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/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" 42#include <algorithm> 43#include <cassert> 44#include <iterator> 45#include <set> 46#include <utility> 47#include <vector> 48 49namespace llvm { 50 51class BasicBlock; 52 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. 56inline BasicBlock *getNodeHeader(BasicBlock *BB) { return BB; } 57inline BasicBlock *getNodeHeader(Interval *I) { return I->getHeaderNode(); } 58 59// getSourceGraphNode - Given a BasicBlock and the source graph, return the 60// source graph node that corresponds to the BasicBlock. This is the opposite 61// of getNodeHeader. 62inline BasicBlock *getSourceGraphNode(Function *, BasicBlock *BB) { 63 return BB; 64} 65inline Interval *getSourceGraphNode(IntervalPartition *IP, BasicBlock *BB) { 66 return IP->getBlockInterval(BB); 67} 68 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. 73inline void addNodeToInterval(Interval *Int, BasicBlock *BB) { 74 Int->Nodes.push_back(BB); 75} 76 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. 83inline 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()); 86} 87 88template<class NodeTy, class OrigContainer_t, class GT = GraphTraits<NodeTy *>, 89 class IGT = GraphTraits<Inverse<NodeTy *>>> 90class 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 97public: 98 using iterator_category = std::forward_iterator_tag; 99 100 IntervalIterator() = default; // End iterator, empty stack 101 102 IntervalIterator(Function *M, bool OwnMemory) : IOwnMem(OwnMemory) { 103 OrigContainer = M; 104 if (!ProcessInterval(&M->front())) { 105 llvm_unreachable("ProcessInterval should never fail for first interval!"); 106 } 107 } 108 109 IntervalIterator(IntervalIterator &&x) 110 : IntStack(std::move(x.IntStack)), Visited(std::move(x.Visited)), 111 OrigContainer(x.OrigContainer), IOwnMem(x.IOwnMem) { 112 x.IOwnMem = false; 113 } 114 115 IntervalIterator(IntervalPartition &IP, bool OwnMemory) : IOwnMem(OwnMemory) { 116 OrigContainer = &IP; 117 if (!ProcessInterval(IP.getRootInterval())) { 118 llvm_unreachable("ProcessInterval should never fail for first interval!"); 119 } 120 } 121 122 ~IntervalIterator() { 123 if (IOwnMem) 124 while (!IntStack.empty()) { 125 delete operator*(); 126 IntStack.pop_back(); 127 } 128 } 129 130 bool operator==(const IntervalIterator &x) const { 131 return IntStack == x.IntStack; 132 } 133 bool operator!=(const IntervalIterator &x) const { return !(*this == x); } 134 135 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*(); } 139 140 IntervalIterator &operator++() { // Preincrement 141 assert(!IntStack.empty() && "Attempting to use interval iterator at end!"); 142 do { 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! 151 } 152 153 // Free interval memory... if necessary 154 if (IOwnMem) delete IntStack.back().first; 155 156 // We ran out of successors for this interval... pop off the stack 157 IntStack.pop_back(); 158 } while (!IntStack.empty()); 159 160 return *this; 161 } 162 163 IntervalIterator operator++(int) { // Postincrement 164 IntervalIterator tmp = *this; 165 ++*this; 166 return tmp; 167 } 168 169private: 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. 174 // 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) 180 return false; 181 182 Interval *Int = new Interval(Header); 183 184 // 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)); 188 189 IntStack.push_back(std::make_pair(Int, succ_begin(Int))); 190 return true; 191 } 192 193 // 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. 198 // 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!"); 204 205 BasicBlock *NodeHeader = getNodeHeader(Node); 206 207 if (Visited.count(NodeHeader)) { // Node already been visited? 208 if (Int->contains(NodeHeader)) { // Already in this interval... 209 return; 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); 213 } 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 221 } 222 } 223 224 // 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! 228 229 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()); 234 } 235 236 // 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)); 241 } 242 } 243}; 244 245using function_interval_iterator = IntervalIterator<BasicBlock, Function>; 246using interval_part_interval_iterator = 247 IntervalIterator<Interval, IntervalPartition>; 248 249inline function_interval_iterator intervals_begin(Function *F, 250 bool DeleteInts = true) { 251 return function_interval_iterator(F, DeleteInts); 252} 253inline function_interval_iterator intervals_end(Function *) { 254 return function_interval_iterator(); 255} 256 257inline interval_part_interval_iterator 258 intervals_begin(IntervalPartition &IP, bool DeleteIntervals = true) { 259 return interval_part_interval_iterator(IP, DeleteIntervals); 260} 261 262inline interval_part_interval_iterator intervals_end(IntervalPartition &IP) { 263 return interval_part_interval_iterator(); 264} 265 266} // end namespace llvm 267 268#endif // LLVM_ANALYSIS_INTERVALITERATOR_H 269