1//===-- LiveInterval.cpp - Live Interval Representation -------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements the LiveRange and LiveInterval classes. Given some 11// numbering of each the machine instructions an interval [i, j) is said to be a 12// live interval for register v if there is no instruction with number j' > j 13// such that v is live at j' and there is no instruction with number i' < i such 14// that v is live at i'. In this implementation intervals can have holes, 15// i.e. an interval might look like [1,20), [50,65), [1000,1001). Each 16// individual range is represented as an instance of LiveRange, and the whole 17// interval is represented as an instance of LiveInterval. 18// 19//===----------------------------------------------------------------------===// 20 21#include "llvm/CodeGen/LiveInterval.h" 22#include "llvm/CodeGen/LiveIntervalAnalysis.h" 23#include "llvm/CodeGen/MachineRegisterInfo.h" 24#include "llvm/ADT/DenseMap.h" 25#include "llvm/ADT/SmallSet.h" 26#include "llvm/ADT/STLExtras.h" 27#include "llvm/Support/Debug.h" 28#include "llvm/Support/raw_ostream.h" 29#include "llvm/Target/TargetRegisterInfo.h" 30#include "RegisterCoalescer.h" 31#include <algorithm> 32using namespace llvm; 33 34LiveInterval::iterator LiveInterval::find(SlotIndex Pos) { 35 // This algorithm is basically std::upper_bound. 36 // Unfortunately, std::upper_bound cannot be used with mixed types until we 37 // adopt C++0x. Many libraries can do it, but not all. 38 if (empty() || Pos >= endIndex()) 39 return end(); 40 iterator I = begin(); 41 size_t Len = ranges.size(); 42 do { 43 size_t Mid = Len >> 1; 44 if (Pos < I[Mid].end) 45 Len = Mid; 46 else 47 I += Mid + 1, Len -= Mid + 1; 48 } while (Len); 49 return I; 50} 51 52VNInfo *LiveInterval::createDeadDef(SlotIndex Def, 53 VNInfo::Allocator &VNInfoAllocator) { 54 assert(!Def.isDead() && "Cannot define a value at the dead slot"); 55 iterator I = find(Def); 56 if (I == end()) { 57 VNInfo *VNI = getNextValue(Def, VNInfoAllocator); 58 ranges.push_back(LiveRange(Def, Def.getDeadSlot(), VNI)); 59 return VNI; 60 } 61 if (SlotIndex::isSameInstr(Def, I->start)) { 62 assert(I->start == Def && "Cannot insert def, already live"); 63 assert(I->valno->def == Def && "Inconsistent existing value def"); 64 return I->valno; 65 } 66 assert(SlotIndex::isEarlierInstr(Def, I->start) && "Already live at def"); 67 VNInfo *VNI = getNextValue(Def, VNInfoAllocator); 68 ranges.insert(I, LiveRange(Def, Def.getDeadSlot(), VNI)); 69 return VNI; 70} 71 72// overlaps - Return true if the intersection of the two live intervals is 73// not empty. 74// 75// An example for overlaps(): 76// 77// 0: A = ... 78// 4: B = ... 79// 8: C = A + B ;; last use of A 80// 81// The live intervals should look like: 82// 83// A = [3, 11) 84// B = [7, x) 85// C = [11, y) 86// 87// A->overlaps(C) should return false since we want to be able to join 88// A and C. 89// 90bool LiveInterval::overlapsFrom(const LiveInterval& other, 91 const_iterator StartPos) const { 92 assert(!empty() && "empty interval"); 93 const_iterator i = begin(); 94 const_iterator ie = end(); 95 const_iterator j = StartPos; 96 const_iterator je = other.end(); 97 98 assert((StartPos->start <= i->start || StartPos == other.begin()) && 99 StartPos != other.end() && "Bogus start position hint!"); 100 101 if (i->start < j->start) { 102 i = std::upper_bound(i, ie, j->start); 103 if (i != ranges.begin()) --i; 104 } else if (j->start < i->start) { 105 ++StartPos; 106 if (StartPos != other.end() && StartPos->start <= i->start) { 107 assert(StartPos < other.end() && i < end()); 108 j = std::upper_bound(j, je, i->start); 109 if (j != other.ranges.begin()) --j; 110 } 111 } else { 112 return true; 113 } 114 115 if (j == je) return false; 116 117 while (i != ie) { 118 if (i->start > j->start) { 119 std::swap(i, j); 120 std::swap(ie, je); 121 } 122 123 if (i->end > j->start) 124 return true; 125 ++i; 126 } 127 128 return false; 129} 130 131bool LiveInterval::overlaps(const LiveInterval &Other, 132 const CoalescerPair &CP, 133 const SlotIndexes &Indexes) const { 134 assert(!empty() && "empty interval"); 135 if (Other.empty()) 136 return false; 137 138 // Use binary searches to find initial positions. 139 const_iterator I = find(Other.beginIndex()); 140 const_iterator IE = end(); 141 if (I == IE) 142 return false; 143 const_iterator J = Other.find(I->start); 144 const_iterator JE = Other.end(); 145 if (J == JE) 146 return false; 147 148 for (;;) { 149 // J has just been advanced to satisfy: 150 assert(J->end >= I->start); 151 // Check for an overlap. 152 if (J->start < I->end) { 153 // I and J are overlapping. Find the later start. 154 SlotIndex Def = std::max(I->start, J->start); 155 // Allow the overlap if Def is a coalescable copy. 156 if (Def.isBlock() || 157 !CP.isCoalescable(Indexes.getInstructionFromIndex(Def))) 158 return true; 159 } 160 // Advance the iterator that ends first to check for more overlaps. 161 if (J->end > I->end) { 162 std::swap(I, J); 163 std::swap(IE, JE); 164 } 165 // Advance J until J->end >= I->start. 166 do 167 if (++J == JE) 168 return false; 169 while (J->end < I->start); 170 } 171} 172 173/// overlaps - Return true if the live interval overlaps a range specified 174/// by [Start, End). 175bool LiveInterval::overlaps(SlotIndex Start, SlotIndex End) const { 176 assert(Start < End && "Invalid range"); 177 const_iterator I = std::lower_bound(begin(), end(), End); 178 return I != begin() && (--I)->end > Start; 179} 180 181 182/// ValNo is dead, remove it. If it is the largest value number, just nuke it 183/// (and any other deleted values neighboring it), otherwise mark it as ~1U so 184/// it can be nuked later. 185void LiveInterval::markValNoForDeletion(VNInfo *ValNo) { 186 if (ValNo->id == getNumValNums()-1) { 187 do { 188 valnos.pop_back(); 189 } while (!valnos.empty() && valnos.back()->isUnused()); 190 } else { 191 ValNo->markUnused(); 192 } 193} 194 195/// RenumberValues - Renumber all values in order of appearance and delete the 196/// remaining unused values. 197void LiveInterval::RenumberValues(LiveIntervals &lis) { 198 SmallPtrSet<VNInfo*, 8> Seen; 199 valnos.clear(); 200 for (const_iterator I = begin(), E = end(); I != E; ++I) { 201 VNInfo *VNI = I->valno; 202 if (!Seen.insert(VNI)) 203 continue; 204 assert(!VNI->isUnused() && "Unused valno used by live range"); 205 VNI->id = (unsigned)valnos.size(); 206 valnos.push_back(VNI); 207 } 208} 209 210/// extendIntervalEndTo - This method is used when we want to extend the range 211/// specified by I to end at the specified endpoint. To do this, we should 212/// merge and eliminate all ranges that this will overlap with. The iterator is 213/// not invalidated. 214void LiveInterval::extendIntervalEndTo(Ranges::iterator I, SlotIndex NewEnd) { 215 assert(I != ranges.end() && "Not a valid interval!"); 216 VNInfo *ValNo = I->valno; 217 218 // Search for the first interval that we can't merge with. 219 Ranges::iterator MergeTo = llvm::next(I); 220 for (; MergeTo != ranges.end() && NewEnd >= MergeTo->end; ++MergeTo) { 221 assert(MergeTo->valno == ValNo && "Cannot merge with differing values!"); 222 } 223 224 // If NewEnd was in the middle of an interval, make sure to get its endpoint. 225 I->end = std::max(NewEnd, prior(MergeTo)->end); 226 227 // If the newly formed range now touches the range after it and if they have 228 // the same value number, merge the two ranges into one range. 229 if (MergeTo != ranges.end() && MergeTo->start <= I->end && 230 MergeTo->valno == ValNo) { 231 I->end = MergeTo->end; 232 ++MergeTo; 233 } 234 235 // Erase any dead ranges. 236 ranges.erase(llvm::next(I), MergeTo); 237} 238 239 240/// extendIntervalStartTo - This method is used when we want to extend the range 241/// specified by I to start at the specified endpoint. To do this, we should 242/// merge and eliminate all ranges that this will overlap with. 243LiveInterval::Ranges::iterator 244LiveInterval::extendIntervalStartTo(Ranges::iterator I, SlotIndex NewStart) { 245 assert(I != ranges.end() && "Not a valid interval!"); 246 VNInfo *ValNo = I->valno; 247 248 // Search for the first interval that we can't merge with. 249 Ranges::iterator MergeTo = I; 250 do { 251 if (MergeTo == ranges.begin()) { 252 I->start = NewStart; 253 ranges.erase(MergeTo, I); 254 return I; 255 } 256 assert(MergeTo->valno == ValNo && "Cannot merge with differing values!"); 257 --MergeTo; 258 } while (NewStart <= MergeTo->start); 259 260 // If we start in the middle of another interval, just delete a range and 261 // extend that interval. 262 if (MergeTo->end >= NewStart && MergeTo->valno == ValNo) { 263 MergeTo->end = I->end; 264 } else { 265 // Otherwise, extend the interval right after. 266 ++MergeTo; 267 MergeTo->start = NewStart; 268 MergeTo->end = I->end; 269 } 270 271 ranges.erase(llvm::next(MergeTo), llvm::next(I)); 272 return MergeTo; 273} 274 275LiveInterval::iterator 276LiveInterval::addRangeFrom(LiveRange LR, iterator From) { 277 SlotIndex Start = LR.start, End = LR.end; 278 iterator it = std::upper_bound(From, ranges.end(), Start); 279 280 // If the inserted interval starts in the middle or right at the end of 281 // another interval, just extend that interval to contain the range of LR. 282 if (it != ranges.begin()) { 283 iterator B = prior(it); 284 if (LR.valno == B->valno) { 285 if (B->start <= Start && B->end >= Start) { 286 extendIntervalEndTo(B, End); 287 return B; 288 } 289 } else { 290 // Check to make sure that we are not overlapping two live ranges with 291 // different valno's. 292 assert(B->end <= Start && 293 "Cannot overlap two LiveRanges with differing ValID's" 294 " (did you def the same reg twice in a MachineInstr?)"); 295 } 296 } 297 298 // Otherwise, if this range ends in the middle of, or right next to, another 299 // interval, merge it into that interval. 300 if (it != ranges.end()) { 301 if (LR.valno == it->valno) { 302 if (it->start <= End) { 303 it = extendIntervalStartTo(it, Start); 304 305 // If LR is a complete superset of an interval, we may need to grow its 306 // endpoint as well. 307 if (End > it->end) 308 extendIntervalEndTo(it, End); 309 return it; 310 } 311 } else { 312 // Check to make sure that we are not overlapping two live ranges with 313 // different valno's. 314 assert(it->start >= End && 315 "Cannot overlap two LiveRanges with differing ValID's"); 316 } 317 } 318 319 // Otherwise, this is just a new range that doesn't interact with anything. 320 // Insert it. 321 return ranges.insert(it, LR); 322} 323 324/// extendInBlock - If this interval is live before Kill in the basic 325/// block that starts at StartIdx, extend it to be live up to Kill and return 326/// the value. If there is no live range before Kill, return NULL. 327VNInfo *LiveInterval::extendInBlock(SlotIndex StartIdx, SlotIndex Kill) { 328 if (empty()) 329 return 0; 330 iterator I = std::upper_bound(begin(), end(), Kill.getPrevSlot()); 331 if (I == begin()) 332 return 0; 333 --I; 334 if (I->end <= StartIdx) 335 return 0; 336 if (I->end < Kill) 337 extendIntervalEndTo(I, Kill); 338 return I->valno; 339} 340 341/// removeRange - Remove the specified range from this interval. Note that 342/// the range must be in a single LiveRange in its entirety. 343void LiveInterval::removeRange(SlotIndex Start, SlotIndex End, 344 bool RemoveDeadValNo) { 345 // Find the LiveRange containing this span. 346 Ranges::iterator I = find(Start); 347 assert(I != ranges.end() && "Range is not in interval!"); 348 assert(I->containsRange(Start, End) && "Range is not entirely in interval!"); 349 350 // If the span we are removing is at the start of the LiveRange, adjust it. 351 VNInfo *ValNo = I->valno; 352 if (I->start == Start) { 353 if (I->end == End) { 354 if (RemoveDeadValNo) { 355 // Check if val# is dead. 356 bool isDead = true; 357 for (const_iterator II = begin(), EE = end(); II != EE; ++II) 358 if (II != I && II->valno == ValNo) { 359 isDead = false; 360 break; 361 } 362 if (isDead) { 363 // Now that ValNo is dead, remove it. 364 markValNoForDeletion(ValNo); 365 } 366 } 367 368 ranges.erase(I); // Removed the whole LiveRange. 369 } else 370 I->start = End; 371 return; 372 } 373 374 // Otherwise if the span we are removing is at the end of the LiveRange, 375 // adjust the other way. 376 if (I->end == End) { 377 I->end = Start; 378 return; 379 } 380 381 // Otherwise, we are splitting the LiveRange into two pieces. 382 SlotIndex OldEnd = I->end; 383 I->end = Start; // Trim the old interval. 384 385 // Insert the new one. 386 ranges.insert(llvm::next(I), LiveRange(End, OldEnd, ValNo)); 387} 388 389/// removeValNo - Remove all the ranges defined by the specified value#. 390/// Also remove the value# from value# list. 391void LiveInterval::removeValNo(VNInfo *ValNo) { 392 if (empty()) return; 393 Ranges::iterator I = ranges.end(); 394 Ranges::iterator E = ranges.begin(); 395 do { 396 --I; 397 if (I->valno == ValNo) 398 ranges.erase(I); 399 } while (I != E); 400 // Now that ValNo is dead, remove it. 401 markValNoForDeletion(ValNo); 402} 403 404/// join - Join two live intervals (this, and other) together. This applies 405/// mappings to the value numbers in the LHS/RHS intervals as specified. If 406/// the intervals are not joinable, this aborts. 407void LiveInterval::join(LiveInterval &Other, 408 const int *LHSValNoAssignments, 409 const int *RHSValNoAssignments, 410 SmallVector<VNInfo*, 16> &NewVNInfo, 411 MachineRegisterInfo *MRI) { 412 verify(); 413 414 // Determine if any of our live range values are mapped. This is uncommon, so 415 // we want to avoid the interval scan if not. 416 bool MustMapCurValNos = false; 417 unsigned NumVals = getNumValNums(); 418 unsigned NumNewVals = NewVNInfo.size(); 419 for (unsigned i = 0; i != NumVals; ++i) { 420 unsigned LHSValID = LHSValNoAssignments[i]; 421 if (i != LHSValID || 422 (NewVNInfo[LHSValID] && NewVNInfo[LHSValID] != getValNumInfo(i))) { 423 MustMapCurValNos = true; 424 break; 425 } 426 } 427 428 // If we have to apply a mapping to our base interval assignment, rewrite it 429 // now. 430 if (MustMapCurValNos && !empty()) { 431 // Map the first live range. 432 433 iterator OutIt = begin(); 434 OutIt->valno = NewVNInfo[LHSValNoAssignments[OutIt->valno->id]]; 435 for (iterator I = next(OutIt), E = end(); I != E; ++I) { 436 VNInfo* nextValNo = NewVNInfo[LHSValNoAssignments[I->valno->id]]; 437 assert(nextValNo != 0 && "Huh?"); 438 439 // If this live range has the same value # as its immediate predecessor, 440 // and if they are neighbors, remove one LiveRange. This happens when we 441 // have [0,4:0)[4,7:1) and map 0/1 onto the same value #. 442 if (OutIt->valno == nextValNo && OutIt->end == I->start) { 443 OutIt->end = I->end; 444 } else { 445 // Didn't merge. Move OutIt to the next interval, 446 ++OutIt; 447 OutIt->valno = nextValNo; 448 if (OutIt != I) { 449 OutIt->start = I->start; 450 OutIt->end = I->end; 451 } 452 } 453 } 454 // If we merge some live ranges, chop off the end. 455 ++OutIt; 456 ranges.erase(OutIt, end()); 457 } 458 459 // Remember assignements because val# ids are changing. 460 SmallVector<unsigned, 16> OtherAssignments; 461 for (iterator I = Other.begin(), E = Other.end(); I != E; ++I) 462 OtherAssignments.push_back(RHSValNoAssignments[I->valno->id]); 463 464 // Update val# info. Renumber them and make sure they all belong to this 465 // LiveInterval now. Also remove dead val#'s. 466 unsigned NumValNos = 0; 467 for (unsigned i = 0; i < NumNewVals; ++i) { 468 VNInfo *VNI = NewVNInfo[i]; 469 if (VNI) { 470 if (NumValNos >= NumVals) 471 valnos.push_back(VNI); 472 else 473 valnos[NumValNos] = VNI; 474 VNI->id = NumValNos++; // Renumber val#. 475 } 476 } 477 if (NumNewVals < NumVals) 478 valnos.resize(NumNewVals); // shrinkify 479 480 // Okay, now insert the RHS live ranges into the LHS. 481 unsigned RangeNo = 0; 482 for (iterator I = Other.begin(), E = Other.end(); I != E; ++I, ++RangeNo) { 483 // Map the valno in the other live range to the current live range. 484 I->valno = NewVNInfo[OtherAssignments[RangeNo]]; 485 assert(I->valno && "Adding a dead range?"); 486 } 487 mergeIntervalRanges(Other); 488 489 verify(); 490} 491 492/// \brief Helper function for merging in another LiveInterval's ranges. 493/// 494/// This is a helper routine implementing an efficient merge of another 495/// LiveIntervals ranges into the current interval. 496/// 497/// \param LHSValNo If non-NULL, set as the new value number for every range 498/// from RHS which is merged into the LHS. 499/// \param RHSValNo If non-NULL, then only ranges in RHS whose original value 500/// number maches this value number will be merged into LHS. 501void LiveInterval::mergeIntervalRanges(const LiveInterval &RHS, 502 VNInfo *LHSValNo, 503 const VNInfo *RHSValNo) { 504 if (RHS.empty()) 505 return; 506 507 // Ensure we're starting with a valid range. Note that we don't verify RHS 508 // because it may have had its value numbers adjusted in preparation for 509 // merging. 510 verify(); 511 512 // The strategy for merging these efficiently is as follows: 513 // 514 // 1) Find the beginning of the impacted ranges in the LHS. 515 // 2) Create a new, merged sub-squence of ranges merging from the position in 516 // #1 until either LHS or RHS is exhausted. Any part of LHS between RHS 517 // entries being merged will be copied into this new range. 518 // 3) Replace the relevant section in LHS with these newly merged ranges. 519 // 4) Append any remaning ranges from RHS if LHS is exhausted in #2. 520 // 521 // We don't follow the typical in-place merge strategy for sorted ranges of 522 // appending the new ranges to the back and then using std::inplace_merge 523 // because one step of the merge can both mutate the original elements and 524 // remove elements from the original. Essentially, because the merge includes 525 // collapsing overlapping ranges, a more complex approach is required. 526 527 // We do an initial binary search to optimize for a common pattern: a large 528 // LHS, and a very small RHS. 529 const_iterator RI = RHS.begin(), RE = RHS.end(); 530 iterator LE = end(), LI = std::upper_bound(begin(), LE, *RI); 531 532 // Merge into NewRanges until one of the ranges is exhausted. 533 SmallVector<LiveRange, 4> NewRanges; 534 535 // Keep track of where to begin the replacement. 536 iterator ReplaceI = LI; 537 538 // If there are preceding ranges in the LHS, put the last one into NewRanges 539 // so we can optionally extend it. Adjust the replacement point accordingly. 540 if (LI != begin()) { 541 ReplaceI = llvm::prior(LI); 542 NewRanges.push_back(*ReplaceI); 543 } 544 545 // Now loop over the mergable portions of both LHS and RHS, merging into 546 // NewRanges. 547 while (LI != LE && RI != RE) { 548 // Skip incoming ranges with the wrong value. 549 if (RHSValNo && RI->valno != RHSValNo) { 550 ++RI; 551 continue; 552 } 553 554 // Select the first range. We pick the earliest start point, and then the 555 // largest range. 556 LiveRange R = *LI; 557 if (*RI < R) { 558 R = *RI; 559 ++RI; 560 if (LHSValNo) 561 R.valno = LHSValNo; 562 } else { 563 ++LI; 564 } 565 566 if (NewRanges.empty()) { 567 NewRanges.push_back(R); 568 continue; 569 } 570 571 LiveRange &LastR = NewRanges.back(); 572 if (R.valno == LastR.valno) { 573 // Try to merge this range into the last one. 574 if (R.start <= LastR.end) { 575 LastR.end = std::max(LastR.end, R.end); 576 continue; 577 } 578 } else { 579 // We can't merge ranges across a value number. 580 assert(R.start >= LastR.end && 581 "Cannot overlap two LiveRanges with differing ValID's"); 582 } 583 584 // If all else fails, just append the range. 585 NewRanges.push_back(R); 586 } 587 assert(RI == RE || LI == LE); 588 589 // Check for being able to merge into the trailing sequence of ranges on the LHS. 590 if (!NewRanges.empty()) 591 for (; LI != LE && (LI->valno == NewRanges.back().valno && 592 LI->start <= NewRanges.back().end); 593 ++LI) 594 NewRanges.back().end = std::max(NewRanges.back().end, LI->end); 595 596 // Replace the ranges in the LHS with the newly merged ones. It would be 597 // really nice if there were a move-supporting 'replace' directly in 598 // SmallVector, but as there is not, we pay the price of copies to avoid 599 // wasted memory allocations. 600 SmallVectorImpl<LiveRange>::iterator NRI = NewRanges.begin(), 601 NRE = NewRanges.end(); 602 for (; ReplaceI != LI && NRI != NRE; ++ReplaceI, ++NRI) 603 *ReplaceI = *NRI; 604 if (NRI == NRE) 605 ranges.erase(ReplaceI, LI); 606 else 607 ranges.insert(LI, NRI, NRE); 608 609 // And finally insert any trailing end of RHS (if we have one). 610 for (; RI != RE; ++RI) { 611 LiveRange R = *RI; 612 if (LHSValNo) 613 R.valno = LHSValNo; 614 if (!ranges.empty() && 615 ranges.back().valno == R.valno && R.start <= ranges.back().end) 616 ranges.back().end = std::max(ranges.back().end, R.end); 617 else 618 ranges.push_back(R); 619 } 620 621 // Ensure we finished with a valid new sequence of ranges. 622 verify(); 623} 624 625/// MergeRangesInAsValue - Merge all of the intervals in RHS into this live 626/// interval as the specified value number. The LiveRanges in RHS are 627/// allowed to overlap with LiveRanges in the current interval, but only if 628/// the overlapping LiveRanges have the specified value number. 629void LiveInterval::MergeRangesInAsValue(const LiveInterval &RHS, 630 VNInfo *LHSValNo) { 631 mergeIntervalRanges(RHS, LHSValNo); 632} 633 634/// MergeValueInAsValue - Merge all of the live ranges of a specific val# 635/// in RHS into this live interval as the specified value number. 636/// The LiveRanges in RHS are allowed to overlap with LiveRanges in the 637/// current interval, it will replace the value numbers of the overlaped 638/// live ranges with the specified value number. 639void LiveInterval::MergeValueInAsValue(const LiveInterval &RHS, 640 const VNInfo *RHSValNo, 641 VNInfo *LHSValNo) { 642 mergeIntervalRanges(RHS, LHSValNo, RHSValNo); 643} 644 645/// MergeValueNumberInto - This method is called when two value nubmers 646/// are found to be equivalent. This eliminates V1, replacing all 647/// LiveRanges with the V1 value number with the V2 value number. This can 648/// cause merging of V1/V2 values numbers and compaction of the value space. 649VNInfo* LiveInterval::MergeValueNumberInto(VNInfo *V1, VNInfo *V2) { 650 assert(V1 != V2 && "Identical value#'s are always equivalent!"); 651 652 // This code actually merges the (numerically) larger value number into the 653 // smaller value number, which is likely to allow us to compactify the value 654 // space. The only thing we have to be careful of is to preserve the 655 // instruction that defines the result value. 656 657 // Make sure V2 is smaller than V1. 658 if (V1->id < V2->id) { 659 V1->copyFrom(*V2); 660 std::swap(V1, V2); 661 } 662 663 // Merge V1 live ranges into V2. 664 for (iterator I = begin(); I != end(); ) { 665 iterator LR = I++; 666 if (LR->valno != V1) continue; // Not a V1 LiveRange. 667 668 // Okay, we found a V1 live range. If it had a previous, touching, V2 live 669 // range, extend it. 670 if (LR != begin()) { 671 iterator Prev = LR-1; 672 if (Prev->valno == V2 && Prev->end == LR->start) { 673 Prev->end = LR->end; 674 675 // Erase this live-range. 676 ranges.erase(LR); 677 I = Prev+1; 678 LR = Prev; 679 } 680 } 681 682 // Okay, now we have a V1 or V2 live range that is maximally merged forward. 683 // Ensure that it is a V2 live-range. 684 LR->valno = V2; 685 686 // If we can merge it into later V2 live ranges, do so now. We ignore any 687 // following V1 live ranges, as they will be merged in subsequent iterations 688 // of the loop. 689 if (I != end()) { 690 if (I->start == LR->end && I->valno == V2) { 691 LR->end = I->end; 692 ranges.erase(I); 693 I = LR+1; 694 } 695 } 696 } 697 698 // Now that V1 is dead, remove it. 699 markValNoForDeletion(V1); 700 701 return V2; 702} 703 704unsigned LiveInterval::getSize() const { 705 unsigned Sum = 0; 706 for (const_iterator I = begin(), E = end(); I != E; ++I) 707 Sum += I->start.distance(I->end); 708 return Sum; 709} 710 711raw_ostream& llvm::operator<<(raw_ostream& os, const LiveRange &LR) { 712 return os << '[' << LR.start << ',' << LR.end << ':' << LR.valno->id << ")"; 713} 714 715#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 716void LiveRange::dump() const { 717 dbgs() << *this << "\n"; 718} 719#endif 720 721void LiveInterval::print(raw_ostream &OS) const { 722 if (empty()) 723 OS << "EMPTY"; 724 else { 725 for (LiveInterval::Ranges::const_iterator I = ranges.begin(), 726 E = ranges.end(); I != E; ++I) { 727 OS << *I; 728 assert(I->valno == getValNumInfo(I->valno->id) && "Bad VNInfo"); 729 } 730 } 731 732 // Print value number info. 733 if (getNumValNums()) { 734 OS << " "; 735 unsigned vnum = 0; 736 for (const_vni_iterator i = vni_begin(), e = vni_end(); i != e; 737 ++i, ++vnum) { 738 const VNInfo *vni = *i; 739 if (vnum) OS << " "; 740 OS << vnum << "@"; 741 if (vni->isUnused()) { 742 OS << "x"; 743 } else { 744 OS << vni->def; 745 if (vni->isPHIDef()) 746 OS << "-phi"; 747 } 748 } 749 } 750} 751 752#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 753void LiveInterval::dump() const { 754 dbgs() << *this << "\n"; 755} 756#endif 757 758#ifndef NDEBUG 759void LiveInterval::verify() const { 760 for (const_iterator I = begin(), E = end(); I != E; ++I) { 761 assert(I->start.isValid()); 762 assert(I->end.isValid()); 763 assert(I->start < I->end); 764 assert(I->valno != 0); 765 assert(I->valno == valnos[I->valno->id]); 766 if (llvm::next(I) != E) { 767 assert(I->end <= llvm::next(I)->start); 768 if (I->end == llvm::next(I)->start) 769 assert(I->valno != llvm::next(I)->valno); 770 } 771 } 772} 773#endif 774 775 776void LiveRange::print(raw_ostream &os) const { 777 os << *this; 778} 779 780unsigned ConnectedVNInfoEqClasses::Classify(const LiveInterval *LI) { 781 // Create initial equivalence classes. 782 EqClass.clear(); 783 EqClass.grow(LI->getNumValNums()); 784 785 const VNInfo *used = 0, *unused = 0; 786 787 // Determine connections. 788 for (LiveInterval::const_vni_iterator I = LI->vni_begin(), E = LI->vni_end(); 789 I != E; ++I) { 790 const VNInfo *VNI = *I; 791 // Group all unused values into one class. 792 if (VNI->isUnused()) { 793 if (unused) 794 EqClass.join(unused->id, VNI->id); 795 unused = VNI; 796 continue; 797 } 798 used = VNI; 799 if (VNI->isPHIDef()) { 800 const MachineBasicBlock *MBB = LIS.getMBBFromIndex(VNI->def); 801 assert(MBB && "Phi-def has no defining MBB"); 802 // Connect to values live out of predecessors. 803 for (MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(), 804 PE = MBB->pred_end(); PI != PE; ++PI) 805 if (const VNInfo *PVNI = LI->getVNInfoBefore(LIS.getMBBEndIdx(*PI))) 806 EqClass.join(VNI->id, PVNI->id); 807 } else { 808 // Normal value defined by an instruction. Check for two-addr redef. 809 // FIXME: This could be coincidental. Should we really check for a tied 810 // operand constraint? 811 // Note that VNI->def may be a use slot for an early clobber def. 812 if (const VNInfo *UVNI = LI->getVNInfoBefore(VNI->def)) 813 EqClass.join(VNI->id, UVNI->id); 814 } 815 } 816 817 // Lump all the unused values in with the last used value. 818 if (used && unused) 819 EqClass.join(used->id, unused->id); 820 821 EqClass.compress(); 822 return EqClass.getNumClasses(); 823} 824 825void ConnectedVNInfoEqClasses::Distribute(LiveInterval *LIV[], 826 MachineRegisterInfo &MRI) { 827 assert(LIV[0] && "LIV[0] must be set"); 828 LiveInterval &LI = *LIV[0]; 829 830 // Rewrite instructions. 831 for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(LI.reg), 832 RE = MRI.reg_end(); RI != RE;) { 833 MachineOperand &MO = RI.getOperand(); 834 MachineInstr *MI = MO.getParent(); 835 ++RI; 836 // DBG_VALUE instructions should have been eliminated earlier. 837 LiveRangeQuery LRQ(LI, LIS.getInstructionIndex(MI)); 838 const VNInfo *VNI = MO.readsReg() ? LRQ.valueIn() : LRQ.valueDefined(); 839 // In the case of an <undef> use that isn't tied to any def, VNI will be 840 // NULL. If the use is tied to a def, VNI will be the defined value. 841 if (!VNI) 842 continue; 843 MO.setReg(LIV[getEqClass(VNI)]->reg); 844 } 845 846 // Move runs to new intervals. 847 LiveInterval::iterator J = LI.begin(), E = LI.end(); 848 while (J != E && EqClass[J->valno->id] == 0) 849 ++J; 850 for (LiveInterval::iterator I = J; I != E; ++I) { 851 if (unsigned eq = EqClass[I->valno->id]) { 852 assert((LIV[eq]->empty() || LIV[eq]->expiredAt(I->start)) && 853 "New intervals should be empty"); 854 LIV[eq]->ranges.push_back(*I); 855 } else 856 *J++ = *I; 857 } 858 LI.ranges.erase(J, E); 859 860 // Transfer VNInfos to their new owners and renumber them. 861 unsigned j = 0, e = LI.getNumValNums(); 862 while (j != e && EqClass[j] == 0) 863 ++j; 864 for (unsigned i = j; i != e; ++i) { 865 VNInfo *VNI = LI.getValNumInfo(i); 866 if (unsigned eq = EqClass[i]) { 867 VNI->id = LIV[eq]->getNumValNums(); 868 LIV[eq]->valnos.push_back(VNI); 869 } else { 870 VNI->id = j; 871 LI.valnos[j++] = VNI; 872 } 873 } 874 LI.valnos.resize(j); 875} 876