1 //===- IntervalIterator.h - Interval Iterator Declaration --------*- C++ -*--=//
3 // This file defines an iterator that enumerates the intervals in a control flow
4 // graph of some sort. This iterator is parametric, allowing iterator over the
5 // following types of graphs:
7 // 1. A Function* object, composed of BasicBlock nodes.
8 // 2. An IntervalPartition& object, composed of Interval nodes.
10 // This iterator is defined to walk the control flow graph, returning intervals
11 // in depth first order. These intervals are completely filled in except for
12 // the predecessor fields (the successor information is filled in however).
14 // By default, the intervals created by this iterator are deleted after they
15 // are no longer any use to the iterator. This behavior can be changed by
16 // passing a false value into the intervals_begin() function. This causes the
17 // IOwnMem member to be set, and the intervals to not be deleted.
19 // It is only safe to use this if all of the intervals are deleted by the caller
20 // and all of the intervals are processed. However, the user of the iterator is
21 // not allowed to modify or delete the intervals until after the iterator has
22 // been used completely. The IntervalPartition class uses this functionality.
24 //===----------------------------------------------------------------------===//
26 #ifndef LLVM_INTERVAL_ITERATOR_H
27 #define LLVM_INTERVAL_ITERATOR_H
29 #include "llvm/Analysis/IntervalPartition.h"
30 #include "llvm/Function.h"
31 #include "llvm/BasicBlock.h"
32 #include "llvm/Support/CFG.h"
38 // getNodeHeader - Given a source graph node and the source graph, return the
39 // BasicBlock that is the header node. This is the opposite of
40 // getSourceGraphNode.
42 inline BasicBlock *getNodeHeader(BasicBlock *BB) { return BB; }
43 inline BasicBlock *getNodeHeader(Interval *I) { return I->getHeaderNode(); }
45 // getSourceGraphNode - Given a BasicBlock and the source graph, return the
46 // source graph node that corresponds to the BasicBlock. This is the opposite
49 inline BasicBlock *getSourceGraphNode(Function *, BasicBlock *BB) {
52 inline Interval *getSourceGraphNode(IntervalPartition *IP, BasicBlock *BB) {
53 return IP->getBlockInterval(BB);
56 // addNodeToInterval - This method exists to assist the generic ProcessNode
57 // with the task of adding a node to the new interval, depending on the
58 // type of the source node. In the case of a CFG source graph (BasicBlock
59 // case), the BasicBlock itself is added to the interval.
61 inline void addNodeToInterval(Interval *Int, BasicBlock *BB) {
62 Int->Nodes.push_back(BB);
65 // addNodeToInterval - This method exists to assist the generic ProcessNode
66 // with the task of adding a node to the new interval, depending on the
67 // type of the source node. In the case of a CFG source graph (BasicBlock
68 // case), the BasicBlock itself is added to the interval. In the case of
69 // an IntervalPartition source graph (Interval case), all of the member
70 // BasicBlocks are added to the interval.
72 inline void addNodeToInterval(Interval *Int, Interval *I) {
73 // Add all of the nodes in I as new nodes in Int.
74 copy(I->Nodes.begin(), I->Nodes.end(), back_inserter(Int->Nodes));
81 template<class NodeTy, class OrigContainer_t>
82 class IntervalIterator {
83 std::stack<std::pair<Interval*, typename Interval::succ_iterator> > IntStack;
84 std::set<BasicBlock*> Visited;
85 OrigContainer_t *OrigContainer;
86 bool IOwnMem; // If True, delete intervals when done with them
87 // See file header for conditions of use
89 typedef BasicBlock* _BB;
91 typedef IntervalIterator<NodeTy, OrigContainer_t> _Self;
92 typedef std::forward_iterator_tag iterator_category;
94 IntervalIterator() {} // End iterator, empty stack
95 IntervalIterator(Function *M, bool OwnMemory) : IOwnMem(OwnMemory) {
97 if (!ProcessInterval(&M->front())) {
98 assert(0 && "ProcessInterval should never fail for first interval!");
102 IntervalIterator(IntervalPartition &IP, bool OwnMemory) : IOwnMem(OwnMemory) {
104 if (!ProcessInterval(IP.getRootInterval())) {
105 assert(0 && "ProcessInterval should never fail for first interval!");
109 inline ~IntervalIterator() {
111 while (!IntStack.empty()) {
117 inline bool operator==(const _Self& x) const { return IntStack == x.IntStack;}
118 inline bool operator!=(const _Self& x) const { return !operator==(x); }
120 inline const Interval *operator*() const { return IntStack.top().first; }
121 inline Interval *operator*() { return IntStack.top().first; }
122 inline const Interval *operator->() const { return operator*(); }
123 inline Interval *operator->() { return operator*(); }
125 _Self& operator++() { // Preincrement
126 assert(!IntStack.empty() && "Attempting to use interval iterator at end!");
128 // All of the intervals on the stack have been visited. Try visiting
129 // their successors now.
130 Interval::succ_iterator &SuccIt = IntStack.top().second,
131 EndIt = succ_end(IntStack.top().first);
132 while (SuccIt != EndIt) { // Loop over all interval succs
133 bool Done = ProcessInterval(getSourceGraphNode(OrigContainer, *SuccIt));
134 ++SuccIt; // Increment iterator
135 if (Done) return *this; // Found a new interval! Use it!
138 // Free interval memory... if neccesary
139 if (IOwnMem) delete IntStack.top().first;
141 // We ran out of successors for this interval... pop off the stack
143 } while (!IntStack.empty());
147 inline _Self operator++(int) { // Postincrement
148 _Self tmp = *this; ++*this; return tmp;
152 // ProcessInterval - This method is used during the construction of the
153 // interval graph. It walks through the source graph, recursively creating
154 // an interval per invokation until the entire graph is covered. This uses
155 // the ProcessNode method to add all of the nodes to the interval.
157 // This method is templated because it may operate on two different source
158 // graphs: a basic block graph, or a preexisting interval graph.
160 bool ProcessInterval(NodeTy *Node) {
161 BasicBlock *Header = getNodeHeader(Node);
162 if (Visited.count(Header)) return false;
164 Interval *Int = new Interval(Header);
165 Visited.insert(Header); // The header has now been visited!
167 // Check all of our successors to see if they are in the interval...
168 for (typename NodeTy::succ_iterator I = succ_begin(Node),
169 E = succ_end(Node); I != E; ++I)
170 ProcessNode(Int, getSourceGraphNode(OrigContainer, *I));
172 IntStack.push(make_pair(Int, succ_begin(Int)));
176 // ProcessNode - This method is called by ProcessInterval to add nodes to the
177 // interval being constructed, and it is also called recursively as it walks
178 // the source graph. A node is added to the current interval only if all of
179 // its predecessors are already in the graph. This also takes care of keeping
180 // the successor set of an interval up to date.
182 // This method is templated because it may operate on two different source
183 // graphs: a basic block graph, or a preexisting interval graph.
185 void ProcessNode(Interval *Int, NodeTy *Node) {
186 assert(Int && "Null interval == bad!");
187 assert(Node && "Null Node == bad!");
189 BasicBlock *NodeHeader = getNodeHeader(Node);
191 if (Visited.count(NodeHeader)) { // Node already been visited?
192 if (Int->contains(NodeHeader)) { // Already in this interval...
194 } else { // In other interval, add as successor
195 if (!Int->isSuccessor(NodeHeader)) // Add only if not already in set
196 Int->Successors.push_back(NodeHeader);
198 } else { // Otherwise, not in interval yet
199 for (typename NodeTy::pred_iterator I = pred_begin(Node),
200 E = pred_end(Node); I != E; ++I) {
201 if (!Int->contains(*I)) { // If pred not in interval, we can't be
202 if (!Int->isSuccessor(NodeHeader)) // Add only if not already in set
203 Int->Successors.push_back(NodeHeader);
204 return; // See you later
208 // If we get here, then all of the predecessors of BB are in the interval
209 // already. In this case, we must add BB to the interval!
210 addNodeToInterval(Int, Node);
211 Visited.insert(NodeHeader); // The node has now been visited!
213 if (Int->isSuccessor(NodeHeader)) {
214 // If we were in the successor list from before... remove from succ list
215 Int->Successors.erase(remove(Int->Successors.begin(),
216 Int->Successors.end(), NodeHeader),
217 Int->Successors.end());
220 // Now that we have discovered that Node is in the interval, perhaps some
221 // of its successors are as well?
222 for (typename NodeTy::succ_iterator It = succ_begin(Node),
223 End = succ_end(Node); It != End; ++It)
224 ProcessNode(Int, getSourceGraphNode(OrigContainer, *It));
229 typedef IntervalIterator<BasicBlock, Function> function_interval_iterator;
230 typedef IntervalIterator<Interval, IntervalPartition> interval_part_interval_iterator;
233 inline function_interval_iterator intervals_begin(Function *F,
234 bool DeleteInts = true) {
235 return function_interval_iterator(F, DeleteInts);
237 inline function_interval_iterator intervals_end(Function *) {
238 return function_interval_iterator();
241 inline interval_part_interval_iterator
242 intervals_begin(IntervalPartition &IP, bool DeleteIntervals = true) {
243 return interval_part_interval_iterator(IP, DeleteIntervals);
246 inline interval_part_interval_iterator intervals_end(IntervalPartition &IP) {
247 return interval_part_interval_iterator();