MachineBasicBlock.h revision f4a1e1a69f0727762a73ef0d551e3bbd16b7c04e
1//===-- llvm/CodeGen/MachineBasicBlock.h ------------------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// Collect the sequence of machine instructions for a basic block. 11// 12//===----------------------------------------------------------------------===// 13 14#ifndef LLVM_CODEGEN_MACHINEBASICBLOCK_H 15#define LLVM_CODEGEN_MACHINEBASICBLOCK_H 16 17#include "llvm/CodeGen/MachineInstr.h" 18#include "llvm/ADT/GraphTraits.h" 19 20namespace llvm { 21 22class Pass; 23class BasicBlock; 24class MachineFunction; 25class MCSymbol; 26class SlotIndexes; 27class StringRef; 28class raw_ostream; 29 30template <> 31struct ilist_traits<MachineInstr> : public ilist_default_traits<MachineInstr> { 32private: 33 mutable ilist_half_node<MachineInstr> Sentinel; 34 35 // this is only set by the MachineBasicBlock owning the LiveList 36 friend class MachineBasicBlock; 37 MachineBasicBlock* Parent; 38 39public: 40 MachineInstr *createSentinel() const { 41 return static_cast<MachineInstr*>(&Sentinel); 42 } 43 void destroySentinel(MachineInstr *) const {} 44 45 MachineInstr *provideInitialHead() const { return createSentinel(); } 46 MachineInstr *ensureHead(MachineInstr*) const { return createSentinel(); } 47 static void noteHead(MachineInstr*, MachineInstr*) {} 48 49 void addNodeToList(MachineInstr* N); 50 void removeNodeFromList(MachineInstr* N); 51 void transferNodesFromList(ilist_traits &SrcTraits, 52 ilist_iterator<MachineInstr> first, 53 ilist_iterator<MachineInstr> last); 54 void deleteNode(MachineInstr *N); 55private: 56 void createNode(const MachineInstr &); 57}; 58 59class MachineBasicBlock : public ilist_node<MachineBasicBlock> { 60 typedef ilist<MachineInstr> Instructions; 61 Instructions Insts; 62 const BasicBlock *BB; 63 int Number; 64 MachineFunction *xParent; 65 66 /// Predecessors/Successors - Keep track of the predecessor / successor 67 /// basicblocks. 68 std::vector<MachineBasicBlock *> Predecessors; 69 std::vector<MachineBasicBlock *> Successors; 70 71 /// LiveIns - Keep track of the physical registers that are livein of 72 /// the basicblock. 73 std::vector<unsigned> LiveIns; 74 75 /// Alignment - Alignment of the basic block. Zero if the basic block does 76 /// not need to be aligned. 77 unsigned Alignment; 78 79 /// IsLandingPad - Indicate that this basic block is entered via an 80 /// exception handler. 81 bool IsLandingPad; 82 83 /// AddressTaken - Indicate that this basic block is potentially the 84 /// target of an indirect branch. 85 bool AddressTaken; 86 87 // Intrusive list support 88 MachineBasicBlock() {} 89 90 explicit MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb); 91 92 ~MachineBasicBlock(); 93 94 // MachineBasicBlocks are allocated and owned by MachineFunction. 95 friend class MachineFunction; 96 97public: 98 /// getBasicBlock - Return the LLVM basic block that this instance 99 /// corresponded to originally. Note that this may be NULL if this instance 100 /// does not correspond directly to an LLVM basic block. 101 /// 102 const BasicBlock *getBasicBlock() const { return BB; } 103 104 /// getName - Return the name of the corresponding LLVM basic block, or 105 /// "(null)". 106 StringRef getName() const; 107 108 /// hasAddressTaken - Test whether this block is potentially the target 109 /// of an indirect branch. 110 bool hasAddressTaken() const { return AddressTaken; } 111 112 /// setHasAddressTaken - Set this block to reflect that it potentially 113 /// is the target of an indirect branch. 114 void setHasAddressTaken() { AddressTaken = true; } 115 116 /// getParent - Return the MachineFunction containing this basic block. 117 /// 118 const MachineFunction *getParent() const { return xParent; } 119 MachineFunction *getParent() { return xParent; } 120 121 typedef Instructions::iterator iterator; 122 typedef Instructions::const_iterator const_iterator; 123 typedef std::reverse_iterator<const_iterator> const_reverse_iterator; 124 typedef std::reverse_iterator<iterator> reverse_iterator; 125 126 unsigned size() const { return (unsigned)Insts.size(); } 127 bool empty() const { return Insts.empty(); } 128 129 MachineInstr& front() { return Insts.front(); } 130 MachineInstr& back() { return Insts.back(); } 131 const MachineInstr& front() const { return Insts.front(); } 132 const MachineInstr& back() const { return Insts.back(); } 133 134 iterator begin() { return Insts.begin(); } 135 const_iterator begin() const { return Insts.begin(); } 136 iterator end() { return Insts.end(); } 137 const_iterator end() const { return Insts.end(); } 138 reverse_iterator rbegin() { return Insts.rbegin(); } 139 const_reverse_iterator rbegin() const { return Insts.rbegin(); } 140 reverse_iterator rend () { return Insts.rend(); } 141 const_reverse_iterator rend () const { return Insts.rend(); } 142 143 // Machine-CFG iterators 144 typedef std::vector<MachineBasicBlock *>::iterator pred_iterator; 145 typedef std::vector<MachineBasicBlock *>::const_iterator const_pred_iterator; 146 typedef std::vector<MachineBasicBlock *>::iterator succ_iterator; 147 typedef std::vector<MachineBasicBlock *>::const_iterator const_succ_iterator; 148 typedef std::vector<MachineBasicBlock *>::reverse_iterator 149 pred_reverse_iterator; 150 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator 151 const_pred_reverse_iterator; 152 typedef std::vector<MachineBasicBlock *>::reverse_iterator 153 succ_reverse_iterator; 154 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator 155 const_succ_reverse_iterator; 156 157 pred_iterator pred_begin() { return Predecessors.begin(); } 158 const_pred_iterator pred_begin() const { return Predecessors.begin(); } 159 pred_iterator pred_end() { return Predecessors.end(); } 160 const_pred_iterator pred_end() const { return Predecessors.end(); } 161 pred_reverse_iterator pred_rbegin() 162 { return Predecessors.rbegin();} 163 const_pred_reverse_iterator pred_rbegin() const 164 { return Predecessors.rbegin();} 165 pred_reverse_iterator pred_rend() 166 { return Predecessors.rend(); } 167 const_pred_reverse_iterator pred_rend() const 168 { return Predecessors.rend(); } 169 unsigned pred_size() const { 170 return (unsigned)Predecessors.size(); 171 } 172 bool pred_empty() const { return Predecessors.empty(); } 173 succ_iterator succ_begin() { return Successors.begin(); } 174 const_succ_iterator succ_begin() const { return Successors.begin(); } 175 succ_iterator succ_end() { return Successors.end(); } 176 const_succ_iterator succ_end() const { return Successors.end(); } 177 succ_reverse_iterator succ_rbegin() 178 { return Successors.rbegin(); } 179 const_succ_reverse_iterator succ_rbegin() const 180 { return Successors.rbegin(); } 181 succ_reverse_iterator succ_rend() 182 { return Successors.rend(); } 183 const_succ_reverse_iterator succ_rend() const 184 { return Successors.rend(); } 185 unsigned succ_size() const { 186 return (unsigned)Successors.size(); 187 } 188 bool succ_empty() const { return Successors.empty(); } 189 190 // LiveIn management methods. 191 192 /// addLiveIn - Add the specified register as a live in. Note that it 193 /// is an error to add the same register to the same set more than once. 194 void addLiveIn(unsigned Reg) { LiveIns.push_back(Reg); } 195 196 /// removeLiveIn - Remove the specified register from the live in set. 197 /// 198 void removeLiveIn(unsigned Reg); 199 200 /// isLiveIn - Return true if the specified register is in the live in set. 201 /// 202 bool isLiveIn(unsigned Reg) const; 203 204 // Iteration support for live in sets. These sets are kept in sorted 205 // order by their register number. 206 typedef std::vector<unsigned>::const_iterator livein_iterator; 207 livein_iterator livein_begin() const { return LiveIns.begin(); } 208 livein_iterator livein_end() const { return LiveIns.end(); } 209 bool livein_empty() const { return LiveIns.empty(); } 210 211 /// getAlignment - Return alignment of the basic block. 212 /// 213 unsigned getAlignment() const { return Alignment; } 214 215 /// setAlignment - Set alignment of the basic block. 216 /// 217 void setAlignment(unsigned Align) { Alignment = Align; } 218 219 /// isLandingPad - Returns true if the block is a landing pad. That is 220 /// this basic block is entered via an exception handler. 221 bool isLandingPad() const { return IsLandingPad; } 222 223 /// setIsLandingPad - Indicates the block is a landing pad. That is 224 /// this basic block is entered via an exception handler. 225 void setIsLandingPad() { IsLandingPad = true; } 226 227 // Code Layout methods. 228 229 /// moveBefore/moveAfter - move 'this' block before or after the specified 230 /// block. This only moves the block, it does not modify the CFG or adjust 231 /// potential fall-throughs at the end of the block. 232 void moveBefore(MachineBasicBlock *NewAfter); 233 void moveAfter(MachineBasicBlock *NewBefore); 234 235 /// updateTerminator - Update the terminator instructions in block to account 236 /// for changes to the layout. If the block previously used a fallthrough, 237 /// it may now need a branch, and if it previously used branching it may now 238 /// be able to use a fallthrough. 239 void updateTerminator(); 240 241 // Machine-CFG mutators 242 243 /// addSuccessor - Add succ as a successor of this MachineBasicBlock. 244 /// The Predecessors list of succ is automatically updated. 245 /// 246 void addSuccessor(MachineBasicBlock *succ); 247 248 /// removeSuccessor - Remove successor from the successors list of this 249 /// MachineBasicBlock. The Predecessors list of succ is automatically updated. 250 /// 251 void removeSuccessor(MachineBasicBlock *succ); 252 253 /// removeSuccessor - Remove specified successor from the successors list of 254 /// this MachineBasicBlock. The Predecessors list of succ is automatically 255 /// updated. Return the iterator to the element after the one removed. 256 /// 257 succ_iterator removeSuccessor(succ_iterator I); 258 259 /// transferSuccessors - Transfers all the successors from MBB to this 260 /// machine basic block (i.e., copies all the successors fromMBB and 261 /// remove all the successors from fromMBB). 262 void transferSuccessors(MachineBasicBlock *fromMBB); 263 264 /// transferSuccessorsAndUpdatePHIs - Transfers all the successors, as 265 /// in transferSuccessors, and update PHI operands in the successor blocks 266 /// which refer to fromMBB to refer to this. 267 void transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB); 268 269 /// isSuccessor - Return true if the specified MBB is a successor of this 270 /// block. 271 bool isSuccessor(const MachineBasicBlock *MBB) const; 272 273 /// isLayoutSuccessor - Return true if the specified MBB will be emitted 274 /// immediately after this block, such that if this block exits by 275 /// falling through, control will transfer to the specified MBB. Note 276 /// that MBB need not be a successor at all, for example if this block 277 /// ends with an unconditional branch to some other block. 278 bool isLayoutSuccessor(const MachineBasicBlock *MBB) const; 279 280 /// canFallThrough - Return true if the block can implicitly transfer 281 /// control to the block after it by falling off the end of it. This should 282 /// return false if it can reach the block after it, but it uses an explicit 283 /// branch to do so (e.g., a table jump). True is a conservative answer. 284 bool canFallThrough(); 285 286 /// Returns a pointer to the first instructon in this block that is not a 287 /// PHINode instruction. When adding instruction to the beginning of the 288 /// basic block, they should be added before the returned value, not before 289 /// the first instruction, which might be PHI. 290 /// Returns end() is there's no non-PHI instruction. 291 iterator getFirstNonPHI(); 292 293 /// getFirstTerminator - returns an iterator to the first terminator 294 /// instruction of this basic block. If a terminator does not exist, 295 /// it returns end() 296 iterator getFirstTerminator(); 297 298 /// SplitCriticalEdge - Split the critical edge from this block to the 299 /// given successor block, and return the newly created block, or null 300 /// if splitting is not possible. 301 /// 302 /// This function updates LiveVariables, MachineDominatorTree, and 303 /// MachineLoopInfo, as applicable. 304 MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P); 305 306 void pop_front() { Insts.pop_front(); } 307 void pop_back() { Insts.pop_back(); } 308 void push_back(MachineInstr *MI) { Insts.push_back(MI); } 309 template<typename IT> 310 void insert(iterator I, IT S, IT E) { Insts.insert(I, S, E); } 311 iterator insert(iterator I, MachineInstr *M) { return Insts.insert(I, M); } 312 iterator insertAfter(iterator I, MachineInstr *M) { 313 return Insts.insertAfter(I, M); 314 } 315 316 // erase - Remove the specified element or range from the instruction list. 317 // These functions delete any instructions removed. 318 // 319 iterator erase(iterator I) { return Insts.erase(I); } 320 iterator erase(iterator I, iterator E) { return Insts.erase(I, E); } 321 MachineInstr *remove(MachineInstr *I) { return Insts.remove(I); } 322 void clear() { Insts.clear(); } 323 324 /// splice - Take an instruction from MBB 'Other' at the position From, 325 /// and insert it into this MBB right before 'where'. 326 void splice(iterator where, MachineBasicBlock *Other, iterator From) { 327 Insts.splice(where, Other->Insts, From); 328 } 329 330 /// splice - Take a block of instructions from MBB 'Other' in the range [From, 331 /// To), and insert them into this MBB right before 'where'. 332 void splice(iterator where, MachineBasicBlock *Other, iterator From, 333 iterator To) { 334 Insts.splice(where, Other->Insts, From, To); 335 } 336 337 /// removeFromParent - This method unlinks 'this' from the containing 338 /// function, and returns it, but does not delete it. 339 MachineBasicBlock *removeFromParent(); 340 341 /// eraseFromParent - This method unlinks 'this' from the containing 342 /// function and deletes it. 343 void eraseFromParent(); 344 345 /// ReplaceUsesOfBlockWith - Given a machine basic block that branched to 346 /// 'Old', change the code and CFG so that it branches to 'New' instead. 347 void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New); 348 349 /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in 350 /// the CFG to be inserted. If we have proven that MBB can only branch to 351 /// DestA and DestB, remove any other MBB successors from the CFG. DestA and 352 /// DestB can be null. Besides DestA and DestB, retain other edges leading 353 /// to LandingPads (currently there can be only one; we don't check or require 354 /// that here). Note it is possible that DestA and/or DestB are LandingPads. 355 bool CorrectExtraCFGEdges(MachineBasicBlock *DestA, 356 MachineBasicBlock *DestB, 357 bool isCond); 358 359 /// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping 360 /// any DBG_VALUE instructions. Return UnknownLoc if there is none. 361 DebugLoc findDebugLoc(MachineBasicBlock::iterator &MBBI); 362 363 // Debugging methods. 364 void dump() const; 365 void print(raw_ostream &OS, SlotIndexes* = 0) const; 366 367 /// getNumber - MachineBasicBlocks are uniquely numbered at the function 368 /// level, unless they're not in a MachineFunction yet, in which case this 369 /// will return -1. 370 /// 371 int getNumber() const { return Number; } 372 void setNumber(int N) { Number = N; } 373 374 /// getSymbol - Return the MCSymbol for this basic block. 375 /// 376 MCSymbol *getSymbol() const; 377 378private: // Methods used to maintain doubly linked list of blocks... 379 friend struct ilist_traits<MachineBasicBlock>; 380 381 // Machine-CFG mutators 382 383 /// addPredecessor - Remove pred as a predecessor of this MachineBasicBlock. 384 /// Don't do this unless you know what you're doing, because it doesn't 385 /// update pred's successors list. Use pred->addSuccessor instead. 386 /// 387 void addPredecessor(MachineBasicBlock *pred); 388 389 /// removePredecessor - Remove pred as a predecessor of this 390 /// MachineBasicBlock. Don't do this unless you know what you're 391 /// doing, because it doesn't update pred's successors list. Use 392 /// pred->removeSuccessor instead. 393 /// 394 void removePredecessor(MachineBasicBlock *pred); 395}; 396 397raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB); 398 399void WriteAsOperand(raw_ostream &, const MachineBasicBlock*, bool t); 400 401//===--------------------------------------------------------------------===// 402// GraphTraits specializations for machine basic block graphs (machine-CFGs) 403//===--------------------------------------------------------------------===// 404 405// Provide specializations of GraphTraits to be able to treat a 406// MachineFunction as a graph of MachineBasicBlocks... 407// 408 409template <> struct GraphTraits<MachineBasicBlock *> { 410 typedef MachineBasicBlock NodeType; 411 typedef MachineBasicBlock::succ_iterator ChildIteratorType; 412 413 static NodeType *getEntryNode(MachineBasicBlock *BB) { return BB; } 414 static inline ChildIteratorType child_begin(NodeType *N) { 415 return N->succ_begin(); 416 } 417 static inline ChildIteratorType child_end(NodeType *N) { 418 return N->succ_end(); 419 } 420}; 421 422template <> struct GraphTraits<const MachineBasicBlock *> { 423 typedef const MachineBasicBlock NodeType; 424 typedef MachineBasicBlock::const_succ_iterator ChildIteratorType; 425 426 static NodeType *getEntryNode(const 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}; 434 435// Provide specializations of GraphTraits to be able to treat a 436// MachineFunction as a graph of MachineBasicBlocks... and to walk it 437// in inverse order. Inverse order for a function is considered 438// to be when traversing the predecessor edges of a MBB 439// instead of the successor edges. 440// 441template <> struct GraphTraits<Inverse<MachineBasicBlock*> > { 442 typedef MachineBasicBlock NodeType; 443 typedef MachineBasicBlock::pred_iterator ChildIteratorType; 444 static NodeType *getEntryNode(Inverse<MachineBasicBlock *> G) { 445 return G.Graph; 446 } 447 static inline ChildIteratorType child_begin(NodeType *N) { 448 return N->pred_begin(); 449 } 450 static inline ChildIteratorType child_end(NodeType *N) { 451 return N->pred_end(); 452 } 453}; 454 455template <> struct GraphTraits<Inverse<const MachineBasicBlock*> > { 456 typedef const MachineBasicBlock NodeType; 457 typedef MachineBasicBlock::const_pred_iterator ChildIteratorType; 458 static NodeType *getEntryNode(Inverse<const MachineBasicBlock*> G) { 459 return G.Graph; 460 } 461 static inline ChildIteratorType child_begin(NodeType *N) { 462 return N->pred_begin(); 463 } 464 static inline ChildIteratorType child_end(NodeType *N) { 465 return N->pred_end(); 466 } 467}; 468 469} // End llvm namespace 470 471#endif 472