1 //===- IntervalIterator.h - Interval Iterator Declaration -------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines an iterator that enumerates the intervals in a control flow
11 // graph of some sort. This iterator is parametric, allowing iterator over the
12 // following types of graphs:
14 // 1. A Function* object, composed of BasicBlock nodes.
15 // 2. An IntervalPartition& object, composed of Interval nodes.
17 // This iterator is defined to walk the control flow graph, returning intervals
18 // in depth first order. These intervals are completely filled in except for
19 // the predecessor fields (the successor information is filled in however).
21 // By default, the intervals created by this iterator are deleted after they
22 // are no longer any use to the iterator. This behavior can be changed by
23 // passing a false value into the intervals_begin() function. This causes the
24 // IOwnMem member to be set, and the intervals to not be deleted.
26 // It is only safe to use this if all of the intervals are deleted by the caller
27 // and all of the intervals are processed. However, the user of the iterator is
28 // not allowed to modify or delete the intervals until after the iterator has
29 // been used completely. The IntervalPartition class uses this functionality.
31 //===----------------------------------------------------------------------===//
33 #ifndef LLVM_ANALYSIS_INTERVALITERATOR_H
34 #define LLVM_ANALYSIS_INTERVALITERATOR_H
36 #include "llvm/ADT/GraphTraits.h"
37 #include "llvm/Analysis/Interval.h"
38 #include "llvm/Analysis/IntervalPartition.h"
39 #include "llvm/IR/CFG.h"
40 #include "llvm/IR/Function.h"
41 #include "llvm/Support/ErrorHandling.h"
53 // getNodeHeader - Given a source graph node and the source graph, return the
54 // BasicBlock that is the header node. This is the opposite of
55 // getSourceGraphNode.
56 inline BasicBlock *getNodeHeader(BasicBlock *BB) { return BB; }
57 inline BasicBlock *getNodeHeader(Interval *I) { return I->getHeaderNode(); }
59 // getSourceGraphNode - Given a BasicBlock and the source graph, return the
60 // source graph node that corresponds to the BasicBlock. This is the opposite
62 inline BasicBlock *getSourceGraphNode(Function *, BasicBlock *BB) {
65 inline Interval *getSourceGraphNode(IntervalPartition *IP, BasicBlock *BB) {
66 return IP->getBlockInterval(BB);
69 // addNodeToInterval - This method exists to assist the generic ProcessNode
70 // with the task of adding a node to the new interval, depending on the
71 // type of the source node. In the case of a CFG source graph (BasicBlock
72 // case), the BasicBlock itself is added to the interval.
73 inline void addNodeToInterval(Interval *Int, BasicBlock *BB) {
74 Int->Nodes.push_back(BB);
77 // addNodeToInterval - This method exists to assist the generic ProcessNode
78 // with the task of adding a node to the new interval, depending on the
79 // type of the source node. In the case of a CFG source graph (BasicBlock
80 // case), the BasicBlock itself is added to the interval. In the case of
81 // an IntervalPartition source graph (Interval case), all of the member
82 // BasicBlocks are added to the interval.
83 inline void addNodeToInterval(Interval *Int, Interval *I) {
84 // Add all of the nodes in I as new nodes in Int.
85 Int->Nodes.insert(Int->Nodes.end(), I->Nodes.begin(), I->Nodes.end());
88 template<class NodeTy, class OrigContainer_t, class GT = GraphTraits<NodeTy *>,
89 class IGT = GraphTraits<Inverse<NodeTy *>>>
90 class IntervalIterator {
91 std::vector<std::pair<Interval *, typename Interval::succ_iterator>> IntStack;
92 std::set<BasicBlock *> Visited;
93 OrigContainer_t *OrigContainer;
94 bool IOwnMem; // If True, delete intervals when done with them
95 // See file header for conditions of use
98 using iterator_category = std::forward_iterator_tag;
100 IntervalIterator() = default; // End iterator, empty stack
102 IntervalIterator(Function *M, bool OwnMemory) : IOwnMem(OwnMemory) {
104 if (!ProcessInterval(&M->front())) {
105 llvm_unreachable("ProcessInterval should never fail for first interval!");
109 IntervalIterator(IntervalIterator &&x)
110 : IntStack(std::move(x.IntStack)), Visited(std::move(x.Visited)),
111 OrigContainer(x.OrigContainer), IOwnMem(x.IOwnMem) {
115 IntervalIterator(IntervalPartition &IP, bool OwnMemory) : IOwnMem(OwnMemory) {
117 if (!ProcessInterval(IP.getRootInterval())) {
118 llvm_unreachable("ProcessInterval should never fail for first interval!");
122 ~IntervalIterator() {
124 while (!IntStack.empty()) {
130 bool operator==(const IntervalIterator &x) const {
131 return IntStack == x.IntStack;
133 bool operator!=(const IntervalIterator &x) const { return !(*this == x); }
135 const Interval *operator*() const { return IntStack.back().first; }
136 Interval *operator*() { return IntStack.back().first; }
137 const Interval *operator->() const { return operator*(); }
138 Interval *operator->() { return operator*(); }
140 IntervalIterator &operator++() { // Preincrement
141 assert(!IntStack.empty() && "Attempting to use interval iterator at end!");
143 // All of the intervals on the stack have been visited. Try visiting
144 // their successors now.
145 Interval::succ_iterator &SuccIt = IntStack.back().second,
146 EndIt = succ_end(IntStack.back().first);
147 while (SuccIt != EndIt) { // Loop over all interval succs
148 bool Done = ProcessInterval(getSourceGraphNode(OrigContainer, *SuccIt));
149 ++SuccIt; // Increment iterator
150 if (Done) return *this; // Found a new interval! Use it!
153 // Free interval memory... if necessary
154 if (IOwnMem) delete IntStack.back().first;
156 // We ran out of successors for this interval... pop off the stack
158 } while (!IntStack.empty());
163 IntervalIterator operator++(int) { // Postincrement
164 IntervalIterator tmp = *this;
170 // ProcessInterval - This method is used during the construction of the
171 // interval graph. It walks through the source graph, recursively creating
172 // an interval per invocation until the entire graph is covered. This uses
173 // the ProcessNode method to add all of the nodes to the interval.
175 // This method is templated because it may operate on two different source
176 // graphs: a basic block graph, or a preexisting interval graph.
177 bool ProcessInterval(NodeTy *Node) {
178 BasicBlock *Header = getNodeHeader(Node);
179 if (!Visited.insert(Header).second)
182 Interval *Int = new Interval(Header);
184 // Check all of our successors to see if they are in the interval...
185 for (typename GT::ChildIteratorType I = GT::child_begin(Node),
186 E = GT::child_end(Node); I != E; ++I)
187 ProcessNode(Int, getSourceGraphNode(OrigContainer, *I));
189 IntStack.push_back(std::make_pair(Int, succ_begin(Int)));
193 // ProcessNode - This method is called by ProcessInterval to add nodes to the
194 // interval being constructed, and it is also called recursively as it walks
195 // the source graph. A node is added to the current interval only if all of
196 // its predecessors are already in the graph. This also takes care of keeping
197 // the successor set of an interval up to date.
199 // This method is templated because it may operate on two different source
200 // graphs: a basic block graph, or a preexisting interval graph.
201 void ProcessNode(Interval *Int, NodeTy *Node) {
202 assert(Int && "Null interval == bad!");
203 assert(Node && "Null Node == bad!");
205 BasicBlock *NodeHeader = getNodeHeader(Node);
207 if (Visited.count(NodeHeader)) { // Node already been visited?
208 if (Int->contains(NodeHeader)) { // Already in this interval...
210 } else { // In other interval, add as successor
211 if (!Int->isSuccessor(NodeHeader)) // Add only if not already in set
212 Int->Successors.push_back(NodeHeader);
214 } else { // Otherwise, not in interval yet
215 for (typename IGT::ChildIteratorType I = IGT::child_begin(Node),
216 E = IGT::child_end(Node); I != E; ++I) {
217 if (!Int->contains(*I)) { // If pred not in interval, we can't be
218 if (!Int->isSuccessor(NodeHeader)) // Add only if not already in set
219 Int->Successors.push_back(NodeHeader);
220 return; // See you later
224 // If we get here, then all of the predecessors of BB are in the interval
225 // already. In this case, we must add BB to the interval!
226 addNodeToInterval(Int, Node);
227 Visited.insert(NodeHeader); // The node has now been visited!
229 if (Int->isSuccessor(NodeHeader)) {
230 // If we were in the successor list from before... remove from succ list
231 Int->Successors.erase(std::remove(Int->Successors.begin(),
232 Int->Successors.end(), NodeHeader),
233 Int->Successors.end());
236 // Now that we have discovered that Node is in the interval, perhaps some
237 // of its successors are as well?
238 for (typename GT::ChildIteratorType It = GT::child_begin(Node),
239 End = GT::child_end(Node); It != End; ++It)
240 ProcessNode(Int, getSourceGraphNode(OrigContainer, *It));
245 using function_interval_iterator = IntervalIterator<BasicBlock, Function>;
246 using interval_part_interval_iterator =
247 IntervalIterator<Interval, IntervalPartition>;
249 inline function_interval_iterator intervals_begin(Function *F,
250 bool DeleteInts = true) {
251 return function_interval_iterator(F, DeleteInts);
253 inline function_interval_iterator intervals_end(Function *) {
254 return function_interval_iterator();
257 inline interval_part_interval_iterator
258 intervals_begin(IntervalPartition &IP, bool DeleteIntervals = true) {
259 return interval_part_interval_iterator(IP, DeleteIntervals);
262 inline interval_part_interval_iterator intervals_end(IntervalPartition &IP) {
263 return interval_part_interval_iterator();
266 } // end namespace llvm
268 #endif // LLVM_ANALYSIS_INTERVALITERATOR_H