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/ilist.h"
19 #include "llvm/ADT/ilist_node.h"
20 #include "llvm/ADT/iterator_range.h"
21 #include "llvm/ADT/simple_ilist.h"
22 #include "llvm/CodeGen/MachineInstr.h"
23 #include "llvm/CodeGen/MachineInstrBundleIterator.h"
24 #include "llvm/IR/DebugLoc.h"
25 #include "llvm/MC/LaneBitmask.h"
26 #include "llvm/MC/MCRegisterInfo.h"
27 #include "llvm/Support/BranchProbability.h"
28 #include "llvm/Support/Printable.h"
39 class MachineFunction;
41 class ModuleSlotTracker;
46 class TargetRegisterClass;
47 class TargetRegisterInfo;
49 template <> struct ilist_traits<MachineInstr> {
51 friend class MachineBasicBlock; // Set by the owning MachineBasicBlock.
53 MachineBasicBlock *Parent;
55 using instr_iterator =
56 simple_ilist<MachineInstr, ilist_sentinel_tracking<true>>::iterator;
59 void addNodeToList(MachineInstr *N);
60 void removeNodeFromList(MachineInstr *N);
61 void transferNodesFromList(ilist_traits &FromList, instr_iterator First,
63 void deleteNode(MachineInstr *MI);
66 class MachineBasicBlock
67 : public ilist_node_with_parent<MachineBasicBlock, MachineFunction> {
69 /// Pair of physical register and lane mask.
70 /// This is not simply a std::pair typedef because the members should be named
71 /// clearly as they both have an integer type.
72 struct RegisterMaskPair {
77 RegisterMaskPair(MCPhysReg PhysReg, LaneBitmask LaneMask)
78 : PhysReg(PhysReg), LaneMask(LaneMask) {}
82 using Instructions = ilist<MachineInstr, ilist_sentinel_tracking<true>>;
87 MachineFunction *xParent;
89 /// Keep track of the predecessor / successor basic blocks.
90 std::vector<MachineBasicBlock *> Predecessors;
91 std::vector<MachineBasicBlock *> Successors;
93 /// Keep track of the probabilities to the successors. This vector has the
94 /// same order as Successors, or it is empty if we don't use it (disable
96 std::vector<BranchProbability> Probs;
97 using probability_iterator = std::vector<BranchProbability>::iterator;
98 using const_probability_iterator =
99 std::vector<BranchProbability>::const_iterator;
101 Optional<uint64_t> IrrLoopHeaderWeight;
103 /// Keep track of the physical registers that are livein of the basicblock.
104 using LiveInVector = std::vector<RegisterMaskPair>;
105 LiveInVector LiveIns;
107 /// Alignment of the basic block. Zero if the basic block does not need to be
108 /// aligned. The alignment is specified as log2(bytes).
109 unsigned Alignment = 0;
111 /// Indicate that this basic block is entered via an exception handler.
112 bool IsEHPad = false;
114 /// Indicate that this basic block is potentially the target of an indirect
116 bool AddressTaken = false;
118 /// Indicate that this basic block is the entry block of an EH scope, i.e.,
119 /// the block that used to have a catchpad or cleanuppad instruction in the
121 bool IsEHScopeEntry = false;
123 /// Indicate that this basic block is the entry block of an EH funclet.
124 bool IsEHFuncletEntry = false;
126 /// Indicate that this basic block is the entry block of a cleanup funclet.
127 bool IsCleanupFuncletEntry = false;
129 /// since getSymbol is a relatively heavy-weight operation, the symbol
130 /// is only computed once and is cached.
131 mutable MCSymbol *CachedMCSymbol = nullptr;
133 // Intrusive list support
134 MachineBasicBlock() = default;
136 explicit MachineBasicBlock(MachineFunction &MF, const BasicBlock *BB);
138 ~MachineBasicBlock();
140 // MachineBasicBlocks are allocated and owned by MachineFunction.
141 friend class MachineFunction;
144 /// Return the LLVM basic block that this instance corresponded to originally.
145 /// Note that this may be NULL if this instance does not correspond directly
146 /// to an LLVM basic block.
147 const BasicBlock *getBasicBlock() const { return BB; }
149 /// Return the name of the corresponding LLVM basic block, or an empty string.
150 StringRef getName() const;
152 /// Return a formatted string to identify this block and its parent function.
153 std::string getFullName() const;
155 /// Test whether this block is potentially the target of an indirect branch.
156 bool hasAddressTaken() const { return AddressTaken; }
158 /// Set this block to reflect that it potentially is the target of an indirect
160 void setHasAddressTaken() { AddressTaken = true; }
162 /// Return the MachineFunction containing this basic block.
163 const MachineFunction *getParent() const { return xParent; }
164 MachineFunction *getParent() { return xParent; }
166 using instr_iterator = Instructions::iterator;
167 using const_instr_iterator = Instructions::const_iterator;
168 using reverse_instr_iterator = Instructions::reverse_iterator;
169 using const_reverse_instr_iterator = Instructions::const_reverse_iterator;
171 using iterator = MachineInstrBundleIterator<MachineInstr>;
172 using const_iterator = MachineInstrBundleIterator<const MachineInstr>;
173 using reverse_iterator = MachineInstrBundleIterator<MachineInstr, true>;
174 using const_reverse_iterator =
175 MachineInstrBundleIterator<const MachineInstr, true>;
177 unsigned size() const { return (unsigned)Insts.size(); }
178 bool empty() const { return Insts.empty(); }
180 MachineInstr &instr_front() { return Insts.front(); }
181 MachineInstr &instr_back() { return Insts.back(); }
182 const MachineInstr &instr_front() const { return Insts.front(); }
183 const MachineInstr &instr_back() const { return Insts.back(); }
185 MachineInstr &front() { return Insts.front(); }
186 MachineInstr &back() { return *--end(); }
187 const MachineInstr &front() const { return Insts.front(); }
188 const MachineInstr &back() const { return *--end(); }
190 instr_iterator instr_begin() { return Insts.begin(); }
191 const_instr_iterator instr_begin() const { return Insts.begin(); }
192 instr_iterator instr_end() { return Insts.end(); }
193 const_instr_iterator instr_end() const { return Insts.end(); }
194 reverse_instr_iterator instr_rbegin() { return Insts.rbegin(); }
195 const_reverse_instr_iterator instr_rbegin() const { return Insts.rbegin(); }
196 reverse_instr_iterator instr_rend () { return Insts.rend(); }
197 const_reverse_instr_iterator instr_rend () const { return Insts.rend(); }
199 using instr_range = iterator_range<instr_iterator>;
200 using const_instr_range = iterator_range<const_instr_iterator>;
201 instr_range instrs() { return instr_range(instr_begin(), instr_end()); }
202 const_instr_range instrs() const {
203 return const_instr_range(instr_begin(), instr_end());
206 iterator begin() { return instr_begin(); }
207 const_iterator begin() const { return instr_begin(); }
208 iterator end () { return instr_end(); }
209 const_iterator end () const { return instr_end(); }
210 reverse_iterator rbegin() {
211 return reverse_iterator::getAtBundleBegin(instr_rbegin());
213 const_reverse_iterator rbegin() const {
214 return const_reverse_iterator::getAtBundleBegin(instr_rbegin());
216 reverse_iterator rend() { return reverse_iterator(instr_rend()); }
217 const_reverse_iterator rend() const {
218 return const_reverse_iterator(instr_rend());
221 /// Support for MachineInstr::getNextNode().
222 static Instructions MachineBasicBlock::*getSublistAccess(MachineInstr *) {
223 return &MachineBasicBlock::Insts;
226 inline iterator_range<iterator> terminators() {
227 return make_range(getFirstTerminator(), end());
229 inline iterator_range<const_iterator> terminators() const {
230 return make_range(getFirstTerminator(), end());
233 /// Returns a range that iterates over the phis in the basic block.
234 inline iterator_range<iterator> phis() {
235 return make_range(begin(), getFirstNonPHI());
237 inline iterator_range<const_iterator> phis() const {
238 return const_cast<MachineBasicBlock *>(this)->phis();
241 // Machine-CFG iterators
242 using pred_iterator = std::vector<MachineBasicBlock *>::iterator;
243 using const_pred_iterator = std::vector<MachineBasicBlock *>::const_iterator;
244 using succ_iterator = std::vector<MachineBasicBlock *>::iterator;
245 using const_succ_iterator = std::vector<MachineBasicBlock *>::const_iterator;
246 using pred_reverse_iterator =
247 std::vector<MachineBasicBlock *>::reverse_iterator;
248 using const_pred_reverse_iterator =
249 std::vector<MachineBasicBlock *>::const_reverse_iterator;
250 using succ_reverse_iterator =
251 std::vector<MachineBasicBlock *>::reverse_iterator;
252 using const_succ_reverse_iterator =
253 std::vector<MachineBasicBlock *>::const_reverse_iterator;
254 pred_iterator pred_begin() { return Predecessors.begin(); }
255 const_pred_iterator pred_begin() const { return Predecessors.begin(); }
256 pred_iterator pred_end() { return Predecessors.end(); }
257 const_pred_iterator pred_end() const { return Predecessors.end(); }
258 pred_reverse_iterator pred_rbegin()
259 { return Predecessors.rbegin();}
260 const_pred_reverse_iterator pred_rbegin() const
261 { return Predecessors.rbegin();}
262 pred_reverse_iterator pred_rend()
263 { return Predecessors.rend(); }
264 const_pred_reverse_iterator pred_rend() const
265 { return Predecessors.rend(); }
266 unsigned pred_size() const {
267 return (unsigned)Predecessors.size();
269 bool pred_empty() const { return Predecessors.empty(); }
270 succ_iterator succ_begin() { return Successors.begin(); }
271 const_succ_iterator succ_begin() const { return Successors.begin(); }
272 succ_iterator succ_end() { return Successors.end(); }
273 const_succ_iterator succ_end() const { return Successors.end(); }
274 succ_reverse_iterator succ_rbegin()
275 { return Successors.rbegin(); }
276 const_succ_reverse_iterator succ_rbegin() const
277 { return Successors.rbegin(); }
278 succ_reverse_iterator succ_rend()
279 { return Successors.rend(); }
280 const_succ_reverse_iterator succ_rend() const
281 { return Successors.rend(); }
282 unsigned succ_size() const {
283 return (unsigned)Successors.size();
285 bool succ_empty() const { return Successors.empty(); }
287 inline iterator_range<pred_iterator> predecessors() {
288 return make_range(pred_begin(), pred_end());
290 inline iterator_range<const_pred_iterator> predecessors() const {
291 return make_range(pred_begin(), pred_end());
293 inline iterator_range<succ_iterator> successors() {
294 return make_range(succ_begin(), succ_end());
296 inline iterator_range<const_succ_iterator> successors() const {
297 return make_range(succ_begin(), succ_end());
300 // LiveIn management methods.
302 /// Adds the specified register as a live in. Note that it is an error to add
303 /// the same register to the same set more than once unless the intention is
304 /// to call sortUniqueLiveIns after all registers are added.
305 void addLiveIn(MCPhysReg PhysReg,
306 LaneBitmask LaneMask = LaneBitmask::getAll()) {
307 LiveIns.push_back(RegisterMaskPair(PhysReg, LaneMask));
309 void addLiveIn(const RegisterMaskPair &RegMaskPair) {
310 LiveIns.push_back(RegMaskPair);
313 /// Sorts and uniques the LiveIns vector. It can be significantly faster to do
314 /// this than repeatedly calling isLiveIn before calling addLiveIn for every
315 /// LiveIn insertion.
316 void sortUniqueLiveIns();
318 /// Clear live in list.
321 /// Add PhysReg as live in to this block, and ensure that there is a copy of
322 /// PhysReg to a virtual register of class RC. Return the virtual register
323 /// that is a copy of the live in PhysReg.
324 unsigned addLiveIn(MCPhysReg PhysReg, const TargetRegisterClass *RC);
326 /// Remove the specified register from the live in set.
327 void removeLiveIn(MCPhysReg Reg,
328 LaneBitmask LaneMask = LaneBitmask::getAll());
330 /// Return true if the specified register is in the live in set.
331 bool isLiveIn(MCPhysReg Reg,
332 LaneBitmask LaneMask = LaneBitmask::getAll()) const;
334 // Iteration support for live in sets. These sets are kept in sorted
335 // order by their register number.
336 using livein_iterator = LiveInVector::const_iterator;
338 /// Unlike livein_begin, this method does not check that the liveness
339 /// information is accurate. Still for debug purposes it may be useful
340 /// to have iterators that won't assert if the liveness information
342 livein_iterator livein_begin_dbg() const { return LiveIns.begin(); }
343 iterator_range<livein_iterator> liveins_dbg() const {
344 return make_range(livein_begin_dbg(), livein_end());
347 livein_iterator livein_begin() const;
348 livein_iterator livein_end() const { return LiveIns.end(); }
349 bool livein_empty() const { return LiveIns.empty(); }
350 iterator_range<livein_iterator> liveins() const {
351 return make_range(livein_begin(), livein_end());
354 /// Remove entry from the livein set and return iterator to the next.
355 livein_iterator removeLiveIn(livein_iterator I);
357 /// Get the clobber mask for the start of this basic block. Funclets use this
358 /// to prevent register allocation across funclet transitions.
359 const uint32_t *getBeginClobberMask(const TargetRegisterInfo *TRI) const;
361 /// Get the clobber mask for the end of the basic block.
362 /// \see getBeginClobberMask()
363 const uint32_t *getEndClobberMask(const TargetRegisterInfo *TRI) const;
365 /// Return alignment of the basic block. The alignment is specified as
367 unsigned getAlignment() const { return Alignment; }
369 /// Set alignment of the basic block. The alignment is specified as
371 void setAlignment(unsigned Align) { Alignment = Align; }
373 /// Returns true if the block is a landing pad. That is this basic block is
374 /// entered via an exception handler.
375 bool isEHPad() const { return IsEHPad; }
377 /// Indicates the block is a landing pad. That is this basic block is entered
378 /// via an exception handler.
379 void setIsEHPad(bool V = true) { IsEHPad = V; }
381 bool hasEHPadSuccessor() const;
383 /// Returns true if this is the entry block of an EH scope, i.e., the block
384 /// that used to have a catchpad or cleanuppad instruction in the LLVM IR.
385 bool isEHScopeEntry() const { return IsEHScopeEntry; }
387 /// Indicates if this is the entry block of an EH scope, i.e., the block that
388 /// that used to have a catchpad or cleanuppad instruction in the LLVM IR.
389 void setIsEHScopeEntry(bool V = true) { IsEHScopeEntry = V; }
391 /// Returns true if this is the entry block of an EH funclet.
392 bool isEHFuncletEntry() const { return IsEHFuncletEntry; }
394 /// Indicates if this is the entry block of an EH funclet.
395 void setIsEHFuncletEntry(bool V = true) { IsEHFuncletEntry = V; }
397 /// Returns true if this is the entry block of a cleanup funclet.
398 bool isCleanupFuncletEntry() const { return IsCleanupFuncletEntry; }
400 /// Indicates if this is the entry block of a cleanup funclet.
401 void setIsCleanupFuncletEntry(bool V = true) { IsCleanupFuncletEntry = V; }
403 /// Returns true if it is legal to hoist instructions into this block.
404 bool isLegalToHoistInto() const;
406 // Code Layout methods.
408 /// Move 'this' block before or after the specified block. This only moves
409 /// the block, it does not modify the CFG or adjust potential fall-throughs at
410 /// the end of the block.
411 void moveBefore(MachineBasicBlock *NewAfter);
412 void moveAfter(MachineBasicBlock *NewBefore);
414 /// Update the terminator instructions in block to account for changes to the
415 /// layout. If the block previously used a fallthrough, it may now need a
416 /// branch, and if it previously used branching it may now be able to use a
418 void updateTerminator();
420 // Machine-CFG mutators
422 /// Add Succ as a successor of this MachineBasicBlock. The Predecessors list
423 /// of Succ is automatically updated. PROB parameter is stored in
424 /// Probabilities list. The default probability is set as unknown. Mixing
425 /// known and unknown probabilities in successor list is not allowed. When all
426 /// successors have unknown probabilities, 1 / N is returned as the
427 /// probability for each successor, where N is the number of successors.
429 /// Note that duplicate Machine CFG edges are not allowed.
430 void addSuccessor(MachineBasicBlock *Succ,
431 BranchProbability Prob = BranchProbability::getUnknown());
433 /// Add Succ as a successor of this MachineBasicBlock. The Predecessors list
434 /// of Succ is automatically updated. The probability is not provided because
435 /// BPI is not available (e.g. -O0 is used), in which case edge probabilities
436 /// won't be used. Using this interface can save some space.
437 void addSuccessorWithoutProb(MachineBasicBlock *Succ);
439 /// Set successor probability of a given iterator.
440 void setSuccProbability(succ_iterator I, BranchProbability Prob);
442 /// Normalize probabilities of all successors so that the sum of them becomes
443 /// one. This is usually done when the current update on this MBB is done, and
444 /// the sum of its successors' probabilities is not guaranteed to be one. The
445 /// user is responsible for the correct use of this function.
446 /// MBB::removeSuccessor() has an option to do this automatically.
447 void normalizeSuccProbs() {
448 BranchProbability::normalizeProbabilities(Probs.begin(), Probs.end());
451 /// Validate successors' probabilities and check if the sum of them is
452 /// approximate one. This only works in DEBUG mode.
453 void validateSuccProbs() const;
455 /// Remove successor from the successors list of this MachineBasicBlock. The
456 /// Predecessors list of Succ is automatically updated.
457 /// If NormalizeSuccProbs is true, then normalize successors' probabilities
458 /// after the successor is removed.
459 void removeSuccessor(MachineBasicBlock *Succ,
460 bool NormalizeSuccProbs = false);
462 /// Remove specified successor from the successors list of this
463 /// MachineBasicBlock. The Predecessors list of Succ is automatically updated.
464 /// If NormalizeSuccProbs is true, then normalize successors' probabilities
465 /// after the successor is removed.
466 /// Return the iterator to the element after the one removed.
467 succ_iterator removeSuccessor(succ_iterator I,
468 bool NormalizeSuccProbs = false);
470 /// Replace successor OLD with NEW and update probability info.
471 void replaceSuccessor(MachineBasicBlock *Old, MachineBasicBlock *New);
473 /// Copy a successor (and any probability info) from original block to this
474 /// block's. Uses an iterator into the original blocks successors.
476 /// This is useful when doing a partial clone of successors. Afterward, the
477 /// probabilities may need to be normalized.
478 void copySuccessor(MachineBasicBlock *Orig, succ_iterator I);
480 /// Split the old successor into old plus new and updates the probability
482 void splitSuccessor(MachineBasicBlock *Old, MachineBasicBlock *New,
483 bool NormalizeSuccProbs = false);
485 /// Transfers all the successors from MBB to this machine basic block (i.e.,
486 /// copies all the successors FromMBB and remove all the successors from
488 void transferSuccessors(MachineBasicBlock *FromMBB);
490 /// Transfers all the successors, as in transferSuccessors, and update PHI
491 /// operands in the successor blocks which refer to FromMBB to refer to this.
492 void transferSuccessorsAndUpdatePHIs(MachineBasicBlock *FromMBB);
494 /// Return true if any of the successors have probabilities attached to them.
495 bool hasSuccessorProbabilities() const { return !Probs.empty(); }
497 /// Return true if the specified MBB is a predecessor of this block.
498 bool isPredecessor(const MachineBasicBlock *MBB) const;
500 /// Return true if the specified MBB is a successor of this block.
501 bool isSuccessor(const MachineBasicBlock *MBB) const;
503 /// Return true if the specified MBB will be emitted immediately after this
504 /// block, such that if this block exits by falling through, control will
505 /// transfer to the specified MBB. Note that MBB need not be a successor at
506 /// all, for example if this block ends with an unconditional branch to some
508 bool isLayoutSuccessor(const MachineBasicBlock *MBB) const;
510 /// Return the fallthrough block if the block can implicitly
511 /// transfer control to the block after it by falling off the end of
512 /// it. This should return null if it can reach the block after
513 /// it, but it uses an explicit branch to do so (e.g., a table
514 /// jump). Non-null return is a conservative answer.
515 MachineBasicBlock *getFallThrough();
517 /// Return true if the block can implicitly transfer control to the
518 /// block after it by falling off the end of it. This should return
519 /// false if it can reach the block after it, but it uses an
520 /// explicit branch to do so (e.g., a table jump). True is a
521 /// conservative answer.
522 bool canFallThrough();
524 /// Returns a pointer to the first instruction in this block that is not a
525 /// PHINode instruction. When adding instructions to the beginning of the
526 /// basic block, they should be added before the returned value, not before
527 /// the first instruction, which might be PHI.
528 /// Returns end() is there's no non-PHI instruction.
529 iterator getFirstNonPHI();
531 /// Return the first instruction in MBB after I that is not a PHI or a label.
532 /// This is the correct point to insert lowered copies at the beginning of a
533 /// basic block that must be before any debugging information.
534 iterator SkipPHIsAndLabels(iterator I);
536 /// Return the first instruction in MBB after I that is not a PHI, label or
537 /// debug. This is the correct point to insert copies at the beginning of a
539 iterator SkipPHIsLabelsAndDebug(iterator I);
541 /// Returns an iterator to the first terminator instruction of this basic
542 /// block. If a terminator does not exist, it returns end().
543 iterator getFirstTerminator();
544 const_iterator getFirstTerminator() const {
545 return const_cast<MachineBasicBlock *>(this)->getFirstTerminator();
548 /// Same getFirstTerminator but it ignores bundles and return an
549 /// instr_iterator instead.
550 instr_iterator getFirstInstrTerminator();
552 /// Returns an iterator to the first non-debug instruction in the basic block,
554 iterator getFirstNonDebugInstr();
555 const_iterator getFirstNonDebugInstr() const {
556 return const_cast<MachineBasicBlock *>(this)->getFirstNonDebugInstr();
559 /// Returns an iterator to the last non-debug instruction in the basic block,
561 iterator getLastNonDebugInstr();
562 const_iterator getLastNonDebugInstr() const {
563 return const_cast<MachineBasicBlock *>(this)->getLastNonDebugInstr();
566 /// Convenience function that returns true if the block ends in a return
568 bool isReturnBlock() const {
569 return !empty() && back().isReturn();
572 /// Split the critical edge from this block to the given successor block, and
573 /// return the newly created block, or null if splitting is not possible.
575 /// This function updates LiveVariables, MachineDominatorTree, and
576 /// MachineLoopInfo, as applicable.
577 MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *Succ, Pass &P);
579 /// Check if the edge between this block and the given successor \p
580 /// Succ, can be split. If this returns true a subsequent call to
581 /// SplitCriticalEdge is guaranteed to return a valid basic block if
582 /// no changes occurred in the meantime.
583 bool canSplitCriticalEdge(const MachineBasicBlock *Succ) const;
585 void pop_front() { Insts.pop_front(); }
586 void pop_back() { Insts.pop_back(); }
587 void push_back(MachineInstr *MI) { Insts.push_back(MI); }
589 /// Insert MI into the instruction list before I, possibly inside a bundle.
591 /// If the insertion point is inside a bundle, MI will be added to the bundle,
592 /// otherwise MI will not be added to any bundle. That means this function
593 /// alone can't be used to prepend or append instructions to bundles. See
594 /// MIBundleBuilder::insert() for a more reliable way of doing that.
595 instr_iterator insert(instr_iterator I, MachineInstr *M);
597 /// Insert a range of instructions into the instruction list before I.
598 template<typename IT>
599 void insert(iterator I, IT S, IT E) {
600 assert((I == end() || I->getParent() == this) &&
601 "iterator points outside of basic block");
602 Insts.insert(I.getInstrIterator(), S, E);
605 /// Insert MI into the instruction list before I.
606 iterator insert(iterator I, MachineInstr *MI) {
607 assert((I == end() || I->getParent() == this) &&
608 "iterator points outside of basic block");
609 assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
610 "Cannot insert instruction with bundle flags");
611 return Insts.insert(I.getInstrIterator(), MI);
614 /// Insert MI into the instruction list after I.
615 iterator insertAfter(iterator I, MachineInstr *MI) {
616 assert((I == end() || I->getParent() == this) &&
617 "iterator points outside of basic block");
618 assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
619 "Cannot insert instruction with bundle flags");
620 return Insts.insertAfter(I.getInstrIterator(), MI);
623 /// Remove an instruction from the instruction list and delete it.
625 /// If the instruction is part of a bundle, the other instructions in the
626 /// bundle will still be bundled after removing the single instruction.
627 instr_iterator erase(instr_iterator I);
629 /// Remove an instruction from the instruction list and delete it.
631 /// If the instruction is part of a bundle, the other instructions in the
632 /// bundle will still be bundled after removing the single instruction.
633 instr_iterator erase_instr(MachineInstr *I) {
634 return erase(instr_iterator(I));
637 /// Remove a range of instructions from the instruction list and delete them.
638 iterator erase(iterator I, iterator E) {
639 return Insts.erase(I.getInstrIterator(), E.getInstrIterator());
642 /// Remove an instruction or bundle from the instruction list and delete it.
644 /// If I points to a bundle of instructions, they are all erased.
645 iterator erase(iterator I) {
646 return erase(I, std::next(I));
649 /// Remove an instruction from the instruction list and delete it.
651 /// If I is the head of a bundle of instructions, the whole bundle will be
653 iterator erase(MachineInstr *I) {
654 return erase(iterator(I));
657 /// Remove the unbundled instruction from the instruction list without
660 /// This function can not be used to remove bundled instructions, use
661 /// remove_instr to remove individual instructions from a bundle.
662 MachineInstr *remove(MachineInstr *I) {
663 assert(!I->isBundled() && "Cannot remove bundled instructions");
664 return Insts.remove(instr_iterator(I));
667 /// Remove the possibly bundled instruction from the instruction list
668 /// without deleting it.
670 /// If the instruction is part of a bundle, the other instructions in the
671 /// bundle will still be bundled after removing the single instruction.
672 MachineInstr *remove_instr(MachineInstr *I);
678 /// Take an instruction from MBB 'Other' at the position From, and insert it
679 /// into this MBB right before 'Where'.
681 /// If From points to a bundle of instructions, the whole bundle is moved.
682 void splice(iterator Where, MachineBasicBlock *Other, iterator From) {
683 // The range splice() doesn't allow noop moves, but this one does.
685 splice(Where, Other, From, std::next(From));
688 /// Take a block of instructions from MBB 'Other' in the range [From, To),
689 /// and insert them into this MBB right before 'Where'.
691 /// The instruction at 'Where' must not be included in the range of
692 /// instructions to move.
693 void splice(iterator Where, MachineBasicBlock *Other,
694 iterator From, iterator To) {
695 Insts.splice(Where.getInstrIterator(), Other->Insts,
696 From.getInstrIterator(), To.getInstrIterator());
699 /// This method unlinks 'this' from the containing function, and returns it,
700 /// but does not delete it.
701 MachineBasicBlock *removeFromParent();
703 /// This method unlinks 'this' from the containing function and deletes it.
704 void eraseFromParent();
706 /// Given a machine basic block that branched to 'Old', change the code and
707 /// CFG so that it branches to 'New' instead.
708 void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New);
710 /// Various pieces of code can cause excess edges in the CFG to be inserted.
711 /// If we have proven that MBB can only branch to DestA and DestB, remove any
712 /// other MBB successors from the CFG. DestA and DestB can be null. Besides
713 /// DestA and DestB, retain other edges leading to LandingPads (currently
714 /// there can be only one; we don't check or require that here). Note it is
715 /// possible that DestA and/or DestB are LandingPads.
716 bool CorrectExtraCFGEdges(MachineBasicBlock *DestA,
717 MachineBasicBlock *DestB,
720 /// Find the next valid DebugLoc starting at MBBI, skipping any DBG_VALUE
721 /// and DBG_LABEL instructions. Return UnknownLoc if there is none.
722 DebugLoc findDebugLoc(instr_iterator MBBI);
723 DebugLoc findDebugLoc(iterator MBBI) {
724 return findDebugLoc(MBBI.getInstrIterator());
727 /// Find the previous valid DebugLoc preceding MBBI, skipping and DBG_VALUE
728 /// instructions. Return UnknownLoc if there is none.
729 DebugLoc findPrevDebugLoc(instr_iterator MBBI);
730 DebugLoc findPrevDebugLoc(iterator MBBI) {
731 return findPrevDebugLoc(MBBI.getInstrIterator());
734 /// Find and return the merged DebugLoc of the branch instructions of the
735 /// block. Return UnknownLoc if there is none.
736 DebugLoc findBranchDebugLoc();
738 /// Possible outcome of a register liveness query to computeRegisterLiveness()
739 enum LivenessQueryResult {
740 LQR_Live, ///< Register is known to be (at least partially) live.
741 LQR_Dead, ///< Register is known to be fully dead.
742 LQR_Unknown ///< Register liveness not decidable from local neighborhood.
745 /// Return whether (physical) register \p Reg has been defined and not
746 /// killed as of just before \p Before.
748 /// Search is localised to a neighborhood of \p Neighborhood instructions
749 /// before (searching for defs or kills) and \p Neighborhood instructions
750 /// after (searching just for defs) \p Before.
752 /// \p Reg must be a physical register.
753 LivenessQueryResult computeRegisterLiveness(const TargetRegisterInfo *TRI,
755 const_iterator Before,
756 unsigned Neighborhood = 10) const;
758 // Debugging methods.
760 void print(raw_ostream &OS, const SlotIndexes * = nullptr,
761 bool IsStandalone = true) const;
762 void print(raw_ostream &OS, ModuleSlotTracker &MST,
763 const SlotIndexes * = nullptr, bool IsStandalone = true) const;
765 // Printing method used by LoopInfo.
766 void printAsOperand(raw_ostream &OS, bool PrintType = true) const;
768 /// MachineBasicBlocks are uniquely numbered at the function level, unless
769 /// they're not in a MachineFunction yet, in which case this will return -1.
770 int getNumber() const { return Number; }
771 void setNumber(int N) { Number = N; }
773 /// Return the MCSymbol for this basic block.
774 MCSymbol *getSymbol() const;
776 Optional<uint64_t> getIrrLoopHeaderWeight() const {
777 return IrrLoopHeaderWeight;
780 void setIrrLoopHeaderWeight(uint64_t Weight) {
781 IrrLoopHeaderWeight = Weight;
785 /// Return probability iterator corresponding to the I successor iterator.
786 probability_iterator getProbabilityIterator(succ_iterator I);
787 const_probability_iterator
788 getProbabilityIterator(const_succ_iterator I) const;
790 friend class MachineBranchProbabilityInfo;
791 friend class MIPrinter;
793 /// Return probability of the edge from this block to MBB. This method should
794 /// NOT be called directly, but by using getEdgeProbability method from
795 /// MachineBranchProbabilityInfo class.
796 BranchProbability getSuccProbability(const_succ_iterator Succ) const;
798 // Methods used to maintain doubly linked list of blocks...
799 friend struct ilist_callback_traits<MachineBasicBlock>;
801 // Machine-CFG mutators
803 /// Add Pred as a predecessor of this MachineBasicBlock. Don't do this
804 /// unless you know what you're doing, because it doesn't update Pred's
805 /// successors list. Use Pred->addSuccessor instead.
806 void addPredecessor(MachineBasicBlock *Pred);
808 /// Remove Pred as a predecessor of this MachineBasicBlock. Don't do this
809 /// unless you know what you're doing, because it doesn't update Pred's
810 /// successors list. Use Pred->removeSuccessor instead.
811 void removePredecessor(MachineBasicBlock *Pred);
814 raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB);
816 /// Prints a machine basic block reference.
819 /// %bb.5 - a machine basic block with MBB.getNumber() == 5.
821 /// Usage: OS << printMBBReference(MBB) << '\n';
822 Printable printMBBReference(const MachineBasicBlock &MBB);
824 // This is useful when building IndexedMaps keyed on basic block pointers.
825 struct MBB2NumberFunctor {
826 using argument_type = const MachineBasicBlock *;
827 unsigned operator()(const MachineBasicBlock *MBB) const {
828 return MBB->getNumber();
832 //===--------------------------------------------------------------------===//
833 // GraphTraits specializations for machine basic block graphs (machine-CFGs)
834 //===--------------------------------------------------------------------===//
836 // Provide specializations of GraphTraits to be able to treat a
837 // MachineFunction as a graph of MachineBasicBlocks.
840 template <> struct GraphTraits<MachineBasicBlock *> {
841 using NodeRef = MachineBasicBlock *;
842 using ChildIteratorType = MachineBasicBlock::succ_iterator;
844 static NodeRef getEntryNode(MachineBasicBlock *BB) { return BB; }
845 static ChildIteratorType child_begin(NodeRef N) { return N->succ_begin(); }
846 static ChildIteratorType child_end(NodeRef N) { return N->succ_end(); }
849 template <> struct GraphTraits<const MachineBasicBlock *> {
850 using NodeRef = const MachineBasicBlock *;
851 using ChildIteratorType = MachineBasicBlock::const_succ_iterator;
853 static NodeRef getEntryNode(const MachineBasicBlock *BB) { return BB; }
854 static ChildIteratorType child_begin(NodeRef N) { return N->succ_begin(); }
855 static ChildIteratorType child_end(NodeRef N) { return N->succ_end(); }
858 // Provide specializations of GraphTraits to be able to treat a
859 // MachineFunction as a graph of MachineBasicBlocks and to walk it
860 // in inverse order. Inverse order for a function is considered
861 // to be when traversing the predecessor edges of a MBB
862 // instead of the successor edges.
864 template <> struct GraphTraits<Inverse<MachineBasicBlock*>> {
865 using NodeRef = MachineBasicBlock *;
866 using ChildIteratorType = MachineBasicBlock::pred_iterator;
868 static NodeRef getEntryNode(Inverse<MachineBasicBlock *> G) {
872 static ChildIteratorType child_begin(NodeRef N) { return N->pred_begin(); }
873 static ChildIteratorType child_end(NodeRef N) { return N->pred_end(); }
876 template <> struct GraphTraits<Inverse<const MachineBasicBlock*>> {
877 using NodeRef = const MachineBasicBlock *;
878 using ChildIteratorType = MachineBasicBlock::const_pred_iterator;
880 static NodeRef getEntryNode(Inverse<const MachineBasicBlock *> G) {
884 static ChildIteratorType child_begin(NodeRef N) { return N->pred_begin(); }
885 static ChildIteratorType child_end(NodeRef N) { return N->pred_end(); }
888 /// MachineInstrSpan provides an interface to get an iteration range
889 /// containing the instruction it was initialized with, along with all
890 /// those instructions inserted prior to or following that instruction
891 /// at some point after the MachineInstrSpan is constructed.
892 class MachineInstrSpan {
893 MachineBasicBlock &MBB;
894 MachineBasicBlock::iterator I, B, E;
897 MachineInstrSpan(MachineBasicBlock::iterator I)
898 : MBB(*I->getParent()),
900 B(I == MBB.begin() ? MBB.end() : std::prev(I)),
903 MachineBasicBlock::iterator begin() {
904 return B == MBB.end() ? MBB.begin() : std::next(B);
906 MachineBasicBlock::iterator end() { return E; }
907 bool empty() { return begin() == end(); }
909 MachineBasicBlock::iterator getInitial() { return I; }
912 /// Increment \p It until it points to a non-debug instruction or to \p End
913 /// and return the resulting iterator. This function should only be used
914 /// MachineBasicBlock::{iterator, const_iterator, instr_iterator,
915 /// const_instr_iterator} and the respective reverse iterators.
916 template<typename IterT>
917 inline IterT skipDebugInstructionsForward(IterT It, IterT End) {
918 while (It != End && It->isDebugInstr())
923 /// Decrement \p It until it points to a non-debug instruction or to \p Begin
924 /// and return the resulting iterator. This function should only be used
925 /// MachineBasicBlock::{iterator, const_iterator, instr_iterator,
926 /// const_instr_iterator} and the respective reverse iterators.
927 template<class IterT>
928 inline IterT skipDebugInstructionsBackward(IterT It, IterT Begin) {
929 while (It != Begin && It->isDebugInstr())
934 } // end namespace llvm
936 #endif // LLVM_CODEGEN_MACHINEBASICBLOCK_H