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 #include "llvm/Support/DataTypes.h" 20 #include <functional> 21 22 namespace llvm { 23 24 class Pass; 25 class BasicBlock; 26 class MachineFunction; 27 class MCSymbol; 28 class SlotIndexes; 29 class StringRef; 30 class raw_ostream; 31 class MachineBranchProbabilityInfo; 32 33 template <> 34 struct ilist_traits<MachineInstr> : public ilist_default_traits<MachineInstr> { 35 private: 36 mutable ilist_half_node<MachineInstr> Sentinel; 37 38 // this is only set by the MachineBasicBlock owning the LiveList 39 friend class MachineBasicBlock; 40 MachineBasicBlock* Parent; 41 42 public: 43 MachineInstr *createSentinel() const { 44 return static_cast<MachineInstr*>(&Sentinel); 45 } 46 void destroySentinel(MachineInstr *) const {} 47 48 MachineInstr *provideInitialHead() const { return createSentinel(); } 49 MachineInstr *ensureHead(MachineInstr*) const { return createSentinel(); } 50 static void noteHead(MachineInstr*, MachineInstr*) {} 51 52 void addNodeToList(MachineInstr* N); 53 void removeNodeFromList(MachineInstr* N); 54 void transferNodesFromList(ilist_traits &SrcTraits, 55 ilist_iterator<MachineInstr> first, 56 ilist_iterator<MachineInstr> last); 57 void deleteNode(MachineInstr *N); 58 private: 59 void createNode(const MachineInstr &); 60 }; 61 62 class MachineBasicBlock : public ilist_node<MachineBasicBlock> { 63 typedef ilist<MachineInstr> Instructions; 64 Instructions Insts; 65 const BasicBlock *BB; 66 int Number; 67 MachineFunction *xParent; 68 69 /// Predecessors/Successors - Keep track of the predecessor / successor 70 /// basicblocks. 71 std::vector<MachineBasicBlock *> Predecessors; 72 std::vector<MachineBasicBlock *> Successors; 73 74 75 /// Weights - Keep track of the weights to the successors. This vector 76 /// has the same order as Successors, or it is empty if we don't use it 77 /// (disable optimization). 78 std::vector<uint32_t> Weights; 79 typedef std::vector<uint32_t>::iterator weight_iterator; 80 81 /// LiveIns - Keep track of the physical registers that are livein of 82 /// the basicblock. 83 std::vector<unsigned> LiveIns; 84 85 /// Alignment - Alignment of the basic block. Zero if the basic block does 86 /// not need to be aligned. 87 unsigned Alignment; 88 89 /// IsLandingPad - Indicate that this basic block is entered via an 90 /// exception handler. 91 bool IsLandingPad; 92 93 /// AddressTaken - Indicate that this basic block is potentially the 94 /// target of an indirect branch. 95 bool AddressTaken; 96 97 // Intrusive list support 98 MachineBasicBlock() {} 99 100 explicit MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb); 101 102 ~MachineBasicBlock(); 103 104 // MachineBasicBlocks are allocated and owned by MachineFunction. 105 friend class MachineFunction; 106 107 public: 108 /// getBasicBlock - Return the LLVM basic block that this instance 109 /// corresponded to originally. Note that this may be NULL if this instance 110 /// does not correspond directly to an LLVM basic block. 111 /// 112 const BasicBlock *getBasicBlock() const { return BB; } 113 114 /// getName - Return the name of the corresponding LLVM basic block, or 115 /// "(null)". 116 StringRef getName() const; 117 118 /// hasAddressTaken - Test whether this block is potentially the target 119 /// of an indirect branch. 120 bool hasAddressTaken() const { return AddressTaken; } 121 122 /// setHasAddressTaken - Set this block to reflect that it potentially 123 /// is the target of an indirect branch. 124 void setHasAddressTaken() { AddressTaken = true; } 125 126 /// getParent - Return the MachineFunction containing this basic block. 127 /// 128 const MachineFunction *getParent() const { return xParent; } 129 MachineFunction *getParent() { return xParent; } 130 131 typedef Instructions::iterator iterator; 132 typedef Instructions::const_iterator const_iterator; 133 typedef std::reverse_iterator<const_iterator> const_reverse_iterator; 134 typedef std::reverse_iterator<iterator> reverse_iterator; 135 136 unsigned size() const { return (unsigned)Insts.size(); } 137 bool empty() const { return Insts.empty(); } 138 139 MachineInstr& front() { return Insts.front(); } 140 MachineInstr& back() { return Insts.back(); } 141 const MachineInstr& front() const { return Insts.front(); } 142 const MachineInstr& back() const { return Insts.back(); } 143 144 iterator begin() { return Insts.begin(); } 145 const_iterator begin() const { return Insts.begin(); } 146 iterator end() { return Insts.end(); } 147 const_iterator end() const { return Insts.end(); } 148 reverse_iterator rbegin() { return Insts.rbegin(); } 149 const_reverse_iterator rbegin() const { return Insts.rbegin(); } 150 reverse_iterator rend () { return Insts.rend(); } 151 const_reverse_iterator rend () const { return Insts.rend(); } 152 153 // Machine-CFG iterators 154 typedef std::vector<MachineBasicBlock *>::iterator pred_iterator; 155 typedef std::vector<MachineBasicBlock *>::const_iterator const_pred_iterator; 156 typedef std::vector<MachineBasicBlock *>::iterator succ_iterator; 157 typedef std::vector<MachineBasicBlock *>::const_iterator const_succ_iterator; 158 typedef std::vector<MachineBasicBlock *>::reverse_iterator 159 pred_reverse_iterator; 160 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator 161 const_pred_reverse_iterator; 162 typedef std::vector<MachineBasicBlock *>::reverse_iterator 163 succ_reverse_iterator; 164 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator 165 const_succ_reverse_iterator; 166 167 pred_iterator pred_begin() { return Predecessors.begin(); } 168 const_pred_iterator pred_begin() const { return Predecessors.begin(); } 169 pred_iterator pred_end() { return Predecessors.end(); } 170 const_pred_iterator pred_end() const { return Predecessors.end(); } 171 pred_reverse_iterator pred_rbegin() 172 { return Predecessors.rbegin();} 173 const_pred_reverse_iterator pred_rbegin() const 174 { return Predecessors.rbegin();} 175 pred_reverse_iterator pred_rend() 176 { return Predecessors.rend(); } 177 const_pred_reverse_iterator pred_rend() const 178 { return Predecessors.rend(); } 179 unsigned pred_size() const { 180 return (unsigned)Predecessors.size(); 181 } 182 bool pred_empty() const { return Predecessors.empty(); } 183 succ_iterator succ_begin() { return Successors.begin(); } 184 const_succ_iterator succ_begin() const { return Successors.begin(); } 185 succ_iterator succ_end() { return Successors.end(); } 186 const_succ_iterator succ_end() const { return Successors.end(); } 187 succ_reverse_iterator succ_rbegin() 188 { return Successors.rbegin(); } 189 const_succ_reverse_iterator succ_rbegin() const 190 { return Successors.rbegin(); } 191 succ_reverse_iterator succ_rend() 192 { return Successors.rend(); } 193 const_succ_reverse_iterator succ_rend() const 194 { return Successors.rend(); } 195 unsigned succ_size() const { 196 return (unsigned)Successors.size(); 197 } 198 bool succ_empty() const { return Successors.empty(); } 199 200 // LiveIn management methods. 201 202 /// addLiveIn - Add the specified register as a live in. Note that it 203 /// is an error to add the same register to the same set more than once. 204 void addLiveIn(unsigned Reg) { LiveIns.push_back(Reg); } 205 206 /// removeLiveIn - Remove the specified register from the live in set. 207 /// 208 void removeLiveIn(unsigned Reg); 209 210 /// isLiveIn - Return true if the specified register is in the live in set. 211 /// 212 bool isLiveIn(unsigned Reg) const; 213 214 // Iteration support for live in sets. These sets are kept in sorted 215 // order by their register number. 216 typedef std::vector<unsigned>::const_iterator livein_iterator; 217 livein_iterator livein_begin() const { return LiveIns.begin(); } 218 livein_iterator livein_end() const { return LiveIns.end(); } 219 bool livein_empty() const { return LiveIns.empty(); } 220 221 /// getAlignment - Return alignment of the basic block. 222 /// 223 unsigned getAlignment() const { return Alignment; } 224 225 /// setAlignment - Set alignment of the basic block. 226 /// 227 void setAlignment(unsigned Align) { Alignment = Align; } 228 229 /// isLandingPad - Returns true if the block is a landing pad. That is 230 /// this basic block is entered via an exception handler. 231 bool isLandingPad() const { return IsLandingPad; } 232 233 /// setIsLandingPad - Indicates the block is a landing pad. That is 234 /// this basic block is entered via an exception handler. 235 void setIsLandingPad(bool V = true) { IsLandingPad = V; } 236 237 /// getLandingPadSuccessor - If this block has a successor that is a landing 238 /// pad, return it. Otherwise return NULL. 239 const MachineBasicBlock *getLandingPadSuccessor() const; 240 241 // Code Layout methods. 242 243 /// moveBefore/moveAfter - move 'this' block before or after the specified 244 /// block. This only moves the block, it does not modify the CFG or adjust 245 /// potential fall-throughs at the end of the block. 246 void moveBefore(MachineBasicBlock *NewAfter); 247 void moveAfter(MachineBasicBlock *NewBefore); 248 249 /// updateTerminator - Update the terminator instructions in block to account 250 /// for changes to the layout. If the block previously used a fallthrough, 251 /// it may now need a branch, and if it previously used branching it may now 252 /// be able to use a fallthrough. 253 void updateTerminator(); 254 255 // Machine-CFG mutators 256 257 /// addSuccessor - Add succ as a successor of this MachineBasicBlock. 258 /// The Predecessors list of succ is automatically updated. WEIGHT 259 /// parameter is stored in Weights list and it may be used by 260 /// MachineBranchProbabilityInfo analysis to calculate branch probability. 261 /// 262 void addSuccessor(MachineBasicBlock *succ, uint32_t weight = 0); 263 264 /// removeSuccessor - Remove successor from the successors list of this 265 /// MachineBasicBlock. The Predecessors list of succ is automatically updated. 266 /// 267 void removeSuccessor(MachineBasicBlock *succ); 268 269 /// removeSuccessor - Remove specified successor from the successors list of 270 /// this MachineBasicBlock. The Predecessors list of succ is automatically 271 /// updated. Return the iterator to the element after the one removed. 272 /// 273 succ_iterator removeSuccessor(succ_iterator I); 274 275 /// replaceSuccessor - Replace successor OLD with NEW and update weight info. 276 /// 277 void replaceSuccessor(MachineBasicBlock *Old, MachineBasicBlock *New); 278 279 280 /// transferSuccessors - Transfers all the successors from MBB to this 281 /// machine basic block (i.e., copies all the successors fromMBB and 282 /// remove all the successors from fromMBB). 283 void transferSuccessors(MachineBasicBlock *fromMBB); 284 285 /// transferSuccessorsAndUpdatePHIs - Transfers all the successors, as 286 /// in transferSuccessors, and update PHI operands in the successor blocks 287 /// which refer to fromMBB to refer to this. 288 void transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB); 289 290 /// isSuccessor - Return true if the specified MBB is a successor of this 291 /// block. 292 bool isSuccessor(const MachineBasicBlock *MBB) const; 293 294 /// isLayoutSuccessor - Return true if the specified MBB will be emitted 295 /// immediately after this block, such that if this block exits by 296 /// falling through, control will transfer to the specified MBB. Note 297 /// that MBB need not be a successor at all, for example if this block 298 /// ends with an unconditional branch to some other block. 299 bool isLayoutSuccessor(const MachineBasicBlock *MBB) const; 300 301 /// canFallThrough - Return true if the block can implicitly transfer 302 /// control to the block after it by falling off the end of it. This should 303 /// return false if it can reach the block after it, but it uses an explicit 304 /// branch to do so (e.g., a table jump). True is a conservative answer. 305 bool canFallThrough(); 306 307 /// Returns a pointer to the first instructon in this block that is not a 308 /// PHINode instruction. When adding instruction to the beginning of the 309 /// basic block, they should be added before the returned value, not before 310 /// the first instruction, which might be PHI. 311 /// Returns end() is there's no non-PHI instruction. 312 iterator getFirstNonPHI(); 313 314 /// SkipPHIsAndLabels - Return the first instruction in MBB after I that is 315 /// not a PHI or a label. This is the correct point to insert copies at the 316 /// beginning of a basic block. 317 iterator SkipPHIsAndLabels(iterator I); 318 319 /// getFirstTerminator - returns an iterator to the first terminator 320 /// instruction of this basic block. If a terminator does not exist, 321 /// it returns end() 322 iterator getFirstTerminator(); 323 324 const_iterator getFirstTerminator() const { 325 return const_cast<MachineBasicBlock*>(this)->getFirstTerminator(); 326 } 327 328 /// getLastNonDebugInstr - returns an iterator to the last non-debug 329 /// instruction in the basic block, or end() 330 iterator getLastNonDebugInstr(); 331 332 const_iterator getLastNonDebugInstr() const { 333 return const_cast<MachineBasicBlock*>(this)->getLastNonDebugInstr(); 334 } 335 336 /// SplitCriticalEdge - Split the critical edge from this block to the 337 /// given successor block, and return the newly created block, or null 338 /// if splitting is not possible. 339 /// 340 /// This function updates LiveVariables, MachineDominatorTree, and 341 /// MachineLoopInfo, as applicable. 342 MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P); 343 344 void pop_front() { Insts.pop_front(); } 345 void pop_back() { Insts.pop_back(); } 346 void push_back(MachineInstr *MI) { Insts.push_back(MI); } 347 template<typename IT> 348 void insert(iterator I, IT S, IT E) { Insts.insert(I, S, E); } 349 iterator insert(iterator I, MachineInstr *M) { return Insts.insert(I, M); } 350 iterator insertAfter(iterator I, MachineInstr *M) { 351 return Insts.insertAfter(I, M); 352 } 353 354 // erase - Remove the specified element or range from the instruction list. 355 // These functions delete any instructions removed. 356 // 357 iterator erase(iterator I) { return Insts.erase(I); } 358 iterator erase(iterator I, iterator E) { return Insts.erase(I, E); } 359 MachineInstr *remove(MachineInstr *I) { return Insts.remove(I); } 360 void clear() { Insts.clear(); } 361 362 /// splice - Take an instruction from MBB 'Other' at the position From, 363 /// and insert it into this MBB right before 'where'. 364 void splice(iterator where, MachineBasicBlock *Other, iterator From) { 365 Insts.splice(where, Other->Insts, From); 366 } 367 368 /// splice - Take a block of instructions from MBB 'Other' in the range [From, 369 /// To), and insert them into this MBB right before 'where'. 370 void splice(iterator where, MachineBasicBlock *Other, iterator From, 371 iterator To) { 372 Insts.splice(where, Other->Insts, From, To); 373 } 374 375 /// removeFromParent - This method unlinks 'this' from the containing 376 /// function, and returns it, but does not delete it. 377 MachineBasicBlock *removeFromParent(); 378 379 /// eraseFromParent - This method unlinks 'this' from the containing 380 /// function and deletes it. 381 void eraseFromParent(); 382 383 /// ReplaceUsesOfBlockWith - Given a machine basic block that branched to 384 /// 'Old', change the code and CFG so that it branches to 'New' instead. 385 void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New); 386 387 /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in 388 /// the CFG to be inserted. If we have proven that MBB can only branch to 389 /// DestA and DestB, remove any other MBB successors from the CFG. DestA and 390 /// DestB can be null. Besides DestA and DestB, retain other edges leading 391 /// to LandingPads (currently there can be only one; we don't check or require 392 /// that here). Note it is possible that DestA and/or DestB are LandingPads. 393 bool CorrectExtraCFGEdges(MachineBasicBlock *DestA, 394 MachineBasicBlock *DestB, 395 bool isCond); 396 397 /// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping 398 /// any DBG_VALUE instructions. Return UnknownLoc if there is none. 399 DebugLoc findDebugLoc(MachineBasicBlock::iterator &MBBI); 400 401 // Debugging methods. 402 void dump() const; 403 void print(raw_ostream &OS, SlotIndexes* = 0) const; 404 405 /// getNumber - MachineBasicBlocks are uniquely numbered at the function 406 /// level, unless they're not in a MachineFunction yet, in which case this 407 /// will return -1. 408 /// 409 int getNumber() const { return Number; } 410 void setNumber(int N) { Number = N; } 411 412 /// getSymbol - Return the MCSymbol for this basic block. 413 /// 414 MCSymbol *getSymbol() const; 415 416 417 private: 418 /// getWeightIterator - Return weight iterator corresponding to the I 419 /// successor iterator. 420 weight_iterator getWeightIterator(succ_iterator I); 421 422 friend class MachineBranchProbabilityInfo; 423 424 /// getSuccWeight - Return weight of the edge from this block to MBB. This 425 /// method should NOT be called directly, but by using getEdgeWeight method 426 /// from MachineBranchProbabilityInfo class. 427 uint32_t getSuccWeight(MachineBasicBlock *succ); 428 429 430 // Methods used to maintain doubly linked list of blocks... 431 friend struct ilist_traits<MachineBasicBlock>; 432 433 // Machine-CFG mutators 434 435 /// addPredecessor - Remove pred as a predecessor of this MachineBasicBlock. 436 /// Don't do this unless you know what you're doing, because it doesn't 437 /// update pred's successors list. Use pred->addSuccessor instead. 438 /// 439 void addPredecessor(MachineBasicBlock *pred); 440 441 /// removePredecessor - Remove pred as a predecessor of this 442 /// MachineBasicBlock. Don't do this unless you know what you're 443 /// doing, because it doesn't update pred's successors list. Use 444 /// pred->removeSuccessor instead. 445 /// 446 void removePredecessor(MachineBasicBlock *pred); 447 }; 448 449 raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB); 450 451 void WriteAsOperand(raw_ostream &, const MachineBasicBlock*, bool t); 452 453 // This is useful when building IndexedMaps keyed on basic block pointers. 454 struct MBB2NumberFunctor : 455 public std::unary_function<const MachineBasicBlock*, unsigned> { 456 unsigned operator()(const MachineBasicBlock *MBB) const { 457 return MBB->getNumber(); 458 } 459 }; 460 461 //===--------------------------------------------------------------------===// 462 // GraphTraits specializations for machine basic block graphs (machine-CFGs) 463 //===--------------------------------------------------------------------===// 464 465 // Provide specializations of GraphTraits to be able to treat a 466 // MachineFunction as a graph of MachineBasicBlocks... 467 // 468 469 template <> struct GraphTraits<MachineBasicBlock *> { 470 typedef MachineBasicBlock NodeType; 471 typedef MachineBasicBlock::succ_iterator ChildIteratorType; 472 473 static NodeType *getEntryNode(MachineBasicBlock *BB) { return BB; } 474 static inline ChildIteratorType child_begin(NodeType *N) { 475 return N->succ_begin(); 476 } 477 static inline ChildIteratorType child_end(NodeType *N) { 478 return N->succ_end(); 479 } 480 }; 481 482 template <> struct GraphTraits<const MachineBasicBlock *> { 483 typedef const MachineBasicBlock NodeType; 484 typedef MachineBasicBlock::const_succ_iterator ChildIteratorType; 485 486 static NodeType *getEntryNode(const MachineBasicBlock *BB) { return BB; } 487 static inline ChildIteratorType child_begin(NodeType *N) { 488 return N->succ_begin(); 489 } 490 static inline ChildIteratorType child_end(NodeType *N) { 491 return N->succ_end(); 492 } 493 }; 494 495 // Provide specializations of GraphTraits to be able to treat a 496 // MachineFunction as a graph of MachineBasicBlocks... and to walk it 497 // in inverse order. Inverse order for a function is considered 498 // to be when traversing the predecessor edges of a MBB 499 // instead of the successor edges. 500 // 501 template <> struct GraphTraits<Inverse<MachineBasicBlock*> > { 502 typedef MachineBasicBlock NodeType; 503 typedef MachineBasicBlock::pred_iterator ChildIteratorType; 504 static NodeType *getEntryNode(Inverse<MachineBasicBlock *> G) { 505 return G.Graph; 506 } 507 static inline ChildIteratorType child_begin(NodeType *N) { 508 return N->pred_begin(); 509 } 510 static inline ChildIteratorType child_end(NodeType *N) { 511 return N->pred_end(); 512 } 513 }; 514 515 template <> struct GraphTraits<Inverse<const MachineBasicBlock*> > { 516 typedef const MachineBasicBlock NodeType; 517 typedef MachineBasicBlock::const_pred_iterator ChildIteratorType; 518 static NodeType *getEntryNode(Inverse<const MachineBasicBlock*> G) { 519 return G.Graph; 520 } 521 static inline ChildIteratorType child_begin(NodeType *N) { 522 return N->pred_begin(); 523 } 524 static inline ChildIteratorType child_end(NodeType *N) { 525 return N->pred_end(); 526 } 527 }; 528 529 } // End llvm namespace 530 531 #endif 532