LiveDebugVariables.cpp revision 7a2bdde0a0eebcd2125055e0eacaca040f0b766c 
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/MachineRegisterInfo.h"
34#include "llvm/CodeGen/Passes.h"
35#include "llvm/Support/CommandLine.h"
36#include "llvm/Support/Debug.h"
37#include "llvm/Target/TargetInstrInfo.h"
38#include "llvm/Target/TargetMachine.h"
39#include "llvm/Target/TargetRegisterInfo.h"
40
41using namespace llvm;
42
43static cl::opt<bool>
44EnableLDV("live-debug-variables", cl::init(true),
45          cl::desc("Enable the live debug variables pass"), cl::Hidden);
46
47char LiveDebugVariables::ID = 0;
48
49INITIALIZE_PASS_BEGIN(LiveDebugVariables, "livedebugvars",
50                "Debug Variable Analysis", false, false)
51INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
52INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
53INITIALIZE_PASS_END(LiveDebugVariables, "livedebugvars",
54                "Debug Variable Analysis", false, false)
55
56void LiveDebugVariables::getAnalysisUsage(AnalysisUsage &AU) const {
57  AU.addRequired<MachineDominatorTree>();
58  AU.addRequiredTransitive<LiveIntervals>();
59  AU.setPreservesAll();
60  MachineFunctionPass::getAnalysisUsage(AU);
61}
62
63LiveDebugVariables::LiveDebugVariables() : MachineFunctionPass(ID), pImpl(0) {
64  initializeLiveDebugVariablesPass(*PassRegistry::getPassRegistry());
65}
66
67/// LocMap - Map of where a user value is live, and its location.
68typedef IntervalMap<SlotIndex, unsigned, 4> LocMap;
69
70/// UserValue - A user value is a part of a debug info user variable.
71///
72/// A DBG_VALUE instruction notes that (a sub-register of) a virtual register
73/// holds part of a user variable. The part is identified by a byte offset.
74///
75/// UserValues are grouped into equivalence classes for easier searching. Two
76/// user values are related if they refer to the same variable, or if they are
77/// held by the same virtual register. The equivalence class is the transitive
78/// closure of that relation.
79namespace {
80class LDVImpl;
81class UserValue {
82  const MDNode *variable; ///< The debug info variable we are part of.
83  unsigned offset;        ///< Byte offset into variable.
84  DebugLoc dl;            ///< The debug location for the variable. This is
85                          ///< used by dwarf writer to find lexical scope.
86  UserValue *leader;      ///< Equivalence class leader.
87  UserValue *next;        ///< Next value in equivalence class, or null.
88
89  /// Numbered locations referenced by locmap.
90  SmallVector<MachineOperand, 4> locations;
91
92  /// Map of slot indices where this value is live.
93  LocMap locInts;
94
95  /// coalesceLocation - After LocNo was changed, check if it has become
96  /// identical to another location, and coalesce them. This may cause LocNo or
97  /// a later location to be erased, but no earlier location will be erased.
98  void coalesceLocation(unsigned LocNo);
99
100  /// insertDebugValue - Insert a DBG_VALUE into MBB at Idx for LocNo.
101  void insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx, unsigned LocNo,
102                        LiveIntervals &LIS, const TargetInstrInfo &TII);
103
104public:
105  /// UserValue - Create a new UserValue.
106  UserValue(const MDNode *var, unsigned o, DebugLoc L,
107            LocMap::Allocator &alloc)
108    : variable(var), offset(o), dl(L), leader(this), next(0), locInts(alloc)
109  {}
110
111  /// getLeader - Get the leader of this value's equivalence class.
112  UserValue *getLeader() {
113    UserValue *l = leader;
114    while (l != l->leader)
115      l = l->leader;
116    return leader = l;
117  }
118
119  /// getNext - Return the next UserValue in the equivalence class.
120  UserValue *getNext() const { return next; }
121
122  /// match - Does this UserValue match the aprameters?
123  bool match(const MDNode *Var, unsigned Offset) const {
124    return Var == variable && Offset == offset;
125  }
126
127  /// merge - Merge equivalence classes.
128  static UserValue *merge(UserValue *L1, UserValue *L2) {
129    L2 = L2->getLeader();
130    if (!L1)
131      return L2;
132    L1 = L1->getLeader();
133    if (L1 == L2)
134      return L1;
135    // Splice L2 before L1's members.
136    UserValue *End = L2;
137    while (End->next)
138      End->leader = L1, End = End->next;
139    End->leader = L1;
140    End->next = L1->next;
141    L1->next = L2;
142    return L1;
143  }
144
145  /// getLocationNo - Return the location number that matches Loc.
146  unsigned getLocationNo(const MachineOperand &LocMO) {
147    if (LocMO.isReg()) {
148      if (LocMO.getReg() == 0)
149        return ~0u;
150      // For register locations we dont care about use/def and other flags.
151      for (unsigned i = 0, e = locations.size(); i != e; ++i)
152        if (locations[i].isReg() &&
153            locations[i].getReg() == LocMO.getReg() &&
154            locations[i].getSubReg() == LocMO.getSubReg())
155          return i;
156    } else
157      for (unsigned i = 0, e = locations.size(); i != e; ++i)
158        if (LocMO.isIdenticalTo(locations[i]))
159          return i;
160    locations.push_back(LocMO);
161    // We are storing a MachineOperand outside a MachineInstr.
162    locations.back().clearParent();
163    // Don't store def operands.
164    if (locations.back().isReg())
165      locations.back().setIsUse();
166    return locations.size() - 1;
167  }
168
169  /// mapVirtRegs - Ensure that all virtual register locations are mapped.
170  void mapVirtRegs(LDVImpl *LDV);
171
172  /// addDef - Add a definition point to this value.
173  void addDef(SlotIndex Idx, const MachineOperand &LocMO) {
174    // Add a singular (Idx,Idx) -> Loc mapping.
175    LocMap::iterator I = locInts.find(Idx);
176    if (!I.valid() || I.start() != Idx)
177      I.insert(Idx, Idx.getNextSlot(), getLocationNo(LocMO));
178  }
179
180  /// extendDef - Extend the current definition as far as possible down the
181  /// dominator tree. Stop when meeting an existing def or when leaving the live
182  /// range of VNI.
183  /// End points where VNI is no longer live are added to Kills.
184  /// @param Idx   Starting point for the definition.
185  /// @param LocNo Location number to propagate.
186  /// @param LI    Restrict liveness to where LI has the value VNI. May be null.
187  /// @param VNI   When LI is not null, this is the value to restrict to.
188  /// @param Kills Append end points of VNI's live range to Kills.
189  /// @param LIS   Live intervals analysis.
190  /// @param MDT   Dominator tree.
191  void extendDef(SlotIndex Idx, unsigned LocNo,
192                 LiveInterval *LI, const VNInfo *VNI,
193                 SmallVectorImpl<SlotIndex> *Kills,
194                 LiveIntervals &LIS, MachineDominatorTree &MDT);
195
196  /// addDefsFromCopies - The value in LI/LocNo may be copies to other
197  /// registers. Determine if any of the copies are available at the kill
198  /// points, and add defs if possible.
199  /// @param LI      Scan for copies of the value in LI->reg.
200  /// @param LocNo   Location number of LI->reg.
201  /// @param Kills   Points where the range of LocNo could be extended.
202  /// @param NewDefs Append (Idx, LocNo) of inserted defs here.
203  void addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
204                      const SmallVectorImpl<SlotIndex> &Kills,
205                      SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
206                      MachineRegisterInfo &MRI,
207                      LiveIntervals &LIS);
208
209  /// computeIntervals - Compute the live intervals of all locations after
210  /// collecting all their def points.
211  void computeIntervals(MachineRegisterInfo &MRI,
212                        LiveIntervals &LIS, MachineDominatorTree &MDT);
213
214  /// renameRegister - Update locations to rewrite OldReg as NewReg:SubIdx.
215  void renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx,
216                      const TargetRegisterInfo *TRI);
217
218  /// rewriteLocations - Rewrite virtual register locations according to the
219  /// provided virtual register map.
220  void rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI);
221
222  /// emitDebugVariables - Recreate DBG_VALUE instruction from data structures.
223  void emitDebugValues(VirtRegMap *VRM,
224                       LiveIntervals &LIS, const TargetInstrInfo &TRI);
225
226  /// findDebugLoc - Return DebugLoc used for this DBG_VALUE instruction. A
227  /// variable may have more than one corresponding DBG_VALUE instructions.
228  /// Only first one needs DebugLoc to identify variable's lexical scope
229  /// in source file.
230  DebugLoc findDebugLoc();
231  void print(raw_ostream&, const TargetRegisterInfo*);
232};
233} // namespace
234
235/// LDVImpl - Implementation of the LiveDebugVariables pass.
236namespace {
237class LDVImpl {
238  LiveDebugVariables &pass;
239  LocMap::Allocator allocator;
240  MachineFunction *MF;
241  LiveIntervals *LIS;
242  MachineDominatorTree *MDT;
243  const TargetRegisterInfo *TRI;
244
245  /// userValues - All allocated UserValue instances.
246  SmallVector<UserValue*, 8> userValues;
247
248  /// Map virtual register to eq class leader.
249  typedef DenseMap<unsigned, UserValue*> VRMap;
250  VRMap virtRegToEqClass;
251
252  /// Map user variable to eq class leader.
253  typedef DenseMap<const MDNode *, UserValue*> UVMap;
254  UVMap userVarMap;
255
256  /// getUserValue - Find or create a UserValue.
257  UserValue *getUserValue(const MDNode *Var, unsigned Offset, DebugLoc DL);
258
259  /// lookupVirtReg - Find the EC leader for VirtReg or null.
260  UserValue *lookupVirtReg(unsigned VirtReg);
261
262  /// handleDebugValue - Add DBG_VALUE instruction to our maps.
263  /// @param MI  DBG_VALUE instruction
264  /// @param Idx Last valid SLotIndex before instruction.
265  /// @return    True if the DBG_VALUE instruction should be deleted.
266  bool handleDebugValue(MachineInstr *MI, SlotIndex Idx);
267
268  /// collectDebugValues - Collect and erase all DBG_VALUE instructions, adding
269  /// a UserValue def for each instruction.
270  /// @param mf MachineFunction to be scanned.
271  /// @return True if any debug values were found.
272  bool collectDebugValues(MachineFunction &mf);
273
274  /// computeIntervals - Compute the live intervals of all user values after
275  /// collecting all their def points.
276  void computeIntervals();
277
278public:
279  LDVImpl(LiveDebugVariables *ps) : pass(*ps) {}
280  bool runOnMachineFunction(MachineFunction &mf);
281
282  /// clear - Relase all memory.
283  void clear() {
284    DeleteContainerPointers(userValues);
285    userValues.clear();
286    virtRegToEqClass.clear();
287    userVarMap.clear();
288  }
289
290  /// mapVirtReg - Map virtual register to an equivalence class.
291  void mapVirtReg(unsigned VirtReg, UserValue *EC);
292
293  /// renameRegister - Replace all references to OldReg with NewReg:SubIdx.
294  void renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx);
295
296  /// emitDebugVariables - Recreate DBG_VALUE instruction from data structures.
297  void emitDebugValues(VirtRegMap *VRM);
298
299  void print(raw_ostream&);
300};
301} // namespace
302
303void UserValue::print(raw_ostream &OS, const TargetRegisterInfo *TRI) {
304  if (const MDString *MDS = dyn_cast<MDString>(variable->getOperand(2)))
305    OS << "!\"" << MDS->getString() << "\"\t";
306  if (offset)
307    OS << '+' << offset;
308  for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) {
309    OS << " [" << I.start() << ';' << I.stop() << "):";
310    if (I.value() == ~0u)
311      OS << "undef";
312    else
313      OS << I.value();
314  }
315  for (unsigned i = 0, e = locations.size(); i != e; ++i)
316    OS << " Loc" << i << '=' << locations[i];
317  OS << '\n';
318}
319
320void LDVImpl::print(raw_ostream &OS) {
321  OS << "********** DEBUG VARIABLES **********\n";
322  for (unsigned i = 0, e = userValues.size(); i != e; ++i)
323    userValues[i]->print(OS, TRI);
324}
325
326void UserValue::coalesceLocation(unsigned LocNo) {
327  unsigned KeepLoc = 0;
328  for (unsigned e = locations.size(); KeepLoc != e; ++KeepLoc) {
329    if (KeepLoc == LocNo)
330      continue;
331    if (locations[KeepLoc].isIdenticalTo(locations[LocNo]))
332      break;
333  }
334  // No matches.
335  if (KeepLoc == locations.size())
336    return;
337
338  // Keep the smaller location, erase the larger one.
339  unsigned EraseLoc = LocNo;
340  if (KeepLoc > EraseLoc)
341    std::swap(KeepLoc, EraseLoc);
342  locations.erase(locations.begin() + EraseLoc);
343
344  // Rewrite values.
345  for (LocMap::iterator I = locInts.begin(); I.valid(); ++I) {
346    unsigned v = I.value();
347    if (v == EraseLoc)
348      I.setValue(KeepLoc);      // Coalesce when possible.
349    else if (v > EraseLoc)
350      I.setValueUnchecked(v-1); // Avoid coalescing with untransformed values.
351  }
352}
353
354void UserValue::mapVirtRegs(LDVImpl *LDV) {
355  for (unsigned i = 0, e = locations.size(); i != e; ++i)
356    if (locations[i].isReg() &&
357        TargetRegisterInfo::isVirtualRegister(locations[i].getReg()))
358      LDV->mapVirtReg(locations[i].getReg(), this);
359}
360
361UserValue *LDVImpl::getUserValue(const MDNode *Var, unsigned Offset,
362                                 DebugLoc DL) {
363  UserValue *&Leader = userVarMap[Var];
364  if (Leader) {
365    UserValue *UV = Leader->getLeader();
366    Leader = UV;
367    for (; UV; UV = UV->getNext())
368      if (UV->match(Var, Offset))
369        return UV;
370  }
371
372  UserValue *UV = new UserValue(Var, Offset, DL, allocator);
373  userValues.push_back(UV);
374  Leader = UserValue::merge(Leader, UV);
375  return UV;
376}
377
378void LDVImpl::mapVirtReg(unsigned VirtReg, UserValue *EC) {
379  assert(TargetRegisterInfo::isVirtualRegister(VirtReg) && "Only map VirtRegs");
380  UserValue *&Leader = virtRegToEqClass[VirtReg];
381  Leader = UserValue::merge(Leader, EC);
382}
383
384UserValue *LDVImpl::lookupVirtReg(unsigned VirtReg) {
385  if (UserValue *UV = virtRegToEqClass.lookup(VirtReg))
386    return UV->getLeader();
387  return 0;
388}
389
390bool LDVImpl::handleDebugValue(MachineInstr *MI, SlotIndex Idx) {
391  // DBG_VALUE loc, offset, variable
392  if (MI->getNumOperands() != 3 ||
393      !MI->getOperand(1).isImm() || !MI->getOperand(2).isMetadata()) {
394    DEBUG(dbgs() << "Can't handle " << *MI);
395    return false;
396  }
397
398  // Get or create the UserValue for (variable,offset).
399  unsigned Offset = MI->getOperand(1).getImm();
400  const MDNode *Var = MI->getOperand(2).getMetadata();
401  UserValue *UV = getUserValue(Var, Offset, MI->getDebugLoc());
402  UV->addDef(Idx, MI->getOperand(0));
403  return true;
404}
405
406bool LDVImpl::collectDebugValues(MachineFunction &mf) {
407  bool Changed = false;
408  for (MachineFunction::iterator MFI = mf.begin(), MFE = mf.end(); MFI != MFE;
409       ++MFI) {
410    MachineBasicBlock *MBB = MFI;
411    for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
412         MBBI != MBBE;) {
413      if (!MBBI->isDebugValue()) {
414        ++MBBI;
415        continue;
416      }
417      // DBG_VALUE has no slot index, use the previous instruction instead.
418      SlotIndex Idx = MBBI == MBB->begin() ?
419        LIS->getMBBStartIdx(MBB) :
420        LIS->getInstructionIndex(llvm::prior(MBBI)).getDefIndex();
421      // Handle consecutive DBG_VALUE instructions with the same slot index.
422      do {
423        if (handleDebugValue(MBBI, Idx)) {
424          MBBI = MBB->erase(MBBI);
425          Changed = true;
426        } else
427          ++MBBI;
428      } while (MBBI != MBBE && MBBI->isDebugValue());
429    }
430  }
431  return Changed;
432}
433
434void UserValue::extendDef(SlotIndex Idx, unsigned LocNo,
435                          LiveInterval *LI, const VNInfo *VNI,
436                          SmallVectorImpl<SlotIndex> *Kills,
437                          LiveIntervals &LIS, MachineDominatorTree &MDT) {
438  SmallVector<SlotIndex, 16> Todo;
439  Todo.push_back(Idx);
440
441  do {
442    SlotIndex Start = Todo.pop_back_val();
443    MachineBasicBlock *MBB = LIS.getMBBFromIndex(Start);
444    SlotIndex Stop = LIS.getMBBEndIdx(MBB);
445    LocMap::iterator I = locInts.find(Start);
446
447    // Limit to VNI's live range.
448    bool ToEnd = true;
449    if (LI && VNI) {
450      LiveRange *Range = LI->getLiveRangeContaining(Start);
451      if (!Range || Range->valno != VNI) {
452        if (Kills)
453          Kills->push_back(Start);
454        continue;
455      }
456      if (Range->end < Stop)
457        Stop = Range->end, ToEnd = false;
458    }
459
460    // There could already be a short def at Start.
461    if (I.valid() && I.start() <= Start) {
462      // Stop when meeting a different location or an already extended interval.
463      Start = Start.getNextSlot();
464      if (I.value() != LocNo || I.stop() != Start)
465        continue;
466      // This is a one-slot placeholder. Just skip it.
467      ++I;
468    }
469
470    // Limited by the next def.
471    if (I.valid() && I.start() < Stop)
472      Stop = I.start(), ToEnd = false;
473    // Limited by VNI's live range.
474    else if (!ToEnd && Kills)
475      Kills->push_back(Stop);
476
477    if (Start >= Stop)
478      continue;
479
480    I.insert(Start, Stop, LocNo);
481
482    // If we extended to the MBB end, propagate down the dominator tree.
483    if (!ToEnd)
484      continue;
485    const std::vector<MachineDomTreeNode*> &Children =
486      MDT.getNode(MBB)->getChildren();
487    for (unsigned i = 0, e = Children.size(); i != e; ++i)
488      Todo.push_back(LIS.getMBBStartIdx(Children[i]->getBlock()));
489  } while (!Todo.empty());
490}
491
492void
493UserValue::addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
494                      const SmallVectorImpl<SlotIndex> &Kills,
495                      SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
496                      MachineRegisterInfo &MRI, LiveIntervals &LIS) {
497  if (Kills.empty())
498    return;
499  // Don't track copies from physregs, there are too many uses.
500  if (!TargetRegisterInfo::isVirtualRegister(LI->reg))
501    return;
502
503  // Collect all the (vreg, valno) pairs that are copies of LI.
504  SmallVector<std::pair<LiveInterval*, const VNInfo*>, 8> CopyValues;
505  for (MachineRegisterInfo::use_nodbg_iterator
506         UI = MRI.use_nodbg_begin(LI->reg),
507         UE = MRI.use_nodbg_end(); UI != UE; ++UI) {
508    // Copies of the full value.
509    if (UI.getOperand().getSubReg() || !UI->isCopy())
510      continue;
511    MachineInstr *MI = &*UI;
512    unsigned DstReg = MI->getOperand(0).getReg();
513
514    // Don't follow copies to physregs. These are usually setting up call
515    // arguments, and the argument registers are always call clobbered. We are
516    // better off in the source register which could be a callee-saved register,
517    // or it could be spilled.
518    if (!TargetRegisterInfo::isVirtualRegister(DstReg))
519      continue;
520
521    // Is LocNo extended to reach this copy? If not, another def may be blocking
522    // it, or we are looking at a wrong value of LI.
523    SlotIndex Idx = LIS.getInstructionIndex(MI);
524    LocMap::iterator I = locInts.find(Idx.getUseIndex());
525    if (!I.valid() || I.value() != LocNo)
526      continue;
527
528    if (!LIS.hasInterval(DstReg))
529      continue;
530    LiveInterval *DstLI = &LIS.getInterval(DstReg);
531    const VNInfo *DstVNI = DstLI->getVNInfoAt(Idx.getDefIndex());
532    assert(DstVNI && DstVNI->def == Idx.getDefIndex() && "Bad copy value");
533    CopyValues.push_back(std::make_pair(DstLI, DstVNI));
534  }
535
536  if (CopyValues.empty())
537    return;
538
539  DEBUG(dbgs() << "Got " << CopyValues.size() << " copies of " << *LI << '\n');
540
541  // Try to add defs of the copied values for each kill point.
542  for (unsigned i = 0, e = Kills.size(); i != e; ++i) {
543    SlotIndex Idx = Kills[i];
544    for (unsigned j = 0, e = CopyValues.size(); j != e; ++j) {
545      LiveInterval *DstLI = CopyValues[j].first;
546      const VNInfo *DstVNI = CopyValues[j].second;
547      if (DstLI->getVNInfoAt(Idx) != DstVNI)
548        continue;
549      // Check that there isn't already a def at Idx
550      LocMap::iterator I = locInts.find(Idx);
551      if (I.valid() && I.start() <= Idx)
552        continue;
553      DEBUG(dbgs() << "Kill at " << Idx << " covered by valno #"
554                   << DstVNI->id << " in " << *DstLI << '\n');
555      MachineInstr *CopyMI = LIS.getInstructionFromIndex(DstVNI->def);
556      assert(CopyMI && CopyMI->isCopy() && "Bad copy value");
557      unsigned LocNo = getLocationNo(CopyMI->getOperand(0));
558      I.insert(Idx, Idx.getNextSlot(), LocNo);
559      NewDefs.push_back(std::make_pair(Idx, LocNo));
560      break;
561    }
562  }
563}
564
565void
566UserValue::computeIntervals(MachineRegisterInfo &MRI,
567                            LiveIntervals &LIS,
568                            MachineDominatorTree &MDT) {
569  SmallVector<std::pair<SlotIndex, unsigned>, 16> Defs;
570
571  // Collect all defs to be extended (Skipping undefs).
572  for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I)
573    if (I.value() != ~0u)
574      Defs.push_back(std::make_pair(I.start(), I.value()));
575
576  // Extend all defs, and possibly add new ones along the way.
577  for (unsigned i = 0; i != Defs.size(); ++i) {
578    SlotIndex Idx = Defs[i].first;
579    unsigned LocNo = Defs[i].second;
580    const MachineOperand &Loc = locations[LocNo];
581
582    // Register locations are constrained to where the register value is live.
583    if (Loc.isReg() && LIS.hasInterval(Loc.getReg())) {
584      LiveInterval *LI = &LIS.getInterval(Loc.getReg());
585      const VNInfo *VNI = LI->getVNInfoAt(Idx);
586      SmallVector<SlotIndex, 16> Kills;
587      extendDef(Idx, LocNo, LI, VNI, &Kills, LIS, MDT);
588      addDefsFromCopies(LI, LocNo, Kills, Defs, MRI, LIS);
589    } else
590      extendDef(Idx, LocNo, 0, 0, 0, LIS, MDT);
591  }
592
593  // Finally, erase all the undefs.
594  for (LocMap::iterator I = locInts.begin(); I.valid();)
595    if (I.value() == ~0u)
596      I.erase();
597    else
598      ++I;
599}
600
601void LDVImpl::computeIntervals() {
602  for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
603    userValues[i]->computeIntervals(MF->getRegInfo(), *LIS, *MDT);
604    userValues[i]->mapVirtRegs(this);
605  }
606}
607
608bool LDVImpl::runOnMachineFunction(MachineFunction &mf) {
609  MF = &mf;
610  LIS = &pass.getAnalysis<LiveIntervals>();
611  MDT = &pass.getAnalysis<MachineDominatorTree>();
612  TRI = mf.getTarget().getRegisterInfo();
613  clear();
614  DEBUG(dbgs() << "********** COMPUTING LIVE DEBUG VARIABLES: "
615               << ((Value*)mf.getFunction())->getName()
616               << " **********\n");
617
618  bool Changed = collectDebugValues(mf);
619  computeIntervals();
620  DEBUG(print(dbgs()));
621  return Changed;
622}
623
624bool LiveDebugVariables::runOnMachineFunction(MachineFunction &mf) {
625  if (!EnableLDV)
626    return false;
627  if (!pImpl)
628    pImpl = new LDVImpl(this);
629  return static_cast<LDVImpl*>(pImpl)->runOnMachineFunction(mf);
630}
631
632void LiveDebugVariables::releaseMemory() {
633  if (pImpl)
634    static_cast<LDVImpl*>(pImpl)->clear();
635}
636
637LiveDebugVariables::~LiveDebugVariables() {
638  if (pImpl)
639    delete static_cast<LDVImpl*>(pImpl);
640}
641
642void UserValue::
643renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx,
644               const TargetRegisterInfo *TRI) {
645  for (unsigned i = locations.size(); i; --i) {
646    unsigned LocNo = i - 1;
647    MachineOperand &Loc = locations[LocNo];
648    if (!Loc.isReg() || Loc.getReg() != OldReg)
649      continue;
650    if (TargetRegisterInfo::isPhysicalRegister(NewReg))
651      Loc.substPhysReg(NewReg, *TRI);
652    else
653      Loc.substVirtReg(NewReg, SubIdx, *TRI);
654    coalesceLocation(LocNo);
655  }
656}
657
658void LDVImpl::
659renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx) {
660  UserValue *UV = lookupVirtReg(OldReg);
661  if (!UV)
662    return;
663
664  if (TargetRegisterInfo::isVirtualRegister(NewReg))
665    mapVirtReg(NewReg, UV);
666  virtRegToEqClass.erase(OldReg);
667
668  do {
669    UV->renameRegister(OldReg, NewReg, SubIdx, TRI);
670    UV = UV->getNext();
671  } while (UV);
672}
673
674void LiveDebugVariables::
675renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx) {
676  if (pImpl)
677    static_cast<LDVImpl*>(pImpl)->renameRegister(OldReg, NewReg, SubIdx);
678}
679
680void
681UserValue::rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI) {
682  // Iterate over locations in reverse makes it easier to handle coalescing.
683  for (unsigned i = locations.size(); i ; --i) {
684    unsigned LocNo = i-1;
685    MachineOperand &Loc = locations[LocNo];
686    // Only virtual registers are rewritten.
687    if (!Loc.isReg() || !Loc.getReg() ||
688        !TargetRegisterInfo::isVirtualRegister(Loc.getReg()))
689      continue;
690    unsigned VirtReg = Loc.getReg();
691    if (VRM.isAssignedReg(VirtReg) &&
692        TargetRegisterInfo::isPhysicalRegister(VRM.getPhys(VirtReg))) {
693      Loc.substPhysReg(VRM.getPhys(VirtReg), TRI);
694    } else if (VRM.getStackSlot(VirtReg) != VirtRegMap::NO_STACK_SLOT &&
695               VRM.isSpillSlotUsed(VRM.getStackSlot(VirtReg))) {
696      // FIXME: Translate SubIdx to a stackslot offset.
697      Loc = MachineOperand::CreateFI(VRM.getStackSlot(VirtReg));
698    } else {
699      Loc.setReg(0);
700      Loc.setSubReg(0);
701    }
702    coalesceLocation(LocNo);
703  }
704  DEBUG(print(dbgs(), &TRI));
705}
706
707/// findInsertLocation - Find an iterator for inserting a DBG_VALUE
708/// instruction.
709static MachineBasicBlock::iterator
710findInsertLocation(MachineBasicBlock *MBB, SlotIndex Idx,
711                   LiveIntervals &LIS) {
712  SlotIndex Start = LIS.getMBBStartIdx(MBB);
713  Idx = Idx.getBaseIndex();
714
715  // Try to find an insert location by going backwards from Idx.
716  MachineInstr *MI;
717  while (!(MI = LIS.getInstructionFromIndex(Idx))) {
718    // We've reached the beginning of MBB.
719    if (Idx == Start) {
720      MachineBasicBlock::iterator I = MBB->SkipPHIsAndLabels(MBB->begin());
721      return I;
722    }
723    Idx = Idx.getPrevIndex();
724  }
725
726  // Don't insert anything after the first terminator, though.
727  return MI->getDesc().isTerminator() ? MBB->getFirstTerminator() :
728                                    llvm::next(MachineBasicBlock::iterator(MI));
729}
730
731DebugLoc UserValue::findDebugLoc() {
732  DebugLoc D = dl;
733  dl = DebugLoc();
734  return D;
735}
736void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx,
737                                 unsigned LocNo,
738                                 LiveIntervals &LIS,
739                                 const TargetInstrInfo &TII) {
740  MachineBasicBlock::iterator I = findInsertLocation(MBB, Idx, LIS);
741  MachineOperand &Loc = locations[LocNo];
742
743  // Frame index locations may require a target callback.
744  if (Loc.isFI()) {
745    MachineInstr *MI = TII.emitFrameIndexDebugValue(*MBB->getParent(),
746                                          Loc.getIndex(), offset, variable,
747                                                    findDebugLoc());
748    if (MI) {
749      MBB->insert(I, MI);
750      return;
751    }
752  }
753  // This is not a frame index, or the target is happy with a standard FI.
754  BuildMI(*MBB, I, findDebugLoc(), TII.get(TargetOpcode::DBG_VALUE))
755    .addOperand(Loc).addImm(offset).addMetadata(variable);
756}
757
758void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
759                                const TargetInstrInfo &TII) {
760  MachineFunction::iterator MFEnd = VRM->getMachineFunction().end();
761
762  for (LocMap::const_iterator I = locInts.begin(); I.valid();) {
763    SlotIndex Start = I.start();
764    SlotIndex Stop = I.stop();
765    unsigned LocNo = I.value();
766    DEBUG(dbgs() << "\t[" << Start << ';' << Stop << "):" << LocNo);
767    MachineFunction::iterator MBB = LIS.getMBBFromIndex(Start);
768    SlotIndex MBBEnd = LIS.getMBBEndIdx(MBB);
769
770    DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
771    insertDebugValue(MBB, Start, LocNo, LIS, TII);
772
773    // This interval may span multiple basic blocks.
774    // Insert a DBG_VALUE into each one.
775    while(Stop > MBBEnd) {
776      // Move to the next block.
777      Start = MBBEnd;
778      if (++MBB == MFEnd)
779        break;
780      MBBEnd = LIS.getMBBEndIdx(MBB);
781      DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
782      insertDebugValue(MBB, Start, LocNo, LIS, TII);
783    }
784    DEBUG(dbgs() << '\n');
785    if (MBB == MFEnd)
786      break;
787
788    ++I;
789  }
790}
791
792void LDVImpl::emitDebugValues(VirtRegMap *VRM) {
793  DEBUG(dbgs() << "********** EMITTING LIVE DEBUG VARIABLES **********\n");
794  const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
795  for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
796    userValues[i]->rewriteLocations(*VRM, *TRI);
797    userValues[i]->emitDebugValues(VRM, *LIS, *TII);
798  }
799}
800
801void LiveDebugVariables::emitDebugValues(VirtRegMap *VRM) {
802  if (pImpl)
803    static_cast<LDVImpl*>(pImpl)->emitDebugValues(VRM);
804}
805
806
807#ifndef NDEBUG
808void LiveDebugVariables::dump() {
809  if (pImpl)
810    static_cast<LDVImpl*>(pImpl)->print(dbgs());
811}
812#endif
813
814