[Alignment][NFC] Migrate Instructions to Align
[llvm-core.git] / include / llvm / CodeGen / MachineBasicBlock.h
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1 //===- llvm/CodeGen/MachineBasicBlock.h -------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // Collect the sequence of machine instructions for a basic block.
11 //===----------------------------------------------------------------------===//
13 #ifndef LLVM_CODEGEN_MACHINEBASICBLOCK_H
14 #define LLVM_CODEGEN_MACHINEBASICBLOCK_H
16 #include "llvm/ADT/GraphTraits.h"
17 #include "llvm/ADT/ilist.h"
18 #include "llvm/ADT/ilist_node.h"
19 #include "llvm/ADT/iterator_range.h"
20 #include "llvm/ADT/simple_ilist.h"
21 #include "llvm/CodeGen/MachineInstr.h"
22 #include "llvm/CodeGen/MachineInstrBundleIterator.h"
23 #include "llvm/IR/DebugLoc.h"
24 #include "llvm/MC/LaneBitmask.h"
25 #include "llvm/MC/MCRegisterInfo.h"
26 #include "llvm/Support/BranchProbability.h"
27 #include "llvm/Support/Printable.h"
28 #include <cassert>
29 #include <cstdint>
30 #include <functional>
31 #include <iterator>
32 #include <string>
33 #include <vector>
35 namespace llvm {
37 class BasicBlock;
38 class MachineFunction;
39 class MCSymbol;
40 class ModuleSlotTracker;
41 class Pass;
42 class SlotIndexes;
43 class StringRef;
44 class raw_ostream;
45 class TargetRegisterClass;
46 class TargetRegisterInfo;
48 template <> struct ilist_traits<MachineInstr> {
49 private:
50 friend class MachineBasicBlock; // Set by the owning MachineBasicBlock.
52 MachineBasicBlock *Parent;
54 using instr_iterator =
55 simple_ilist<MachineInstr, ilist_sentinel_tracking<true>>::iterator;
57 public:
58 void addNodeToList(MachineInstr *N);
59 void removeNodeFromList(MachineInstr *N);
60 void transferNodesFromList(ilist_traits &FromList, instr_iterator First,
61 instr_iterator Last);
62 void deleteNode(MachineInstr *MI);
65 class MachineBasicBlock
66 : public ilist_node_with_parent<MachineBasicBlock, MachineFunction> {
67 public:
68 /// Pair of physical register and lane mask.
69 /// This is not simply a std::pair typedef because the members should be named
70 /// clearly as they both have an integer type.
71 struct RegisterMaskPair {
72 public:
73 MCPhysReg PhysReg;
74 LaneBitmask LaneMask;
76 RegisterMaskPair(MCPhysReg PhysReg, LaneBitmask LaneMask)
77 : PhysReg(PhysReg), LaneMask(LaneMask) {}
80 private:
81 using Instructions = ilist<MachineInstr, ilist_sentinel_tracking<true>>;
83 Instructions Insts;
84 const BasicBlock *BB;
85 int Number;
86 MachineFunction *xParent;
88 /// Keep track of the predecessor / successor basic blocks.
89 std::vector<MachineBasicBlock *> Predecessors;
90 std::vector<MachineBasicBlock *> Successors;
92 /// Keep track of the probabilities to the successors. This vector has the
93 /// same order as Successors, or it is empty if we don't use it (disable
94 /// optimization).
95 std::vector<BranchProbability> Probs;
96 using probability_iterator = std::vector<BranchProbability>::iterator;
97 using const_probability_iterator =
98 std::vector<BranchProbability>::const_iterator;
100 Optional<uint64_t> IrrLoopHeaderWeight;
102 /// Keep track of the physical registers that are livein of the basicblock.
103 using LiveInVector = std::vector<RegisterMaskPair>;
104 LiveInVector LiveIns;
106 /// Alignment of the basic block. One if the basic block does not need to be
107 /// aligned.
108 llvm::Align Alignment;
110 /// Indicate that this basic block is entered via an exception handler.
111 bool IsEHPad = false;
113 /// Indicate that this basic block is potentially the target of an indirect
114 /// branch.
115 bool AddressTaken = false;
117 /// Indicate that this basic block needs its symbol be emitted regardless of
118 /// whether the flow just falls-through to it.
119 bool LabelMustBeEmitted = false;
121 /// Indicate that this basic block is the entry block of an EH scope, i.e.,
122 /// the block that used to have a catchpad or cleanuppad instruction in the
123 /// LLVM IR.
124 bool IsEHScopeEntry = false;
126 /// Indicate that this basic block is the entry block of an EH funclet.
127 bool IsEHFuncletEntry = false;
129 /// Indicate that this basic block is the entry block of a cleanup funclet.
130 bool IsCleanupFuncletEntry = false;
132 /// since getSymbol is a relatively heavy-weight operation, the symbol
133 /// is only computed once and is cached.
134 mutable MCSymbol *CachedMCSymbol = nullptr;
136 // Intrusive list support
137 MachineBasicBlock() = default;
139 explicit MachineBasicBlock(MachineFunction &MF, const BasicBlock *BB);
141 ~MachineBasicBlock();
143 // MachineBasicBlocks are allocated and owned by MachineFunction.
144 friend class MachineFunction;
146 public:
147 /// Return the LLVM basic block that this instance corresponded to originally.
148 /// Note that this may be NULL if this instance does not correspond directly
149 /// to an LLVM basic block.
150 const BasicBlock *getBasicBlock() const { return BB; }
152 /// Return the name of the corresponding LLVM basic block, or an empty string.
153 StringRef getName() const;
155 /// Return a formatted string to identify this block and its parent function.
156 std::string getFullName() const;
158 /// Test whether this block is potentially the target of an indirect branch.
159 bool hasAddressTaken() const { return AddressTaken; }
161 /// Set this block to reflect that it potentially is the target of an indirect
162 /// branch.
163 void setHasAddressTaken() { AddressTaken = true; }
165 /// Test whether this block must have its label emitted.
166 bool hasLabelMustBeEmitted() const { return LabelMustBeEmitted; }
168 /// Set this block to reflect that, regardless how we flow to it, we need
169 /// its label be emitted.
170 void setLabelMustBeEmitted() { LabelMustBeEmitted = true; }
172 /// Return the MachineFunction containing this basic block.
173 const MachineFunction *getParent() const { return xParent; }
174 MachineFunction *getParent() { return xParent; }
176 using instr_iterator = Instructions::iterator;
177 using const_instr_iterator = Instructions::const_iterator;
178 using reverse_instr_iterator = Instructions::reverse_iterator;
179 using const_reverse_instr_iterator = Instructions::const_reverse_iterator;
181 using iterator = MachineInstrBundleIterator<MachineInstr>;
182 using const_iterator = MachineInstrBundleIterator<const MachineInstr>;
183 using reverse_iterator = MachineInstrBundleIterator<MachineInstr, true>;
184 using const_reverse_iterator =
185 MachineInstrBundleIterator<const MachineInstr, true>;
187 unsigned size() const { return (unsigned)Insts.size(); }
188 bool empty() const { return Insts.empty(); }
190 MachineInstr &instr_front() { return Insts.front(); }
191 MachineInstr &instr_back() { return Insts.back(); }
192 const MachineInstr &instr_front() const { return Insts.front(); }
193 const MachineInstr &instr_back() const { return Insts.back(); }
195 MachineInstr &front() { return Insts.front(); }
196 MachineInstr &back() { return *--end(); }
197 const MachineInstr &front() const { return Insts.front(); }
198 const MachineInstr &back() const { return *--end(); }
200 instr_iterator instr_begin() { return Insts.begin(); }
201 const_instr_iterator instr_begin() const { return Insts.begin(); }
202 instr_iterator instr_end() { return Insts.end(); }
203 const_instr_iterator instr_end() const { return Insts.end(); }
204 reverse_instr_iterator instr_rbegin() { return Insts.rbegin(); }
205 const_reverse_instr_iterator instr_rbegin() const { return Insts.rbegin(); }
206 reverse_instr_iterator instr_rend () { return Insts.rend(); }
207 const_reverse_instr_iterator instr_rend () const { return Insts.rend(); }
209 using instr_range = iterator_range<instr_iterator>;
210 using const_instr_range = iterator_range<const_instr_iterator>;
211 instr_range instrs() { return instr_range(instr_begin(), instr_end()); }
212 const_instr_range instrs() const {
213 return const_instr_range(instr_begin(), instr_end());
216 iterator begin() { return instr_begin(); }
217 const_iterator begin() const { return instr_begin(); }
218 iterator end () { return instr_end(); }
219 const_iterator end () const { return instr_end(); }
220 reverse_iterator rbegin() {
221 return reverse_iterator::getAtBundleBegin(instr_rbegin());
223 const_reverse_iterator rbegin() const {
224 return const_reverse_iterator::getAtBundleBegin(instr_rbegin());
226 reverse_iterator rend() { return reverse_iterator(instr_rend()); }
227 const_reverse_iterator rend() const {
228 return const_reverse_iterator(instr_rend());
231 /// Support for MachineInstr::getNextNode().
232 static Instructions MachineBasicBlock::*getSublistAccess(MachineInstr *) {
233 return &MachineBasicBlock::Insts;
236 inline iterator_range<iterator> terminators() {
237 return make_range(getFirstTerminator(), end());
239 inline iterator_range<const_iterator> terminators() const {
240 return make_range(getFirstTerminator(), end());
243 /// Returns a range that iterates over the phis in the basic block.
244 inline iterator_range<iterator> phis() {
245 return make_range(begin(), getFirstNonPHI());
247 inline iterator_range<const_iterator> phis() const {
248 return const_cast<MachineBasicBlock *>(this)->phis();
251 // Machine-CFG iterators
252 using pred_iterator = std::vector<MachineBasicBlock *>::iterator;
253 using const_pred_iterator = std::vector<MachineBasicBlock *>::const_iterator;
254 using succ_iterator = std::vector<MachineBasicBlock *>::iterator;
255 using const_succ_iterator = std::vector<MachineBasicBlock *>::const_iterator;
256 using pred_reverse_iterator =
257 std::vector<MachineBasicBlock *>::reverse_iterator;
258 using const_pred_reverse_iterator =
259 std::vector<MachineBasicBlock *>::const_reverse_iterator;
260 using succ_reverse_iterator =
261 std::vector<MachineBasicBlock *>::reverse_iterator;
262 using const_succ_reverse_iterator =
263 std::vector<MachineBasicBlock *>::const_reverse_iterator;
264 pred_iterator pred_begin() { return Predecessors.begin(); }
265 const_pred_iterator pred_begin() const { return Predecessors.begin(); }
266 pred_iterator pred_end() { return Predecessors.end(); }
267 const_pred_iterator pred_end() const { return Predecessors.end(); }
268 pred_reverse_iterator pred_rbegin()
269 { return Predecessors.rbegin();}
270 const_pred_reverse_iterator pred_rbegin() const
271 { return Predecessors.rbegin();}
272 pred_reverse_iterator pred_rend()
273 { return Predecessors.rend(); }
274 const_pred_reverse_iterator pred_rend() const
275 { return Predecessors.rend(); }
276 unsigned pred_size() const {
277 return (unsigned)Predecessors.size();
279 bool pred_empty() const { return Predecessors.empty(); }
280 succ_iterator succ_begin() { return Successors.begin(); }
281 const_succ_iterator succ_begin() const { return Successors.begin(); }
282 succ_iterator succ_end() { return Successors.end(); }
283 const_succ_iterator succ_end() const { return Successors.end(); }
284 succ_reverse_iterator succ_rbegin()
285 { return Successors.rbegin(); }
286 const_succ_reverse_iterator succ_rbegin() const
287 { return Successors.rbegin(); }
288 succ_reverse_iterator succ_rend()
289 { return Successors.rend(); }
290 const_succ_reverse_iterator succ_rend() const
291 { return Successors.rend(); }
292 unsigned succ_size() const {
293 return (unsigned)Successors.size();
295 bool succ_empty() const { return Successors.empty(); }
297 inline iterator_range<pred_iterator> predecessors() {
298 return make_range(pred_begin(), pred_end());
300 inline iterator_range<const_pred_iterator> predecessors() const {
301 return make_range(pred_begin(), pred_end());
303 inline iterator_range<succ_iterator> successors() {
304 return make_range(succ_begin(), succ_end());
306 inline iterator_range<const_succ_iterator> successors() const {
307 return make_range(succ_begin(), succ_end());
310 // LiveIn management methods.
312 /// Adds the specified register as a live in. Note that it is an error to add
313 /// the same register to the same set more than once unless the intention is
314 /// to call sortUniqueLiveIns after all registers are added.
315 void addLiveIn(MCRegister PhysReg,
316 LaneBitmask LaneMask = LaneBitmask::getAll()) {
317 LiveIns.push_back(RegisterMaskPair(PhysReg, LaneMask));
319 void addLiveIn(const RegisterMaskPair &RegMaskPair) {
320 LiveIns.push_back(RegMaskPair);
323 /// Sorts and uniques the LiveIns vector. It can be significantly faster to do
324 /// this than repeatedly calling isLiveIn before calling addLiveIn for every
325 /// LiveIn insertion.
326 void sortUniqueLiveIns();
328 /// Clear live in list.
329 void clearLiveIns();
331 /// Add PhysReg as live in to this block, and ensure that there is a copy of
332 /// PhysReg to a virtual register of class RC. Return the virtual register
333 /// that is a copy of the live in PhysReg.
334 unsigned addLiveIn(MCRegister PhysReg, const TargetRegisterClass *RC);
336 /// Remove the specified register from the live in set.
337 void removeLiveIn(MCPhysReg Reg,
338 LaneBitmask LaneMask = LaneBitmask::getAll());
340 /// Return true if the specified register is in the live in set.
341 bool isLiveIn(MCPhysReg Reg,
342 LaneBitmask LaneMask = LaneBitmask::getAll()) const;
344 // Iteration support for live in sets. These sets are kept in sorted
345 // order by their register number.
346 using livein_iterator = LiveInVector::const_iterator;
347 #ifndef NDEBUG
348 /// Unlike livein_begin, this method does not check that the liveness
349 /// information is accurate. Still for debug purposes it may be useful
350 /// to have iterators that won't assert if the liveness information
351 /// is not current.
352 livein_iterator livein_begin_dbg() const { return LiveIns.begin(); }
353 iterator_range<livein_iterator> liveins_dbg() const {
354 return make_range(livein_begin_dbg(), livein_end());
356 #endif
357 livein_iterator livein_begin() const;
358 livein_iterator livein_end() const { return LiveIns.end(); }
359 bool livein_empty() const { return LiveIns.empty(); }
360 iterator_range<livein_iterator> liveins() const {
361 return make_range(livein_begin(), livein_end());
364 /// Remove entry from the livein set and return iterator to the next.
365 livein_iterator removeLiveIn(livein_iterator I);
367 /// Get the clobber mask for the start of this basic block. Funclets use this
368 /// to prevent register allocation across funclet transitions.
369 const uint32_t *getBeginClobberMask(const TargetRegisterInfo *TRI) const;
371 /// Get the clobber mask for the end of the basic block.
372 /// \see getBeginClobberMask()
373 const uint32_t *getEndClobberMask(const TargetRegisterInfo *TRI) const;
375 /// Return alignment of the basic block.
376 llvm::Align getAlignment() const { return Alignment; }
378 /// Set alignment of the basic block.
379 void setAlignment(llvm::Align A) { Alignment = A; }
381 /// Returns true if the block is a landing pad. That is this basic block is
382 /// entered via an exception handler.
383 bool isEHPad() const { return IsEHPad; }
385 /// Indicates the block is a landing pad. That is this basic block is entered
386 /// via an exception handler.
387 void setIsEHPad(bool V = true) { IsEHPad = V; }
389 bool hasEHPadSuccessor() const;
391 /// Returns true if this is the entry block of an EH scope, i.e., the block
392 /// that used to have a catchpad or cleanuppad instruction in the LLVM IR.
393 bool isEHScopeEntry() const { return IsEHScopeEntry; }
395 /// Indicates if this is the entry block of an EH scope, i.e., the block that
396 /// that used to have a catchpad or cleanuppad instruction in the LLVM IR.
397 void setIsEHScopeEntry(bool V = true) { IsEHScopeEntry = V; }
399 /// Returns true if this is the entry block of an EH funclet.
400 bool isEHFuncletEntry() const { return IsEHFuncletEntry; }
402 /// Indicates if this is the entry block of an EH funclet.
403 void setIsEHFuncletEntry(bool V = true) { IsEHFuncletEntry = V; }
405 /// Returns true if this is the entry block of a cleanup funclet.
406 bool isCleanupFuncletEntry() const { return IsCleanupFuncletEntry; }
408 /// Indicates if this is the entry block of a cleanup funclet.
409 void setIsCleanupFuncletEntry(bool V = true) { IsCleanupFuncletEntry = V; }
411 /// Returns true if it is legal to hoist instructions into this block.
412 bool isLegalToHoistInto() const;
414 // Code Layout methods.
416 /// Move 'this' block before or after the specified block. This only moves
417 /// the block, it does not modify the CFG or adjust potential fall-throughs at
418 /// the end of the block.
419 void moveBefore(MachineBasicBlock *NewAfter);
420 void moveAfter(MachineBasicBlock *NewBefore);
422 /// Update the terminator instructions in block to account for changes to the
423 /// layout. If the block previously used a fallthrough, it may now need a
424 /// branch, and if it previously used branching it may now be able to use a
425 /// fallthrough.
426 void updateTerminator();
428 // Machine-CFG mutators
430 /// Add Succ as a successor of this MachineBasicBlock. The Predecessors list
431 /// of Succ is automatically updated. PROB parameter is stored in
432 /// Probabilities list. The default probability is set as unknown. Mixing
433 /// known and unknown probabilities in successor list is not allowed. When all
434 /// successors have unknown probabilities, 1 / N is returned as the
435 /// probability for each successor, where N is the number of successors.
437 /// Note that duplicate Machine CFG edges are not allowed.
438 void addSuccessor(MachineBasicBlock *Succ,
439 BranchProbability Prob = BranchProbability::getUnknown());
441 /// Add Succ as a successor of this MachineBasicBlock. The Predecessors list
442 /// of Succ is automatically updated. The probability is not provided because
443 /// BPI is not available (e.g. -O0 is used), in which case edge probabilities
444 /// won't be used. Using this interface can save some space.
445 void addSuccessorWithoutProb(MachineBasicBlock *Succ);
447 /// Set successor probability of a given iterator.
448 void setSuccProbability(succ_iterator I, BranchProbability Prob);
450 /// Normalize probabilities of all successors so that the sum of them becomes
451 /// one. This is usually done when the current update on this MBB is done, and
452 /// the sum of its successors' probabilities is not guaranteed to be one. The
453 /// user is responsible for the correct use of this function.
454 /// MBB::removeSuccessor() has an option to do this automatically.
455 void normalizeSuccProbs() {
456 BranchProbability::normalizeProbabilities(Probs.begin(), Probs.end());
459 /// Validate successors' probabilities and check if the sum of them is
460 /// approximate one. This only works in DEBUG mode.
461 void validateSuccProbs() const;
463 /// Remove successor from the successors list of this MachineBasicBlock. The
464 /// Predecessors list of Succ is automatically updated.
465 /// If NormalizeSuccProbs is true, then normalize successors' probabilities
466 /// after the successor is removed.
467 void removeSuccessor(MachineBasicBlock *Succ,
468 bool NormalizeSuccProbs = false);
470 /// Remove specified successor from the successors list of this
471 /// MachineBasicBlock. The Predecessors list of Succ is automatically updated.
472 /// If NormalizeSuccProbs is true, then normalize successors' probabilities
473 /// after the successor is removed.
474 /// Return the iterator to the element after the one removed.
475 succ_iterator removeSuccessor(succ_iterator I,
476 bool NormalizeSuccProbs = false);
478 /// Replace successor OLD with NEW and update probability info.
479 void replaceSuccessor(MachineBasicBlock *Old, MachineBasicBlock *New);
481 /// Copy a successor (and any probability info) from original block to this
482 /// block's. Uses an iterator into the original blocks successors.
484 /// This is useful when doing a partial clone of successors. Afterward, the
485 /// probabilities may need to be normalized.
486 void copySuccessor(MachineBasicBlock *Orig, succ_iterator I);
488 /// Split the old successor into old plus new and updates the probability
489 /// info.
490 void splitSuccessor(MachineBasicBlock *Old, MachineBasicBlock *New,
491 bool NormalizeSuccProbs = false);
493 /// Transfers all the successors from MBB to this machine basic block (i.e.,
494 /// copies all the successors FromMBB and remove all the successors from
495 /// FromMBB).
496 void transferSuccessors(MachineBasicBlock *FromMBB);
498 /// Transfers all the successors, as in transferSuccessors, and update PHI
499 /// operands in the successor blocks which refer to FromMBB to refer to this.
500 void transferSuccessorsAndUpdatePHIs(MachineBasicBlock *FromMBB);
502 /// Return true if any of the successors have probabilities attached to them.
503 bool hasSuccessorProbabilities() const { return !Probs.empty(); }
505 /// Return true if the specified MBB is a predecessor of this block.
506 bool isPredecessor(const MachineBasicBlock *MBB) const;
508 /// Return true if the specified MBB is a successor of this block.
509 bool isSuccessor(const MachineBasicBlock *MBB) const;
511 /// Return true if the specified MBB will be emitted immediately after this
512 /// block, such that if this block exits by falling through, control will
513 /// transfer to the specified MBB. Note that MBB need not be a successor at
514 /// all, for example if this block ends with an unconditional branch to some
515 /// other block.
516 bool isLayoutSuccessor(const MachineBasicBlock *MBB) const;
518 /// Return the fallthrough block if the block can implicitly
519 /// transfer control to the block after it by falling off the end of
520 /// it. This should return null if it can reach the block after
521 /// it, but it uses an explicit branch to do so (e.g., a table
522 /// jump). Non-null return is a conservative answer.
523 MachineBasicBlock *getFallThrough();
525 /// Return true if the block can implicitly transfer control to the
526 /// block after it by falling off the end of it. This should return
527 /// false if it can reach the block after it, but it uses an
528 /// explicit branch to do so (e.g., a table jump). True is a
529 /// conservative answer.
530 bool canFallThrough();
532 /// Returns a pointer to the first instruction in this block that is not a
533 /// PHINode instruction. When adding instructions to the beginning of the
534 /// basic block, they should be added before the returned value, not before
535 /// the first instruction, which might be PHI.
536 /// Returns end() is there's no non-PHI instruction.
537 iterator getFirstNonPHI();
539 /// Return the first instruction in MBB after I that is not a PHI or a label.
540 /// This is the correct point to insert lowered copies at the beginning of a
541 /// basic block that must be before any debugging information.
542 iterator SkipPHIsAndLabels(iterator I);
544 /// Return the first instruction in MBB after I that is not a PHI, label or
545 /// debug. This is the correct point to insert copies at the beginning of a
546 /// basic block.
547 iterator SkipPHIsLabelsAndDebug(iterator I);
549 /// Returns an iterator to the first terminator instruction of this basic
550 /// block. If a terminator does not exist, it returns end().
551 iterator getFirstTerminator();
552 const_iterator getFirstTerminator() const {
553 return const_cast<MachineBasicBlock *>(this)->getFirstTerminator();
556 /// Same getFirstTerminator but it ignores bundles and return an
557 /// instr_iterator instead.
558 instr_iterator getFirstInstrTerminator();
560 /// Returns an iterator to the first non-debug instruction in the basic block,
561 /// or end().
562 iterator getFirstNonDebugInstr();
563 const_iterator getFirstNonDebugInstr() const {
564 return const_cast<MachineBasicBlock *>(this)->getFirstNonDebugInstr();
567 /// Returns an iterator to the last non-debug instruction in the basic block,
568 /// or end().
569 iterator getLastNonDebugInstr();
570 const_iterator getLastNonDebugInstr() const {
571 return const_cast<MachineBasicBlock *>(this)->getLastNonDebugInstr();
574 /// Convenience function that returns true if the block ends in a return
575 /// instruction.
576 bool isReturnBlock() const {
577 return !empty() && back().isReturn();
580 /// Convenience function that returns true if the bock ends in a EH scope
581 /// return instruction.
582 bool isEHScopeReturnBlock() const {
583 return !empty() && back().isEHScopeReturn();
586 /// Split the critical edge from this block to the given successor block, and
587 /// return the newly created block, or null if splitting is not possible.
589 /// This function updates LiveVariables, MachineDominatorTree, and
590 /// MachineLoopInfo, as applicable.
591 MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *Succ, Pass &P);
593 /// Check if the edge between this block and the given successor \p
594 /// Succ, can be split. If this returns true a subsequent call to
595 /// SplitCriticalEdge is guaranteed to return a valid basic block if
596 /// no changes occurred in the meantime.
597 bool canSplitCriticalEdge(const MachineBasicBlock *Succ) const;
599 void pop_front() { Insts.pop_front(); }
600 void pop_back() { Insts.pop_back(); }
601 void push_back(MachineInstr *MI) { Insts.push_back(MI); }
603 /// Insert MI into the instruction list before I, possibly inside a bundle.
605 /// If the insertion point is inside a bundle, MI will be added to the bundle,
606 /// otherwise MI will not be added to any bundle. That means this function
607 /// alone can't be used to prepend or append instructions to bundles. See
608 /// MIBundleBuilder::insert() for a more reliable way of doing that.
609 instr_iterator insert(instr_iterator I, MachineInstr *M);
611 /// Insert a range of instructions into the instruction list before I.
612 template<typename IT>
613 void insert(iterator I, IT S, IT E) {
614 assert((I == end() || I->getParent() == this) &&
615 "iterator points outside of basic block");
616 Insts.insert(I.getInstrIterator(), S, E);
619 /// Insert MI into the instruction list before I.
620 iterator insert(iterator I, MachineInstr *MI) {
621 assert((I == end() || I->getParent() == this) &&
622 "iterator points outside of basic block");
623 assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
624 "Cannot insert instruction with bundle flags");
625 return Insts.insert(I.getInstrIterator(), MI);
628 /// Insert MI into the instruction list after I.
629 iterator insertAfter(iterator I, MachineInstr *MI) {
630 assert((I == end() || I->getParent() == this) &&
631 "iterator points outside of basic block");
632 assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
633 "Cannot insert instruction with bundle flags");
634 return Insts.insertAfter(I.getInstrIterator(), MI);
637 /// If I is bundled then insert MI into the instruction list after the end of
638 /// the bundle, otherwise insert MI immediately after I.
639 instr_iterator insertAfterBundle(instr_iterator I, MachineInstr *MI) {
640 assert((I == instr_end() || I->getParent() == this) &&
641 "iterator points outside of basic block");
642 assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
643 "Cannot insert instruction with bundle flags");
644 while (I->isBundledWithSucc())
645 ++I;
646 return Insts.insertAfter(I, MI);
649 /// Remove an instruction from the instruction list and delete it.
651 /// If the instruction is part of a bundle, the other instructions in the
652 /// bundle will still be bundled after removing the single instruction.
653 instr_iterator erase(instr_iterator I);
655 /// Remove an instruction from the instruction list and delete it.
657 /// If the instruction is part of a bundle, the other instructions in the
658 /// bundle will still be bundled after removing the single instruction.
659 instr_iterator erase_instr(MachineInstr *I) {
660 return erase(instr_iterator(I));
663 /// Remove a range of instructions from the instruction list and delete them.
664 iterator erase(iterator I, iterator E) {
665 return Insts.erase(I.getInstrIterator(), E.getInstrIterator());
668 /// Remove an instruction or bundle from the instruction list and delete it.
670 /// If I points to a bundle of instructions, they are all erased.
671 iterator erase(iterator I) {
672 return erase(I, std::next(I));
675 /// Remove an instruction from the instruction list and delete it.
677 /// If I is the head of a bundle of instructions, the whole bundle will be
678 /// erased.
679 iterator erase(MachineInstr *I) {
680 return erase(iterator(I));
683 /// Remove the unbundled instruction from the instruction list without
684 /// deleting it.
686 /// This function can not be used to remove bundled instructions, use
687 /// remove_instr to remove individual instructions from a bundle.
688 MachineInstr *remove(MachineInstr *I) {
689 assert(!I->isBundled() && "Cannot remove bundled instructions");
690 return Insts.remove(instr_iterator(I));
693 /// Remove the possibly bundled instruction from the instruction list
694 /// without deleting it.
696 /// If the instruction is part of a bundle, the other instructions in the
697 /// bundle will still be bundled after removing the single instruction.
698 MachineInstr *remove_instr(MachineInstr *I);
700 void clear() {
701 Insts.clear();
704 /// Take an instruction from MBB 'Other' at the position From, and insert it
705 /// into this MBB right before 'Where'.
707 /// If From points to a bundle of instructions, the whole bundle is moved.
708 void splice(iterator Where, MachineBasicBlock *Other, iterator From) {
709 // The range splice() doesn't allow noop moves, but this one does.
710 if (Where != From)
711 splice(Where, Other, From, std::next(From));
714 /// Take a block of instructions from MBB 'Other' in the range [From, To),
715 /// and insert them into this MBB right before 'Where'.
717 /// The instruction at 'Where' must not be included in the range of
718 /// instructions to move.
719 void splice(iterator Where, MachineBasicBlock *Other,
720 iterator From, iterator To) {
721 Insts.splice(Where.getInstrIterator(), Other->Insts,
722 From.getInstrIterator(), To.getInstrIterator());
725 /// This method unlinks 'this' from the containing function, and returns it,
726 /// but does not delete it.
727 MachineBasicBlock *removeFromParent();
729 /// This method unlinks 'this' from the containing function and deletes it.
730 void eraseFromParent();
732 /// Given a machine basic block that branched to 'Old', change the code and
733 /// CFG so that it branches to 'New' instead.
734 void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New);
736 /// Update all phi nodes in this basic block to refer to basic block \p New
737 /// instead of basic block \p Old.
738 void replacePhiUsesWith(MachineBasicBlock *Old, MachineBasicBlock *New);
740 /// Various pieces of code can cause excess edges in the CFG to be inserted.
741 /// If we have proven that MBB can only branch to DestA and DestB, remove any
742 /// other MBB successors from the CFG. DestA and DestB can be null. Besides
743 /// DestA and DestB, retain other edges leading to LandingPads (currently
744 /// there can be only one; we don't check or require that here). Note it is
745 /// possible that DestA and/or DestB are LandingPads.
746 bool CorrectExtraCFGEdges(MachineBasicBlock *DestA,
747 MachineBasicBlock *DestB,
748 bool IsCond);
750 /// Find the next valid DebugLoc starting at MBBI, skipping any DBG_VALUE
751 /// and DBG_LABEL instructions. Return UnknownLoc if there is none.
752 DebugLoc findDebugLoc(instr_iterator MBBI);
753 DebugLoc findDebugLoc(iterator MBBI) {
754 return findDebugLoc(MBBI.getInstrIterator());
757 /// Find the previous valid DebugLoc preceding MBBI, skipping and DBG_VALUE
758 /// instructions. Return UnknownLoc if there is none.
759 DebugLoc findPrevDebugLoc(instr_iterator MBBI);
760 DebugLoc findPrevDebugLoc(iterator MBBI) {
761 return findPrevDebugLoc(MBBI.getInstrIterator());
764 /// Find and return the merged DebugLoc of the branch instructions of the
765 /// block. Return UnknownLoc if there is none.
766 DebugLoc findBranchDebugLoc();
768 /// Possible outcome of a register liveness query to computeRegisterLiveness()
769 enum LivenessQueryResult {
770 LQR_Live, ///< Register is known to be (at least partially) live.
771 LQR_Dead, ///< Register is known to be fully dead.
772 LQR_Unknown ///< Register liveness not decidable from local neighborhood.
775 /// Return whether (physical) register \p Reg has been defined and not
776 /// killed as of just before \p Before.
778 /// Search is localised to a neighborhood of \p Neighborhood instructions
779 /// before (searching for defs or kills) and \p Neighborhood instructions
780 /// after (searching just for defs) \p Before.
782 /// \p Reg must be a physical register.
783 LivenessQueryResult computeRegisterLiveness(const TargetRegisterInfo *TRI,
784 unsigned Reg,
785 const_iterator Before,
786 unsigned Neighborhood = 10) const;
788 // Debugging methods.
789 void dump() const;
790 void print(raw_ostream &OS, const SlotIndexes * = nullptr,
791 bool IsStandalone = true) const;
792 void print(raw_ostream &OS, ModuleSlotTracker &MST,
793 const SlotIndexes * = nullptr, bool IsStandalone = true) const;
795 // Printing method used by LoopInfo.
796 void printAsOperand(raw_ostream &OS, bool PrintType = true) const;
798 /// MachineBasicBlocks are uniquely numbered at the function level, unless
799 /// they're not in a MachineFunction yet, in which case this will return -1.
800 int getNumber() const { return Number; }
801 void setNumber(int N) { Number = N; }
803 /// Return the MCSymbol for this basic block.
804 MCSymbol *getSymbol() const;
806 Optional<uint64_t> getIrrLoopHeaderWeight() const {
807 return IrrLoopHeaderWeight;
810 void setIrrLoopHeaderWeight(uint64_t Weight) {
811 IrrLoopHeaderWeight = Weight;
814 private:
815 /// Return probability iterator corresponding to the I successor iterator.
816 probability_iterator getProbabilityIterator(succ_iterator I);
817 const_probability_iterator
818 getProbabilityIterator(const_succ_iterator I) const;
820 friend class MachineBranchProbabilityInfo;
821 friend class MIPrinter;
823 /// Return probability of the edge from this block to MBB. This method should
824 /// NOT be called directly, but by using getEdgeProbability method from
825 /// MachineBranchProbabilityInfo class.
826 BranchProbability getSuccProbability(const_succ_iterator Succ) const;
828 // Methods used to maintain doubly linked list of blocks...
829 friend struct ilist_callback_traits<MachineBasicBlock>;
831 // Machine-CFG mutators
833 /// Add Pred as a predecessor of this MachineBasicBlock. Don't do this
834 /// unless you know what you're doing, because it doesn't update Pred's
835 /// successors list. Use Pred->addSuccessor instead.
836 void addPredecessor(MachineBasicBlock *Pred);
838 /// Remove Pred as a predecessor of this MachineBasicBlock. Don't do this
839 /// unless you know what you're doing, because it doesn't update Pred's
840 /// successors list. Use Pred->removeSuccessor instead.
841 void removePredecessor(MachineBasicBlock *Pred);
844 raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB);
846 /// Prints a machine basic block reference.
848 /// The format is:
849 /// %bb.5 - a machine basic block with MBB.getNumber() == 5.
851 /// Usage: OS << printMBBReference(MBB) << '\n';
852 Printable printMBBReference(const MachineBasicBlock &MBB);
854 // This is useful when building IndexedMaps keyed on basic block pointers.
855 struct MBB2NumberFunctor {
856 using argument_type = const MachineBasicBlock *;
857 unsigned operator()(const MachineBasicBlock *MBB) const {
858 return MBB->getNumber();
862 //===--------------------------------------------------------------------===//
863 // GraphTraits specializations for machine basic block graphs (machine-CFGs)
864 //===--------------------------------------------------------------------===//
866 // Provide specializations of GraphTraits to be able to treat a
867 // MachineFunction as a graph of MachineBasicBlocks.
870 template <> struct GraphTraits<MachineBasicBlock *> {
871 using NodeRef = MachineBasicBlock *;
872 using ChildIteratorType = MachineBasicBlock::succ_iterator;
874 static NodeRef getEntryNode(MachineBasicBlock *BB) { return BB; }
875 static ChildIteratorType child_begin(NodeRef N) { return N->succ_begin(); }
876 static ChildIteratorType child_end(NodeRef N) { return N->succ_end(); }
879 template <> struct GraphTraits<const MachineBasicBlock *> {
880 using NodeRef = const MachineBasicBlock *;
881 using ChildIteratorType = MachineBasicBlock::const_succ_iterator;
883 static NodeRef getEntryNode(const MachineBasicBlock *BB) { return BB; }
884 static ChildIteratorType child_begin(NodeRef N) { return N->succ_begin(); }
885 static ChildIteratorType child_end(NodeRef N) { return N->succ_end(); }
888 // Provide specializations of GraphTraits to be able to treat a
889 // MachineFunction as a graph of MachineBasicBlocks and to walk it
890 // in inverse order. Inverse order for a function is considered
891 // to be when traversing the predecessor edges of a MBB
892 // instead of the successor edges.
894 template <> struct GraphTraits<Inverse<MachineBasicBlock*>> {
895 using NodeRef = MachineBasicBlock *;
896 using ChildIteratorType = MachineBasicBlock::pred_iterator;
898 static NodeRef getEntryNode(Inverse<MachineBasicBlock *> G) {
899 return G.Graph;
902 static ChildIteratorType child_begin(NodeRef N) { return N->pred_begin(); }
903 static ChildIteratorType child_end(NodeRef N) { return N->pred_end(); }
906 template <> struct GraphTraits<Inverse<const MachineBasicBlock*>> {
907 using NodeRef = const MachineBasicBlock *;
908 using ChildIteratorType = MachineBasicBlock::const_pred_iterator;
910 static NodeRef getEntryNode(Inverse<const MachineBasicBlock *> G) {
911 return G.Graph;
914 static ChildIteratorType child_begin(NodeRef N) { return N->pred_begin(); }
915 static ChildIteratorType child_end(NodeRef N) { return N->pred_end(); }
918 /// MachineInstrSpan provides an interface to get an iteration range
919 /// containing the instruction it was initialized with, along with all
920 /// those instructions inserted prior to or following that instruction
921 /// at some point after the MachineInstrSpan is constructed.
922 class MachineInstrSpan {
923 MachineBasicBlock &MBB;
924 MachineBasicBlock::iterator I, B, E;
926 public:
927 MachineInstrSpan(MachineBasicBlock::iterator I, MachineBasicBlock *BB)
928 : MBB(*BB), I(I), B(I == MBB.begin() ? MBB.end() : std::prev(I)),
929 E(std::next(I)) {
930 assert(I == BB->end() || I->getParent() == BB);
933 MachineBasicBlock::iterator begin() {
934 return B == MBB.end() ? MBB.begin() : std::next(B);
936 MachineBasicBlock::iterator end() { return E; }
937 bool empty() { return begin() == end(); }
939 MachineBasicBlock::iterator getInitial() { return I; }
942 /// Increment \p It until it points to a non-debug instruction or to \p End
943 /// and return the resulting iterator. This function should only be used
944 /// MachineBasicBlock::{iterator, const_iterator, instr_iterator,
945 /// const_instr_iterator} and the respective reverse iterators.
946 template<typename IterT>
947 inline IterT skipDebugInstructionsForward(IterT It, IterT End) {
948 while (It != End && It->isDebugInstr())
949 It++;
950 return It;
953 /// Decrement \p It until it points to a non-debug instruction or to \p Begin
954 /// and return the resulting iterator. This function should only be used
955 /// MachineBasicBlock::{iterator, const_iterator, instr_iterator,
956 /// const_instr_iterator} and the respective reverse iterators.
957 template<class IterT>
958 inline IterT skipDebugInstructionsBackward(IterT It, IterT Begin) {
959 while (It != Begin && It->isDebugInstr())
960 It--;
961 return It;
964 } // end namespace llvm
966 #endif // LLVM_CODEGEN_MACHINEBASICBLOCK_H