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/ADT/GraphTraits.h" 18 #include "llvm/CodeGen/MachineInstr.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 /// Weights - Keep track of the weights to the successors. This vector 75 /// has the same order as Successors, or it is empty if we don't use it 76 /// (disable optimization). 77 std::vector<uint32_t> Weights; 78 typedef std::vector<uint32_t>::iterator weight_iterator; 79 typedef std::vector<uint32_t>::const_iterator const_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 /// The alignment is specified as log2(bytes). 88 unsigned Alignment; 89 90 /// IsLandingPad - Indicate that this basic block is entered via an 91 /// exception handler. 92 bool IsLandingPad; 93 94 /// AddressTaken - Indicate that this basic block is potentially the 95 /// target of an indirect branch. 96 bool AddressTaken; 97 98 /// \brief since getSymbol is a relatively heavy-weight operation, the symbol 99 /// is only computed once and is cached. 100 mutable MCSymbol *CachedMCSymbol; 101 102 // Intrusive list support 103 MachineBasicBlock() {} 104 105 explicit MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb); 106 107 ~MachineBasicBlock(); 108 109 // MachineBasicBlocks are allocated and owned by MachineFunction. 110 friend class MachineFunction; 111 112 public: 113 /// getBasicBlock - Return the LLVM basic block that this instance 114 /// corresponded to originally. Note that this may be NULL if this instance 115 /// does not correspond directly to an LLVM basic block. 116 /// 117 const BasicBlock *getBasicBlock() const { return BB; } 118 119 /// getName - Return the name of the corresponding LLVM basic block, or 120 /// "(null)". 121 StringRef getName() const; 122 123 /// getFullName - Return a formatted string to identify this block and its 124 /// parent function. 125 std::string getFullName() const; 126 127 /// hasAddressTaken - Test whether this block is potentially the target 128 /// of an indirect branch. 129 bool hasAddressTaken() const { return AddressTaken; } 130 131 /// setHasAddressTaken - Set this block to reflect that it potentially 132 /// is the target of an indirect branch. 133 void setHasAddressTaken() { AddressTaken = true; } 134 135 /// getParent - Return the MachineFunction containing this basic block. 136 /// 137 const MachineFunction *getParent() const { return xParent; } 138 MachineFunction *getParent() { return xParent; } 139 140 141 /// bundle_iterator - MachineBasicBlock iterator that automatically skips over 142 /// MIs that are inside bundles (i.e. walk top level MIs only). 143 template<typename Ty, typename IterTy> 144 class bundle_iterator 145 : public std::iterator<std::bidirectional_iterator_tag, Ty, ptrdiff_t> { 146 IterTy MII; 147 148 public: 149 bundle_iterator(IterTy mii) : MII(mii) {} 150 151 bundle_iterator(Ty &mi) : MII(mi) { 152 assert(!mi.isBundledWithPred() && 153 "It's not legal to initialize bundle_iterator with a bundled MI"); 154 } 155 bundle_iterator(Ty *mi) : MII(mi) { 156 assert((!mi || !mi->isBundledWithPred()) && 157 "It's not legal to initialize bundle_iterator with a bundled MI"); 158 } 159 // Template allows conversion from const to nonconst. 160 template<class OtherTy, class OtherIterTy> 161 bundle_iterator(const bundle_iterator<OtherTy, OtherIterTy> &I) 162 : MII(I.getInstrIterator()) {} 163 bundle_iterator() : MII(nullptr) {} 164 165 Ty &operator*() const { return *MII; } 166 Ty *operator->() const { return &operator*(); } 167 168 operator Ty*() const { return MII; } 169 170 bool operator==(const bundle_iterator &x) const { 171 return MII == x.MII; 172 } 173 bool operator!=(const bundle_iterator &x) const { 174 return !operator==(x); 175 } 176 177 // Increment and decrement operators... 178 bundle_iterator &operator--() { // predecrement - Back up 179 do --MII; 180 while (MII->isBundledWithPred()); 181 return *this; 182 } 183 bundle_iterator &operator++() { // preincrement - Advance 184 while (MII->isBundledWithSucc()) 185 ++MII; 186 ++MII; 187 return *this; 188 } 189 bundle_iterator operator--(int) { // postdecrement operators... 190 bundle_iterator tmp = *this; 191 --*this; 192 return tmp; 193 } 194 bundle_iterator operator++(int) { // postincrement operators... 195 bundle_iterator tmp = *this; 196 ++*this; 197 return tmp; 198 } 199 200 IterTy getInstrIterator() const { 201 return MII; 202 } 203 }; 204 205 typedef Instructions::iterator instr_iterator; 206 typedef Instructions::const_iterator const_instr_iterator; 207 typedef std::reverse_iterator<instr_iterator> reverse_instr_iterator; 208 typedef 209 std::reverse_iterator<const_instr_iterator> const_reverse_instr_iterator; 210 211 typedef 212 bundle_iterator<MachineInstr,instr_iterator> iterator; 213 typedef 214 bundle_iterator<const MachineInstr,const_instr_iterator> const_iterator; 215 typedef std::reverse_iterator<const_iterator> const_reverse_iterator; 216 typedef std::reverse_iterator<iterator> reverse_iterator; 217 218 219 unsigned size() const { return (unsigned)Insts.size(); } 220 bool empty() const { return Insts.empty(); } 221 222 MachineInstr &instr_front() { return Insts.front(); } 223 MachineInstr &instr_back() { return Insts.back(); } 224 const MachineInstr &instr_front() const { return Insts.front(); } 225 const MachineInstr &instr_back() const { return Insts.back(); } 226 227 MachineInstr &front() { return Insts.front(); } 228 MachineInstr &back() { return *--end(); } 229 const MachineInstr &front() const { return Insts.front(); } 230 const MachineInstr &back() const { return *--end(); } 231 232 instr_iterator instr_begin() { return Insts.begin(); } 233 const_instr_iterator instr_begin() const { return Insts.begin(); } 234 instr_iterator instr_end() { return Insts.end(); } 235 const_instr_iterator instr_end() const { return Insts.end(); } 236 reverse_instr_iterator instr_rbegin() { return Insts.rbegin(); } 237 const_reverse_instr_iterator instr_rbegin() const { return Insts.rbegin(); } 238 reverse_instr_iterator instr_rend () { return Insts.rend(); } 239 const_reverse_instr_iterator instr_rend () const { return Insts.rend(); } 240 241 iterator begin() { return instr_begin(); } 242 const_iterator begin() const { return instr_begin(); } 243 iterator end () { return instr_end(); } 244 const_iterator end () const { return instr_end(); } 245 reverse_iterator rbegin() { return instr_rbegin(); } 246 const_reverse_iterator rbegin() const { return instr_rbegin(); } 247 reverse_iterator rend () { return instr_rend(); } 248 const_reverse_iterator rend () const { return instr_rend(); } 249 250 inline iterator_range<iterator> terminators() { 251 return iterator_range<iterator>(getFirstTerminator(), end()); 252 } 253 inline iterator_range<const_iterator> terminators() const { 254 return iterator_range<const_iterator>(getFirstTerminator(), end()); 255 } 256 257 // Machine-CFG iterators 258 typedef std::vector<MachineBasicBlock *>::iterator pred_iterator; 259 typedef std::vector<MachineBasicBlock *>::const_iterator const_pred_iterator; 260 typedef std::vector<MachineBasicBlock *>::iterator succ_iterator; 261 typedef std::vector<MachineBasicBlock *>::const_iterator const_succ_iterator; 262 typedef std::vector<MachineBasicBlock *>::reverse_iterator 263 pred_reverse_iterator; 264 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator 265 const_pred_reverse_iterator; 266 typedef std::vector<MachineBasicBlock *>::reverse_iterator 267 succ_reverse_iterator; 268 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator 269 const_succ_reverse_iterator; 270 pred_iterator pred_begin() { return Predecessors.begin(); } 271 const_pred_iterator pred_begin() const { return Predecessors.begin(); } 272 pred_iterator pred_end() { return Predecessors.end(); } 273 const_pred_iterator pred_end() const { return Predecessors.end(); } 274 pred_reverse_iterator pred_rbegin() 275 { return Predecessors.rbegin();} 276 const_pred_reverse_iterator pred_rbegin() const 277 { return Predecessors.rbegin();} 278 pred_reverse_iterator pred_rend() 279 { return Predecessors.rend(); } 280 const_pred_reverse_iterator pred_rend() const 281 { return Predecessors.rend(); } 282 unsigned pred_size() const { 283 return (unsigned)Predecessors.size(); 284 } 285 bool pred_empty() const { return Predecessors.empty(); } 286 succ_iterator succ_begin() { return Successors.begin(); } 287 const_succ_iterator succ_begin() const { return Successors.begin(); } 288 succ_iterator succ_end() { return Successors.end(); } 289 const_succ_iterator succ_end() const { return Successors.end(); } 290 succ_reverse_iterator succ_rbegin() 291 { return Successors.rbegin(); } 292 const_succ_reverse_iterator succ_rbegin() const 293 { return Successors.rbegin(); } 294 succ_reverse_iterator succ_rend() 295 { return Successors.rend(); } 296 const_succ_reverse_iterator succ_rend() const 297 { return Successors.rend(); } 298 unsigned succ_size() const { 299 return (unsigned)Successors.size(); 300 } 301 bool succ_empty() const { return Successors.empty(); } 302 303 inline iterator_range<pred_iterator> predecessors() { 304 return iterator_range<pred_iterator>(pred_begin(), pred_end()); 305 } 306 inline iterator_range<const_pred_iterator> predecessors() const { 307 return iterator_range<const_pred_iterator>(pred_begin(), pred_end()); 308 } 309 inline iterator_range<succ_iterator> successors() { 310 return iterator_range<succ_iterator>(succ_begin(), succ_end()); 311 } 312 inline iterator_range<const_succ_iterator> successors() const { 313 return iterator_range<const_succ_iterator>(succ_begin(), succ_end()); 314 } 315 316 // LiveIn management methods. 317 318 /// addLiveIn - Add the specified register as a live in. Note that it 319 /// is an error to add the same register to the same set more than once. 320 void addLiveIn(unsigned Reg) { LiveIns.push_back(Reg); } 321 322 /// Add PhysReg as live in to this block, and ensure that there is a copy of 323 /// PhysReg to a virtual register of class RC. Return the virtual register 324 /// that is a copy of the live in PhysReg. 325 unsigned addLiveIn(unsigned PhysReg, const TargetRegisterClass *RC); 326 327 /// removeLiveIn - Remove the specified register from the live in set. 328 /// 329 void removeLiveIn(unsigned Reg); 330 331 /// isLiveIn - Return true if the specified register is in the live in set. 332 /// 333 bool isLiveIn(unsigned Reg) const; 334 335 // Iteration support for live in sets. These sets are kept in sorted 336 // order by their register number. 337 typedef std::vector<unsigned>::const_iterator livein_iterator; 338 livein_iterator livein_begin() const { return LiveIns.begin(); } 339 livein_iterator livein_end() const { return LiveIns.end(); } 340 bool livein_empty() const { return LiveIns.empty(); } 341 342 /// getAlignment - Return alignment of the basic block. 343 /// The alignment is specified as log2(bytes). 344 /// 345 unsigned getAlignment() const { return Alignment; } 346 347 /// setAlignment - Set alignment of the basic block. 348 /// The alignment is specified as log2(bytes). 349 /// 350 void setAlignment(unsigned Align) { Alignment = Align; } 351 352 /// isLandingPad - Returns true if the block is a landing pad. That is 353 /// this basic block is entered via an exception handler. 354 bool isLandingPad() const { return IsLandingPad; } 355 356 /// setIsLandingPad - Indicates the block is a landing pad. That is 357 /// this basic block is entered via an exception handler. 358 void setIsLandingPad(bool V = true) { IsLandingPad = V; } 359 360 /// getLandingPadSuccessor - If this block has a successor that is a landing 361 /// pad, return it. Otherwise return NULL. 362 const MachineBasicBlock *getLandingPadSuccessor() const; 363 364 // Code Layout methods. 365 366 /// moveBefore/moveAfter - move 'this' block before or after the specified 367 /// block. This only moves the block, it does not modify the CFG or adjust 368 /// potential fall-throughs at the end of the block. 369 void moveBefore(MachineBasicBlock *NewAfter); 370 void moveAfter(MachineBasicBlock *NewBefore); 371 372 /// updateTerminator - Update the terminator instructions in block to account 373 /// for changes to the layout. If the block previously used a fallthrough, 374 /// it may now need a branch, and if it previously used branching it may now 375 /// be able to use a fallthrough. 376 void updateTerminator(); 377 378 // Machine-CFG mutators 379 380 /// addSuccessor - Add succ as a successor of this MachineBasicBlock. 381 /// The Predecessors list of succ is automatically updated. WEIGHT 382 /// parameter is stored in Weights list and it may be used by 383 /// MachineBranchProbabilityInfo analysis to calculate branch probability. 384 /// 385 /// Note that duplicate Machine CFG edges are not allowed. 386 /// 387 void addSuccessor(MachineBasicBlock *succ, uint32_t weight = 0); 388 389 /// Set successor weight of a given iterator. 390 void setSuccWeight(succ_iterator I, uint32_t weight); 391 392 /// removeSuccessor - Remove successor from the successors list of this 393 /// MachineBasicBlock. The Predecessors list of succ is automatically updated. 394 /// 395 void removeSuccessor(MachineBasicBlock *succ); 396 397 /// removeSuccessor - Remove specified successor from the successors list of 398 /// this MachineBasicBlock. The Predecessors list of succ is automatically 399 /// updated. Return the iterator to the element after the one removed. 400 /// 401 succ_iterator removeSuccessor(succ_iterator I); 402 403 /// replaceSuccessor - Replace successor OLD with NEW and update weight info. 404 /// 405 void replaceSuccessor(MachineBasicBlock *Old, MachineBasicBlock *New); 406 407 408 /// transferSuccessors - Transfers all the successors from MBB to this 409 /// machine basic block (i.e., copies all the successors fromMBB and 410 /// remove all the successors from fromMBB). 411 void transferSuccessors(MachineBasicBlock *fromMBB); 412 413 /// transferSuccessorsAndUpdatePHIs - Transfers all the successors, as 414 /// in transferSuccessors, and update PHI operands in the successor blocks 415 /// which refer to fromMBB to refer to this. 416 void transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB); 417 418 /// isPredecessor - Return true if the specified MBB is a predecessor of this 419 /// block. 420 bool isPredecessor(const MachineBasicBlock *MBB) const; 421 422 /// isSuccessor - Return true if the specified MBB is a successor of this 423 /// block. 424 bool isSuccessor(const MachineBasicBlock *MBB) const; 425 426 /// isLayoutSuccessor - Return true if the specified MBB will be emitted 427 /// immediately after this block, such that if this block exits by 428 /// falling through, control will transfer to the specified MBB. Note 429 /// that MBB need not be a successor at all, for example if this block 430 /// ends with an unconditional branch to some other block. 431 bool isLayoutSuccessor(const MachineBasicBlock *MBB) const; 432 433 /// canFallThrough - Return true if the block can implicitly transfer 434 /// control to the block after it by falling off the end of it. This should 435 /// return false if it can reach the block after it, but it uses an explicit 436 /// branch to do so (e.g., a table jump). True is a conservative answer. 437 bool canFallThrough(); 438 439 /// Returns a pointer to the first instruction in this block that is not a 440 /// PHINode instruction. When adding instructions to the beginning of the 441 /// basic block, they should be added before the returned value, not before 442 /// the first instruction, which might be PHI. 443 /// Returns end() is there's no non-PHI instruction. 444 iterator getFirstNonPHI(); 445 446 /// SkipPHIsAndLabels - Return the first instruction in MBB after I that is 447 /// not a PHI or a label. This is the correct point to insert copies at the 448 /// beginning of a basic block. 449 iterator SkipPHIsAndLabels(iterator I); 450 451 /// getFirstTerminator - returns an iterator to the first terminator 452 /// instruction of this basic block. If a terminator does not exist, 453 /// it returns end() 454 iterator getFirstTerminator(); 455 const_iterator getFirstTerminator() const; 456 457 /// getFirstInstrTerminator - Same getFirstTerminator but it ignores bundles 458 /// and return an instr_iterator instead. 459 instr_iterator getFirstInstrTerminator(); 460 461 /// getLastNonDebugInstr - returns an iterator to the last non-debug 462 /// instruction in the basic block, or end() 463 iterator getLastNonDebugInstr(); 464 const_iterator getLastNonDebugInstr() const; 465 466 /// SplitCriticalEdge - Split the critical edge from this block to the 467 /// given successor block, and return the newly created block, or null 468 /// if splitting is not possible. 469 /// 470 /// This function updates LiveVariables, MachineDominatorTree, and 471 /// MachineLoopInfo, as applicable. 472 MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P); 473 474 void pop_front() { Insts.pop_front(); } 475 void pop_back() { Insts.pop_back(); } 476 void push_back(MachineInstr *MI) { Insts.push_back(MI); } 477 478 /// Insert MI into the instruction list before I, possibly inside a bundle. 479 /// 480 /// If the insertion point is inside a bundle, MI will be added to the bundle, 481 /// otherwise MI will not be added to any bundle. That means this function 482 /// alone can't be used to prepend or append instructions to bundles. See 483 /// MIBundleBuilder::insert() for a more reliable way of doing that. 484 instr_iterator insert(instr_iterator I, MachineInstr *M); 485 486 /// Insert a range of instructions into the instruction list before I. 487 template<typename IT> 488 void insert(iterator I, IT S, IT E) { 489 Insts.insert(I.getInstrIterator(), S, E); 490 } 491 492 /// Insert MI into the instruction list before I. 493 iterator insert(iterator I, MachineInstr *MI) { 494 assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() && 495 "Cannot insert instruction with bundle flags"); 496 return Insts.insert(I.getInstrIterator(), MI); 497 } 498 499 /// Insert MI into the instruction list after I. 500 iterator insertAfter(iterator I, MachineInstr *MI) { 501 assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() && 502 "Cannot insert instruction with bundle flags"); 503 return Insts.insertAfter(I.getInstrIterator(), MI); 504 } 505 506 /// Remove an instruction from the instruction list and delete it. 507 /// 508 /// If the instruction is part of a bundle, the other instructions in the 509 /// bundle will still be bundled after removing the single instruction. 510 instr_iterator erase(instr_iterator I); 511 512 /// Remove an instruction from the instruction list and delete it. 513 /// 514 /// If the instruction is part of a bundle, the other instructions in the 515 /// bundle will still be bundled after removing the single instruction. 516 instr_iterator erase_instr(MachineInstr *I) { 517 return erase(instr_iterator(I)); 518 } 519 520 /// Remove a range of instructions from the instruction list and delete them. 521 iterator erase(iterator I, iterator E) { 522 return Insts.erase(I.getInstrIterator(), E.getInstrIterator()); 523 } 524 525 /// Remove an instruction or bundle from the instruction list and delete it. 526 /// 527 /// If I points to a bundle of instructions, they are all erased. 528 iterator erase(iterator I) { 529 return erase(I, std::next(I)); 530 } 531 532 /// Remove an instruction from the instruction list and delete it. 533 /// 534 /// If I is the head of a bundle of instructions, the whole bundle will be 535 /// erased. 536 iterator erase(MachineInstr *I) { 537 return erase(iterator(I)); 538 } 539 540 /// Remove the unbundled instruction from the instruction list without 541 /// deleting it. 542 /// 543 /// This function can not be used to remove bundled instructions, use 544 /// remove_instr to remove individual instructions from a bundle. 545 MachineInstr *remove(MachineInstr *I) { 546 assert(!I->isBundled() && "Cannot remove bundled instructions"); 547 return Insts.remove(I); 548 } 549 550 /// Remove the possibly bundled instruction from the instruction list 551 /// without deleting it. 552 /// 553 /// If the instruction is part of a bundle, the other instructions in the 554 /// bundle will still be bundled after removing the single instruction. 555 MachineInstr *remove_instr(MachineInstr *I); 556 557 void clear() { 558 Insts.clear(); 559 } 560 561 /// Take an instruction from MBB 'Other' at the position From, and insert it 562 /// into this MBB right before 'Where'. 563 /// 564 /// If From points to a bundle of instructions, the whole bundle is moved. 565 void splice(iterator Where, MachineBasicBlock *Other, iterator From) { 566 // The range splice() doesn't allow noop moves, but this one does. 567 if (Where != From) 568 splice(Where, Other, From, std::next(From)); 569 } 570 571 /// Take a block of instructions from MBB 'Other' in the range [From, To), 572 /// and insert them into this MBB right before 'Where'. 573 /// 574 /// The instruction at 'Where' must not be included in the range of 575 /// instructions to move. 576 void splice(iterator Where, MachineBasicBlock *Other, 577 iterator From, iterator To) { 578 Insts.splice(Where.getInstrIterator(), Other->Insts, 579 From.getInstrIterator(), To.getInstrIterator()); 580 } 581 582 /// removeFromParent - This method unlinks 'this' from the containing 583 /// function, and returns it, but does not delete it. 584 MachineBasicBlock *removeFromParent(); 585 586 /// eraseFromParent - This method unlinks 'this' from the containing 587 /// function and deletes it. 588 void eraseFromParent(); 589 590 /// ReplaceUsesOfBlockWith - Given a machine basic block that branched to 591 /// 'Old', change the code and CFG so that it branches to 'New' instead. 592 void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New); 593 594 /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in 595 /// the CFG to be inserted. If we have proven that MBB can only branch to 596 /// DestA and DestB, remove any other MBB successors from the CFG. DestA and 597 /// DestB can be null. Besides DestA and DestB, retain other edges leading 598 /// to LandingPads (currently there can be only one; we don't check or require 599 /// that here). Note it is possible that DestA and/or DestB are LandingPads. 600 bool CorrectExtraCFGEdges(MachineBasicBlock *DestA, 601 MachineBasicBlock *DestB, 602 bool isCond); 603 604 /// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping 605 /// any DBG_VALUE instructions. Return UnknownLoc if there is none. 606 DebugLoc findDebugLoc(instr_iterator MBBI); 607 DebugLoc findDebugLoc(iterator MBBI) { 608 return findDebugLoc(MBBI.getInstrIterator()); 609 } 610 611 /// Possible outcome of a register liveness query to computeRegisterLiveness() 612 enum LivenessQueryResult { 613 LQR_Live, ///< Register is known to be live. 614 LQR_OverlappingLive, ///< Register itself is not live, but some overlapping 615 ///< register is. 616 LQR_Dead, ///< Register is known to be dead. 617 LQR_Unknown ///< Register liveness not decidable from local 618 ///< neighborhood. 619 }; 620 621 /// computeRegisterLiveness - Return whether (physical) register \c Reg 622 /// has been <def>ined and not <kill>ed as of just before \c MI. 623 /// 624 /// Search is localised to a neighborhood of 625 /// \c Neighborhood instructions before (searching for defs or kills) and 626 /// Neighborhood instructions after (searching just for defs) MI. 627 /// 628 /// \c Reg must be a physical register. 629 LivenessQueryResult computeRegisterLiveness(const TargetRegisterInfo *TRI, 630 unsigned Reg, MachineInstr *MI, 631 unsigned Neighborhood=10); 632 633 // Debugging methods. 634 void dump() const; 635 void print(raw_ostream &OS, SlotIndexes* = nullptr) const; 636 637 // Printing method used by LoopInfo. 638 void printAsOperand(raw_ostream &OS, bool PrintType = true) const; 639 640 /// getNumber - MachineBasicBlocks are uniquely numbered at the function 641 /// level, unless they're not in a MachineFunction yet, in which case this 642 /// will return -1. 643 /// 644 int getNumber() const { return Number; } 645 void setNumber(int N) { Number = N; } 646 647 /// getSymbol - Return the MCSymbol for this basic block. 648 /// 649 MCSymbol *getSymbol() const; 650 651 652 private: 653 /// getWeightIterator - Return weight iterator corresponding to the I 654 /// successor iterator. 655 weight_iterator getWeightIterator(succ_iterator I); 656 const_weight_iterator getWeightIterator(const_succ_iterator I) const; 657 658 friend class MachineBranchProbabilityInfo; 659 660 /// getSuccWeight - Return weight of the edge from this block to MBB. This 661 /// method should NOT be called directly, but by using getEdgeWeight method 662 /// from MachineBranchProbabilityInfo class. 663 uint32_t getSuccWeight(const_succ_iterator Succ) const; 664 665 666 // Methods used to maintain doubly linked list of blocks... 667 friend struct ilist_traits<MachineBasicBlock>; 668 669 // Machine-CFG mutators 670 671 /// addPredecessor - Remove pred as a predecessor of this MachineBasicBlock. 672 /// Don't do this unless you know what you're doing, because it doesn't 673 /// update pred's successors list. Use pred->addSuccessor instead. 674 /// 675 void addPredecessor(MachineBasicBlock *pred); 676 677 /// removePredecessor - Remove pred as a predecessor of this 678 /// MachineBasicBlock. Don't do this unless you know what you're 679 /// doing, because it doesn't update pred's successors list. Use 680 /// pred->removeSuccessor instead. 681 /// 682 void removePredecessor(MachineBasicBlock *pred); 683 }; 684 685 raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB); 686 687 // This is useful when building IndexedMaps keyed on basic block pointers. 688 struct MBB2NumberFunctor : 689 public std::unary_function<const MachineBasicBlock*, unsigned> { 690 unsigned operator()(const MachineBasicBlock *MBB) const { 691 return MBB->getNumber(); 692 } 693 }; 694 695 //===--------------------------------------------------------------------===// 696 // GraphTraits specializations for machine basic block graphs (machine-CFGs) 697 //===--------------------------------------------------------------------===// 698 699 // Provide specializations of GraphTraits to be able to treat a 700 // MachineFunction as a graph of MachineBasicBlocks... 701 // 702 703 template <> struct GraphTraits<MachineBasicBlock *> { 704 typedef MachineBasicBlock NodeType; 705 typedef MachineBasicBlock::succ_iterator ChildIteratorType; 706 707 static NodeType *getEntryNode(MachineBasicBlock *BB) { return BB; } 708 static inline ChildIteratorType child_begin(NodeType *N) { 709 return N->succ_begin(); 710 } 711 static inline ChildIteratorType child_end(NodeType *N) { 712 return N->succ_end(); 713 } 714 }; 715 716 template <> struct GraphTraits<const MachineBasicBlock *> { 717 typedef const MachineBasicBlock NodeType; 718 typedef MachineBasicBlock::const_succ_iterator ChildIteratorType; 719 720 static NodeType *getEntryNode(const MachineBasicBlock *BB) { return BB; } 721 static inline ChildIteratorType child_begin(NodeType *N) { 722 return N->succ_begin(); 723 } 724 static inline ChildIteratorType child_end(NodeType *N) { 725 return N->succ_end(); 726 } 727 }; 728 729 // Provide specializations of GraphTraits to be able to treat a 730 // MachineFunction as a graph of MachineBasicBlocks... and to walk it 731 // in inverse order. Inverse order for a function is considered 732 // to be when traversing the predecessor edges of a MBB 733 // instead of the successor edges. 734 // 735 template <> struct GraphTraits<Inverse<MachineBasicBlock*> > { 736 typedef MachineBasicBlock NodeType; 737 typedef MachineBasicBlock::pred_iterator ChildIteratorType; 738 static NodeType *getEntryNode(Inverse<MachineBasicBlock *> G) { 739 return G.Graph; 740 } 741 static inline ChildIteratorType child_begin(NodeType *N) { 742 return N->pred_begin(); 743 } 744 static inline ChildIteratorType child_end(NodeType *N) { 745 return N->pred_end(); 746 } 747 }; 748 749 template <> struct GraphTraits<Inverse<const MachineBasicBlock*> > { 750 typedef const MachineBasicBlock NodeType; 751 typedef MachineBasicBlock::const_pred_iterator ChildIteratorType; 752 static NodeType *getEntryNode(Inverse<const MachineBasicBlock*> G) { 753 return G.Graph; 754 } 755 static inline ChildIteratorType child_begin(NodeType *N) { 756 return N->pred_begin(); 757 } 758 static inline ChildIteratorType child_end(NodeType *N) { 759 return N->pred_end(); 760 } 761 }; 762 763 764 765 /// MachineInstrSpan provides an interface to get an iteration range 766 /// containing the instruction it was initialized with, along with all 767 /// those instructions inserted prior to or following that instruction 768 /// at some point after the MachineInstrSpan is constructed. 769 class MachineInstrSpan { 770 MachineBasicBlock &MBB; 771 MachineBasicBlock::iterator I, B, E; 772 public: 773 MachineInstrSpan(MachineBasicBlock::iterator I) 774 : MBB(*I->getParent()), 775 I(I), 776 B(I == MBB.begin() ? MBB.end() : std::prev(I)), 777 E(std::next(I)) {} 778 779 MachineBasicBlock::iterator begin() { 780 return B == MBB.end() ? MBB.begin() : std::next(B); 781 } 782 MachineBasicBlock::iterator end() { return E; } 783 bool empty() { return begin() == end(); } 784 785 MachineBasicBlock::iterator getInitial() { return I; } 786 }; 787 788 } // End llvm namespace 789 790 #endif 791