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[ADT] Add a generic breadth-first-search graph iterator.
This will be used in LCSSA to speed up the canonicalization. Differential Revision: https://reviews.llvm.org/D31694 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@299660 91177308-0d34-0410-b5e6-96231b3b80d8
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include/llvm/ADT/BreadthFirstIterator.h
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include/llvm/ADT/BreadthFirstIterator.h
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//===- llvm/ADT/BreadthFirstIterator.h - Breadth First iterator -*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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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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//===----------------------------------------------------------------------===//
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//
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// This file builds on the ADT/GraphTraits.h file to build a generic breadth
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// first graph iterator. This file exposes the following functions/types:
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//
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// bf_begin/bf_end/bf_iterator
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// * Normal breadth-first iteration - visit a graph level-by-level.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_BREADTHFIRSTITERATOR_H
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#define LLVM_ADT_BREADTHFIRSTITERATOR_H
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#include "llvm/ADT/GraphTraits.h"
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#include "llvm/ADT/None.h"
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#include "llvm/ADT/Optional.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/iterator_range.h"
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#include <iterator>
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#include <queue>
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#include <set>
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#include <utility>
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namespace llvm {
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// bf_iterator_storage - A private class which is used to figure out where to
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// store the visited set. We only provide a non-external variant for now.
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template <class SetType> class bf_iterator_storage {
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public:
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SetType Visited;
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};
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// The visited state for the iteration is a simple set.
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template <typename NodeRef, unsigned SmallSize = 8>
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using bf_iterator_default_set = SmallPtrSet<NodeRef, SmallSize>;
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// Generic Breadth first search iterator.
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template <class GraphT,
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class SetType =
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bf_iterator_default_set<typename GraphTraits<GraphT>::NodeRef>,
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class GT = GraphTraits<GraphT>>
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class bf_iterator
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: public std::iterator<std::forward_iterator_tag, typename GT::NodeRef>,
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public bf_iterator_storage<SetType> {
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typedef std::iterator<std::forward_iterator_tag, typename GT::NodeRef> super;
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typedef typename GT::NodeRef NodeRef;
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typedef typename GT::ChildIteratorType ChildItTy;
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// First element is the node reference, second is the next child to visit.
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typedef std::pair<NodeRef, Optional<ChildItTy>> QueueElement;
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// Visit queue - used to maintain BFS ordering.
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// Optional<> because we need markers for levels.
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std::queue<Optional<QueueElement>> VisitQueue;
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// Current level.
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unsigned Level;
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private:
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inline bf_iterator(NodeRef Node) {
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this->Visited.insert(Node);
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Level = 0;
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// Also, insert a dummy node as marker.
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VisitQueue.push(QueueElement(Node, None));
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VisitQueue.push(None);
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}
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inline bf_iterator() = default;
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inline void toNext() {
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Optional<QueueElement> Head = VisitQueue.front();
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QueueElement H = Head.getValue();
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NodeRef Node = H.first;
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Optional<ChildItTy> &ChildIt = H.second;
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if (!ChildIt)
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ChildIt.emplace(GT::child_begin(Node));
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while (*ChildIt != GT::child_end(Node)) {
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NodeRef Next = *(*ChildIt)++;
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// Already visited?
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if (this->Visited.insert(Next).second)
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VisitQueue.push(QueueElement(Next, None));
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}
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VisitQueue.pop();
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// Go to the next element skipping markers if needed.
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if (!VisitQueue.empty()) {
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Head = VisitQueue.front();
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if (Head != None)
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return;
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Level += 1;
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VisitQueue.pop();
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// Don't push another marker if this is the last
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// element.
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if (!VisitQueue.empty())
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VisitQueue.push(None);
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}
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}
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public:
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typedef typename super::pointer pointer;
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// Provide static begin and end methods as our public "constructors"
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static bf_iterator begin(const GraphT &G) {
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return bf_iterator(GT::getEntryNode(G));
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}
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static bf_iterator end(const GraphT &G) { return bf_iterator(); }
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bool operator==(const bf_iterator &RHS) const {
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assert(VisitQueue.size() == 0);
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return VisitQueue == RHS.VisitQueue;
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}
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bool operator!=(const bf_iterator &RHS) const { return !(*this == RHS); }
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const NodeRef &operator*() const { return VisitQueue.front()->first; }
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// This is a nonstandard operator-> that dereferenfces the pointer an extra
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// time so that you can actually call methods on the node, because the
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// contained type is a pointer.
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NodeRef operator->() const { return **this; }
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bf_iterator &operator++() { // Pre-increment
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toNext();
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return *this;
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}
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bf_iterator operator++(int) { // Post-increment
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bf_iterator ItCopy = *this;
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++*this;
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return ItCopy;
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}
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unsigned getLevel() const { return Level; }
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};
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// Provide global constructors that automatically figure out correct types.
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template <class T> bf_iterator<T> bf_begin(const T &G) {
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return bf_iterator<T>::begin(G);
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}
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template <class T> bf_iterator<T> bf_end(const T &G) {
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return bf_iterator<T>::end(G);
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}
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// Provide an accessor method to use them in range-based patterns.
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template <class T> iterator_range<bf_iterator<T>> breadth_first(const T &G) {
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return make_range(bf_begin(G), bf_end(G));
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}
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} // end namespace llvm
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#endif // LLVM_ADT_BREADTHFIRSTITERATOR_H
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unittests/ADT/BreadthFirstIteratorTest.cpp
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unittests/ADT/BreadthFirstIteratorTest.cpp
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//=== llvm/unittest/ADT/BreadthFirstIteratorTest.cpp - BFS iterator tests -===//
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//
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// The LLVM Compiler Infrastructure
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//
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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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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/BreadthFirstIterator.h"
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#include "TestGraph.h"
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#include "gtest/gtest.h"
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using namespace llvm;
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namespace llvm {
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TEST(BreadthFristIteratorTest, Basic) {
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typedef bf_iterator<Graph<4>> BFIter;
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Graph<4> G;
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G.AddEdge(0, 1);
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G.AddEdge(0, 2);
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G.AddEdge(1, 3);
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auto It = BFIter::begin(G);
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auto End = BFIter::end(G);
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EXPECT_EQ(It.getLevel(), 0U);
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EXPECT_EQ(*It, G.AccessNode(0));
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++It;
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EXPECT_EQ(It.getLevel(), 1U);
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EXPECT_EQ(*It, G.AccessNode(1));
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++It;
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EXPECT_EQ(It.getLevel(), 1U);
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EXPECT_EQ(*It, G.AccessNode(2));
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++It;
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EXPECT_EQ(It.getLevel(), 2U);
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EXPECT_EQ(*It, G.AccessNode(3));
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++It;
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EXPECT_EQ(It, End);
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}
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TEST(BreadthFristIteratorTest, Cycle) {
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typedef bf_iterator<Graph<4>> BFIter;
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Graph<4> G;
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G.AddEdge(0, 1);
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G.AddEdge(1, 0);
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G.AddEdge(1, 2);
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G.AddEdge(2, 1);
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G.AddEdge(2, 1);
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G.AddEdge(2, 3);
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G.AddEdge(3, 2);
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G.AddEdge(3, 1);
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G.AddEdge(3, 0);
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auto It = BFIter::begin(G);
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auto End = BFIter::end(G);
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EXPECT_EQ(It.getLevel(), 0U);
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EXPECT_EQ(*It, G.AccessNode(0));
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++It;
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EXPECT_EQ(It.getLevel(), 1U);
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EXPECT_EQ(*It, G.AccessNode(1));
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++It;
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EXPECT_EQ(It.getLevel(), 2U);
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EXPECT_EQ(*It, G.AccessNode(2));
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++It;
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EXPECT_EQ(It.getLevel(), 3U);
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EXPECT_EQ(*It, G.AccessNode(3));
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++It;
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EXPECT_EQ(It, End);
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}
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} // end namespace llvm
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ArrayRefTest.cpp
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BitmaskEnumTest.cpp
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BitVectorTest.cpp
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BreadthFirstIteratorTest.cpp
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BumpPtrListTest.cpp
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DAGDeltaAlgorithmTest.cpp
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DeltaAlgorithmTest.cpp
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