LiveDebugVariables.cpp revision 2debd48ca790ac01be6e12e094fdf4fdcadc8364 
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/Analysis/DebugInfo.h"
29#include "llvm/ADT/IntervalMap.h"
30#include "llvm/ADT/Statistic.h"
31#include "llvm/CodeGen/LexicalScopes.h"
32#include "llvm/CodeGen/LiveIntervalAnalysis.h"
33#include "llvm/CodeGen/MachineDominators.h"
34#include "llvm/CodeGen/MachineFunction.h"
35#include "llvm/CodeGen/MachineInstrBuilder.h"
36#include "llvm/CodeGen/MachineRegisterInfo.h"
37#include "llvm/CodeGen/Passes.h"
38#include "llvm/Support/CommandLine.h"
39#include "llvm/Support/Debug.h"
40#include "llvm/Target/TargetInstrInfo.h"
41#include "llvm/Target/TargetMachine.h"
42#include "llvm/Target/TargetRegisterInfo.h"
43
44using namespace llvm;
45
46static cl::opt<bool>
47EnableLDV("live-debug-variables", cl::init(true),
48          cl::desc("Enable the live debug variables pass"), cl::Hidden);
49
50STATISTIC(NumInsertedDebugValues, "Number of DBG_VALUEs inserted");
51char LiveDebugVariables::ID = 0;
52
53INITIALIZE_PASS_BEGIN(LiveDebugVariables, "livedebugvars",
54                "Debug Variable Analysis", false, false)
55INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
56INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
57INITIALIZE_PASS_END(LiveDebugVariables, "livedebugvars",
58                "Debug Variable Analysis", false, false)
59
60void LiveDebugVariables::getAnalysisUsage(AnalysisUsage &AU) const {
61  AU.addRequired<MachineDominatorTree>();
62  AU.addRequiredTransitive<LiveIntervals>();
63  AU.setPreservesAll();
64  MachineFunctionPass::getAnalysisUsage(AU);
65}
66
67LiveDebugVariables::LiveDebugVariables() : MachineFunctionPass(ID), pImpl(0) {
68  initializeLiveDebugVariablesPass(*PassRegistry::getPassRegistry());
69}
70
71/// LocMap - Map of where a user value is live, and its location.
72typedef IntervalMap<SlotIndex, unsigned, 4> LocMap;
73
74namespace {
75/// UserValueScopes - Keeps track of lexical scopes associated with an
76/// user value's source location.
77class UserValueScopes {
78  DebugLoc DL;
79  LexicalScopes &LS;
80  SmallPtrSet<const MachineBasicBlock *, 4> LBlocks;
81
82public:
83  UserValueScopes(DebugLoc D, LexicalScopes &L) : DL(D), LS(L) {}
84
85  /// dominates - Return true if current scope dominates at least one machine
86  /// instruction in a given machine basic block.
87  bool dominates(MachineBasicBlock *MBB) {
88    if (LBlocks.empty())
89      LS.getMachineBasicBlocks(DL, LBlocks);
90    if (LBlocks.count(MBB) != 0 || LS.dominates(DL, MBB))
91      return true;
92    return false;
93  }
94};
95} // end anonymous namespace
96
97/// UserValue - A user value is a part of a debug info user variable.
98///
99/// A DBG_VALUE instruction notes that (a sub-register of) a virtual register
100/// holds part of a user variable. The part is identified by a byte offset.
101///
102/// UserValues are grouped into equivalence classes for easier searching. Two
103/// user values are related if they refer to the same variable, or if they are
104/// held by the same virtual register. The equivalence class is the transitive
105/// closure of that relation.
106namespace {
107class LDVImpl;
108class UserValue {
109  const MDNode *variable; ///< The debug info variable we are part of.
110  unsigned offset;        ///< Byte offset into variable.
111  DebugLoc dl;            ///< The debug location for the variable. This is
112                          ///< used by dwarf writer to find lexical scope.
113  UserValue *leader;      ///< Equivalence class leader.
114  UserValue *next;        ///< Next value in equivalence class, or null.
115
116  /// Numbered locations referenced by locmap.
117  SmallVector<MachineOperand, 4> locations;
118
119  /// Map of slot indices where this value is live.
120  LocMap locInts;
121
122  /// coalesceLocation - After LocNo was changed, check if it has become
123  /// identical to another location, and coalesce them. This may cause LocNo or
124  /// a later location to be erased, but no earlier location will be erased.
125  void coalesceLocation(unsigned LocNo);
126
127  /// insertDebugValue - Insert a DBG_VALUE into MBB at Idx for LocNo.
128  void insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx, unsigned LocNo,
129                        LiveIntervals &LIS, const TargetInstrInfo &TII);
130
131  /// splitLocation - Replace OldLocNo ranges with NewRegs ranges where NewRegs
132  /// is live. Returns true if any changes were made.
133  bool splitLocation(unsigned OldLocNo, ArrayRef<LiveInterval*> NewRegs);
134
135public:
136  /// UserValue - Create a new UserValue.
137  UserValue(const MDNode *var, unsigned o, DebugLoc L,
138            LocMap::Allocator &alloc)
139    : variable(var), offset(o), dl(L), leader(this), next(0), locInts(alloc)
140  {}
141
142  /// getLeader - Get the leader of this value's equivalence class.
143  UserValue *getLeader() {
144    UserValue *l = leader;
145    while (l != l->leader)
146      l = l->leader;
147    return leader = l;
148  }
149
150  /// getNext - Return the next UserValue in the equivalence class.
151  UserValue *getNext() const { return next; }
152
153  /// match - Does this UserValue match the parameters?
154  bool match(const MDNode *Var, unsigned Offset) const {
155    return Var == variable && Offset == offset;
156  }
157
158  /// merge - Merge equivalence classes.
159  static UserValue *merge(UserValue *L1, UserValue *L2) {
160    L2 = L2->getLeader();
161    if (!L1)
162      return L2;
163    L1 = L1->getLeader();
164    if (L1 == L2)
165      return L1;
166    // Splice L2 before L1's members.
167    UserValue *End = L2;
168    while (End->next)
169      End->leader = L1, End = End->next;
170    End->leader = L1;
171    End->next = L1->next;
172    L1->next = L2;
173    return L1;
174  }
175
176  /// getLocationNo - Return the location number that matches Loc.
177  unsigned getLocationNo(const MachineOperand &LocMO) {
178    if (LocMO.isReg()) {
179      if (LocMO.getReg() == 0)
180        return ~0u;
181      // For register locations we dont care about use/def and other flags.
182      for (unsigned i = 0, e = locations.size(); i != e; ++i)
183        if (locations[i].isReg() &&
184            locations[i].getReg() == LocMO.getReg() &&
185            locations[i].getSubReg() == LocMO.getSubReg())
186          return i;
187    } else
188      for (unsigned i = 0, e = locations.size(); i != e; ++i)
189        if (LocMO.isIdenticalTo(locations[i]))
190          return i;
191    locations.push_back(LocMO);
192    // We are storing a MachineOperand outside a MachineInstr.
193    locations.back().clearParent();
194    // Don't store def operands.
195    if (locations.back().isReg())
196      locations.back().setIsUse();
197    return locations.size() - 1;
198  }
199
200  /// mapVirtRegs - Ensure that all virtual register locations are mapped.
201  void mapVirtRegs(LDVImpl *LDV);
202
203  /// addDef - Add a definition point to this value.
204  void addDef(SlotIndex Idx, const MachineOperand &LocMO) {
205    // Add a singular (Idx,Idx) -> Loc mapping.
206    LocMap::iterator I = locInts.find(Idx);
207    if (!I.valid() || I.start() != Idx)
208      I.insert(Idx, Idx.getNextSlot(), getLocationNo(LocMO));
209    else
210      // A later DBG_VALUE at the same SlotIndex overrides the old location.
211      I.setValue(getLocationNo(LocMO));
212  }
213
214  /// extendDef - Extend the current definition as far as possible down the
215  /// dominator tree. Stop when meeting an existing def or when leaving the live
216  /// range of VNI.
217  /// End points where VNI is no longer live are added to Kills.
218  /// @param Idx   Starting point for the definition.
219  /// @param LocNo Location number to propagate.
220  /// @param LI    Restrict liveness to where LI has the value VNI. May be null.
221  /// @param VNI   When LI is not null, this is the value to restrict to.
222  /// @param Kills Append end points of VNI's live range to Kills.
223  /// @param LIS   Live intervals analysis.
224  /// @param MDT   Dominator tree.
225  void extendDef(SlotIndex Idx, unsigned LocNo,
226                 LiveInterval *LI, const VNInfo *VNI,
227                 SmallVectorImpl<SlotIndex> *Kills,
228                 LiveIntervals &LIS, MachineDominatorTree &MDT,
229		 UserValueScopes &UVS);
230
231  /// addDefsFromCopies - The value in LI/LocNo may be copies to other
232  /// registers. Determine if any of the copies are available at the kill
233  /// points, and add defs if possible.
234  /// @param LI      Scan for copies of the value in LI->reg.
235  /// @param LocNo   Location number of LI->reg.
236  /// @param Kills   Points where the range of LocNo could be extended.
237  /// @param NewDefs Append (Idx, LocNo) of inserted defs here.
238  void addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
239                      const SmallVectorImpl<SlotIndex> &Kills,
240                      SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
241                      MachineRegisterInfo &MRI,
242                      LiveIntervals &LIS);
243
244  /// computeIntervals - Compute the live intervals of all locations after
245  /// collecting all their def points.
246  void computeIntervals(MachineRegisterInfo &MRI,
247                        LiveIntervals &LIS, MachineDominatorTree &MDT,
248                        UserValueScopes &UVS);
249
250  /// renameRegister - Update locations to rewrite OldReg as NewReg:SubIdx.
251  void renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx,
252                      const TargetRegisterInfo *TRI);
253
254  /// splitRegister - Replace OldReg ranges with NewRegs ranges where NewRegs is
255  /// live. Returns true if any changes were made.
256  bool splitRegister(unsigned OldLocNo, ArrayRef<LiveInterval*> NewRegs);
257
258  /// rewriteLocations - Rewrite virtual register locations according to the
259  /// provided virtual register map.
260  void rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI);
261
262  /// emitDebugVariables - Recreate DBG_VALUE instruction from data structures.
263  void emitDebugValues(VirtRegMap *VRM,
264                       LiveIntervals &LIS, const TargetInstrInfo &TRI);
265
266  /// findDebugLoc - Return DebugLoc used for this DBG_VALUE instruction. A
267  /// variable may have more than one corresponding DBG_VALUE instructions.
268  /// Only first one needs DebugLoc to identify variable's lexical scope
269  /// in source file.
270  DebugLoc findDebugLoc();
271
272  /// getDebugLoc - Return DebugLoc of this UserValue.
273  DebugLoc getDebugLoc() { return dl;}
274  void print(raw_ostream&, const TargetMachine*);
275};
276} // namespace
277
278/// LDVImpl - Implementation of the LiveDebugVariables pass.
279namespace {
280class LDVImpl {
281  LiveDebugVariables &pass;
282  LocMap::Allocator allocator;
283  MachineFunction *MF;
284  LiveIntervals *LIS;
285  LexicalScopes LS;
286  MachineDominatorTree *MDT;
287  const TargetRegisterInfo *TRI;
288
289  /// userValues - All allocated UserValue instances.
290  SmallVector<UserValue*, 8> userValues;
291
292  /// Map virtual register to eq class leader.
293  typedef DenseMap<unsigned, UserValue*> VRMap;
294  VRMap virtRegToEqClass;
295
296  /// Map user variable to eq class leader.
297  typedef DenseMap<const MDNode *, UserValue*> UVMap;
298  UVMap userVarMap;
299
300  /// getUserValue - Find or create a UserValue.
301  UserValue *getUserValue(const MDNode *Var, unsigned Offset, DebugLoc DL);
302
303  /// lookupVirtReg - Find the EC leader for VirtReg or null.
304  UserValue *lookupVirtReg(unsigned VirtReg);
305
306  /// handleDebugValue - Add DBG_VALUE instruction to our maps.
307  /// @param MI  DBG_VALUE instruction
308  /// @param Idx Last valid SLotIndex before instruction.
309  /// @return    True if the DBG_VALUE instruction should be deleted.
310  bool handleDebugValue(MachineInstr *MI, SlotIndex Idx);
311
312  /// collectDebugValues - Collect and erase all DBG_VALUE instructions, adding
313  /// a UserValue def for each instruction.
314  /// @param mf MachineFunction to be scanned.
315  /// @return True if any debug values were found.
316  bool collectDebugValues(MachineFunction &mf);
317
318  /// computeIntervals - Compute the live intervals of all user values after
319  /// collecting all their def points.
320  void computeIntervals();
321
322public:
323  LDVImpl(LiveDebugVariables *ps) : pass(*ps) {}
324  bool runOnMachineFunction(MachineFunction &mf);
325
326  /// clear - Relase all memory.
327  void clear() {
328    DeleteContainerPointers(userValues);
329    userValues.clear();
330    virtRegToEqClass.clear();
331    userVarMap.clear();
332  }
333
334  /// mapVirtReg - Map virtual register to an equivalence class.
335  void mapVirtReg(unsigned VirtReg, UserValue *EC);
336
337  /// renameRegister - Replace all references to OldReg with NewReg:SubIdx.
338  void renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx);
339
340  /// splitRegister -  Replace all references to OldReg with NewRegs.
341  void splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs);
342
343  /// emitDebugVariables - Recreate DBG_VALUE instruction from data structures.
344  void emitDebugValues(VirtRegMap *VRM);
345
346  void print(raw_ostream&);
347};
348} // namespace
349
350void UserValue::print(raw_ostream &OS, const TargetMachine *TM) {
351  DIVariable DV(variable);
352  OS << "!\"";
353  DV.printExtendedName(OS);
354  OS << "\"\t";
355  if (offset)
356    OS << '+' << offset;
357  for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) {
358    OS << " [" << I.start() << ';' << I.stop() << "):";
359    if (I.value() == ~0u)
360      OS << "undef";
361    else
362      OS << I.value();
363  }
364  for (unsigned i = 0, e = locations.size(); i != e; ++i) {
365    OS << " Loc" << i << '=';
366    locations[i].print(OS, TM);
367  }
368  OS << '\n';
369}
370
371void LDVImpl::print(raw_ostream &OS) {
372  OS << "********** DEBUG VARIABLES **********\n";
373  for (unsigned i = 0, e = userValues.size(); i != e; ++i)
374    userValues[i]->print(OS, &MF->getTarget());
375}
376
377void UserValue::coalesceLocation(unsigned LocNo) {
378  unsigned KeepLoc = 0;
379  for (unsigned e = locations.size(); KeepLoc != e; ++KeepLoc) {
380    if (KeepLoc == LocNo)
381      continue;
382    if (locations[KeepLoc].isIdenticalTo(locations[LocNo]))
383      break;
384  }
385  // No matches.
386  if (KeepLoc == locations.size())
387    return;
388
389  // Keep the smaller location, erase the larger one.
390  unsigned EraseLoc = LocNo;
391  if (KeepLoc > EraseLoc)
392    std::swap(KeepLoc, EraseLoc);
393  locations.erase(locations.begin() + EraseLoc);
394
395  // Rewrite values.
396  for (LocMap::iterator I = locInts.begin(); I.valid(); ++I) {
397    unsigned v = I.value();
398    if (v == EraseLoc)
399      I.setValue(KeepLoc);      // Coalesce when possible.
400    else if (v > EraseLoc)
401      I.setValueUnchecked(v-1); // Avoid coalescing with untransformed values.
402  }
403}
404
405void UserValue::mapVirtRegs(LDVImpl *LDV) {
406  for (unsigned i = 0, e = locations.size(); i != e; ++i)
407    if (locations[i].isReg() &&
408        TargetRegisterInfo::isVirtualRegister(locations[i].getReg()))
409      LDV->mapVirtReg(locations[i].getReg(), this);
410}
411
412UserValue *LDVImpl::getUserValue(const MDNode *Var, unsigned Offset,
413                                 DebugLoc DL) {
414  UserValue *&Leader = userVarMap[Var];
415  if (Leader) {
416    UserValue *UV = Leader->getLeader();
417    Leader = UV;
418    for (; UV; UV = UV->getNext())
419      if (UV->match(Var, Offset))
420        return UV;
421  }
422
423  UserValue *UV = new UserValue(Var, Offset, DL, allocator);
424  userValues.push_back(UV);
425  Leader = UserValue::merge(Leader, UV);
426  return UV;
427}
428
429void LDVImpl::mapVirtReg(unsigned VirtReg, UserValue *EC) {
430  assert(TargetRegisterInfo::isVirtualRegister(VirtReg) && "Only map VirtRegs");
431  UserValue *&Leader = virtRegToEqClass[VirtReg];
432  Leader = UserValue::merge(Leader, EC);
433}
434
435UserValue *LDVImpl::lookupVirtReg(unsigned VirtReg) {
436  if (UserValue *UV = virtRegToEqClass.lookup(VirtReg))
437    return UV->getLeader();
438  return 0;
439}
440
441bool LDVImpl::handleDebugValue(MachineInstr *MI, SlotIndex Idx) {
442  // DBG_VALUE loc, offset, variable
443  if (MI->getNumOperands() != 3 ||
444      !MI->getOperand(1).isImm() || !MI->getOperand(2).isMetadata()) {
445    DEBUG(dbgs() << "Can't handle " << *MI);
446    return false;
447  }
448
449  // Get or create the UserValue for (variable,offset).
450  unsigned Offset = MI->getOperand(1).getImm();
451  const MDNode *Var = MI->getOperand(2).getMetadata();
452  UserValue *UV = getUserValue(Var, Offset, MI->getDebugLoc());
453  UV->addDef(Idx, MI->getOperand(0));
454  return true;
455}
456
457bool LDVImpl::collectDebugValues(MachineFunction &mf) {
458  bool Changed = false;
459  for (MachineFunction::iterator MFI = mf.begin(), MFE = mf.end(); MFI != MFE;
460       ++MFI) {
461    MachineBasicBlock *MBB = MFI;
462    for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
463         MBBI != MBBE;) {
464      if (!MBBI->isDebugValue()) {
465        ++MBBI;
466        continue;
467      }
468      // DBG_VALUE has no slot index, use the previous instruction instead.
469      SlotIndex Idx = MBBI == MBB->begin() ?
470        LIS->getMBBStartIdx(MBB) :
471        LIS->getInstructionIndex(llvm::prior(MBBI)).getRegSlot();
472      // Handle consecutive DBG_VALUE instructions with the same slot index.
473      do {
474        if (handleDebugValue(MBBI, Idx)) {
475          MBBI = MBB->erase(MBBI);
476          Changed = true;
477        } else
478          ++MBBI;
479      } while (MBBI != MBBE && MBBI->isDebugValue());
480    }
481  }
482  return Changed;
483}
484
485void UserValue::extendDef(SlotIndex Idx, unsigned LocNo,
486                          LiveInterval *LI, const VNInfo *VNI,
487                          SmallVectorImpl<SlotIndex> *Kills,
488                          LiveIntervals &LIS, MachineDominatorTree &MDT,
489			  UserValueScopes &UVS) {
490  SmallVector<SlotIndex, 16> Todo;
491  Todo.push_back(Idx);
492  do {
493    SlotIndex Start = Todo.pop_back_val();
494    MachineBasicBlock *MBB = LIS.getMBBFromIndex(Start);
495    SlotIndex Stop = LIS.getMBBEndIdx(MBB);
496    LocMap::iterator I = locInts.find(Start);
497
498    // Limit to VNI's live range.
499    bool ToEnd = true;
500    if (LI && VNI) {
501      LiveRange *Range = LI->getLiveRangeContaining(Start);
502      if (!Range || Range->valno != VNI) {
503        if (Kills)
504          Kills->push_back(Start);
505        continue;
506      }
507      if (Range->end < Stop)
508        Stop = Range->end, ToEnd = false;
509    }
510
511    // There could already be a short def at Start.
512    if (I.valid() && I.start() <= Start) {
513      // Stop when meeting a different location or an already extended interval.
514      Start = Start.getNextSlot();
515      if (I.value() != LocNo || I.stop() != Start)
516        continue;
517      // This is a one-slot placeholder. Just skip it.
518      ++I;
519    }
520
521    // Limited by the next def.
522    if (I.valid() && I.start() < Stop)
523      Stop = I.start(), ToEnd = false;
524    // Limited by VNI's live range.
525    else if (!ToEnd && Kills)
526      Kills->push_back(Stop);
527
528    if (Start >= Stop)
529      continue;
530
531    I.insert(Start, Stop, LocNo);
532
533    // If we extended to the MBB end, propagate down the dominator tree.
534    if (!ToEnd)
535      continue;
536    const std::vector<MachineDomTreeNode*> &Children =
537      MDT.getNode(MBB)->getChildren();
538    for (unsigned i = 0, e = Children.size(); i != e; ++i) {
539      MachineBasicBlock *MBB = Children[i]->getBlock();
540      if (UVS.dominates(MBB))
541        Todo.push_back(LIS.getMBBStartIdx(MBB));
542    }
543  } while (!Todo.empty());
544}
545
546void
547UserValue::addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
548                      const SmallVectorImpl<SlotIndex> &Kills,
549                      SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
550                      MachineRegisterInfo &MRI, LiveIntervals &LIS) {
551  if (Kills.empty())
552    return;
553  // Don't track copies from physregs, there are too many uses.
554  if (!TargetRegisterInfo::isVirtualRegister(LI->reg))
555    return;
556
557  // Collect all the (vreg, valno) pairs that are copies of LI.
558  SmallVector<std::pair<LiveInterval*, const VNInfo*>, 8> CopyValues;
559  for (MachineRegisterInfo::use_nodbg_iterator
560         UI = MRI.use_nodbg_begin(LI->reg),
561         UE = MRI.use_nodbg_end(); UI != UE; ++UI) {
562    // Copies of the full value.
563    if (UI.getOperand().getSubReg() || !UI->isCopy())
564      continue;
565    MachineInstr *MI = &*UI;
566    unsigned DstReg = MI->getOperand(0).getReg();
567
568    // Don't follow copies to physregs. These are usually setting up call
569    // arguments, and the argument registers are always call clobbered. We are
570    // better off in the source register which could be a callee-saved register,
571    // or it could be spilled.
572    if (!TargetRegisterInfo::isVirtualRegister(DstReg))
573      continue;
574
575    // Is LocNo extended to reach this copy? If not, another def may be blocking
576    // it, or we are looking at a wrong value of LI.
577    SlotIndex Idx = LIS.getInstructionIndex(MI);
578    LocMap::iterator I = locInts.find(Idx.getRegSlot(true));
579    if (!I.valid() || I.value() != LocNo)
580      continue;
581
582    if (!LIS.hasInterval(DstReg))
583      continue;
584    LiveInterval *DstLI = &LIS.getInterval(DstReg);
585    const VNInfo *DstVNI = DstLI->getVNInfoAt(Idx.getRegSlot());
586    assert(DstVNI && DstVNI->def == Idx.getRegSlot() && "Bad copy value");
587    CopyValues.push_back(std::make_pair(DstLI, DstVNI));
588  }
589
590  if (CopyValues.empty())
591    return;
592
593  DEBUG(dbgs() << "Got " << CopyValues.size() << " copies of " << *LI << '\n');
594
595  // Try to add defs of the copied values for each kill point.
596  for (unsigned i = 0, e = Kills.size(); i != e; ++i) {
597    SlotIndex Idx = Kills[i];
598    for (unsigned j = 0, e = CopyValues.size(); j != e; ++j) {
599      LiveInterval *DstLI = CopyValues[j].first;
600      const VNInfo *DstVNI = CopyValues[j].second;
601      if (DstLI->getVNInfoAt(Idx) != DstVNI)
602        continue;
603      // Check that there isn't already a def at Idx
604      LocMap::iterator I = locInts.find(Idx);
605      if (I.valid() && I.start() <= Idx)
606        continue;
607      DEBUG(dbgs() << "Kill at " << Idx << " covered by valno #"
608                   << DstVNI->id << " in " << *DstLI << '\n');
609      MachineInstr *CopyMI = LIS.getInstructionFromIndex(DstVNI->def);
610      assert(CopyMI && CopyMI->isCopy() && "Bad copy value");
611      unsigned LocNo = getLocationNo(CopyMI->getOperand(0));
612      I.insert(Idx, Idx.getNextSlot(), LocNo);
613      NewDefs.push_back(std::make_pair(Idx, LocNo));
614      break;
615    }
616  }
617}
618
619void
620UserValue::computeIntervals(MachineRegisterInfo &MRI,
621                            LiveIntervals &LIS,
622                            MachineDominatorTree &MDT,
623			    UserValueScopes &UVS) {
624  SmallVector<std::pair<SlotIndex, unsigned>, 16> Defs;
625
626  // Collect all defs to be extended (Skipping undefs).
627  for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I)
628    if (I.value() != ~0u)
629      Defs.push_back(std::make_pair(I.start(), I.value()));
630
631  // Extend all defs, and possibly add new ones along the way.
632  for (unsigned i = 0; i != Defs.size(); ++i) {
633    SlotIndex Idx = Defs[i].first;
634    unsigned LocNo = Defs[i].second;
635    const MachineOperand &Loc = locations[LocNo];
636
637    // Register locations are constrained to where the register value is live.
638    if (Loc.isReg() && LIS.hasInterval(Loc.getReg())) {
639      LiveInterval *LI = &LIS.getInterval(Loc.getReg());
640      const VNInfo *VNI = LI->getVNInfoAt(Idx);
641      SmallVector<SlotIndex, 16> Kills;
642      extendDef(Idx, LocNo, LI, VNI, &Kills, LIS, MDT, UVS);
643      addDefsFromCopies(LI, LocNo, Kills, Defs, MRI, LIS);
644    } else
645      extendDef(Idx, LocNo, 0, 0, 0, LIS, MDT, UVS);
646  }
647
648  // Finally, erase all the undefs.
649  for (LocMap::iterator I = locInts.begin(); I.valid();)
650    if (I.value() == ~0u)
651      I.erase();
652    else
653      ++I;
654}
655
656void LDVImpl::computeIntervals() {
657  for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
658    UserValueScopes UVS(userValues[i]->getDebugLoc(), LS);
659    userValues[i]->computeIntervals(MF->getRegInfo(), *LIS, *MDT, UVS);
660    userValues[i]->mapVirtRegs(this);
661  }
662}
663
664bool LDVImpl::runOnMachineFunction(MachineFunction &mf) {
665  MF = &mf;
666  LIS = &pass.getAnalysis<LiveIntervals>();
667  MDT = &pass.getAnalysis<MachineDominatorTree>();
668  TRI = mf.getTarget().getRegisterInfo();
669  clear();
670  LS.initialize(mf);
671  DEBUG(dbgs() << "********** COMPUTING LIVE DEBUG VARIABLES: "
672               << ((Value*)mf.getFunction())->getName()
673               << " **********\n");
674
675  bool Changed = collectDebugValues(mf);
676  computeIntervals();
677  DEBUG(print(dbgs()));
678  LS.releaseMemory();
679  return Changed;
680}
681
682bool LiveDebugVariables::runOnMachineFunction(MachineFunction &mf) {
683  if (!EnableLDV)
684    return false;
685  if (!pImpl)
686    pImpl = new LDVImpl(this);
687  return static_cast<LDVImpl*>(pImpl)->runOnMachineFunction(mf);
688}
689
690void LiveDebugVariables::releaseMemory() {
691  if (pImpl)
692    static_cast<LDVImpl*>(pImpl)->clear();
693}
694
695LiveDebugVariables::~LiveDebugVariables() {
696  if (pImpl)
697    delete static_cast<LDVImpl*>(pImpl);
698}
699
700void UserValue::
701renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx,
702               const TargetRegisterInfo *TRI) {
703  for (unsigned i = locations.size(); i; --i) {
704    unsigned LocNo = i - 1;
705    MachineOperand &Loc = locations[LocNo];
706    if (!Loc.isReg() || Loc.getReg() != OldReg)
707      continue;
708    if (TargetRegisterInfo::isPhysicalRegister(NewReg))
709      Loc.substPhysReg(NewReg, *TRI);
710    else
711      Loc.substVirtReg(NewReg, SubIdx, *TRI);
712    coalesceLocation(LocNo);
713  }
714}
715
716void LDVImpl::
717renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx) {
718  UserValue *UV = lookupVirtReg(OldReg);
719  if (!UV)
720    return;
721
722  if (TargetRegisterInfo::isVirtualRegister(NewReg))
723    mapVirtReg(NewReg, UV);
724  virtRegToEqClass.erase(OldReg);
725
726  do {
727    UV->renameRegister(OldReg, NewReg, SubIdx, TRI);
728    UV = UV->getNext();
729  } while (UV);
730}
731
732void LiveDebugVariables::
733renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx) {
734  if (pImpl)
735    static_cast<LDVImpl*>(pImpl)->renameRegister(OldReg, NewReg, SubIdx);
736}
737
738//===----------------------------------------------------------------------===//
739//                           Live Range Splitting
740//===----------------------------------------------------------------------===//
741
742bool
743UserValue::splitLocation(unsigned OldLocNo, ArrayRef<LiveInterval*> NewRegs) {
744  DEBUG({
745    dbgs() << "Splitting Loc" << OldLocNo << '\t';
746    print(dbgs(), 0);
747  });
748  bool DidChange = false;
749  LocMap::iterator LocMapI;
750  LocMapI.setMap(locInts);
751  for (unsigned i = 0; i != NewRegs.size(); ++i) {
752    LiveInterval *LI = NewRegs[i];
753    if (LI->empty())
754      continue;
755
756    // Don't allocate the new LocNo until it is needed.
757    unsigned NewLocNo = ~0u;
758
759    // Iterate over the overlaps between locInts and LI.
760    LocMapI.find(LI->beginIndex());
761    if (!LocMapI.valid())
762      continue;
763    LiveInterval::iterator LII = LI->advanceTo(LI->begin(), LocMapI.start());
764    LiveInterval::iterator LIE = LI->end();
765    while (LocMapI.valid() && LII != LIE) {
766      // At this point, we know that LocMapI.stop() > LII->start.
767      LII = LI->advanceTo(LII, LocMapI.start());
768      if (LII == LIE)
769        break;
770
771      // Now LII->end > LocMapI.start(). Do we have an overlap?
772      if (LocMapI.value() == OldLocNo && LII->start < LocMapI.stop()) {
773        // Overlapping correct location. Allocate NewLocNo now.
774        if (NewLocNo == ~0u) {
775          MachineOperand MO = MachineOperand::CreateReg(LI->reg, false);
776          MO.setSubReg(locations[OldLocNo].getSubReg());
777          NewLocNo = getLocationNo(MO);
778          DidChange = true;
779        }
780
781        SlotIndex LStart = LocMapI.start();
782        SlotIndex LStop  = LocMapI.stop();
783
784        // Trim LocMapI down to the LII overlap.
785        if (LStart < LII->start)
786          LocMapI.setStartUnchecked(LII->start);
787        if (LStop > LII->end)
788          LocMapI.setStopUnchecked(LII->end);
789
790        // Change the value in the overlap. This may trigger coalescing.
791        LocMapI.setValue(NewLocNo);
792
793        // Re-insert any removed OldLocNo ranges.
794        if (LStart < LocMapI.start()) {
795          LocMapI.insert(LStart, LocMapI.start(), OldLocNo);
796          ++LocMapI;
797          assert(LocMapI.valid() && "Unexpected coalescing");
798        }
799        if (LStop > LocMapI.stop()) {
800          ++LocMapI;
801          LocMapI.insert(LII->end, LStop, OldLocNo);
802          --LocMapI;
803        }
804      }
805
806      // Advance to the next overlap.
807      if (LII->end < LocMapI.stop()) {
808        if (++LII == LIE)
809          break;
810        LocMapI.advanceTo(LII->start);
811      } else {
812        ++LocMapI;
813        if (!LocMapI.valid())
814          break;
815        LII = LI->advanceTo(LII, LocMapI.start());
816      }
817    }
818  }
819
820  // Finally, remove any remaining OldLocNo intervals and OldLocNo itself.
821  locations.erase(locations.begin() + OldLocNo);
822  LocMapI.goToBegin();
823  while (LocMapI.valid()) {
824    unsigned v = LocMapI.value();
825    if (v == OldLocNo) {
826      DEBUG(dbgs() << "Erasing [" << LocMapI.start() << ';'
827                   << LocMapI.stop() << ")\n");
828      LocMapI.erase();
829    } else {
830      if (v > OldLocNo)
831        LocMapI.setValueUnchecked(v-1);
832      ++LocMapI;
833    }
834  }
835
836  DEBUG({dbgs() << "Split result: \t"; print(dbgs(), 0);});
837  return DidChange;
838}
839
840bool
841UserValue::splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs) {
842  bool DidChange = false;
843  // Split locations referring to OldReg. Iterate backwards so splitLocation can
844  // safely erase unuused locations.
845  for (unsigned i = locations.size(); i ; --i) {
846    unsigned LocNo = i-1;
847    const MachineOperand *Loc = &locations[LocNo];
848    if (!Loc->isReg() || Loc->getReg() != OldReg)
849      continue;
850    DidChange |= splitLocation(LocNo, NewRegs);
851  }
852  return DidChange;
853}
854
855void LDVImpl::splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs) {
856  bool DidChange = false;
857  for (UserValue *UV = lookupVirtReg(OldReg); UV; UV = UV->getNext())
858    DidChange |= UV->splitRegister(OldReg, NewRegs);
859
860  if (!DidChange)
861    return;
862
863  // Map all of the new virtual registers.
864  UserValue *UV = lookupVirtReg(OldReg);
865  for (unsigned i = 0; i != NewRegs.size(); ++i)
866    mapVirtReg(NewRegs[i]->reg, UV);
867}
868
869void LiveDebugVariables::
870splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs) {
871  if (pImpl)
872    static_cast<LDVImpl*>(pImpl)->splitRegister(OldReg, NewRegs);
873}
874
875void
876UserValue::rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI) {
877  // Iterate over locations in reverse makes it easier to handle coalescing.
878  for (unsigned i = locations.size(); i ; --i) {
879    unsigned LocNo = i-1;
880    MachineOperand &Loc = locations[LocNo];
881    // Only virtual registers are rewritten.
882    if (!Loc.isReg() || !Loc.getReg() ||
883        !TargetRegisterInfo::isVirtualRegister(Loc.getReg()))
884      continue;
885    unsigned VirtReg = Loc.getReg();
886    if (VRM.isAssignedReg(VirtReg) &&
887        TargetRegisterInfo::isPhysicalRegister(VRM.getPhys(VirtReg))) {
888      // This can create a %noreg operand in rare cases when the sub-register
889      // index is no longer available. That means the user value is in a
890      // non-existent sub-register, and %noreg is exactly what we want.
891      Loc.substPhysReg(VRM.getPhys(VirtReg), TRI);
892    } else if (VRM.getStackSlot(VirtReg) != VirtRegMap::NO_STACK_SLOT) {
893      // FIXME: Translate SubIdx to a stackslot offset.
894      Loc = MachineOperand::CreateFI(VRM.getStackSlot(VirtReg));
895    } else {
896      Loc.setReg(0);
897      Loc.setSubReg(0);
898    }
899    coalesceLocation(LocNo);
900  }
901}
902
903/// findInsertLocation - Find an iterator for inserting a DBG_VALUE
904/// instruction.
905static MachineBasicBlock::iterator
906findInsertLocation(MachineBasicBlock *MBB, SlotIndex Idx,
907                   LiveIntervals &LIS) {
908  SlotIndex Start = LIS.getMBBStartIdx(MBB);
909  Idx = Idx.getBaseIndex();
910
911  // Try to find an insert location by going backwards from Idx.
912  MachineInstr *MI;
913  while (!(MI = LIS.getInstructionFromIndex(Idx))) {
914    // We've reached the beginning of MBB.
915    if (Idx == Start) {
916      MachineBasicBlock::iterator I = MBB->SkipPHIsAndLabels(MBB->begin());
917      return I;
918    }
919    Idx = Idx.getPrevIndex();
920  }
921
922  // Don't insert anything after the first terminator, though.
923  return MI->getDesc().isTerminator() ? MBB->getFirstTerminator() :
924                                    llvm::next(MachineBasicBlock::iterator(MI));
925}
926
927DebugLoc UserValue::findDebugLoc() {
928  DebugLoc D = dl;
929  dl = DebugLoc();
930  return D;
931}
932void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx,
933                                 unsigned LocNo,
934                                 LiveIntervals &LIS,
935                                 const TargetInstrInfo &TII) {
936  MachineBasicBlock::iterator I = findInsertLocation(MBB, Idx, LIS);
937  MachineOperand &Loc = locations[LocNo];
938  ++NumInsertedDebugValues;
939
940  // Frame index locations may require a target callback.
941  if (Loc.isFI()) {
942    MachineInstr *MI = TII.emitFrameIndexDebugValue(*MBB->getParent(),
943                                          Loc.getIndex(), offset, variable,
944                                                    findDebugLoc());
945    if (MI) {
946      MBB->insert(I, MI);
947      return;
948    }
949  }
950  // This is not a frame index, or the target is happy with a standard FI.
951  BuildMI(*MBB, I, findDebugLoc(), TII.get(TargetOpcode::DBG_VALUE))
952    .addOperand(Loc).addImm(offset).addMetadata(variable);
953}
954
955void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
956                                const TargetInstrInfo &TII) {
957  MachineFunction::iterator MFEnd = VRM->getMachineFunction().end();
958
959  for (LocMap::const_iterator I = locInts.begin(); I.valid();) {
960    SlotIndex Start = I.start();
961    SlotIndex Stop = I.stop();
962    unsigned LocNo = I.value();
963    DEBUG(dbgs() << "\t[" << Start << ';' << Stop << "):" << LocNo);
964    MachineFunction::iterator MBB = LIS.getMBBFromIndex(Start);
965    SlotIndex MBBEnd = LIS.getMBBEndIdx(MBB);
966
967    DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
968    insertDebugValue(MBB, Start, LocNo, LIS, TII);
969    // This interval may span multiple basic blocks.
970    // Insert a DBG_VALUE into each one.
971    while(Stop > MBBEnd) {
972      // Move to the next block.
973      Start = MBBEnd;
974      if (++MBB == MFEnd)
975        break;
976      MBBEnd = LIS.getMBBEndIdx(MBB);
977      DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
978      insertDebugValue(MBB, Start, LocNo, LIS, TII);
979    }
980    DEBUG(dbgs() << '\n');
981    if (MBB == MFEnd)
982      break;
983
984    ++I;
985  }
986}
987
988void LDVImpl::emitDebugValues(VirtRegMap *VRM) {
989  DEBUG(dbgs() << "********** EMITTING LIVE DEBUG VARIABLES **********\n");
990  const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
991  for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
992    DEBUG(userValues[i]->print(dbgs(), &MF->getTarget()));
993    userValues[i]->rewriteLocations(*VRM, *TRI);
994    userValues[i]->emitDebugValues(VRM, *LIS, *TII);
995  }
996}
997
998void LiveDebugVariables::emitDebugValues(VirtRegMap *VRM) {
999  if (pImpl)
1000    static_cast<LDVImpl*>(pImpl)->emitDebugValues(VRM);
1001}
1002
1003
1004#ifndef NDEBUG
1005void LiveDebugVariables::dump() {
1006  if (pImpl)
1007    static_cast<LDVImpl*>(pImpl)->print(dbgs());
1008}
1009#endif
1010
1011