator(InstructionT *Inst, bool) : Inst(Inst) {
+    if (Inst)
+      Idx = Inst->getNumSuccessors();
+    else
+      // Inst == NULL happens, if a basic block is not fully constructed and
+      // consequently getTerminator() returns NULL. In this case we construct
+      // a SuccIterator which describes a basic block that has zero
+      // successors.
+      // Defining SuccIterator for incomplete and malformed CFGs is especially
+      // useful for debugging.
+      Idx = 0;
+  }
+
+  /// This is used to interface between code that wants to
+  /// operate on terminator instructions directly.
+  int getSuccessorIndex() const { return Idx; }
+
+  inline bool operator==(const Self &x) const { return Idx == x.Idx; }
+
+  inline BlockT *operator*() const { return Inst->getSuccessor(Idx); }
+
+  // We use the basic block pointer directly for operator->.
+  inline BlockT *operator->() const { return operator*(); }
+
+  inline bool operator<(const Self &RHS) const {
+    assert(Inst == RHS.Inst && "Cannot compare iterators of different blocks!");
+    return Idx < RHS.Idx;
+  }
+
+  int operator-(const Self &RHS) const {
+    assert(Inst == RHS.Inst && "Cannot compare iterators of different blocks!");
+    return Idx - RHS.Idx;
+  }
+
+  inline Self &operator+=(int RHS) {
+    int NewIdx = Idx + RHS;
+    assert(index_is_valid(NewIdx) && "Iterator index out of bound");
+    Idx = NewIdx;
+    return *this;
+  }
+
+  inline Self &operator-=(int RHS) { return operator+=(-RHS); }
+
+  // Specially implement the [] operation using a proxy object to support
+  // assignment.
+  inline SuccessorProxy operator[](int Offset) {
+    Self TmpIt = *this;
+    TmpIt += Offset;
+    return SuccessorProxy(TmpIt);
+  }
+
+  /// Get the source BlockT of this iterator.
+  inline BlockT *getSource() {
+    assert(Inst && "Source not available, if basic block was malformed");
+    return Inst->getParent();
+  }
+};
+
+using succ_iterator = SuccIterator<Instruction, BasicBlock>;
+using const_succ_iterator = SuccIterator<const Instruction, const BasicBlock>;
+using succ_range = iterator_range<succ_iterator>;
+using const_succ_range = iterator_range<const_succ_iterator>;
+
+inline succ_iterator succ_begin(Instruction *I) { return succ_iterator(I); }
+inline const_succ_iterator succ_begin(const Instruction *I) {
+  return const_succ_iterator(I);
+}
+inline succ_iterator succ_end(Instruction *I) { return succ_iterator(I, true); }
+inline const_succ_iterator succ_end(const Instruction *I) {
+  return const_succ_iterator(I, true);
+}
+inline bool succ_empty(const Instruction *I) {
+  return succ_begin(I) == succ_end(I);
+}
+inline unsigned succ_size(const Instruction *I) {
+  return std::distance(succ_begin(I), succ_end(I));
+}
+inline succ_range successors(Instruction *I) {
+  return succ_range(succ_begin(I), succ_end(I));
+}
+inline const_succ_range successors(const Instruction *I) {
+  return const_succ_range(succ_begin(I), succ_end(I));
+}
+
+inline succ_iterator succ_begin(BasicBlock *BB) {
+  return succ_iterator(BB->getTerminator());
+}
+inline const_succ_iterator succ_begin(const BasicBlock *BB) {
+  return const_succ_iterator(BB->getTerminator());
+}
+inline succ_iterator succ_end(BasicBlock *BB) {
+  return succ_iterator(BB->getTerminator(), true);
+}
+inline const_succ_iterator succ_end(const BasicBlock *BB) {
+  return const_succ_iterator(BB->getTerminator(), true);
+}
+inline bool succ_empty(const BasicBlock *BB) {
+  return succ_begin(BB) == succ_end(BB);
+}
+inline unsigned succ_size(const BasicBlock *BB) {
+  return std::distance(succ_begin(BB), succ_end(BB));
+}
+inline succ_range successors(BasicBlock *BB) {
+  return succ_range(succ_begin(BB), succ_end(BB));
+}
+inline const_succ_range successors(const BasicBlock *BB) {
+  return const_succ_range(succ_begin(BB), succ_end(BB));
+}
+
+//===--------------------------------------------------------------------===//
+// GraphTraits specializations for basic block graphs (CFGs)
+//===--------------------------------------------------------------------===//
+
+// Provide specializations of GraphTraits to be able to treat a function as a
+// graph of basic blocks...
+
+template <> struct GraphTraits<BasicBlock*> {
+  using NodeRef = BasicBlock *;
+  using ChildIteratorType = succ_iterator;
+
+  static NodeRef getEntryNode(BasicBlock *BB) { return BB; }
+  static ChildIteratorType child_begin(NodeRef N) { return succ_begin(N); }
+  static ChildIteratorType child_end(NodeRef N) { return succ_end(N); }
+};
+
+template <> struct GraphTraits<const BasicBlock*> {
+  using NodeRef = const BasicBlock *;
+  using ChildIteratorType = const_succ_iterator;
+
+  static NodeRef getEntryNode(const BasicBlock *BB) { return BB; }
+
+  static ChildIteratorType child_begin(NodeRef N) { return succ_begin(N); }
+  static ChildIteratorType child_end(NodeRef N) { return succ_end(N); }
+};
+
+// Provide specializations of GraphTraits to be able to treat a function as a
+// graph of basic blocks... and to walk it in inverse order.  Inverse order for
+// a function is considered to be when traversing the predecessor edges of a BB
+// instead of the successor edges.
+//
+template <> struct GraphTraits<Inverse<BasicBlock*>> {
+  using NodeRef = BasicBlock *;
+  using ChildIteratorType = pred_iterator;
+
+  static NodeRef getEntryNode(Inverse<BasicBlock *> G) { return G.Graph; }
+  static ChildIteratorType child_begin(NodeRef N) { return pred_begin(N); }
+  static ChildIteratorType child_end(NodeRef N) { return pred_end(N); }
+};
+
+template <> struct GraphTraits<Inverse<const BasicBlock*>> {
+  using NodeRef = const BasicBlock *;
+  using ChildIteratorType = const_pred_iterator;
+
+  static NodeRef getEntryNode(Inverse<const BasicBlock *> G) { return G.Graph; }
+  static ChildIteratorType child_begin(NodeRef N) { return pred_begin(N); }
+  static ChildIteratorType child_end(NodeRef N) { return pred_end(N); }
+};
+
+//===--------------------------------------------------------------------===//
+// GraphTraits specializations for function basic block graphs (CFGs)
+//===--------------------------------------------------------------------===//
+
+// Provide specializations of GraphTraits to be able to treat a function as a
+// graph of basic blocks... these are the same as the basic block iterators,
+// except that the root node is implicitly the first node of the function.
+//
+template <> struct GraphTraits<Function*> : public GraphTraits<BasicBlock*> {
+  static NodeRef getEntryNode(Function *F) { return &F->getEntryBlock(); }
+
+  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
+  using nodes_iterator = pointer_iterator<Function::iterator>;
+
+  static nodes_iterator nodes_begin(Function *F) {
+    return nodes_iterator(F->begin());
+  }
+
+  static nodes_iterator nodes_end(Function *F) {
+    return nodes_iterator(F->end());
+  }
+
+  static size_t size(Function *F) { return F->size(); }
+};
+template <> struct GraphTraits<const Function*> :
+  public GraphTraits<const BasicBlock*> {
+  static NodeRef getEntryNode(const Function *F) { return &F->getEntryBlock(); }
+
+  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
+  using nodes_iterator = pointer_iterator<Function::const_iterator>;
+
+  static nodes_iterator nodes_begin(const Function *F) {
+    return nodes_iterator(F->begin());
+  }
+
+  static nodes_iterator nodes_end(const Function *F) {
+    return nodes_iterator(F->end());
+  }
+
+  static size_t size(const Function *F) { return F->size(); }
+};
+
+// Provide specializations of GraphTraits to be able to treat a function as a
+// graph of basic blocks... and to walk it in inverse order.  Inverse order for
+// a function is considered to be when traversing the predecessor edges of a BB
+// instead of the successor edges.
+//
+template <> struct GraphTraits<Inverse<Function*>> :
+  public GraphTraits<Inverse<BasicBlock*>> {
+  static NodeRef getEntryNode(Inverse<Function *> G) {
+    return &G.Graph->getEntryBlock();
+  }
+};
+template <> struct GraphTraits<Inverse<const Function*>> :
+  public GraphTraits<Inverse<const BasicBlock*>> {
+  static NodeRef getEntryNode(Inverse<const Function *> G) {
+    return &G.Graph->getEntryBlock();
+  }
+};
+
+} // end namespace llvm
+
+#endif // LLVM_IR_CFG_H