1 //===- llvm/CodeGen/SlotIndexes.h - Slot indexes representation -*- 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 // This file implements SlotIndex and related classes. The purpose of SlotIndex
11 // is to describe a position at which a register can become live, or cease to
14 // SlotIndex is mostly a proxy for entries of the SlotIndexList, a class which
15 // is held is LiveIntervals and provides the real numbering. This allows
16 // LiveIntervals to perform largely transparent renumbering.
17 //===----------------------------------------------------------------------===//
19 #ifndef LLVM_CODEGEN_SLOTINDEXES_H
20 #define LLVM_CODEGEN_SLOTINDEXES_H
22 #include "llvm/ADT/DenseMap.h"
23 #include "llvm/ADT/IntervalMap.h"
24 #include "llvm/ADT/PointerIntPair.h"
25 #include "llvm/ADT/SmallVector.h"
26 #include "llvm/ADT/ilist.h"
27 #include "llvm/CodeGen/MachineFunction.h"
28 #include "llvm/CodeGen/MachineFunctionPass.h"
29 #include "llvm/CodeGen/MachineInstrBundle.h"
30 #include "llvm/Support/Allocator.h"
34 /// This class represents an entry in the slot index list held in the
35 /// SlotIndexes pass. It should not be used directly. See the
36 /// SlotIndex & SlotIndexes classes for the public interface to this
38 class IndexListEntry : public ilist_node<IndexListEntry> {
44 IndexListEntry(MachineInstr *mi, unsigned index) : mi(mi), index(index) {}
46 MachineInstr* getInstr() const { return mi; }
47 void setInstr(MachineInstr *mi) {
51 unsigned getIndex() const { return index; }
52 void setIndex(unsigned index) {
56 #ifdef EXPENSIVE_CHECKS
57 // When EXPENSIVE_CHECKS is defined, "erased" index list entries will
58 // actually be moved to a "graveyard" list, and have their pointers
59 // poisoned, so that dangling SlotIndex access can be reliably detected.
61 intptr_t tmp = reinterpret_cast<intptr_t>(mi);
62 assert(((tmp & 0x1) == 0x0) && "Pointer already poisoned?");
64 mi = reinterpret_cast<MachineInstr*>(tmp);
67 bool isPoisoned() const { return (reinterpret_cast<intptr_t>(mi) & 0x1) == 0x1; }
68 #endif // EXPENSIVE_CHECKS
73 struct ilist_traits<IndexListEntry> : public ilist_default_traits<IndexListEntry> {
75 mutable ilist_half_node<IndexListEntry> Sentinel;
77 IndexListEntry *createSentinel() const {
78 return static_cast<IndexListEntry*>(&Sentinel);
80 void destroySentinel(IndexListEntry *) const {}
82 IndexListEntry *provideInitialHead() const { return createSentinel(); }
83 IndexListEntry *ensureHead(IndexListEntry*) const { return createSentinel(); }
84 static void noteHead(IndexListEntry*, IndexListEntry*) {}
85 void deleteNode(IndexListEntry *N) {}
88 void createNode(const IndexListEntry &);
91 /// SlotIndex - An opaque wrapper around machine indexes.
93 friend class SlotIndexes;
96 /// Basic block boundary. Used for live ranges entering and leaving a
97 /// block without being live in the layout neighbor. Also used as the
98 /// def slot of PHI-defs.
101 /// Early-clobber register use/def slot. A live range defined at
102 /// Slot_EarlyCLobber interferes with normal live ranges killed at
103 /// Slot_Register. Also used as the kill slot for live ranges tied to an
104 /// early-clobber def.
107 /// Normal register use/def slot. Normal instructions kill and define
108 /// register live ranges at this slot.
111 /// Dead def kill point. Kill slot for a live range that is defined by
112 /// the same instruction (Slot_Register or Slot_EarlyClobber), but isn't
119 PointerIntPair<IndexListEntry*, 2, unsigned> lie;
121 SlotIndex(IndexListEntry *entry, unsigned slot)
122 : lie(entry, slot) {}
124 IndexListEntry* listEntry() const {
125 assert(isValid() && "Attempt to compare reserved index.");
126 #ifdef EXPENSIVE_CHECKS
127 assert(!lie.getPointer()->isPoisoned() &&
128 "Attempt to access deleted list-entry.");
129 #endif // EXPENSIVE_CHECKS
130 return lie.getPointer();
133 unsigned getIndex() const {
134 return listEntry()->getIndex() | getSlot();
137 /// Returns the slot for this SlotIndex.
138 Slot getSlot() const {
139 return static_cast<Slot>(lie.getInt());
144 /// The default distance between instructions as returned by distance().
145 /// This may vary as instructions are inserted and removed.
146 InstrDist = 4 * Slot_Count
149 /// Construct an invalid index.
150 SlotIndex() : lie(0, 0) {}
152 // Construct a new slot index from the given one, and set the slot.
153 SlotIndex(const SlotIndex &li, Slot s) : lie(li.listEntry(), unsigned(s)) {
154 assert(lie.getPointer() != 0 &&
155 "Attempt to construct index with 0 pointer.");
158 /// Returns true if this is a valid index. Invalid indicies do
159 /// not point into an index table, and cannot be compared.
160 bool isValid() const {
161 return lie.getPointer();
164 /// Return true for a valid index.
165 LLVM_EXPLICIT operator bool() const { return isValid(); }
167 /// Print this index to the given raw_ostream.
168 void print(raw_ostream &os) const;
170 /// Dump this index to stderr.
173 /// Compare two SlotIndex objects for equality.
174 bool operator==(SlotIndex other) const {
175 return lie == other.lie;
177 /// Compare two SlotIndex objects for inequality.
178 bool operator!=(SlotIndex other) const {
179 return lie != other.lie;
182 /// Compare two SlotIndex objects. Return true if the first index
183 /// is strictly lower than the second.
184 bool operator<(SlotIndex other) const {
185 return getIndex() < other.getIndex();
187 /// Compare two SlotIndex objects. Return true if the first index
188 /// is lower than, or equal to, the second.
189 bool operator<=(SlotIndex other) const {
190 return getIndex() <= other.getIndex();
193 /// Compare two SlotIndex objects. Return true if the first index
194 /// is greater than the second.
195 bool operator>(SlotIndex other) const {
196 return getIndex() > other.getIndex();
199 /// Compare two SlotIndex objects. Return true if the first index
200 /// is greater than, or equal to, the second.
201 bool operator>=(SlotIndex other) const {
202 return getIndex() >= other.getIndex();
205 /// isSameInstr - Return true if A and B refer to the same instruction.
206 static bool isSameInstr(SlotIndex A, SlotIndex B) {
207 return A.lie.getPointer() == B.lie.getPointer();
210 /// isEarlierInstr - Return true if A refers to an instruction earlier than
211 /// B. This is equivalent to A < B && !isSameInstr(A, B).
212 static bool isEarlierInstr(SlotIndex A, SlotIndex B) {
213 return A.listEntry()->getIndex() < B.listEntry()->getIndex();
216 /// Return the distance from this index to the given one.
217 int distance(SlotIndex other) const {
218 return other.getIndex() - getIndex();
221 /// Return the scaled distance from this index to the given one, where all
222 /// slots on the same instruction have zero distance.
223 int getInstrDistance(SlotIndex other) const {
224 return (other.listEntry()->getIndex() - listEntry()->getIndex())
228 /// isBlock - Returns true if this is a block boundary slot.
229 bool isBlock() const { return getSlot() == Slot_Block; }
231 /// isEarlyClobber - Returns true if this is an early-clobber slot.
232 bool isEarlyClobber() const { return getSlot() == Slot_EarlyClobber; }
234 /// isRegister - Returns true if this is a normal register use/def slot.
235 /// Note that early-clobber slots may also be used for uses and defs.
236 bool isRegister() const { return getSlot() == Slot_Register; }
238 /// isDead - Returns true if this is a dead def kill slot.
239 bool isDead() const { return getSlot() == Slot_Dead; }
241 /// Returns the base index for associated with this index. The base index
242 /// is the one associated with the Slot_Block slot for the instruction
243 /// pointed to by this index.
244 SlotIndex getBaseIndex() const {
245 return SlotIndex(listEntry(), Slot_Block);
248 /// Returns the boundary index for associated with this index. The boundary
249 /// index is the one associated with the Slot_Block slot for the instruction
250 /// pointed to by this index.
251 SlotIndex getBoundaryIndex() const {
252 return SlotIndex(listEntry(), Slot_Dead);
255 /// Returns the register use/def slot in the current instruction for a
256 /// normal or early-clobber def.
257 SlotIndex getRegSlot(bool EC = false) const {
258 return SlotIndex(listEntry(), EC ? Slot_EarlyClobber : Slot_Register);
261 /// Returns the dead def kill slot for the current instruction.
262 SlotIndex getDeadSlot() const {
263 return SlotIndex(listEntry(), Slot_Dead);
266 /// Returns the next slot in the index list. This could be either the
267 /// next slot for the instruction pointed to by this index or, if this
268 /// index is a STORE, the first slot for the next instruction.
269 /// WARNING: This method is considerably more expensive than the methods
270 /// that return specific slots (getUseIndex(), etc). If you can - please
271 /// use one of those methods.
272 SlotIndex getNextSlot() const {
274 if (s == Slot_Dead) {
275 return SlotIndex(listEntry()->getNextNode(), Slot_Block);
277 return SlotIndex(listEntry(), s + 1);
280 /// Returns the next index. This is the index corresponding to the this
281 /// index's slot, but for the next instruction.
282 SlotIndex getNextIndex() const {
283 return SlotIndex(listEntry()->getNextNode(), getSlot());
286 /// Returns the previous slot in the index list. This could be either the
287 /// previous slot for the instruction pointed to by this index or, if this
288 /// index is a Slot_Block, the last slot for the previous instruction.
289 /// WARNING: This method is considerably more expensive than the methods
290 /// that return specific slots (getUseIndex(), etc). If you can - please
291 /// use one of those methods.
292 SlotIndex getPrevSlot() const {
294 if (s == Slot_Block) {
295 return SlotIndex(listEntry()->getPrevNode(), Slot_Dead);
297 return SlotIndex(listEntry(), s - 1);
300 /// Returns the previous index. This is the index corresponding to this
301 /// index's slot, but for the previous instruction.
302 SlotIndex getPrevIndex() const {
303 return SlotIndex(listEntry()->getPrevNode(), getSlot());
308 template <> struct isPodLike<SlotIndex> { static const bool value = true; };
310 inline raw_ostream& operator<<(raw_ostream &os, SlotIndex li) {
315 typedef std::pair<SlotIndex, MachineBasicBlock*> IdxMBBPair;
317 inline bool operator<(SlotIndex V, const IdxMBBPair &IM) {
321 inline bool operator<(const IdxMBBPair &IM, SlotIndex V) {
325 struct Idx2MBBCompare {
326 bool operator()(const IdxMBBPair &LHS, const IdxMBBPair &RHS) const {
327 return LHS.first < RHS.first;
331 /// SlotIndexes pass.
333 /// This pass assigns indexes to each instruction.
334 class SlotIndexes : public MachineFunctionPass {
337 typedef ilist<IndexListEntry> IndexList;
340 #ifdef EXPENSIVE_CHECKS
341 IndexList graveyardList;
342 #endif // EXPENSIVE_CHECKS
346 typedef DenseMap<const MachineInstr*, SlotIndex> Mi2IndexMap;
349 /// MBBRanges - Map MBB number to (start, stop) indexes.
350 SmallVector<std::pair<SlotIndex, SlotIndex>, 8> MBBRanges;
352 /// Idx2MBBMap - Sorted list of pairs of index of first instruction
354 SmallVector<IdxMBBPair, 8> idx2MBBMap;
356 // IndexListEntry allocator.
357 BumpPtrAllocator ileAllocator;
359 IndexListEntry* createEntry(MachineInstr *mi, unsigned index) {
360 IndexListEntry *entry =
361 static_cast<IndexListEntry*>(
362 ileAllocator.Allocate(sizeof(IndexListEntry),
363 alignOf<IndexListEntry>()));
365 new (entry) IndexListEntry(mi, index);
370 /// Renumber locally after inserting curItr.
371 void renumberIndexes(IndexList::iterator curItr);
376 SlotIndexes() : MachineFunctionPass(ID) {
377 initializeSlotIndexesPass(*PassRegistry::getPassRegistry());
380 virtual void getAnalysisUsage(AnalysisUsage &au) const;
381 virtual void releaseMemory();
383 virtual bool runOnMachineFunction(MachineFunction &fn);
385 /// Dump the indexes.
388 /// Renumber the index list, providing space for new instructions.
389 void renumberIndexes();
391 /// Repair indexes after adding and removing instructions.
392 void repairIndexesInRange(MachineBasicBlock *MBB,
393 MachineBasicBlock::iterator Begin,
394 MachineBasicBlock::iterator End);
396 /// Returns the zero index for this analysis.
397 SlotIndex getZeroIndex() {
398 assert(indexList.front().getIndex() == 0 && "First index is not 0?");
399 return SlotIndex(&indexList.front(), 0);
402 /// Returns the base index of the last slot in this analysis.
403 SlotIndex getLastIndex() {
404 return SlotIndex(&indexList.back(), 0);
407 /// Returns true if the given machine instr is mapped to an index,
408 /// otherwise returns false.
409 bool hasIndex(const MachineInstr *instr) const {
410 return mi2iMap.count(instr);
413 /// Returns the base index for the given instruction.
414 SlotIndex getInstructionIndex(const MachineInstr *MI) const {
415 // Instructions inside a bundle have the same number as the bundle itself.
416 Mi2IndexMap::const_iterator itr = mi2iMap.find(getBundleStart(MI));
417 assert(itr != mi2iMap.end() && "Instruction not found in maps.");
421 /// Returns the instruction for the given index, or null if the given
422 /// index has no instruction associated with it.
423 MachineInstr* getInstructionFromIndex(SlotIndex index) const {
424 return index.isValid() ? index.listEntry()->getInstr() : 0;
427 /// Returns the next non-null index, if one exists.
428 /// Otherwise returns getLastIndex().
429 SlotIndex getNextNonNullIndex(SlotIndex Index) {
430 IndexList::iterator I = Index.listEntry();
431 IndexList::iterator E = indexList.end();
434 return SlotIndex(I, Index.getSlot());
435 // We reached the end of the function.
436 return getLastIndex();
439 /// getIndexBefore - Returns the index of the last indexed instruction
440 /// before MI, or the start index of its basic block.
441 /// MI is not required to have an index.
442 SlotIndex getIndexBefore(const MachineInstr *MI) const {
443 const MachineBasicBlock *MBB = MI->getParent();
444 assert(MBB && "MI must be inserted inna basic block");
445 MachineBasicBlock::const_iterator I = MI, B = MBB->begin();
448 return getMBBStartIdx(MBB);
450 Mi2IndexMap::const_iterator MapItr = mi2iMap.find(I);
451 if (MapItr != mi2iMap.end())
452 return MapItr->second;
456 /// getIndexAfter - Returns the index of the first indexed instruction
457 /// after MI, or the end index of its basic block.
458 /// MI is not required to have an index.
459 SlotIndex getIndexAfter(const MachineInstr *MI) const {
460 const MachineBasicBlock *MBB = MI->getParent();
461 assert(MBB && "MI must be inserted inna basic block");
462 MachineBasicBlock::const_iterator I = MI, E = MBB->end();
466 return getMBBEndIdx(MBB);
467 Mi2IndexMap::const_iterator MapItr = mi2iMap.find(I);
468 if (MapItr != mi2iMap.end())
469 return MapItr->second;
473 /// Return the (start,end) range of the given basic block number.
474 const std::pair<SlotIndex, SlotIndex> &
475 getMBBRange(unsigned Num) const {
476 return MBBRanges[Num];
479 /// Return the (start,end) range of the given basic block.
480 const std::pair<SlotIndex, SlotIndex> &
481 getMBBRange(const MachineBasicBlock *MBB) const {
482 return getMBBRange(MBB->getNumber());
485 /// Returns the first index in the given basic block number.
486 SlotIndex getMBBStartIdx(unsigned Num) const {
487 return getMBBRange(Num).first;
490 /// Returns the first index in the given basic block.
491 SlotIndex getMBBStartIdx(const MachineBasicBlock *mbb) const {
492 return getMBBRange(mbb).first;
495 /// Returns the last index in the given basic block number.
496 SlotIndex getMBBEndIdx(unsigned Num) const {
497 return getMBBRange(Num).second;
500 /// Returns the last index in the given basic block.
501 SlotIndex getMBBEndIdx(const MachineBasicBlock *mbb) const {
502 return getMBBRange(mbb).second;
505 /// Returns the basic block which the given index falls in.
506 MachineBasicBlock* getMBBFromIndex(SlotIndex index) const {
507 if (MachineInstr *MI = getInstructionFromIndex(index))
508 return MI->getParent();
509 SmallVectorImpl<IdxMBBPair>::const_iterator I =
510 std::lower_bound(idx2MBBMap.begin(), idx2MBBMap.end(), index);
511 // Take the pair containing the index
512 SmallVectorImpl<IdxMBBPair>::const_iterator J =
513 ((I != idx2MBBMap.end() && I->first > index) ||
514 (I == idx2MBBMap.end() && idx2MBBMap.size()>0)) ? (I-1): I;
516 assert(J != idx2MBBMap.end() && J->first <= index &&
517 index < getMBBEndIdx(J->second) &&
518 "index does not correspond to an MBB");
522 bool findLiveInMBBs(SlotIndex start, SlotIndex end,
523 SmallVectorImpl<MachineBasicBlock*> &mbbs) const {
524 SmallVectorImpl<IdxMBBPair>::const_iterator itr =
525 std::lower_bound(idx2MBBMap.begin(), idx2MBBMap.end(), start);
528 while (itr != idx2MBBMap.end()) {
529 if (itr->first >= end)
531 mbbs.push_back(itr->second);
538 /// Returns the MBB covering the given range, or null if the range covers
539 /// more than one basic block.
540 MachineBasicBlock* getMBBCoveringRange(SlotIndex start, SlotIndex end) const {
542 assert(start < end && "Backwards ranges not allowed.");
544 SmallVectorImpl<IdxMBBPair>::const_iterator itr =
545 std::lower_bound(idx2MBBMap.begin(), idx2MBBMap.end(), start);
547 if (itr == idx2MBBMap.end()) {
552 // Check that we don't cross the boundary into this block.
553 if (itr->first < end)
558 if (itr->first <= start)
564 /// Insert the given machine instruction into the mapping. Returns the
566 /// If Late is set and there are null indexes between mi's neighboring
567 /// instructions, create the new index after the null indexes instead of
569 SlotIndex insertMachineInstrInMaps(MachineInstr *mi, bool Late = false) {
570 assert(!mi->isInsideBundle() &&
571 "Instructions inside bundles should use bundle start's slot.");
572 assert(mi2iMap.find(mi) == mi2iMap.end() && "Instr already indexed.");
573 // Numbering DBG_VALUE instructions could cause code generation to be
574 // affected by debug information.
575 assert(!mi->isDebugValue() && "Cannot number DBG_VALUE instructions.");
577 assert(mi->getParent() != 0 && "Instr must be added to function.");
579 // Get the entries where mi should be inserted.
580 IndexList::iterator prevItr, nextItr;
582 // Insert mi's index immediately before the following instruction.
583 nextItr = getIndexAfter(mi).listEntry();
584 prevItr = prior(nextItr);
586 // Insert mi's index immediately after the preceding instruction.
587 prevItr = getIndexBefore(mi).listEntry();
588 nextItr = llvm::next(prevItr);
591 // Get a number for the new instr, or 0 if there's no room currently.
592 // In the latter case we'll force a renumber later.
593 unsigned dist = ((nextItr->getIndex() - prevItr->getIndex())/2) & ~3u;
594 unsigned newNumber = prevItr->getIndex() + dist;
596 // Insert a new list entry for mi.
597 IndexList::iterator newItr =
598 indexList.insert(nextItr, createEntry(mi, newNumber));
600 // Renumber locally if we need to.
602 renumberIndexes(newItr);
604 SlotIndex newIndex(&*newItr, SlotIndex::Slot_Block);
605 mi2iMap.insert(std::make_pair(mi, newIndex));
609 /// Remove the given machine instruction from the mapping.
610 void removeMachineInstrFromMaps(MachineInstr *mi) {
611 // remove index -> MachineInstr and
612 // MachineInstr -> index mappings
613 Mi2IndexMap::iterator mi2iItr = mi2iMap.find(mi);
614 if (mi2iItr != mi2iMap.end()) {
615 IndexListEntry *miEntry(mi2iItr->second.listEntry());
616 assert(miEntry->getInstr() == mi && "Instruction indexes broken.");
617 // FIXME: Eventually we want to actually delete these indexes.
618 miEntry->setInstr(0);
619 mi2iMap.erase(mi2iItr);
623 /// ReplaceMachineInstrInMaps - Replacing a machine instr with a new one in
624 /// maps used by register allocator.
625 void replaceMachineInstrInMaps(MachineInstr *mi, MachineInstr *newMI) {
626 Mi2IndexMap::iterator mi2iItr = mi2iMap.find(mi);
627 if (mi2iItr == mi2iMap.end())
629 SlotIndex replaceBaseIndex = mi2iItr->second;
630 IndexListEntry *miEntry(replaceBaseIndex.listEntry());
631 assert(miEntry->getInstr() == mi &&
632 "Mismatched instruction in index tables.");
633 miEntry->setInstr(newMI);
634 mi2iMap.erase(mi2iItr);
635 mi2iMap.insert(std::make_pair(newMI, replaceBaseIndex));
638 /// Add the given MachineBasicBlock into the maps.
639 void insertMBBInMaps(MachineBasicBlock *mbb) {
640 MachineFunction::iterator nextMBB =
641 llvm::next(MachineFunction::iterator(mbb));
643 IndexListEntry *startEntry = 0;
644 IndexListEntry *endEntry = 0;
645 IndexList::iterator newItr;
646 if (nextMBB == mbb->getParent()->end()) {
647 startEntry = &indexList.back();
648 endEntry = createEntry(0, 0);
649 newItr = indexList.insertAfter(startEntry, endEntry);
651 startEntry = createEntry(0, 0);
652 endEntry = getMBBStartIdx(nextMBB).listEntry();
653 newItr = indexList.insert(endEntry, startEntry);
656 SlotIndex startIdx(startEntry, SlotIndex::Slot_Block);
657 SlotIndex endIdx(endEntry, SlotIndex::Slot_Block);
659 MachineFunction::iterator prevMBB(mbb);
660 assert(prevMBB != mbb->getParent()->end() &&
661 "Can't insert a new block at the beginning of a function.");
663 MBBRanges[prevMBB->getNumber()].second = startIdx;
665 assert(unsigned(mbb->getNumber()) == MBBRanges.size() &&
666 "Blocks must be added in order");
667 MBBRanges.push_back(std::make_pair(startIdx, endIdx));
668 idx2MBBMap.push_back(IdxMBBPair(startIdx, mbb));
670 renumberIndexes(newItr);
671 std::sort(idx2MBBMap.begin(), idx2MBBMap.end(), Idx2MBBCompare());
674 /// \brief Free the resources that were required to maintain a SlotIndex.
676 /// Once an index is no longer needed (for instance because the instruction
677 /// at that index has been moved), the resources required to maintain the
678 /// index can be relinquished to reduce memory use and improve renumbering
679 /// performance. Any remaining SlotIndex objects that point to the same
680 /// index are left 'dangling' (much the same as a dangling pointer to a
681 /// freed object) and should not be accessed, except to destruct them.
683 /// Like dangling pointers, access to dangling SlotIndexes can cause
684 /// painful-to-track-down bugs, especially if the memory for the index
685 /// previously pointed to has been re-used. To detect dangling SlotIndex
686 /// bugs, build with EXPENSIVE_CHECKS=1. This will cause "erased" indexes to
687 /// be retained in a graveyard instead of being freed. Operations on indexes
688 /// in the graveyard will trigger an assertion.
689 void eraseIndex(SlotIndex index) {
690 IndexListEntry *entry = index.listEntry();
691 #ifdef EXPENSIVE_CHECKS
692 indexList.remove(entry);
693 graveyardList.push_back(entry);
696 indexList.erase(entry);
703 // Specialize IntervalMapInfo for half-open slot index intervals.
705 struct IntervalMapInfo<SlotIndex> : IntervalMapHalfOpenInfo<SlotIndex> {
710 #endif // LLVM_CODEGEN_SLOTINDEXES_H