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/ADT/ilist.h" 19 #include "llvm/ADT/ilist_node.h" 20 #include "llvm/ADT/iterator_range.h" 21 #include "llvm/ADT/simple_ilist.h" 22 #include "llvm/CodeGen/MachineInstr.h" 23 #include "llvm/CodeGen/MachineInstrBundleIterator.h" 24 #include "llvm/IR/DebugLoc.h" 25 #include "llvm/MC/LaneBitmask.h" 26 #include "llvm/MC/MCRegisterInfo.h" 27 #include "llvm/Support/BranchProbability.h" 28 #include <cassert> 29 #include <cstdint> 30 #include <functional> 31 #include <iterator> 32 #include <string> 33 #include <vector> 34 35 namespace llvm { 36 37 class BasicBlock; 38 class MachineFunction; 39 class MCSymbol; 40 class ModuleSlotTracker; 41 class Pass; 42 class SlotIndexes; 43 class StringRef; 44 class raw_ostream; 45 class TargetRegisterClass; 46 class TargetRegisterInfo; 47 48 template <> struct ilist_traits<MachineInstr> { 49 private: 50 friend class MachineBasicBlock; // Set by the owning MachineBasicBlock. 51 52 MachineBasicBlock *Parent; 53 54 using instr_iterator = 55 simple_ilist<MachineInstr, ilist_sentinel_tracking<true>>::iterator; 56 57 public: 58 void addNodeToList(MachineInstr *N); 59 void removeNodeFromList(MachineInstr *N); 60 void transferNodesFromList(ilist_traits &OldList, instr_iterator First, 61 instr_iterator Last); 62 void deleteNode(MachineInstr *MI); 63 }; 64 65 class MachineBasicBlock 66 : public ilist_node_with_parent<MachineBasicBlock, MachineFunction> { 67 public: 68 /// Pair of physical register and lane mask. 69 /// This is not simply a std::pair typedef because the members should be named 70 /// clearly as they both have an integer type. 71 struct RegisterMaskPair { 72 public: 73 MCPhysReg PhysReg; 74 LaneBitmask LaneMask; 75 76 RegisterMaskPair(MCPhysReg PhysReg, LaneBitmask LaneMask) 77 : PhysReg(PhysReg), LaneMask(LaneMask) {} 78 }; 79 80 private: 81 using Instructions = ilist<MachineInstr, ilist_sentinel_tracking<true>>; 82 83 Instructions Insts; 84 const BasicBlock *BB; 85 int Number; 86 MachineFunction *xParent; 87 88 /// Keep track of the predecessor / successor basic blocks. 89 std::vector<MachineBasicBlock *> Predecessors; 90 std::vector<MachineBasicBlock *> Successors; 91 92 /// Keep track of the probabilities to the successors. This vector has the 93 /// same order as Successors, or it is empty if we don't use it (disable 94 /// optimization). 95 std::vector<BranchProbability> Probs; 96 using probability_iterator = std::vector<BranchProbability>::iterator; 97 using const_probability_iterator = 98 std::vector<BranchProbability>::const_iterator; 99 100 /// Keep track of the physical registers that are livein of the basicblock. 101 using LiveInVector = std::vector<RegisterMaskPair>; 102 LiveInVector LiveIns; 103 104 /// Alignment of the basic block. Zero if the basic block does not need to be 105 /// aligned. The alignment is specified as log2(bytes). 106 unsigned Alignment = 0; 107 108 /// Indicate that this basic block is entered via an exception handler. 109 bool IsEHPad = false; 110 111 /// Indicate that this basic block is potentially the target of an indirect 112 /// branch. 113 bool AddressTaken = false; 114 115 /// Indicate that this basic block is the entry block of an EH funclet. 116 bool IsEHFuncletEntry = false; 117 118 /// Indicate that this basic block is the entry block of a cleanup funclet. 119 bool IsCleanupFuncletEntry = false; 120 121 /// \brief since getSymbol is a relatively heavy-weight operation, the symbol 122 /// is only computed once and is cached. 123 mutable MCSymbol *CachedMCSymbol = nullptr; 124 125 // Intrusive list support 126 MachineBasicBlock() = default; 127 128 explicit MachineBasicBlock(MachineFunction &MF, const BasicBlock *BB); 129 130 ~MachineBasicBlock(); 131 132 // MachineBasicBlocks are allocated and owned by MachineFunction. 133 friend class MachineFunction; 134 135 public: 136 /// Return the LLVM basic block that this instance corresponded to originally. 137 /// Note that this may be NULL if this instance does not correspond directly 138 /// to an LLVM basic block. 139 const BasicBlock *getBasicBlock() const { return BB; } 140 141 /// Return the name of the corresponding LLVM basic block, or an empty string. 142 StringRef getName() const; 143 144 /// Return a formatted string to identify this block and its parent function. 145 std::string getFullName() const; 146 147 /// Test whether this block is potentially the target of an indirect branch. 148 bool hasAddressTaken() const { return AddressTaken; } 149 150 /// Set this block to reflect that it potentially is the target of an indirect 151 /// branch. 152 void setHasAddressTaken() { AddressTaken = true; } 153 154 /// Return the MachineFunction containing this basic block. 155 const MachineFunction *getParent() const { return xParent; } 156 MachineFunction *getParent() { return xParent; } 157 158 using instr_iterator = Instructions::iterator; 159 using const_instr_iterator = Instructions::const_iterator; 160 using reverse_instr_iterator = Instructions::reverse_iterator; 161 using const_reverse_instr_iterator = Instructions::const_reverse_iterator; 162 163 using iterator = MachineInstrBundleIterator<MachineInstr>; 164 using const_iterator = MachineInstrBundleIterator<const MachineInstr>; 165 using reverse_iterator = MachineInstrBundleIterator<MachineInstr, true>; 166 using const_reverse_iterator = 167 MachineInstrBundleIterator<const MachineInstr, true>; 168 169 unsigned size() const { return (unsigned)Insts.size(); } 170 bool empty() const { return Insts.empty(); } 171 172 MachineInstr &instr_front() { return Insts.front(); } 173 MachineInstr &instr_back() { return Insts.back(); } 174 const MachineInstr &instr_front() const { return Insts.front(); } 175 const MachineInstr &instr_back() const { return Insts.back(); } 176 177 MachineInstr &front() { return Insts.front(); } 178 MachineInstr &back() { return *--end(); } 179 const MachineInstr &front() const { return Insts.front(); } 180 const MachineInstr &back() const { return *--end(); } 181 182 instr_iterator instr_begin() { return Insts.begin(); } 183 const_instr_iterator instr_begin() const { return Insts.begin(); } 184 instr_iterator instr_end() { return Insts.end(); } 185 const_instr_iterator instr_end() const { return Insts.end(); } 186 reverse_instr_iterator instr_rbegin() { return Insts.rbegin(); } 187 const_reverse_instr_iterator instr_rbegin() const { return Insts.rbegin(); } 188 reverse_instr_iterator instr_rend () { return Insts.rend(); } 189 const_reverse_instr_iterator instr_rend () const { return Insts.rend(); } 190 191 using instr_range = iterator_range<instr_iterator>; 192 using const_instr_range = iterator_range<const_instr_iterator>; 193 instr_range instrs() { return instr_range(instr_begin(), instr_end()); } 194 const_instr_range instrs() const { 195 return const_instr_range(instr_begin(), instr_end()); 196 } 197 198 iterator begin() { return instr_begin(); } 199 const_iterator begin() const { return instr_begin(); } 200 iterator end () { return instr_end(); } 201 const_iterator end () const { return instr_end(); } 202 reverse_iterator rbegin() { 203 return reverse_iterator::getAtBundleBegin(instr_rbegin()); 204 } 205 const_reverse_iterator rbegin() const { 206 return const_reverse_iterator::getAtBundleBegin(instr_rbegin()); 207 } 208 reverse_iterator rend() { return reverse_iterator(instr_rend()); } 209 const_reverse_iterator rend() const { 210 return const_reverse_iterator(instr_rend()); 211 } 212 213 /// Support for MachineInstr::getNextNode(). 214 static Instructions MachineBasicBlock::*getSublistAccess(MachineInstr *) { 215 return &MachineBasicBlock::Insts; 216 } 217 218 inline iterator_range<iterator> terminators() { 219 return make_range(getFirstTerminator(), end()); 220 } 221 inline iterator_range<const_iterator> terminators() const { 222 return make_range(getFirstTerminator(), end()); 223 } 224 225 // Machine-CFG iterators 226 using pred_iterator = std::vector<MachineBasicBlock *>::iterator; 227 using const_pred_iterator = std::vector<MachineBasicBlock *>::const_iterator; 228 using succ_iterator = std::vector<MachineBasicBlock *>::iterator; 229 using const_succ_iterator = std::vector<MachineBasicBlock *>::const_iterator; 230 using pred_reverse_iterator = 231 std::vector<MachineBasicBlock *>::reverse_iterator; 232 using const_pred_reverse_iterator = 233 std::vector<MachineBasicBlock *>::const_reverse_iterator; 234 using succ_reverse_iterator = 235 std::vector<MachineBasicBlock *>::reverse_iterator; 236 using const_succ_reverse_iterator = 237 std::vector<MachineBasicBlock *>::const_reverse_iterator; 238 pred_iterator pred_begin() { return Predecessors.begin(); } 239 const_pred_iterator pred_begin() const { return Predecessors.begin(); } 240 pred_iterator pred_end() { return Predecessors.end(); } 241 const_pred_iterator pred_end() const { return Predecessors.end(); } 242 pred_reverse_iterator pred_rbegin() 243 { return Predecessors.rbegin();} 244 const_pred_reverse_iterator pred_rbegin() const 245 { return Predecessors.rbegin();} 246 pred_reverse_iterator pred_rend() 247 { return Predecessors.rend(); } 248 const_pred_reverse_iterator pred_rend() const 249 { return Predecessors.rend(); } 250 unsigned pred_size() const { 251 return (unsigned)Predecessors.size(); 252 } 253 bool pred_empty() const { return Predecessors.empty(); } 254 succ_iterator succ_begin() { return Successors.begin(); } 255 const_succ_iterator succ_begin() const { return Successors.begin(); } 256 succ_iterator succ_end() { return Successors.end(); } 257 const_succ_iterator succ_end() const { return Successors.end(); } 258 succ_reverse_iterator succ_rbegin() 259 { return Successors.rbegin(); } 260 const_succ_reverse_iterator succ_rbegin() const 261 { return Successors.rbegin(); } 262 succ_reverse_iterator succ_rend() 263 { return Successors.rend(); } 264 const_succ_reverse_iterator succ_rend() const 265 { return Successors.rend(); } 266 unsigned succ_size() const { 267 return (unsigned)Successors.size(); 268 } 269 bool succ_empty() const { return Successors.empty(); } 270 271 inline iterator_range<pred_iterator> predecessors() { 272 return make_range(pred_begin(), pred_end()); 273 } 274 inline iterator_range<const_pred_iterator> predecessors() const { 275 return make_range(pred_begin(), pred_end()); 276 } 277 inline iterator_range<succ_iterator> successors() { 278 return make_range(succ_begin(), succ_end()); 279 } 280 inline iterator_range<const_succ_iterator> successors() const { 281 return make_range(succ_begin(), succ_end()); 282 } 283 284 // LiveIn management methods. 285 286 /// Adds the specified register as a live in. Note that it is an error to add 287 /// the same register to the same set more than once unless the intention is 288 /// to call sortUniqueLiveIns after all registers are added. 289 void addLiveIn(MCPhysReg PhysReg, 290 LaneBitmask LaneMask = LaneBitmask::getAll()) { 291 LiveIns.push_back(RegisterMaskPair(PhysReg, LaneMask)); 292 } 293 void addLiveIn(const RegisterMaskPair &RegMaskPair) { 294 LiveIns.push_back(RegMaskPair); 295 } 296 297 /// Sorts and uniques the LiveIns vector. It can be significantly faster to do 298 /// this than repeatedly calling isLiveIn before calling addLiveIn for every 299 /// LiveIn insertion. 300 void sortUniqueLiveIns(); 301 302 /// Clear live in list. 303 void clearLiveIns(); 304 305 /// Add PhysReg as live in to this block, and ensure that there is a copy of 306 /// PhysReg to a virtual register of class RC. Return the virtual register 307 /// that is a copy of the live in PhysReg. 308 unsigned addLiveIn(MCPhysReg PhysReg, const TargetRegisterClass *RC); 309 310 /// Remove the specified register from the live in set. 311 void removeLiveIn(MCPhysReg Reg, 312 LaneBitmask LaneMask = LaneBitmask::getAll()); 313 314 /// Return true if the specified register is in the live in set. 315 bool isLiveIn(MCPhysReg Reg, 316 LaneBitmask LaneMask = LaneBitmask::getAll()) const; 317 318 // Iteration support for live in sets. These sets are kept in sorted 319 // order by their register number. 320 using livein_iterator = LiveInVector::const_iterator; 321 #ifndef NDEBUG 322 /// Unlike livein_begin, this method does not check that the liveness 323 /// information is accurate. Still for debug purposes it may be useful 324 /// to have iterators that won't assert if the liveness information 325 /// is not current. 326 livein_iterator livein_begin_dbg() const { return LiveIns.begin(); } 327 iterator_range<livein_iterator> liveins_dbg() const { 328 return make_range(livein_begin_dbg(), livein_end()); 329 } 330 #endif 331 livein_iterator livein_begin() const; 332 livein_iterator livein_end() const { return LiveIns.end(); } 333 bool livein_empty() const { return LiveIns.empty(); } 334 iterator_range<livein_iterator> liveins() const { 335 return make_range(livein_begin(), livein_end()); 336 } 337 338 /// Remove entry from the livein set and return iterator to the next. 339 livein_iterator removeLiveIn(livein_iterator I); 340 341 /// Get the clobber mask for the start of this basic block. Funclets use this 342 /// to prevent register allocation across funclet transitions. 343 const uint32_t *getBeginClobberMask(const TargetRegisterInfo *TRI) const; 344 345 /// Get the clobber mask for the end of the basic block. 346 /// \see getBeginClobberMask() 347 const uint32_t *getEndClobberMask(const TargetRegisterInfo *TRI) const; 348 349 /// Return alignment of the basic block. The alignment is specified as 350 /// log2(bytes). 351 unsigned getAlignment() const { return Alignment; } 352 353 /// Set alignment of the basic block. The alignment is specified as 354 /// log2(bytes). 355 void setAlignment(unsigned Align) { Alignment = Align; } 356 357 /// Returns true if the block is a landing pad. That is this basic block is 358 /// entered via an exception handler. 359 bool isEHPad() const { return IsEHPad; } 360 361 /// Indicates the block is a landing pad. That is this basic block is entered 362 /// via an exception handler. 363 void setIsEHPad(bool V = true) { IsEHPad = V; } 364 365 bool hasEHPadSuccessor() const; 366 367 /// Returns true if this is the entry block of an EH funclet. 368 bool isEHFuncletEntry() const { return IsEHFuncletEntry; } 369 370 /// Indicates if this is the entry block of an EH funclet. 371 void setIsEHFuncletEntry(bool V = true) { IsEHFuncletEntry = V; } 372 373 /// Returns true if this is the entry block of a cleanup funclet. 374 bool isCleanupFuncletEntry() const { return IsCleanupFuncletEntry; } 375 376 /// Indicates if this is the entry block of a cleanup funclet. 377 void setIsCleanupFuncletEntry(bool V = true) { IsCleanupFuncletEntry = V; } 378 379 // Code Layout methods. 380 381 /// Move 'this' block before or after the specified block. This only moves 382 /// the block, it does not modify the CFG or adjust potential fall-throughs at 383 /// the end of the block. 384 void moveBefore(MachineBasicBlock *NewAfter); 385 void moveAfter(MachineBasicBlock *NewBefore); 386 387 /// Update the terminator instructions in block to account for changes to the 388 /// layout. If the block previously used a fallthrough, it may now need a 389 /// branch, and if it previously used branching it may now be able to use a 390 /// fallthrough. 391 void updateTerminator(); 392 393 // Machine-CFG mutators 394 395 /// Add Succ as a successor of this MachineBasicBlock. The Predecessors list 396 /// of Succ is automatically updated. PROB parameter is stored in 397 /// Probabilities list. The default probability is set as unknown. Mixing 398 /// known and unknown probabilities in successor list is not allowed. When all 399 /// successors have unknown probabilities, 1 / N is returned as the 400 /// probability for each successor, where N is the number of successors. 401 /// 402 /// Note that duplicate Machine CFG edges are not allowed. 403 void addSuccessor(MachineBasicBlock *Succ, 404 BranchProbability Prob = BranchProbability::getUnknown()); 405 406 /// Add Succ as a successor of this MachineBasicBlock. The Predecessors list 407 /// of Succ is automatically updated. The probability is not provided because 408 /// BPI is not available (e.g. -O0 is used), in which case edge probabilities 409 /// won't be used. Using this interface can save some space. 410 void addSuccessorWithoutProb(MachineBasicBlock *Succ); 411 412 /// Set successor probability of a given iterator. 413 void setSuccProbability(succ_iterator I, BranchProbability Prob); 414 415 /// Normalize probabilities of all successors so that the sum of them becomes 416 /// one. This is usually done when the current update on this MBB is done, and 417 /// the sum of its successors' probabilities is not guaranteed to be one. The 418 /// user is responsible for the correct use of this function. 419 /// MBB::removeSuccessor() has an option to do this automatically. 420 void normalizeSuccProbs() { 421 BranchProbability::normalizeProbabilities(Probs.begin(), Probs.end()); 422 } 423 424 /// Validate successors' probabilities and check if the sum of them is 425 /// approximate one. This only works in DEBUG mode. 426 void validateSuccProbs() const; 427 428 /// Remove successor from the successors list of this MachineBasicBlock. The 429 /// Predecessors list of Succ is automatically updated. 430 /// If NormalizeSuccProbs is true, then normalize successors' probabilities 431 /// after the successor is removed. 432 void removeSuccessor(MachineBasicBlock *Succ, 433 bool NormalizeSuccProbs = false); 434 435 /// Remove specified successor from the successors list of this 436 /// MachineBasicBlock. The Predecessors list of Succ is automatically updated. 437 /// If NormalizeSuccProbs is true, then normalize successors' probabilities 438 /// after the successor is removed. 439 /// Return the iterator to the element after the one removed. 440 succ_iterator removeSuccessor(succ_iterator I, 441 bool NormalizeSuccProbs = false); 442 443 /// Replace successor OLD with NEW and update probability info. 444 void replaceSuccessor(MachineBasicBlock *Old, MachineBasicBlock *New); 445 446 /// Transfers all the successors from MBB to this machine basic block (i.e., 447 /// copies all the successors FromMBB and remove all the successors from 448 /// FromMBB). 449 void transferSuccessors(MachineBasicBlock *FromMBB); 450 451 /// Transfers all the successors, as in transferSuccessors, and update PHI 452 /// operands in the successor blocks which refer to FromMBB to refer to this. 453 void transferSuccessorsAndUpdatePHIs(MachineBasicBlock *FromMBB); 454 455 /// Return true if any of the successors have probabilities attached to them. 456 bool hasSuccessorProbabilities() const { return !Probs.empty(); } 457 458 /// Return true if the specified MBB is a predecessor of this block. 459 bool isPredecessor(const MachineBasicBlock *MBB) const; 460 461 /// Return true if the specified MBB is a successor of this block. 462 bool isSuccessor(const MachineBasicBlock *MBB) const; 463 464 /// Return true if the specified MBB will be emitted immediately after this 465 /// block, such that if this block exits by falling through, control will 466 /// transfer to the specified MBB. Note that MBB need not be a successor at 467 /// all, for example if this block ends with an unconditional branch to some 468 /// other block. 469 bool isLayoutSuccessor(const MachineBasicBlock *MBB) const; 470 471 /// Return the fallthrough block if the block can implicitly 472 /// transfer control to the block after it by falling off the end of 473 /// it. This should return null if it can reach the block after 474 /// it, but it uses an explicit branch to do so (e.g., a table 475 /// jump). Non-null return is a conservative answer. 476 MachineBasicBlock *getFallThrough(); 477 478 /// Return true if the block can implicitly transfer control to the 479 /// block after it by falling off the end of it. This should return 480 /// false if it can reach the block after it, but it uses an 481 /// explicit branch to do so (e.g., a table jump). True is a 482 /// conservative answer. 483 bool canFallThrough(); 484 485 /// Returns a pointer to the first instruction in this block that is not a 486 /// PHINode instruction. When adding instructions to the beginning of the 487 /// basic block, they should be added before the returned value, not before 488 /// the first instruction, which might be PHI. 489 /// Returns end() is there's no non-PHI instruction. 490 iterator getFirstNonPHI(); 491 492 /// Return the first instruction in MBB after I that is not a PHI or a label. 493 /// This is the correct point to insert lowered copies at the beginning of a 494 /// basic block that must be before any debugging information. 495 iterator SkipPHIsAndLabels(iterator I); 496 497 /// Return the first instruction in MBB after I that is not a PHI, label or 498 /// debug. This is the correct point to insert copies at the beginning of a 499 /// basic block. 500 iterator SkipPHIsLabelsAndDebug(iterator I); 501 502 /// Returns an iterator to the first terminator instruction of this basic 503 /// block. If a terminator does not exist, it returns end(). 504 iterator getFirstTerminator(); 505 const_iterator getFirstTerminator() const { 506 return const_cast<MachineBasicBlock *>(this)->getFirstTerminator(); 507 } 508 509 /// Same getFirstTerminator but it ignores bundles and return an 510 /// instr_iterator instead. 511 instr_iterator getFirstInstrTerminator(); 512 513 /// Returns an iterator to the first non-debug instruction in the basic block, 514 /// or end(). 515 iterator getFirstNonDebugInstr(); 516 const_iterator getFirstNonDebugInstr() const { 517 return const_cast<MachineBasicBlock *>(this)->getFirstNonDebugInstr(); 518 } 519 520 /// Returns an iterator to the last non-debug instruction in the basic block, 521 /// or end(). 522 iterator getLastNonDebugInstr(); 523 const_iterator getLastNonDebugInstr() const { 524 return const_cast<MachineBasicBlock *>(this)->getLastNonDebugInstr(); 525 } 526 527 /// Convenience function that returns true if the block ends in a return 528 /// instruction. 529 bool isReturnBlock() const { 530 return !empty() && back().isReturn(); 531 } 532 533 /// Split the critical edge from this block to the given successor block, and 534 /// return the newly created block, or null if splitting is not possible. 535 /// 536 /// This function updates LiveVariables, MachineDominatorTree, and 537 /// MachineLoopInfo, as applicable. 538 MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *Succ, Pass &P); 539 540 /// Check if the edge between this block and the given successor \p 541 /// Succ, can be split. If this returns true a subsequent call to 542 /// SplitCriticalEdge is guaranteed to return a valid basic block if 543 /// no changes occured in the meantime. 544 bool canSplitCriticalEdge(const MachineBasicBlock *Succ) const; 545 546 void pop_front() { Insts.pop_front(); } 547 void pop_back() { Insts.pop_back(); } 548 void push_back(MachineInstr *MI) { Insts.push_back(MI); } 549 550 /// Insert MI into the instruction list before I, possibly inside a bundle. 551 /// 552 /// If the insertion point is inside a bundle, MI will be added to the bundle, 553 /// otherwise MI will not be added to any bundle. That means this function 554 /// alone can't be used to prepend or append instructions to bundles. See 555 /// MIBundleBuilder::insert() for a more reliable way of doing that. 556 instr_iterator insert(instr_iterator I, MachineInstr *M); 557 558 /// Insert a range of instructions into the instruction list before I. 559 template<typename IT> 560 void insert(iterator I, IT S, IT E) { 561 assert((I == end() || I->getParent() == this) && 562 "iterator points outside of basic block"); 563 Insts.insert(I.getInstrIterator(), S, E); 564 } 565 566 /// Insert MI into the instruction list before I. 567 iterator insert(iterator I, MachineInstr *MI) { 568 assert((I == end() || I->getParent() == this) && 569 "iterator points outside of basic block"); 570 assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() && 571 "Cannot insert instruction with bundle flags"); 572 return Insts.insert(I.getInstrIterator(), MI); 573 } 574 575 /// Insert MI into the instruction list after I. 576 iterator insertAfter(iterator I, MachineInstr *MI) { 577 assert((I == end() || I->getParent() == this) && 578 "iterator points outside of basic block"); 579 assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() && 580 "Cannot insert instruction with bundle flags"); 581 return Insts.insertAfter(I.getInstrIterator(), MI); 582 } 583 584 /// Remove an instruction from the instruction list and delete it. 585 /// 586 /// If the instruction is part of a bundle, the other instructions in the 587 /// bundle will still be bundled after removing the single instruction. 588 instr_iterator erase(instr_iterator I); 589 590 /// Remove an instruction from the instruction list and delete it. 591 /// 592 /// If the instruction is part of a bundle, the other instructions in the 593 /// bundle will still be bundled after removing the single instruction. 594 instr_iterator erase_instr(MachineInstr *I) { 595 return erase(instr_iterator(I)); 596 } 597 598 /// Remove a range of instructions from the instruction list and delete them. 599 iterator erase(iterator I, iterator E) { 600 return Insts.erase(I.getInstrIterator(), E.getInstrIterator()); 601 } 602 603 /// Remove an instruction or bundle from the instruction list and delete it. 604 /// 605 /// If I points to a bundle of instructions, they are all erased. 606 iterator erase(iterator I) { 607 return erase(I, std::next(I)); 608 } 609 610 /// Remove an instruction from the instruction list and delete it. 611 /// 612 /// If I is the head of a bundle of instructions, the whole bundle will be 613 /// erased. 614 iterator erase(MachineInstr *I) { 615 return erase(iterator(I)); 616 } 617 618 /// Remove the unbundled instruction from the instruction list without 619 /// deleting it. 620 /// 621 /// This function can not be used to remove bundled instructions, use 622 /// remove_instr to remove individual instructions from a bundle. 623 MachineInstr *remove(MachineInstr *I) { 624 assert(!I->isBundled() && "Cannot remove bundled instructions"); 625 return Insts.remove(instr_iterator(I)); 626 } 627 628 /// Remove the possibly bundled instruction from the instruction list 629 /// without deleting it. 630 /// 631 /// If the instruction is part of a bundle, the other instructions in the 632 /// bundle will still be bundled after removing the single instruction. 633 MachineInstr *remove_instr(MachineInstr *I); 634 635 void clear() { 636 Insts.clear(); 637 } 638 639 /// Take an instruction from MBB 'Other' at the position From, and insert it 640 /// into this MBB right before 'Where'. 641 /// 642 /// If From points to a bundle of instructions, the whole bundle is moved. 643 void splice(iterator Where, MachineBasicBlock *Other, iterator From) { 644 // The range splice() doesn't allow noop moves, but this one does. 645 if (Where != From) 646 splice(Where, Other, From, std::next(From)); 647 } 648 649 /// Take a block of instructions from MBB 'Other' in the range [From, To), 650 /// and insert them into this MBB right before 'Where'. 651 /// 652 /// The instruction at 'Where' must not be included in the range of 653 /// instructions to move. 654 void splice(iterator Where, MachineBasicBlock *Other, 655 iterator From, iterator To) { 656 Insts.splice(Where.getInstrIterator(), Other->Insts, 657 From.getInstrIterator(), To.getInstrIterator()); 658 } 659 660 /// This method unlinks 'this' from the containing function, and returns it, 661 /// but does not delete it. 662 MachineBasicBlock *removeFromParent(); 663 664 /// This method unlinks 'this' from the containing function and deletes it. 665 void eraseFromParent(); 666 667 /// Given a machine basic block that branched to 'Old', change the code and 668 /// CFG so that it branches to 'New' instead. 669 void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New); 670 671 /// Various pieces of code can cause excess edges in the CFG to be inserted. 672 /// If we have proven that MBB can only branch to DestA and DestB, remove any 673 /// other MBB successors from the CFG. DestA and DestB can be null. Besides 674 /// DestA and DestB, retain other edges leading to LandingPads (currently 675 /// there can be only one; we don't check or require that here). Note it is 676 /// possible that DestA and/or DestB are LandingPads. 677 bool CorrectExtraCFGEdges(MachineBasicBlock *DestA, 678 MachineBasicBlock *DestB, 679 bool IsCond); 680 681 /// Find the next valid DebugLoc starting at MBBI, skipping any DBG_VALUE 682 /// instructions. Return UnknownLoc if there is none. 683 DebugLoc findDebugLoc(instr_iterator MBBI); 684 DebugLoc findDebugLoc(iterator MBBI) { 685 return findDebugLoc(MBBI.getInstrIterator()); 686 } 687 688 /// Find and return the merged DebugLoc of the branch instructions of the 689 /// block. Return UnknownLoc if there is none. 690 DebugLoc findBranchDebugLoc(); 691 692 /// Possible outcome of a register liveness query to computeRegisterLiveness() 693 enum LivenessQueryResult { 694 LQR_Live, ///< Register is known to be (at least partially) live. 695 LQR_Dead, ///< Register is known to be fully dead. 696 LQR_Unknown ///< Register liveness not decidable from local neighborhood. 697 }; 698 699 /// Return whether (physical) register \p Reg has been <def>ined and not 700 /// <kill>ed as of just before \p Before. 701 /// 702 /// Search is localised to a neighborhood of \p Neighborhood instructions 703 /// before (searching for defs or kills) and \p Neighborhood instructions 704 /// after (searching just for defs) \p Before. 705 /// 706 /// \p Reg must be a physical register. 707 LivenessQueryResult computeRegisterLiveness(const TargetRegisterInfo *TRI, 708 unsigned Reg, 709 const_iterator Before, 710 unsigned Neighborhood = 10) const; 711 712 // Debugging methods. 713 void dump() const; 714 void print(raw_ostream &OS, const SlotIndexes* = nullptr) const; 715 void print(raw_ostream &OS, ModuleSlotTracker &MST, 716 const SlotIndexes* = nullptr) const; 717 718 // Printing method used by LoopInfo. 719 void printAsOperand(raw_ostream &OS, bool PrintType = true) const; 720 721 /// MachineBasicBlocks are uniquely numbered at the function level, unless 722 /// they're not in a MachineFunction yet, in which case this will return -1. 723 int getNumber() const { return Number; } 724 void setNumber(int N) { Number = N; } 725 726 /// Return the MCSymbol for this basic block. 727 MCSymbol *getSymbol() const; 728 729 private: 730 /// Return probability iterator corresponding to the I successor iterator. 731 probability_iterator getProbabilityIterator(succ_iterator I); 732 const_probability_iterator 733 getProbabilityIterator(const_succ_iterator I) const; 734 735 friend class MachineBranchProbabilityInfo; 736 friend class MIPrinter; 737 738 /// Return probability of the edge from this block to MBB. This method should 739 /// NOT be called directly, but by using getEdgeProbability method from 740 /// MachineBranchProbabilityInfo class. 741 BranchProbability getSuccProbability(const_succ_iterator Succ) const; 742 743 // Methods used to maintain doubly linked list of blocks... 744 friend struct ilist_callback_traits<MachineBasicBlock>; 745 746 // Machine-CFG mutators 747 748 /// Remove Pred as a predecessor of this MachineBasicBlock. Don't do this 749 /// unless you know what you're doing, because it doesn't update Pred's 750 /// successors list. Use Pred->addSuccessor instead. 751 void addPredecessor(MachineBasicBlock *Pred); 752 753 /// Remove Pred as a predecessor of this MachineBasicBlock. Don't do this 754 /// unless you know what you're doing, because it doesn't update Pred's 755 /// successors list. Use Pred->removeSuccessor instead. 756 void removePredecessor(MachineBasicBlock *Pred); 757 }; 758 759 raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB); 760 761 // This is useful when building IndexedMaps keyed on basic block pointers. 762 struct MBB2NumberFunctor : 763 public std::unary_function<const MachineBasicBlock*, unsigned> { 764 unsigned operator()(const MachineBasicBlock *MBB) const { 765 return MBB->getNumber(); 766 } 767 }; 768 769 //===--------------------------------------------------------------------===// 770 // GraphTraits specializations for machine basic block graphs (machine-CFGs) 771 //===--------------------------------------------------------------------===// 772 773 // Provide specializations of GraphTraits to be able to treat a 774 // MachineFunction as a graph of MachineBasicBlocks. 775 // 776 777 template <> struct GraphTraits<MachineBasicBlock *> { 778 using NodeRef = MachineBasicBlock *; 779 using ChildIteratorType = MachineBasicBlock::succ_iterator; 780 781 static NodeRef getEntryNode(MachineBasicBlock *BB) { return BB; } 782 static ChildIteratorType child_begin(NodeRef N) { return N->succ_begin(); } 783 static ChildIteratorType child_end(NodeRef N) { return N->succ_end(); } 784 }; 785 786 template <> struct GraphTraits<const MachineBasicBlock *> { 787 using NodeRef = const MachineBasicBlock *; 788 using ChildIteratorType = MachineBasicBlock::const_succ_iterator; 789 790 static NodeRef getEntryNode(const MachineBasicBlock *BB) { return BB; } 791 static ChildIteratorType child_begin(NodeRef N) { return N->succ_begin(); } 792 static ChildIteratorType child_end(NodeRef N) { return N->succ_end(); } 793 }; 794 795 // Provide specializations of GraphTraits to be able to treat a 796 // MachineFunction as a graph of MachineBasicBlocks and to walk it 797 // in inverse order. Inverse order for a function is considered 798 // to be when traversing the predecessor edges of a MBB 799 // instead of the successor edges. 800 // 801 template <> struct GraphTraits<Inverse<MachineBasicBlock*>> { 802 using NodeRef = MachineBasicBlock *; 803 using ChildIteratorType = MachineBasicBlock::pred_iterator; 804 805 static NodeRef getEntryNode(Inverse<MachineBasicBlock *> G) { 806 return G.Graph; 807 } 808 809 static ChildIteratorType child_begin(NodeRef N) { return N->pred_begin(); } 810 static ChildIteratorType child_end(NodeRef N) { return N->pred_end(); } 811 }; 812 813 template <> struct GraphTraits<Inverse<const MachineBasicBlock*>> { 814 using NodeRef = const MachineBasicBlock *; 815 using ChildIteratorType = MachineBasicBlock::const_pred_iterator; 816 817 static NodeRef getEntryNode(Inverse<const MachineBasicBlock *> G) { 818 return G.Graph; 819 } 820 821 static ChildIteratorType child_begin(NodeRef N) { return N->pred_begin(); } 822 static ChildIteratorType child_end(NodeRef N) { return N->pred_end(); } 823 }; 824 825 /// MachineInstrSpan provides an interface to get an iteration range 826 /// containing the instruction it was initialized with, along with all 827 /// those instructions inserted prior to or following that instruction 828 /// at some point after the MachineInstrSpan is constructed. 829 class MachineInstrSpan { 830 MachineBasicBlock &MBB; 831 MachineBasicBlock::iterator I, B, E; 832 833 public: 834 MachineInstrSpan(MachineBasicBlock::iterator I) 835 : MBB(*I->getParent()), 836 I(I), 837 B(I == MBB.begin() ? MBB.end() : std::prev(I)), 838 E(std::next(I)) {} 839 840 MachineBasicBlock::iterator begin() { 841 return B == MBB.end() ? MBB.begin() : std::next(B); 842 } 843 MachineBasicBlock::iterator end() { return E; } 844 bool empty() { return begin() == end(); } 845 846 MachineBasicBlock::iterator getInitial() { return I; } 847 }; 848 849 /// Increment \p It until it points to a non-debug instruction or to \p End 850 /// and return the resulting iterator. This function should only be used 851 /// MachineBasicBlock::{iterator, const_iterator, instr_iterator, 852 /// const_instr_iterator} and the respective reverse iterators. 853 template<typename IterT> 854 inline IterT skipDebugInstructionsForward(IterT It, IterT End) { 855 while (It != End && It->isDebugValue()) 856 It++; 857 return It; 858 } 859 860 /// Decrement \p It until it points to a non-debug instruction or to \p Begin 861 /// and return the resulting iterator. This function should only be used 862 /// MachineBasicBlock::{iterator, const_iterator, instr_iterator, 863 /// const_instr_iterator} and the respective reverse iterators. 864 template<class IterT> 865 inline IterT skipDebugInstructionsBackward(IterT It, IterT Begin) { 866 while (It != Begin && It->isDebugValue()) 867 It--; 868 return It; 869 } 870 871 } // end namespace llvm 872 873 #endif // LLVM_CODEGEN_MACHINEBASICBLOCK_H 874