1 //===- IntervalIterator.h - Interval Iterator Declaration -------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 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: 13 // 14 // 1. A Function* object, composed of BasicBlock nodes. 15 // 2. An IntervalPartition& object, composed of Interval nodes. 16 // 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). 20 // 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. 25 // 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. 30 // 31 //===----------------------------------------------------------------------===// 32 33 #ifndef LLVM_ANALYSIS_INTERVALITERATOR_H 34 #define LLVM_ANALYSIS_INTERVALITERATOR_H 35 36 #include "llvm/Analysis/IntervalPartition.h" 37 #include "llvm/IR/CFG.h" 38 #include "llvm/IR/Function.h" 39 #include <algorithm> 40 #include <set> 41 #include <vector> 42 43 namespace llvm { 44 45 // getNodeHeader - Given a source graph node and the source graph, return the 46 // BasicBlock that is the header node. This is the opposite of 47 // getSourceGraphNode. 48 // 49 inline BasicBlock *getNodeHeader(BasicBlock *BB) { return BB; } 50 inline BasicBlock *getNodeHeader(Interval *I) { return I->getHeaderNode(); } 51 52 // getSourceGraphNode - Given a BasicBlock and the source graph, return the 53 // source graph node that corresponds to the BasicBlock. This is the opposite 54 // of getNodeHeader. 55 // 56 inline BasicBlock *getSourceGraphNode(Function *, BasicBlock *BB) { 57 return BB; 58 } 59 inline Interval *getSourceGraphNode(IntervalPartition *IP, BasicBlock *BB) { 60 return IP->getBlockInterval(BB); 61 } 62 63 // addNodeToInterval - This method exists to assist the generic ProcessNode 64 // with the task of adding a node to the new interval, depending on the 65 // type of the source node. In the case of a CFG source graph (BasicBlock 66 // case), the BasicBlock itself is added to the interval. 67 // 68 inline void addNodeToInterval(Interval *Int, BasicBlock *BB) { 69 Int->Nodes.push_back(BB); 70 } 71 72 // addNodeToInterval - This method exists to assist the generic ProcessNode 73 // with the task of adding a node to the new interval, depending on the 74 // type of the source node. In the case of a CFG source graph (BasicBlock 75 // case), the BasicBlock itself is added to the interval. In the case of 76 // an IntervalPartition source graph (Interval case), all of the member 77 // BasicBlocks are added to the interval. 78 // 79 inline void addNodeToInterval(Interval *Int, Interval *I) { 80 // Add all of the nodes in I as new nodes in Int. 81 Int->Nodes.insert(Int->Nodes.end(), I->Nodes.begin(), I->Nodes.end()); 82 } 83 84 85 86 87 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 96 public: 97 typedef std::forward_iterator_tag iterator_category; 98 99 IntervalIterator() {} // End iterator, empty stack 100 IntervalIterator(Function *M, bool OwnMemory) : IOwnMem(OwnMemory) { 101 OrigContainer = M; 102 if (!ProcessInterval(&M->front())) { 103 llvm_unreachable("ProcessInterval should never fail for first interval!"); 104 } 105 } 106 107 IntervalIterator(IntervalIterator &&x) 108 : IntStack(std::move(x.IntStack)), Visited(std::move(x.Visited)), 109 OrigContainer(x.OrigContainer), IOwnMem(x.IOwnMem) { 110 x.IOwnMem = false; 111 } 112 113 IntervalIterator(IntervalPartition &IP, bool OwnMemory) : IOwnMem(OwnMemory) { 114 OrigContainer = &IP; 115 if (!ProcessInterval(IP.getRootInterval())) { 116 llvm_unreachable("ProcessInterval should never fail for first interval!"); 117 } 118 } 119 120 ~IntervalIterator() { 121 if (IOwnMem) 122 while (!IntStack.empty()) { 123 delete operator*(); 124 IntStack.pop_back(); 125 } 126 } 127 128 bool operator==(const IntervalIterator &x) const { 129 return IntStack == x.IntStack; 130 } 131 bool operator!=(const IntervalIterator &x) const { return !(*this == x); } 132 133 const Interval *operator*() const { return IntStack.back().first; } 134 Interval *operator*() { return IntStack.back().first; } 135 const Interval *operator->() const { return operator*(); } 136 Interval *operator->() { return operator*(); } 137 138 IntervalIterator &operator++() { // Preincrement 139 assert(!IntStack.empty() && "Attempting to use interval iterator at end!"); 140 do { 141 // All of the intervals on the stack have been visited. Try visiting 142 // their successors now. 143 Interval::succ_iterator &SuccIt = IntStack.back().second, 144 EndIt = succ_end(IntStack.back().first); 145 while (SuccIt != EndIt) { // Loop over all interval succs 146 bool Done = ProcessInterval(getSourceGraphNode(OrigContainer, *SuccIt)); 147 ++SuccIt; // Increment iterator 148 if (Done) return *this; // Found a new interval! Use it! 149 } 150 151 // Free interval memory... if necessary 152 if (IOwnMem) delete IntStack.back().first; 153 154 // We ran out of successors for this interval... pop off the stack 155 IntStack.pop_back(); 156 } while (!IntStack.empty()); 157 158 return *this; 159 } 160 IntervalIterator operator++(int) { // Postincrement 161 IntervalIterator tmp = *this; 162 ++*this; 163 return tmp; 164 } 165 166 private: 167 // ProcessInterval - This method is used during the construction of the 168 // interval graph. It walks through the source graph, recursively creating 169 // an interval per invocation until the entire graph is covered. This uses 170 // the ProcessNode method to add all of the nodes to the interval. 171 // 172 // This method is templated because it may operate on two different source 173 // graphs: a basic block graph, or a preexisting interval graph. 174 // 175 bool ProcessInterval(NodeTy *Node) { 176 BasicBlock *Header = getNodeHeader(Node); 177 if (!Visited.insert(Header).second) 178 return false; 179 180 Interval *Int = new Interval(Header); 181 182 // Check all of our successors to see if they are in the interval... 183 for (typename GT::ChildIteratorType I = GT::child_begin(Node), 184 E = GT::child_end(Node); I != E; ++I) 185 ProcessNode(Int, getSourceGraphNode(OrigContainer, *I)); 186 187 IntStack.push_back(std::make_pair(Int, succ_begin(Int))); 188 return true; 189 } 190 191 // ProcessNode - This method is called by ProcessInterval to add nodes to the 192 // interval being constructed, and it is also called recursively as it walks 193 // the source graph. A node is added to the current interval only if all of 194 // its predecessors are already in the graph. This also takes care of keeping 195 // the successor set of an interval up to date. 196 // 197 // This method is templated because it may operate on two different source 198 // graphs: a basic block graph, or a preexisting interval graph. 199 // 200 void ProcessNode(Interval *Int, NodeTy *Node) { 201 assert(Int && "Null interval == bad!"); 202 assert(Node && "Null Node == bad!"); 203 204 BasicBlock *NodeHeader = getNodeHeader(Node); 205 206 if (Visited.count(NodeHeader)) { // Node already been visited? 207 if (Int->contains(NodeHeader)) { // Already in this interval... 208 return; 209 } else { // In other interval, add as successor 210 if (!Int->isSuccessor(NodeHeader)) // Add only if not already in set 211 Int->Successors.push_back(NodeHeader); 212 } 213 } else { // Otherwise, not in interval yet 214 for (typename IGT::ChildIteratorType I = IGT::child_begin(Node), 215 E = IGT::child_end(Node); I != E; ++I) { 216 if (!Int->contains(*I)) { // If pred not in interval, we can't be 217 if (!Int->isSuccessor(NodeHeader)) // Add only if not already in set 218 Int->Successors.push_back(NodeHeader); 219 return; // See you later 220 } 221 } 222 223 // If we get here, then all of the predecessors of BB are in the interval 224 // already. In this case, we must add BB to the interval! 225 addNodeToInterval(Int, Node); 226 Visited.insert(NodeHeader); // The node has now been visited! 227 228 if (Int->isSuccessor(NodeHeader)) { 229 // If we were in the successor list from before... remove from succ list 230 Int->Successors.erase(std::remove(Int->Successors.begin(), 231 Int->Successors.end(), NodeHeader), 232 Int->Successors.end()); 233 } 234 235 // Now that we have discovered that Node is in the interval, perhaps some 236 // of its successors are as well? 237 for (typename GT::ChildIteratorType It = GT::child_begin(Node), 238 End = GT::child_end(Node); It != End; ++It) 239 ProcessNode(Int, getSourceGraphNode(OrigContainer, *It)); 240 } 241 } 242 }; 243 244 typedef IntervalIterator<BasicBlock, Function> function_interval_iterator; 245 typedef IntervalIterator<Interval, IntervalPartition> 246 interval_part_interval_iterator; 247 248 249 inline function_interval_iterator intervals_begin(Function *F, 250 bool DeleteInts = true) { 251 return function_interval_iterator(F, DeleteInts); 252 } 253 inline function_interval_iterator intervals_end(Function *) { 254 return function_interval_iterator(); 255 } 256 257 inline interval_part_interval_iterator 258 intervals_begin(IntervalPartition &IP, bool DeleteIntervals = true) { 259 return interval_part_interval_iterator(IP, DeleteIntervals); 260 } 261 262 inline interval_part_interval_iterator intervals_end(IntervalPartition &IP) { 263 return interval_part_interval_iterator(); 264 } 265 266 } // End llvm namespace 267 268 #endif 269