MachineBasicBlock.h revision 199989
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 raw_ostream; 25 26template <> 27struct ilist_traits<MachineInstr> : public ilist_default_traits<MachineInstr> { 28private: 29 mutable ilist_half_node<MachineInstr> Sentinel; 30 31 // this is only set by the MachineBasicBlock owning the LiveList 32 friend class MachineBasicBlock; 33 MachineBasicBlock* Parent; 34 35public: 36 MachineInstr *createSentinel() const { 37 return static_cast<MachineInstr*>(&Sentinel); 38 } 39 void destroySentinel(MachineInstr *) const {} 40 41 MachineInstr *provideInitialHead() const { return createSentinel(); } 42 MachineInstr *ensureHead(MachineInstr*) const { return createSentinel(); } 43 static void noteHead(MachineInstr*, MachineInstr*) {} 44 45 void addNodeToList(MachineInstr* N); 46 void removeNodeFromList(MachineInstr* N); 47 void transferNodesFromList(ilist_traits &SrcTraits, 48 ilist_iterator<MachineInstr> first, 49 ilist_iterator<MachineInstr> last); 50 void deleteNode(MachineInstr *N); 51private: 52 void createNode(const MachineInstr &); 53}; 54 55class MachineBasicBlock : public ilist_node<MachineBasicBlock> { 56 typedef ilist<MachineInstr> Instructions; 57 Instructions Insts; 58 const BasicBlock *BB; 59 int Number; 60 MachineFunction *xParent; 61 62 /// Predecessors/Successors - Keep track of the predecessor / successor 63 /// basicblocks. 64 std::vector<MachineBasicBlock *> Predecessors; 65 std::vector<MachineBasicBlock *> Successors; 66 67 /// LiveIns - Keep track of the physical registers that are livein of 68 /// the basicblock. 69 std::vector<unsigned> LiveIns; 70 71 /// Alignment - Alignment of the basic block. Zero if the basic block does 72 /// not need to be aligned. 73 unsigned Alignment; 74 75 /// IsLandingPad - Indicate that this basic block is entered via an 76 /// exception handler. 77 bool IsLandingPad; 78 79 /// AddressTaken - Indicate that this basic block is potentially the 80 /// target of an indirect branch. 81 bool AddressTaken; 82 83 // Intrusive list support 84 MachineBasicBlock() {} 85 86 explicit MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb); 87 88 ~MachineBasicBlock(); 89 90 // MachineBasicBlocks are allocated and owned by MachineFunction. 91 friend class MachineFunction; 92 93public: 94 /// getBasicBlock - Return the LLVM basic block that this instance 95 /// corresponded to originally. Note that this may be NULL if this instance 96 /// does not correspond directly to an LLVM basic block. 97 /// 98 const BasicBlock *getBasicBlock() const { return BB; } 99 100 /// getName - Return the name of the corresponding LLVM basic block, or 101 /// "(null)". 102 StringRef getName() const; 103 104 /// hasAddressTaken - Test whether this block is potentially the target 105 /// of an indirect branch. 106 bool hasAddressTaken() const { return AddressTaken; } 107 108 /// setHasAddressTaken - Set this block to reflect that it potentially 109 /// is the target of an indirect branch. 110 void setHasAddressTaken() { AddressTaken = true; } 111 112 /// getParent - Return the MachineFunction containing this basic block. 113 /// 114 const MachineFunction *getParent() const { return xParent; } 115 MachineFunction *getParent() { return xParent; } 116 117 typedef Instructions::iterator iterator; 118 typedef Instructions::const_iterator const_iterator; 119 typedef std::reverse_iterator<const_iterator> const_reverse_iterator; 120 typedef std::reverse_iterator<iterator> reverse_iterator; 121 122 unsigned size() const { return (unsigned)Insts.size(); } 123 bool empty() const { return Insts.empty(); } 124 125 MachineInstr& front() { return Insts.front(); } 126 MachineInstr& back() { return Insts.back(); } 127 const MachineInstr& front() const { return Insts.front(); } 128 const MachineInstr& back() const { return Insts.back(); } 129 130 iterator begin() { return Insts.begin(); } 131 const_iterator begin() const { return Insts.begin(); } 132 iterator end() { return Insts.end(); } 133 const_iterator end() const { return Insts.end(); } 134 reverse_iterator rbegin() { return Insts.rbegin(); } 135 const_reverse_iterator rbegin() const { return Insts.rbegin(); } 136 reverse_iterator rend () { return Insts.rend(); } 137 const_reverse_iterator rend () const { return Insts.rend(); } 138 139 // Machine-CFG iterators 140 typedef std::vector<MachineBasicBlock *>::iterator pred_iterator; 141 typedef std::vector<MachineBasicBlock *>::const_iterator const_pred_iterator; 142 typedef std::vector<MachineBasicBlock *>::iterator succ_iterator; 143 typedef std::vector<MachineBasicBlock *>::const_iterator const_succ_iterator; 144 typedef std::vector<MachineBasicBlock *>::reverse_iterator 145 pred_reverse_iterator; 146 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator 147 const_pred_reverse_iterator; 148 typedef std::vector<MachineBasicBlock *>::reverse_iterator 149 succ_reverse_iterator; 150 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator 151 const_succ_reverse_iterator; 152 153 pred_iterator pred_begin() { return Predecessors.begin(); } 154 const_pred_iterator pred_begin() const { return Predecessors.begin(); } 155 pred_iterator pred_end() { return Predecessors.end(); } 156 const_pred_iterator pred_end() const { return Predecessors.end(); } 157 pred_reverse_iterator pred_rbegin() 158 { return Predecessors.rbegin();} 159 const_pred_reverse_iterator pred_rbegin() const 160 { return Predecessors.rbegin();} 161 pred_reverse_iterator pred_rend() 162 { return Predecessors.rend(); } 163 const_pred_reverse_iterator pred_rend() const 164 { return Predecessors.rend(); } 165 unsigned pred_size() const { 166 return (unsigned)Predecessors.size(); 167 } 168 bool pred_empty() const { return Predecessors.empty(); } 169 succ_iterator succ_begin() { return Successors.begin(); } 170 const_succ_iterator succ_begin() const { return Successors.begin(); } 171 succ_iterator succ_end() { return Successors.end(); } 172 const_succ_iterator succ_end() const { return Successors.end(); } 173 succ_reverse_iterator succ_rbegin() 174 { return Successors.rbegin(); } 175 const_succ_reverse_iterator succ_rbegin() const 176 { return Successors.rbegin(); } 177 succ_reverse_iterator succ_rend() 178 { return Successors.rend(); } 179 const_succ_reverse_iterator succ_rend() const 180 { return Successors.rend(); } 181 unsigned succ_size() const { 182 return (unsigned)Successors.size(); 183 } 184 bool succ_empty() const { return Successors.empty(); } 185 186 // LiveIn management methods. 187 188 /// addLiveIn - Add the specified register as a live in. Note that it 189 /// is an error to add the same register to the same set more than once. 190 void addLiveIn(unsigned Reg) { LiveIns.push_back(Reg); } 191 192 /// removeLiveIn - Remove the specified register from the live in set. 193 /// 194 void removeLiveIn(unsigned Reg); 195 196 /// isLiveIn - Return true if the specified register is in the live in set. 197 /// 198 bool isLiveIn(unsigned Reg) const; 199 200 // Iteration support for live in sets. These sets are kept in sorted 201 // order by their register number. 202 typedef std::vector<unsigned>::iterator livein_iterator; 203 typedef std::vector<unsigned>::const_iterator const_livein_iterator; 204 livein_iterator livein_begin() { return LiveIns.begin(); } 205 const_livein_iterator livein_begin() const { return LiveIns.begin(); } 206 livein_iterator livein_end() { return LiveIns.end(); } 207 const_livein_iterator livein_end() const { return LiveIns.end(); } 208 bool livein_empty() const { return LiveIns.empty(); } 209 210 /// getAlignment - Return alignment of the basic block. 211 /// 212 unsigned getAlignment() const { return Alignment; } 213 214 /// setAlignment - Set alignment of the basic block. 215 /// 216 void setAlignment(unsigned Align) { Alignment = Align; } 217 218 /// isLandingPad - Returns true if the block is a landing pad. That is 219 /// this basic block is entered via an exception handler. 220 bool isLandingPad() const { return IsLandingPad; } 221 222 /// setIsLandingPad - Indicates the block is a landing pad. That is 223 /// this basic block is entered via an exception handler. 224 void setIsLandingPad() { IsLandingPad = true; } 225 226 // Code Layout methods. 227 228 /// moveBefore/moveAfter - move 'this' block before or after the specified 229 /// block. This only moves the block, it does not modify the CFG or adjust 230 /// potential fall-throughs at the end of the block. 231 void moveBefore(MachineBasicBlock *NewAfter); 232 void moveAfter(MachineBasicBlock *NewBefore); 233 234 /// updateTerminator - Update the terminator instructions in block to account 235 /// for changes to the layout. If the block previously used a fallthrough, 236 /// it may now need a branch, and if it previously used branching it may now 237 /// be able to use a fallthrough. 238 void updateTerminator(); 239 240 // Machine-CFG mutators 241 242 /// addSuccessor - Add succ as a successor of this MachineBasicBlock. 243 /// The Predecessors list of succ is automatically updated. 244 /// 245 void addSuccessor(MachineBasicBlock *succ); 246 247 /// removeSuccessor - Remove successor from the successors list of this 248 /// MachineBasicBlock. The Predecessors list of succ is automatically updated. 249 /// 250 void removeSuccessor(MachineBasicBlock *succ); 251 252 /// removeSuccessor - Remove specified successor from the successors list of 253 /// this MachineBasicBlock. The Predecessors list of succ is automatically 254 /// updated. Return the iterator to the element after the one removed. 255 /// 256 succ_iterator removeSuccessor(succ_iterator I); 257 258 /// transferSuccessors - Transfers all the successors from MBB to this 259 /// machine basic block (i.e., copies all the successors fromMBB and 260 /// remove all the successors from fromMBB). 261 void transferSuccessors(MachineBasicBlock *fromMBB); 262 263 /// isSuccessor - Return true if the specified MBB is a successor of this 264 /// block. 265 bool isSuccessor(const MachineBasicBlock *MBB) const; 266 267 /// isLayoutSuccessor - Return true if the specified MBB will be emitted 268 /// immediately after this block, such that if this block exits by 269 /// falling through, control will transfer to the specified MBB. Note 270 /// that MBB need not be a successor at all, for example if this block 271 /// ends with an unconditional branch to some other block. 272 bool isLayoutSuccessor(const MachineBasicBlock *MBB) const; 273 274 /// canFallThrough - Return true if the block can implicitly transfer 275 /// control to the block after it by falling off the end of it. This should 276 /// return false if it can reach the block after it, but it uses an explicit 277 /// branch to do so (e.g., a table jump). True is a conservative answer. 278 bool canFallThrough(); 279 280 /// getFirstTerminator - returns an iterator to the first terminator 281 /// instruction of this basic block. If a terminator does not exist, 282 /// it returns end() 283 iterator getFirstTerminator(); 284 285 /// isOnlyReachableViaFallthough - Return true if this basic block has 286 /// exactly one predecessor and the control transfer mechanism between 287 /// the predecessor and this block is a fall-through. 288 bool isOnlyReachableByFallthrough() const; 289 290 void pop_front() { Insts.pop_front(); } 291 void pop_back() { Insts.pop_back(); } 292 void push_back(MachineInstr *MI) { Insts.push_back(MI); } 293 template<typename IT> 294 void insert(iterator I, IT S, IT E) { Insts.insert(I, S, E); } 295 iterator insert(iterator I, MachineInstr *M) { return Insts.insert(I, M); } 296 297 // erase - Remove the specified element or range from the instruction list. 298 // These functions delete any instructions removed. 299 // 300 iterator erase(iterator I) { return Insts.erase(I); } 301 iterator erase(iterator I, iterator E) { return Insts.erase(I, E); } 302 MachineInstr *remove(MachineInstr *I) { return Insts.remove(I); } 303 void clear() { Insts.clear(); } 304 305 /// splice - Take an instruction from MBB 'Other' at the position From, 306 /// and insert it into this MBB right before 'where'. 307 void splice(iterator where, MachineBasicBlock *Other, iterator From) { 308 Insts.splice(where, Other->Insts, From); 309 } 310 311 /// splice - Take a block of instructions from MBB 'Other' in the range [From, 312 /// To), and insert them into this MBB right before 'where'. 313 void splice(iterator where, MachineBasicBlock *Other, iterator From, 314 iterator To) { 315 Insts.splice(where, Other->Insts, From, To); 316 } 317 318 /// removeFromParent - This method unlinks 'this' from the containing 319 /// function, and returns it, but does not delete it. 320 MachineBasicBlock *removeFromParent(); 321 322 /// eraseFromParent - This method unlinks 'this' from the containing 323 /// function and deletes it. 324 void eraseFromParent(); 325 326 /// ReplaceUsesOfBlockWith - Given a machine basic block that branched to 327 /// 'Old', change the code and CFG so that it branches to 'New' instead. 328 void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New); 329 330 /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in 331 /// the CFG to be inserted. If we have proven that MBB can only branch to 332 /// DestA and DestB, remove any other MBB successors from the CFG. DestA and 333 /// DestB can be null. Besides DestA and DestB, retain other edges leading 334 /// to LandingPads (currently there can be only one; we don't check or require 335 /// that here). Note it is possible that DestA and/or DestB are LandingPads. 336 bool CorrectExtraCFGEdges(MachineBasicBlock *DestA, 337 MachineBasicBlock *DestB, 338 bool isCond); 339 340 // Debugging methods. 341 void dump() const; 342 void print(raw_ostream &OS) const; 343 344 /// getNumber - MachineBasicBlocks are uniquely numbered at the function 345 /// level, unless they're not in a MachineFunction yet, in which case this 346 /// will return -1. 347 /// 348 int getNumber() const { return Number; } 349 void setNumber(int N) { Number = N; } 350 351private: // Methods used to maintain doubly linked list of blocks... 352 friend struct ilist_traits<MachineBasicBlock>; 353 354 // Machine-CFG mutators 355 356 /// addPredecessor - Remove pred as a predecessor of this MachineBasicBlock. 357 /// Don't do this unless you know what you're doing, because it doesn't 358 /// update pred's successors list. Use pred->addSuccessor instead. 359 /// 360 void addPredecessor(MachineBasicBlock *pred); 361 362 /// removePredecessor - Remove pred as a predecessor of this 363 /// MachineBasicBlock. Don't do this unless you know what you're 364 /// doing, because it doesn't update pred's successors list. Use 365 /// pred->removeSuccessor instead. 366 /// 367 void removePredecessor(MachineBasicBlock *pred); 368}; 369 370raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB); 371 372void WriteAsOperand(raw_ostream &, const MachineBasicBlock*, bool t); 373 374//===--------------------------------------------------------------------===// 375// GraphTraits specializations for machine basic block graphs (machine-CFGs) 376//===--------------------------------------------------------------------===// 377 378// Provide specializations of GraphTraits to be able to treat a 379// MachineFunction as a graph of MachineBasicBlocks... 380// 381 382template <> struct GraphTraits<MachineBasicBlock *> { 383 typedef MachineBasicBlock NodeType; 384 typedef MachineBasicBlock::succ_iterator ChildIteratorType; 385 386 static NodeType *getEntryNode(MachineBasicBlock *BB) { return BB; } 387 static inline ChildIteratorType child_begin(NodeType *N) { 388 return N->succ_begin(); 389 } 390 static inline ChildIteratorType child_end(NodeType *N) { 391 return N->succ_end(); 392 } 393}; 394 395template <> struct GraphTraits<const MachineBasicBlock *> { 396 typedef const MachineBasicBlock NodeType; 397 typedef MachineBasicBlock::const_succ_iterator ChildIteratorType; 398 399 static NodeType *getEntryNode(const MachineBasicBlock *BB) { return BB; } 400 static inline ChildIteratorType child_begin(NodeType *N) { 401 return N->succ_begin(); 402 } 403 static inline ChildIteratorType child_end(NodeType *N) { 404 return N->succ_end(); 405 } 406}; 407 408// Provide specializations of GraphTraits to be able to treat a 409// MachineFunction as a graph of MachineBasicBlocks... and to walk it 410// in inverse order. Inverse order for a function is considered 411// to be when traversing the predecessor edges of a MBB 412// instead of the successor edges. 413// 414template <> struct GraphTraits<Inverse<MachineBasicBlock*> > { 415 typedef MachineBasicBlock NodeType; 416 typedef MachineBasicBlock::pred_iterator ChildIteratorType; 417 static NodeType *getEntryNode(Inverse<MachineBasicBlock *> G) { 418 return G.Graph; 419 } 420 static inline ChildIteratorType child_begin(NodeType *N) { 421 return N->pred_begin(); 422 } 423 static inline ChildIteratorType child_end(NodeType *N) { 424 return N->pred_end(); 425 } 426}; 427 428template <> struct GraphTraits<Inverse<const MachineBasicBlock*> > { 429 typedef const MachineBasicBlock NodeType; 430 typedef MachineBasicBlock::const_pred_iterator ChildIteratorType; 431 static NodeType *getEntryNode(Inverse<const MachineBasicBlock*> G) { 432 return G.Graph; 433 } 434 static inline ChildIteratorType child_begin(NodeType *N) { 435 return N->pred_begin(); 436 } 437 static inline ChildIteratorType child_end(NodeType *N) { 438 return N->pred_end(); 439 } 440}; 441 442} // End llvm namespace 443 444#endif 445