MachineBasicBlock.h revision 4f28c1c71450c711e96aa283de53739d8b4504cd
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 SlotIndexes; 27class StringRef; 28class raw_ostream; 29 30template <> 31struct ilist_traits<MachineInstr> : public ilist_default_traits<MachineInstr> { 32private: 33 mutable ilist_half_node<MachineInstr> Sentinel; 34 35 // this is only set by the MachineBasicBlock owning the LiveList 36 friend class MachineBasicBlock; 37 MachineBasicBlock* Parent; 38 39public: 40 MachineInstr *createSentinel() const { 41 return static_cast<MachineInstr*>(&Sentinel); 42 } 43 void destroySentinel(MachineInstr *) const {} 44 45 MachineInstr *provideInitialHead() const { return createSentinel(); } 46 MachineInstr *ensureHead(MachineInstr*) const { return createSentinel(); } 47 static void noteHead(MachineInstr*, MachineInstr*) {} 48 49 void addNodeToList(MachineInstr* N); 50 void removeNodeFromList(MachineInstr* N); 51 void transferNodesFromList(ilist_traits &SrcTraits, 52 ilist_iterator<MachineInstr> first, 53 ilist_iterator<MachineInstr> last); 54 void deleteNode(MachineInstr *N); 55private: 56 void createNode(const MachineInstr &); 57}; 58 59class MachineBasicBlock : public ilist_node<MachineBasicBlock> { 60 typedef ilist<MachineInstr> Instructions; 61 Instructions Insts; 62 const BasicBlock *BB; 63 int Number; 64 MachineFunction *xParent; 65 66 /// Predecessors/Successors - Keep track of the predecessor / successor 67 /// basicblocks. 68 std::vector<MachineBasicBlock *> Predecessors; 69 std::vector<MachineBasicBlock *> Successors; 70 71 /// LiveIns - Keep track of the physical registers that are livein of 72 /// the basicblock. 73 std::vector<unsigned> LiveIns; 74 75 /// Alignment - Alignment of the basic block. Zero if the basic block does 76 /// not need to be aligned. 77 unsigned Alignment; 78 79 /// IsLandingPad - Indicate that this basic block is entered via an 80 /// exception handler. 81 bool IsLandingPad; 82 83 /// AddressTaken - Indicate that this basic block is potentially the 84 /// target of an indirect branch. 85 bool AddressTaken; 86 87 // Intrusive list support 88 MachineBasicBlock() {} 89 90 explicit MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb); 91 92 ~MachineBasicBlock(); 93 94 // MachineBasicBlocks are allocated and owned by MachineFunction. 95 friend class MachineFunction; 96 97public: 98 /// getBasicBlock - Return the LLVM basic block that this instance 99 /// corresponded to originally. Note that this may be NULL if this instance 100 /// does not correspond directly to an LLVM basic block. 101 /// 102 const BasicBlock *getBasicBlock() const { return BB; } 103 104 /// getName - Return the name of the corresponding LLVM basic block, or 105 /// "(null)". 106 StringRef getName() const; 107 108 /// hasAddressTaken - Test whether this block is potentially the target 109 /// of an indirect branch. 110 bool hasAddressTaken() const { return AddressTaken; } 111 112 /// setHasAddressTaken - Set this block to reflect that it potentially 113 /// is the target of an indirect branch. 114 void setHasAddressTaken() { AddressTaken = true; } 115 116 /// getParent - Return the MachineFunction containing this basic block. 117 /// 118 const MachineFunction *getParent() const { return xParent; } 119 MachineFunction *getParent() { return xParent; } 120 121 typedef Instructions::iterator iterator; 122 typedef Instructions::const_iterator const_iterator; 123 typedef std::reverse_iterator<const_iterator> const_reverse_iterator; 124 typedef std::reverse_iterator<iterator> reverse_iterator; 125 126 unsigned size() const { return (unsigned)Insts.size(); } 127 bool empty() const { return Insts.empty(); } 128 129 MachineInstr& front() { return Insts.front(); } 130 MachineInstr& back() { return Insts.back(); } 131 const MachineInstr& front() const { return Insts.front(); } 132 const MachineInstr& back() const { return Insts.back(); } 133 134 iterator begin() { return Insts.begin(); } 135 const_iterator begin() const { return Insts.begin(); } 136 iterator end() { return Insts.end(); } 137 const_iterator end() const { return Insts.end(); } 138 reverse_iterator rbegin() { return Insts.rbegin(); } 139 const_reverse_iterator rbegin() const { return Insts.rbegin(); } 140 reverse_iterator rend () { return Insts.rend(); } 141 const_reverse_iterator rend () const { return Insts.rend(); } 142 143 // Machine-CFG iterators 144 typedef std::vector<MachineBasicBlock *>::iterator pred_iterator; 145 typedef std::vector<MachineBasicBlock *>::const_iterator const_pred_iterator; 146 typedef std::vector<MachineBasicBlock *>::iterator succ_iterator; 147 typedef std::vector<MachineBasicBlock *>::const_iterator const_succ_iterator; 148 typedef std::vector<MachineBasicBlock *>::reverse_iterator 149 pred_reverse_iterator; 150 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator 151 const_pred_reverse_iterator; 152 typedef std::vector<MachineBasicBlock *>::reverse_iterator 153 succ_reverse_iterator; 154 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator 155 const_succ_reverse_iterator; 156 157 pred_iterator pred_begin() { return Predecessors.begin(); } 158 const_pred_iterator pred_begin() const { return Predecessors.begin(); } 159 pred_iterator pred_end() { return Predecessors.end(); } 160 const_pred_iterator pred_end() const { return Predecessors.end(); } 161 pred_reverse_iterator pred_rbegin() 162 { return Predecessors.rbegin();} 163 const_pred_reverse_iterator pred_rbegin() const 164 { return Predecessors.rbegin();} 165 pred_reverse_iterator pred_rend() 166 { return Predecessors.rend(); } 167 const_pred_reverse_iterator pred_rend() const 168 { return Predecessors.rend(); } 169 unsigned pred_size() const { 170 return (unsigned)Predecessors.size(); 171 } 172 bool pred_empty() const { return Predecessors.empty(); } 173 succ_iterator succ_begin() { return Successors.begin(); } 174 const_succ_iterator succ_begin() const { return Successors.begin(); } 175 succ_iterator succ_end() { return Successors.end(); } 176 const_succ_iterator succ_end() const { return Successors.end(); } 177 succ_reverse_iterator succ_rbegin() 178 { return Successors.rbegin(); } 179 const_succ_reverse_iterator succ_rbegin() const 180 { return Successors.rbegin(); } 181 succ_reverse_iterator succ_rend() 182 { return Successors.rend(); } 183 const_succ_reverse_iterator succ_rend() const 184 { return Successors.rend(); } 185 unsigned succ_size() const { 186 return (unsigned)Successors.size(); 187 } 188 bool succ_empty() const { return Successors.empty(); } 189 190 // LiveIn management methods. 191 192 /// addLiveIn - Add the specified register as a live in. Note that it 193 /// is an error to add the same register to the same set more than once. 194 void addLiveIn(unsigned Reg) { LiveIns.push_back(Reg); } 195 196 /// removeLiveIn - Remove the specified register from the live in set. 197 /// 198 void removeLiveIn(unsigned Reg); 199 200 /// isLiveIn - Return true if the specified register is in the live in set. 201 /// 202 bool isLiveIn(unsigned Reg) const; 203 204 // Iteration support for live in sets. These sets are kept in sorted 205 // order by their register number. 206 typedef std::vector<unsigned>::const_iterator livein_iterator; 207 livein_iterator livein_begin() const { return LiveIns.begin(); } 208 livein_iterator livein_end() const { return LiveIns.end(); } 209 bool livein_empty() const { return LiveIns.empty(); } 210 211 /// getAlignment - Return alignment of the basic block. 212 /// 213 unsigned getAlignment() const { return Alignment; } 214 215 /// setAlignment - Set alignment of the basic block. 216 /// 217 void setAlignment(unsigned Align) { Alignment = Align; } 218 219 /// isLandingPad - Returns true if the block is a landing pad. That is 220 /// this basic block is entered via an exception handler. 221 bool isLandingPad() const { return IsLandingPad; } 222 223 /// setIsLandingPad - Indicates the block is a landing pad. That is 224 /// this basic block is entered via an exception handler. 225 void setIsLandingPad() { IsLandingPad = true; } 226 227 // Code Layout methods. 228 229 /// moveBefore/moveAfter - move 'this' block before or after the specified 230 /// block. This only moves the block, it does not modify the CFG or adjust 231 /// potential fall-throughs at the end of the block. 232 void moveBefore(MachineBasicBlock *NewAfter); 233 void moveAfter(MachineBasicBlock *NewBefore); 234 235 /// updateTerminator - Update the terminator instructions in block to account 236 /// for changes to the layout. If the block previously used a fallthrough, 237 /// it may now need a branch, and if it previously used branching it may now 238 /// be able to use a fallthrough. 239 void updateTerminator(); 240 241 // Machine-CFG mutators 242 243 /// addSuccessor - Add succ as a successor of this MachineBasicBlock. 244 /// The Predecessors list of succ is automatically updated. 245 /// 246 void addSuccessor(MachineBasicBlock *succ); 247 248 /// removeSuccessor - Remove successor from the successors list of this 249 /// MachineBasicBlock. The Predecessors list of succ is automatically updated. 250 /// 251 void removeSuccessor(MachineBasicBlock *succ); 252 253 /// removeSuccessor - Remove specified successor from the successors list of 254 /// this MachineBasicBlock. The Predecessors list of succ is automatically 255 /// updated. Return the iterator to the element after the one removed. 256 /// 257 succ_iterator removeSuccessor(succ_iterator I); 258 259 /// transferSuccessors - Transfers all the successors from MBB to this 260 /// machine basic block (i.e., copies all the successors fromMBB and 261 /// remove all the successors from fromMBB). 262 void transferSuccessors(MachineBasicBlock *fromMBB); 263 264 /// transferSuccessorsAndUpdatePHIs - Transfers all the successors, as 265 /// in transferSuccessors, and update PHI operands in the successor blocks 266 /// which refer to fromMBB to refer to this. 267 void transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB); 268 269 /// isSuccessor - Return true if the specified MBB is a successor of this 270 /// block. 271 bool isSuccessor(const MachineBasicBlock *MBB) const; 272 273 /// isLayoutSuccessor - Return true if the specified MBB will be emitted 274 /// immediately after this block, such that if this block exits by 275 /// falling through, control will transfer to the specified MBB. Note 276 /// that MBB need not be a successor at all, for example if this block 277 /// ends with an unconditional branch to some other block. 278 bool isLayoutSuccessor(const MachineBasicBlock *MBB) const; 279 280 /// canFallThrough - Return true if the block can implicitly transfer 281 /// control to the block after it by falling off the end of it. This should 282 /// return false if it can reach the block after it, but it uses an explicit 283 /// branch to do so (e.g., a table jump). True is a conservative answer. 284 bool canFallThrough(); 285 286 /// Returns a pointer to the first instructon in this block that is not a 287 /// PHINode instruction. When adding instruction to the beginning of the 288 /// basic block, they should be added before the returned value, not before 289 /// the first instruction, which might be PHI. 290 /// Returns end() is there's no non-PHI instruction. 291 iterator getFirstNonPHI(); 292 293 /// SkipPHIsAndLabels - Return the first instruction in MBB after I that is 294 /// not a PHI or a label. This is the correct point to insert copies at the 295 /// beginning of a basic block. 296 iterator SkipPHIsAndLabels(iterator I); 297 298 /// getFirstTerminator - returns an iterator to the first terminator 299 /// instruction of this basic block. If a terminator does not exist, 300 /// it returns end() 301 iterator getFirstTerminator(); 302 303 /// getLastNonDebugInstr - returns an iterator to the last non-debug 304 /// instruction in the basic block, or end() 305 iterator getLastNonDebugInstr(); 306 307 /// SplitCriticalEdge - Split the critical edge from this block to the 308 /// given successor block, and return the newly created block, or null 309 /// if splitting is not possible. 310 /// 311 /// This function updates LiveVariables, MachineDominatorTree, and 312 /// MachineLoopInfo, as applicable. 313 MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P); 314 315 void pop_front() { Insts.pop_front(); } 316 void pop_back() { Insts.pop_back(); } 317 void push_back(MachineInstr *MI) { Insts.push_back(MI); } 318 template<typename IT> 319 void insert(iterator I, IT S, IT E) { Insts.insert(I, S, E); } 320 iterator insert(iterator I, MachineInstr *M) { return Insts.insert(I, M); } 321 iterator insertAfter(iterator I, MachineInstr *M) { 322 return Insts.insertAfter(I, M); 323 } 324 325 // erase - Remove the specified element or range from the instruction list. 326 // These functions delete any instructions removed. 327 // 328 iterator erase(iterator I) { return Insts.erase(I); } 329 iterator erase(iterator I, iterator E) { return Insts.erase(I, E); } 330 MachineInstr *remove(MachineInstr *I) { return Insts.remove(I); } 331 void clear() { Insts.clear(); } 332 333 /// splice - Take an instruction from MBB 'Other' at the position From, 334 /// and insert it into this MBB right before 'where'. 335 void splice(iterator where, MachineBasicBlock *Other, iterator From) { 336 Insts.splice(where, Other->Insts, From); 337 } 338 339 /// splice - Take a block of instructions from MBB 'Other' in the range [From, 340 /// To), and insert them into this MBB right before 'where'. 341 void splice(iterator where, MachineBasicBlock *Other, iterator From, 342 iterator To) { 343 Insts.splice(where, Other->Insts, From, To); 344 } 345 346 /// removeFromParent - This method unlinks 'this' from the containing 347 /// function, and returns it, but does not delete it. 348 MachineBasicBlock *removeFromParent(); 349 350 /// eraseFromParent - This method unlinks 'this' from the containing 351 /// function and deletes it. 352 void eraseFromParent(); 353 354 /// ReplaceUsesOfBlockWith - Given a machine basic block that branched to 355 /// 'Old', change the code and CFG so that it branches to 'New' instead. 356 void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New); 357 358 /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in 359 /// the CFG to be inserted. If we have proven that MBB can only branch to 360 /// DestA and DestB, remove any other MBB successors from the CFG. DestA and 361 /// DestB can be null. Besides DestA and DestB, retain other edges leading 362 /// to LandingPads (currently there can be only one; we don't check or require 363 /// that here). Note it is possible that DestA and/or DestB are LandingPads. 364 bool CorrectExtraCFGEdges(MachineBasicBlock *DestA, 365 MachineBasicBlock *DestB, 366 bool isCond); 367 368 /// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping 369 /// any DBG_VALUE instructions. Return UnknownLoc if there is none. 370 DebugLoc findDebugLoc(MachineBasicBlock::iterator &MBBI); 371 372 // Debugging methods. 373 void dump() const; 374 void print(raw_ostream &OS, SlotIndexes* = 0) const; 375 376 /// getNumber - MachineBasicBlocks are uniquely numbered at the function 377 /// level, unless they're not in a MachineFunction yet, in which case this 378 /// will return -1. 379 /// 380 int getNumber() const { return Number; } 381 void setNumber(int N) { Number = N; } 382 383 /// getSymbol - Return the MCSymbol for this basic block. 384 /// 385 MCSymbol *getSymbol() const; 386 387private: // Methods used to maintain doubly linked list of blocks... 388 friend struct ilist_traits<MachineBasicBlock>; 389 390 // Machine-CFG mutators 391 392 /// addPredecessor - Remove pred as a predecessor of this MachineBasicBlock. 393 /// Don't do this unless you know what you're doing, because it doesn't 394 /// update pred's successors list. Use pred->addSuccessor instead. 395 /// 396 void addPredecessor(MachineBasicBlock *pred); 397 398 /// removePredecessor - Remove pred as a predecessor of this 399 /// MachineBasicBlock. Don't do this unless you know what you're 400 /// doing, because it doesn't update pred's successors list. Use 401 /// pred->removeSuccessor instead. 402 /// 403 void removePredecessor(MachineBasicBlock *pred); 404}; 405 406raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB); 407 408void WriteAsOperand(raw_ostream &, const MachineBasicBlock*, bool t); 409 410//===--------------------------------------------------------------------===// 411// GraphTraits specializations for machine basic block graphs (machine-CFGs) 412//===--------------------------------------------------------------------===// 413 414// Provide specializations of GraphTraits to be able to treat a 415// MachineFunction as a graph of MachineBasicBlocks... 416// 417 418template <> struct GraphTraits<MachineBasicBlock *> { 419 typedef MachineBasicBlock NodeType; 420 typedef MachineBasicBlock::succ_iterator ChildIteratorType; 421 422 static NodeType *getEntryNode(MachineBasicBlock *BB) { return BB; } 423 static inline ChildIteratorType child_begin(NodeType *N) { 424 return N->succ_begin(); 425 } 426 static inline ChildIteratorType child_end(NodeType *N) { 427 return N->succ_end(); 428 } 429}; 430 431template <> struct GraphTraits<const MachineBasicBlock *> { 432 typedef const MachineBasicBlock NodeType; 433 typedef MachineBasicBlock::const_succ_iterator ChildIteratorType; 434 435 static NodeType *getEntryNode(const MachineBasicBlock *BB) { return BB; } 436 static inline ChildIteratorType child_begin(NodeType *N) { 437 return N->succ_begin(); 438 } 439 static inline ChildIteratorType child_end(NodeType *N) { 440 return N->succ_end(); 441 } 442}; 443 444// Provide specializations of GraphTraits to be able to treat a 445// MachineFunction as a graph of MachineBasicBlocks... and to walk it 446// in inverse order. Inverse order for a function is considered 447// to be when traversing the predecessor edges of a MBB 448// instead of the successor edges. 449// 450template <> struct GraphTraits<Inverse<MachineBasicBlock*> > { 451 typedef MachineBasicBlock NodeType; 452 typedef MachineBasicBlock::pred_iterator ChildIteratorType; 453 static NodeType *getEntryNode(Inverse<MachineBasicBlock *> G) { 454 return G.Graph; 455 } 456 static inline ChildIteratorType child_begin(NodeType *N) { 457 return N->pred_begin(); 458 } 459 static inline ChildIteratorType child_end(NodeType *N) { 460 return N->pred_end(); 461 } 462}; 463 464template <> struct GraphTraits<Inverse<const MachineBasicBlock*> > { 465 typedef const MachineBasicBlock NodeType; 466 typedef MachineBasicBlock::const_pred_iterator ChildIteratorType; 467 static NodeType *getEntryNode(Inverse<const MachineBasicBlock*> G) { 468 return G.Graph; 469 } 470 static inline ChildIteratorType child_begin(NodeType *N) { 471 return N->pred_begin(); 472 } 473 static inline ChildIteratorType child_end(NodeType *N) { 474 return N->pred_end(); 475 } 476}; 477 478} // End llvm namespace 479 480#endif 481