MachineBasicBlock.h revision 853d3fb8d24fab2258e9cd5dce3ec8ff4189eeda
1//===-- llvm/CodeGen/MachineBasicBlock.h ------------------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// Collect the sequence of machine instructions for a basic block. 11// 12//===----------------------------------------------------------------------===// 13 14#ifndef LLVM_CODEGEN_MACHINEBASICBLOCK_H 15#define LLVM_CODEGEN_MACHINEBASICBLOCK_H 16 17#include "llvm/CodeGen/MachineInstr.h" 18#include "llvm/ADT/GraphTraits.h" 19 20namespace llvm { 21 22class Pass; 23class BasicBlock; 24class MachineFunction; 25class MCSymbol; 26class StringRef; 27class raw_ostream; 28 29template <> 30struct ilist_traits<MachineInstr> : public ilist_default_traits<MachineInstr> { 31private: 32 mutable ilist_half_node<MachineInstr> Sentinel; 33 34 // this is only set by the MachineBasicBlock owning the LiveList 35 friend class MachineBasicBlock; 36 MachineBasicBlock* Parent; 37 38public: 39 MachineInstr *createSentinel() const { 40 return static_cast<MachineInstr*>(&Sentinel); 41 } 42 void destroySentinel(MachineInstr *) const {} 43 44 MachineInstr *provideInitialHead() const { return createSentinel(); } 45 MachineInstr *ensureHead(MachineInstr*) const { return createSentinel(); } 46 static void noteHead(MachineInstr*, MachineInstr*) {} 47 48 void addNodeToList(MachineInstr* N); 49 void removeNodeFromList(MachineInstr* N); 50 void transferNodesFromList(ilist_traits &SrcTraits, 51 ilist_iterator<MachineInstr> first, 52 ilist_iterator<MachineInstr> last); 53 void deleteNode(MachineInstr *N); 54private: 55 void createNode(const MachineInstr &); 56}; 57 58class MachineBasicBlock : public ilist_node<MachineBasicBlock> { 59 typedef ilist<MachineInstr> Instructions; 60 Instructions Insts; 61 const BasicBlock *BB; 62 int Number; 63 MachineFunction *xParent; 64 65 /// Predecessors/Successors - Keep track of the predecessor / successor 66 /// basicblocks. 67 std::vector<MachineBasicBlock *> Predecessors; 68 std::vector<MachineBasicBlock *> Successors; 69 70 /// LiveIns - Keep track of the physical registers that are livein of 71 /// the basicblock. 72 std::vector<unsigned> LiveIns; 73 74 /// Alignment - Alignment of the basic block. Zero if the basic block does 75 /// not need to be aligned. 76 unsigned Alignment; 77 78 /// IsLandingPad - Indicate that this basic block is entered via an 79 /// exception handler. 80 bool IsLandingPad; 81 82 /// AddressTaken - Indicate that this basic block is potentially the 83 /// target of an indirect branch. 84 bool AddressTaken; 85 86 // Intrusive list support 87 MachineBasicBlock() {} 88 89 explicit MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb); 90 91 ~MachineBasicBlock(); 92 93 // MachineBasicBlocks are allocated and owned by MachineFunction. 94 friend class MachineFunction; 95 96public: 97 /// getBasicBlock - Return the LLVM basic block that this instance 98 /// corresponded to originally. Note that this may be NULL if this instance 99 /// does not correspond directly to an LLVM basic block. 100 /// 101 const BasicBlock *getBasicBlock() const { return BB; } 102 103 /// getName - Return the name of the corresponding LLVM basic block, or 104 /// "(null)". 105 StringRef getName() const; 106 107 /// hasAddressTaken - Test whether this block is potentially the target 108 /// of an indirect branch. 109 bool hasAddressTaken() const { return AddressTaken; } 110 111 /// setHasAddressTaken - Set this block to reflect that it potentially 112 /// is the target of an indirect branch. 113 void setHasAddressTaken() { AddressTaken = true; } 114 115 /// getParent - Return the MachineFunction containing this basic block. 116 /// 117 const MachineFunction *getParent() const { return xParent; } 118 MachineFunction *getParent() { return xParent; } 119 120 typedef Instructions::iterator iterator; 121 typedef Instructions::const_iterator const_iterator; 122 typedef std::reverse_iterator<const_iterator> const_reverse_iterator; 123 typedef std::reverse_iterator<iterator> reverse_iterator; 124 125 unsigned size() const { return (unsigned)Insts.size(); } 126 bool empty() const { return Insts.empty(); } 127 128 MachineInstr& front() { return Insts.front(); } 129 MachineInstr& back() { return Insts.back(); } 130 const MachineInstr& front() const { return Insts.front(); } 131 const MachineInstr& back() const { return Insts.back(); } 132 133 iterator begin() { return Insts.begin(); } 134 const_iterator begin() const { return Insts.begin(); } 135 iterator end() { return Insts.end(); } 136 const_iterator end() const { return Insts.end(); } 137 reverse_iterator rbegin() { return Insts.rbegin(); } 138 const_reverse_iterator rbegin() const { return Insts.rbegin(); } 139 reverse_iterator rend () { return Insts.rend(); } 140 const_reverse_iterator rend () const { return Insts.rend(); } 141 142 // Machine-CFG iterators 143 typedef std::vector<MachineBasicBlock *>::iterator pred_iterator; 144 typedef std::vector<MachineBasicBlock *>::const_iterator const_pred_iterator; 145 typedef std::vector<MachineBasicBlock *>::iterator succ_iterator; 146 typedef std::vector<MachineBasicBlock *>::const_iterator const_succ_iterator; 147 typedef std::vector<MachineBasicBlock *>::reverse_iterator 148 pred_reverse_iterator; 149 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator 150 const_pred_reverse_iterator; 151 typedef std::vector<MachineBasicBlock *>::reverse_iterator 152 succ_reverse_iterator; 153 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator 154 const_succ_reverse_iterator; 155 156 pred_iterator pred_begin() { return Predecessors.begin(); } 157 const_pred_iterator pred_begin() const { return Predecessors.begin(); } 158 pred_iterator pred_end() { return Predecessors.end(); } 159 const_pred_iterator pred_end() const { return Predecessors.end(); } 160 pred_reverse_iterator pred_rbegin() 161 { return Predecessors.rbegin();} 162 const_pred_reverse_iterator pred_rbegin() const 163 { return Predecessors.rbegin();} 164 pred_reverse_iterator pred_rend() 165 { return Predecessors.rend(); } 166 const_pred_reverse_iterator pred_rend() const 167 { return Predecessors.rend(); } 168 unsigned pred_size() const { 169 return (unsigned)Predecessors.size(); 170 } 171 bool pred_empty() const { return Predecessors.empty(); } 172 succ_iterator succ_begin() { return Successors.begin(); } 173 const_succ_iterator succ_begin() const { return Successors.begin(); } 174 succ_iterator succ_end() { return Successors.end(); } 175 const_succ_iterator succ_end() const { return Successors.end(); } 176 succ_reverse_iterator succ_rbegin() 177 { return Successors.rbegin(); } 178 const_succ_reverse_iterator succ_rbegin() const 179 { return Successors.rbegin(); } 180 succ_reverse_iterator succ_rend() 181 { return Successors.rend(); } 182 const_succ_reverse_iterator succ_rend() const 183 { return Successors.rend(); } 184 unsigned succ_size() const { 185 return (unsigned)Successors.size(); 186 } 187 bool succ_empty() const { return Successors.empty(); } 188 189 // LiveIn management methods. 190 191 /// addLiveIn - Add the specified register as a live in. Note that it 192 /// is an error to add the same register to the same set more than once. 193 void addLiveIn(unsigned Reg) { LiveIns.push_back(Reg); } 194 195 /// removeLiveIn - Remove the specified register from the live in set. 196 /// 197 void removeLiveIn(unsigned Reg); 198 199 /// isLiveIn - Return true if the specified register is in the live in set. 200 /// 201 bool isLiveIn(unsigned Reg) const; 202 203 // Iteration support for live in sets. These sets are kept in sorted 204 // order by their register number. 205 typedef std::vector<unsigned>::const_iterator livein_iterator; 206 livein_iterator livein_begin() const { return LiveIns.begin(); } 207 livein_iterator livein_end() const { return LiveIns.end(); } 208 bool livein_empty() const { return LiveIns.empty(); } 209 210 /// getAlignment - Return alignment of the basic block. 211 /// 212 unsigned getAlignment() const { return Alignment; } 213 214 /// setAlignment - Set alignment of the basic block. 215 /// 216 void setAlignment(unsigned Align) { Alignment = Align; } 217 218 /// isLandingPad - Returns true if the block is a landing pad. That is 219 /// this basic block is entered via an exception handler. 220 bool isLandingPad() const { return IsLandingPad; } 221 222 /// setIsLandingPad - Indicates the block is a landing pad. That is 223 /// this basic block is entered via an exception handler. 224 void setIsLandingPad() { IsLandingPad = true; } 225 226 // Code Layout methods. 227 228 /// moveBefore/moveAfter - move 'this' block before or after the specified 229 /// block. This only moves the block, it does not modify the CFG or adjust 230 /// potential fall-throughs at the end of the block. 231 void moveBefore(MachineBasicBlock *NewAfter); 232 void moveAfter(MachineBasicBlock *NewBefore); 233 234 /// updateTerminator - Update the terminator instructions in block to account 235 /// for changes to the layout. If the block previously used a fallthrough, 236 /// it may now need a branch, and if it previously used branching it may now 237 /// be able to use a fallthrough. 238 void updateTerminator(); 239 240 // Machine-CFG mutators 241 242 /// addSuccessor - Add succ as a successor of this MachineBasicBlock. 243 /// The Predecessors list of succ is automatically updated. 244 /// 245 void addSuccessor(MachineBasicBlock *succ); 246 247 /// removeSuccessor - Remove successor from the successors list of this 248 /// MachineBasicBlock. The Predecessors list of succ is automatically updated. 249 /// 250 void removeSuccessor(MachineBasicBlock *succ); 251 252 /// removeSuccessor - Remove specified successor from the successors list of 253 /// this MachineBasicBlock. The Predecessors list of succ is automatically 254 /// updated. Return the iterator to the element after the one removed. 255 /// 256 succ_iterator removeSuccessor(succ_iterator I); 257 258 /// transferSuccessors - Transfers all the successors from MBB to this 259 /// machine basic block (i.e., copies all the successors fromMBB and 260 /// remove all the successors from fromMBB). 261 void transferSuccessors(MachineBasicBlock *fromMBB); 262 263 /// isSuccessor - Return true if the specified MBB is a successor of this 264 /// block. 265 bool isSuccessor(const MachineBasicBlock *MBB) const; 266 267 /// isLayoutSuccessor - Return true if the specified MBB will be emitted 268 /// immediately after this block, such that if this block exits by 269 /// falling through, control will transfer to the specified MBB. Note 270 /// that MBB need not be a successor at all, for example if this block 271 /// ends with an unconditional branch to some other block. 272 bool isLayoutSuccessor(const MachineBasicBlock *MBB) const; 273 274 /// canFallThrough - Return true if the block can implicitly transfer 275 /// control to the block after it by falling off the end of it. This should 276 /// return false if it can reach the block after it, but it uses an explicit 277 /// branch to do so (e.g., a table jump). True is a conservative answer. 278 bool canFallThrough(); 279 280 /// getFirstTerminator - returns an iterator to the first terminator 281 /// instruction of this basic block. If a terminator does not exist, 282 /// it returns end() 283 iterator getFirstTerminator(); 284 285 /// SplitCriticalEdge - Split the critical edge from this block to the 286 /// given successor block, and return the newly created block, or null 287 /// if splitting is not possible. 288 /// 289 /// This function updates LiveVariables, MachineDominatorTree, and 290 /// MachineLoopInfo, as applicable. 291 MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P); 292 293 void pop_front() { Insts.pop_front(); } 294 void pop_back() { Insts.pop_back(); } 295 void push_back(MachineInstr *MI) { Insts.push_back(MI); } 296 template<typename IT> 297 void insert(iterator I, IT S, IT E) { Insts.insert(I, S, E); } 298 iterator insert(iterator I, MachineInstr *M) { return Insts.insert(I, M); } 299 300 // erase - Remove the specified element or range from the instruction list. 301 // These functions delete any instructions removed. 302 // 303 iterator erase(iterator I) { return Insts.erase(I); } 304 iterator erase(iterator I, iterator E) { return Insts.erase(I, E); } 305 MachineInstr *remove(MachineInstr *I) { return Insts.remove(I); } 306 void clear() { Insts.clear(); } 307 308 /// splice - Take an instruction from MBB 'Other' at the position From, 309 /// and insert it into this MBB right before 'where'. 310 void splice(iterator where, MachineBasicBlock *Other, iterator From) { 311 Insts.splice(where, Other->Insts, From); 312 } 313 314 /// splice - Take a block of instructions from MBB 'Other' in the range [From, 315 /// To), and insert them into this MBB right before 'where'. 316 void splice(iterator where, MachineBasicBlock *Other, iterator From, 317 iterator To) { 318 Insts.splice(where, Other->Insts, From, To); 319 } 320 321 /// removeFromParent - This method unlinks 'this' from the containing 322 /// function, and returns it, but does not delete it. 323 MachineBasicBlock *removeFromParent(); 324 325 /// eraseFromParent - This method unlinks 'this' from the containing 326 /// function and deletes it. 327 void eraseFromParent(); 328 329 /// ReplaceUsesOfBlockWith - Given a machine basic block that branched to 330 /// 'Old', change the code and CFG so that it branches to 'New' instead. 331 void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New); 332 333 /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in 334 /// the CFG to be inserted. If we have proven that MBB can only branch to 335 /// DestA and DestB, remove any other MBB successors from the CFG. DestA and 336 /// DestB can be null. Besides DestA and DestB, retain other edges leading 337 /// to LandingPads (currently there can be only one; we don't check or require 338 /// that here). Note it is possible that DestA and/or DestB are LandingPads. 339 bool CorrectExtraCFGEdges(MachineBasicBlock *DestA, 340 MachineBasicBlock *DestB, 341 bool isCond); 342 343 /// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping 344 /// any DBG_VALUE instructions. Return UnknownLoc if there is none. 345 DebugLoc findDebugLoc(MachineBasicBlock::iterator &MBBI); 346 347 // Debugging methods. 348 void dump() const; 349 void print(raw_ostream &OS) const; 350 351 /// getNumber - MachineBasicBlocks are uniquely numbered at the function 352 /// level, unless they're not in a MachineFunction yet, in which case this 353 /// will return -1. 354 /// 355 int getNumber() const { return Number; } 356 void setNumber(int N) { Number = N; } 357 358 /// getSymbol - Return the MCSymbol for this basic block. 359 /// 360 MCSymbol *getSymbol() const; 361 362private: // Methods used to maintain doubly linked list of blocks... 363 friend struct ilist_traits<MachineBasicBlock>; 364 365 // Machine-CFG mutators 366 367 /// addPredecessor - Remove pred as a predecessor of this MachineBasicBlock. 368 /// Don't do this unless you know what you're doing, because it doesn't 369 /// update pred's successors list. Use pred->addSuccessor instead. 370 /// 371 void addPredecessor(MachineBasicBlock *pred); 372 373 /// removePredecessor - Remove pred as a predecessor of this 374 /// MachineBasicBlock. Don't do this unless you know what you're 375 /// doing, because it doesn't update pred's successors list. Use 376 /// pred->removeSuccessor instead. 377 /// 378 void removePredecessor(MachineBasicBlock *pred); 379}; 380 381raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB); 382 383void WriteAsOperand(raw_ostream &, const MachineBasicBlock*, bool t); 384 385//===--------------------------------------------------------------------===// 386// GraphTraits specializations for machine basic block graphs (machine-CFGs) 387//===--------------------------------------------------------------------===// 388 389// Provide specializations of GraphTraits to be able to treat a 390// MachineFunction as a graph of MachineBasicBlocks... 391// 392 393template <> struct GraphTraits<MachineBasicBlock *> { 394 typedef MachineBasicBlock NodeType; 395 typedef MachineBasicBlock::succ_iterator ChildIteratorType; 396 397 static NodeType *getEntryNode(MachineBasicBlock *BB) { return BB; } 398 static inline ChildIteratorType child_begin(NodeType *N) { 399 return N->succ_begin(); 400 } 401 static inline ChildIteratorType child_end(NodeType *N) { 402 return N->succ_end(); 403 } 404}; 405 406template <> struct GraphTraits<const MachineBasicBlock *> { 407 typedef const MachineBasicBlock NodeType; 408 typedef MachineBasicBlock::const_succ_iterator ChildIteratorType; 409 410 static NodeType *getEntryNode(const MachineBasicBlock *BB) { return BB; } 411 static inline ChildIteratorType child_begin(NodeType *N) { 412 return N->succ_begin(); 413 } 414 static inline ChildIteratorType child_end(NodeType *N) { 415 return N->succ_end(); 416 } 417}; 418 419// Provide specializations of GraphTraits to be able to treat a 420// MachineFunction as a graph of MachineBasicBlocks... and to walk it 421// in inverse order. Inverse order for a function is considered 422// to be when traversing the predecessor edges of a MBB 423// instead of the successor edges. 424// 425template <> struct GraphTraits<Inverse<MachineBasicBlock*> > { 426 typedef MachineBasicBlock NodeType; 427 typedef MachineBasicBlock::pred_iterator ChildIteratorType; 428 static NodeType *getEntryNode(Inverse<MachineBasicBlock *> G) { 429 return G.Graph; 430 } 431 static inline ChildIteratorType child_begin(NodeType *N) { 432 return N->pred_begin(); 433 } 434 static inline ChildIteratorType child_end(NodeType *N) { 435 return N->pred_end(); 436 } 437}; 438 439template <> struct GraphTraits<Inverse<const MachineBasicBlock*> > { 440 typedef const MachineBasicBlock NodeType; 441 typedef MachineBasicBlock::const_pred_iterator ChildIteratorType; 442 static NodeType *getEntryNode(Inverse<const MachineBasicBlock*> G) { 443 return G.Graph; 444 } 445 static inline ChildIteratorType child_begin(NodeType *N) { 446 return N->pred_begin(); 447 } 448 static inline ChildIteratorType child_end(NodeType *N) { 449 return N->pred_end(); 450 } 451}; 452 453} // End llvm namespace 454 455#endif 456