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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 "llvm/Support/DataTypes.h"
20 #include <functional>
21 
22 namespace llvm {
23 
24 class Pass;
25 class BasicBlock;
26 class MachineFunction;
27 class MCSymbol;
28 class SlotIndexes;
29 class StringRef;
30 class raw_ostream;
31 class MachineBranchProbabilityInfo;
32 
33 template <>
34 struct ilist_traits<MachineInstr> : public ilist_default_traits<MachineInstr> {
35 private:
36   mutable ilist_half_node<MachineInstr> Sentinel;
37 
38   // this is only set by the MachineBasicBlock owning the LiveList
39   friend class MachineBasicBlock;
40   MachineBasicBlock* Parent;
41 
42 public:
43   MachineInstr *createSentinel() const {
44     return static_cast<MachineInstr*>(&Sentinel);
45   }
46   void destroySentinel(MachineInstr *) const {}
47 
48   MachineInstr *provideInitialHead() const { return createSentinel(); }
49   MachineInstr *ensureHead(MachineInstr*) const { return createSentinel(); }
50   static void noteHead(MachineInstr*, MachineInstr*) {}
51 
52   void addNodeToList(MachineInstr* N);
53   void removeNodeFromList(MachineInstr* N);
54   void transferNodesFromList(ilist_traits &SrcTraits,
55                              ilist_iterator<MachineInstr> first,
56                              ilist_iterator<MachineInstr> last);
57   void deleteNode(MachineInstr *N);
58 private:
59   void createNode(const MachineInstr &);
60 };
61 
62 class MachineBasicBlock : public ilist_node<MachineBasicBlock> {
63   typedef ilist<MachineInstr> Instructions;
64   Instructions Insts;
65   const BasicBlock *BB;
66   int Number;
67   MachineFunction *xParent;
68 
69   /// Predecessors/Successors - Keep track of the predecessor / successor
70   /// basicblocks.
71   std::vector<MachineBasicBlock *> Predecessors;
72   std::vector<MachineBasicBlock *> Successors;
73 
74 
75   /// Weights - Keep track of the weights to the successors. This vector
76   /// has the same order as Successors, or it is empty if we don't use it
77   /// (disable optimization).
78   std::vector<uint32_t> Weights;
79   typedef std::vector<uint32_t>::iterator weight_iterator;
80   typedef std::vector<uint32_t>::const_iterator const_weight_iterator;
81 
82   /// LiveIns - Keep track of the physical registers that are livein of
83   /// the basicblock.
84   std::vector<unsigned> LiveIns;
85 
86   /// Alignment - Alignment of the basic block. Zero if the basic block does
87   /// not need to be aligned.
88   /// The alignment is specified as log2(bytes).
89   unsigned Alignment;
90 
91   /// IsLandingPad - Indicate that this basic block is entered via an
92   /// exception handler.
93   bool IsLandingPad;
94 
95   /// AddressTaken - Indicate that this basic block is potentially the
96   /// target of an indirect branch.
97   bool AddressTaken;
98 
99   // Intrusive list support
100   MachineBasicBlock() {}
101 
102   explicit MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb);
103 
104   ~MachineBasicBlock();
105 
106   // MachineBasicBlocks are allocated and owned by MachineFunction.
107   friend class MachineFunction;
108 
109 public:
110   /// getBasicBlock - Return the LLVM basic block that this instance
111   /// corresponded to originally. Note that this may be NULL if this instance
112   /// does not correspond directly to an LLVM basic block.
113   ///
114   const BasicBlock *getBasicBlock() const { return BB; }
115 
116   /// getName - Return the name of the corresponding LLVM basic block, or
117   /// "(null)".
118   StringRef getName() const;
119 
120   /// getFullName - Return a formatted string to identify this block and its
121   /// parent function.
122   std::string getFullName() const;
123 
124   /// hasAddressTaken - Test whether this block is potentially the target
125   /// of an indirect branch.
126   bool hasAddressTaken() const { return AddressTaken; }
127 
128   /// setHasAddressTaken - Set this block to reflect that it potentially
129   /// is the target of an indirect branch.
130   void setHasAddressTaken() { AddressTaken = true; }
131 
132   /// getParent - Return the MachineFunction containing this basic block.
133   ///
134   const MachineFunction *getParent() const { return xParent; }
135   MachineFunction *getParent() { return xParent; }
136 
137 
138   /// bundle_iterator - MachineBasicBlock iterator that automatically skips over
139   /// MIs that are inside bundles (i.e. walk top level MIs only).
140   template<typename Ty, typename IterTy>
141   class bundle_iterator
142     : public std::iterator<std::bidirectional_iterator_tag, Ty, ptrdiff_t> {
143     IterTy MII;
144 
145   public:
146     bundle_iterator(IterTy mii) : MII(mii) {
147       assert(!MII->isInsideBundle() &&
148              "It's not legal to initialize bundle_iterator with a bundled MI");
149     }
150 
151     bundle_iterator(Ty &mi) : MII(mi) {
152       assert(!mi.isInsideBundle() &&
153              "It's not legal to initialize bundle_iterator with a bundled MI");
154     }
155     bundle_iterator(Ty *mi) : MII(mi) {
156       assert((!mi || !mi->isInsideBundle()) &&
157              "It's not legal to initialize bundle_iterator with a bundled MI");
158     }
159     bundle_iterator(const bundle_iterator &I) : MII(I.MII) {}
160     bundle_iterator() : MII(0) {}
161 
162     Ty &operator*() const { return *MII; }
163     Ty *operator->() const { return &operator*(); }
164 
165     operator Ty*() const { return MII; }
166 
167     bool operator==(const bundle_iterator &x) const {
168       return MII == x.MII;
169     }
170     bool operator!=(const bundle_iterator &x) const {
171       return !operator==(x);
172     }
173 
174     // Increment and decrement operators...
175     bundle_iterator &operator--() {      // predecrement - Back up
176       do {
177         --MII;
178       } while (MII->isInsideBundle());
179       return *this;
180     }
181     bundle_iterator &operator++() {      // preincrement - Advance
182       do {
183         ++MII;
184       } while (MII->isInsideBundle());
185       return *this;
186     }
187     bundle_iterator operator--(int) {    // postdecrement operators...
188       bundle_iterator tmp = *this;
189       do {
190         --MII;
191       } while (MII->isInsideBundle());
192       return tmp;
193     }
194     bundle_iterator operator++(int) {    // postincrement operators...
195       bundle_iterator tmp = *this;
196       do {
197         ++MII;
198       } while (MII->isInsideBundle());
199       return tmp;
200     }
201 
202     IterTy getInstrIterator() const {
203       return MII;
204     }
205   };
206 
207   typedef Instructions::iterator                                 instr_iterator;
208   typedef Instructions::const_iterator                     const_instr_iterator;
209   typedef std::reverse_iterator<instr_iterator>          reverse_instr_iterator;
210   typedef
211   std::reverse_iterator<const_instr_iterator>      const_reverse_instr_iterator;
212 
213   typedef
214   bundle_iterator<MachineInstr,instr_iterator>                         iterator;
215   typedef
216   bundle_iterator<const MachineInstr,const_instr_iterator>       const_iterator;
217   typedef std::reverse_iterator<const_iterator>          const_reverse_iterator;
218   typedef std::reverse_iterator<iterator>                      reverse_iterator;
219 
220 
221   unsigned size() const { return (unsigned)Insts.size(); }
222   bool empty() const { return Insts.empty(); }
223 
224   MachineInstr& front() { return Insts.front(); }
225   MachineInstr& back()  { return Insts.back(); }
226   const MachineInstr& front() const { return Insts.front(); }
227   const MachineInstr& back()  const { return Insts.back(); }
228 
229   instr_iterator                instr_begin()       { return Insts.begin();  }
230   const_instr_iterator          instr_begin() const { return Insts.begin();  }
231   instr_iterator                  instr_end()       { return Insts.end();    }
232   const_instr_iterator            instr_end() const { return Insts.end();    }
233   reverse_instr_iterator       instr_rbegin()       { return Insts.rbegin(); }
234   const_reverse_instr_iterator instr_rbegin() const { return Insts.rbegin(); }
235   reverse_instr_iterator       instr_rend  ()       { return Insts.rend();   }
236   const_reverse_instr_iterator instr_rend  () const { return Insts.rend();   }
237 
238   iterator                begin()       { return Insts.begin();  }
239   const_iterator          begin() const { return Insts.begin();  }
240   iterator                  end()       {
241     instr_iterator II = instr_end();
242     if (II != instr_begin()) {
243       while (II->isInsideBundle())
244         --II;
245     }
246     return II;
247   }
248   const_iterator            end() const {
249     const_instr_iterator II = instr_end();
250     if (II != instr_begin()) {
251       while (II->isInsideBundle())
252         --II;
253     }
254     return II;
255   }
256   reverse_iterator       rbegin()       {
257     reverse_instr_iterator II = instr_rbegin();
258     if (II != instr_rend()) {
259       while (II->isInsideBundle())
260         ++II;
261     }
262     return II;
263   }
264   const_reverse_iterator rbegin() const {
265     const_reverse_instr_iterator II = instr_rbegin();
266     if (II != instr_rend()) {
267       while (II->isInsideBundle())
268         ++II;
269     }
270     return II;
271   }
272   reverse_iterator       rend  ()       { return Insts.rend();   }
273   const_reverse_iterator rend  () const { return Insts.rend();   }
274 
275 
276   // Machine-CFG iterators
277   typedef std::vector<MachineBasicBlock *>::iterator       pred_iterator;
278   typedef std::vector<MachineBasicBlock *>::const_iterator const_pred_iterator;
279   typedef std::vector<MachineBasicBlock *>::iterator       succ_iterator;
280   typedef std::vector<MachineBasicBlock *>::const_iterator const_succ_iterator;
281   typedef std::vector<MachineBasicBlock *>::reverse_iterator
282                                                          pred_reverse_iterator;
283   typedef std::vector<MachineBasicBlock *>::const_reverse_iterator
284                                                    const_pred_reverse_iterator;
285   typedef std::vector<MachineBasicBlock *>::reverse_iterator
286                                                          succ_reverse_iterator;
287   typedef std::vector<MachineBasicBlock *>::const_reverse_iterator
288                                                    const_succ_reverse_iterator;
289 
290   pred_iterator        pred_begin()       { return Predecessors.begin(); }
291   const_pred_iterator  pred_begin() const { return Predecessors.begin(); }
292   pred_iterator        pred_end()         { return Predecessors.end();   }
293   const_pred_iterator  pred_end()   const { return Predecessors.end();   }
294   pred_reverse_iterator        pred_rbegin()
295                                           { return Predecessors.rbegin();}
296   const_pred_reverse_iterator  pred_rbegin() const
297                                           { return Predecessors.rbegin();}
298   pred_reverse_iterator        pred_rend()
299                                           { return Predecessors.rend();  }
300   const_pred_reverse_iterator  pred_rend()   const
301                                           { return Predecessors.rend();  }
302   unsigned             pred_size()  const {
303     return (unsigned)Predecessors.size();
304   }
305   bool                 pred_empty() const { return Predecessors.empty(); }
306   succ_iterator        succ_begin()       { return Successors.begin();   }
307   const_succ_iterator  succ_begin() const { return Successors.begin();   }
308   succ_iterator        succ_end()         { return Successors.end();     }
309   const_succ_iterator  succ_end()   const { return Successors.end();     }
310   succ_reverse_iterator        succ_rbegin()
311                                           { return Successors.rbegin();  }
312   const_succ_reverse_iterator  succ_rbegin() const
313                                           { return Successors.rbegin();  }
314   succ_reverse_iterator        succ_rend()
315                                           { return Successors.rend();    }
316   const_succ_reverse_iterator  succ_rend()   const
317                                           { return Successors.rend();    }
318   unsigned             succ_size()  const {
319     return (unsigned)Successors.size();
320   }
321   bool                 succ_empty() const { return Successors.empty();   }
322 
323   // LiveIn management methods.
324 
325   /// addLiveIn - Add the specified register as a live in.  Note that it
326   /// is an error to add the same register to the same set more than once.
327   void addLiveIn(unsigned Reg)  { LiveIns.push_back(Reg); }
328 
329   /// removeLiveIn - Remove the specified register from the live in set.
330   ///
331   void removeLiveIn(unsigned Reg);
332 
333   /// isLiveIn - Return true if the specified register is in the live in set.
334   ///
335   bool isLiveIn(unsigned Reg) const;
336 
337   // Iteration support for live in sets.  These sets are kept in sorted
338   // order by their register number.
339   typedef std::vector<unsigned>::const_iterator livein_iterator;
340   livein_iterator livein_begin() const { return LiveIns.begin(); }
341   livein_iterator livein_end()   const { return LiveIns.end(); }
342   bool            livein_empty() const { return LiveIns.empty(); }
343 
344   /// getAlignment - Return alignment of the basic block.
345   /// The alignment is specified as log2(bytes).
346   ///
347   unsigned getAlignment() const { return Alignment; }
348 
349   /// setAlignment - Set alignment of the basic block.
350   /// The alignment is specified as log2(bytes).
351   ///
352   void setAlignment(unsigned Align) { Alignment = Align; }
353 
354   /// isLandingPad - Returns true if the block is a landing pad. That is
355   /// this basic block is entered via an exception handler.
356   bool isLandingPad() const { return IsLandingPad; }
357 
358   /// setIsLandingPad - Indicates the block is a landing pad.  That is
359   /// this basic block is entered via an exception handler.
360   void setIsLandingPad(bool V = true) { IsLandingPad = V; }
361 
362   /// getLandingPadSuccessor - If this block has a successor that is a landing
363   /// pad, return it. Otherwise return NULL.
364   const MachineBasicBlock *getLandingPadSuccessor() const;
365 
366   // Code Layout methods.
367 
368   /// moveBefore/moveAfter - move 'this' block before or after the specified
369   /// block.  This only moves the block, it does not modify the CFG or adjust
370   /// potential fall-throughs at the end of the block.
371   void moveBefore(MachineBasicBlock *NewAfter);
372   void moveAfter(MachineBasicBlock *NewBefore);
373 
374   /// updateTerminator - Update the terminator instructions in block to account
375   /// for changes to the layout. If the block previously used a fallthrough,
376   /// it may now need a branch, and if it previously used branching it may now
377   /// be able to use a fallthrough.
378   void updateTerminator();
379 
380   // Machine-CFG mutators
381 
382   /// addSuccessor - Add succ as a successor of this MachineBasicBlock.
383   /// The Predecessors list of succ is automatically updated. WEIGHT
384   /// parameter is stored in Weights list and it may be used by
385   /// MachineBranchProbabilityInfo analysis to calculate branch probability.
386   ///
387   void addSuccessor(MachineBasicBlock *succ, uint32_t weight = 0);
388 
389   /// removeSuccessor - Remove successor from the successors list of this
390   /// MachineBasicBlock. The Predecessors list of succ is automatically updated.
391   ///
392   void removeSuccessor(MachineBasicBlock *succ);
393 
394   /// removeSuccessor - Remove specified successor from the successors list of
395   /// this MachineBasicBlock. The Predecessors list of succ is automatically
396   /// updated.  Return the iterator to the element after the one removed.
397   ///
398   succ_iterator removeSuccessor(succ_iterator I);
399 
400   /// replaceSuccessor - Replace successor OLD with NEW and update weight info.
401   ///
402   void replaceSuccessor(MachineBasicBlock *Old, MachineBasicBlock *New);
403 
404 
405   /// transferSuccessors - Transfers all the successors from MBB to this
406   /// machine basic block (i.e., copies all the successors fromMBB and
407   /// remove all the successors from fromMBB).
408   void transferSuccessors(MachineBasicBlock *fromMBB);
409 
410   /// transferSuccessorsAndUpdatePHIs - Transfers all the successors, as
411   /// in transferSuccessors, and update PHI operands in the successor blocks
412   /// which refer to fromMBB to refer to this.
413   void transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB);
414 
415   /// isSuccessor - Return true if the specified MBB is a successor of this
416   /// block.
417   bool isSuccessor(const MachineBasicBlock *MBB) const;
418 
419   /// isLayoutSuccessor - Return true if the specified MBB will be emitted
420   /// immediately after this block, such that if this block exits by
421   /// falling through, control will transfer to the specified MBB. Note
422   /// that MBB need not be a successor at all, for example if this block
423   /// ends with an unconditional branch to some other block.
424   bool isLayoutSuccessor(const MachineBasicBlock *MBB) const;
425 
426   /// canFallThrough - Return true if the block can implicitly transfer
427   /// control to the block after it by falling off the end of it.  This should
428   /// return false if it can reach the block after it, but it uses an explicit
429   /// branch to do so (e.g., a table jump).  True is a conservative answer.
430   bool canFallThrough();
431 
432   /// Returns a pointer to the first instructon in this block that is not a
433   /// PHINode instruction. When adding instruction to the beginning of the
434   /// basic block, they should be added before the returned value, not before
435   /// the first instruction, which might be PHI.
436   /// Returns end() is there's no non-PHI instruction.
437   iterator getFirstNonPHI();
438 
439   /// SkipPHIsAndLabels - Return the first instruction in MBB after I that is
440   /// not a PHI or a label. This is the correct point to insert copies at the
441   /// beginning of a basic block.
442   iterator SkipPHIsAndLabels(iterator I);
443 
444   /// getFirstTerminator - returns an iterator to the first terminator
445   /// instruction of this basic block. If a terminator does not exist,
446   /// it returns end()
447   iterator getFirstTerminator();
448   const_iterator getFirstTerminator() const;
449 
450   /// getFirstInstrTerminator - Same getFirstTerminator but it ignores bundles
451   /// and return an instr_iterator instead.
452   instr_iterator getFirstInstrTerminator();
453 
454   /// getLastNonDebugInstr - returns an iterator to the last non-debug
455   /// instruction in the basic block, or end()
456   iterator getLastNonDebugInstr();
457   const_iterator getLastNonDebugInstr() const;
458 
459   /// SplitCriticalEdge - Split the critical edge from this block to the
460   /// given successor block, and return the newly created block, or null
461   /// if splitting is not possible.
462   ///
463   /// This function updates LiveVariables, MachineDominatorTree, and
464   /// MachineLoopInfo, as applicable.
465   MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P);
466 
467   void pop_front() { Insts.pop_front(); }
468   void pop_back() { Insts.pop_back(); }
469   void push_back(MachineInstr *MI) { Insts.push_back(MI); }
470 
471   template<typename IT>
472   void insert(instr_iterator I, IT S, IT E) {
473     Insts.insert(I, S, E);
474   }
475   instr_iterator insert(instr_iterator I, MachineInstr *M) {
476     return Insts.insert(I, M);
477   }
478   instr_iterator insertAfter(instr_iterator I, MachineInstr *M) {
479     return Insts.insertAfter(I, M);
480   }
481 
482   template<typename IT>
483   void insert(iterator I, IT S, IT E) {
484     Insts.insert(I.getInstrIterator(), S, E);
485   }
486   iterator insert(iterator I, MachineInstr *M) {
487     return Insts.insert(I.getInstrIterator(), M);
488   }
489   iterator insertAfter(iterator I, MachineInstr *M) {
490     return Insts.insertAfter(I.getInstrIterator(), M);
491   }
492 
493   /// erase - Remove the specified element or range from the instruction list.
494   /// These functions delete any instructions removed.
495   ///
496   instr_iterator erase(instr_iterator I) {
497     return Insts.erase(I);
498   }
499   instr_iterator erase(instr_iterator I, instr_iterator E) {
500     return Insts.erase(I, E);
501   }
502   instr_iterator erase_instr(MachineInstr *I) {
503     instr_iterator MII(I);
504     return erase(MII);
505   }
506 
507   iterator erase(iterator I);
508   iterator erase(iterator I, iterator E) {
509     return Insts.erase(I.getInstrIterator(), E.getInstrIterator());
510   }
511   iterator erase(MachineInstr *I) {
512     iterator MII(I);
513     return erase(MII);
514   }
515 
516   /// remove - Remove the instruction from the instruction list. This function
517   /// does not delete the instruction. WARNING: Note, if the specified
518   /// instruction is a bundle this function will remove all the bundled
519   /// instructions as well. It is up to the caller to keep a list of the
520   /// bundled instructions and re-insert them if desired. This function is
521   /// *not recommended* for manipulating instructions with bundles. Use
522   /// splice instead.
523   MachineInstr *remove(MachineInstr *I);
524   void clear() {
525     Insts.clear();
526   }
527 
528   /// splice - Take an instruction from MBB 'Other' at the position From,
529   /// and insert it into this MBB right before 'where'.
530   void splice(instr_iterator where, MachineBasicBlock *Other,
531               instr_iterator From) {
532     Insts.splice(where, Other->Insts, From);
533   }
534   void splice(iterator where, MachineBasicBlock *Other, iterator From);
535 
536   /// splice - Take a block of instructions from MBB 'Other' in the range [From,
537   /// To), and insert them into this MBB right before 'where'.
538   void splice(instr_iterator where, MachineBasicBlock *Other, instr_iterator From,
539               instr_iterator To) {
540     Insts.splice(where, Other->Insts, From, To);
541   }
542   void splice(iterator where, MachineBasicBlock *Other, iterator From,
543               iterator To) {
544     Insts.splice(where.getInstrIterator(), Other->Insts,
545                  From.getInstrIterator(), To.getInstrIterator());
546   }
547 
548   /// removeFromParent - This method unlinks 'this' from the containing
549   /// function, and returns it, but does not delete it.
550   MachineBasicBlock *removeFromParent();
551 
552   /// eraseFromParent - This method unlinks 'this' from the containing
553   /// function and deletes it.
554   void eraseFromParent();
555 
556   /// ReplaceUsesOfBlockWith - Given a machine basic block that branched to
557   /// 'Old', change the code and CFG so that it branches to 'New' instead.
558   void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New);
559 
560   /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in
561   /// the CFG to be inserted.  If we have proven that MBB can only branch to
562   /// DestA and DestB, remove any other MBB successors from the CFG. DestA and
563   /// DestB can be null. Besides DestA and DestB, retain other edges leading
564   /// to LandingPads (currently there can be only one; we don't check or require
565   /// that here). Note it is possible that DestA and/or DestB are LandingPads.
566   bool CorrectExtraCFGEdges(MachineBasicBlock *DestA,
567                             MachineBasicBlock *DestB,
568                             bool isCond);
569 
570   /// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping
571   /// any DBG_VALUE instructions.  Return UnknownLoc if there is none.
572   DebugLoc findDebugLoc(instr_iterator MBBI);
573   DebugLoc findDebugLoc(iterator MBBI) {
574     return findDebugLoc(MBBI.getInstrIterator());
575   }
576 
577   // Debugging methods.
578   void dump() const;
579   void print(raw_ostream &OS, SlotIndexes* = 0) const;
580 
581   /// getNumber - MachineBasicBlocks are uniquely numbered at the function
582   /// level, unless they're not in a MachineFunction yet, in which case this
583   /// will return -1.
584   ///
585   int getNumber() const { return Number; }
586   void setNumber(int N) { Number = N; }
587 
588   /// getSymbol - Return the MCSymbol for this basic block.
589   ///
590   MCSymbol *getSymbol() const;
591 
592 
593 private:
594   /// getWeightIterator - Return weight iterator corresponding to the I
595   /// successor iterator.
596   weight_iterator getWeightIterator(succ_iterator I);
597   const_weight_iterator getWeightIterator(const_succ_iterator I) const;
598 
599   friend class MachineBranchProbabilityInfo;
600 
601   /// getSuccWeight - Return weight of the edge from this block to MBB. This
602   /// method should NOT be called directly, but by using getEdgeWeight method
603   /// from MachineBranchProbabilityInfo class.
604   uint32_t getSuccWeight(const MachineBasicBlock *succ) const;
605 
606 
607   // Methods used to maintain doubly linked list of blocks...
608   friend struct ilist_traits<MachineBasicBlock>;
609 
610   // Machine-CFG mutators
611 
612   /// addPredecessor - Remove pred as a predecessor of this MachineBasicBlock.
613   /// Don't do this unless you know what you're doing, because it doesn't
614   /// update pred's successors list. Use pred->addSuccessor instead.
615   ///
616   void addPredecessor(MachineBasicBlock *pred);
617 
618   /// removePredecessor - Remove pred as a predecessor of this
619   /// MachineBasicBlock. Don't do this unless you know what you're
620   /// doing, because it doesn't update pred's successors list. Use
621   /// pred->removeSuccessor instead.
622   ///
623   void removePredecessor(MachineBasicBlock *pred);
624 };
625 
626 raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB);
627 
628 void WriteAsOperand(raw_ostream &, const MachineBasicBlock*, bool t);
629 
630 // This is useful when building IndexedMaps keyed on basic block pointers.
631 struct MBB2NumberFunctor :
632   public std::unary_function<const MachineBasicBlock*, unsigned> {
633   unsigned operator()(const MachineBasicBlock *MBB) const {
634     return MBB->getNumber();
635   }
636 };
637 
638 //===--------------------------------------------------------------------===//
639 // GraphTraits specializations for machine basic block graphs (machine-CFGs)
640 //===--------------------------------------------------------------------===//
641 
642 // Provide specializations of GraphTraits to be able to treat a
643 // MachineFunction as a graph of MachineBasicBlocks...
644 //
645 
646 template <> struct GraphTraits<MachineBasicBlock *> {
647   typedef MachineBasicBlock NodeType;
648   typedef MachineBasicBlock::succ_iterator ChildIteratorType;
649 
650   static NodeType *getEntryNode(MachineBasicBlock *BB) { return BB; }
651   static inline ChildIteratorType child_begin(NodeType *N) {
652     return N->succ_begin();
653   }
654   static inline ChildIteratorType child_end(NodeType *N) {
655     return N->succ_end();
656   }
657 };
658 
659 template <> struct GraphTraits<const MachineBasicBlock *> {
660   typedef const MachineBasicBlock NodeType;
661   typedef MachineBasicBlock::const_succ_iterator ChildIteratorType;
662 
663   static NodeType *getEntryNode(const MachineBasicBlock *BB) { return BB; }
664   static inline ChildIteratorType child_begin(NodeType *N) {
665     return N->succ_begin();
666   }
667   static inline ChildIteratorType child_end(NodeType *N) {
668     return N->succ_end();
669   }
670 };
671 
672 // Provide specializations of GraphTraits to be able to treat a
673 // MachineFunction as a graph of MachineBasicBlocks... and to walk it
674 // in inverse order.  Inverse order for a function is considered
675 // to be when traversing the predecessor edges of a MBB
676 // instead of the successor edges.
677 //
678 template <> struct GraphTraits<Inverse<MachineBasicBlock*> > {
679   typedef MachineBasicBlock NodeType;
680   typedef MachineBasicBlock::pred_iterator ChildIteratorType;
681   static NodeType *getEntryNode(Inverse<MachineBasicBlock *> G) {
682     return G.Graph;
683   }
684   static inline ChildIteratorType child_begin(NodeType *N) {
685     return N->pred_begin();
686   }
687   static inline ChildIteratorType child_end(NodeType *N) {
688     return N->pred_end();
689   }
690 };
691 
692 template <> struct GraphTraits<Inverse<const MachineBasicBlock*> > {
693   typedef const MachineBasicBlock NodeType;
694   typedef MachineBasicBlock::const_pred_iterator ChildIteratorType;
695   static NodeType *getEntryNode(Inverse<const MachineBasicBlock*> G) {
696     return G.Graph;
697   }
698   static inline ChildIteratorType child_begin(NodeType *N) {
699     return N->pred_begin();
700   }
701   static inline ChildIteratorType child_end(NodeType *N) {
702     return N->pred_end();
703   }
704 };
705 
706 } // End llvm namespace
707 
708 #endif
709