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/ADT/iterator_range.h"
19 #include "llvm/CodeGen/MachineInstrBundleIterator.h"
20 #include "llvm/CodeGen/MachineInstr.h"
21 #include "llvm/Support/BranchProbability.h"
22 #include "llvm/MC/LaneBitmask.h"
23 #include "llvm/MC/MCRegisterInfo.h"
24 #include "llvm/Support/DataTypes.h"
31 class MachineFunction;
37 class MachineBranchProbabilityInfo;
39 template <> struct ilist_traits<MachineInstr> {
41 friend class MachineBasicBlock; // Set by the owning MachineBasicBlock.
42 MachineBasicBlock *Parent;
44 typedef simple_ilist<MachineInstr, ilist_sentinel_tracking<true>>::iterator
48 void addNodeToList(MachineInstr *N);
49 void removeNodeFromList(MachineInstr *N);
50 void transferNodesFromList(ilist_traits &OldList, instr_iterator First,
53 void deleteNode(MachineInstr *MI);
56 class MachineBasicBlock
57 : public ilist_node_with_parent<MachineBasicBlock, MachineFunction> {
59 /// Pair of physical register and lane mask.
60 /// This is not simply a std::pair typedef because the members should be named
61 /// clearly as they both have an integer type.
62 struct RegisterMaskPair {
67 RegisterMaskPair(MCPhysReg PhysReg, LaneBitmask LaneMask)
68 : PhysReg(PhysReg), LaneMask(LaneMask) {}
72 typedef ilist<MachineInstr, ilist_sentinel_tracking<true>> Instructions;
76 MachineFunction *xParent;
78 /// Keep track of the predecessor / successor basic blocks.
79 std::vector<MachineBasicBlock *> Predecessors;
80 std::vector<MachineBasicBlock *> Successors;
82 /// Keep track of the probabilities to the successors. This vector has the
83 /// same order as Successors, or it is empty if we don't use it (disable
85 std::vector<BranchProbability> Probs;
86 typedef std::vector<BranchProbability>::iterator probability_iterator;
87 typedef std::vector<BranchProbability>::const_iterator
88 const_probability_iterator;
90 /// Keep track of the physical registers that are livein of the basicblock.
91 typedef std::vector<RegisterMaskPair> LiveInVector;
94 /// Alignment of the basic block. Zero if the basic block does not need to be
95 /// aligned. The alignment is specified as log2(bytes).
96 unsigned Alignment = 0;
98 /// Indicate that this basic block is entered via an exception handler.
101 /// Indicate that this basic block is potentially the target of an indirect
103 bool AddressTaken = false;
105 /// Indicate that this basic block is the entry block of an EH funclet.
106 bool IsEHFuncletEntry = false;
108 /// Indicate that this basic block is the entry block of a cleanup funclet.
109 bool IsCleanupFuncletEntry = false;
111 /// \brief since getSymbol is a relatively heavy-weight operation, the symbol
112 /// is only computed once and is cached.
113 mutable MCSymbol *CachedMCSymbol = nullptr;
115 // Intrusive list support
116 MachineBasicBlock() {}
118 explicit MachineBasicBlock(MachineFunction &MF, const BasicBlock *BB);
120 ~MachineBasicBlock();
122 // MachineBasicBlocks are allocated and owned by MachineFunction.
123 friend class MachineFunction;
126 /// Return the LLVM basic block that this instance corresponded to originally.
127 /// Note that this may be NULL if this instance does not correspond directly
128 /// to an LLVM basic block.
129 const BasicBlock *getBasicBlock() const { return BB; }
131 /// Return the name of the corresponding LLVM basic block, or "(null)".
132 StringRef getName() const;
134 /// Return a formatted string to identify this block and its parent function.
135 std::string getFullName() const;
137 /// Test whether this block is potentially the target of an indirect branch.
138 bool hasAddressTaken() const { return AddressTaken; }
140 /// Set this block to reflect that it potentially is the target of an indirect
142 void setHasAddressTaken() { AddressTaken = true; }
144 /// Return the MachineFunction containing this basic block.
145 const MachineFunction *getParent() const { return xParent; }
146 MachineFunction *getParent() { return xParent; }
148 typedef Instructions::iterator instr_iterator;
149 typedef Instructions::const_iterator const_instr_iterator;
150 typedef Instructions::reverse_iterator reverse_instr_iterator;
151 typedef Instructions::const_reverse_iterator const_reverse_instr_iterator;
153 typedef MachineInstrBundleIterator<MachineInstr> iterator;
154 typedef MachineInstrBundleIterator<const MachineInstr> const_iterator;
155 typedef MachineInstrBundleIterator<MachineInstr, true> reverse_iterator;
156 typedef MachineInstrBundleIterator<const MachineInstr, true>
157 const_reverse_iterator;
159 unsigned size() const { return (unsigned)Insts.size(); }
160 bool empty() const { return Insts.empty(); }
162 MachineInstr &instr_front() { return Insts.front(); }
163 MachineInstr &instr_back() { return Insts.back(); }
164 const MachineInstr &instr_front() const { return Insts.front(); }
165 const MachineInstr &instr_back() const { return Insts.back(); }
167 MachineInstr &front() { return Insts.front(); }
168 MachineInstr &back() { return *--end(); }
169 const MachineInstr &front() const { return Insts.front(); }
170 const MachineInstr &back() const { return *--end(); }
172 instr_iterator instr_begin() { return Insts.begin(); }
173 const_instr_iterator instr_begin() const { return Insts.begin(); }
174 instr_iterator instr_end() { return Insts.end(); }
175 const_instr_iterator instr_end() const { return Insts.end(); }
176 reverse_instr_iterator instr_rbegin() { return Insts.rbegin(); }
177 const_reverse_instr_iterator instr_rbegin() const { return Insts.rbegin(); }
178 reverse_instr_iterator instr_rend () { return Insts.rend(); }
179 const_reverse_instr_iterator instr_rend () const { return Insts.rend(); }
181 typedef iterator_range<instr_iterator> instr_range;
182 typedef iterator_range<const_instr_iterator> const_instr_range;
183 instr_range instrs() { return instr_range(instr_begin(), instr_end()); }
184 const_instr_range instrs() const {
185 return const_instr_range(instr_begin(), instr_end());
188 iterator begin() { return instr_begin(); }
189 const_iterator begin() const { return instr_begin(); }
190 iterator end () { return instr_end(); }
191 const_iterator end () const { return instr_end(); }
192 reverse_iterator rbegin() {
193 return reverse_iterator::getAtBundleBegin(instr_rbegin());
195 const_reverse_iterator rbegin() const {
196 return const_reverse_iterator::getAtBundleBegin(instr_rbegin());
198 reverse_iterator rend() { return reverse_iterator(instr_rend()); }
199 const_reverse_iterator rend() const {
200 return const_reverse_iterator(instr_rend());
203 /// Support for MachineInstr::getNextNode().
204 static Instructions MachineBasicBlock::*getSublistAccess(MachineInstr *) {
205 return &MachineBasicBlock::Insts;
208 inline iterator_range<iterator> terminators() {
209 return make_range(getFirstTerminator(), end());
211 inline iterator_range<const_iterator> terminators() const {
212 return make_range(getFirstTerminator(), end());
215 // Machine-CFG iterators
216 typedef std::vector<MachineBasicBlock *>::iterator pred_iterator;
217 typedef std::vector<MachineBasicBlock *>::const_iterator const_pred_iterator;
218 typedef std::vector<MachineBasicBlock *>::iterator succ_iterator;
219 typedef std::vector<MachineBasicBlock *>::const_iterator const_succ_iterator;
220 typedef std::vector<MachineBasicBlock *>::reverse_iterator
221 pred_reverse_iterator;
222 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator
223 const_pred_reverse_iterator;
224 typedef std::vector<MachineBasicBlock *>::reverse_iterator
225 succ_reverse_iterator;
226 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator
227 const_succ_reverse_iterator;
228 pred_iterator pred_begin() { return Predecessors.begin(); }
229 const_pred_iterator pred_begin() const { return Predecessors.begin(); }
230 pred_iterator pred_end() { return Predecessors.end(); }
231 const_pred_iterator pred_end() const { return Predecessors.end(); }
232 pred_reverse_iterator pred_rbegin()
233 { return Predecessors.rbegin();}
234 const_pred_reverse_iterator pred_rbegin() const
235 { return Predecessors.rbegin();}
236 pred_reverse_iterator pred_rend()
237 { return Predecessors.rend(); }
238 const_pred_reverse_iterator pred_rend() const
239 { return Predecessors.rend(); }
240 unsigned pred_size() const {
241 return (unsigned)Predecessors.size();
243 bool pred_empty() const { return Predecessors.empty(); }
244 succ_iterator succ_begin() { return Successors.begin(); }
245 const_succ_iterator succ_begin() const { return Successors.begin(); }
246 succ_iterator succ_end() { return Successors.end(); }
247 const_succ_iterator succ_end() const { return Successors.end(); }
248 succ_reverse_iterator succ_rbegin()
249 { return Successors.rbegin(); }
250 const_succ_reverse_iterator succ_rbegin() const
251 { return Successors.rbegin(); }
252 succ_reverse_iterator succ_rend()
253 { return Successors.rend(); }
254 const_succ_reverse_iterator succ_rend() const
255 { return Successors.rend(); }
256 unsigned succ_size() const {
257 return (unsigned)Successors.size();
259 bool succ_empty() const { return Successors.empty(); }
261 inline iterator_range<pred_iterator> predecessors() {
262 return make_range(pred_begin(), pred_end());
264 inline iterator_range<const_pred_iterator> predecessors() const {
265 return make_range(pred_begin(), pred_end());
267 inline iterator_range<succ_iterator> successors() {
268 return make_range(succ_begin(), succ_end());
270 inline iterator_range<const_succ_iterator> successors() const {
271 return make_range(succ_begin(), succ_end());
274 // LiveIn management methods.
276 /// Adds the specified register as a live in. Note that it is an error to add
277 /// the same register to the same set more than once unless the intention is
278 /// to call sortUniqueLiveIns after all registers are added.
279 void addLiveIn(MCPhysReg PhysReg,
280 LaneBitmask LaneMask = LaneBitmask::getAll()) {
281 LiveIns.push_back(RegisterMaskPair(PhysReg, LaneMask));
283 void addLiveIn(const RegisterMaskPair &RegMaskPair) {
284 LiveIns.push_back(RegMaskPair);
287 /// Sorts and uniques the LiveIns vector. It can be significantly faster to do
288 /// this than repeatedly calling isLiveIn before calling addLiveIn for every
289 /// LiveIn insertion.
290 void sortUniqueLiveIns();
292 /// Clear live in list.
295 /// Add PhysReg as live in to this block, and ensure that there is a copy of
296 /// PhysReg to a virtual register of class RC. Return the virtual register
297 /// that is a copy of the live in PhysReg.
298 unsigned addLiveIn(MCPhysReg PhysReg, const TargetRegisterClass *RC);
300 /// Remove the specified register from the live in set.
301 void removeLiveIn(MCPhysReg Reg,
302 LaneBitmask LaneMask = LaneBitmask::getAll());
304 /// Return true if the specified register is in the live in set.
305 bool isLiveIn(MCPhysReg Reg,
306 LaneBitmask LaneMask = LaneBitmask::getAll()) const;
308 // Iteration support for live in sets. These sets are kept in sorted
309 // order by their register number.
310 typedef LiveInVector::const_iterator livein_iterator;
312 /// Unlike livein_begin, this method does not check that the liveness
313 /// information is accurate. Still for debug purposes it may be useful
314 /// to have iterators that won't assert if the liveness information
316 livein_iterator livein_begin_dbg() const { return LiveIns.begin(); }
317 iterator_range<livein_iterator> liveins_dbg() const {
318 return make_range(livein_begin_dbg(), livein_end());
321 livein_iterator livein_begin() const;
322 livein_iterator livein_end() const { return LiveIns.end(); }
323 bool livein_empty() const { return LiveIns.empty(); }
324 iterator_range<livein_iterator> liveins() const {
325 return make_range(livein_begin(), livein_end());
328 /// Get the clobber mask for the start of this basic block. Funclets use this
329 /// to prevent register allocation across funclet transitions.
330 const uint32_t *getBeginClobberMask(const TargetRegisterInfo *TRI) const;
332 /// Get the clobber mask for the end of the basic block.
333 /// \see getBeginClobberMask()
334 const uint32_t *getEndClobberMask(const TargetRegisterInfo *TRI) const;
336 /// Return alignment of the basic block. The alignment is specified as
338 unsigned getAlignment() const { return Alignment; }
340 /// Set alignment of the basic block. The alignment is specified as
342 void setAlignment(unsigned Align) { Alignment = Align; }
344 /// Returns true if the block is a landing pad. That is this basic block is
345 /// entered via an exception handler.
346 bool isEHPad() const { return IsEHPad; }
348 /// Indicates the block is a landing pad. That is this basic block is entered
349 /// via an exception handler.
350 void setIsEHPad(bool V = true) { IsEHPad = V; }
352 bool hasEHPadSuccessor() const;
354 /// Returns true if this is the entry block of an EH funclet.
355 bool isEHFuncletEntry() const { return IsEHFuncletEntry; }
357 /// Indicates if this is the entry block of an EH funclet.
358 void setIsEHFuncletEntry(bool V = true) { IsEHFuncletEntry = V; }
360 /// Returns true if this is the entry block of a cleanup funclet.
361 bool isCleanupFuncletEntry() const { return IsCleanupFuncletEntry; }
363 /// Indicates if this is the entry block of a cleanup funclet.
364 void setIsCleanupFuncletEntry(bool V = true) { IsCleanupFuncletEntry = V; }
366 // Code Layout methods.
368 /// Move 'this' block before or after the specified block. This only moves
369 /// the block, it does not modify the CFG or adjust potential fall-throughs at
370 /// the end of the block.
371 void moveBefore(MachineBasicBlock *NewAfter);
372 void moveAfter(MachineBasicBlock *NewBefore);
374 /// Update the terminator instructions in block to account for changes to the
375 /// layout. If the block previously used a fallthrough, it may now need a
376 /// branch, and if it previously used branching it may now be able to use a
378 void updateTerminator();
380 // Machine-CFG mutators
382 /// Add Succ as a successor of this MachineBasicBlock. The Predecessors list
383 /// of Succ is automatically updated. PROB parameter is stored in
384 /// Probabilities list. The default probability is set as unknown. Mixing
385 /// known and unknown probabilities in successor list is not allowed. When all
386 /// successors have unknown probabilities, 1 / N is returned as the
387 /// probability for each successor, where N is the number of successors.
389 /// Note that duplicate Machine CFG edges are not allowed.
390 void addSuccessor(MachineBasicBlock *Succ,
391 BranchProbability Prob = BranchProbability::getUnknown());
393 /// Add Succ as a successor of this MachineBasicBlock. The Predecessors list
394 /// of Succ is automatically updated. The probability is not provided because
395 /// BPI is not available (e.g. -O0 is used), in which case edge probabilities
396 /// won't be used. Using this interface can save some space.
397 void addSuccessorWithoutProb(MachineBasicBlock *Succ);
399 /// Set successor probability of a given iterator.
400 void setSuccProbability(succ_iterator I, BranchProbability Prob);
402 /// Normalize probabilities of all successors so that the sum of them becomes
403 /// one. This is usually done when the current update on this MBB is done, and
404 /// the sum of its successors' probabilities is not guaranteed to be one. The
405 /// user is responsible for the correct use of this function.
406 /// MBB::removeSuccessor() has an option to do this automatically.
407 void normalizeSuccProbs() {
408 BranchProbability::normalizeProbabilities(Probs.begin(), Probs.end());
411 /// Validate successors' probabilities and check if the sum of them is
412 /// approximate one. This only works in DEBUG mode.
413 void validateSuccProbs() const;
415 /// Remove successor from the successors list of this MachineBasicBlock. The
416 /// Predecessors list of Succ is automatically updated.
417 /// If NormalizeSuccProbs is true, then normalize successors' probabilities
418 /// after the successor is removed.
419 void removeSuccessor(MachineBasicBlock *Succ,
420 bool NormalizeSuccProbs = false);
422 /// Remove specified successor from the successors list of this
423 /// MachineBasicBlock. The Predecessors list of Succ is automatically updated.
424 /// If NormalizeSuccProbs is true, then normalize successors' probabilities
425 /// after the successor is removed.
426 /// Return the iterator to the element after the one removed.
427 succ_iterator removeSuccessor(succ_iterator I,
428 bool NormalizeSuccProbs = false);
430 /// Replace successor OLD with NEW and update probability info.
431 void replaceSuccessor(MachineBasicBlock *Old, MachineBasicBlock *New);
433 /// Transfers all the successors from MBB to this machine basic block (i.e.,
434 /// copies all the successors FromMBB and remove all the successors from
436 void transferSuccessors(MachineBasicBlock *FromMBB);
438 /// Transfers all the successors, as in transferSuccessors, and update PHI
439 /// operands in the successor blocks which refer to FromMBB to refer to this.
440 void transferSuccessorsAndUpdatePHIs(MachineBasicBlock *FromMBB);
442 /// Return true if any of the successors have probabilities attached to them.
443 bool hasSuccessorProbabilities() const { return !Probs.empty(); }
445 /// Return true if the specified MBB is a predecessor of this block.
446 bool isPredecessor(const MachineBasicBlock *MBB) const;
448 /// Return true if the specified MBB is a successor of this block.
449 bool isSuccessor(const MachineBasicBlock *MBB) const;
451 /// Return true if the specified MBB will be emitted immediately after this
452 /// block, such that if this block exits by falling through, control will
453 /// transfer to the specified MBB. Note that MBB need not be a successor at
454 /// all, for example if this block ends with an unconditional branch to some
456 bool isLayoutSuccessor(const MachineBasicBlock *MBB) const;
458 /// Return true if the block can implicitly transfer control to the block
459 /// after it by falling off the end of it. This should return false if it can
460 /// reach the block after it, but it uses an explicit branch to do so (e.g., a
461 /// table jump). True is a conservative answer.
462 bool canFallThrough();
464 /// Returns a pointer to the first instruction in this block that is not a
465 /// PHINode instruction. When adding instructions to the beginning of the
466 /// basic block, they should be added before the returned value, not before
467 /// the first instruction, which might be PHI.
468 /// Returns end() is there's no non-PHI instruction.
469 iterator getFirstNonPHI();
471 /// Return the first instruction in MBB after I that is not a PHI or a label.
472 /// This is the correct point to insert lowered copies at the beginning of a
473 /// basic block that must be before any debugging information.
474 iterator SkipPHIsAndLabels(iterator I);
476 /// Return the first instruction in MBB after I that is not a PHI, label or
477 /// debug. This is the correct point to insert copies at the beginning of a
479 iterator SkipPHIsLabelsAndDebug(iterator I);
481 /// Returns an iterator to the first terminator instruction of this basic
482 /// block. If a terminator does not exist, it returns end().
483 iterator getFirstTerminator();
484 const_iterator getFirstTerminator() const {
485 return const_cast<MachineBasicBlock *>(this)->getFirstTerminator();
488 /// Same getFirstTerminator but it ignores bundles and return an
489 /// instr_iterator instead.
490 instr_iterator getFirstInstrTerminator();
492 /// Returns an iterator to the first non-debug instruction in the basic block,
494 iterator getFirstNonDebugInstr();
495 const_iterator getFirstNonDebugInstr() const {
496 return const_cast<MachineBasicBlock *>(this)->getFirstNonDebugInstr();
499 /// Returns an iterator to the last non-debug instruction in the basic block,
501 iterator getLastNonDebugInstr();
502 const_iterator getLastNonDebugInstr() const {
503 return const_cast<MachineBasicBlock *>(this)->getLastNonDebugInstr();
506 /// Convenience function that returns true if the block ends in a return
508 bool isReturnBlock() const {
509 return !empty() && back().isReturn();
512 /// Split the critical edge from this block to the given successor block, and
513 /// return the newly created block, or null if splitting is not possible.
515 /// This function updates LiveVariables, MachineDominatorTree, and
516 /// MachineLoopInfo, as applicable.
517 MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *Succ, Pass &P);
519 /// Check if the edge between this block and the given successor \p
520 /// Succ, can be split. If this returns true a subsequent call to
521 /// SplitCriticalEdge is guaranteed to return a valid basic block if
522 /// no changes occured in the meantime.
523 bool canSplitCriticalEdge(const MachineBasicBlock *Succ) const;
525 void pop_front() { Insts.pop_front(); }
526 void pop_back() { Insts.pop_back(); }
527 void push_back(MachineInstr *MI) { Insts.push_back(MI); }
529 /// Insert MI into the instruction list before I, possibly inside a bundle.
531 /// If the insertion point is inside a bundle, MI will be added to the bundle,
532 /// otherwise MI will not be added to any bundle. That means this function
533 /// alone can't be used to prepend or append instructions to bundles. See
534 /// MIBundleBuilder::insert() for a more reliable way of doing that.
535 instr_iterator insert(instr_iterator I, MachineInstr *M);
537 /// Insert a range of instructions into the instruction list before I.
538 template<typename IT>
539 void insert(iterator I, IT S, IT E) {
540 assert((I == end() || I->getParent() == this) &&
541 "iterator points outside of basic block");
542 Insts.insert(I.getInstrIterator(), S, E);
545 /// Insert MI into the instruction list before I.
546 iterator insert(iterator I, MachineInstr *MI) {
547 assert((I == end() || I->getParent() == this) &&
548 "iterator points outside of basic block");
549 assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
550 "Cannot insert instruction with bundle flags");
551 return Insts.insert(I.getInstrIterator(), MI);
554 /// Insert MI into the instruction list after I.
555 iterator insertAfter(iterator I, MachineInstr *MI) {
556 assert((I == end() || I->getParent() == this) &&
557 "iterator points outside of basic block");
558 assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
559 "Cannot insert instruction with bundle flags");
560 return Insts.insertAfter(I.getInstrIterator(), MI);
563 /// Remove an instruction from the instruction list and delete it.
565 /// If the instruction is part of a bundle, the other instructions in the
566 /// bundle will still be bundled after removing the single instruction.
567 instr_iterator erase(instr_iterator I);
569 /// Remove an instruction from the instruction list and delete it.
571 /// If the instruction is part of a bundle, the other instructions in the
572 /// bundle will still be bundled after removing the single instruction.
573 instr_iterator erase_instr(MachineInstr *I) {
574 return erase(instr_iterator(I));
577 /// Remove a range of instructions from the instruction list and delete them.
578 iterator erase(iterator I, iterator E) {
579 return Insts.erase(I.getInstrIterator(), E.getInstrIterator());
582 /// Remove an instruction or bundle from the instruction list and delete it.
584 /// If I points to a bundle of instructions, they are all erased.
585 iterator erase(iterator I) {
586 return erase(I, std::next(I));
589 /// Remove an instruction from the instruction list and delete it.
591 /// If I is the head of a bundle of instructions, the whole bundle will be
593 iterator erase(MachineInstr *I) {
594 return erase(iterator(I));
597 /// Remove the unbundled instruction from the instruction list without
600 /// This function can not be used to remove bundled instructions, use
601 /// remove_instr to remove individual instructions from a bundle.
602 MachineInstr *remove(MachineInstr *I) {
603 assert(!I->isBundled() && "Cannot remove bundled instructions");
604 return Insts.remove(instr_iterator(I));
607 /// Remove the possibly bundled instruction from the instruction list
608 /// without deleting it.
610 /// If the instruction is part of a bundle, the other instructions in the
611 /// bundle will still be bundled after removing the single instruction.
612 MachineInstr *remove_instr(MachineInstr *I);
618 /// Take an instruction from MBB 'Other' at the position From, and insert it
619 /// into this MBB right before 'Where'.
621 /// If From points to a bundle of instructions, the whole bundle is moved.
622 void splice(iterator Where, MachineBasicBlock *Other, iterator From) {
623 // The range splice() doesn't allow noop moves, but this one does.
625 splice(Where, Other, From, std::next(From));
628 /// Take a block of instructions from MBB 'Other' in the range [From, To),
629 /// and insert them into this MBB right before 'Where'.
631 /// The instruction at 'Where' must not be included in the range of
632 /// instructions to move.
633 void splice(iterator Where, MachineBasicBlock *Other,
634 iterator From, iterator To) {
635 Insts.splice(Where.getInstrIterator(), Other->Insts,
636 From.getInstrIterator(), To.getInstrIterator());
639 /// This method unlinks 'this' from the containing function, and returns it,
640 /// but does not delete it.
641 MachineBasicBlock *removeFromParent();
643 /// This method unlinks 'this' from the containing function and deletes it.
644 void eraseFromParent();
646 /// Given a machine basic block that branched to 'Old', change the code and
647 /// CFG so that it branches to 'New' instead.
648 void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New);
650 /// Various pieces of code can cause excess edges in the CFG to be inserted.
651 /// If we have proven that MBB can only branch to DestA and DestB, remove any
652 /// other MBB successors from the CFG. DestA and DestB can be null. Besides
653 /// DestA and DestB, retain other edges leading to LandingPads (currently
654 /// there can be only one; we don't check or require that here). Note it is
655 /// possible that DestA and/or DestB are LandingPads.
656 bool CorrectExtraCFGEdges(MachineBasicBlock *DestA,
657 MachineBasicBlock *DestB,
660 /// Find the next valid DebugLoc starting at MBBI, skipping any DBG_VALUE
661 /// instructions. Return UnknownLoc if there is none.
662 DebugLoc findDebugLoc(instr_iterator MBBI);
663 DebugLoc findDebugLoc(iterator MBBI) {
664 return findDebugLoc(MBBI.getInstrIterator());
667 /// Possible outcome of a register liveness query to computeRegisterLiveness()
668 enum LivenessQueryResult {
669 LQR_Live, ///< Register is known to be (at least partially) live.
670 LQR_Dead, ///< Register is known to be fully dead.
671 LQR_Unknown ///< Register liveness not decidable from local neighborhood.
674 /// Return whether (physical) register \p Reg has been <def>ined and not
675 /// <kill>ed as of just before \p Before.
677 /// Search is localised to a neighborhood of \p Neighborhood instructions
678 /// before (searching for defs or kills) and \p Neighborhood instructions
679 /// after (searching just for defs) \p Before.
681 /// \p Reg must be a physical register.
682 LivenessQueryResult computeRegisterLiveness(const TargetRegisterInfo *TRI,
684 const_iterator Before,
685 unsigned Neighborhood=10) const;
687 // Debugging methods.
689 void print(raw_ostream &OS, const SlotIndexes* = nullptr) const;
690 void print(raw_ostream &OS, ModuleSlotTracker &MST,
691 const SlotIndexes* = nullptr) const;
693 // Printing method used by LoopInfo.
694 void printAsOperand(raw_ostream &OS, bool PrintType = true) const;
696 /// MachineBasicBlocks are uniquely numbered at the function level, unless
697 /// they're not in a MachineFunction yet, in which case this will return -1.
698 int getNumber() const { return Number; }
699 void setNumber(int N) { Number = N; }
701 /// Return the MCSymbol for this basic block.
702 MCSymbol *getSymbol() const;
706 /// Return probability iterator corresponding to the I successor iterator.
707 probability_iterator getProbabilityIterator(succ_iterator I);
708 const_probability_iterator
709 getProbabilityIterator(const_succ_iterator I) const;
711 friend class MachineBranchProbabilityInfo;
712 friend class MIPrinter;
714 /// Return probability of the edge from this block to MBB. This method should
715 /// NOT be called directly, but by using getEdgeProbability method from
716 /// MachineBranchProbabilityInfo class.
717 BranchProbability getSuccProbability(const_succ_iterator Succ) const;
719 // Methods used to maintain doubly linked list of blocks...
720 friend struct ilist_callback_traits<MachineBasicBlock>;
722 // Machine-CFG mutators
724 /// Remove Pred as a predecessor of this MachineBasicBlock. Don't do this
725 /// unless you know what you're doing, because it doesn't update Pred's
726 /// successors list. Use Pred->addSuccessor instead.
727 void addPredecessor(MachineBasicBlock *Pred);
729 /// Remove Pred as a predecessor of this MachineBasicBlock. Don't do this
730 /// unless you know what you're doing, because it doesn't update Pred's
731 /// successors list. Use Pred->removeSuccessor instead.
732 void removePredecessor(MachineBasicBlock *Pred);
735 raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB);
737 // This is useful when building IndexedMaps keyed on basic block pointers.
738 struct MBB2NumberFunctor :
739 public std::unary_function<const MachineBasicBlock*, unsigned> {
740 unsigned operator()(const MachineBasicBlock *MBB) const {
741 return MBB->getNumber();
745 //===--------------------------------------------------------------------===//
746 // GraphTraits specializations for machine basic block graphs (machine-CFGs)
747 //===--------------------------------------------------------------------===//
749 // Provide specializations of GraphTraits to be able to treat a
750 // MachineFunction as a graph of MachineBasicBlocks.
753 template <> struct GraphTraits<MachineBasicBlock *> {
754 typedef MachineBasicBlock *NodeRef;
755 typedef MachineBasicBlock::succ_iterator ChildIteratorType;
757 static NodeRef getEntryNode(MachineBasicBlock *BB) { return BB; }
758 static ChildIteratorType child_begin(NodeRef N) { return N->succ_begin(); }
759 static ChildIteratorType child_end(NodeRef N) { return N->succ_end(); }
762 template <> struct GraphTraits<const MachineBasicBlock *> {
763 typedef const MachineBasicBlock *NodeRef;
764 typedef MachineBasicBlock::const_succ_iterator ChildIteratorType;
766 static NodeRef getEntryNode(const MachineBasicBlock *BB) { return BB; }
767 static ChildIteratorType child_begin(NodeRef N) { return N->succ_begin(); }
768 static ChildIteratorType child_end(NodeRef N) { return N->succ_end(); }
771 // Provide specializations of GraphTraits to be able to treat a
772 // MachineFunction as a graph of MachineBasicBlocks and to walk it
773 // in inverse order. Inverse order for a function is considered
774 // to be when traversing the predecessor edges of a MBB
775 // instead of the successor edges.
777 template <> struct GraphTraits<Inverse<MachineBasicBlock*> > {
778 typedef MachineBasicBlock *NodeRef;
779 typedef MachineBasicBlock::pred_iterator ChildIteratorType;
780 static NodeRef getEntryNode(Inverse<MachineBasicBlock *> G) {
783 static ChildIteratorType child_begin(NodeRef N) { return N->pred_begin(); }
784 static ChildIteratorType child_end(NodeRef N) { return N->pred_end(); }
787 template <> struct GraphTraits<Inverse<const MachineBasicBlock*> > {
788 typedef const MachineBasicBlock *NodeRef;
789 typedef MachineBasicBlock::const_pred_iterator ChildIteratorType;
790 static NodeRef getEntryNode(Inverse<const MachineBasicBlock *> G) {
793 static ChildIteratorType child_begin(NodeRef N) { return N->pred_begin(); }
794 static ChildIteratorType child_end(NodeRef N) { return N->pred_end(); }
799 /// MachineInstrSpan provides an interface to get an iteration range
800 /// containing the instruction it was initialized with, along with all
801 /// those instructions inserted prior to or following that instruction
802 /// at some point after the MachineInstrSpan is constructed.
803 class MachineInstrSpan {
804 MachineBasicBlock &MBB;
805 MachineBasicBlock::iterator I, B, E;
807 MachineInstrSpan(MachineBasicBlock::iterator I)
808 : MBB(*I->getParent()),
810 B(I == MBB.begin() ? MBB.end() : std::prev(I)),
813 MachineBasicBlock::iterator begin() {
814 return B == MBB.end() ? MBB.begin() : std::next(B);
816 MachineBasicBlock::iterator end() { return E; }
817 bool empty() { return begin() == end(); }
819 MachineBasicBlock::iterator getInitial() { return I; }
822 /// Increment \p It until it points to a non-debug instruction or to \p End
823 /// and return the resulting iterator. This function should only be used
824 /// MachineBasicBlock::{iterator, const_iterator, instr_iterator,
825 /// const_instr_iterator} and the respective reverse iterators.
826 template<typename IterT>
827 inline IterT skipDebugInstructionsForward(IterT It, IterT End) {
828 while (It != End && It->isDebugValue())
833 /// Decrement \p It until it points to a non-debug instruction or to \p Begin
834 /// and return the resulting iterator. This function should only be used
835 /// MachineBasicBlock::{iterator, const_iterator, instr_iterator,
836 /// const_instr_iterator} and the respective reverse iterators.
837 template<class IterT>
838 inline IterT skipDebugInstructionsBackward(IterT It, IterT Begin) {
839 while (It != Begin && It->isDebugValue())
844 } // End llvm namespace