1 //===-- llvm/CodeGen/MachineBasicBlock.h ------------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Collect the sequence of machine instructions for a basic block.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CODEGEN_MACHINEBASICBLOCK_H
15 #define LLVM_CODEGEN_MACHINEBASICBLOCK_H
17 #include "llvm/ADT/GraphTraits.h"
18 #include "llvm/CodeGen/MachineInstr.h"
19 #include "llvm/Support/DataTypes.h"
26 class MachineFunction;
31 class MachineBranchProbabilityInfo;
34 struct ilist_traits<MachineInstr> : public ilist_default_traits<MachineInstr> {
36 mutable ilist_half_node<MachineInstr> Sentinel;
38 // this is only set by the MachineBasicBlock owning the LiveList
39 friend class MachineBasicBlock;
40 MachineBasicBlock* Parent;
43 MachineInstr *createSentinel() const {
44 return static_cast<MachineInstr*>(&Sentinel);
46 void destroySentinel(MachineInstr *) const {}
48 MachineInstr *provideInitialHead() const { return createSentinel(); }
49 MachineInstr *ensureHead(MachineInstr*) const { return createSentinel(); }
50 static void noteHead(MachineInstr*, MachineInstr*) {}
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);
59 void createNode(const MachineInstr &);
62 class MachineBasicBlock : public ilist_node<MachineBasicBlock> {
63 typedef ilist<MachineInstr> Instructions;
67 MachineFunction *xParent;
69 /// Predecessors/Successors - Keep track of the predecessor / successor
71 std::vector<MachineBasicBlock *> Predecessors;
72 std::vector<MachineBasicBlock *> Successors;
74 /// Weights - Keep track of the weights to the successors. This vector
75 /// has the same order as Successors, or it is empty if we don't use it
76 /// (disable optimization).
77 std::vector<uint32_t> Weights;
78 typedef std::vector<uint32_t>::iterator weight_iterator;
79 typedef std::vector<uint32_t>::const_iterator const_weight_iterator;
81 /// LiveIns - Keep track of the physical registers that are livein of
83 std::vector<unsigned> LiveIns;
85 /// Alignment - Alignment of the basic block. Zero if the basic block does
86 /// not need to be aligned.
87 /// The alignment is specified as log2(bytes).
90 /// IsLandingPad - Indicate that this basic block is entered via an
91 /// exception handler.
94 /// AddressTaken - Indicate that this basic block is potentially the
95 /// target of an indirect branch.
98 /// \brief since getSymbol is a relatively heavy-weight operation, the symbol
99 /// is only computed once and is cached.
100 mutable MCSymbol *CachedMCSymbol;
102 // Intrusive list support
103 MachineBasicBlock() {}
105 explicit MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb);
107 ~MachineBasicBlock();
109 // MachineBasicBlocks are allocated and owned by MachineFunction.
110 friend class MachineFunction;
113 /// getBasicBlock - Return the LLVM basic block that this instance
114 /// corresponded to originally. Note that this may be NULL if this instance
115 /// does not correspond directly to an LLVM basic block.
117 const BasicBlock *getBasicBlock() const { return BB; }
119 /// getName - Return the name of the corresponding LLVM basic block, or
121 StringRef getName() const;
123 /// getFullName - Return a formatted string to identify this block and its
125 std::string getFullName() const;
127 /// hasAddressTaken - Test whether this block is potentially the target
128 /// of an indirect branch.
129 bool hasAddressTaken() const { return AddressTaken; }
131 /// setHasAddressTaken - Set this block to reflect that it potentially
132 /// is the target of an indirect branch.
133 void setHasAddressTaken() { AddressTaken = true; }
135 /// getParent - Return the MachineFunction containing this basic block.
137 const MachineFunction *getParent() const { return xParent; }
138 MachineFunction *getParent() { return xParent; }
141 /// bundle_iterator - MachineBasicBlock iterator that automatically skips over
142 /// MIs that are inside bundles (i.e. walk top level MIs only).
143 template<typename Ty, typename IterTy>
144 class bundle_iterator
145 : public std::iterator<std::bidirectional_iterator_tag, Ty, ptrdiff_t> {
149 bundle_iterator(IterTy mii) : MII(mii) {}
151 bundle_iterator(Ty &mi) : MII(mi) {
152 assert(!mi.isBundledWithPred() &&
153 "It's not legal to initialize bundle_iterator with a bundled MI");
155 bundle_iterator(Ty *mi) : MII(mi) {
156 assert((!mi || !mi->isBundledWithPred()) &&
157 "It's not legal to initialize bundle_iterator with a bundled MI");
159 // Template allows conversion from const to nonconst.
160 template<class OtherTy, class OtherIterTy>
161 bundle_iterator(const bundle_iterator<OtherTy, OtherIterTy> &I)
162 : MII(I.getInstrIterator()) {}
163 bundle_iterator() : MII(0) {}
165 Ty &operator*() const { return *MII; }
166 Ty *operator->() const { return &operator*(); }
168 operator Ty*() const { return MII; }
170 bool operator==(const bundle_iterator &x) const {
173 bool operator!=(const bundle_iterator &x) const {
174 return !operator==(x);
177 // Increment and decrement operators...
178 bundle_iterator &operator--() { // predecrement - Back up
180 while (MII->isBundledWithPred());
183 bundle_iterator &operator++() { // preincrement - Advance
184 while (MII->isBundledWithSucc())
189 bundle_iterator operator--(int) { // postdecrement operators...
190 bundle_iterator tmp = *this;
194 bundle_iterator operator++(int) { // postincrement operators...
195 bundle_iterator tmp = *this;
200 IterTy getInstrIterator() const {
205 typedef Instructions::iterator instr_iterator;
206 typedef Instructions::const_iterator const_instr_iterator;
207 typedef std::reverse_iterator<instr_iterator> reverse_instr_iterator;
209 std::reverse_iterator<const_instr_iterator> const_reverse_instr_iterator;
212 bundle_iterator<MachineInstr,instr_iterator> iterator;
214 bundle_iterator<const MachineInstr,const_instr_iterator> const_iterator;
215 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
216 typedef std::reverse_iterator<iterator> reverse_iterator;
219 unsigned size() const { return (unsigned)Insts.size(); }
220 bool empty() const { return Insts.empty(); }
222 MachineInstr& front() { return Insts.front(); }
223 MachineInstr& back() { return Insts.back(); }
224 const MachineInstr& front() const { return Insts.front(); }
225 const MachineInstr& back() const { return Insts.back(); }
227 instr_iterator instr_begin() { return Insts.begin(); }
228 const_instr_iterator instr_begin() const { return Insts.begin(); }
229 instr_iterator instr_end() { return Insts.end(); }
230 const_instr_iterator instr_end() const { return Insts.end(); }
231 reverse_instr_iterator instr_rbegin() { return Insts.rbegin(); }
232 const_reverse_instr_iterator instr_rbegin() const { return Insts.rbegin(); }
233 reverse_instr_iterator instr_rend () { return Insts.rend(); }
234 const_reverse_instr_iterator instr_rend () const { return Insts.rend(); }
236 iterator begin() { return instr_begin(); }
237 const_iterator begin() const { return instr_begin(); }
238 iterator end () { return instr_end(); }
239 const_iterator end () const { return instr_end(); }
240 reverse_iterator rbegin() { return instr_rbegin(); }
241 const_reverse_iterator rbegin() const { return instr_rbegin(); }
242 reverse_iterator rend () { return instr_rend(); }
243 const_reverse_iterator rend () const { return instr_rend(); }
246 // Machine-CFG iterators
247 typedef std::vector<MachineBasicBlock *>::iterator pred_iterator;
248 typedef std::vector<MachineBasicBlock *>::const_iterator const_pred_iterator;
249 typedef std::vector<MachineBasicBlock *>::iterator succ_iterator;
250 typedef std::vector<MachineBasicBlock *>::const_iterator const_succ_iterator;
251 typedef std::vector<MachineBasicBlock *>::reverse_iterator
252 pred_reverse_iterator;
253 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator
254 const_pred_reverse_iterator;
255 typedef std::vector<MachineBasicBlock *>::reverse_iterator
256 succ_reverse_iterator;
257 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator
258 const_succ_reverse_iterator;
259 pred_iterator pred_begin() { return Predecessors.begin(); }
260 const_pred_iterator pred_begin() const { return Predecessors.begin(); }
261 pred_iterator pred_end() { return Predecessors.end(); }
262 const_pred_iterator pred_end() const { return Predecessors.end(); }
263 pred_reverse_iterator pred_rbegin()
264 { return Predecessors.rbegin();}
265 const_pred_reverse_iterator pred_rbegin() const
266 { return Predecessors.rbegin();}
267 pred_reverse_iterator pred_rend()
268 { return Predecessors.rend(); }
269 const_pred_reverse_iterator pred_rend() const
270 { return Predecessors.rend(); }
271 unsigned pred_size() const {
272 return (unsigned)Predecessors.size();
274 bool pred_empty() const { return Predecessors.empty(); }
275 succ_iterator succ_begin() { return Successors.begin(); }
276 const_succ_iterator succ_begin() const { return Successors.begin(); }
277 succ_iterator succ_end() { return Successors.end(); }
278 const_succ_iterator succ_end() const { return Successors.end(); }
279 succ_reverse_iterator succ_rbegin()
280 { return Successors.rbegin(); }
281 const_succ_reverse_iterator succ_rbegin() const
282 { return Successors.rbegin(); }
283 succ_reverse_iterator succ_rend()
284 { return Successors.rend(); }
285 const_succ_reverse_iterator succ_rend() const
286 { return Successors.rend(); }
287 unsigned succ_size() const {
288 return (unsigned)Successors.size();
290 bool succ_empty() const { return Successors.empty(); }
292 inline iterator_range<pred_iterator> predecessors() {
293 return iterator_range<pred_iterator>(pred_begin(), pred_end());
295 inline iterator_range<const_pred_iterator> predecessors() const {
296 return iterator_range<const_pred_iterator>(pred_begin(), pred_end());
298 inline iterator_range<succ_iterator> successors() {
299 return iterator_range<succ_iterator>(succ_begin(), succ_end());
301 inline iterator_range<const_succ_iterator> successors() const {
302 return iterator_range<const_succ_iterator>(succ_begin(), succ_end());
305 // LiveIn management methods.
307 /// addLiveIn - Add the specified register as a live in. Note that it
308 /// is an error to add the same register to the same set more than once.
309 void addLiveIn(unsigned Reg) { LiveIns.push_back(Reg); }
311 /// Add PhysReg as live in to this block, and ensure that there is a copy of
312 /// PhysReg to a virtual register of class RC. Return the virtual register
313 /// that is a copy of the live in PhysReg.
314 unsigned addLiveIn(unsigned PhysReg, const TargetRegisterClass *RC);
316 /// removeLiveIn - Remove the specified register from the live in set.
318 void removeLiveIn(unsigned Reg);
320 /// isLiveIn - Return true if the specified register is in the live in set.
322 bool isLiveIn(unsigned Reg) const;
324 // Iteration support for live in sets. These sets are kept in sorted
325 // order by their register number.
326 typedef std::vector<unsigned>::const_iterator livein_iterator;
327 livein_iterator livein_begin() const { return LiveIns.begin(); }
328 livein_iterator livein_end() const { return LiveIns.end(); }
329 bool livein_empty() const { return LiveIns.empty(); }
331 /// getAlignment - Return alignment of the basic block.
332 /// The alignment is specified as log2(bytes).
334 unsigned getAlignment() const { return Alignment; }
336 /// setAlignment - Set alignment of the basic block.
337 /// The alignment is specified as log2(bytes).
339 void setAlignment(unsigned Align) { Alignment = Align; }
341 /// isLandingPad - Returns true if the block is a landing pad. That is
342 /// this basic block is entered via an exception handler.
343 bool isLandingPad() const { return IsLandingPad; }
345 /// setIsLandingPad - Indicates the block is a landing pad. That is
346 /// this basic block is entered via an exception handler.
347 void setIsLandingPad(bool V = true) { IsLandingPad = V; }
349 /// getLandingPadSuccessor - If this block has a successor that is a landing
350 /// pad, return it. Otherwise return NULL.
351 const MachineBasicBlock *getLandingPadSuccessor() const;
353 // Code Layout methods.
355 /// moveBefore/moveAfter - move 'this' block before or after the specified
356 /// block. This only moves the block, it does not modify the CFG or adjust
357 /// potential fall-throughs at the end of the block.
358 void moveBefore(MachineBasicBlock *NewAfter);
359 void moveAfter(MachineBasicBlock *NewBefore);
361 /// updateTerminator - Update the terminator instructions in block to account
362 /// for changes to the layout. If the block previously used a fallthrough,
363 /// it may now need a branch, and if it previously used branching it may now
364 /// be able to use a fallthrough.
365 void updateTerminator();
367 // Machine-CFG mutators
369 /// addSuccessor - Add succ as a successor of this MachineBasicBlock.
370 /// The Predecessors list of succ is automatically updated. WEIGHT
371 /// parameter is stored in Weights list and it may be used by
372 /// MachineBranchProbabilityInfo analysis to calculate branch probability.
374 /// Note that duplicate Machine CFG edges are not allowed.
376 void addSuccessor(MachineBasicBlock *succ, uint32_t weight = 0);
378 /// Set successor weight of a given iterator.
379 void setSuccWeight(succ_iterator I, uint32_t weight);
381 /// removeSuccessor - Remove successor from the successors list of this
382 /// MachineBasicBlock. The Predecessors list of succ is automatically updated.
384 void removeSuccessor(MachineBasicBlock *succ);
386 /// removeSuccessor - Remove specified successor from the successors list of
387 /// this MachineBasicBlock. The Predecessors list of succ is automatically
388 /// updated. Return the iterator to the element after the one removed.
390 succ_iterator removeSuccessor(succ_iterator I);
392 /// replaceSuccessor - Replace successor OLD with NEW and update weight info.
394 void replaceSuccessor(MachineBasicBlock *Old, MachineBasicBlock *New);
397 /// transferSuccessors - Transfers all the successors from MBB to this
398 /// machine basic block (i.e., copies all the successors fromMBB and
399 /// remove all the successors from fromMBB).
400 void transferSuccessors(MachineBasicBlock *fromMBB);
402 /// transferSuccessorsAndUpdatePHIs - Transfers all the successors, as
403 /// in transferSuccessors, and update PHI operands in the successor blocks
404 /// which refer to fromMBB to refer to this.
405 void transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB);
407 /// isPredecessor - Return true if the specified MBB is a predecessor of this
409 bool isPredecessor(const MachineBasicBlock *MBB) const;
411 /// isSuccessor - Return true if the specified MBB is a successor of this
413 bool isSuccessor(const MachineBasicBlock *MBB) const;
415 /// isLayoutSuccessor - Return true if the specified MBB will be emitted
416 /// immediately after this block, such that if this block exits by
417 /// falling through, control will transfer to the specified MBB. Note
418 /// that MBB need not be a successor at all, for example if this block
419 /// ends with an unconditional branch to some other block.
420 bool isLayoutSuccessor(const MachineBasicBlock *MBB) const;
422 /// canFallThrough - Return true if the block can implicitly transfer
423 /// control to the block after it by falling off the end of it. This should
424 /// return false if it can reach the block after it, but it uses an explicit
425 /// branch to do so (e.g., a table jump). True is a conservative answer.
426 bool canFallThrough();
428 /// Returns a pointer to the first instruction in this block that is not a
429 /// PHINode instruction. When adding instructions to the beginning of the
430 /// basic block, they should be added before the returned value, not before
431 /// the first instruction, which might be PHI.
432 /// Returns end() is there's no non-PHI instruction.
433 iterator getFirstNonPHI();
435 /// SkipPHIsAndLabels - Return the first instruction in MBB after I that is
436 /// not a PHI or a label. This is the correct point to insert copies at the
437 /// beginning of a basic block.
438 iterator SkipPHIsAndLabels(iterator I);
440 /// getFirstTerminator - returns an iterator to the first terminator
441 /// instruction of this basic block. If a terminator does not exist,
443 iterator getFirstTerminator();
444 const_iterator getFirstTerminator() const;
446 /// getFirstInstrTerminator - Same getFirstTerminator but it ignores bundles
447 /// and return an instr_iterator instead.
448 instr_iterator getFirstInstrTerminator();
450 /// getLastNonDebugInstr - returns an iterator to the last non-debug
451 /// instruction in the basic block, or end()
452 iterator getLastNonDebugInstr();
453 const_iterator getLastNonDebugInstr() const;
455 /// SplitCriticalEdge - Split the critical edge from this block to the
456 /// given successor block, and return the newly created block, or null
457 /// if splitting is not possible.
459 /// This function updates LiveVariables, MachineDominatorTree, and
460 /// MachineLoopInfo, as applicable.
461 MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P);
463 void pop_front() { Insts.pop_front(); }
464 void pop_back() { Insts.pop_back(); }
465 void push_back(MachineInstr *MI) { Insts.push_back(MI); }
467 /// Insert MI into the instruction list before I, possibly inside a bundle.
469 /// If the insertion point is inside a bundle, MI will be added to the bundle,
470 /// otherwise MI will not be added to any bundle. That means this function
471 /// alone can't be used to prepend or append instructions to bundles. See
472 /// MIBundleBuilder::insert() for a more reliable way of doing that.
473 instr_iterator insert(instr_iterator I, MachineInstr *M);
475 /// Insert a range of instructions into the instruction list before I.
476 template<typename IT>
477 void insert(iterator I, IT S, IT E) {
478 Insts.insert(I.getInstrIterator(), S, E);
481 /// Insert MI into the instruction list before I.
482 iterator insert(iterator I, MachineInstr *MI) {
483 assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
484 "Cannot insert instruction with bundle flags");
485 return Insts.insert(I.getInstrIterator(), MI);
488 /// Insert MI into the instruction list after I.
489 iterator insertAfter(iterator I, MachineInstr *MI) {
490 assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
491 "Cannot insert instruction with bundle flags");
492 return Insts.insertAfter(I.getInstrIterator(), MI);
495 /// Remove an instruction from the instruction list and delete it.
497 /// If the instruction is part of a bundle, the other instructions in the
498 /// bundle will still be bundled after removing the single instruction.
499 instr_iterator erase(instr_iterator I);
501 /// Remove an instruction from the instruction list and delete it.
503 /// If the instruction is part of a bundle, the other instructions in the
504 /// bundle will still be bundled after removing the single instruction.
505 instr_iterator erase_instr(MachineInstr *I) {
506 return erase(instr_iterator(I));
509 /// Remove a range of instructions from the instruction list and delete them.
510 iterator erase(iterator I, iterator E) {
511 return Insts.erase(I.getInstrIterator(), E.getInstrIterator());
514 /// Remove an instruction or bundle from the instruction list and delete it.
516 /// If I points to a bundle of instructions, they are all erased.
517 iterator erase(iterator I) {
518 return erase(I, std::next(I));
521 /// Remove an instruction from the instruction list and delete it.
523 /// If I is the head of a bundle of instructions, the whole bundle will be
525 iterator erase(MachineInstr *I) {
526 return erase(iterator(I));
529 /// Remove the unbundled instruction from the instruction list without
532 /// This function can not be used to remove bundled instructions, use
533 /// remove_instr to remove individual instructions from a bundle.
534 MachineInstr *remove(MachineInstr *I) {
535 assert(!I->isBundled() && "Cannot remove bundled instructions");
536 return Insts.remove(I);
539 /// Remove the possibly bundled instruction from the instruction list
540 /// without deleting it.
542 /// If the instruction is part of a bundle, the other instructions in the
543 /// bundle will still be bundled after removing the single instruction.
544 MachineInstr *remove_instr(MachineInstr *I);
550 /// Take an instruction from MBB 'Other' at the position From, and insert it
551 /// into this MBB right before 'Where'.
553 /// If From points to a bundle of instructions, the whole bundle is moved.
554 void splice(iterator Where, MachineBasicBlock *Other, iterator From) {
555 // The range splice() doesn't allow noop moves, but this one does.
557 splice(Where, Other, From, std::next(From));
560 /// Take a block of instructions from MBB 'Other' in the range [From, To),
561 /// and insert them into this MBB right before 'Where'.
563 /// The instruction at 'Where' must not be included in the range of
564 /// instructions to move.
565 void splice(iterator Where, MachineBasicBlock *Other,
566 iterator From, iterator To) {
567 Insts.splice(Where.getInstrIterator(), Other->Insts,
568 From.getInstrIterator(), To.getInstrIterator());
571 /// removeFromParent - This method unlinks 'this' from the containing
572 /// function, and returns it, but does not delete it.
573 MachineBasicBlock *removeFromParent();
575 /// eraseFromParent - This method unlinks 'this' from the containing
576 /// function and deletes it.
577 void eraseFromParent();
579 /// ReplaceUsesOfBlockWith - Given a machine basic block that branched to
580 /// 'Old', change the code and CFG so that it branches to 'New' instead.
581 void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New);
583 /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in
584 /// the CFG to be inserted. If we have proven that MBB can only branch to
585 /// DestA and DestB, remove any other MBB successors from the CFG. DestA and
586 /// DestB can be null. Besides DestA and DestB, retain other edges leading
587 /// to LandingPads (currently there can be only one; we don't check or require
588 /// that here). Note it is possible that DestA and/or DestB are LandingPads.
589 bool CorrectExtraCFGEdges(MachineBasicBlock *DestA,
590 MachineBasicBlock *DestB,
593 /// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping
594 /// any DBG_VALUE instructions. Return UnknownLoc if there is none.
595 DebugLoc findDebugLoc(instr_iterator MBBI);
596 DebugLoc findDebugLoc(iterator MBBI) {
597 return findDebugLoc(MBBI.getInstrIterator());
600 /// Possible outcome of a register liveness query to computeRegisterLiveness()
601 enum LivenessQueryResult {
602 LQR_Live, ///< Register is known to be live.
603 LQR_OverlappingLive, ///< Register itself is not live, but some overlapping
605 LQR_Dead, ///< Register is known to be dead.
606 LQR_Unknown ///< Register liveness not decidable from local
610 /// computeRegisterLiveness - Return whether (physical) register \c Reg
611 /// has been <def>ined and not <kill>ed as of just before \c MI.
613 /// Search is localised to a neighborhood of
614 /// \c Neighborhood instructions before (searching for defs or kills) and
615 /// Neighborhood instructions after (searching just for defs) MI.
617 /// \c Reg must be a physical register.
618 LivenessQueryResult computeRegisterLiveness(const TargetRegisterInfo *TRI,
619 unsigned Reg, MachineInstr *MI,
620 unsigned Neighborhood=10);
622 // Debugging methods.
624 void print(raw_ostream &OS, SlotIndexes* = 0) const;
626 // Printing method used by LoopInfo.
627 void printAsOperand(raw_ostream &OS, bool PrintType = true);
629 /// getNumber - MachineBasicBlocks are uniquely numbered at the function
630 /// level, unless they're not in a MachineFunction yet, in which case this
633 int getNumber() const { return Number; }
634 void setNumber(int N) { Number = N; }
636 /// getSymbol - Return the MCSymbol for this basic block.
638 MCSymbol *getSymbol() const;
642 /// getWeightIterator - Return weight iterator corresponding to the I
643 /// successor iterator.
644 weight_iterator getWeightIterator(succ_iterator I);
645 const_weight_iterator getWeightIterator(const_succ_iterator I) const;
647 friend class MachineBranchProbabilityInfo;
649 /// getSuccWeight - Return weight of the edge from this block to MBB. This
650 /// method should NOT be called directly, but by using getEdgeWeight method
651 /// from MachineBranchProbabilityInfo class.
652 uint32_t getSuccWeight(const_succ_iterator Succ) const;
655 // Methods used to maintain doubly linked list of blocks...
656 friend struct ilist_traits<MachineBasicBlock>;
658 // Machine-CFG mutators
660 /// addPredecessor - Remove pred as a predecessor of this MachineBasicBlock.
661 /// Don't do this unless you know what you're doing, because it doesn't
662 /// update pred's successors list. Use pred->addSuccessor instead.
664 void addPredecessor(MachineBasicBlock *pred);
666 /// removePredecessor - Remove pred as a predecessor of this
667 /// MachineBasicBlock. Don't do this unless you know what you're
668 /// doing, because it doesn't update pred's successors list. Use
669 /// pred->removeSuccessor instead.
671 void removePredecessor(MachineBasicBlock *pred);
674 raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB);
676 // This is useful when building IndexedMaps keyed on basic block pointers.
677 struct MBB2NumberFunctor :
678 public std::unary_function<const MachineBasicBlock*, unsigned> {
679 unsigned operator()(const MachineBasicBlock *MBB) const {
680 return MBB->getNumber();
684 //===--------------------------------------------------------------------===//
685 // GraphTraits specializations for machine basic block graphs (machine-CFGs)
686 //===--------------------------------------------------------------------===//
688 // Provide specializations of GraphTraits to be able to treat a
689 // MachineFunction as a graph of MachineBasicBlocks...
692 template <> struct GraphTraits<MachineBasicBlock *> {
693 typedef MachineBasicBlock NodeType;
694 typedef MachineBasicBlock::succ_iterator ChildIteratorType;
696 static NodeType *getEntryNode(MachineBasicBlock *BB) { return BB; }
697 static inline ChildIteratorType child_begin(NodeType *N) {
698 return N->succ_begin();
700 static inline ChildIteratorType child_end(NodeType *N) {
701 return N->succ_end();
705 template <> struct GraphTraits<const MachineBasicBlock *> {
706 typedef const MachineBasicBlock NodeType;
707 typedef MachineBasicBlock::const_succ_iterator ChildIteratorType;
709 static NodeType *getEntryNode(const MachineBasicBlock *BB) { return BB; }
710 static inline ChildIteratorType child_begin(NodeType *N) {
711 return N->succ_begin();
713 static inline ChildIteratorType child_end(NodeType *N) {
714 return N->succ_end();
718 // Provide specializations of GraphTraits to be able to treat a
719 // MachineFunction as a graph of MachineBasicBlocks... and to walk it
720 // in inverse order. Inverse order for a function is considered
721 // to be when traversing the predecessor edges of a MBB
722 // instead of the successor edges.
724 template <> struct GraphTraits<Inverse<MachineBasicBlock*> > {
725 typedef MachineBasicBlock NodeType;
726 typedef MachineBasicBlock::pred_iterator ChildIteratorType;
727 static NodeType *getEntryNode(Inverse<MachineBasicBlock *> G) {
730 static inline ChildIteratorType child_begin(NodeType *N) {
731 return N->pred_begin();
733 static inline ChildIteratorType child_end(NodeType *N) {
734 return N->pred_end();
738 template <> struct GraphTraits<Inverse<const MachineBasicBlock*> > {
739 typedef const MachineBasicBlock NodeType;
740 typedef MachineBasicBlock::const_pred_iterator ChildIteratorType;
741 static NodeType *getEntryNode(Inverse<const MachineBasicBlock*> G) {
744 static inline ChildIteratorType child_begin(NodeType *N) {
745 return N->pred_begin();
747 static inline ChildIteratorType child_end(NodeType *N) {
748 return N->pred_end();
754 /// MachineInstrSpan provides an interface to get an iteration range
755 /// containing the instruction it was initialized with, along with all
756 /// those instructions inserted prior to or following that instruction
757 /// at some point after the MachineInstrSpan is constructed.
758 class MachineInstrSpan {
759 MachineBasicBlock &MBB;
760 MachineBasicBlock::iterator I, B, E;
762 MachineInstrSpan(MachineBasicBlock::iterator I)
763 : MBB(*I->getParent()),
765 B(I == MBB.begin() ? MBB.end() : std::prev(I)),
768 MachineBasicBlock::iterator begin() {
769 return B == MBB.end() ? MBB.begin() : std::next(B);
771 MachineBasicBlock::iterator end() { return E; }
772 bool empty() { return begin() == end(); }
774 MachineBasicBlock::iterator getInitial() { return I; }
777 } // End llvm namespace