LoopInfo.h revision 887f9c5ec15582aec34aa6c28955d01e4e9961e2
1ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown//===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator -------*- C++ -*-===// 2ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// 3ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// The LLVM Compiler Infrastructure 4ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// 5ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// This file is distributed under the University of Illinois Open Source 6ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// License. See LICENSE.TXT for details. 7ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// 8ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown//===----------------------------------------------------------------------===// 9ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// 10436e89c602e787e7a27dd6624b09beed41a0da8aDmitriy Ivanov// This file defines the LoopInfo class that is used to identify natural loops 11ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// and determine the loop depth of various nodes of the CFG. A natural loop 12ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// has exactly one entry-point, which is called the header. Note that natural 13ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// loops may actually be several loops that share the same header node. 14ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// 15ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// This analysis calculates the nesting structure of loops in a function. For 16ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// each natural loop identified, this analysis identifies natural loops 17ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// contained entirely within the loop and the basic blocks the make up the loop. 18ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// 19ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// It can calculate on the fly various bits of information, for example: 20ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// 21ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// * whether there is a preheader for the loop 22ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// * the number of back edges to the header 23ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// * whether or not a particular block branches out of the loop 24ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// * the successor blocks of the loop 25ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// * the loop depth 26ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// * etc... 27ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// 28ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown//===----------------------------------------------------------------------===// 29ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 30ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown#ifndef LLVM_ANALYSIS_LOOPINFO_H 31ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown#define LLVM_ANALYSIS_LOOPINFO_H 32ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 33ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown#include "llvm/ADT/DenseMap.h" 34ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown#include "llvm/ADT/DenseSet.h" 35ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown#include "llvm/ADT/GraphTraits.h" 36ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown#include "llvm/ADT/SmallVector.h" 37ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown#include "llvm/Analysis/Dominators.h" 38ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown#include "llvm/Pass.h" 39ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown#include <algorithm> 40ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 41ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brownnamespace llvm { 42ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 43ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Browntemplate<typename T> 44ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Browninline void RemoveFromVector(std::vector<T*> &V, T *N) { 45ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown typename std::vector<T*>::iterator I = std::find(V.begin(), V.end(), N); 46ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown assert(I != V.end() && "N is not in this list!"); 47ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown V.erase(I); 48ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown} 49ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 50ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brownclass DominatorTree; 51ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brownclass LoopInfo; 52ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brownclass Loop; 53ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brownclass MDNode; 54ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brownclass PHINode; 55ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brownclass raw_ostream; 56ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Browntemplate<class N, class M> class LoopInfoBase; 57ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Browntemplate<class N, class M> class LoopBase; 58ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 59ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown//===----------------------------------------------------------------------===// 60ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown/// LoopBase class - Instances of this class are used to represent loops that 61ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown/// are detected in the flow graph 62ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown/// 63ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Browntemplate<class BlockT, class LoopT> 64ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brownclass LoopBase { 65ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown LoopT *ParentLoop; 66ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // SubLoops - Loops contained entirely within this one. 67ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown std::vector<LoopT *> SubLoops; 68ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 69ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // Blocks - The list of blocks in this loop. First entry is the header node. 70ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown std::vector<BlockT*> Blocks; 71ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 72ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown SmallPtrSet<const BlockT*, 8> DenseBlockSet; 73ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 74ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown LoopBase(const LoopBase<BlockT, LoopT> &) LLVM_DELETED_FUNCTION; 75ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown const LoopBase<BlockT, LoopT>& 76436e89c602e787e7a27dd6624b09beed41a0da8aDmitriy Ivanov operator=(const LoopBase<BlockT, LoopT> &) LLVM_DELETED_FUNCTION; 77436e89c602e787e7a27dd6624b09beed41a0da8aDmitriy Ivanovpublic: 78ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// Loop ctor - This creates an empty loop. 79ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown LoopBase() : ParentLoop(0) {} 80ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown ~LoopBase() { 81ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown for (size_t i = 0, e = SubLoops.size(); i != e; ++i) 82ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown delete SubLoops[i]; 83ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 84ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 85ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// getLoopDepth - Return the nesting level of this loop. An outer-most 86ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// loop has depth 1, for consistency with loop depth values used for basic 87ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// blocks, where depth 0 is used for blocks not inside any loops. 88ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown unsigned getLoopDepth() const { 89eb0bae136f4eeaaf29761dddb148b118fb824632Dmitriy Ivanov unsigned D = 1; 90eb0bae136f4eeaaf29761dddb148b118fb824632Dmitriy Ivanov for (const LoopT *CurLoop = ParentLoop; CurLoop; 91eb0bae136f4eeaaf29761dddb148b118fb824632Dmitriy Ivanov CurLoop = CurLoop->ParentLoop) 92eb0bae136f4eeaaf29761dddb148b118fb824632Dmitriy Ivanov ++D; 93eb0bae136f4eeaaf29761dddb148b118fb824632Dmitriy Ivanov return D; 94eb0bae136f4eeaaf29761dddb148b118fb824632Dmitriy Ivanov } 95ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown BlockT *getHeader() const { return Blocks.front(); } 96ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown LoopT *getParentLoop() const { return ParentLoop; } 97ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 98ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// setParentLoop is a raw interface for bypassing addChildLoop. 99ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown void setParentLoop(LoopT *L) { ParentLoop = L; } 100ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 101ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// contains - Return true if the specified loop is contained within in 102ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// this loop. 103ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 104ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown bool contains(const LoopT *L) const { 105ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown if (L == this) return true; 106ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown if (L == 0) return false; 107ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown return contains(L->getParentLoop()); 108436e89c602e787e7a27dd6624b09beed41a0da8aDmitriy Ivanov } 109ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 110ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// contains - Return true if the specified basic block is in this loop. 111ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 112ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown bool contains(const BlockT *BB) const { 113ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown return DenseBlockSet.count(BB); 114ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 115ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 116ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// contains - Return true if the specified instruction is in this loop. 117ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 118ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown template<class InstT> 119ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown bool contains(const InstT *Inst) const { 120ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown return contains(Inst->getParent()); 121ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 122ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 123ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// iterator/begin/end - Return the loops contained entirely within this loop. 124ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 125ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown const std::vector<LoopT *> &getSubLoops() const { return SubLoops; } 126ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown std::vector<LoopT *> &getSubLoopsVector() { return SubLoops; } 127ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown typedef typename std::vector<LoopT *>::const_iterator iterator; 128ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown typedef typename std::vector<LoopT *>::const_reverse_iterator 129ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown reverse_iterator; 130ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown iterator begin() const { return SubLoops.begin(); } 131ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown iterator end() const { return SubLoops.end(); } 132ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown reverse_iterator rbegin() const { return SubLoops.rbegin(); } 133ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown reverse_iterator rend() const { return SubLoops.rend(); } 134ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown bool empty() const { return SubLoops.empty(); } 135ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 136ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// getBlocks - Get a list of the basic blocks which make up this loop. 137ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 138ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown const std::vector<BlockT*> &getBlocks() const { return Blocks; } 139ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown typedef typename std::vector<BlockT*>::const_iterator block_iterator; 140ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown block_iterator block_begin() const { return Blocks.begin(); } 141ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown block_iterator block_end() const { return Blocks.end(); } 142ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 143ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// getNumBlocks - Get the number of blocks in this loop in constant time. 144ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown unsigned getNumBlocks() const { 145ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown return Blocks.size(); 146ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 147ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 148ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// isLoopExiting - True if terminator in the block can branch to another 149ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// block that is outside of the current loop. 150ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 151ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown bool isLoopExiting(const BlockT *BB) const { 152ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown typedef GraphTraits<const BlockT*> BlockTraits; 153ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown for (typename BlockTraits::ChildIteratorType SI = 154ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown BlockTraits::child_begin(BB), 155ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown SE = BlockTraits::child_end(BB); SI != SE; ++SI) { 156ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown if (!contains(*SI)) 157ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown return true; 158ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 159ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown return false; 160ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 161663860b1408516d02ebfcb3a9999a134e6cfb223Ben Cheng 162663860b1408516d02ebfcb3a9999a134e6cfb223Ben Cheng /// getNumBackEdges - Calculate the number of back edges to the loop header 163663860b1408516d02ebfcb3a9999a134e6cfb223Ben Cheng /// 164663860b1408516d02ebfcb3a9999a134e6cfb223Ben Cheng unsigned getNumBackEdges() const { 165663860b1408516d02ebfcb3a9999a134e6cfb223Ben Cheng unsigned NumBackEdges = 0; 166663860b1408516d02ebfcb3a9999a134e6cfb223Ben Cheng BlockT *H = getHeader(); 167663860b1408516d02ebfcb3a9999a134e6cfb223Ben Cheng 168663860b1408516d02ebfcb3a9999a134e6cfb223Ben Cheng typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits; 169663860b1408516d02ebfcb3a9999a134e6cfb223Ben Cheng for (typename InvBlockTraits::ChildIteratorType I = 170663860b1408516d02ebfcb3a9999a134e6cfb223Ben Cheng InvBlockTraits::child_begin(H), 171663860b1408516d02ebfcb3a9999a134e6cfb223Ben Cheng E = InvBlockTraits::child_end(H); I != E; ++I) 172ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown if (contains(*I)) 173ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown ++NumBackEdges; 174ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 175ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown return NumBackEdges; 176ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 177ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 178ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown //===--------------------------------------------------------------------===// 179ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // APIs for simple analysis of the loop. 180ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // 181ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // Note that all of these methods can fail on general loops (ie, there may not 182ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // be a preheader, etc). For best success, the loop simplification and 183ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // induction variable canonicalization pass should be used to normalize loops 184ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // for easy analysis. These methods assume canonical loops. 185ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 186ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// getExitingBlocks - Return all blocks inside the loop that have successors 187ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// outside of the loop. These are the blocks _inside of the current loop_ 188ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// which branch out. The returned list is always unique. 189ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 190ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const; 191ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 192ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// getExitingBlock - If getExitingBlocks would return exactly one block, 193ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// return that block. Otherwise return null. 194ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown BlockT *getExitingBlock() const; 195ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 196ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// getExitBlocks - Return all of the successor blocks of this loop. These 197ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// are the blocks _outside of the current loop_ which are branched to. 198ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 199ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown void getExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const; 200ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 201ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// getExitBlock - If getExitBlocks would return exactly one block, 202ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// return that block. Otherwise return null. 203ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown BlockT *getExitBlock() const; 204ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 205ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// Edge type. 206ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown typedef std::pair<const BlockT*, const BlockT*> Edge; 207ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 208ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// getExitEdges - Return all pairs of (_inside_block_,_outside_block_). 209ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown void getExitEdges(SmallVectorImpl<Edge> &ExitEdges) const; 210ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 211ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// getLoopPreheader - If there is a preheader for this loop, return it. A 212ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// loop has a preheader if there is only one edge to the header of the loop 213ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// from outside of the loop. If this is the case, the block branching to the 214ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// header of the loop is the preheader node. 215ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 216ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// This method returns null if there is no preheader for the loop. 217ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 218ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown BlockT *getLoopPreheader() const; 219ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 220ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// getLoopPredecessor - If the given loop's header has exactly one unique 221ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// predecessor outside the loop, return it. Otherwise return null. 222ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// This is less strict that the loop "preheader" concept, which requires 223ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// the predecessor to have exactly one successor. 224ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 225ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown BlockT *getLoopPredecessor() const; 226ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 227ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// getLoopLatch - If there is a single latch block for this loop, return it. 228ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// A latch block is a block that contains a branch back to the header. 229ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown BlockT *getLoopLatch() const; 230ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 231ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown //===--------------------------------------------------------------------===// 232ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // APIs for updating loop information after changing the CFG 233ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // 234ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 235ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// addBasicBlockToLoop - This method is used by other analyses to update loop 236ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// information. NewBB is set to be a new member of the current loop. 237ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// Because of this, it is added as a member of all parent loops, and is added 238ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// to the specified LoopInfo object as being in the current basic block. It 239ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// is not valid to replace the loop header with this method. 240ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 241ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown void addBasicBlockToLoop(BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &LI); 242ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 243b32f58018498ea2225959b0ba11c18f0c433deefEvgeniy Stepanov /// replaceChildLoopWith - This is used when splitting loops up. It replaces 244ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// the OldChild entry in our children list with NewChild, and updates the 245ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// parent pointer of OldChild to be null and the NewChild to be this loop. 246ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// This updates the loop depth of the new child. 247ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown void replaceChildLoopWith(LoopT *OldChild, LoopT *NewChild); 248ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 249b32f58018498ea2225959b0ba11c18f0c433deefEvgeniy Stepanov /// addChildLoop - Add the specified loop to be a child of this loop. This 250b32f58018498ea2225959b0ba11c18f0c433deefEvgeniy Stepanov /// updates the loop depth of the new child. 251b32f58018498ea2225959b0ba11c18f0c433deefEvgeniy Stepanov /// 252b32f58018498ea2225959b0ba11c18f0c433deefEvgeniy Stepanov void addChildLoop(LoopT *NewChild) { 253b32f58018498ea2225959b0ba11c18f0c433deefEvgeniy Stepanov assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!"); 254b32f58018498ea2225959b0ba11c18f0c433deefEvgeniy Stepanov NewChild->ParentLoop = static_cast<LoopT *>(this); 255ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown SubLoops.push_back(NewChild); 256ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 257ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 258ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// removeChildLoop - This removes the specified child from being a subloop of 259ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// this loop. The loop is not deleted, as it will presumably be inserted 260ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// into another loop. 261ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown LoopT *removeChildLoop(iterator I) { 262ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown assert(I != SubLoops.end() && "Cannot remove end iterator!"); 263ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown LoopT *Child = *I; 264ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown assert(Child->ParentLoop == this && "Child is not a child of this loop!"); 265ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown SubLoops.erase(SubLoops.begin()+(I-begin())); 266ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown Child->ParentLoop = 0; 267ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown return Child; 268ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 269ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 270ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// addBlockEntry - This adds a basic block directly to the basic block list. 271ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// This should only be used by transformations that create new loops. Other 272ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// transformations should use addBasicBlockToLoop. 273ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown void addBlockEntry(BlockT *BB) { 274ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown Blocks.push_back(BB); 275436e89c602e787e7a27dd6624b09beed41a0da8aDmitriy Ivanov DenseBlockSet.insert(BB); 276ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 277ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 278ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// reverseBlocks - interface to reverse Blocks[from, end of loop] in this loop 279ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown void reverseBlock(unsigned from) { 280436e89c602e787e7a27dd6624b09beed41a0da8aDmitriy Ivanov std::reverse(Blocks.begin() + from, Blocks.end()); 281ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 282ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 283ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// reserveBlocks- interface to do reserve() for Blocks 284ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown void reserveBlocks(unsigned size) { 285ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown Blocks.reserve(size); 286ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 287ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 288ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// moveToHeader - This method is used to move BB (which must be part of this 289ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// loop) to be the loop header of the loop (the block that dominates all 290ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// others). 291ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown void moveToHeader(BlockT *BB) { 292ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown if (Blocks[0] == BB) return; 293ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown for (unsigned i = 0; ; ++i) { 294ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown assert(i != Blocks.size() && "Loop does not contain BB!"); 295ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown if (Blocks[i] == BB) { 296ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown Blocks[i] = Blocks[0]; 297ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown Blocks[0] = BB; 298ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown return; 299ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 300ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 301ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 302ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 303ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// removeBlockFromLoop - This removes the specified basic block from the 304ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// current loop, updating the Blocks as appropriate. This does not update 305ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// the mapping in the LoopInfo class. 306436e89c602e787e7a27dd6624b09beed41a0da8aDmitriy Ivanov void removeBlockFromLoop(BlockT *BB) { 307ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown RemoveFromVector(Blocks, BB); 308ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown DenseBlockSet.erase(BB); 309ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 310ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 311ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// verifyLoop - Verify loop structure 312ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown void verifyLoop() const; 313ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 314ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// verifyLoop - Verify loop structure of this loop and all nested loops. 315ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown void verifyLoopNest(DenseSet<const LoopT*> *Loops) const; 316ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 317ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown void print(raw_ostream &OS, unsigned Depth = 0) const; 318436e89c602e787e7a27dd6624b09beed41a0da8aDmitriy Ivanov 319ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brownprotected: 320ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown friend class LoopInfoBase<BlockT, LoopT>; 321ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown explicit LoopBase(BlockT *BB) : ParentLoop(0) { 322ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown Blocks.push_back(BB); 323ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown DenseBlockSet.insert(BB); 324ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown } 325ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown}; 326ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 327ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Browntemplate<class BlockT, class LoopT> 328ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brownraw_ostream& operator<<(raw_ostream &OS, const LoopBase<BlockT, LoopT> &Loop) { 329ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown Loop.print(OS); 330ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown return OS; 331ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown} 332ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 333ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// Implementation in LoopInfoImpl.h 334ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown#ifdef __GNUC__ 335ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown__extension__ extern template class LoopBase<BasicBlock, Loop>; 336ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown#endif 337663860b1408516d02ebfcb3a9999a134e6cfb223Ben Cheng 338436e89c602e787e7a27dd6624b09beed41a0da8aDmitriy Ivanovclass Loop : public LoopBase<BasicBlock, Loop> { 339436e89c602e787e7a27dd6624b09beed41a0da8aDmitriy Ivanovpublic: 340ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown Loop() {} 341ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 342ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// isLoopInvariant - Return true if the specified value is loop invariant 343ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 344ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown bool isLoopInvariant(Value *V) const; 345ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 346ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// hasLoopInvariantOperands - Return true if all the operands of the 347ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// specified instruction are loop invariant. 348ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown bool hasLoopInvariantOperands(Instruction *I) const; 349ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 350ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// makeLoopInvariant - If the given value is an instruction inside of the 351ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// loop and it can be hoisted, do so to make it trivially loop-invariant. 352ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// Return true if the value after any hoisting is loop invariant. This 353ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// function can be used as a slightly more aggressive replacement for 354ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// isLoopInvariant. 355ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 356eb0bae136f4eeaaf29761dddb148b118fb824632Dmitriy Ivanov /// If InsertPt is specified, it is the point to hoist instructions to. 357ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// If null, the terminator of the loop preheader is used. 358ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 359ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown bool makeLoopInvariant(Value *V, bool &Changed, 360ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown Instruction *InsertPt = 0) const; 361ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 362ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// makeLoopInvariant - If the given instruction is inside of the 363ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// loop and it can be hoisted, do so to make it trivially loop-invariant. 364ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// Return true if the instruction after any hoisting is loop invariant. This 365ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// function can be used as a slightly more aggressive replacement for 366ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// isLoopInvariant. 367ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 368ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// If InsertPt is specified, it is the point to hoist instructions to. 369ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// If null, the terminator of the loop preheader is used. 370ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 371ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown bool makeLoopInvariant(Instruction *I, bool &Changed, 372ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown Instruction *InsertPt = 0) const; 373ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 374ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// getCanonicalInductionVariable - Check to see if the loop has a canonical 375ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// induction variable: an integer recurrence that starts at 0 and increments 376ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// by one each time through the loop. If so, return the phi node that 377ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// corresponds to it. 378ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 379ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// The IndVarSimplify pass transforms loops to have a canonical induction 380ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// variable. 381ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// 382ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown PHINode *getCanonicalInductionVariable() const; 383ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 384ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// isLCSSAForm - Return true if the Loop is in LCSSA form 385ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown bool isLCSSAForm(DominatorTree &DT) const; 386ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 387ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// isLoopSimplifyForm - Return true if the Loop is in the form that 388ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// the LoopSimplify form transforms loops to, which is sometimes called 389ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown /// normal form. 390ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown bool isLoopSimplifyForm() const; 391 392 /// isSafeToClone - Return true if the loop body is safe to clone in practice. 393 bool isSafeToClone() const; 394 395 /// Returns true if the loop is annotated parallel. 396 /// 397 /// A parallel loop can be assumed to not contain any dependencies between 398 /// iterations by the compiler. That is, any loop-carried dependency checking 399 /// can be skipped completely when parallelizing the loop on the target 400 /// machine. Thus, if the parallel loop information originates from the 401 /// programmer, e.g. via the OpenMP parallel for pragma, it is the 402 /// programmer's responsibility to ensure there are no loop-carried 403 /// dependencies. The final execution order of the instructions across 404 /// iterations is not guaranteed, thus, the end result might or might not 405 /// implement actual concurrent execution of instructions across multiple 406 /// iterations. 407 bool isAnnotatedParallel() const; 408 409 /// Return the llvm.loop loop id metadata node for this loop if it is present. 410 /// 411 /// If this loop contains the same llvm.loop metadata on each branch to the 412 /// header then the node is returned. If any latch instruction does not 413 /// contain llvm.loop or or if multiple latches contain different nodes then 414 /// 0 is returned. 415 MDNode *getLoopID() const; 416 /// Set the llvm.loop loop id metadata for this loop. 417 /// 418 /// The LoopID metadata node will be added to each terminator instruction in 419 /// the loop that branches to the loop header. 420 /// 421 /// The LoopID metadata node should have one or more operands and the first 422 /// operand should should be the node itself. 423 void setLoopID(MDNode *LoopID) const; 424 425 /// hasDedicatedExits - Return true if no exit block for the loop 426 /// has a predecessor that is outside the loop. 427 bool hasDedicatedExits() const; 428 429 /// getUniqueExitBlocks - Return all unique successor blocks of this loop. 430 /// These are the blocks _outside of the current loop_ which are branched to. 431 /// This assumes that loop exits are in canonical form. 432 /// 433 void getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const; 434 435 /// getUniqueExitBlock - If getUniqueExitBlocks would return exactly one 436 /// block, return that block. Otherwise return null. 437 BasicBlock *getUniqueExitBlock() const; 438 439 void dump() const; 440 441private: 442 friend class LoopInfoBase<BasicBlock, Loop>; 443 explicit Loop(BasicBlock *BB) : LoopBase<BasicBlock, Loop>(BB) {} 444}; 445 446//===----------------------------------------------------------------------===// 447/// LoopInfo - This class builds and contains all of the top level loop 448/// structures in the specified function. 449/// 450 451template<class BlockT, class LoopT> 452class LoopInfoBase { 453 // BBMap - Mapping of basic blocks to the inner most loop they occur in 454 DenseMap<BlockT *, LoopT *> BBMap; 455 std::vector<LoopT *> TopLevelLoops; 456 friend class LoopBase<BlockT, LoopT>; 457 friend class LoopInfo; 458 459 void operator=(const LoopInfoBase &) LLVM_DELETED_FUNCTION; 460 LoopInfoBase(const LoopInfo &) LLVM_DELETED_FUNCTION; 461public: 462 LoopInfoBase() { } 463 ~LoopInfoBase() { releaseMemory(); } 464 465 void releaseMemory() { 466 for (typename std::vector<LoopT *>::iterator I = 467 TopLevelLoops.begin(), E = TopLevelLoops.end(); I != E; ++I) 468 delete *I; // Delete all of the loops... 469 470 BBMap.clear(); // Reset internal state of analysis 471 TopLevelLoops.clear(); 472 } 473 474 /// iterator/begin/end - The interface to the top-level loops in the current 475 /// function. 476 /// 477 typedef typename std::vector<LoopT *>::const_iterator iterator; 478 typedef typename std::vector<LoopT *>::const_reverse_iterator 479 reverse_iterator; 480 iterator begin() const { return TopLevelLoops.begin(); } 481 iterator end() const { return TopLevelLoops.end(); } 482 reverse_iterator rbegin() const { return TopLevelLoops.rbegin(); } 483 reverse_iterator rend() const { return TopLevelLoops.rend(); } 484 bool empty() const { return TopLevelLoops.empty(); } 485 486 /// getLoopFor - Return the inner most loop that BB lives in. If a basic 487 /// block is in no loop (for example the entry node), null is returned. 488 /// 489 LoopT *getLoopFor(const BlockT *BB) const { 490 return BBMap.lookup(const_cast<BlockT*>(BB)); 491 } 492 493 /// operator[] - same as getLoopFor... 494 /// 495 const LoopT *operator[](const BlockT *BB) const { 496 return getLoopFor(BB); 497 } 498 499 /// getLoopDepth - Return the loop nesting level of the specified block. A 500 /// depth of 0 means the block is not inside any loop. 501 /// 502 unsigned getLoopDepth(const BlockT *BB) const { 503 const LoopT *L = getLoopFor(BB); 504 return L ? L->getLoopDepth() : 0; 505 } 506 507 // isLoopHeader - True if the block is a loop header node 508 bool isLoopHeader(BlockT *BB) const { 509 const LoopT *L = getLoopFor(BB); 510 return L && L->getHeader() == BB; 511 } 512 513 /// removeLoop - This removes the specified top-level loop from this loop info 514 /// object. The loop is not deleted, as it will presumably be inserted into 515 /// another loop. 516 LoopT *removeLoop(iterator I) { 517 assert(I != end() && "Cannot remove end iterator!"); 518 LoopT *L = *I; 519 assert(L->getParentLoop() == 0 && "Not a top-level loop!"); 520 TopLevelLoops.erase(TopLevelLoops.begin() + (I-begin())); 521 return L; 522 } 523 524 /// changeLoopFor - Change the top-level loop that contains BB to the 525 /// specified loop. This should be used by transformations that restructure 526 /// the loop hierarchy tree. 527 void changeLoopFor(BlockT *BB, LoopT *L) { 528 if (!L) { 529 BBMap.erase(BB); 530 return; 531 } 532 BBMap[BB] = L; 533 } 534 535 /// changeTopLevelLoop - Replace the specified loop in the top-level loops 536 /// list with the indicated loop. 537 void changeTopLevelLoop(LoopT *OldLoop, 538 LoopT *NewLoop) { 539 typename std::vector<LoopT *>::iterator I = 540 std::find(TopLevelLoops.begin(), TopLevelLoops.end(), OldLoop); 541 assert(I != TopLevelLoops.end() && "Old loop not at top level!"); 542 *I = NewLoop; 543 assert(NewLoop->ParentLoop == 0 && OldLoop->ParentLoop == 0 && 544 "Loops already embedded into a subloop!"); 545 } 546 547 /// addTopLevelLoop - This adds the specified loop to the collection of 548 /// top-level loops. 549 void addTopLevelLoop(LoopT *New) { 550 assert(New->getParentLoop() == 0 && "Loop already in subloop!"); 551 TopLevelLoops.push_back(New); 552 } 553 554 /// removeBlock - This method completely removes BB from all data structures, 555 /// including all of the Loop objects it is nested in and our mapping from 556 /// BasicBlocks to loops. 557 void removeBlock(BlockT *BB) { 558 typename DenseMap<BlockT *, LoopT *>::iterator I = BBMap.find(BB); 559 if (I != BBMap.end()) { 560 for (LoopT *L = I->second; L; L = L->getParentLoop()) 561 L->removeBlockFromLoop(BB); 562 563 BBMap.erase(I); 564 } 565 } 566 567 // Internals 568 569 static bool isNotAlreadyContainedIn(const LoopT *SubLoop, 570 const LoopT *ParentLoop) { 571 if (SubLoop == 0) return true; 572 if (SubLoop == ParentLoop) return false; 573 return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop); 574 } 575 576 /// Create the loop forest using a stable algorithm. 577 void Analyze(DominatorTreeBase<BlockT> &DomTree); 578 579 // Debugging 580 581 void print(raw_ostream &OS) const; 582}; 583 584// Implementation in LoopInfoImpl.h 585#ifdef __GNUC__ 586__extension__ extern template class LoopInfoBase<BasicBlock, Loop>; 587#endif 588 589class LoopInfo : public FunctionPass { 590 LoopInfoBase<BasicBlock, Loop> LI; 591 friend class LoopBase<BasicBlock, Loop>; 592 593 void operator=(const LoopInfo &) LLVM_DELETED_FUNCTION; 594 LoopInfo(const LoopInfo &) LLVM_DELETED_FUNCTION; 595public: 596 static char ID; // Pass identification, replacement for typeid 597 598 LoopInfo() : FunctionPass(ID) { 599 initializeLoopInfoPass(*PassRegistry::getPassRegistry()); 600 } 601 602 LoopInfoBase<BasicBlock, Loop>& getBase() { return LI; } 603 604 /// iterator/begin/end - The interface to the top-level loops in the current 605 /// function. 606 /// 607 typedef LoopInfoBase<BasicBlock, Loop>::iterator iterator; 608 typedef LoopInfoBase<BasicBlock, Loop>::reverse_iterator reverse_iterator; 609 inline iterator begin() const { return LI.begin(); } 610 inline iterator end() const { return LI.end(); } 611 inline reverse_iterator rbegin() const { return LI.rbegin(); } 612 inline reverse_iterator rend() const { return LI.rend(); } 613 bool empty() const { return LI.empty(); } 614 615 /// getLoopFor - Return the inner most loop that BB lives in. If a basic 616 /// block is in no loop (for example the entry node), null is returned. 617 /// 618 inline Loop *getLoopFor(const BasicBlock *BB) const { 619 return LI.getLoopFor(BB); 620 } 621 622 /// operator[] - same as getLoopFor... 623 /// 624 inline const Loop *operator[](const BasicBlock *BB) const { 625 return LI.getLoopFor(BB); 626 } 627 628 /// getLoopDepth - Return the loop nesting level of the specified block. A 629 /// depth of 0 means the block is not inside any loop. 630 /// 631 inline unsigned getLoopDepth(const BasicBlock *BB) const { 632 return LI.getLoopDepth(BB); 633 } 634 635 // isLoopHeader - True if the block is a loop header node 636 inline bool isLoopHeader(BasicBlock *BB) const { 637 return LI.isLoopHeader(BB); 638 } 639 640 /// runOnFunction - Calculate the natural loop information. 641 /// 642 virtual bool runOnFunction(Function &F); 643 644 virtual void verifyAnalysis() const; 645 646 virtual void releaseMemory() { LI.releaseMemory(); } 647 648 virtual void print(raw_ostream &O, const Module* M = 0) const; 649 650 virtual void getAnalysisUsage(AnalysisUsage &AU) const; 651 652 /// removeLoop - This removes the specified top-level loop from this loop info 653 /// object. The loop is not deleted, as it will presumably be inserted into 654 /// another loop. 655 inline Loop *removeLoop(iterator I) { return LI.removeLoop(I); } 656 657 /// changeLoopFor - Change the top-level loop that contains BB to the 658 /// specified loop. This should be used by transformations that restructure 659 /// the loop hierarchy tree. 660 inline void changeLoopFor(BasicBlock *BB, Loop *L) { 661 LI.changeLoopFor(BB, L); 662 } 663 664 /// changeTopLevelLoop - Replace the specified loop in the top-level loops 665 /// list with the indicated loop. 666 inline void changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop) { 667 LI.changeTopLevelLoop(OldLoop, NewLoop); 668 } 669 670 /// addTopLevelLoop - This adds the specified loop to the collection of 671 /// top-level loops. 672 inline void addTopLevelLoop(Loop *New) { 673 LI.addTopLevelLoop(New); 674 } 675 676 /// removeBlock - This method completely removes BB from all data structures, 677 /// including all of the Loop objects it is nested in and our mapping from 678 /// BasicBlocks to loops. 679 void removeBlock(BasicBlock *BB) { 680 LI.removeBlock(BB); 681 } 682 683 /// updateUnloop - Update LoopInfo after removing the last backedge from a 684 /// loop--now the "unloop". This updates the loop forest and parent loops for 685 /// each block so that Unloop is no longer referenced, but the caller must 686 /// actually delete the Unloop object. 687 void updateUnloop(Loop *Unloop); 688 689 /// replacementPreservesLCSSAForm - Returns true if replacing From with To 690 /// everywhere is guaranteed to preserve LCSSA form. 691 bool replacementPreservesLCSSAForm(Instruction *From, Value *To) { 692 // Preserving LCSSA form is only problematic if the replacing value is an 693 // instruction. 694 Instruction *I = dyn_cast<Instruction>(To); 695 if (!I) return true; 696 // If both instructions are defined in the same basic block then replacement 697 // cannot break LCSSA form. 698 if (I->getParent() == From->getParent()) 699 return true; 700 // If the instruction is not defined in a loop then it can safely replace 701 // anything. 702 Loop *ToLoop = getLoopFor(I->getParent()); 703 if (!ToLoop) return true; 704 // If the replacing instruction is defined in the same loop as the original 705 // instruction, or in a loop that contains it as an inner loop, then using 706 // it as a replacement will not break LCSSA form. 707 return ToLoop->contains(getLoopFor(From->getParent())); 708 } 709}; 710 711 712// Allow clients to walk the list of nested loops... 713template <> struct GraphTraits<const Loop*> { 714 typedef const Loop NodeType; 715 typedef LoopInfo::iterator ChildIteratorType; 716 717 static NodeType *getEntryNode(const Loop *L) { return L; } 718 static inline ChildIteratorType child_begin(NodeType *N) { 719 return N->begin(); 720 } 721 static inline ChildIteratorType child_end(NodeType *N) { 722 return N->end(); 723 } 724}; 725 726template <> struct GraphTraits<Loop*> { 727 typedef Loop NodeType; 728 typedef LoopInfo::iterator ChildIteratorType; 729 730 static NodeType *getEntryNode(Loop *L) { return L; } 731 static inline ChildIteratorType child_begin(NodeType *N) { 732 return N->begin(); 733 } 734 static inline ChildIteratorType child_end(NodeType *N) { 735 return N->end(); 736 } 737}; 738 739} // End llvm namespace 740 741#endif 742