MachineBasicBlock.h revision 81bf03eb5cd68243eabb52505105aa5f4a831bf3
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 BasicBlock; 23class MachineFunction; 24class MCSymbol; 25class StringRef; 26class raw_ostream; 27 28template <> 29struct ilist_traits<MachineInstr> : public ilist_default_traits<MachineInstr> { 30private: 31 mutable ilist_half_node<MachineInstr> Sentinel; 32 33 // this is only set by the MachineBasicBlock owning the LiveList 34 friend class MachineBasicBlock; 35 MachineBasicBlock* Parent; 36 37public: 38 MachineInstr *createSentinel() const { 39 return static_cast<MachineInstr*>(&Sentinel); 40 } 41 void destroySentinel(MachineInstr *) const {} 42 43 MachineInstr *provideInitialHead() const { return createSentinel(); } 44 MachineInstr *ensureHead(MachineInstr*) const { return createSentinel(); } 45 static void noteHead(MachineInstr*, MachineInstr*) {} 46 47 void addNodeToList(MachineInstr* N); 48 void removeNodeFromList(MachineInstr* N); 49 void transferNodesFromList(ilist_traits &SrcTraits, 50 ilist_iterator<MachineInstr> first, 51 ilist_iterator<MachineInstr> last); 52 void deleteNode(MachineInstr *N); 53private: 54 void createNode(const MachineInstr &); 55}; 56 57class MachineBasicBlock : public ilist_node<MachineBasicBlock> { 58 typedef ilist<MachineInstr> Instructions; 59 Instructions Insts; 60 const BasicBlock *BB; 61 int Number; 62 MachineFunction *xParent; 63 64 /// Predecessors/Successors - Keep track of the predecessor / successor 65 /// basicblocks. 66 std::vector<MachineBasicBlock *> Predecessors; 67 std::vector<MachineBasicBlock *> Successors; 68 69 /// LiveIns - Keep track of the physical registers that are livein of 70 /// the basicblock. 71 std::vector<unsigned> LiveIns; 72 73 /// Alignment - Alignment of the basic block. Zero if the basic block does 74 /// not need to be aligned. 75 unsigned Alignment; 76 77 /// IsLandingPad - Indicate that this basic block is entered via an 78 /// exception handler. 79 bool IsLandingPad; 80 81 /// AddressTaken - Indicate that this basic block is potentially the 82 /// target of an indirect branch. 83 bool AddressTaken; 84 85 // Intrusive list support 86 MachineBasicBlock() {} 87 88 explicit MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb); 89 90 ~MachineBasicBlock(); 91 92 // MachineBasicBlocks are allocated and owned by MachineFunction. 93 friend class MachineFunction; 94 95public: 96 /// getBasicBlock - Return the LLVM basic block that this instance 97 /// corresponded to originally. Note that this may be NULL if this instance 98 /// does not correspond directly to an LLVM basic block. 99 /// 100 const BasicBlock *getBasicBlock() const { return BB; } 101 102 /// getName - Return the name of the corresponding LLVM basic block, or 103 /// "(null)". 104 StringRef getName() const; 105 106 /// hasAddressTaken - Test whether this block is potentially the target 107 /// of an indirect branch. 108 bool hasAddressTaken() const { return AddressTaken; } 109 110 /// setHasAddressTaken - Set this block to reflect that it potentially 111 /// is the target of an indirect branch. 112 void setHasAddressTaken() { AddressTaken = true; } 113 114 /// getParent - Return the MachineFunction containing this basic block. 115 /// 116 const MachineFunction *getParent() const { return xParent; } 117 MachineFunction *getParent() { return xParent; } 118 119 typedef Instructions::iterator iterator; 120 typedef Instructions::const_iterator const_iterator; 121 typedef std::reverse_iterator<const_iterator> const_reverse_iterator; 122 typedef std::reverse_iterator<iterator> reverse_iterator; 123 124 unsigned size() const { return (unsigned)Insts.size(); } 125 bool empty() const { return Insts.empty(); } 126 127 MachineInstr& front() { return Insts.front(); } 128 MachineInstr& back() { return Insts.back(); } 129 const MachineInstr& front() const { return Insts.front(); } 130 const MachineInstr& back() const { return Insts.back(); } 131 132 iterator begin() { return Insts.begin(); } 133 const_iterator begin() const { return Insts.begin(); } 134 iterator end() { return Insts.end(); } 135 const_iterator end() const { return Insts.end(); } 136 reverse_iterator rbegin() { return Insts.rbegin(); } 137 const_reverse_iterator rbegin() const { return Insts.rbegin(); } 138 reverse_iterator rend () { return Insts.rend(); } 139 const_reverse_iterator rend () const { return Insts.rend(); } 140 141 // Machine-CFG iterators 142 typedef std::vector<MachineBasicBlock *>::iterator pred_iterator; 143 typedef std::vector<MachineBasicBlock *>::const_iterator const_pred_iterator; 144 typedef std::vector<MachineBasicBlock *>::iterator succ_iterator; 145 typedef std::vector<MachineBasicBlock *>::const_iterator const_succ_iterator; 146 typedef std::vector<MachineBasicBlock *>::reverse_iterator 147 pred_reverse_iterator; 148 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator 149 const_pred_reverse_iterator; 150 typedef std::vector<MachineBasicBlock *>::reverse_iterator 151 succ_reverse_iterator; 152 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator 153 const_succ_reverse_iterator; 154 155 pred_iterator pred_begin() { return Predecessors.begin(); } 156 const_pred_iterator pred_begin() const { return Predecessors.begin(); } 157 pred_iterator pred_end() { return Predecessors.end(); } 158 const_pred_iterator pred_end() const { return Predecessors.end(); } 159 pred_reverse_iterator pred_rbegin() 160 { return Predecessors.rbegin();} 161 const_pred_reverse_iterator pred_rbegin() const 162 { return Predecessors.rbegin();} 163 pred_reverse_iterator pred_rend() 164 { return Predecessors.rend(); } 165 const_pred_reverse_iterator pred_rend() const 166 { return Predecessors.rend(); } 167 unsigned pred_size() const { 168 return (unsigned)Predecessors.size(); 169 } 170 bool pred_empty() const { return Predecessors.empty(); } 171 succ_iterator succ_begin() { return Successors.begin(); } 172 const_succ_iterator succ_begin() const { return Successors.begin(); } 173 succ_iterator succ_end() { return Successors.end(); } 174 const_succ_iterator succ_end() const { return Successors.end(); } 175 succ_reverse_iterator succ_rbegin() 176 { return Successors.rbegin(); } 177 const_succ_reverse_iterator succ_rbegin() const 178 { return Successors.rbegin(); } 179 succ_reverse_iterator succ_rend() 180 { return Successors.rend(); } 181 const_succ_reverse_iterator succ_rend() const 182 { return Successors.rend(); } 183 unsigned succ_size() const { 184 return (unsigned)Successors.size(); 185 } 186 bool succ_empty() const { return Successors.empty(); } 187 188 // LiveIn management methods. 189 190 /// addLiveIn - Add the specified register as a live in. Note that it 191 /// is an error to add the same register to the same set more than once. 192 void addLiveIn(unsigned Reg) { LiveIns.push_back(Reg); } 193 194 /// removeLiveIn - Remove the specified register from the live in set. 195 /// 196 void removeLiveIn(unsigned Reg); 197 198 /// isLiveIn - Return true if the specified register is in the live in set. 199 /// 200 bool isLiveIn(unsigned Reg) const; 201 202 // Iteration support for live in sets. These sets are kept in sorted 203 // order by their register number. 204 typedef std::vector<unsigned>::const_iterator livein_iterator; 205 livein_iterator livein_begin() const { return LiveIns.begin(); } 206 livein_iterator livein_end() const { return LiveIns.end(); } 207 bool livein_empty() const { return LiveIns.empty(); } 208 209 /// getAlignment - Return alignment of the basic block. 210 /// 211 unsigned getAlignment() const { return Alignment; } 212 213 /// setAlignment - Set alignment of the basic block. 214 /// 215 void setAlignment(unsigned Align) { Alignment = Align; } 216 217 /// isLandingPad - Returns true if the block is a landing pad. That is 218 /// this basic block is entered via an exception handler. 219 bool isLandingPad() const { return IsLandingPad; } 220 221 /// setIsLandingPad - Indicates the block is a landing pad. That is 222 /// this basic block is entered via an exception handler. 223 void setIsLandingPad() { IsLandingPad = true; } 224 225 // Code Layout methods. 226 227 /// moveBefore/moveAfter - move 'this' block before or after the specified 228 /// block. This only moves the block, it does not modify the CFG or adjust 229 /// potential fall-throughs at the end of the block. 230 void moveBefore(MachineBasicBlock *NewAfter); 231 void moveAfter(MachineBasicBlock *NewBefore); 232 233 /// updateTerminator - Update the terminator instructions in block to account 234 /// for changes to the layout. If the block previously used a fallthrough, 235 /// it may now need a branch, and if it previously used branching it may now 236 /// be able to use a fallthrough. 237 void updateTerminator(); 238 239 // Machine-CFG mutators 240 241 /// addSuccessor - Add succ as a successor of this MachineBasicBlock. 242 /// The Predecessors list of succ is automatically updated. 243 /// 244 void addSuccessor(MachineBasicBlock *succ); 245 246 /// removeSuccessor - Remove successor from the successors list of this 247 /// MachineBasicBlock. The Predecessors list of succ is automatically updated. 248 /// 249 void removeSuccessor(MachineBasicBlock *succ); 250 251 /// removeSuccessor - Remove specified successor from the successors list of 252 /// this MachineBasicBlock. The Predecessors list of succ is automatically 253 /// updated. Return the iterator to the element after the one removed. 254 /// 255 succ_iterator removeSuccessor(succ_iterator I); 256 257 /// transferSuccessors - Transfers all the successors from MBB to this 258 /// machine basic block (i.e., copies all the successors fromMBB and 259 /// remove all the successors from fromMBB). 260 void transferSuccessors(MachineBasicBlock *fromMBB); 261 262 /// isSuccessor - Return true if the specified MBB is a successor of this 263 /// block. 264 bool isSuccessor(const MachineBasicBlock *MBB) const; 265 266 /// isLayoutSuccessor - Return true if the specified MBB will be emitted 267 /// immediately after this block, such that if this block exits by 268 /// falling through, control will transfer to the specified MBB. Note 269 /// that MBB need not be a successor at all, for example if this block 270 /// ends with an unconditional branch to some other block. 271 bool isLayoutSuccessor(const MachineBasicBlock *MBB) const; 272 273 /// canFallThrough - Return true if the block can implicitly transfer 274 /// control to the block after it by falling off the end of it. This should 275 /// return false if it can reach the block after it, but it uses an explicit 276 /// branch to do so (e.g., a table jump). True is a conservative answer. 277 bool canFallThrough(); 278 279 /// getFirstTerminator - returns an iterator to the first terminator 280 /// instruction of this basic block. If a terminator does not exist, 281 /// it returns end() 282 iterator getFirstTerminator(); 283 284 void pop_front() { Insts.pop_front(); } 285 void pop_back() { Insts.pop_back(); } 286 void push_back(MachineInstr *MI) { Insts.push_back(MI); } 287 template<typename IT> 288 void insert(iterator I, IT S, IT E) { Insts.insert(I, S, E); } 289 iterator insert(iterator I, MachineInstr *M) { return Insts.insert(I, M); } 290 291 // erase - Remove the specified element or range from the instruction list. 292 // These functions delete any instructions removed. 293 // 294 iterator erase(iterator I) { return Insts.erase(I); } 295 iterator erase(iterator I, iterator E) { return Insts.erase(I, E); } 296 MachineInstr *remove(MachineInstr *I) { return Insts.remove(I); } 297 void clear() { Insts.clear(); } 298 299 /// splice - Take an instruction from MBB 'Other' at the position From, 300 /// and insert it into this MBB right before 'where'. 301 void splice(iterator where, MachineBasicBlock *Other, iterator From) { 302 Insts.splice(where, Other->Insts, From); 303 } 304 305 /// splice - Take a block of instructions from MBB 'Other' in the range [From, 306 /// To), and insert them into this MBB right before 'where'. 307 void splice(iterator where, MachineBasicBlock *Other, iterator From, 308 iterator To) { 309 Insts.splice(where, Other->Insts, From, To); 310 } 311 312 /// removeFromParent - This method unlinks 'this' from the containing 313 /// function, and returns it, but does not delete it. 314 MachineBasicBlock *removeFromParent(); 315 316 /// eraseFromParent - This method unlinks 'this' from the containing 317 /// function and deletes it. 318 void eraseFromParent(); 319 320 /// ReplaceUsesOfBlockWith - Given a machine basic block that branched to 321 /// 'Old', change the code and CFG so that it branches to 'New' instead. 322 void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New); 323 324 /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in 325 /// the CFG to be inserted. If we have proven that MBB can only branch to 326 /// DestA and DestB, remove any other MBB successors from the CFG. DestA and 327 /// DestB can be null. Besides DestA and DestB, retain other edges leading 328 /// to LandingPads (currently there can be only one; we don't check or require 329 /// that here). Note it is possible that DestA and/or DestB are LandingPads. 330 bool CorrectExtraCFGEdges(MachineBasicBlock *DestA, 331 MachineBasicBlock *DestB, 332 bool isCond); 333 334 /// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping 335 /// any DBG_VALUE instructions. Return UnknownLoc if there is none. 336 DebugLoc findDebugLoc(MachineBasicBlock::iterator &MBBI); 337 338 // Debugging methods. 339 void dump() const; 340 void print(raw_ostream &OS) const; 341 342 /// getNumber - MachineBasicBlocks are uniquely numbered at the function 343 /// level, unless they're not in a MachineFunction yet, in which case this 344 /// will return -1. 345 /// 346 int getNumber() const { return Number; } 347 void setNumber(int N) { Number = N; } 348 349 /// getSymbol - Return the MCSymbol for this basic block. 350 /// 351 MCSymbol *getSymbol() const; 352 353private: // Methods used to maintain doubly linked list of blocks... 354 friend struct ilist_traits<MachineBasicBlock>; 355 356 // Machine-CFG mutators 357 358 /// addPredecessor - Remove pred as a predecessor of this MachineBasicBlock. 359 /// Don't do this unless you know what you're doing, because it doesn't 360 /// update pred's successors list. Use pred->addSuccessor instead. 361 /// 362 void addPredecessor(MachineBasicBlock *pred); 363 364 /// removePredecessor - Remove pred as a predecessor of this 365 /// MachineBasicBlock. Don't do this unless you know what you're 366 /// doing, because it doesn't update pred's successors list. Use 367 /// pred->removeSuccessor instead. 368 /// 369 void removePredecessor(MachineBasicBlock *pred); 370}; 371 372raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB); 373 374void WriteAsOperand(raw_ostream &, const MachineBasicBlock*, bool t); 375 376//===--------------------------------------------------------------------===// 377// GraphTraits specializations for machine basic block graphs (machine-CFGs) 378//===--------------------------------------------------------------------===// 379 380// Provide specializations of GraphTraits to be able to treat a 381// MachineFunction as a graph of MachineBasicBlocks... 382// 383 384template <> struct GraphTraits<MachineBasicBlock *> { 385 typedef MachineBasicBlock NodeType; 386 typedef MachineBasicBlock::succ_iterator ChildIteratorType; 387 388 static NodeType *getEntryNode(MachineBasicBlock *BB) { return BB; } 389 static inline ChildIteratorType child_begin(NodeType *N) { 390 return N->succ_begin(); 391 } 392 static inline ChildIteratorType child_end(NodeType *N) { 393 return N->succ_end(); 394 } 395}; 396 397template <> struct GraphTraits<const MachineBasicBlock *> { 398 typedef const MachineBasicBlock NodeType; 399 typedef MachineBasicBlock::const_succ_iterator ChildIteratorType; 400 401 static NodeType *getEntryNode(const MachineBasicBlock *BB) { return BB; } 402 static inline ChildIteratorType child_begin(NodeType *N) { 403 return N->succ_begin(); 404 } 405 static inline ChildIteratorType child_end(NodeType *N) { 406 return N->succ_end(); 407 } 408}; 409 410// Provide specializations of GraphTraits to be able to treat a 411// MachineFunction as a graph of MachineBasicBlocks... and to walk it 412// in inverse order. Inverse order for a function is considered 413// to be when traversing the predecessor edges of a MBB 414// instead of the successor edges. 415// 416template <> struct GraphTraits<Inverse<MachineBasicBlock*> > { 417 typedef MachineBasicBlock NodeType; 418 typedef MachineBasicBlock::pred_iterator ChildIteratorType; 419 static NodeType *getEntryNode(Inverse<MachineBasicBlock *> G) { 420 return G.Graph; 421 } 422 static inline ChildIteratorType child_begin(NodeType *N) { 423 return N->pred_begin(); 424 } 425 static inline ChildIteratorType child_end(NodeType *N) { 426 return N->pred_end(); 427 } 428}; 429 430template <> struct GraphTraits<Inverse<const MachineBasicBlock*> > { 431 typedef const MachineBasicBlock NodeType; 432 typedef MachineBasicBlock::const_pred_iterator ChildIteratorType; 433 static NodeType *getEntryNode(Inverse<const MachineBasicBlock*> G) { 434 return G.Graph; 435 } 436 static inline ChildIteratorType child_begin(NodeType *N) { 437 return N->pred_begin(); 438 } 439 static inline ChildIteratorType child_end(NodeType *N) { 440 return N->pred_end(); 441 } 442}; 443 444} // End llvm namespace 445 446#endif 447