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//===-- llvm/Support/CFG.h - Process LLVM structures as graphs --*- C++ -*-===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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// This file defines specializations of GraphTraits that allow Function and
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// BasicBlock graphs to be treated as proper graphs for generic algorithms.
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_CFG_H
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#define LLVM_SUPPORT_CFG_H
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#include "llvm/ADT/GraphTraits.h"
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#include "llvm/Function.h"
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#include "llvm/InstrTypes.h"
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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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typedef std::iterator<std::forward_iterator_tag, _Ptr, ptrdiff_t> super;
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typedef PredIterator<_Ptr,_USE_iterator> _Self;
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typedef typename super::pointer pointer;
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inline void advancePastNonTerminators() {
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// Loop to ignore non terminator uses (for example PHI nodes)...
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while (!It.atEnd() && !isa<TerminatorInst>(*It))
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inline PredIterator(_Ptr *bb) : It(bb->use_begin()) {
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advancePastNonTerminators();
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inline PredIterator(_Ptr *bb, bool) : It(bb->use_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 pointer operator*() const {
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assert(!It.atEnd() && "pred_iterator out of range!");
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return cast<TerminatorInst>(*It)->getParent();
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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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inline _Self operator++(int) { // Postincrement
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_Self tmp = *this; ++*this; return tmp;
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typedef PredIterator<BasicBlock, Value::use_iterator> pred_iterator;
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typedef PredIterator<const BasicBlock,
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Value::use_const_iterator> pred_const_iterator;
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inline pred_iterator pred_begin(BasicBlock *BB) { return pred_iterator(BB); }
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inline pred_const_iterator pred_begin(const BasicBlock *BB) {
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return pred_const_iterator(BB);
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inline pred_iterator pred_end(BasicBlock *BB) { return pred_iterator(BB, true);}
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inline pred_const_iterator pred_end(const BasicBlock *BB) {
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return pred_const_iterator(BB, true);
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//===----------------------------------------------------------------------===//
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// BasicBlock succ_iterator definition
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//===----------------------------------------------------------------------===//
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template <class Term_, class BB_> // Successor Iterator
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class SuccIterator : public std::iterator<std::bidirectional_iterator_tag,
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typedef std::iterator<std::bidirectional_iterator_tag, BB_, ptrdiff_t> super;
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typedef SuccIterator<Term_, BB_> _Self;
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typedef typename super::pointer pointer;
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// TODO: This can be random access iterator, only operator[] missing.
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inline SuccIterator(Term_ T) : Term(T), idx(0) { // begin iterator
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assert(T && "getTerminator returned null!");
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inline SuccIterator(Term_ T, bool) // end iterator
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: Term(T), idx(Term->getNumSuccessors()) {
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assert(T && "getTerminator returned null!");
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inline const _Self &operator=(const _Self &I) {
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assert(Term == I.Term &&"Cannot assign iterators to two different blocks!");
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inline bool index_is_valid (int idx) {
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return idx >= 0 && (unsigned) idx < Term->getNumSuccessors();
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/// getSuccessorIndex - This is used to interface between code that wants to
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/// operate on terminator instructions directly.
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unsigned getSuccessorIndex() const { return idx; }
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inline bool operator==(const _Self& x) const { return idx == x.idx; }
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inline bool operator!=(const _Self& x) const { return !operator==(x); }
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inline pointer operator*() const { return Term->getSuccessor(idx); }
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inline pointer operator->() const { return operator*(); }
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inline _Self& operator++() { ++idx; return *this; } // Preincrement
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inline _Self operator++(int) { // Postincrement
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_Self tmp = *this; ++*this; return tmp;
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inline _Self& operator--() { --idx; return *this; } // Predecrement
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inline _Self operator--(int) { // Postdecrement
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_Self tmp = *this; --*this; return tmp;
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inline bool operator<(const _Self& x) const {
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assert(Term == x.Term && "Cannot compare iterators of different blocks!");
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inline bool operator<=(const _Self& x) const {
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assert(Term == x.Term && "Cannot compare iterators of different blocks!");
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inline bool operator>=(const _Self& x) const {
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assert(Term == x.Term && "Cannot compare iterators of different blocks!");
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inline bool operator>(const _Self& x) const {
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assert(Term == x.Term && "Cannot compare iterators of different blocks!");
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inline _Self& operator+=(int Right) {
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unsigned new_idx = idx + Right;
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assert(index_is_valid(new_idx) && "Iterator index out of bound");
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inline _Self operator+(int Right) {
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inline _Self& operator-=(int Right) {
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return operator+=(-Right);
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inline _Self operator-(int Right) {
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return operator+(-Right);
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inline int operator-(const _Self& x) {
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assert(Term == x.Term && "Cannot work on iterators of different blocks!");
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int distance = idx - x.idx;
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// This works for read access, however write access is difficult as changes
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// to Term are only possible with Term->setSuccessor(idx). Pointers that can
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// be modified are not available.
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// inline pointer operator[](int offset) {
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// _Self tmp = *this;
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// return tmp.operator*();
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/// Get the source BB of this iterator.
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inline BB_ *getSource() {
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return Term->getParent();
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typedef SuccIterator<TerminatorInst*, BasicBlock> succ_iterator;
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typedef SuccIterator<const TerminatorInst*,
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const BasicBlock> succ_const_iterator;
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inline succ_iterator succ_begin(BasicBlock *BB) {
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return succ_iterator(BB->getTerminator());
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inline succ_const_iterator succ_begin(const BasicBlock *BB) {
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return succ_const_iterator(BB->getTerminator());
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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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inline succ_const_iterator succ_end(const BasicBlock *BB) {
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return succ_const_iterator(BB->getTerminator(), true);
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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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typedef BasicBlock NodeType;
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typedef succ_iterator ChildIteratorType;
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static NodeType *getEntryNode(BasicBlock *BB) { return BB; }
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static inline ChildIteratorType child_begin(NodeType *N) {
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return succ_begin(N);
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static inline ChildIteratorType child_end(NodeType *N) {
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template <> struct GraphTraits<const BasicBlock*> {
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typedef const BasicBlock NodeType;
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typedef succ_const_iterator ChildIteratorType;
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static NodeType *getEntryNode(const BasicBlock *BB) { return BB; }
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static inline ChildIteratorType child_begin(NodeType *N) {
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return succ_begin(N);
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static inline ChildIteratorType child_end(NodeType *N) {
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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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template <> struct GraphTraits<Inverse<BasicBlock*> > {
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typedef BasicBlock NodeType;
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typedef pred_iterator ChildIteratorType;
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static NodeType *getEntryNode(Inverse<BasicBlock *> G) { return G.Graph; }
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static inline ChildIteratorType child_begin(NodeType *N) {
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return pred_begin(N);
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static inline ChildIteratorType child_end(NodeType *N) {
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template <> struct GraphTraits<Inverse<const BasicBlock*> > {
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typedef const BasicBlock NodeType;
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typedef pred_const_iterator ChildIteratorType;
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static NodeType *getEntryNode(Inverse<const BasicBlock*> G) {
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static inline ChildIteratorType child_begin(NodeType *N) {
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return pred_begin(N);
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static inline ChildIteratorType child_end(NodeType *N) {
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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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template <> struct GraphTraits<Function*> : public GraphTraits<BasicBlock*> {
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static NodeType *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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typedef Function::iterator nodes_iterator;
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static nodes_iterator nodes_begin(Function *F) { return F->begin(); }
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static nodes_iterator nodes_end (Function *F) { return F->end(); }
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template <> struct GraphTraits<const Function*> :
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public GraphTraits<const BasicBlock*> {
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static NodeType *getEntryNode(const 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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typedef Function::const_iterator nodes_iterator;
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static nodes_iterator nodes_begin(const Function *F) { return F->begin(); }
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static nodes_iterator nodes_end (const Function *F) { return F->end(); }
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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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template <> struct GraphTraits<Inverse<Function*> > :
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public GraphTraits<Inverse<BasicBlock*> > {
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static NodeType *getEntryNode(Inverse<Function*> G) {
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return &G.Graph->getEntryBlock();
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template <> struct GraphTraits<Inverse<const Function*> > :
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public GraphTraits<Inverse<const BasicBlock*> > {
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static NodeType *getEntryNode(Inverse<const Function *> G) {
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return &G.Graph->getEntryBlock();
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} // End llvm namespace