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