LiveDebugVariables.cpp revision 1dea232624c246341a5a98e0d481ba89f854012c 
1//===- LiveDebugVariables.cpp - Tracking debug info variables -------------===//
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 LiveDebugVariables analysis.
11//
12// Remove all DBG_VALUE instructions referencing virtual registers and replace
13// them with a data structure tracking where live user variables are kept - in a
14// virtual register or in a stack slot.
15//
16// Allow the data structure to be updated during register allocation when values
17// are moved between registers and stack slots. Finally emit new DBG_VALUE
18// instructions after register allocation is complete.
19//
20//===----------------------------------------------------------------------===//
21
22#define DEBUG_TYPE "livedebug"
23#include "LiveDebugVariables.h"
24#include "VirtRegMap.h"
25#include "llvm/Constants.h"
26#include "llvm/Metadata.h"
27#include "llvm/Value.h"
28#include "llvm/ADT/IntervalMap.h"
29#include "llvm/CodeGen/LiveIntervalAnalysis.h"
30#include "llvm/CodeGen/MachineDominators.h"
31#include "llvm/CodeGen/MachineFunction.h"
32#include "llvm/CodeGen/MachineInstrBuilder.h"
33#include "llvm/CodeGen/Passes.h"
34#include "llvm/Support/CommandLine.h"
35#include "llvm/Support/Debug.h"
36#include "llvm/Target/TargetInstrInfo.h"
37#include "llvm/Target/TargetMachine.h"
38#include "llvm/Target/TargetRegisterInfo.h"
39
40using namespace llvm;
41
42char LiveDebugVariables::ID = 0;
43
44INITIALIZE_PASS_BEGIN(LiveDebugVariables, "livedebugvars",
45                "Debug Variable Analysis", false, false)
46INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
47INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
48INITIALIZE_PASS_END(LiveDebugVariables, "livedebugvars",
49                "Debug Variable Analysis", false, false)
50
51void LiveDebugVariables::getAnalysisUsage(AnalysisUsage &AU) const {
52  AU.addRequired<MachineDominatorTree>();
53  AU.addRequiredTransitive<LiveIntervals>();
54  AU.setPreservesAll();
55  MachineFunctionPass::getAnalysisUsage(AU);
56}
57
58LiveDebugVariables::LiveDebugVariables() : MachineFunctionPass(ID), pImpl(0) {
59  initializeLiveDebugVariablesPass(*PassRegistry::getPassRegistry());
60}
61
62/// Location - All the different places a user value can reside.
63/// Note that this includes immediate values that technically aren't locations.
64namespace {
65struct Location {
66  /// kind - What kind of location is this?
67  enum Kind {
68    locUndef = 0,
69    locImm   = 0x80000000,
70    locFPImm
71  };
72  /// Kind - One of the following:
73  /// 1. locUndef
74  /// 2. Register number (physical or virtual), data.SubIdx is the subreg index.
75  /// 3. ~Frame index, data.Offset is the offset.
76  /// 4. locImm, data.ImmVal is the constant integer value.
77  /// 5. locFPImm, data.CFP points to the floating point constant.
78  unsigned Kind;
79
80  /// Data - Extra data about location.
81  union {
82    unsigned SubIdx;          ///< For virtual registers.
83    int64_t Offset;           ///< For frame indices.
84    int64_t ImmVal;           ///< For locImm.
85    const ConstantFP *CFP;    ///< For locFPImm.
86  } Data;
87
88  Location(const MachineOperand &MO) {
89    switch(MO.getType()) {
90    case MachineOperand::MO_Register:
91      Kind = MO.getReg();
92      Data.SubIdx = MO.getSubReg();
93      return;
94    case MachineOperand::MO_Immediate:
95      Kind = locImm;
96      Data.ImmVal = MO.getImm();
97      return;
98    case MachineOperand::MO_FPImmediate:
99      Kind = locFPImm;
100      Data.CFP = MO.getFPImm();
101      return;
102    case MachineOperand::MO_FrameIndex:
103      Kind = ~MO.getIndex();
104      // FIXME: MO_FrameIndex should support an offset.
105      Data.Offset = 0;
106      return;
107    default:
108      Kind = locUndef;
109      return;
110    }
111  }
112
113  /// addOperand - Add this location as a machine operand to MI.
114  MachineInstrBuilder addOperand(MachineInstrBuilder MI) const {
115    switch (Kind) {
116    case locImm:
117      return MI.addImm(Data.ImmVal);
118    case locFPImm:
119      return MI.addFPImm(Data.CFP);
120    default:
121      if (isFrameIndex())
122        return MI.addFrameIndex(getFrameIndex());
123      else
124        return MI.addReg(Kind);  // reg and undef.
125    }
126  }
127
128  bool operator==(const Location &RHS) const {
129    if (Kind != RHS.Kind)
130      return false;
131    switch (Kind) {
132    case locUndef:
133      return true;
134    case locImm:
135      return Data.ImmVal == RHS.Data.ImmVal;
136    case locFPImm:
137      return Data.CFP == RHS.Data.CFP;
138    default:
139      if (isReg())
140        return Data.SubIdx == RHS.Data.SubIdx;
141      else
142         return Data.Offset == RHS.Data.Offset;
143    }
144  }
145
146  /// isUndef - is this the singleton undef?
147  bool isUndef() const { return Kind == locUndef; }
148
149  /// isReg - is this a register location?
150  bool isReg() const { return Kind && Kind < locImm; }
151
152  /// isFrameIndex - is this a frame index location?
153  bool isFrameIndex() const { return Kind > locFPImm; }
154
155  int getFrameIndex() const { return ~Kind; }
156
157  void print(raw_ostream&, const TargetRegisterInfo*);
158};
159}
160
161/// LocMap - Map of where a user value is live, and its location.
162typedef IntervalMap<SlotIndex, unsigned, 4> LocMap;
163
164/// UserValue - A user value is a part of a debug info user variable.
165///
166/// A DBG_VALUE instruction notes that (a sub-register of) a virtual register
167/// holds part of a user variable. The part is identified by a byte offset.
168///
169/// UserValues are grouped into equivalence classes for easier searching. Two
170/// user values are related if they refer to the same variable, or if they are
171/// held by the same virtual register. The equivalence class is the transitive
172/// closure of that relation.
173namespace {
174class UserValue {
175  const MDNode *variable; ///< The debug info variable we are part of.
176  unsigned offset;        ///< Byte offset into variable.
177
178  UserValue *leader;      ///< Equivalence class leader.
179  UserValue *next;        ///< Next value in equivalence class, or null.
180
181  /// Numbered locations referenced by locmap.
182  SmallVector<Location, 4> locations;
183
184  /// Map of slot indices where this value is live.
185  LocMap locInts;
186
187  /// coalesceLocation - After LocNo was changed, check if it has become
188  /// identical to another location, and coalesce them. This may cause LocNo or
189  /// a later location to be erased, but no earlier location will be erased.
190  void coalesceLocation(unsigned LocNo);
191
192  /// insertDebugValue - Insert a DBG_VALUE into MBB at Idx for LocNo.
193  void insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx, unsigned LocNo,
194                        LiveIntervals &LIS, const TargetInstrInfo &TII);
195
196  /// insertDebugKill - Insert an undef DBG_VALUE into MBB at Idx.
197  void insertDebugKill(MachineBasicBlock *MBB, SlotIndex Idx,
198                       LiveIntervals &LIS, const TargetInstrInfo &TII);
199
200public:
201  /// UserValue - Create a new UserValue.
202  UserValue(const MDNode *var, unsigned o, LocMap::Allocator &alloc)
203    : variable(var), offset(o), leader(this), next(0), locInts(alloc)
204  {}
205
206  /// getLeader - Get the leader of this value's equivalence class.
207  UserValue *getLeader() {
208    UserValue *l = leader;
209    while (l != l->leader)
210      l = l->leader;
211    return leader = l;
212  }
213
214  /// getNext - Return the next UserValue in the equivalence class.
215  UserValue *getNext() const { return next; }
216
217  /// match - Does this UserValue match the aprameters?
218  bool match(const MDNode *Var, unsigned Offset) const {
219    return Var == variable && Offset == offset;
220  }
221
222  /// merge - Merge equivalence classes.
223  static UserValue *merge(UserValue *L1, UserValue *L2) {
224    L2 = L2->getLeader();
225    if (!L1)
226      return L2;
227    L1 = L1->getLeader();
228    if (L1 == L2)
229      return L1;
230    // Splice L2 before L1's members.
231    UserValue *End = L2;
232    while (End->next)
233      End->leader = L1, End = End->next;
234    End->leader = L1;
235    End->next = L1->next;
236    L1->next = L2;
237    return L1;
238  }
239
240  /// getLocationNo - Return the location number that matches Loc.
241  unsigned getLocationNo(Location Loc) {
242    if (Loc.isUndef())
243      return ~0u;
244    unsigned n = std::find(locations.begin(), locations.end(), Loc) -
245                 locations.begin();
246    if (n == locations.size())
247      locations.push_back(Loc);
248    return n;
249  }
250
251  /// addDef - Add a definition point to this value.
252  void addDef(SlotIndex Idx, const MachineOperand &LocMO) {
253    // Add a singular (Idx,Idx) -> Loc mapping.
254    LocMap::iterator I = locInts.find(Idx);
255    if (!I.valid() || I.start() != Idx)
256      I.insert(Idx, Idx.getNextSlot(), getLocationNo(LocMO));
257  }
258
259  /// extendDef - Extend the current definition as far as possible down the
260  /// dominator tree. Stop when meeting an existing def or when leaving the live
261  /// range of VNI.
262  /// @param Idx   Starting point for the definition.
263  /// @param LocNo Location number to propagate.
264  /// @param LI    Restrict liveness to where LI has the value VNI. May be null.
265  /// @param VNI   When LI is not null, this is the value to restrict to.
266  /// @param LIS   Live intervals analysis.
267  /// @param MDT   Dominator tree.
268  void extendDef(SlotIndex Idx, unsigned LocNo,
269                 LiveInterval *LI, const VNInfo *VNI,
270                 LiveIntervals &LIS, MachineDominatorTree &MDT);
271
272  /// computeIntervals - Compute the live intervals of all locations after
273  /// collecting all their def points.
274  void computeIntervals(LiveIntervals &LIS, MachineDominatorTree &MDT);
275
276  /// renameRegister - Update locations to rewrite OldReg as NewReg:SubIdx.
277  void renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx,
278                      const TargetRegisterInfo *TRI);
279
280  /// rewriteLocations - Rewrite virtual register locations according to the
281  /// provided virtual register map.
282  void rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI);
283
284  /// emitDebugVariables - Recreate DBG_VALUE instruction from data structures.
285  void emitDebugValues(VirtRegMap *VRM,
286                       LiveIntervals &LIS, const TargetInstrInfo &TRI);
287
288  void print(raw_ostream&, const TargetRegisterInfo*);
289};
290} // namespace
291
292/// LDVImpl - Implementation of the LiveDebugVariables pass.
293namespace {
294class LDVImpl {
295  LiveDebugVariables &pass;
296  LocMap::Allocator allocator;
297  MachineFunction *MF;
298  LiveIntervals *LIS;
299  MachineDominatorTree *MDT;
300  const TargetRegisterInfo *TRI;
301
302  /// userValues - All allocated UserValue instances.
303  SmallVector<UserValue*, 8> userValues;
304
305  /// Map virtual register to eq class leader.
306  typedef DenseMap<unsigned, UserValue*> VRMap;
307  VRMap virtRegToEqClass;
308
309  /// Map user variable to eq class leader.
310  typedef DenseMap<const MDNode *, UserValue*> UVMap;
311  UVMap userVarMap;
312
313  /// getUserValue - Find or create a UserValue.
314  UserValue *getUserValue(const MDNode *Var, unsigned Offset);
315
316  /// lookupVirtReg - Find the EC leader for VirtReg or null.
317  UserValue *lookupVirtReg(unsigned VirtReg);
318
319  /// mapVirtReg - Map virtual register to an equivalence class.
320  void mapVirtReg(unsigned VirtReg, UserValue *EC);
321
322  /// handleDebugValue - Add DBG_VALUE instruction to our maps.
323  /// @param MI  DBG_VALUE instruction
324  /// @param Idx Last valid SLotIndex before instruction.
325  /// @return    True if the DBG_VALUE instruction should be deleted.
326  bool handleDebugValue(MachineInstr *MI, SlotIndex Idx);
327
328  /// collectDebugValues - Collect and erase all DBG_VALUE instructions, adding
329  /// a UserValue def for each instruction.
330  /// @param mf MachineFunction to be scanned.
331  /// @return True if any debug values were found.
332  bool collectDebugValues(MachineFunction &mf);
333
334  /// computeIntervals - Compute the live intervals of all user values after
335  /// collecting all their def points.
336  void computeIntervals();
337
338public:
339  LDVImpl(LiveDebugVariables *ps) : pass(*ps) {}
340  bool runOnMachineFunction(MachineFunction &mf);
341
342  /// clear - Relase all memory.
343  void clear() {
344    DeleteContainerPointers(userValues);
345    userValues.clear();
346    virtRegToEqClass.clear();
347    userVarMap.clear();
348  }
349
350  /// renameRegister - Replace all references to OldReg wiht NewReg:SubIdx.
351  void renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx);
352
353  /// emitDebugVariables - Recreate DBG_VALUE instruction from data structures.
354  void emitDebugValues(VirtRegMap *VRM);
355
356  void print(raw_ostream&);
357};
358} // namespace
359
360void Location::print(raw_ostream &OS, const TargetRegisterInfo *TRI) {
361  switch (Kind) {
362  case locUndef:
363    OS << "undef";
364    return;
365  case locImm:
366    OS << "int:" << Data.ImmVal;
367    return;
368  case locFPImm:
369    OS << "fp:" << Data.CFP->getValueAPF().convertToDouble();
370    return;
371  default:
372    if (isReg()) {
373      if (TargetRegisterInfo::isVirtualRegister(Kind)) {
374        OS << "%reg" << Kind;
375        if (Data.SubIdx)
376          OS << ':' << TRI->getSubRegIndexName(Data.SubIdx);
377      } else
378        OS << '%' << TRI->getName(Kind);
379    } else {
380      OS << "fi#" << ~Kind;
381      if (Data.Offset)
382        OS << '+' << Data.Offset;
383    }
384    return;
385  }
386}
387
388void UserValue::print(raw_ostream &OS, const TargetRegisterInfo *TRI) {
389  if (const MDString *MDS = dyn_cast<MDString>(variable->getOperand(2)))
390    OS << "!\"" << MDS->getString() << "\"\t";
391  if (offset)
392    OS << '+' << offset;
393  for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) {
394    OS << " [" << I.start() << ';' << I.stop() << "):";
395    if (I.value() == ~0u)
396      OS << "undef";
397    else
398      OS << I.value();
399  }
400  for (unsigned i = 0, e = locations.size(); i != e; ++i) {
401    OS << " Loc" << i << '=';
402    locations[i].print(OS, TRI);
403  }
404  OS << '\n';
405}
406
407void LDVImpl::print(raw_ostream &OS) {
408  OS << "********** DEBUG VARIABLES **********\n";
409  for (unsigned i = 0, e = userValues.size(); i != e; ++i)
410    userValues[i]->print(OS, TRI);
411}
412
413void UserValue::coalesceLocation(unsigned LocNo) {
414  unsigned KeepLoc = std::find(locations.begin(), locations.begin() + LocNo,
415                               locations[LocNo]) - locations.begin();
416  unsigned EraseLoc = LocNo;
417  if (KeepLoc == LocNo) {
418    EraseLoc = std::find(locations.begin() + LocNo + 1, locations.end(),
419                         locations[LocNo]) - locations.begin();
420    // No matches.
421    if (EraseLoc == locations.size())
422      return;
423  }
424  assert(KeepLoc < EraseLoc);
425  locations.erase(locations.begin() + EraseLoc);
426
427  // Rewrite values.
428  for (LocMap::iterator I = locInts.begin(); I.valid(); ++I) {
429    unsigned v = I.value();
430    if (v == EraseLoc)
431      I.setValue(KeepLoc);      // Coalesce when possible.
432    else if (v > EraseLoc)
433      I.setValueUnchecked(v-1); // Avoid coalescing with untransformed values.
434  }
435}
436
437UserValue *LDVImpl::getUserValue(const MDNode *Var, unsigned Offset) {
438  UserValue *&Leader = userVarMap[Var];
439  if (Leader) {
440    UserValue *UV = Leader->getLeader();
441    Leader = UV;
442    for (; UV; UV = UV->getNext())
443      if (UV->match(Var, Offset))
444        return UV;
445  }
446
447  UserValue *UV = new UserValue(Var, Offset, allocator);
448  userValues.push_back(UV);
449  Leader = UserValue::merge(Leader, UV);
450  return UV;
451}
452
453void LDVImpl::mapVirtReg(unsigned VirtReg, UserValue *EC) {
454  assert(TargetRegisterInfo::isVirtualRegister(VirtReg) && "Only map VirtRegs");
455  UserValue *&Leader = virtRegToEqClass[VirtReg];
456  Leader = UserValue::merge(Leader, EC);
457}
458
459UserValue *LDVImpl::lookupVirtReg(unsigned VirtReg) {
460  if (UserValue *UV = virtRegToEqClass.lookup(VirtReg))
461    return UV->getLeader();
462  return 0;
463}
464
465bool LDVImpl::handleDebugValue(MachineInstr *MI, SlotIndex Idx) {
466  // DBG_VALUE loc, offset, variable
467  if (MI->getNumOperands() != 3 ||
468      !MI->getOperand(1).isImm() || !MI->getOperand(2).isMetadata()) {
469    DEBUG(dbgs() << "Can't handle " << *MI);
470    return false;
471  }
472
473  // Get or create the UserValue for (variable,offset).
474  unsigned Offset = MI->getOperand(1).getImm();
475  const MDNode *Var = MI->getOperand(2).getMetadata();
476  UserValue *UV = getUserValue(Var, Offset);
477
478  // If the location is a virtual register, make sure it is mapped.
479  if (MI->getOperand(0).isReg()) {
480    unsigned Reg = MI->getOperand(0).getReg();
481    if (Reg && TargetRegisterInfo::isVirtualRegister(Reg))
482      mapVirtReg(Reg, UV);
483  }
484
485  UV->addDef(Idx, MI->getOperand(0));
486  return true;
487}
488
489bool LDVImpl::collectDebugValues(MachineFunction &mf) {
490  bool Changed = false;
491  for (MachineFunction::iterator MFI = mf.begin(), MFE = mf.end(); MFI != MFE;
492       ++MFI) {
493    MachineBasicBlock *MBB = MFI;
494    for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
495         MBBI != MBBE;) {
496      if (!MBBI->isDebugValue()) {
497        ++MBBI;
498        continue;
499      }
500      // DBG_VALUE has no slot index, use the previous instruction instead.
501      SlotIndex Idx = MBBI == MBB->begin() ?
502        LIS->getMBBStartIdx(MBB) :
503        LIS->getInstructionIndex(llvm::prior(MBBI)).getDefIndex();
504      // Handle consecutive DBG_VALUE instructions with the same slot index.
505      do {
506        if (handleDebugValue(MBBI, Idx)) {
507          MBBI = MBB->erase(MBBI);
508          Changed = true;
509        } else
510          ++MBBI;
511      } while (MBBI != MBBE && MBBI->isDebugValue());
512    }
513  }
514  return Changed;
515}
516
517void UserValue::extendDef(SlotIndex Idx, unsigned LocNo,
518                          LiveInterval *LI, const VNInfo *VNI,
519                          LiveIntervals &LIS, MachineDominatorTree &MDT) {
520  SmallVector<SlotIndex, 16> Todo;
521  Todo.push_back(Idx);
522
523  do {
524    SlotIndex Start = Todo.pop_back_val();
525    MachineBasicBlock *MBB = LIS.getMBBFromIndex(Start);
526    SlotIndex Stop = LIS.getMBBEndIdx(MBB);
527    LocMap::iterator I = locInts.find(Idx);
528
529    // Limit to VNI's live range.
530    bool ToEnd = true;
531    if (LI && VNI) {
532      LiveRange *Range = LI->getLiveRangeContaining(Start);
533      if (!Range || Range->valno != VNI)
534        continue;
535      if (Range->end < Stop)
536        Stop = Range->end, ToEnd = false;
537    }
538
539    // There could already be a short def at Start.
540    if (I.valid() && I.start() <= Start) {
541      // Stop when meeting a different location or an already extended interval.
542      Start = Start.getNextSlot();
543      if (I.value() != LocNo || I.stop() != Start)
544        continue;
545      // This is a one-slot placeholder. Just skip it.
546      ++I;
547    }
548
549    // Limited by the next def.
550    if (I.valid() && I.start() < Stop)
551      Stop = I.start(), ToEnd = false;
552
553    if (Start >= Stop)
554      continue;
555
556    I.insert(Start, Stop, LocNo);
557
558    // If we extended to the MBB end, propagate down the dominator tree.
559    if (!ToEnd)
560      continue;
561    const std::vector<MachineDomTreeNode*> &Children =
562      MDT.getNode(MBB)->getChildren();
563    for (unsigned i = 0, e = Children.size(); i != e; ++i)
564      Todo.push_back(LIS.getMBBStartIdx(Children[i]->getBlock()));
565  } while (!Todo.empty());
566}
567
568void
569UserValue::computeIntervals(LiveIntervals &LIS, MachineDominatorTree &MDT) {
570  SmallVector<std::pair<SlotIndex, unsigned>, 16> Defs;
571
572  // Collect all defs to be extended (Skipping undefs).
573  for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I)
574    if (I.value() != ~0u)
575      Defs.push_back(std::make_pair(I.start(), I.value()));
576
577  for (unsigned i = 0, e = Defs.size(); i != e; ++i) {
578    SlotIndex Idx = Defs[i].first;
579    unsigned LocNo = Defs[i].second;
580    const Location &Loc = locations[LocNo];
581
582    // Register locations are constrained to where the register value is live.
583    if (Loc.isReg() && LIS.hasInterval(Loc.Kind)) {
584      LiveInterval *LI = &LIS.getInterval(Loc.Kind);
585      const VNInfo *VNI = LI->getVNInfoAt(Idx);
586      extendDef(Idx, LocNo, LI, VNI, LIS, MDT);
587    } else
588      extendDef(Idx, LocNo, 0, 0, LIS, MDT);
589  }
590
591  // Finally, erase all the undefs.
592  for (LocMap::iterator I = locInts.begin(); I.valid();)
593    if (I.value() == ~0u)
594      I.erase();
595    else
596      ++I;
597}
598
599void LDVImpl::computeIntervals() {
600  for (unsigned i = 0, e = userValues.size(); i != e; ++i)
601    userValues[i]->computeIntervals(*LIS, *MDT);
602}
603
604bool LDVImpl::runOnMachineFunction(MachineFunction &mf) {
605  MF = &mf;
606  LIS = &pass.getAnalysis<LiveIntervals>();
607  MDT = &pass.getAnalysis<MachineDominatorTree>();
608  TRI = mf.getTarget().getRegisterInfo();
609  clear();
610  DEBUG(dbgs() << "********** COMPUTING LIVE DEBUG VARIABLES: "
611               << ((Value*)mf.getFunction())->getName()
612               << " **********\n");
613
614  bool Changed = collectDebugValues(mf);
615  computeIntervals();
616  DEBUG(print(dbgs()));
617  return Changed;
618}
619
620bool LiveDebugVariables::runOnMachineFunction(MachineFunction &mf) {
621  if (!pImpl)
622    pImpl = new LDVImpl(this);
623  return static_cast<LDVImpl*>(pImpl)->runOnMachineFunction(mf);
624}
625
626void LiveDebugVariables::releaseMemory() {
627  if (pImpl)
628    static_cast<LDVImpl*>(pImpl)->clear();
629}
630
631LiveDebugVariables::~LiveDebugVariables() {
632  if (pImpl)
633    delete static_cast<LDVImpl*>(pImpl);
634}
635
636void UserValue::
637renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx,
638               const TargetRegisterInfo *TRI) {
639  for (unsigned i = locations.size(); i; --i) {
640    unsigned LocNo = i - 1;
641    Location &Loc = locations[LocNo];
642    if (Loc.Kind != OldReg)
643      continue;
644    Loc.Kind = NewReg;
645    if (SubIdx && Loc.Data.SubIdx)
646      Loc.Data.SubIdx = TRI->composeSubRegIndices(SubIdx, Loc.Data.SubIdx);
647    coalesceLocation(LocNo);
648  }
649}
650
651void LDVImpl::
652renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx) {
653  UserValue *UV = lookupVirtReg(OldReg);
654  if (!UV)
655    return;
656
657  if (TargetRegisterInfo::isVirtualRegister(NewReg))
658    mapVirtReg(NewReg, UV);
659  virtRegToEqClass.erase(OldReg);
660
661  do {
662    UV->renameRegister(OldReg, NewReg, SubIdx, TRI);
663    UV = UV->getNext();
664  } while (UV);
665}
666
667void LiveDebugVariables::
668renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx) {
669  if (pImpl)
670    static_cast<LDVImpl*>(pImpl)->renameRegister(OldReg, NewReg, SubIdx);
671}
672
673void
674UserValue::rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI) {
675  // Iterate over locations in reverse makes it easier to handle coalescing.
676  for (unsigned i = locations.size(); i ; --i) {
677    unsigned LocNo = i-1;
678    Location &Loc = locations[LocNo];
679    // Only virtual registers are rewritten.
680    if (!Loc.isReg() || !TargetRegisterInfo::isVirtualRegister(Loc.Kind))
681      continue;
682    unsigned VirtReg = Loc.Kind;
683    if (VRM.isAssignedReg(VirtReg)) {
684      unsigned PhysReg = VRM.getPhys(VirtReg);
685      if (Loc.Data.SubIdx)
686        PhysReg = TRI.getSubReg(PhysReg, Loc.Data.SubIdx);
687      Loc.Kind = PhysReg;
688      Loc.Data.SubIdx = 0;
689    } else if (VRM.getStackSlot(VirtReg) != VirtRegMap::NO_STACK_SLOT) {
690      Loc.Kind = ~VRM.getStackSlot(VirtReg);
691      // FIXME: Translate SubIdx to a stackslot offset.
692      Loc.Data.Offset = 0;
693    } else {
694      Loc.Kind = Location::locUndef;
695    }
696    coalesceLocation(LocNo);
697  }
698  DEBUG(print(dbgs(), &TRI));
699}
700
701/// findInsertLocation - Find an iterator and DebugLoc for inserting a DBG_VALUE
702/// instruction.
703static MachineBasicBlock::iterator
704findInsertLocation(MachineBasicBlock *MBB, SlotIndex Idx, DebugLoc &DL,
705                   LiveIntervals &LIS) {
706  SlotIndex Start = LIS.getMBBStartIdx(MBB);
707  Idx = Idx.getBaseIndex();
708
709  // Try to find an insert location by going backwards from Idx.
710  MachineInstr *MI;
711  while (!(MI = LIS.getInstructionFromIndex(Idx))) {
712    // We've reached the beginning of MBB.
713    if (Idx == Start) {
714      MachineBasicBlock::iterator I = MBB->SkipPHIsAndLabels(MBB->begin());
715      if (I != MBB->end())
716        DL = I->getDebugLoc();
717      return I;
718    }
719    Idx = Idx.getPrevIndex();
720  }
721  // We found an instruction. The insert point is after the instr.
722  DL = MI->getDebugLoc();
723  return llvm::next(MachineBasicBlock::iterator(MI));
724}
725
726void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx,
727                                 unsigned LocNo,
728                                 LiveIntervals &LIS,
729                                 const TargetInstrInfo &TII) {
730  DebugLoc DL;
731  MachineBasicBlock::iterator I = findInsertLocation(MBB, Idx, DL, LIS);
732  Location &Loc = locations[LocNo];
733
734  // Frame index locations may require a target callback.
735  if (Loc.isFrameIndex()) {
736    MachineInstr *MI = TII.emitFrameIndexDebugValue(*MBB->getParent(),
737                                          Loc.getFrameIndex(),
738                                          offset, variable, DL);
739    if (MI) {
740      MBB->insert(I, MI);
741      return;
742    }
743  }
744  // This is not a frame index, or the target is happy with a standard FI.
745  Loc.addOperand(BuildMI(*MBB, I, DL, TII.get(TargetOpcode::DBG_VALUE)))
746    .addImm(offset).addMetadata(variable);
747}
748
749void UserValue::insertDebugKill(MachineBasicBlock *MBB, SlotIndex Idx,
750                               LiveIntervals &LIS, const TargetInstrInfo &TII) {
751  DebugLoc DL;
752  MachineBasicBlock::iterator I = findInsertLocation(MBB, Idx, DL, LIS);
753  BuildMI(*MBB, I, DL, TII.get(TargetOpcode::DBG_VALUE)).addReg(0)
754    .addImm(offset).addMetadata(variable);
755}
756
757void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
758                                const TargetInstrInfo &TII) {
759  MachineFunction::iterator MFEnd = VRM->getMachineFunction().end();
760
761  for (LocMap::const_iterator I = locInts.begin(); I.valid();) {
762    SlotIndex Start = I.start();
763    SlotIndex Stop = I.stop();
764    unsigned LocNo = I.value();
765    DEBUG(dbgs() << "\t[" << Start << ';' << Stop << "):" << LocNo);
766    MachineFunction::iterator MBB = LIS.getMBBFromIndex(Start);
767    SlotIndex MBBEnd = LIS.getMBBEndIdx(MBB);
768
769    DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
770    insertDebugValue(MBB, Start, LocNo, LIS, TII);
771
772    // This interval may span multiple basic blocks.
773    // Insert a DBG_VALUE into each one.
774    while(Stop > MBBEnd) {
775      // Move to the next block.
776      Start = MBBEnd;
777      if (++MBB == MFEnd)
778        break;
779      MBBEnd = LIS.getMBBEndIdx(MBB);
780      DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
781      insertDebugValue(MBB, Start, LocNo, LIS, TII);
782    }
783    DEBUG(dbgs() << '\n');
784    if (MBB == MFEnd)
785      break;
786
787    ++I;
788    if (Stop == MBBEnd)
789      continue;
790    // The current interval ends before MBB.
791    // Insert a kill if there is a gap.
792    if (!I.valid() || I.start() > Stop)
793      insertDebugKill(MBB, Stop, LIS, TII);
794  }
795}
796
797void LDVImpl::emitDebugValues(VirtRegMap *VRM) {
798  DEBUG(dbgs() << "********** EMITTING LIVE DEBUG VARIABLES **********\n");
799  const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
800  for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
801    userValues[i]->rewriteLocations(*VRM, *TRI);
802    userValues[i]->emitDebugValues(VRM, *LIS, *TII);
803  }
804}
805
806void LiveDebugVariables::emitDebugValues(VirtRegMap *VRM) {
807  if (pImpl)
808    static_cast<LDVImpl*>(pImpl)->emitDebugValues(VRM);
809}
810
811
812#ifndef NDEBUG
813void LiveDebugVariables::dump() {
814  if (pImpl)
815    static_cast<LDVImpl*>(pImpl)->print(dbgs());
816}
817#endif
818
819