| //===- 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/InstrTypes.h" |
| #include "llvm/IR/Value.h" |
| #include "llvm/Support/Casting.h" |
| #include "llvm/Support/type_traits.h" |
| #include <cassert> |
| #include <cstddef> |
| #include <iterator> |
| |
| namespace llvm { |
| |
| //===----------------------------------------------------------------------===// |
| // BasicBlock pred_iterator definition |
| //===----------------------------------------------------------------------===// |
| |
| template <class Ptr, class USE_iterator> // Predecessor Iterator |
| class PredIterator : public std::iterator<std::forward_iterator_tag, |
| Ptr, ptrdiff_t, Ptr*, Ptr*> { |
| using super = |
| std::iterator<std::forward_iterator_tag, Ptr, ptrdiff_t, Ptr*, Ptr*>; |
| 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: |
| using pointer = typename super::pointer; |
| using reference = typename super::reference; |
| |
| 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 pred_const_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 pred_const_range predecessors(const BasicBlock *BB) { |
| return pred_const_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 succ_const_iterator = SuccIterator<const Instruction, const BasicBlock>; |
| using succ_range = iterator_range<succ_iterator>; |
| using succ_const_range = iterator_range<succ_const_iterator>; |
| |
| inline succ_iterator succ_begin(Instruction *I) { return succ_iterator(I); } |
| inline succ_const_iterator succ_begin(const Instruction *I) { |
| return succ_const_iterator(I); |
| } |
| inline succ_iterator succ_end(Instruction *I) { return succ_iterator(I, true); } |
| inline succ_const_iterator succ_end(const Instruction *I) { |
| return succ_const_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 succ_const_range successors(const Instruction *I) { |
| return succ_const_range(succ_begin(I), succ_end(I)); |
| } |
| |
| inline succ_iterator succ_begin(BasicBlock *BB) { |
| return succ_iterator(BB->getTerminator()); |
| } |
| inline succ_const_iterator succ_begin(const BasicBlock *BB) { |
| return succ_const_iterator(BB->getTerminator()); |
| } |
| inline succ_iterator succ_end(BasicBlock *BB) { |
| return succ_iterator(BB->getTerminator(), true); |
| } |
| inline succ_const_iterator succ_end(const BasicBlock *BB) { |
| return succ_const_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 succ_const_range successors(const BasicBlock *BB) { |
| return succ_const_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 = succ_const_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 |