MachineBasicBlock.h revision 13ba2dab631636e525a44bb259aaea56a860d1c7
1//===-- llvm/CodeGen/MachineBasicBlock.h ------------------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// Collect the sequence of machine instructions for a basic block. 11// 12//===----------------------------------------------------------------------===// 13 14#ifndef LLVM_CODEGEN_MACHINEBASICBLOCK_H 15#define LLVM_CODEGEN_MACHINEBASICBLOCK_H 16 17#include "llvm/CodeGen/MachineInstr.h" 18#include "llvm/ADT/GraphTraits.h" 19#include <functional> 20 21namespace llvm { 22 23class Pass; 24class BasicBlock; 25class MachineFunction; 26class MCSymbol; 27class SlotIndexes; 28class StringRef; 29class raw_ostream; 30 31template <> 32struct ilist_traits<MachineInstr> : public ilist_default_traits<MachineInstr> { 33private: 34 mutable ilist_half_node<MachineInstr> Sentinel; 35 36 // this is only set by the MachineBasicBlock owning the LiveList 37 friend class MachineBasicBlock; 38 MachineBasicBlock* Parent; 39 40public: 41 MachineInstr *createSentinel() const { 42 return static_cast<MachineInstr*>(&Sentinel); 43 } 44 void destroySentinel(MachineInstr *) const {} 45 46 MachineInstr *provideInitialHead() const { return createSentinel(); } 47 MachineInstr *ensureHead(MachineInstr*) const { return createSentinel(); } 48 static void noteHead(MachineInstr*, MachineInstr*) {} 49 50 void addNodeToList(MachineInstr* N); 51 void removeNodeFromList(MachineInstr* N); 52 void transferNodesFromList(ilist_traits &SrcTraits, 53 ilist_iterator<MachineInstr> first, 54 ilist_iterator<MachineInstr> last); 55 void deleteNode(MachineInstr *N); 56private: 57 void createNode(const MachineInstr &); 58}; 59 60class MachineBasicBlock : public ilist_node<MachineBasicBlock> { 61 typedef ilist<MachineInstr> Instructions; 62 Instructions Insts; 63 const BasicBlock *BB; 64 int Number; 65 MachineFunction *xParent; 66 67 /// Predecessors/Successors - Keep track of the predecessor / successor 68 /// basicblocks. 69 std::vector<MachineBasicBlock *> Predecessors; 70 std::vector<MachineBasicBlock *> Successors; 71 72 /// LiveIns - Keep track of the physical registers that are livein of 73 /// the basicblock. 74 std::vector<unsigned> LiveIns; 75 76 /// Alignment - Alignment of the basic block. Zero if the basic block does 77 /// not need to be aligned. 78 unsigned Alignment; 79 80 /// IsLandingPad - Indicate that this basic block is entered via an 81 /// exception handler. 82 bool IsLandingPad; 83 84 /// AddressTaken - Indicate that this basic block is potentially the 85 /// target of an indirect branch. 86 bool AddressTaken; 87 88 // Intrusive list support 89 MachineBasicBlock() {} 90 91 explicit MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb); 92 93 ~MachineBasicBlock(); 94 95 // MachineBasicBlocks are allocated and owned by MachineFunction. 96 friend class MachineFunction; 97 98public: 99 /// getBasicBlock - Return the LLVM basic block that this instance 100 /// corresponded to originally. Note that this may be NULL if this instance 101 /// does not correspond directly to an LLVM basic block. 102 /// 103 const BasicBlock *getBasicBlock() const { return BB; } 104 105 /// getName - Return the name of the corresponding LLVM basic block, or 106 /// "(null)". 107 StringRef getName() const; 108 109 /// hasAddressTaken - Test whether this block is potentially the target 110 /// of an indirect branch. 111 bool hasAddressTaken() const { return AddressTaken; } 112 113 /// setHasAddressTaken - Set this block to reflect that it potentially 114 /// is the target of an indirect branch. 115 void setHasAddressTaken() { AddressTaken = true; } 116 117 /// getParent - Return the MachineFunction containing this basic block. 118 /// 119 const MachineFunction *getParent() const { return xParent; } 120 MachineFunction *getParent() { return xParent; } 121 122 typedef Instructions::iterator iterator; 123 typedef Instructions::const_iterator const_iterator; 124 typedef std::reverse_iterator<const_iterator> const_reverse_iterator; 125 typedef std::reverse_iterator<iterator> reverse_iterator; 126 127 unsigned size() const { return (unsigned)Insts.size(); } 128 bool empty() const { return Insts.empty(); } 129 130 MachineInstr& front() { return Insts.front(); } 131 MachineInstr& back() { return Insts.back(); } 132 const MachineInstr& front() const { return Insts.front(); } 133 const MachineInstr& back() const { return Insts.back(); } 134 135 iterator begin() { return Insts.begin(); } 136 const_iterator begin() const { return Insts.begin(); } 137 iterator end() { return Insts.end(); } 138 const_iterator end() const { return Insts.end(); } 139 reverse_iterator rbegin() { return Insts.rbegin(); } 140 const_reverse_iterator rbegin() const { return Insts.rbegin(); } 141 reverse_iterator rend () { return Insts.rend(); } 142 const_reverse_iterator rend () const { return Insts.rend(); } 143 144 // Machine-CFG iterators 145 typedef std::vector<MachineBasicBlock *>::iterator pred_iterator; 146 typedef std::vector<MachineBasicBlock *>::const_iterator const_pred_iterator; 147 typedef std::vector<MachineBasicBlock *>::iterator succ_iterator; 148 typedef std::vector<MachineBasicBlock *>::const_iterator const_succ_iterator; 149 typedef std::vector<MachineBasicBlock *>::reverse_iterator 150 pred_reverse_iterator; 151 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator 152 const_pred_reverse_iterator; 153 typedef std::vector<MachineBasicBlock *>::reverse_iterator 154 succ_reverse_iterator; 155 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator 156 const_succ_reverse_iterator; 157 158 pred_iterator pred_begin() { return Predecessors.begin(); } 159 const_pred_iterator pred_begin() const { return Predecessors.begin(); } 160 pred_iterator pred_end() { return Predecessors.end(); } 161 const_pred_iterator pred_end() const { return Predecessors.end(); } 162 pred_reverse_iterator pred_rbegin() 163 { return Predecessors.rbegin();} 164 const_pred_reverse_iterator pred_rbegin() const 165 { return Predecessors.rbegin();} 166 pred_reverse_iterator pred_rend() 167 { return Predecessors.rend(); } 168 const_pred_reverse_iterator pred_rend() const 169 { return Predecessors.rend(); } 170 unsigned pred_size() const { 171 return (unsigned)Predecessors.size(); 172 } 173 bool pred_empty() const { return Predecessors.empty(); } 174 succ_iterator succ_begin() { return Successors.begin(); } 175 const_succ_iterator succ_begin() const { return Successors.begin(); } 176 succ_iterator succ_end() { return Successors.end(); } 177 const_succ_iterator succ_end() const { return Successors.end(); } 178 succ_reverse_iterator succ_rbegin() 179 { return Successors.rbegin(); } 180 const_succ_reverse_iterator succ_rbegin() const 181 { return Successors.rbegin(); } 182 succ_reverse_iterator succ_rend() 183 { return Successors.rend(); } 184 const_succ_reverse_iterator succ_rend() const 185 { return Successors.rend(); } 186 unsigned succ_size() const { 187 return (unsigned)Successors.size(); 188 } 189 bool succ_empty() const { return Successors.empty(); } 190 191 // LiveIn management methods. 192 193 /// addLiveIn - Add the specified register as a live in. Note that it 194 /// is an error to add the same register to the same set more than once. 195 void addLiveIn(unsigned Reg) { LiveIns.push_back(Reg); } 196 197 /// removeLiveIn - Remove the specified register from the live in set. 198 /// 199 void removeLiveIn(unsigned Reg); 200 201 /// isLiveIn - Return true if the specified register is in the live in set. 202 /// 203 bool isLiveIn(unsigned Reg) const; 204 205 // Iteration support for live in sets. These sets are kept in sorted 206 // order by their register number. 207 typedef std::vector<unsigned>::const_iterator livein_iterator; 208 livein_iterator livein_begin() const { return LiveIns.begin(); } 209 livein_iterator livein_end() const { return LiveIns.end(); } 210 bool livein_empty() const { return LiveIns.empty(); } 211 212 /// getAlignment - Return alignment of the basic block. 213 /// 214 unsigned getAlignment() const { return Alignment; } 215 216 /// setAlignment - Set alignment of the basic block. 217 /// 218 void setAlignment(unsigned Align) { Alignment = Align; } 219 220 /// isLandingPad - Returns true if the block is a landing pad. That is 221 /// this basic block is entered via an exception handler. 222 bool isLandingPad() const { return IsLandingPad; } 223 224 /// setIsLandingPad - Indicates the block is a landing pad. That is 225 /// this basic block is entered via an exception handler. 226 void setIsLandingPad() { IsLandingPad = true; } 227 228 /// getLandingPadSuccessor - If this block has a successor that is a landing 229 /// pad, return it. Otherwise return NULL. 230 const MachineBasicBlock *getLandingPadSuccessor() const; 231 232 // Code Layout methods. 233 234 /// moveBefore/moveAfter - move 'this' block before or after the specified 235 /// block. This only moves the block, it does not modify the CFG or adjust 236 /// potential fall-throughs at the end of the block. 237 void moveBefore(MachineBasicBlock *NewAfter); 238 void moveAfter(MachineBasicBlock *NewBefore); 239 240 /// updateTerminator - Update the terminator instructions in block to account 241 /// for changes to the layout. If the block previously used a fallthrough, 242 /// it may now need a branch, and if it previously used branching it may now 243 /// be able to use a fallthrough. 244 void updateTerminator(); 245 246 // Machine-CFG mutators 247 248 /// addSuccessor - Add succ as a successor of this MachineBasicBlock. 249 /// The Predecessors list of succ is automatically updated. 250 /// 251 void addSuccessor(MachineBasicBlock *succ); 252 253 /// removeSuccessor - Remove successor from the successors list of this 254 /// MachineBasicBlock. The Predecessors list of succ is automatically updated. 255 /// 256 void removeSuccessor(MachineBasicBlock *succ); 257 258 /// removeSuccessor - Remove specified successor from the successors list of 259 /// this MachineBasicBlock. The Predecessors list of succ is automatically 260 /// updated. Return the iterator to the element after the one removed. 261 /// 262 succ_iterator removeSuccessor(succ_iterator I); 263 264 /// transferSuccessors - Transfers all the successors from MBB to this 265 /// machine basic block (i.e., copies all the successors fromMBB and 266 /// remove all the successors from fromMBB). 267 void transferSuccessors(MachineBasicBlock *fromMBB); 268 269 /// transferSuccessorsAndUpdatePHIs - Transfers all the successors, as 270 /// in transferSuccessors, and update PHI operands in the successor blocks 271 /// which refer to fromMBB to refer to this. 272 void transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB); 273 274 /// isSuccessor - Return true if the specified MBB is a successor of this 275 /// block. 276 bool isSuccessor(const MachineBasicBlock *MBB) const; 277 278 /// isLayoutSuccessor - Return true if the specified MBB will be emitted 279 /// immediately after this block, such that if this block exits by 280 /// falling through, control will transfer to the specified MBB. Note 281 /// that MBB need not be a successor at all, for example if this block 282 /// ends with an unconditional branch to some other block. 283 bool isLayoutSuccessor(const MachineBasicBlock *MBB) const; 284 285 /// canFallThrough - Return true if the block can implicitly transfer 286 /// control to the block after it by falling off the end of it. This should 287 /// return false if it can reach the block after it, but it uses an explicit 288 /// branch to do so (e.g., a table jump). True is a conservative answer. 289 bool canFallThrough(); 290 291 /// Returns a pointer to the first instructon in this block that is not a 292 /// PHINode instruction. When adding instruction to the beginning of the 293 /// basic block, they should be added before the returned value, not before 294 /// the first instruction, which might be PHI. 295 /// Returns end() is there's no non-PHI instruction. 296 iterator getFirstNonPHI(); 297 298 /// SkipPHIsAndLabels - Return the first instruction in MBB after I that is 299 /// not a PHI or a label. This is the correct point to insert copies at the 300 /// beginning of a basic block. 301 iterator SkipPHIsAndLabels(iterator I); 302 303 /// getFirstTerminator - returns an iterator to the first terminator 304 /// instruction of this basic block. If a terminator does not exist, 305 /// it returns end() 306 iterator getFirstTerminator(); 307 308 /// getLastNonDebugInstr - returns an iterator to the last non-debug 309 /// instruction in the basic block, or end() 310 iterator getLastNonDebugInstr(); 311 312 /// SplitCriticalEdge - Split the critical edge from this block to the 313 /// given successor block, and return the newly created block, or null 314 /// if splitting is not possible. 315 /// 316 /// This function updates LiveVariables, MachineDominatorTree, and 317 /// MachineLoopInfo, as applicable. 318 MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P); 319 320 void pop_front() { Insts.pop_front(); } 321 void pop_back() { Insts.pop_back(); } 322 void push_back(MachineInstr *MI) { Insts.push_back(MI); } 323 template<typename IT> 324 void insert(iterator I, IT S, IT E) { Insts.insert(I, S, E); } 325 iterator insert(iterator I, MachineInstr *M) { return Insts.insert(I, M); } 326 iterator insertAfter(iterator I, MachineInstr *M) { 327 return Insts.insertAfter(I, M); 328 } 329 330 // erase - Remove the specified element or range from the instruction list. 331 // These functions delete any instructions removed. 332 // 333 iterator erase(iterator I) { return Insts.erase(I); } 334 iterator erase(iterator I, iterator E) { return Insts.erase(I, E); } 335 MachineInstr *remove(MachineInstr *I) { return Insts.remove(I); } 336 void clear() { Insts.clear(); } 337 338 /// splice - Take an instruction from MBB 'Other' at the position From, 339 /// and insert it into this MBB right before 'where'. 340 void splice(iterator where, MachineBasicBlock *Other, iterator From) { 341 Insts.splice(where, Other->Insts, From); 342 } 343 344 /// splice - Take a block of instructions from MBB 'Other' in the range [From, 345 /// To), and insert them into this MBB right before 'where'. 346 void splice(iterator where, MachineBasicBlock *Other, iterator From, 347 iterator To) { 348 Insts.splice(where, Other->Insts, From, To); 349 } 350 351 /// removeFromParent - This method unlinks 'this' from the containing 352 /// function, and returns it, but does not delete it. 353 MachineBasicBlock *removeFromParent(); 354 355 /// eraseFromParent - This method unlinks 'this' from the containing 356 /// function and deletes it. 357 void eraseFromParent(); 358 359 /// ReplaceUsesOfBlockWith - Given a machine basic block that branched to 360 /// 'Old', change the code and CFG so that it branches to 'New' instead. 361 void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New); 362 363 /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in 364 /// the CFG to be inserted. If we have proven that MBB can only branch to 365 /// DestA and DestB, remove any other MBB successors from the CFG. DestA and 366 /// DestB can be null. Besides DestA and DestB, retain other edges leading 367 /// to LandingPads (currently there can be only one; we don't check or require 368 /// that here). Note it is possible that DestA and/or DestB are LandingPads. 369 bool CorrectExtraCFGEdges(MachineBasicBlock *DestA, 370 MachineBasicBlock *DestB, 371 bool isCond); 372 373 /// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping 374 /// any DBG_VALUE instructions. Return UnknownLoc if there is none. 375 DebugLoc findDebugLoc(MachineBasicBlock::iterator &MBBI); 376 377 // Debugging methods. 378 void dump() const; 379 void print(raw_ostream &OS, SlotIndexes* = 0) const; 380 381 /// getNumber - MachineBasicBlocks are uniquely numbered at the function 382 /// level, unless they're not in a MachineFunction yet, in which case this 383 /// will return -1. 384 /// 385 int getNumber() const { return Number; } 386 void setNumber(int N) { Number = N; } 387 388 /// getSymbol - Return the MCSymbol for this basic block. 389 /// 390 MCSymbol *getSymbol() const; 391 392private: // Methods used to maintain doubly linked list of blocks... 393 friend struct ilist_traits<MachineBasicBlock>; 394 395 // Machine-CFG mutators 396 397 /// addPredecessor - Remove pred as a predecessor of this MachineBasicBlock. 398 /// Don't do this unless you know what you're doing, because it doesn't 399 /// update pred's successors list. Use pred->addSuccessor instead. 400 /// 401 void addPredecessor(MachineBasicBlock *pred); 402 403 /// removePredecessor - Remove pred as a predecessor of this 404 /// MachineBasicBlock. Don't do this unless you know what you're 405 /// doing, because it doesn't update pred's successors list. Use 406 /// pred->removeSuccessor instead. 407 /// 408 void removePredecessor(MachineBasicBlock *pred); 409}; 410 411raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB); 412 413void WriteAsOperand(raw_ostream &, const MachineBasicBlock*, bool t); 414 415// This is useful when building IndexedMaps keyed on basic block pointers. 416struct MBB2NumberFunctor : 417 public std::unary_function<const MachineBasicBlock*, unsigned> { 418 unsigned operator()(const MachineBasicBlock *MBB) const { 419 return MBB->getNumber(); 420 } 421}; 422 423//===--------------------------------------------------------------------===// 424// GraphTraits specializations for machine basic block graphs (machine-CFGs) 425//===--------------------------------------------------------------------===// 426 427// Provide specializations of GraphTraits to be able to treat a 428// MachineFunction as a graph of MachineBasicBlocks... 429// 430 431template <> struct GraphTraits<MachineBasicBlock *> { 432 typedef MachineBasicBlock NodeType; 433 typedef MachineBasicBlock::succ_iterator ChildIteratorType; 434 435 static NodeType *getEntryNode(MachineBasicBlock *BB) { return BB; } 436 static inline ChildIteratorType child_begin(NodeType *N) { 437 return N->succ_begin(); 438 } 439 static inline ChildIteratorType child_end(NodeType *N) { 440 return N->succ_end(); 441 } 442}; 443 444template <> struct GraphTraits<const MachineBasicBlock *> { 445 typedef const MachineBasicBlock NodeType; 446 typedef MachineBasicBlock::const_succ_iterator ChildIteratorType; 447 448 static NodeType *getEntryNode(const MachineBasicBlock *BB) { return BB; } 449 static inline ChildIteratorType child_begin(NodeType *N) { 450 return N->succ_begin(); 451 } 452 static inline ChildIteratorType child_end(NodeType *N) { 453 return N->succ_end(); 454 } 455}; 456 457// Provide specializations of GraphTraits to be able to treat a 458// MachineFunction as a graph of MachineBasicBlocks... and to walk it 459// in inverse order. Inverse order for a function is considered 460// to be when traversing the predecessor edges of a MBB 461// instead of the successor edges. 462// 463template <> struct GraphTraits<Inverse<MachineBasicBlock*> > { 464 typedef MachineBasicBlock NodeType; 465 typedef MachineBasicBlock::pred_iterator ChildIteratorType; 466 static NodeType *getEntryNode(Inverse<MachineBasicBlock *> G) { 467 return G.Graph; 468 } 469 static inline ChildIteratorType child_begin(NodeType *N) { 470 return N->pred_begin(); 471 } 472 static inline ChildIteratorType child_end(NodeType *N) { 473 return N->pred_end(); 474 } 475}; 476 477template <> struct GraphTraits<Inverse<const MachineBasicBlock*> > { 478 typedef const MachineBasicBlock NodeType; 479 typedef MachineBasicBlock::const_pred_iterator ChildIteratorType; 480 static NodeType *getEntryNode(Inverse<const MachineBasicBlock*> G) { 481 return G.Graph; 482 } 483 static inline ChildIteratorType child_begin(NodeType *N) { 484 return N->pred_begin(); 485 } 486 static inline ChildIteratorType child_end(NodeType *N) { 487 return N->pred_end(); 488 } 489}; 490 491} // End llvm namespace 492 493#endif 494