MachineBasicBlock.h revision 205218
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>::iterator livein_iterator; 205 typedef std::vector<unsigned>::const_iterator const_livein_iterator; 206 livein_iterator livein_begin() { return LiveIns.begin(); } 207 const_livein_iterator livein_begin() const { return LiveIns.begin(); } 208 livein_iterator livein_end() { return LiveIns.end(); } 209 const_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 // Code Layout methods. 229 230 /// moveBefore/moveAfter - move 'this' block before or after the specified 231 /// block. This only moves the block, it does not modify the CFG or adjust 232 /// potential fall-throughs at the end of the block. 233 void moveBefore(MachineBasicBlock *NewAfter); 234 void moveAfter(MachineBasicBlock *NewBefore); 235 236 /// updateTerminator - Update the terminator instructions in block to account 237 /// for changes to the layout. If the block previously used a fallthrough, 238 /// it may now need a branch, and if it previously used branching it may now 239 /// be able to use a fallthrough. 240 void updateTerminator(); 241 242 // Machine-CFG mutators 243 244 /// addSuccessor - Add succ as a successor of this MachineBasicBlock. 245 /// The Predecessors list of succ is automatically updated. 246 /// 247 void addSuccessor(MachineBasicBlock *succ); 248 249 /// removeSuccessor - Remove successor from the successors list of this 250 /// MachineBasicBlock. The Predecessors list of succ is automatically updated. 251 /// 252 void removeSuccessor(MachineBasicBlock *succ); 253 254 /// removeSuccessor - Remove specified successor from the successors list of 255 /// this MachineBasicBlock. The Predecessors list of succ is automatically 256 /// updated. Return the iterator to the element after the one removed. 257 /// 258 succ_iterator removeSuccessor(succ_iterator I); 259 260 /// transferSuccessors - Transfers all the successors from MBB to this 261 /// machine basic block (i.e., copies all the successors fromMBB and 262 /// remove all the successors from fromMBB). 263 void transferSuccessors(MachineBasicBlock *fromMBB); 264 265 /// isSuccessor - Return true if the specified MBB is a successor of this 266 /// block. 267 bool isSuccessor(const MachineBasicBlock *MBB) const; 268 269 /// isLayoutSuccessor - Return true if the specified MBB will be emitted 270 /// immediately after this block, such that if this block exits by 271 /// falling through, control will transfer to the specified MBB. Note 272 /// that MBB need not be a successor at all, for example if this block 273 /// ends with an unconditional branch to some other block. 274 bool isLayoutSuccessor(const MachineBasicBlock *MBB) const; 275 276 /// canFallThrough - Return true if the block can implicitly transfer 277 /// control to the block after it by falling off the end of it. This should 278 /// return false if it can reach the block after it, but it uses an explicit 279 /// branch to do so (e.g., a table jump). True is a conservative answer. 280 bool canFallThrough(); 281 282 /// getFirstTerminator - returns an iterator to the first terminator 283 /// instruction of this basic block. If a terminator does not exist, 284 /// it returns end() 285 iterator getFirstTerminator(); 286 287 void pop_front() { Insts.pop_front(); } 288 void pop_back() { Insts.pop_back(); } 289 void push_back(MachineInstr *MI) { Insts.push_back(MI); } 290 template<typename IT> 291 void insert(iterator I, IT S, IT E) { Insts.insert(I, S, E); } 292 iterator insert(iterator I, MachineInstr *M) { return Insts.insert(I, M); } 293 294 // erase - Remove the specified element or range from the instruction list. 295 // These functions delete any instructions removed. 296 // 297 iterator erase(iterator I) { return Insts.erase(I); } 298 iterator erase(iterator I, iterator E) { return Insts.erase(I, E); } 299 MachineInstr *remove(MachineInstr *I) { return Insts.remove(I); } 300 void clear() { Insts.clear(); } 301 302 /// splice - Take an instruction from MBB 'Other' at the position From, 303 /// and insert it into this MBB right before 'where'. 304 void splice(iterator where, MachineBasicBlock *Other, iterator From) { 305 Insts.splice(where, Other->Insts, From); 306 } 307 308 /// splice - Take a block of instructions from MBB 'Other' in the range [From, 309 /// To), and insert them into this MBB right before 'where'. 310 void splice(iterator where, MachineBasicBlock *Other, iterator From, 311 iterator To) { 312 Insts.splice(where, Other->Insts, From, To); 313 } 314 315 /// removeFromParent - This method unlinks 'this' from the containing 316 /// function, and returns it, but does not delete it. 317 MachineBasicBlock *removeFromParent(); 318 319 /// eraseFromParent - This method unlinks 'this' from the containing 320 /// function and deletes it. 321 void eraseFromParent(); 322 323 /// ReplaceUsesOfBlockWith - Given a machine basic block that branched to 324 /// 'Old', change the code and CFG so that it branches to 'New' instead. 325 void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New); 326 327 /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in 328 /// the CFG to be inserted. If we have proven that MBB can only branch to 329 /// DestA and DestB, remove any other MBB successors from the CFG. DestA and 330 /// DestB can be null. Besides DestA and DestB, retain other edges leading 331 /// to LandingPads (currently there can be only one; we don't check or require 332 /// that here). Note it is possible that DestA and/or DestB are LandingPads. 333 bool CorrectExtraCFGEdges(MachineBasicBlock *DestA, 334 MachineBasicBlock *DestB, 335 bool isCond); 336 337 /// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping 338 /// any DBG_VALUE instructions. Return UnknownLoc if there is none. 339 DebugLoc findDebugLoc(MachineBasicBlock::iterator &MBBI); 340 341 // Debugging methods. 342 void dump() const; 343 void print(raw_ostream &OS) const; 344 345 /// getNumber - MachineBasicBlocks are uniquely numbered at the function 346 /// level, unless they're not in a MachineFunction yet, in which case this 347 /// will return -1. 348 /// 349 int getNumber() const { return Number; } 350 void setNumber(int N) { Number = N; } 351 352 /// getSymbol - Return the MCSymbol for this basic block. 353 /// 354 MCSymbol *getSymbol() const; 355 356private: // Methods used to maintain doubly linked list of blocks... 357 friend struct ilist_traits<MachineBasicBlock>; 358 359 // Machine-CFG mutators 360 361 /// addPredecessor - Remove pred as a predecessor of this MachineBasicBlock. 362 /// Don't do this unless you know what you're doing, because it doesn't 363 /// update pred's successors list. Use pred->addSuccessor instead. 364 /// 365 void addPredecessor(MachineBasicBlock *pred); 366 367 /// removePredecessor - Remove pred as a predecessor of this 368 /// MachineBasicBlock. Don't do this unless you know what you're 369 /// doing, because it doesn't update pred's successors list. Use 370 /// pred->removeSuccessor instead. 371 /// 372 void removePredecessor(MachineBasicBlock *pred); 373}; 374 375raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB); 376 377void WriteAsOperand(raw_ostream &, const MachineBasicBlock*, bool t); 378 379//===--------------------------------------------------------------------===// 380// GraphTraits specializations for machine basic block graphs (machine-CFGs) 381//===--------------------------------------------------------------------===// 382 383// Provide specializations of GraphTraits to be able to treat a 384// MachineFunction as a graph of MachineBasicBlocks... 385// 386 387template <> struct GraphTraits<MachineBasicBlock *> { 388 typedef MachineBasicBlock NodeType; 389 typedef MachineBasicBlock::succ_iterator ChildIteratorType; 390 391 static NodeType *getEntryNode(MachineBasicBlock *BB) { return BB; } 392 static inline ChildIteratorType child_begin(NodeType *N) { 393 return N->succ_begin(); 394 } 395 static inline ChildIteratorType child_end(NodeType *N) { 396 return N->succ_end(); 397 } 398}; 399 400template <> struct GraphTraits<const MachineBasicBlock *> { 401 typedef const MachineBasicBlock NodeType; 402 typedef MachineBasicBlock::const_succ_iterator ChildIteratorType; 403 404 static NodeType *getEntryNode(const MachineBasicBlock *BB) { return BB; } 405 static inline ChildIteratorType child_begin(NodeType *N) { 406 return N->succ_begin(); 407 } 408 static inline ChildIteratorType child_end(NodeType *N) { 409 return N->succ_end(); 410 } 411}; 412 413// Provide specializations of GraphTraits to be able to treat a 414// MachineFunction as a graph of MachineBasicBlocks... and to walk it 415// in inverse order. Inverse order for a function is considered 416// to be when traversing the predecessor edges of a MBB 417// instead of the successor edges. 418// 419template <> struct GraphTraits<Inverse<MachineBasicBlock*> > { 420 typedef MachineBasicBlock NodeType; 421 typedef MachineBasicBlock::pred_iterator ChildIteratorType; 422 static NodeType *getEntryNode(Inverse<MachineBasicBlock *> G) { 423 return G.Graph; 424 } 425 static inline ChildIteratorType child_begin(NodeType *N) { 426 return N->pred_begin(); 427 } 428 static inline ChildIteratorType child_end(NodeType *N) { 429 return N->pred_end(); 430 } 431}; 432 433template <> struct GraphTraits<Inverse<const MachineBasicBlock*> > { 434 typedef const MachineBasicBlock NodeType; 435 typedef MachineBasicBlock::const_pred_iterator ChildIteratorType; 436 static NodeType *getEntryNode(Inverse<const MachineBasicBlock*> G) { 437 return G.Graph; 438 } 439 static inline ChildIteratorType child_begin(NodeType *N) { 440 return N->pred_begin(); 441 } 442 static inline ChildIteratorType child_end(NodeType *N) { 443 return N->pred_end(); 444 } 445}; 446 447} // End llvm namespace 448 449#endif 450