lib/CodeGen/LiveInterval.cpp

   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 <algorithm>
  31 using namespace llvm;
  32
  33 // CompEnd - Compare LiveRange ends.
  34 namespace {
  35 struct CompEnd {
  36   bool operator()(const LiveRange &A, const LiveRange &B) const {
  37     return A.end < B.end;
  38   }
  39 };
  40 }
  41
  42 LiveInterval::iterator LiveInterval::find(SlotIndex Pos) {
  43   assert(Pos.isValid() && "Cannot search for an invalid index");
  44   return std::upper_bound(begin(), end(), LiveRange(SlotIndex(), Pos, 0),
  45                           CompEnd());
  46 }
  47
  48 /// killedInRange - Return true if the interval has kills in [Start,End).
  49 bool LiveInterval::killedInRange(SlotIndex Start, SlotIndex End) const {
  50   Ranges::const_iterator r =
  51     std::lower_bound(ranges.begin(), ranges.end(), End);
  52
  53   // Now r points to the first interval with start >= End, or ranges.end().
  54   if (r == ranges.begin())
  55     return false;
  56
  57   --r;
  58   // Now r points to the last interval with end <= End.
  59   // r->end is the kill point.
  60   return r->end >= Start && r->end < End;
  61 }
  62
  63 // overlaps - Return true if the intersection of the two live intervals is
  64 // not empty.
  65 //
  66 // An example for overlaps():
  67 //
  68 // 0: A = ...
  69 // 4: B = ...
  70 // 8: C = A + B ;; last use of A
  71 //
  72 // The live intervals should look like:
  73 //
  74 // A = [3, 11)
  75 // B = [7, x)
  76 // C = [11, y)
  77 //
  78 // A->overlaps(C) should return false since we want to be able to join
  79 // A and C.
  80 //
  81 bool LiveInterval::overlapsFrom(const LiveInterval& other,
  82                                 const_iterator StartPos) const {
  83   assert(!empty() && "empty interval");
  84   const_iterator i = begin();
  85   const_iterator ie = end();
  86   const_iterator j = StartPos;
  87   const_iterator je = other.end();
  88
  89   assert((StartPos->start <= i->start || StartPos == other.begin()) &&
  90          StartPos != other.end() && "Bogus start position hint!");
  91
  92   if (i->start < j->start) {
  93     i = std::upper_bound(i, ie, j->start);
  94     if (i != ranges.begin()) --i;
  95   } else if (j->start < i->start) {
  96     ++StartPos;
  97     if (StartPos != other.end() && StartPos->start <= i->start) {
  98       assert(StartPos < other.end() && i < end());
  99       j = std::upper_bound(j, je, i->start);
 100       if (j != other.ranges.begin()) --j;
 101     }
 102   } else {
 103     return true;
 104   }
 105
 106   if (j == je) return false;
 107
 108   while (i != ie) {
 109     if (i->start > j->start) {
 110       std::swap(i, j);
 111       std::swap(ie, je);
 112     }
 113
 114     if (i->end > j->start)
 115       return true;
 116     ++i;
 117   }
 118
 119   return false;
 120 }
 121
 122 /// overlaps - Return true if the live interval overlaps a range specified
 123 /// by [Start, End).
 124 bool LiveInterval::overlaps(SlotIndex Start, SlotIndex End) const {
 125   assert(Start < End && "Invalid range");
 126   const_iterator I = std::lower_bound(begin(), end(), End);
 127   return I != begin() && (--I)->end > Start;
 128 }
 129
 130
 131 /// ValNo is dead, remove it.  If it is the largest value number, just nuke it
 132 /// (and any other deleted values neighboring it), otherwise mark it as ~1U so
 133 /// it can be nuked later.
 134 void LiveInterval::markValNoForDeletion(VNInfo *ValNo) {
 135   if (ValNo->id == getNumValNums()-1) {
 136     do {
 137       valnos.pop_back();
 138     } while (!valnos.empty() && valnos.back()->isUnused());
 139   } else {
 140     ValNo->setIsUnused(true);
 141   }
 142 }
 143
 144 /// RenumberValues - Renumber all values in order of appearance and delete the
 145 /// remaining unused values.
 146 void LiveInterval::RenumberValues(LiveIntervals &lis) {
 147   SmallPtrSet<VNInfo*, 8> Seen;
 148   bool seenPHIDef = false;
 149   valnos.clear();
 150   for (const_iterator I = begin(), E = end(); I != E; ++I) {
 151     VNInfo *VNI = I->valno;
 152     if (!Seen.insert(VNI))
 153       continue;
 154     assert(!VNI->isUnused() && "Unused valno used by live range");
 155     VNI->id = (unsigned)valnos.size();
 156     valnos.push_back(VNI);
 157     VNI->setHasPHIKill(false);
 158     if (VNI->isPHIDef())
 159       seenPHIDef = true;
 160   }
 161
 162   // Recompute phi kill flags.
 163   if (!seenPHIDef)
 164     return;
 165   for (const_vni_iterator I = vni_begin(), E = vni_end(); I != E; ++I) {
 166     VNInfo *VNI = *I;
 167     if (!VNI->isPHIDef())
 168       continue;
 169     const MachineBasicBlock *PHIBB = lis.getMBBFromIndex(VNI->def);
 170     assert(PHIBB && "No basic block for phi-def");
 171     for (MachineBasicBlock::const_pred_iterator PI = PHIBB->pred_begin(),
 172          PE = PHIBB->pred_end(); PI != PE; ++PI) {
 173       VNInfo *KVNI = getVNInfoAt(lis.getMBBEndIdx(*PI).getPrevSlot());
 174       if (KVNI)
 175         KVNI->setHasPHIKill(true);
 176     }
 177   }
 178 }
 179
 180 /// extendIntervalEndTo - This method is used when we want to extend the range
 181 /// specified by I to end at the specified endpoint.  To do this, we should
 182 /// merge and eliminate all ranges that this will overlap with.  The iterator is
 183 /// not invalidated.
 184 void LiveInterval::extendIntervalEndTo(Ranges::iterator I, SlotIndex NewEnd) {
 185   assert(I != ranges.end() && "Not a valid interval!");
 186   VNInfo *ValNo = I->valno;
 187
 188   // Search for the first interval that we can't merge with.
 189   Ranges::iterator MergeTo = llvm::next(I);
 190   for (; MergeTo != ranges.end() && NewEnd >= MergeTo->end; ++MergeTo) {
 191     assert(MergeTo->valno == ValNo && "Cannot merge with differing values!");
 192   }
 193
 194   // If NewEnd was in the middle of an interval, make sure to get its endpoint.
 195   I->end = std::max(NewEnd, prior(MergeTo)->end);
 196
 197   // Erase any dead ranges.
 198   ranges.erase(llvm::next(I), MergeTo);
 199
 200   // If the newly formed range now touches the range after it and if they have
 201   // the same value number, merge the two ranges into one range.
 202   Ranges::iterator Next = llvm::next(I);
 203   if (Next != ranges.end() && Next->start <= I->end && Next->valno == ValNo) {
 204     I->end = Next->end;
 205     ranges.erase(Next);
 206   }
 207 }
 208
 209
 210 /// extendIntervalStartTo - This method is used when we want to extend the range
 211 /// specified by I to start at the specified endpoint.  To do this, we should
 212 /// merge and eliminate all ranges that this will overlap with.
 213 LiveInterval::Ranges::iterator
 214 LiveInterval::extendIntervalStartTo(Ranges::iterator I, SlotIndex NewStart) {
 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 = I;
 220   do {
 221     if (MergeTo == ranges.begin()) {
 222       I->start = NewStart;
 223       ranges.erase(MergeTo, I);
 224       return I;
 225     }
 226     assert(MergeTo->valno == ValNo && "Cannot merge with differing values!");
 227     --MergeTo;
 228   } while (NewStart <= MergeTo->start);
 229
 230   // If we start in the middle of another interval, just delete a range and
 231   // extend that interval.
 232   if (MergeTo->end >= NewStart && MergeTo->valno == ValNo) {
 233     MergeTo->end = I->end;
 234   } else {
 235     // Otherwise, extend the interval right after.
 236     ++MergeTo;
 237     MergeTo->start = NewStart;
 238     MergeTo->end = I->end;
 239   }
 240
 241   ranges.erase(llvm::next(MergeTo), llvm::next(I));
 242   return MergeTo;
 243 }
 244
 245 LiveInterval::iterator
 246 LiveInterval::addRangeFrom(LiveRange LR, iterator From) {
 247   SlotIndex Start = LR.start, End = LR.end;
 248   iterator it = std::upper_bound(From, ranges.end(), Start);
 249
 250   // If the inserted interval starts in the middle or right at the end of
 251   // another interval, just extend that interval to contain the range of LR.
 252   if (it != ranges.begin()) {
 253     iterator B = prior(it);
 254     if (LR.valno == B->valno) {
 255       if (B->start <= Start && B->end >= Start) {
 256         extendIntervalEndTo(B, End);
 257         return B;
 258       }
 259     } else {
 260       // Check to make sure that we are not overlapping two live ranges with
 261       // different valno's.
 262       assert(B->end <= Start &&
 263              "Cannot overlap two LiveRanges with differing ValID's"
 264              " (did you def the same reg twice in a MachineInstr?)");
 265     }
 266   }
 267
 268   // Otherwise, if this range ends in the middle of, or right next to, another
 269   // interval, merge it into that interval.
 270   if (it != ranges.end()) {
 271     if (LR.valno == it->valno) {
 272       if (it->start <= End) {
 273         it = extendIntervalStartTo(it, Start);
 274
 275         // If LR is a complete superset of an interval, we may need to grow its
 276         // endpoint as well.
 277         if (End > it->end)
 278           extendIntervalEndTo(it, End);
 279         return it;
 280       }
 281     } else {
 282       // Check to make sure that we are not overlapping two live ranges with
 283       // different valno's.
 284       assert(it->start >= End &&
 285              "Cannot overlap two LiveRanges with differing ValID's");
 286     }
 287   }
 288
 289   // Otherwise, this is just a new range that doesn't interact with anything.
 290   // Insert it.
 291   return ranges.insert(it, LR);
 292 }
 293
 294
 295 /// removeRange - Remove the specified range from this interval.  Note that
 296 /// the range must be in a single LiveRange in its entirety.
 297 void LiveInterval::removeRange(SlotIndex Start, SlotIndex End,
 298                                bool RemoveDeadValNo) {
 299   // Find the LiveRange containing this span.
 300   Ranges::iterator I = find(Start);
 301   assert(I != ranges.end() && "Range is not in interval!");
 302   assert(I->containsRange(Start, End) && "Range is not entirely in interval!");
 303
 304   // If the span we are removing is at the start of the LiveRange, adjust it.
 305   VNInfo *ValNo = I->valno;
 306   if (I->start == Start) {
 307     if (I->end == End) {
 308       if (RemoveDeadValNo) {
 309         // Check if val# is dead.
 310         bool isDead = true;
 311         for (const_iterator II = begin(), EE = end(); II != EE; ++II)
 312           if (II != I && II->valno == ValNo) {
 313             isDead = false;
 314             break;
 315           }
 316         if (isDead) {
 317           // Now that ValNo is dead, remove it.
 318           markValNoForDeletion(ValNo);
 319         }
 320       }
 321
 322       ranges.erase(I);  // Removed the whole LiveRange.
 323     } else
 324       I->start = End;
 325     return;
 326   }
 327
 328   // Otherwise if the span we are removing is at the end of the LiveRange,
 329   // adjust the other way.
 330   if (I->end == End) {
 331     I->end = Start;
 332     return;
 333   }
 334
 335   // Otherwise, we are splitting the LiveRange into two pieces.
 336   SlotIndex OldEnd = I->end;
 337   I->end = Start;   // Trim the old interval.
 338
 339   // Insert the new one.
 340   ranges.insert(llvm::next(I), LiveRange(End, OldEnd, ValNo));
 341 }
 342
 343 /// removeValNo - Remove all the ranges defined by the specified value#.
 344 /// Also remove the value# from value# list.
 345 void LiveInterval::removeValNo(VNInfo *ValNo) {
 346   if (empty()) return;
 347   Ranges::iterator I = ranges.end();
 348   Ranges::iterator E = ranges.begin();
 349   do {
 350     --I;
 351     if (I->valno == ValNo)
 352       ranges.erase(I);
 353   } while (I != E);
 354   // Now that ValNo is dead, remove it.
 355   markValNoForDeletion(ValNo);
 356 }
 357
 358 /// findDefinedVNInfo - Find the VNInfo defined by the specified
 359 /// index (register interval).
 360 VNInfo *LiveInterval::findDefinedVNInfoForRegInt(SlotIndex Idx) const {
 361   for (LiveInterval::const_vni_iterator i = vni_begin(), e = vni_end();
 362        i != e; ++i) {
 363     if ((*i)->def == Idx)
 364       return *i;
 365   }
 366
 367   return 0;
 368 }
 369
 370 /// join - Join two live intervals (this, and other) together.  This applies
 371 /// mappings to the value numbers in the LHS/RHS intervals as specified.  If
 372 /// the intervals are not joinable, this aborts.
 373 void LiveInterval::join(LiveInterval &Other,
 374                         const int *LHSValNoAssignments,
 375                         const int *RHSValNoAssignments,
 376                         SmallVector<VNInfo*, 16> &NewVNInfo,
 377                         MachineRegisterInfo *MRI) {
 378   // Determine if any of our live range values are mapped.  This is uncommon, so
 379   // we want to avoid the interval scan if not.
 380   bool MustMapCurValNos = false;
 381   unsigned NumVals = getNumValNums();
 382   unsigned NumNewVals = NewVNInfo.size();
 383   for (unsigned i = 0; i != NumVals; ++i) {
 384     unsigned LHSValID = LHSValNoAssignments[i];
 385     if (i != LHSValID ||
 386         (NewVNInfo[LHSValID] && NewVNInfo[LHSValID] != getValNumInfo(i)))
 387       MustMapCurValNos = true;
 388   }
 389
 390   // If we have to apply a mapping to our base interval assignment, rewrite it
 391   // now.
 392   if (MustMapCurValNos) {
 393     // Map the first live range.
 394     iterator OutIt = begin();
 395     OutIt->valno = NewVNInfo[LHSValNoAssignments[OutIt->valno->id]];
 396     ++OutIt;
 397     for (iterator I = OutIt, E = end(); I != E; ++I) {
 398       OutIt->valno = NewVNInfo[LHSValNoAssignments[I->valno->id]];
 399
 400       // If this live range has the same value # as its immediate predecessor,
 401       // and if they are neighbors, remove one LiveRange.  This happens when we
 402       // have [0,3:0)[4,7:1) and map 0/1 onto the same value #.
 403       if (OutIt->valno == (OutIt-1)->valno && (OutIt-1)->end == OutIt->start) {
 404         (OutIt-1)->end = OutIt->end;
 405       } else {
 406         if (I != OutIt) {
 407           OutIt->start = I->start;
 408           OutIt->end = I->end;
 409         }
 410
 411         // Didn't merge, on to the next one.
 412         ++OutIt;
 413       }
 414     }
 415
 416     // If we merge some live ranges, chop off the end.
 417     ranges.erase(OutIt, end());
 418   }
 419
 420   // Remember assignements because val# ids are changing.
 421   SmallVector<unsigned, 16> OtherAssignments;
 422   for (iterator I = Other.begin(), E = Other.end(); I != E; ++I)
 423     OtherAssignments.push_back(RHSValNoAssignments[I->valno->id]);
 424
 425   // Update val# info. Renumber them and make sure they all belong to this
 426   // LiveInterval now. Also remove dead val#'s.
 427   unsigned NumValNos = 0;
 428   for (unsigned i = 0; i < NumNewVals; ++i) {
 429     VNInfo *VNI = NewVNInfo[i];
 430     if (VNI) {
 431       if (NumValNos >= NumVals)
 432         valnos.push_back(VNI);
 433       else
 434         valnos[NumValNos] = VNI;
 435       VNI->id = NumValNos++;  // Renumber val#.
 436     }
 437   }
 438   if (NumNewVals < NumVals)
 439     valnos.resize(NumNewVals);  // shrinkify
 440
 441   // Okay, now insert the RHS live ranges into the LHS.
 442   iterator InsertPos = begin();
 443   unsigned RangeNo = 0;
 444   for (iterator I = Other.begin(), E = Other.end(); I != E; ++I, ++RangeNo) {
 445     // Map the valno in the other live range to the current live range.
 446     I->valno = NewVNInfo[OtherAssignments[RangeNo]];
 447     assert(I->valno && "Adding a dead range?");
 448     InsertPos = addRangeFrom(*I, InsertPos);
 449   }
 450
 451   ComputeJoinedWeight(Other);
 452 }
 453
 454 /// MergeRangesInAsValue - Merge all of the intervals in RHS into this live
 455 /// interval as the specified value number.  The LiveRanges in RHS are
 456 /// allowed to overlap with LiveRanges in the current interval, but only if
 457 /// the overlapping LiveRanges have the specified value number.
 458 void LiveInterval::MergeRangesInAsValue(const LiveInterval &RHS,
 459                                         VNInfo *LHSValNo) {
 460   // TODO: Make this more efficient.
 461   iterator InsertPos = begin();
 462   for (const_iterator I = RHS.begin(), E = RHS.end(); I != E; ++I) {
 463     // Map the valno in the other live range to the current live range.
 464     LiveRange Tmp = *I;
 465     Tmp.valno = LHSValNo;
 466     InsertPos = addRangeFrom(Tmp, InsertPos);
 467   }
 468 }
 469
 470
 471 /// MergeValueInAsValue - Merge all of the live ranges of a specific val#
 472 /// in RHS into this live interval as the specified value number.
 473 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
 474 /// current interval, it will replace the value numbers of the overlaped
 475 /// live ranges with the specified value number.
 476 void LiveInterval::MergeValueInAsValue(
 477                                     const LiveInterval &RHS,
 478                                     const VNInfo *RHSValNo, VNInfo *LHSValNo) {
 479   SmallVector<VNInfo*, 4> ReplacedValNos;
 480   iterator IP = begin();
 481   for (const_iterator I = RHS.begin(), E = RHS.end(); I != E; ++I) {
 482     assert(I->valno == RHS.getValNumInfo(I->valno->id) && "Bad VNInfo");
 483     if (I->valno != RHSValNo)
 484       continue;
 485     SlotIndex Start = I->start, End = I->end;
 486     IP = std::upper_bound(IP, end(), Start);
 487     // If the start of this range overlaps with an existing liverange, trim it.
 488     if (IP != begin() && IP[-1].end > Start) {
 489       if (IP[-1].valno != LHSValNo) {
 490         ReplacedValNos.push_back(IP[-1].valno);
 491         IP[-1].valno = LHSValNo; // Update val#.
 492       }
 493       Start = IP[-1].end;
 494       // Trimmed away the whole range?
 495       if (Start >= End) continue;
 496     }
 497     // If the end of this range overlaps with an existing liverange, trim it.
 498     if (IP != end() && End > IP->start) {
 499       if (IP->valno != LHSValNo) {
 500         ReplacedValNos.push_back(IP->valno);
 501         IP->valno = LHSValNo;  // Update val#.
 502       }
 503       End = IP->start;
 504       // If this trimmed away the whole range, ignore it.
 505       if (Start == End) continue;
 506     }
 507
 508     // Map the valno in the other live range to the current live range.
 509     IP = addRangeFrom(LiveRange(Start, End, LHSValNo), IP);
 510   }
 511
 512
 513   SmallSet<VNInfo*, 4> Seen;
 514   for (unsigned i = 0, e = ReplacedValNos.size(); i != e; ++i) {
 515     VNInfo *V1 = ReplacedValNos[i];
 516     if (Seen.insert(V1)) {
 517       bool isDead = true;
 518       for (const_iterator I = begin(), E = end(); I != E; ++I)
 519         if (I->valno == V1) {
 520           isDead = false;
 521           break;
 522         }
 523       if (isDead) {
 524         // Now that V1 is dead, remove it.
 525         markValNoForDeletion(V1);
 526       }
 527     }
 528   }
 529 }
 530
 531
 532
 533 /// MergeValueNumberInto - This method is called when two value nubmers
 534 /// are found to be equivalent.  This eliminates V1, replacing all
 535 /// LiveRanges with the V1 value number with the V2 value number.  This can
 536 /// cause merging of V1/V2 values numbers and compaction of the value space.
 537 VNInfo* LiveInterval::MergeValueNumberInto(VNInfo *V1, VNInfo *V2) {
 538   assert(V1 != V2 && "Identical value#'s are always equivalent!");
 539
 540   // This code actually merges the (numerically) larger value number into the
 541   // smaller value number, which is likely to allow us to compactify the value
 542   // space.  The only thing we have to be careful of is to preserve the
 543   // instruction that defines the result value.
 544
 545   // Make sure V2 is smaller than V1.
 546   if (V1->id < V2->id) {
 547     V1->copyFrom(*V2);
 548     std::swap(V1, V2);
 549   }
 550
 551   // Merge V1 live ranges into V2.
 552   for (iterator I = begin(); I != end(); ) {
 553     iterator LR = I++;
 554     if (LR->valno != V1) continue;  // Not a V1 LiveRange.
 555
 556     // Okay, we found a V1 live range.  If it had a previous, touching, V2 live
 557     // range, extend it.
 558     if (LR != begin()) {
 559       iterator Prev = LR-1;
 560       if (Prev->valno == V2 && Prev->end == LR->start) {
 561         Prev->end = LR->end;
 562
 563         // Erase this live-range.
 564         ranges.erase(LR);
 565         I = Prev+1;
 566         LR = Prev;
 567       }
 568     }
 569
 570     // Okay, now we have a V1 or V2 live range that is maximally merged forward.
 571     // Ensure that it is a V2 live-range.
 572     LR->valno = V2;
 573
 574     // If we can merge it into later V2 live ranges, do so now.  We ignore any
 575     // following V1 live ranges, as they will be merged in subsequent iterations
 576     // of the loop.
 577     if (I != end()) {
 578       if (I->start == LR->end && I->valno == V2) {
 579         LR->end = I->end;
 580         ranges.erase(I);
 581         I = LR+1;
 582       }
 583     }
 584   }
 585
 586   // Merge the relevant flags.
 587   V2->mergeFlags(V1);
 588
 589   // Now that V1 is dead, remove it.
 590   markValNoForDeletion(V1);
 591
 592   return V2;
 593 }
 594
 595 void LiveInterval::Copy(const LiveInterval &RHS,
 596                         MachineRegisterInfo *MRI,
 597                         VNInfo::Allocator &VNInfoAllocator) {
 598   ranges.clear();
 599   valnos.clear();
 600   std::pair<unsigned, unsigned> Hint = MRI->getRegAllocationHint(RHS.reg);
 601   MRI->setRegAllocationHint(reg, Hint.first, Hint.second);
 602
 603   weight = RHS.weight;
 604   for (unsigned i = 0, e = RHS.getNumValNums(); i != e; ++i) {
 605     const VNInfo *VNI = RHS.getValNumInfo(i);
 606     createValueCopy(VNI, VNInfoAllocator);
 607   }
 608   for (unsigned i = 0, e = RHS.ranges.size(); i != e; ++i) {
 609     const LiveRange &LR = RHS.ranges[i];
 610     addRange(LiveRange(LR.start, LR.end, getValNumInfo(LR.valno->id)));
 611   }
 612 }
 613
 614 unsigned LiveInterval::getSize() const {
 615   unsigned Sum = 0;
 616   for (const_iterator I = begin(), E = end(); I != E; ++I)
 617     Sum += I->start.distance(I->end);
 618   return Sum;
 619 }
 620
 621 /// ComputeJoinedWeight - Set the weight of a live interval Joined
 622 /// after Other has been merged into it.
 623 void LiveInterval::ComputeJoinedWeight(const LiveInterval &Other) {
 624   // If either of these intervals was spilled, the weight is the
 625   // weight of the non-spilled interval.  This can only happen with
 626   // iterative coalescers.
 627
 628   if (Other.weight != HUGE_VALF) {
 629     weight += Other.weight;
 630   }
 631   else if (weight == HUGE_VALF &&
 632       !TargetRegisterInfo::isPhysicalRegister(reg)) {
 633     // Remove this assert if you have an iterative coalescer
 634     assert(0 && "Joining to spilled interval");
 635     weight = Other.weight;
 636   }
 637   else {
 638     // Otherwise the weight stays the same
 639     // Remove this assert if you have an iterative coalescer
 640     assert(0 && "Joining from spilled interval");
 641   }
 642 }
 643
 644 raw_ostream& llvm::operator<<(raw_ostream& os, const LiveRange &LR) {
 645   return os << '[' << LR.start << ',' << LR.end << ':' << LR.valno->id << ")";
 646 }
 647
 648 void LiveRange::dump() const {
 649   dbgs() << *this << "\n";
 650 }
 651
 652 void LiveInterval::print(raw_ostream &OS, const TargetRegisterInfo *TRI) const {
 653   if (isStackSlot())
 654     OS << "SS#" << getStackSlotIndex();
 655   else if (TRI && TargetRegisterInfo::isPhysicalRegister(reg))
 656     OS << TRI->getName(reg);
 657   else
 658     OS << "%reg" << reg;
 659
 660   OS << ',' << weight;
 661
 662   if (empty())
 663     OS << " EMPTY";
 664   else {
 665     OS << " = ";
 666     for (LiveInterval::Ranges::const_iterator I = ranges.begin(),
 667            E = ranges.end(); I != E; ++I) {
 668       OS << *I;
 669       assert(I->valno == getValNumInfo(I->valno->id) && "Bad VNInfo");
 670     }
 671   }
 672
 673   // Print value number info.
 674   if (getNumValNums()) {
 675     OS << "  ";
 676     unsigned vnum = 0;
 677     for (const_vni_iterator i = vni_begin(), e = vni_end(); i != e;
 678          ++i, ++vnum) {
 679       const VNInfo *vni = *i;
 680       if (vnum) OS << " ";
 681       OS << vnum << "@";
 682       if (vni->isUnused()) {
 683         OS << "x";
 684       } else {
 685         OS << vni->def;
 686         if (vni->isPHIDef())
 687           OS << "-phidef";
 688         if (vni->hasPHIKill())
 689           OS << "-phikill";
 690         if (vni->hasRedefByEC())
 691           OS << "-ec";
 692       }
 693     }
 694   }
 695 }
 696
 697 void LiveInterval::dump() const {
 698   dbgs() << *this << "\n";
 699 }
 700
 701
 702 void LiveRange::print(raw_ostream &os) const {
 703   os << *this;
 704 }
 705
 706 /// ConnectedVNInfoEqClasses - Helper class that can divide VNInfos in a
 707 /// LiveInterval into equivalence clases of connected components. A
 708 /// LiveInterval that has multiple connected components can be broken into
 709 /// multiple LiveIntervals.
 710
 711 void ConnectedVNInfoEqClasses::Connect(unsigned a, unsigned b) {
 712   while (eqClass_[a] != eqClass_[b]) {
 713     if (eqClass_[a] > eqClass_[b])
 714       std::swap(a, b);
 715     unsigned t = eqClass_[b];
 716     assert(t <= b && "Invariant broken");
 717     eqClass_[b] = eqClass_[a];
 718     b = t;
 719   }
 720 }
 721
 722 unsigned ConnectedVNInfoEqClasses::Renumber() {
 723   // Assign final class numbers.
 724   // We use the fact that eqClass_[i] == i for class leaders.
 725   // For others, eqClass_[i] points to an earlier value in the same class.
 726   unsigned count = 0;
 727   for (unsigned i = 0, e = eqClass_.size(); i != e; ++i) {
 728     unsigned q = eqClass_[i];
 729     assert(q <= i && "Invariant broken");
 730     eqClass_[i] = q == i ? count++ : eqClass_[q];
 731   }
 732
 733   return count;
 734 }
 735
 736 unsigned ConnectedVNInfoEqClasses::Classify(const LiveInterval *LI) {
 737   // Create initial equivalence classes.
 738   eqClass_.clear();
 739   eqClass_.reserve(LI->getNumValNums());
 740   for (unsigned i = 0, e = LI->getNumValNums(); i != e; ++i)
 741     eqClass_.push_back(i);
 742
 743   const VNInfo *used = 0, *unused = 0;
 744
 745   // Determine connections.
 746   for (LiveInterval::const_vni_iterator I = LI->vni_begin(), E = LI->vni_end();
 747        I != E; ++I) {
 748     const VNInfo *VNI = *I;
 749     // Group all unused values into one class.
 750     if (VNI->isUnused()) {
 751       if (unused)
 752         Connect(unused->id, VNI->id);
 753       unused = VNI;
 754       continue;
 755     }
 756     used = VNI;
 757     if (VNI->isPHIDef()) {
 758       const MachineBasicBlock *MBB = lis_.getMBBFromIndex(VNI->def);
 759       assert(MBB && "Phi-def has no defining MBB");
 760       // Connect to values live out of predecessors.
 761       for (MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(),
 762            PE = MBB->pred_end(); PI != PE; ++PI)
 763         if (const VNInfo *PVNI =
 764               LI->getVNInfoAt(lis_.getMBBEndIdx(*PI).getPrevSlot()))
 765           Connect(VNI->id, PVNI->id);
 766     } else {
 767       // Normal value defined by an instruction. Check for two-addr redef.
 768       // FIXME: This could be coincidental. Should we really check for a tied
 769       // operand constraint?
 770       if (const VNInfo *UVNI = LI->getVNInfoAt(VNI->def.getUseIndex()))
 771         Connect(VNI->id, UVNI->id);
 772     }
 773   }
 774
 775   // Lump all the unused values in with the last used value.
 776   if (used && unused)
 777     Connect(used->id, unused->id);
 778
 779   return Renumber();
 780 }
 781
 782 void ConnectedVNInfoEqClasses::Distribute(LiveInterval *LIV[]) {
 783   assert(LIV[0] && "LIV[0] must be set");
 784   LiveInterval &LI = *LIV[0];
 785   // Check that they likely ran Classify() on LIV[0] first.
 786   assert(eqClass_.size() == LI.getNumValNums() && "Bad classification data");
 787
 788   // First move runs to new intervals.
 789   LiveInterval::iterator J = LI.begin(), E = LI.end();
 790   while (J != E && eqClass_[J->valno->id] == 0)
 791     ++J;
 792   for (LiveInterval::iterator I = J; I != E; ++I) {
 793     if (unsigned eq = eqClass_[I->valno->id]) {
 794       assert((LIV[eq]->empty() || LIV[eq]->expiredAt(I->start)) &&
 795              "New intervals should be empty");
 796       LIV[eq]->ranges.push_back(*I);
 797     } else
 798       *J++ = *I;
 799   }
 800   LI.ranges.erase(J, E);
 801
 802   // Transfer VNInfos to their new owners and renumber them.
 803   unsigned j = 0, e = LI.getNumValNums();
 804   while (j != e && eqClass_[j] == 0)
 805     ++j;
 806   for (unsigned i = j; i != e; ++i) {
 807     VNInfo *VNI = LI.getValNumInfo(i);
 808     if (unsigned eq = eqClass_[i]) {
 809       VNI->id = LIV[eq]->getNumValNums();
 810       LIV[eq]->valnos.push_back(VNI);
 811     } else {
 812       VNI->id = j;
 813       LI.valnos[j++] = VNI;
 814     }
 815   }
 816   LI.valnos.resize(j);
 817 }