LoopInfo.h revision f6c166078f8f10006dcbdde081603eccccfcefbe
17c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman//===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator -------*- C++ -*-===// 27c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman// 37c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman// The LLVM Compiler Infrastructure 47c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman// 57c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman// This file is distributed under the University of Illinois Open Source 67c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman// License. See LICENSE.TXT for details. 77c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman// 87c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman//===----------------------------------------------------------------------===// 97c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman// 107c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman// This file defines the LoopInfo class that is used to identify natural loops 11a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain// and determine the loop depth of various nodes of the CFG. A natural loop 12a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain// has exactly one entry-point, which is called the header. Note that natural 13a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain// loops may actually be several loops that share the same header node. 14a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain// 15a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain// This analysis calculates the nesting structure of loops in a function. For 16a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain// each natural loop identified, this analysis identifies natural loops 17a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain// contained entirely within the loop and the basic blocks the make up the loop. 18a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain// 19a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain// It can calculate on the fly various bits of information, for example: 20a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain// 217c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman// * whether there is a preheader for the loop 227c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman// * the number of back edges to the header 237c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman// * whether or not a particular block branches out of the loop 247c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman// * the successor blocks of the loop 25efac8e0abf13f9d69304c46d73d431b95c6b7a5cEd Maste// * the loop depth 268f3b21daa0d509ac49b2b82f45aaed35f6874502Greg Clayton// * the trip count 277c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman// * etc... 28444fe998bf707bd076a70c3a779db8575533695eGreg Clayton// 297c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman//===----------------------------------------------------------------------===// 308f3b21daa0d509ac49b2b82f45aaed35f6874502Greg Clayton 317c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman#ifndef LLVM_ANALYSIS_LOOP_INFO_H 327c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman#define LLVM_ANALYSIS_LOOP_INFO_H 337c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman 347c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman#include "llvm/Pass.h" 35444fe998bf707bd076a70c3a779db8575533695eGreg Clayton#include "llvm/ADT/DepthFirstIterator.h" 367c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman#include "llvm/ADT/GraphTraits.h" 37a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain#include "llvm/ADT/SmallVector.h" 38a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain#include "llvm/Analysis/Dominators.h" 39a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain#include "llvm/Support/CFG.h" 40a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain#include "llvm/Support/raw_ostream.h" 41a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain#include <algorithm> 42a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain 43a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartainnamespace llvm { 44a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain 45a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartaintemplate<typename T> 46a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartainstatic void RemoveFromVector(std::vector<T*> &V, T *N) { 47a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain typename std::vector<T*>::iterator I = std::find(V.begin(), V.end(), N); 48a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain assert(I != V.end() && "N is not in this list!"); 49a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain V.erase(I); 50a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain} 51a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain 52a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartainclass DominatorTree; 53a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartainclass LoopInfo; 54a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartainclass Loop; 55a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartaintemplate<class N, class M> class LoopInfoBase; 56a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartaintemplate<class N, class M> class LoopBase; 57a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain 58a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain//===----------------------------------------------------------------------===// 59a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain/// LoopBase class - Instances of this class are used to represent loops that 60a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain/// are detected in the flow graph 61a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain/// 62a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartaintemplate<class BlockT, class LoopT> 63a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartainclass LoopBase { 64a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain LoopT *ParentLoop; 65a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain // SubLoops - Loops contained entirely within this one. 66a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain std::vector<LoopT *> SubLoops; 67a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain 68a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain // Blocks - The list of blocks in this loop. First entry is the header node. 69a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain std::vector<BlockT*> Blocks; 70a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain 71a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain // DO NOT IMPLEMENT 72a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain LoopBase(const LoopBase<BlockT, LoopT> &); 73a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain // DO NOT IMPLEMENT 74a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain const LoopBase<BlockT, LoopT>&operator=(const LoopBase<BlockT, LoopT> &); 75a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartainpublic: 76a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain /// Loop ctor - This creates an empty loop. 77a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain LoopBase() : ParentLoop(0) {} 78a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain ~LoopBase() { 79a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain for (size_t i = 0, e = SubLoops.size(); i != e; ++i) 80a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain delete SubLoops[i]; 81a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain } 82a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain 83a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain /// getLoopDepth - Return the nesting level of this loop. An outer-most 84a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain /// loop has depth 1, for consistency with loop depth values used for basic 85a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain /// blocks, where depth 0 is used for blocks not inside any loops. 86a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain unsigned getLoopDepth() const { 87a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain unsigned D = 1; 88a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain for (const LoopT *CurLoop = ParentLoop; CurLoop; 89a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain CurLoop = CurLoop->ParentLoop) 90a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain ++D; 91a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain return D; 92a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain } 93a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain BlockT *getHeader() const { return Blocks.front(); } 94a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain LoopT *getParentLoop() const { return ParentLoop; } 95a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain 96f789be455cedca628d07b871831134198bbd686eGreg Clayton /// contains - Return true if the specified loop is contained within in 97a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain /// this loop. 98a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain /// 99a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain bool contains(const LoopT *L) const { 100a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain if (L == this) return true; 101a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain if (L == 0) return false; 102a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain return contains(L->getParentLoop()); 103a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain } 104a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain 105a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain /// contains - Return true if the specified basic block is in this loop. 106a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain /// 107a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain bool contains(const BlockT *BB) const { 108a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain return std::find(block_begin(), block_end(), BB) != block_end(); 109a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain } 110a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain 1117c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman /// contains - Return true if the specified instruction is in this loop. 1127c7c19d37de4ae8d455c18615fcce5691b236831Eli Friedman /// 1138f3b21daa0d509ac49b2b82f45aaed35f6874502Greg Clayton template<class InstT> 11495b765e8000b44644d021e95bc58eac95028573bGreg Clayton bool contains(const InstT *Inst) const { 11595b765e8000b44644d021e95bc58eac95028573bGreg Clayton return contains(Inst->getParent()); 11695b765e8000b44644d021e95bc58eac95028573bGreg Clayton } 11795b765e8000b44644d021e95bc58eac95028573bGreg Clayton 11895b765e8000b44644d021e95bc58eac95028573bGreg Clayton /// iterator/begin/end - Return the loops contained entirely within this loop. 119a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain /// 12095b765e8000b44644d021e95bc58eac95028573bGreg Clayton const std::vector<LoopT *> &getSubLoops() const { return SubLoops; } 12195b765e8000b44644d021e95bc58eac95028573bGreg Clayton typedef typename std::vector<LoopT *>::const_iterator iterator; 12295b765e8000b44644d021e95bc58eac95028573bGreg Clayton iterator begin() const { return SubLoops.begin(); } 123b924eb6c5250a9909dc55ac736d231f7ccae423bGreg Clayton iterator end() const { return SubLoops.end(); } 124ff0672484da1c1bcd51af22f609c888c40decb91Jason Molenda bool empty() const { return SubLoops.empty(); } 125b924eb6c5250a9909dc55ac736d231f7ccae423bGreg Clayton 126b924eb6c5250a9909dc55ac736d231f7ccae423bGreg Clayton /// getBlocks - Get a list of the basic blocks which make up this loop. 127b924eb6c5250a9909dc55ac736d231f7ccae423bGreg Clayton /// 128b924eb6c5250a9909dc55ac736d231f7ccae423bGreg Clayton const std::vector<BlockT*> &getBlocks() const { return Blocks; } 129b924eb6c5250a9909dc55ac736d231f7ccae423bGreg Clayton typedef typename std::vector<BlockT*>::const_iterator block_iterator; 130b924eb6c5250a9909dc55ac736d231f7ccae423bGreg Clayton block_iterator block_begin() const { return Blocks.begin(); } 131a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain block_iterator block_end() const { return Blocks.end(); } 132a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain 133a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain /// isLoopExiting - True if terminator in the block can branch to another 134a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain /// block that is outside of the current loop. 135a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain /// 136a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain bool isLoopExiting(const BlockT *BB) const { 137a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain typedef GraphTraits<BlockT*> BlockTraits; 138a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain for (typename BlockTraits::ChildIteratorType SI = 139a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain BlockTraits::child_begin(const_cast<BlockT*>(BB)), 140a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain SE = BlockTraits::child_end(const_cast<BlockT*>(BB)); SI != SE; ++SI) { 141a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain if (!contains(*SI)) 142a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain return true; 143a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain } 144a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain return false; 145a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain } 146a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain 147a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain /// getNumBackEdges - Calculate the number of back edges to the loop header 148a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain /// 149a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain unsigned getNumBackEdges() const { 150a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain unsigned NumBackEdges = 0; 151a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain BlockT *H = getHeader(); 152a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain 153a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits; 154a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain for (typename InvBlockTraits::ChildIteratorType I = 155a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain InvBlockTraits::child_begin(const_cast<BlockT*>(H)), 156a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain E = InvBlockTraits::child_end(const_cast<BlockT*>(H)); I != E; ++I) 157a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain if (contains(*I)) 158a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain ++NumBackEdges; 159a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain 160a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain return NumBackEdges; 161a807ceef5dad2b24e5bae5c5a193ff03aa7ec8d9Michael Sartain } 16295b765e8000b44644d021e95bc58eac95028573bGreg Clayton 1638f3b21daa0d509ac49b2b82f45aaed35f6874502Greg Clayton //===--------------------------------------------------------------------===// 164 // APIs for simple analysis of the loop. 165 // 166 // Note that all of these methods can fail on general loops (ie, there may not 167 // be a preheader, etc). For best success, the loop simplification and 168 // induction variable canonicalization pass should be used to normalize loops 169 // for easy analysis. These methods assume canonical loops. 170 171 /// getExitingBlocks - Return all blocks inside the loop that have successors 172 /// outside of the loop. These are the blocks _inside of the current loop_ 173 /// which branch out. The returned list is always unique. 174 /// 175 void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const { 176 // Sort the blocks vector so that we can use binary search to do quick 177 // lookups. 178 SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end()); 179 std::sort(LoopBBs.begin(), LoopBBs.end()); 180 181 typedef GraphTraits<BlockT*> BlockTraits; 182 for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI) 183 for (typename BlockTraits::ChildIteratorType I = 184 BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI); 185 I != E; ++I) 186 if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I)) { 187 // Not in current loop? It must be an exit block. 188 ExitingBlocks.push_back(*BI); 189 break; 190 } 191 } 192 193 /// getExitingBlock - If getExitingBlocks would return exactly one block, 194 /// return that block. Otherwise return null. 195 BlockT *getExitingBlock() const { 196 SmallVector<BlockT*, 8> ExitingBlocks; 197 getExitingBlocks(ExitingBlocks); 198 if (ExitingBlocks.size() == 1) 199 return ExitingBlocks[0]; 200 return 0; 201 } 202 203 /// getExitBlocks - Return all of the successor blocks of this loop. These 204 /// are the blocks _outside of the current loop_ which are branched to. 205 /// 206 void getExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const { 207 // Sort the blocks vector so that we can use binary search to do quick 208 // lookups. 209 SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end()); 210 std::sort(LoopBBs.begin(), LoopBBs.end()); 211 212 typedef GraphTraits<BlockT*> BlockTraits; 213 for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI) 214 for (typename BlockTraits::ChildIteratorType I = 215 BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI); 216 I != E; ++I) 217 if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I)) 218 // Not in current loop? It must be an exit block. 219 ExitBlocks.push_back(*I); 220 } 221 222 /// getExitBlock - If getExitBlocks would return exactly one block, 223 /// return that block. Otherwise return null. 224 BlockT *getExitBlock() const { 225 SmallVector<BlockT*, 8> ExitBlocks; 226 getExitBlocks(ExitBlocks); 227 if (ExitBlocks.size() == 1) 228 return ExitBlocks[0]; 229 return 0; 230 } 231 232 /// getExitEdges - Return all pairs of (_inside_block_,_outside_block_). 233 typedef std::pair<const BlockT*,const BlockT*> Edge; 234 void getExitEdges(SmallVectorImpl<Edge> &ExitEdges) const { 235 // Sort the blocks vector so that we can use binary search to do quick 236 // lookups. 237 SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end()); 238 std::sort(LoopBBs.begin(), LoopBBs.end()); 239 240 typedef GraphTraits<BlockT*> BlockTraits; 241 for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI) 242 for (typename BlockTraits::ChildIteratorType I = 243 BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI); 244 I != E; ++I) 245 if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I)) 246 // Not in current loop? It must be an exit block. 247 ExitEdges.push_back(std::make_pair(*BI, *I)); 248 } 249 250 /// getLoopPreheader - If there is a preheader for this loop, return it. A 251 /// loop has a preheader if there is only one edge to the header of the loop 252 /// from outside of the loop. If this is the case, the block branching to the 253 /// header of the loop is the preheader node. 254 /// 255 /// This method returns null if there is no preheader for the loop. 256 /// 257 BlockT *getLoopPreheader() const { 258 // Keep track of nodes outside the loop branching to the header... 259 BlockT *Out = getLoopPredecessor(); 260 if (!Out) return 0; 261 262 // Make sure there is only one exit out of the preheader. 263 typedef GraphTraits<BlockT*> BlockTraits; 264 typename BlockTraits::ChildIteratorType SI = BlockTraits::child_begin(Out); 265 ++SI; 266 if (SI != BlockTraits::child_end(Out)) 267 return 0; // Multiple exits from the block, must not be a preheader. 268 269 // The predecessor has exactly one successor, so it is a preheader. 270 return Out; 271 } 272 273 /// getLoopPredecessor - If the given loop's header has exactly one unique 274 /// predecessor outside the loop, return it. Otherwise return null. 275 /// This is less strict that the loop "preheader" concept, which requires 276 /// the predecessor to have exactly one successor. 277 /// 278 BlockT *getLoopPredecessor() const { 279 // Keep track of nodes outside the loop branching to the header... 280 BlockT *Out = 0; 281 282 // Loop over the predecessors of the header node... 283 BlockT *Header = getHeader(); 284 typedef GraphTraits<BlockT*> BlockTraits; 285 typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits; 286 for (typename InvBlockTraits::ChildIteratorType PI = 287 InvBlockTraits::child_begin(Header), 288 PE = InvBlockTraits::child_end(Header); PI != PE; ++PI) 289 if (!contains(*PI)) { // If the block is not in the loop... 290 if (Out && Out != *PI) 291 return 0; // Multiple predecessors outside the loop 292 Out = *PI; 293 } 294 295 // Make sure there is only one exit out of the preheader. 296 assert(Out && "Header of loop has no predecessors from outside loop?"); 297 return Out; 298 } 299 300 /// getLoopLatch - If there is a single latch block for this loop, return it. 301 /// A latch block is a block that contains a branch back to the header. 302 BlockT *getLoopLatch() const { 303 BlockT *Header = getHeader(); 304 typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits; 305 typename InvBlockTraits::ChildIteratorType PI = 306 InvBlockTraits::child_begin(Header); 307 typename InvBlockTraits::ChildIteratorType PE = 308 InvBlockTraits::child_end(Header); 309 BlockT *Latch = 0; 310 for (; PI != PE; ++PI) 311 if (contains(*PI)) { 312 if (Latch) return 0; 313 Latch = *PI; 314 } 315 316 return Latch; 317 } 318 319 //===--------------------------------------------------------------------===// 320 // APIs for updating loop information after changing the CFG 321 // 322 323 /// addBasicBlockToLoop - This method is used by other analyses to update loop 324 /// information. NewBB is set to be a new member of the current loop. 325 /// Because of this, it is added as a member of all parent loops, and is added 326 /// to the specified LoopInfo object as being in the current basic block. It 327 /// is not valid to replace the loop header with this method. 328 /// 329 void addBasicBlockToLoop(BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &LI); 330 331 /// replaceChildLoopWith - This is used when splitting loops up. It replaces 332 /// the OldChild entry in our children list with NewChild, and updates the 333 /// parent pointer of OldChild to be null and the NewChild to be this loop. 334 /// This updates the loop depth of the new child. 335 void replaceChildLoopWith(LoopT *OldChild, 336 LoopT *NewChild) { 337 assert(OldChild->ParentLoop == this && "This loop is already broken!"); 338 assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!"); 339 typename std::vector<LoopT *>::iterator I = 340 std::find(SubLoops.begin(), SubLoops.end(), OldChild); 341 assert(I != SubLoops.end() && "OldChild not in loop!"); 342 *I = NewChild; 343 OldChild->ParentLoop = 0; 344 NewChild->ParentLoop = static_cast<LoopT *>(this); 345 } 346 347 /// addChildLoop - Add the specified loop to be a child of this loop. This 348 /// updates the loop depth of the new child. 349 /// 350 void addChildLoop(LoopT *NewChild) { 351 assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!"); 352 NewChild->ParentLoop = static_cast<LoopT *>(this); 353 SubLoops.push_back(NewChild); 354 } 355 356 /// removeChildLoop - This removes the specified child from being a subloop of 357 /// this loop. The loop is not deleted, as it will presumably be inserted 358 /// into another loop. 359 LoopT *removeChildLoop(iterator I) { 360 assert(I != SubLoops.end() && "Cannot remove end iterator!"); 361 LoopT *Child = *I; 362 assert(Child->ParentLoop == this && "Child is not a child of this loop!"); 363 SubLoops.erase(SubLoops.begin()+(I-begin())); 364 Child->ParentLoop = 0; 365 return Child; 366 } 367 368 /// addBlockEntry - This adds a basic block directly to the basic block list. 369 /// This should only be used by transformations that create new loops. Other 370 /// transformations should use addBasicBlockToLoop. 371 void addBlockEntry(BlockT *BB) { 372 Blocks.push_back(BB); 373 } 374 375 /// moveToHeader - This method is used to move BB (which must be part of this 376 /// loop) to be the loop header of the loop (the block that dominates all 377 /// others). 378 void moveToHeader(BlockT *BB) { 379 if (Blocks[0] == BB) return; 380 for (unsigned i = 0; ; ++i) { 381 assert(i != Blocks.size() && "Loop does not contain BB!"); 382 if (Blocks[i] == BB) { 383 Blocks[i] = Blocks[0]; 384 Blocks[0] = BB; 385 return; 386 } 387 } 388 } 389 390 /// removeBlockFromLoop - This removes the specified basic block from the 391 /// current loop, updating the Blocks as appropriate. This does not update 392 /// the mapping in the LoopInfo class. 393 void removeBlockFromLoop(BlockT *BB) { 394 RemoveFromVector(Blocks, BB); 395 } 396 397 /// verifyLoop - Verify loop structure 398 void verifyLoop() const { 399#ifndef NDEBUG 400 assert(!Blocks.empty() && "Loop header is missing"); 401 402 // Sort the blocks vector so that we can use binary search to do quick 403 // lookups. 404 SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end()); 405 std::sort(LoopBBs.begin(), LoopBBs.end()); 406 407 // Check the individual blocks. 408 for (block_iterator I = block_begin(), E = block_end(); I != E; ++I) { 409 BlockT *BB = *I; 410 bool HasInsideLoopSuccs = false; 411 bool HasInsideLoopPreds = false; 412 SmallVector<BlockT *, 2> OutsideLoopPreds; 413 414 typedef GraphTraits<BlockT*> BlockTraits; 415 for (typename BlockTraits::ChildIteratorType SI = 416 BlockTraits::child_begin(BB), SE = BlockTraits::child_end(BB); 417 SI != SE; ++SI) 418 if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), *SI)) { 419 HasInsideLoopSuccs = true; 420 break; 421 } 422 typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits; 423 for (typename InvBlockTraits::ChildIteratorType PI = 424 InvBlockTraits::child_begin(BB), PE = InvBlockTraits::child_end(BB); 425 PI != PE; ++PI) { 426 if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), *PI)) 427 HasInsideLoopPreds = true; 428 else 429 OutsideLoopPreds.push_back(*PI); 430 } 431 432 if (BB == getHeader()) { 433 assert(!OutsideLoopPreds.empty() && "Loop is unreachable!"); 434 } else if (!OutsideLoopPreds.empty()) { 435 // A non-header loop shouldn't be reachable from outside the loop, 436 // though it is permitted if the predecessor is not itself actually 437 // reachable. 438 BlockT *EntryBB = BB->getParent()->begin(); 439 for (df_iterator<BlockT *> NI = df_begin(EntryBB), 440 NE = df_end(EntryBB); NI != NE; ++NI) 441 for (unsigned i = 0, e = OutsideLoopPreds.size(); i != e; ++i) 442 assert(*NI != OutsideLoopPreds[i] && 443 "Loop has multiple entry points!"); 444 } 445 assert(HasInsideLoopPreds && "Loop block has no in-loop predecessors!"); 446 assert(HasInsideLoopSuccs && "Loop block has no in-loop successors!"); 447 assert(BB != getHeader()->getParent()->begin() && 448 "Loop contains function entry block!"); 449 } 450 451 // Check the subloops. 452 for (iterator I = begin(), E = end(); I != E; ++I) 453 // Each block in each subloop should be contained within this loop. 454 for (block_iterator BI = (*I)->block_begin(), BE = (*I)->block_end(); 455 BI != BE; ++BI) { 456 assert(std::binary_search(LoopBBs.begin(), LoopBBs.end(), *BI) && 457 "Loop does not contain all the blocks of a subloop!"); 458 } 459 460 // Check the parent loop pointer. 461 if (ParentLoop) { 462 assert(std::find(ParentLoop->begin(), ParentLoop->end(), this) != 463 ParentLoop->end() && 464 "Loop is not a subloop of its parent!"); 465 } 466#endif 467 } 468 469 /// verifyLoop - Verify loop structure of this loop and all nested loops. 470 void verifyLoopNest() const { 471 // Verify this loop. 472 verifyLoop(); 473 // Verify the subloops. 474 for (iterator I = begin(), E = end(); I != E; ++I) 475 (*I)->verifyLoopNest(); 476 } 477 478 void print(raw_ostream &OS, unsigned Depth = 0) const { 479 OS.indent(Depth*2) << "Loop at depth " << getLoopDepth() 480 << " containing: "; 481 482 for (unsigned i = 0; i < getBlocks().size(); ++i) { 483 if (i) OS << ","; 484 BlockT *BB = getBlocks()[i]; 485 WriteAsOperand(OS, BB, false); 486 if (BB == getHeader()) OS << "<header>"; 487 if (BB == getLoopLatch()) OS << "<latch>"; 488 if (isLoopExiting(BB)) OS << "<exiting>"; 489 } 490 OS << "\n"; 491 492 for (iterator I = begin(), E = end(); I != E; ++I) 493 (*I)->print(OS, Depth+2); 494 } 495 496protected: 497 friend class LoopInfoBase<BlockT, LoopT>; 498 explicit LoopBase(BlockT *BB) : ParentLoop(0) { 499 Blocks.push_back(BB); 500 } 501}; 502 503class Loop : public LoopBase<BasicBlock, Loop> { 504public: 505 Loop() {} 506 507 /// isLoopInvariant - Return true if the specified value is loop invariant 508 /// 509 bool isLoopInvariant(Value *V) const; 510 511 /// isLoopInvariant - Return true if the specified instruction is 512 /// loop-invariant. 513 /// 514 bool isLoopInvariant(Instruction *I) const; 515 516 /// makeLoopInvariant - If the given value is an instruction inside of the 517 /// loop and it can be hoisted, do so to make it trivially loop-invariant. 518 /// Return true if the value after any hoisting is loop invariant. This 519 /// function can be used as a slightly more aggressive replacement for 520 /// isLoopInvariant. 521 /// 522 /// If InsertPt is specified, it is the point to hoist instructions to. 523 /// If null, the terminator of the loop preheader is used. 524 /// 525 bool makeLoopInvariant(Value *V, bool &Changed, 526 Instruction *InsertPt = 0) const; 527 528 /// makeLoopInvariant - If the given instruction is inside of the 529 /// loop and it can be hoisted, do so to make it trivially loop-invariant. 530 /// Return true if the instruction after any hoisting is loop invariant. This 531 /// function can be used as a slightly more aggressive replacement for 532 /// isLoopInvariant. 533 /// 534 /// If InsertPt is specified, it is the point to hoist instructions to. 535 /// If null, the terminator of the loop preheader is used. 536 /// 537 bool makeLoopInvariant(Instruction *I, bool &Changed, 538 Instruction *InsertPt = 0) const; 539 540 /// getCanonicalInductionVariable - Check to see if the loop has a canonical 541 /// induction variable: an integer recurrence that starts at 0 and increments 542 /// by one each time through the loop. If so, return the phi node that 543 /// corresponds to it. 544 /// 545 /// The IndVarSimplify pass transforms loops to have a canonical induction 546 /// variable. 547 /// 548 PHINode *getCanonicalInductionVariable() const; 549 550 /// getCanonicalInductionVariableIncrement - Return the LLVM value that holds 551 /// the canonical induction variable value for the "next" iteration of the 552 /// loop. This always succeeds if getCanonicalInductionVariable succeeds. 553 /// 554 Instruction *getCanonicalInductionVariableIncrement() const; 555 556 /// getTripCount - Return a loop-invariant LLVM value indicating the number of 557 /// times the loop will be executed. Note that this means that the backedge 558 /// of the loop executes N-1 times. If the trip-count cannot be determined, 559 /// this returns null. 560 /// 561 /// The IndVarSimplify pass transforms loops to have a form that this 562 /// function easily understands. 563 /// 564 Value *getTripCount() const; 565 566 /// getSmallConstantTripCount - Returns the trip count of this loop as a 567 /// normal unsigned value, if possible. Returns 0 if the trip count is unknown 568 /// of not constant. Will also return 0 if the trip count is very large 569 /// (>= 2^32) 570 /// 571 /// The IndVarSimplify pass transforms loops to have a form that this 572 /// function easily understands. 573 /// 574 unsigned getSmallConstantTripCount() const; 575 576 /// getSmallConstantTripMultiple - Returns the largest constant divisor of the 577 /// trip count of this loop as a normal unsigned value, if possible. This 578 /// means that the actual trip count is always a multiple of the returned 579 /// value (don't forget the trip count could very well be zero as well!). 580 /// 581 /// Returns 1 if the trip count is unknown or not guaranteed to be the 582 /// multiple of a constant (which is also the case if the trip count is simply 583 /// constant, use getSmallConstantTripCount for that case), Will also return 1 584 /// if the trip count is very large (>= 2^32). 585 unsigned getSmallConstantTripMultiple() const; 586 587 /// isLCSSAForm - Return true if the Loop is in LCSSA form 588 bool isLCSSAForm(DominatorTree &DT) const; 589 590 /// isLoopSimplifyForm - Return true if the Loop is in the form that 591 /// the LoopSimplify form transforms loops to, which is sometimes called 592 /// normal form. 593 bool isLoopSimplifyForm() const; 594 595 /// hasDedicatedExits - Return true if no exit block for the loop 596 /// has a predecessor that is outside the loop. 597 bool hasDedicatedExits() const; 598 599 /// getUniqueExitBlocks - Return all unique successor blocks of this loop. 600 /// These are the blocks _outside of the current loop_ which are branched to. 601 /// This assumes that loop exits are in canonical form. 602 /// 603 void getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const; 604 605 /// getUniqueExitBlock - If getUniqueExitBlocks would return exactly one 606 /// block, return that block. Otherwise return null. 607 BasicBlock *getUniqueExitBlock() const; 608 609 void dump() const; 610 611private: 612 friend class LoopInfoBase<BasicBlock, Loop>; 613 explicit Loop(BasicBlock *BB) : LoopBase<BasicBlock, Loop>(BB) {} 614}; 615 616//===----------------------------------------------------------------------===// 617/// LoopInfo - This class builds and contains all of the top level loop 618/// structures in the specified function. 619/// 620 621template<class BlockT, class LoopT> 622class LoopInfoBase { 623 // BBMap - Mapping of basic blocks to the inner most loop they occur in 624 std::map<BlockT *, LoopT *> BBMap; 625 std::vector<LoopT *> TopLevelLoops; 626 friend class LoopBase<BlockT, LoopT>; 627 628 void operator=(const LoopInfoBase &); // do not implement 629 LoopInfoBase(const LoopInfo &); // do not implement 630public: 631 LoopInfoBase() { } 632 ~LoopInfoBase() { releaseMemory(); } 633 634 void releaseMemory() { 635 for (typename std::vector<LoopT *>::iterator I = 636 TopLevelLoops.begin(), E = TopLevelLoops.end(); I != E; ++I) 637 delete *I; // Delete all of the loops... 638 639 BBMap.clear(); // Reset internal state of analysis 640 TopLevelLoops.clear(); 641 } 642 643 /// iterator/begin/end - The interface to the top-level loops in the current 644 /// function. 645 /// 646 typedef typename std::vector<LoopT *>::const_iterator iterator; 647 iterator begin() const { return TopLevelLoops.begin(); } 648 iterator end() const { return TopLevelLoops.end(); } 649 bool empty() const { return TopLevelLoops.empty(); } 650 651 /// getLoopFor - Return the inner most loop that BB lives in. If a basic 652 /// block is in no loop (for example the entry node), null is returned. 653 /// 654 LoopT *getLoopFor(const BlockT *BB) const { 655 typename std::map<BlockT *, LoopT *>::const_iterator I= 656 BBMap.find(const_cast<BlockT*>(BB)); 657 return I != BBMap.end() ? I->second : 0; 658 } 659 660 /// operator[] - same as getLoopFor... 661 /// 662 const LoopT *operator[](const BlockT *BB) const { 663 return getLoopFor(BB); 664 } 665 666 /// getLoopDepth - Return the loop nesting level of the specified block. A 667 /// depth of 0 means the block is not inside any loop. 668 /// 669 unsigned getLoopDepth(const BlockT *BB) const { 670 const LoopT *L = getLoopFor(BB); 671 return L ? L->getLoopDepth() : 0; 672 } 673 674 // isLoopHeader - True if the block is a loop header node 675 bool isLoopHeader(BlockT *BB) const { 676 const LoopT *L = getLoopFor(BB); 677 return L && L->getHeader() == BB; 678 } 679 680 /// removeLoop - This removes the specified top-level loop from this loop info 681 /// object. The loop is not deleted, as it will presumably be inserted into 682 /// another loop. 683 LoopT *removeLoop(iterator I) { 684 assert(I != end() && "Cannot remove end iterator!"); 685 LoopT *L = *I; 686 assert(L->getParentLoop() == 0 && "Not a top-level loop!"); 687 TopLevelLoops.erase(TopLevelLoops.begin() + (I-begin())); 688 return L; 689 } 690 691 /// changeLoopFor - Change the top-level loop that contains BB to the 692 /// specified loop. This should be used by transformations that restructure 693 /// the loop hierarchy tree. 694 void changeLoopFor(BlockT *BB, LoopT *L) { 695 LoopT *&OldLoop = BBMap[BB]; 696 assert(OldLoop && "Block not in a loop yet!"); 697 OldLoop = L; 698 } 699 700 /// changeTopLevelLoop - Replace the specified loop in the top-level loops 701 /// list with the indicated loop. 702 void changeTopLevelLoop(LoopT *OldLoop, 703 LoopT *NewLoop) { 704 typename std::vector<LoopT *>::iterator I = 705 std::find(TopLevelLoops.begin(), TopLevelLoops.end(), OldLoop); 706 assert(I != TopLevelLoops.end() && "Old loop not at top level!"); 707 *I = NewLoop; 708 assert(NewLoop->ParentLoop == 0 && OldLoop->ParentLoop == 0 && 709 "Loops already embedded into a subloop!"); 710 } 711 712 /// addTopLevelLoop - This adds the specified loop to the collection of 713 /// top-level loops. 714 void addTopLevelLoop(LoopT *New) { 715 assert(New->getParentLoop() == 0 && "Loop already in subloop!"); 716 TopLevelLoops.push_back(New); 717 } 718 719 /// removeBlock - This method completely removes BB from all data structures, 720 /// including all of the Loop objects it is nested in and our mapping from 721 /// BasicBlocks to loops. 722 void removeBlock(BlockT *BB) { 723 typename std::map<BlockT *, LoopT *>::iterator I = BBMap.find(BB); 724 if (I != BBMap.end()) { 725 for (LoopT *L = I->second; L; L = L->getParentLoop()) 726 L->removeBlockFromLoop(BB); 727 728 BBMap.erase(I); 729 } 730 } 731 732 // Internals 733 734 static bool isNotAlreadyContainedIn(const LoopT *SubLoop, 735 const LoopT *ParentLoop) { 736 if (SubLoop == 0) return true; 737 if (SubLoop == ParentLoop) return false; 738 return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop); 739 } 740 741 void Calculate(DominatorTreeBase<BlockT> &DT) { 742 BlockT *RootNode = DT.getRootNode()->getBlock(); 743 744 for (df_iterator<BlockT*> NI = df_begin(RootNode), 745 NE = df_end(RootNode); NI != NE; ++NI) 746 if (LoopT *L = ConsiderForLoop(*NI, DT)) 747 TopLevelLoops.push_back(L); 748 } 749 750 LoopT *ConsiderForLoop(BlockT *BB, DominatorTreeBase<BlockT> &DT) { 751 if (BBMap.find(BB) != BBMap.end()) return 0;// Haven't processed this node? 752 753 std::vector<BlockT *> TodoStack; 754 755 // Scan the predecessors of BB, checking to see if BB dominates any of 756 // them. This identifies backedges which target this node... 757 typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits; 758 for (typename InvBlockTraits::ChildIteratorType I = 759 InvBlockTraits::child_begin(BB), E = InvBlockTraits::child_end(BB); 760 I != E; ++I) { 761 typename InvBlockTraits::NodeType *N = *I; 762 if (DT.dominates(BB, N)) // If BB dominates its predecessor... 763 TodoStack.push_back(N); 764 } 765 766 if (TodoStack.empty()) return 0; // No backedges to this block... 767 768 // Create a new loop to represent this basic block... 769 LoopT *L = new LoopT(BB); 770 BBMap[BB] = L; 771 772 BlockT *EntryBlock = BB->getParent()->begin(); 773 774 while (!TodoStack.empty()) { // Process all the nodes in the loop 775 BlockT *X = TodoStack.back(); 776 TodoStack.pop_back(); 777 778 if (!L->contains(X) && // As of yet unprocessed?? 779 DT.dominates(EntryBlock, X)) { // X is reachable from entry block? 780 // Check to see if this block already belongs to a loop. If this occurs 781 // then we have a case where a loop that is supposed to be a child of 782 // the current loop was processed before the current loop. When this 783 // occurs, this child loop gets added to a part of the current loop, 784 // making it a sibling to the current loop. We have to reparent this 785 // loop. 786 if (LoopT *SubLoop = 787 const_cast<LoopT *>(getLoopFor(X))) 788 if (SubLoop->getHeader() == X && isNotAlreadyContainedIn(SubLoop, L)){ 789 // Remove the subloop from its current parent... 790 assert(SubLoop->ParentLoop && SubLoop->ParentLoop != L); 791 LoopT *SLP = SubLoop->ParentLoop; // SubLoopParent 792 typename std::vector<LoopT *>::iterator I = 793 std::find(SLP->SubLoops.begin(), SLP->SubLoops.end(), SubLoop); 794 assert(I != SLP->SubLoops.end() &&"SubLoop not a child of parent?"); 795 SLP->SubLoops.erase(I); // Remove from parent... 796 797 // Add the subloop to THIS loop... 798 SubLoop->ParentLoop = L; 799 L->SubLoops.push_back(SubLoop); 800 } 801 802 // Normal case, add the block to our loop... 803 L->Blocks.push_back(X); 804 805 typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits; 806 807 // Add all of the predecessors of X to the end of the work stack... 808 TodoStack.insert(TodoStack.end(), InvBlockTraits::child_begin(X), 809 InvBlockTraits::child_end(X)); 810 } 811 } 812 813 // If there are any loops nested within this loop, create them now! 814 for (typename std::vector<BlockT*>::iterator I = L->Blocks.begin(), 815 E = L->Blocks.end(); I != E; ++I) 816 if (LoopT *NewLoop = ConsiderForLoop(*I, DT)) { 817 L->SubLoops.push_back(NewLoop); 818 NewLoop->ParentLoop = L; 819 } 820 821 // Add the basic blocks that comprise this loop to the BBMap so that this 822 // loop can be found for them. 823 // 824 for (typename std::vector<BlockT*>::iterator I = L->Blocks.begin(), 825 E = L->Blocks.end(); I != E; ++I) 826 BBMap.insert(std::make_pair(*I, L)); 827 828 // Now that we have a list of all of the child loops of this loop, check to 829 // see if any of them should actually be nested inside of each other. We 830 // can accidentally pull loops our of their parents, so we must make sure to 831 // organize the loop nests correctly now. 832 { 833 std::map<BlockT *, LoopT *> ContainingLoops; 834 for (unsigned i = 0; i != L->SubLoops.size(); ++i) { 835 LoopT *Child = L->SubLoops[i]; 836 assert(Child->getParentLoop() == L && "Not proper child loop?"); 837 838 if (LoopT *ContainingLoop = ContainingLoops[Child->getHeader()]) { 839 // If there is already a loop which contains this loop, move this loop 840 // into the containing loop. 841 MoveSiblingLoopInto(Child, ContainingLoop); 842 --i; // The loop got removed from the SubLoops list. 843 } else { 844 // This is currently considered to be a top-level loop. Check to see 845 // if any of the contained blocks are loop headers for subloops we 846 // have already processed. 847 for (unsigned b = 0, e = Child->Blocks.size(); b != e; ++b) { 848 LoopT *&BlockLoop = ContainingLoops[Child->Blocks[b]]; 849 if (BlockLoop == 0) { // Child block not processed yet... 850 BlockLoop = Child; 851 } else if (BlockLoop != Child) { 852 LoopT *SubLoop = BlockLoop; 853 // Reparent all of the blocks which used to belong to BlockLoops 854 for (unsigned j = 0, f = SubLoop->Blocks.size(); j != f; ++j) 855 ContainingLoops[SubLoop->Blocks[j]] = Child; 856 857 // There is already a loop which contains this block, that means 858 // that we should reparent the loop which the block is currently 859 // considered to belong to to be a child of this loop. 860 MoveSiblingLoopInto(SubLoop, Child); 861 --i; // We just shrunk the SubLoops list. 862 } 863 } 864 } 865 } 866 } 867 868 return L; 869 } 870 871 /// MoveSiblingLoopInto - This method moves the NewChild loop to live inside 872 /// of the NewParent Loop, instead of being a sibling of it. 873 void MoveSiblingLoopInto(LoopT *NewChild, 874 LoopT *NewParent) { 875 LoopT *OldParent = NewChild->getParentLoop(); 876 assert(OldParent && OldParent == NewParent->getParentLoop() && 877 NewChild != NewParent && "Not sibling loops!"); 878 879 // Remove NewChild from being a child of OldParent 880 typename std::vector<LoopT *>::iterator I = 881 std::find(OldParent->SubLoops.begin(), OldParent->SubLoops.end(), 882 NewChild); 883 assert(I != OldParent->SubLoops.end() && "Parent fields incorrect??"); 884 OldParent->SubLoops.erase(I); // Remove from parent's subloops list 885 NewChild->ParentLoop = 0; 886 887 InsertLoopInto(NewChild, NewParent); 888 } 889 890 /// InsertLoopInto - This inserts loop L into the specified parent loop. If 891 /// the parent loop contains a loop which should contain L, the loop gets 892 /// inserted into L instead. 893 void InsertLoopInto(LoopT *L, LoopT *Parent) { 894 BlockT *LHeader = L->getHeader(); 895 assert(Parent->contains(LHeader) && 896 "This loop should not be inserted here!"); 897 898 // Check to see if it belongs in a child loop... 899 for (unsigned i = 0, e = static_cast<unsigned>(Parent->SubLoops.size()); 900 i != e; ++i) 901 if (Parent->SubLoops[i]->contains(LHeader)) { 902 InsertLoopInto(L, Parent->SubLoops[i]); 903 return; 904 } 905 906 // If not, insert it here! 907 Parent->SubLoops.push_back(L); 908 L->ParentLoop = Parent; 909 } 910 911 // Debugging 912 913 void print(raw_ostream &OS) const { 914 for (unsigned i = 0; i < TopLevelLoops.size(); ++i) 915 TopLevelLoops[i]->print(OS); 916 #if 0 917 for (std::map<BasicBlock*, LoopT*>::const_iterator I = BBMap.begin(), 918 E = BBMap.end(); I != E; ++I) 919 OS << "BB '" << I->first->getName() << "' level = " 920 << I->second->getLoopDepth() << "\n"; 921 #endif 922 } 923}; 924 925class LoopInfo : public FunctionPass { 926 LoopInfoBase<BasicBlock, Loop> LI; 927 friend class LoopBase<BasicBlock, Loop>; 928 929 void operator=(const LoopInfo &); // do not implement 930 LoopInfo(const LoopInfo &); // do not implement 931public: 932 static char ID; // Pass identification, replacement for typeid 933 934 LoopInfo() : FunctionPass(&ID) {} 935 936 LoopInfoBase<BasicBlock, Loop>& getBase() { return LI; } 937 938 /// iterator/begin/end - The interface to the top-level loops in the current 939 /// function. 940 /// 941 typedef LoopInfoBase<BasicBlock, Loop>::iterator iterator; 942 inline iterator begin() const { return LI.begin(); } 943 inline iterator end() const { return LI.end(); } 944 bool empty() const { return LI.empty(); } 945 946 /// getLoopFor - Return the inner most loop that BB lives in. If a basic 947 /// block is in no loop (for example the entry node), null is returned. 948 /// 949 inline Loop *getLoopFor(const BasicBlock *BB) const { 950 return LI.getLoopFor(BB); 951 } 952 953 /// operator[] - same as getLoopFor... 954 /// 955 inline const Loop *operator[](const BasicBlock *BB) const { 956 return LI.getLoopFor(BB); 957 } 958 959 /// getLoopDepth - Return the loop nesting level of the specified block. A 960 /// depth of 0 means the block is not inside any loop. 961 /// 962 inline unsigned getLoopDepth(const BasicBlock *BB) const { 963 return LI.getLoopDepth(BB); 964 } 965 966 // isLoopHeader - True if the block is a loop header node 967 inline bool isLoopHeader(BasicBlock *BB) const { 968 return LI.isLoopHeader(BB); 969 } 970 971 /// runOnFunction - Calculate the natural loop information. 972 /// 973 virtual bool runOnFunction(Function &F); 974 975 virtual void verifyAnalysis() const; 976 977 virtual void releaseMemory() { LI.releaseMemory(); } 978 979 virtual void print(raw_ostream &O, const Module* M = 0) const; 980 981 virtual void getAnalysisUsage(AnalysisUsage &AU) const; 982 983 /// removeLoop - This removes the specified top-level loop from this loop info 984 /// object. The loop is not deleted, as it will presumably be inserted into 985 /// another loop. 986 inline Loop *removeLoop(iterator I) { return LI.removeLoop(I); } 987 988 /// changeLoopFor - Change the top-level loop that contains BB to the 989 /// specified loop. This should be used by transformations that restructure 990 /// the loop hierarchy tree. 991 inline void changeLoopFor(BasicBlock *BB, Loop *L) { 992 LI.changeLoopFor(BB, L); 993 } 994 995 /// changeTopLevelLoop - Replace the specified loop in the top-level loops 996 /// list with the indicated loop. 997 inline void changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop) { 998 LI.changeTopLevelLoop(OldLoop, NewLoop); 999 } 1000 1001 /// addTopLevelLoop - This adds the specified loop to the collection of 1002 /// top-level loops. 1003 inline void addTopLevelLoop(Loop *New) { 1004 LI.addTopLevelLoop(New); 1005 } 1006 1007 /// removeBlock - This method completely removes BB from all data structures, 1008 /// including all of the Loop objects it is nested in and our mapping from 1009 /// BasicBlocks to loops. 1010 void removeBlock(BasicBlock *BB) { 1011 LI.removeBlock(BB); 1012 } 1013}; 1014 1015 1016// Allow clients to walk the list of nested loops... 1017template <> struct GraphTraits<const Loop*> { 1018 typedef const Loop NodeType; 1019 typedef LoopInfo::iterator ChildIteratorType; 1020 1021 static NodeType *getEntryNode(const Loop *L) { return L; } 1022 static inline ChildIteratorType child_begin(NodeType *N) { 1023 return N->begin(); 1024 } 1025 static inline ChildIteratorType child_end(NodeType *N) { 1026 return N->end(); 1027 } 1028}; 1029 1030template <> struct GraphTraits<Loop*> { 1031 typedef Loop NodeType; 1032 typedef LoopInfo::iterator ChildIteratorType; 1033 1034 static NodeType *getEntryNode(Loop *L) { return L; } 1035 static inline ChildIteratorType child_begin(NodeType *N) { 1036 return N->begin(); 1037 } 1038 static inline ChildIteratorType child_end(NodeType *N) { 1039 return N->end(); 1040 } 1041}; 1042 1043template<class BlockT, class LoopT> 1044void 1045LoopBase<BlockT, LoopT>::addBasicBlockToLoop(BlockT *NewBB, 1046 LoopInfoBase<BlockT, LoopT> &LIB) { 1047 assert((Blocks.empty() || LIB[getHeader()] == this) && 1048 "Incorrect LI specified for this loop!"); 1049 assert(NewBB && "Cannot add a null basic block to the loop!"); 1050 assert(LIB[NewBB] == 0 && "BasicBlock already in the loop!"); 1051 1052 LoopT *L = static_cast<LoopT *>(this); 1053 1054 // Add the loop mapping to the LoopInfo object... 1055 LIB.BBMap[NewBB] = L; 1056 1057 // Add the basic block to this loop and all parent loops... 1058 while (L) { 1059 L->Blocks.push_back(NewBB); 1060 L = L->getParentLoop(); 1061 } 1062} 1063 1064} // End llvm namespace 1065 1066#endif 1067