MachineBasicBlock.h revision 218893
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 /// getLandingPadSuccessor - If this block has a successor that is a landing 228 /// pad, return it. Otherwise return NULL. 229 const MachineBasicBlock *getLandingPadSuccessor() const; 230 231 // Code Layout methods. 232 233 /// moveBefore/moveAfter - move 'this' block before or after the specified 234 /// block. This only moves the block, it does not modify the CFG or adjust 235 /// potential fall-throughs at the end of the block. 236 void moveBefore(MachineBasicBlock *NewAfter); 237 void moveAfter(MachineBasicBlock *NewBefore); 238 239 /// updateTerminator - Update the terminator instructions in block to account 240 /// for changes to the layout. If the block previously used a fallthrough, 241 /// it may now need a branch, and if it previously used branching it may now 242 /// be able to use a fallthrough. 243 void updateTerminator(); 244 245 // Machine-CFG mutators 246 247 /// addSuccessor - Add succ as a successor of this MachineBasicBlock. 248 /// The Predecessors list of succ is automatically updated. 249 /// 250 void addSuccessor(MachineBasicBlock *succ); 251 252 /// removeSuccessor - Remove successor from the successors list of this 253 /// MachineBasicBlock. The Predecessors list of succ is automatically updated. 254 /// 255 void removeSuccessor(MachineBasicBlock *succ); 256 257 /// removeSuccessor - Remove specified successor from the successors list of 258 /// this MachineBasicBlock. The Predecessors list of succ is automatically 259 /// updated. Return the iterator to the element after the one removed. 260 /// 261 succ_iterator removeSuccessor(succ_iterator I); 262 263 /// transferSuccessors - Transfers all the successors from MBB to this 264 /// machine basic block (i.e., copies all the successors fromMBB and 265 /// remove all the successors from fromMBB). 266 void transferSuccessors(MachineBasicBlock *fromMBB); 267 268 /// transferSuccessorsAndUpdatePHIs - Transfers all the successors, as 269 /// in transferSuccessors, and update PHI operands in the successor blocks 270 /// which refer to fromMBB to refer to this. 271 void transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB); 272 273 /// isSuccessor - Return true if the specified MBB is a successor of this 274 /// block. 275 bool isSuccessor(const MachineBasicBlock *MBB) const; 276 277 /// isLayoutSuccessor - Return true if the specified MBB will be emitted 278 /// immediately after this block, such that if this block exits by 279 /// falling through, control will transfer to the specified MBB. Note 280 /// that MBB need not be a successor at all, for example if this block 281 /// ends with an unconditional branch to some other block. 282 bool isLayoutSuccessor(const MachineBasicBlock *MBB) const; 283 284 /// canFallThrough - Return true if the block can implicitly transfer 285 /// control to the block after it by falling off the end of it. This should 286 /// return false if it can reach the block after it, but it uses an explicit 287 /// branch to do so (e.g., a table jump). True is a conservative answer. 288 bool canFallThrough(); 289 290 /// Returns a pointer to the first instructon in this block that is not a 291 /// PHINode instruction. When adding instruction to the beginning of the 292 /// basic block, they should be added before the returned value, not before 293 /// the first instruction, which might be PHI. 294 /// Returns end() is there's no non-PHI instruction. 295 iterator getFirstNonPHI(); 296 297 /// SkipPHIsAndLabels - Return the first instruction in MBB after I that is 298 /// not a PHI or a label. This is the correct point to insert copies at the 299 /// beginning of a basic block. 300 iterator SkipPHIsAndLabels(iterator I); 301 302 /// getFirstTerminator - returns an iterator to the first terminator 303 /// instruction of this basic block. If a terminator does not exist, 304 /// it returns end() 305 iterator getFirstTerminator(); 306 307 /// getLastNonDebugInstr - returns an iterator to the last non-debug 308 /// instruction in the basic block, or end() 309 iterator getLastNonDebugInstr(); 310 311 /// SplitCriticalEdge - Split the critical edge from this block to the 312 /// given successor block, and return the newly created block, or null 313 /// if splitting is not possible. 314 /// 315 /// This function updates LiveVariables, MachineDominatorTree, and 316 /// MachineLoopInfo, as applicable. 317 MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P); 318 319 void pop_front() { Insts.pop_front(); } 320 void pop_back() { Insts.pop_back(); } 321 void push_back(MachineInstr *MI) { Insts.push_back(MI); } 322 template<typename IT> 323 void insert(iterator I, IT S, IT E) { Insts.insert(I, S, E); } 324 iterator insert(iterator I, MachineInstr *M) { return Insts.insert(I, M); } 325 iterator insertAfter(iterator I, MachineInstr *M) { 326 return Insts.insertAfter(I, M); 327 } 328 329 // erase - Remove the specified element or range from the instruction list. 330 // These functions delete any instructions removed. 331 // 332 iterator erase(iterator I) { return Insts.erase(I); } 333 iterator erase(iterator I, iterator E) { return Insts.erase(I, E); } 334 MachineInstr *remove(MachineInstr *I) { return Insts.remove(I); } 335 void clear() { Insts.clear(); } 336 337 /// splice - Take an instruction from MBB 'Other' at the position From, 338 /// and insert it into this MBB right before 'where'. 339 void splice(iterator where, MachineBasicBlock *Other, iterator From) { 340 Insts.splice(where, Other->Insts, From); 341 } 342 343 /// splice - Take a block of instructions from MBB 'Other' in the range [From, 344 /// To), and insert them into this MBB right before 'where'. 345 void splice(iterator where, MachineBasicBlock *Other, iterator From, 346 iterator To) { 347 Insts.splice(where, Other->Insts, From, To); 348 } 349 350 /// removeFromParent - This method unlinks 'this' from the containing 351 /// function, and returns it, but does not delete it. 352 MachineBasicBlock *removeFromParent(); 353 354 /// eraseFromParent - This method unlinks 'this' from the containing 355 /// function and deletes it. 356 void eraseFromParent(); 357 358 /// ReplaceUsesOfBlockWith - Given a machine basic block that branched to 359 /// 'Old', change the code and CFG so that it branches to 'New' instead. 360 void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New); 361 362 /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in 363 /// the CFG to be inserted. If we have proven that MBB can only branch to 364 /// DestA and DestB, remove any other MBB successors from the CFG. DestA and 365 /// DestB can be null. Besides DestA and DestB, retain other edges leading 366 /// to LandingPads (currently there can be only one; we don't check or require 367 /// that here). Note it is possible that DestA and/or DestB are LandingPads. 368 bool CorrectExtraCFGEdges(MachineBasicBlock *DestA, 369 MachineBasicBlock *DestB, 370 bool isCond); 371 372 /// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping 373 /// any DBG_VALUE instructions. Return UnknownLoc if there is none. 374 DebugLoc findDebugLoc(MachineBasicBlock::iterator &MBBI); 375 376 // Debugging methods. 377 void dump() const; 378 void print(raw_ostream &OS, SlotIndexes* = 0) const; 379 380 /// getNumber - MachineBasicBlocks are uniquely numbered at the function 381 /// level, unless they're not in a MachineFunction yet, in which case this 382 /// will return -1. 383 /// 384 int getNumber() const { return Number; } 385 void setNumber(int N) { Number = N; } 386 387 /// getSymbol - Return the MCSymbol for this basic block. 388 /// 389 MCSymbol *getSymbol() const; 390 391private: // Methods used to maintain doubly linked list of blocks... 392 friend struct ilist_traits<MachineBasicBlock>; 393 394 // Machine-CFG mutators 395 396 /// addPredecessor - Remove pred as a predecessor of this MachineBasicBlock. 397 /// Don't do this unless you know what you're doing, because it doesn't 398 /// update pred's successors list. Use pred->addSuccessor instead. 399 /// 400 void addPredecessor(MachineBasicBlock *pred); 401 402 /// removePredecessor - Remove pred as a predecessor of this 403 /// MachineBasicBlock. Don't do this unless you know what you're 404 /// doing, because it doesn't update pred's successors list. Use 405 /// pred->removeSuccessor instead. 406 /// 407 void removePredecessor(MachineBasicBlock *pred); 408}; 409 410raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB); 411 412void WriteAsOperand(raw_ostream &, const MachineBasicBlock*, bool t); 413 414//===--------------------------------------------------------------------===// 415// GraphTraits specializations for machine basic block graphs (machine-CFGs) 416//===--------------------------------------------------------------------===// 417 418// Provide specializations of GraphTraits to be able to treat a 419// MachineFunction as a graph of MachineBasicBlocks... 420// 421 422template <> struct GraphTraits<MachineBasicBlock *> { 423 typedef MachineBasicBlock NodeType; 424 typedef MachineBasicBlock::succ_iterator ChildIteratorType; 425 426 static NodeType *getEntryNode(MachineBasicBlock *BB) { return BB; } 427 static inline ChildIteratorType child_begin(NodeType *N) { 428 return N->succ_begin(); 429 } 430 static inline ChildIteratorType child_end(NodeType *N) { 431 return N->succ_end(); 432 } 433}; 434 435template <> struct GraphTraits<const MachineBasicBlock *> { 436 typedef const MachineBasicBlock NodeType; 437 typedef MachineBasicBlock::const_succ_iterator ChildIteratorType; 438 439 static NodeType *getEntryNode(const MachineBasicBlock *BB) { return BB; } 440 static inline ChildIteratorType child_begin(NodeType *N) { 441 return N->succ_begin(); 442 } 443 static inline ChildIteratorType child_end(NodeType *N) { 444 return N->succ_end(); 445 } 446}; 447 448// Provide specializations of GraphTraits to be able to treat a 449// MachineFunction as a graph of MachineBasicBlocks... and to walk it 450// in inverse order. Inverse order for a function is considered 451// to be when traversing the predecessor edges of a MBB 452// instead of the successor edges. 453// 454template <> struct GraphTraits<Inverse<MachineBasicBlock*> > { 455 typedef MachineBasicBlock NodeType; 456 typedef MachineBasicBlock::pred_iterator ChildIteratorType; 457 static NodeType *getEntryNode(Inverse<MachineBasicBlock *> G) { 458 return G.Graph; 459 } 460 static inline ChildIteratorType child_begin(NodeType *N) { 461 return N->pred_begin(); 462 } 463 static inline ChildIteratorType child_end(NodeType *N) { 464 return N->pred_end(); 465 } 466}; 467 468template <> struct GraphTraits<Inverse<const MachineBasicBlock*> > { 469 typedef const MachineBasicBlock NodeType; 470 typedef MachineBasicBlock::const_pred_iterator ChildIteratorType; 471 static NodeType *getEntryNode(Inverse<const MachineBasicBlock*> G) { 472 return G.Graph; 473 } 474 static inline ChildIteratorType child_begin(NodeType *N) { 475 return N->pred_begin(); 476 } 477 static inline ChildIteratorType child_end(NodeType *N) { 478 return N->pred_end(); 479 } 480}; 481 482} // End llvm namespace 483 484#endif 485