LiveDebugVariables.cpp revision 4be3853fd0a0e3b37a27afe05327e638e680c463 
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 "llvm/ADT/IntervalMap.h"
25#include "llvm/ADT/Statistic.h"
26#include "llvm/CodeGen/LexicalScopes.h"
27#include "llvm/CodeGen/LiveIntervalAnalysis.h"
28#include "llvm/CodeGen/MachineDominators.h"
29#include "llvm/CodeGen/MachineFunction.h"
30#include "llvm/CodeGen/MachineInstrBuilder.h"
31#include "llvm/CodeGen/MachineRegisterInfo.h"
32#include "llvm/CodeGen/Passes.h"
33#include "llvm/CodeGen/VirtRegMap.h"
34#include "llvm/DebugInfo.h"
35#include "llvm/IR/Constants.h"
36#include "llvm/IR/Metadata.h"
37#include "llvm/IR/Value.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                                           EmitDone(false), ModifiedMF(false) {
69  initializeLiveDebugVariablesPass(*PassRegistry::getPassRegistry());
70}
71
72/// LocMap - Map of where a user value is live, and its location.
73typedef IntervalMap<SlotIndex, unsigned, 4> LocMap;
74
75namespace {
76/// UserValueScopes - Keeps track of lexical scopes associated with an
77/// user value's source location.
78class UserValueScopes {
79  DebugLoc DL;
80  LexicalScopes &LS;
81  SmallPtrSet<const MachineBasicBlock *, 4> LBlocks;
82
83public:
84  UserValueScopes(DebugLoc D, LexicalScopes &L) : DL(D), LS(L) {}
85
86  /// dominates - Return true if current scope dominates at least one machine
87  /// instruction in a given machine basic block.
88  bool dominates(MachineBasicBlock *MBB) {
89    if (LBlocks.empty())
90      LS.getMachineBasicBlocks(DL, LBlocks);
91    if (LBlocks.count(MBB) != 0 || LS.dominates(DL, MBB))
92      return true;
93    return false;
94  }
95};
96} // end anonymous namespace
97
98/// UserValue - A user value is a part of a debug info user variable.
99///
100/// A DBG_VALUE instruction notes that (a sub-register of) a virtual register
101/// holds part of a user variable. The part is identified by a byte offset.
102///
103/// UserValues are grouped into equivalence classes for easier searching. Two
104/// user values are related if they refer to the same variable, or if they are
105/// held by the same virtual register. The equivalence class is the transitive
106/// closure of that relation.
107namespace {
108class LDVImpl;
109class UserValue {
110  const MDNode *variable; ///< The debug info variable we are part of.
111  unsigned offset;        ///< Byte offset into variable.
112  DebugLoc dl;            ///< The debug location for the variable. This is
113                          ///< used by dwarf writer to find lexical scope.
114  UserValue *leader;      ///< Equivalence class leader.
115  UserValue *next;        ///< Next value in equivalence class, or null.
116
117  /// Numbered locations referenced by locmap.
118  SmallVector<MachineOperand, 4> locations;
119
120  /// Map of slot indices where this value is live.
121  LocMap locInts;
122
123  /// coalesceLocation - After LocNo was changed, check if it has become
124  /// identical to another location, and coalesce them. This may cause LocNo or
125  /// a later location to be erased, but no earlier location will be erased.
126  void coalesceLocation(unsigned LocNo);
127
128  /// insertDebugValue - Insert a DBG_VALUE into MBB at Idx for LocNo.
129  void insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx, unsigned LocNo,
130                        LiveIntervals &LIS, const TargetInstrInfo &TII);
131
132  /// splitLocation - Replace OldLocNo ranges with NewRegs ranges where NewRegs
133  /// is live. Returns true if any changes were made.
134  bool splitLocation(unsigned OldLocNo, ArrayRef<LiveInterval*> NewRegs);
135
136public:
137  /// UserValue - Create a new UserValue.
138  UserValue(const MDNode *var, unsigned o, DebugLoc L,
139            LocMap::Allocator &alloc)
140    : variable(var), offset(o), dl(L), leader(this), next(0), locInts(alloc)
141  {}
142
143  /// getLeader - Get the leader of this value's equivalence class.
144  UserValue *getLeader() {
145    UserValue *l = leader;
146    while (l != l->leader)
147      l = l->leader;
148    return leader = l;
149  }
150
151  /// getNext - Return the next UserValue in the equivalence class.
152  UserValue *getNext() const { return next; }
153
154  /// match - Does this UserValue match the parameters?
155  bool match(const MDNode *Var, unsigned Offset) const {
156    return Var == variable && Offset == offset;
157  }
158
159  /// merge - Merge equivalence classes.
160  static UserValue *merge(UserValue *L1, UserValue *L2) {
161    L2 = L2->getLeader();
162    if (!L1)
163      return L2;
164    L1 = L1->getLeader();
165    if (L1 == L2)
166      return L1;
167    // Splice L2 before L1's members.
168    UserValue *End = L2;
169    while (End->next)
170      End->leader = L1, End = End->next;
171    End->leader = L1;
172    End->next = L1->next;
173    L1->next = L2;
174    return L1;
175  }
176
177  /// getLocationNo - Return the location number that matches Loc.
178  unsigned getLocationNo(const MachineOperand &LocMO) {
179    if (LocMO.isReg()) {
180      if (LocMO.getReg() == 0)
181        return ~0u;
182      // For register locations we dont care about use/def and other flags.
183      for (unsigned i = 0, e = locations.size(); i != e; ++i)
184        if (locations[i].isReg() &&
185            locations[i].getReg() == LocMO.getReg() &&
186            locations[i].getSubReg() == LocMO.getSubReg())
187          return i;
188    } else
189      for (unsigned i = 0, e = locations.size(); i != e; ++i)
190        if (LocMO.isIdenticalTo(locations[i]))
191          return i;
192    locations.push_back(LocMO);
193    // We are storing a MachineOperand outside a MachineInstr.
194    locations.back().clearParent();
195    // Don't store def operands.
196    if (locations.back().isReg())
197      locations.back().setIsUse();
198    return locations.size() - 1;
199  }
200
201  /// mapVirtRegs - Ensure that all virtual register locations are mapped.
202  void mapVirtRegs(LDVImpl *LDV);
203
204  /// addDef - Add a definition point to this value.
205  void addDef(SlotIndex Idx, const MachineOperand &LocMO) {
206    // Add a singular (Idx,Idx) -> Loc mapping.
207    LocMap::iterator I = locInts.find(Idx);
208    if (!I.valid() || I.start() != Idx)
209      I.insert(Idx, Idx.getNextSlot(), getLocationNo(LocMO));
210    else
211      // A later DBG_VALUE at the same SlotIndex overrides the old location.
212      I.setValue(getLocationNo(LocMO));
213  }
214
215  /// extendDef - Extend the current definition as far as possible down the
216  /// dominator tree. Stop when meeting an existing def or when leaving the live
217  /// range of VNI.
218  /// End points where VNI is no longer live are added to Kills.
219  /// @param Idx   Starting point for the definition.
220  /// @param LocNo Location number to propagate.
221  /// @param LI    Restrict liveness to where LI has the value VNI. May be null.
222  /// @param VNI   When LI is not null, this is the value to restrict to.
223  /// @param Kills Append end points of VNI's live range to Kills.
224  /// @param LIS   Live intervals analysis.
225  /// @param MDT   Dominator tree.
226  void extendDef(SlotIndex Idx, unsigned LocNo,
227                 LiveInterval *LI, const VNInfo *VNI,
228                 SmallVectorImpl<SlotIndex> *Kills,
229                 LiveIntervals &LIS, MachineDominatorTree &MDT,
230                 UserValueScopes &UVS);
231
232  /// addDefsFromCopies - The value in LI/LocNo may be copies to other
233  /// registers. Determine if any of the copies are available at the kill
234  /// points, and add defs if possible.
235  /// @param LI      Scan for copies of the value in LI->reg.
236  /// @param LocNo   Location number of LI->reg.
237  /// @param Kills   Points where the range of LocNo could be extended.
238  /// @param NewDefs Append (Idx, LocNo) of inserted defs here.
239  void addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
240                      const SmallVectorImpl<SlotIndex> &Kills,
241                      SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
242                      MachineRegisterInfo &MRI,
243                      LiveIntervals &LIS);
244
245  /// computeIntervals - Compute the live intervals of all locations after
246  /// collecting all their def points.
247  void computeIntervals(MachineRegisterInfo &MRI, const TargetRegisterInfo &TRI,
248                        LiveIntervals &LIS, MachineDominatorTree &MDT,
249                        UserValueScopes &UVS);
250
251  /// renameRegister - Update locations to rewrite OldReg as NewReg:SubIdx.
252  void renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx,
253                      const TargetRegisterInfo *TRI);
254
255  /// splitRegister - Replace OldReg ranges with NewRegs ranges where NewRegs is
256  /// live. Returns true if any changes were made.
257  bool splitRegister(unsigned OldLocNo, ArrayRef<LiveInterval*> NewRegs);
258
259  /// rewriteLocations - Rewrite virtual register locations according to the
260  /// provided virtual register map.
261  void rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI);
262
263  /// emitDebugVariables - Recreate DBG_VALUE instruction from data structures.
264  void emitDebugValues(VirtRegMap *VRM,
265                       LiveIntervals &LIS, const TargetInstrInfo &TRI);
266
267  /// findDebugLoc - Return DebugLoc used for this DBG_VALUE instruction. A
268  /// variable may have more than one corresponding DBG_VALUE instructions.
269  /// Only first one needs DebugLoc to identify variable's lexical scope
270  /// in source file.
271  DebugLoc findDebugLoc();
272
273  /// getDebugLoc - Return DebugLoc of this UserValue.
274  DebugLoc getDebugLoc() { return dl;}
275  void print(raw_ostream&, const TargetMachine*);
276};
277} // namespace
278
279/// LDVImpl - Implementation of the LiveDebugVariables pass.
280namespace {
281class LDVImpl {
282  LiveDebugVariables &pass;
283  LocMap::Allocator allocator;
284  MachineFunction *MF;
285  LiveIntervals *LIS;
286  LexicalScopes LS;
287  MachineDominatorTree *MDT;
288  const TargetRegisterInfo *TRI;
289
290  /// userValues - All allocated UserValue instances.
291  SmallVector<UserValue*, 8> userValues;
292
293  /// Map virtual register to eq class leader.
294  typedef DenseMap<unsigned, UserValue*> VRMap;
295  VRMap virtRegToEqClass;
296
297  /// Map user variable to eq class leader.
298  typedef DenseMap<const MDNode *, UserValue*> UVMap;
299  UVMap userVarMap;
300
301  /// getUserValue - Find or create a UserValue.
302  UserValue *getUserValue(const MDNode *Var, unsigned Offset, DebugLoc DL);
303
304  /// lookupVirtReg - Find the EC leader for VirtReg or null.
305  UserValue *lookupVirtReg(unsigned VirtReg);
306
307  /// handleDebugValue - Add DBG_VALUE instruction to our maps.
308  /// @param MI  DBG_VALUE instruction
309  /// @param Idx Last valid SLotIndex before instruction.
310  /// @return    True if the DBG_VALUE instruction should be deleted.
311  bool handleDebugValue(MachineInstr *MI, SlotIndex Idx);
312
313  /// collectDebugValues - Collect and erase all DBG_VALUE instructions, adding
314  /// a UserValue def for each instruction.
315  /// @param mf MachineFunction to be scanned.
316  /// @return True if any debug values were found.
317  bool collectDebugValues(MachineFunction &mf);
318
319  /// computeIntervals - Compute the live intervals of all user values after
320  /// collecting all their def points.
321  void computeIntervals();
322
323public:
324  LDVImpl(LiveDebugVariables *ps) : pass(*ps) {}
325  bool runOnMachineFunction(MachineFunction &mf);
326
327  /// clear - Relase all memory.
328  void clear() {
329    DeleteContainerPointers(userValues);
330    userValues.clear();
331    virtRegToEqClass.clear();
332    userVarMap.clear();
333  }
334
335  /// mapVirtReg - Map virtual register to an equivalence class.
336  void mapVirtReg(unsigned VirtReg, UserValue *EC);
337
338  /// renameRegister - Replace all references to OldReg with NewReg:SubIdx.
339  void renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx);
340
341  /// splitRegister -  Replace all references to OldReg with NewRegs.
342  void splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs);
343
344  /// emitDebugVariables - Recreate DBG_VALUE instruction from data structures.
345  void emitDebugValues(VirtRegMap *VRM);
346
347  void print(raw_ostream&);
348};
349} // namespace
350
351void UserValue::print(raw_ostream &OS, const TargetMachine *TM) {
352  DIVariable DV(variable);
353  OS << "!\"";
354  DV.printExtendedName(OS);
355  OS << "\"\t";
356  if (offset)
357    OS << '+' << offset;
358  for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) {
359    OS << " [" << I.start() << ';' << I.stop() << "):";
360    if (I.value() == ~0u)
361      OS << "undef";
362    else
363      OS << I.value();
364  }
365  for (unsigned i = 0, e = locations.size(); i != e; ++i) {
366    OS << " Loc" << i << '=';
367    locations[i].print(OS, TM);
368  }
369  OS << '\n';
370}
371
372void LDVImpl::print(raw_ostream &OS) {
373  OS << "********** DEBUG VARIABLES **********\n";
374  for (unsigned i = 0, e = userValues.size(); i != e; ++i)
375    userValues[i]->print(OS, &MF->getTarget());
376}
377
378void UserValue::coalesceLocation(unsigned LocNo) {
379  unsigned KeepLoc = 0;
380  for (unsigned e = locations.size(); KeepLoc != e; ++KeepLoc) {
381    if (KeepLoc == LocNo)
382      continue;
383    if (locations[KeepLoc].isIdenticalTo(locations[LocNo]))
384      break;
385  }
386  // No matches.
387  if (KeepLoc == locations.size())
388    return;
389
390  // Keep the smaller location, erase the larger one.
391  unsigned EraseLoc = LocNo;
392  if (KeepLoc > EraseLoc)
393    std::swap(KeepLoc, EraseLoc);
394  locations.erase(locations.begin() + EraseLoc);
395
396  // Rewrite values.
397  for (LocMap::iterator I = locInts.begin(); I.valid(); ++I) {
398    unsigned v = I.value();
399    if (v == EraseLoc)
400      I.setValue(KeepLoc);      // Coalesce when possible.
401    else if (v > EraseLoc)
402      I.setValueUnchecked(v-1); // Avoid coalescing with untransformed values.
403  }
404}
405
406void UserValue::mapVirtRegs(LDVImpl *LDV) {
407  for (unsigned i = 0, e = locations.size(); i != e; ++i)
408    if (locations[i].isReg() &&
409        TargetRegisterInfo::isVirtualRegister(locations[i].getReg()))
410      LDV->mapVirtReg(locations[i].getReg(), this);
411}
412
413UserValue *LDVImpl::getUserValue(const MDNode *Var, unsigned Offset,
414                                 DebugLoc DL) {
415  UserValue *&Leader = userVarMap[Var];
416  if (Leader) {
417    UserValue *UV = Leader->getLeader();
418    Leader = UV;
419    for (; UV; UV = UV->getNext())
420      if (UV->match(Var, Offset))
421        return UV;
422  }
423
424  UserValue *UV = new UserValue(Var, Offset, DL, allocator);
425  userValues.push_back(UV);
426  Leader = UserValue::merge(Leader, UV);
427  return UV;
428}
429
430void LDVImpl::mapVirtReg(unsigned VirtReg, UserValue *EC) {
431  assert(TargetRegisterInfo::isVirtualRegister(VirtReg) && "Only map VirtRegs");
432  UserValue *&Leader = virtRegToEqClass[VirtReg];
433  Leader = UserValue::merge(Leader, EC);
434}
435
436UserValue *LDVImpl::lookupVirtReg(unsigned VirtReg) {
437  if (UserValue *UV = virtRegToEqClass.lookup(VirtReg))
438    return UV->getLeader();
439  return 0;
440}
441
442bool LDVImpl::handleDebugValue(MachineInstr *MI, SlotIndex Idx) {
443  // DBG_VALUE loc, offset, variable
444  if (MI->getNumOperands() != 3 ||
445      !MI->getOperand(1).isImm() || !MI->getOperand(2).isMetadata()) {
446    DEBUG(dbgs() << "Can't handle " << *MI);
447    return false;
448  }
449
450  // Get or create the UserValue for (variable,offset).
451  unsigned Offset = MI->getOperand(1).getImm();
452  const MDNode *Var = MI->getOperand(2).getMetadata();
453  UserValue *UV = getUserValue(Var, Offset, MI->getDebugLoc());
454  UV->addDef(Idx, MI->getOperand(0));
455  return true;
456}
457
458bool LDVImpl::collectDebugValues(MachineFunction &mf) {
459  bool Changed = false;
460  for (MachineFunction::iterator MFI = mf.begin(), MFE = mf.end(); MFI != MFE;
461       ++MFI) {
462    MachineBasicBlock *MBB = MFI;
463    for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
464         MBBI != MBBE;) {
465      if (!MBBI->isDebugValue()) {
466        ++MBBI;
467        continue;
468      }
469      // DBG_VALUE has no slot index, use the previous instruction instead.
470      SlotIndex Idx = MBBI == MBB->begin() ?
471        LIS->getMBBStartIdx(MBB) :
472        LIS->getInstructionIndex(llvm::prior(MBBI)).getRegSlot();
473      // Handle consecutive DBG_VALUE instructions with the same slot index.
474      do {
475        if (handleDebugValue(MBBI, Idx)) {
476          MBBI = MBB->erase(MBBI);
477          Changed = true;
478        } else
479          ++MBBI;
480      } while (MBBI != MBBE && MBBI->isDebugValue());
481    }
482  }
483  return Changed;
484}
485
486void UserValue::extendDef(SlotIndex Idx, unsigned LocNo,
487                          LiveInterval *LI, const VNInfo *VNI,
488                          SmallVectorImpl<SlotIndex> *Kills,
489                          LiveIntervals &LIS, MachineDominatorTree &MDT,
490                          UserValueScopes &UVS) {
491  SmallVector<SlotIndex, 16> Todo;
492  Todo.push_back(Idx);
493  do {
494    SlotIndex Start = Todo.pop_back_val();
495    MachineBasicBlock *MBB = LIS.getMBBFromIndex(Start);
496    SlotIndex Stop = LIS.getMBBEndIdx(MBB);
497    LocMap::iterator I = locInts.find(Start);
498
499    // Limit to VNI's live range.
500    bool ToEnd = true;
501    if (LI && VNI) {
502      LiveRange *Range = LI->getLiveRangeContaining(Start);
503      if (!Range || Range->valno != VNI) {
504        if (Kills)
505          Kills->push_back(Start);
506        continue;
507      }
508      if (Range->end < Stop)
509        Stop = Range->end, ToEnd = false;
510    }
511
512    // There could already be a short def at Start.
513    if (I.valid() && I.start() <= Start) {
514      // Stop when meeting a different location or an already extended interval.
515      Start = Start.getNextSlot();
516      if (I.value() != LocNo || I.stop() != Start)
517        continue;
518      // This is a one-slot placeholder. Just skip it.
519      ++I;
520    }
521
522    // Limited by the next def.
523    if (I.valid() && I.start() < Stop)
524      Stop = I.start(), ToEnd = false;
525    // Limited by VNI's live range.
526    else if (!ToEnd && Kills)
527      Kills->push_back(Stop);
528
529    if (Start >= Stop)
530      continue;
531
532    I.insert(Start, Stop, LocNo);
533
534    // If we extended to the MBB end, propagate down the dominator tree.
535    if (!ToEnd)
536      continue;
537    const std::vector<MachineDomTreeNode*> &Children =
538      MDT.getNode(MBB)->getChildren();
539    for (unsigned i = 0, e = Children.size(); i != e; ++i) {
540      MachineBasicBlock *MBB = Children[i]->getBlock();
541      if (UVS.dominates(MBB))
542        Todo.push_back(LIS.getMBBStartIdx(MBB));
543    }
544  } while (!Todo.empty());
545}
546
547void
548UserValue::addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
549                      const SmallVectorImpl<SlotIndex> &Kills,
550                      SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
551                      MachineRegisterInfo &MRI, LiveIntervals &LIS) {
552  if (Kills.empty())
553    return;
554  // Don't track copies from physregs, there are too many uses.
555  if (!TargetRegisterInfo::isVirtualRegister(LI->reg))
556    return;
557
558  // Collect all the (vreg, valno) pairs that are copies of LI.
559  SmallVector<std::pair<LiveInterval*, const VNInfo*>, 8> CopyValues;
560  for (MachineRegisterInfo::use_nodbg_iterator
561         UI = MRI.use_nodbg_begin(LI->reg),
562         UE = MRI.use_nodbg_end(); UI != UE; ++UI) {
563    // Copies of the full value.
564    if (UI.getOperand().getSubReg() || !UI->isCopy())
565      continue;
566    MachineInstr *MI = &*UI;
567    unsigned DstReg = MI->getOperand(0).getReg();
568
569    // Don't follow copies to physregs. These are usually setting up call
570    // arguments, and the argument registers are always call clobbered. We are
571    // better off in the source register which could be a callee-saved register,
572    // or it could be spilled.
573    if (!TargetRegisterInfo::isVirtualRegister(DstReg))
574      continue;
575
576    // Is LocNo extended to reach this copy? If not, another def may be blocking
577    // it, or we are looking at a wrong value of LI.
578    SlotIndex Idx = LIS.getInstructionIndex(MI);
579    LocMap::iterator I = locInts.find(Idx.getRegSlot(true));
580    if (!I.valid() || I.value() != LocNo)
581      continue;
582
583    if (!LIS.hasInterval(DstReg))
584      continue;
585    LiveInterval *DstLI = &LIS.getInterval(DstReg);
586    const VNInfo *DstVNI = DstLI->getVNInfoAt(Idx.getRegSlot());
587    assert(DstVNI && DstVNI->def == Idx.getRegSlot() && "Bad copy value");
588    CopyValues.push_back(std::make_pair(DstLI, DstVNI));
589  }
590
591  if (CopyValues.empty())
592    return;
593
594  DEBUG(dbgs() << "Got " << CopyValues.size() << " copies of " << *LI << '\n');
595
596  // Try to add defs of the copied values for each kill point.
597  for (unsigned i = 0, e = Kills.size(); i != e; ++i) {
598    SlotIndex Idx = Kills[i];
599    for (unsigned j = 0, e = CopyValues.size(); j != e; ++j) {
600      LiveInterval *DstLI = CopyValues[j].first;
601      const VNInfo *DstVNI = CopyValues[j].second;
602      if (DstLI->getVNInfoAt(Idx) != DstVNI)
603        continue;
604      // Check that there isn't already a def at Idx
605      LocMap::iterator I = locInts.find(Idx);
606      if (I.valid() && I.start() <= Idx)
607        continue;
608      DEBUG(dbgs() << "Kill at " << Idx << " covered by valno #"
609                   << DstVNI->id << " in " << *DstLI << '\n');
610      MachineInstr *CopyMI = LIS.getInstructionFromIndex(DstVNI->def);
611      assert(CopyMI && CopyMI->isCopy() && "Bad copy value");
612      unsigned LocNo = getLocationNo(CopyMI->getOperand(0));
613      I.insert(Idx, Idx.getNextSlot(), LocNo);
614      NewDefs.push_back(std::make_pair(Idx, LocNo));
615      break;
616    }
617  }
618}
619
620void
621UserValue::computeIntervals(MachineRegisterInfo &MRI,
622                            const TargetRegisterInfo &TRI,
623                            LiveIntervals &LIS,
624                            MachineDominatorTree &MDT,
625                            UserValueScopes &UVS) {
626  SmallVector<std::pair<SlotIndex, unsigned>, 16> Defs;
627
628  // Collect all defs to be extended (Skipping undefs).
629  for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I)
630    if (I.value() != ~0u)
631      Defs.push_back(std::make_pair(I.start(), I.value()));
632
633  // Extend all defs, and possibly add new ones along the way.
634  for (unsigned i = 0; i != Defs.size(); ++i) {
635    SlotIndex Idx = Defs[i].first;
636    unsigned LocNo = Defs[i].second;
637    const MachineOperand &Loc = locations[LocNo];
638
639    if (!Loc.isReg()) {
640      extendDef(Idx, LocNo, 0, 0, 0, LIS, MDT, UVS);
641      continue;
642    }
643
644    // Register locations are constrained to where the register value is live.
645    if (TargetRegisterInfo::isVirtualRegister(Loc.getReg())) {
646      LiveInterval *LI = 0;
647      const VNInfo *VNI = 0;
648      if (LIS.hasInterval(Loc.getReg())) {
649        LI = &LIS.getInterval(Loc.getReg());
650        VNI = LI->getVNInfoAt(Idx);
651      }
652      SmallVector<SlotIndex, 16> Kills;
653      extendDef(Idx, LocNo, LI, VNI, &Kills, LIS, MDT, UVS);
654      if (LI)
655        addDefsFromCopies(LI, LocNo, Kills, Defs, MRI, LIS);
656      continue;
657    }
658
659    // For physregs, use the live range of the first regunit as a guide.
660    unsigned Unit = *MCRegUnitIterator(Loc.getReg(), &TRI);
661    LiveInterval *LI = &LIS.getRegUnit(Unit);
662    const VNInfo *VNI = LI->getVNInfoAt(Idx);
663    // Don't track copies from physregs, it is too expensive.
664    extendDef(Idx, LocNo, LI, VNI, 0, LIS, MDT, UVS);
665  }
666
667  // Finally, erase all the undefs.
668  for (LocMap::iterator I = locInts.begin(); I.valid();)
669    if (I.value() == ~0u)
670      I.erase();
671    else
672      ++I;
673}
674
675void LDVImpl::computeIntervals() {
676  for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
677    UserValueScopes UVS(userValues[i]->getDebugLoc(), LS);
678    userValues[i]->computeIntervals(MF->getRegInfo(), *TRI, *LIS, *MDT, UVS);
679    userValues[i]->mapVirtRegs(this);
680  }
681}
682
683bool LDVImpl::runOnMachineFunction(MachineFunction &mf) {
684  MF = &mf;
685  LIS = &pass.getAnalysis<LiveIntervals>();
686  MDT = &pass.getAnalysis<MachineDominatorTree>();
687  TRI = mf.getTarget().getRegisterInfo();
688  clear();
689  LS.initialize(mf);
690  DEBUG(dbgs() << "********** COMPUTING LIVE DEBUG VARIABLES: "
691               << mf.getName() << " **********\n");
692
693  bool Changed = collectDebugValues(mf);
694  computeIntervals();
695  DEBUG(print(dbgs()));
696  LS.releaseMemory();
697  return Changed;
698}
699
700bool LiveDebugVariables::runOnMachineFunction(MachineFunction &mf) {
701  if (!EnableLDV)
702    return false;
703  if (!pImpl)
704    pImpl = new LDVImpl(this);
705  ModifiedMF = static_cast<LDVImpl*>(pImpl)->runOnMachineFunction(mf);
706  return ModifiedMF;
707}
708
709void LiveDebugVariables::releaseMemory() {
710  if (pImpl) {
711    static_cast<LDVImpl*>(pImpl)->clear();
712    // Make sure we call emitDebugValues if the machine function was modified.
713    assert((!ModifiedMF || EmitDone) &&
714           "Dbg values are not emitted in LDV");
715  }
716}
717
718LiveDebugVariables::~LiveDebugVariables() {
719  if (pImpl)
720    delete static_cast<LDVImpl*>(pImpl);
721}
722
723void UserValue::
724renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx,
725               const TargetRegisterInfo *TRI) {
726  for (unsigned i = locations.size(); i; --i) {
727    unsigned LocNo = i - 1;
728    MachineOperand &Loc = locations[LocNo];
729    if (!Loc.isReg() || Loc.getReg() != OldReg)
730      continue;
731    if (TargetRegisterInfo::isPhysicalRegister(NewReg))
732      Loc.substPhysReg(NewReg, *TRI);
733    else
734      Loc.substVirtReg(NewReg, SubIdx, *TRI);
735    coalesceLocation(LocNo);
736  }
737}
738
739void LDVImpl::
740renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx) {
741  UserValue *UV = lookupVirtReg(OldReg);
742  if (!UV)
743    return;
744
745  if (TargetRegisterInfo::isVirtualRegister(NewReg))
746    mapVirtReg(NewReg, UV);
747  if (OldReg != NewReg)
748    virtRegToEqClass.erase(OldReg);
749
750  do {
751    UV->renameRegister(OldReg, NewReg, SubIdx, TRI);
752    UV = UV->getNext();
753  } while (UV);
754}
755
756void LiveDebugVariables::
757renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx) {
758  if (pImpl)
759    static_cast<LDVImpl*>(pImpl)->renameRegister(OldReg, NewReg, SubIdx);
760}
761
762//===----------------------------------------------------------------------===//
763//                           Live Range Splitting
764//===----------------------------------------------------------------------===//
765
766bool
767UserValue::splitLocation(unsigned OldLocNo, ArrayRef<LiveInterval*> NewRegs) {
768  DEBUG({
769    dbgs() << "Splitting Loc" << OldLocNo << '\t';
770    print(dbgs(), 0);
771  });
772  bool DidChange = false;
773  LocMap::iterator LocMapI;
774  LocMapI.setMap(locInts);
775  for (unsigned i = 0; i != NewRegs.size(); ++i) {
776    LiveInterval *LI = NewRegs[i];
777    if (LI->empty())
778      continue;
779
780    // Don't allocate the new LocNo until it is needed.
781    unsigned NewLocNo = ~0u;
782
783    // Iterate over the overlaps between locInts and LI.
784    LocMapI.find(LI->beginIndex());
785    if (!LocMapI.valid())
786      continue;
787    LiveInterval::iterator LII = LI->advanceTo(LI->begin(), LocMapI.start());
788    LiveInterval::iterator LIE = LI->end();
789    while (LocMapI.valid() && LII != LIE) {
790      // At this point, we know that LocMapI.stop() > LII->start.
791      LII = LI->advanceTo(LII, LocMapI.start());
792      if (LII == LIE)
793        break;
794
795      // Now LII->end > LocMapI.start(). Do we have an overlap?
796      if (LocMapI.value() == OldLocNo && LII->start < LocMapI.stop()) {
797        // Overlapping correct location. Allocate NewLocNo now.
798        if (NewLocNo == ~0u) {
799          MachineOperand MO = MachineOperand::CreateReg(LI->reg, false);
800          MO.setSubReg(locations[OldLocNo].getSubReg());
801          NewLocNo = getLocationNo(MO);
802          DidChange = true;
803        }
804
805        SlotIndex LStart = LocMapI.start();
806        SlotIndex LStop  = LocMapI.stop();
807
808        // Trim LocMapI down to the LII overlap.
809        if (LStart < LII->start)
810          LocMapI.setStartUnchecked(LII->start);
811        if (LStop > LII->end)
812          LocMapI.setStopUnchecked(LII->end);
813
814        // Change the value in the overlap. This may trigger coalescing.
815        LocMapI.setValue(NewLocNo);
816
817        // Re-insert any removed OldLocNo ranges.
818        if (LStart < LocMapI.start()) {
819          LocMapI.insert(LStart, LocMapI.start(), OldLocNo);
820          ++LocMapI;
821          assert(LocMapI.valid() && "Unexpected coalescing");
822        }
823        if (LStop > LocMapI.stop()) {
824          ++LocMapI;
825          LocMapI.insert(LII->end, LStop, OldLocNo);
826          --LocMapI;
827        }
828      }
829
830      // Advance to the next overlap.
831      if (LII->end < LocMapI.stop()) {
832        if (++LII == LIE)
833          break;
834        LocMapI.advanceTo(LII->start);
835      } else {
836        ++LocMapI;
837        if (!LocMapI.valid())
838          break;
839        LII = LI->advanceTo(LII, LocMapI.start());
840      }
841    }
842  }
843
844  // Finally, remove any remaining OldLocNo intervals and OldLocNo itself.
845  locations.erase(locations.begin() + OldLocNo);
846  LocMapI.goToBegin();
847  while (LocMapI.valid()) {
848    unsigned v = LocMapI.value();
849    if (v == OldLocNo) {
850      DEBUG(dbgs() << "Erasing [" << LocMapI.start() << ';'
851                   << LocMapI.stop() << ")\n");
852      LocMapI.erase();
853    } else {
854      if (v > OldLocNo)
855        LocMapI.setValueUnchecked(v-1);
856      ++LocMapI;
857    }
858  }
859
860  DEBUG({dbgs() << "Split result: \t"; print(dbgs(), 0);});
861  return DidChange;
862}
863
864bool
865UserValue::splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs) {
866  bool DidChange = false;
867  // Split locations referring to OldReg. Iterate backwards so splitLocation can
868  // safely erase unused locations.
869  for (unsigned i = locations.size(); i ; --i) {
870    unsigned LocNo = i-1;
871    const MachineOperand *Loc = &locations[LocNo];
872    if (!Loc->isReg() || Loc->getReg() != OldReg)
873      continue;
874    DidChange |= splitLocation(LocNo, NewRegs);
875  }
876  return DidChange;
877}
878
879void LDVImpl::splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs) {
880  bool DidChange = false;
881  for (UserValue *UV = lookupVirtReg(OldReg); UV; UV = UV->getNext())
882    DidChange |= UV->splitRegister(OldReg, NewRegs);
883
884  if (!DidChange)
885    return;
886
887  // Map all of the new virtual registers.
888  UserValue *UV = lookupVirtReg(OldReg);
889  for (unsigned i = 0; i != NewRegs.size(); ++i)
890    mapVirtReg(NewRegs[i]->reg, UV);
891}
892
893void LiveDebugVariables::
894splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs) {
895  if (pImpl)
896    static_cast<LDVImpl*>(pImpl)->splitRegister(OldReg, NewRegs);
897}
898
899void
900UserValue::rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI) {
901  // Iterate over locations in reverse makes it easier to handle coalescing.
902  for (unsigned i = locations.size(); i ; --i) {
903    unsigned LocNo = i-1;
904    MachineOperand &Loc = locations[LocNo];
905    // Only virtual registers are rewritten.
906    if (!Loc.isReg() || !Loc.getReg() ||
907        !TargetRegisterInfo::isVirtualRegister(Loc.getReg()))
908      continue;
909    unsigned VirtReg = Loc.getReg();
910    if (VRM.isAssignedReg(VirtReg) &&
911        TargetRegisterInfo::isPhysicalRegister(VRM.getPhys(VirtReg))) {
912      // This can create a %noreg operand in rare cases when the sub-register
913      // index is no longer available. That means the user value is in a
914      // non-existent sub-register, and %noreg is exactly what we want.
915      Loc.substPhysReg(VRM.getPhys(VirtReg), TRI);
916    } else if (VRM.getStackSlot(VirtReg) != VirtRegMap::NO_STACK_SLOT) {
917      // FIXME: Translate SubIdx to a stackslot offset.
918      Loc = MachineOperand::CreateFI(VRM.getStackSlot(VirtReg));
919    } else {
920      Loc.setReg(0);
921      Loc.setSubReg(0);
922    }
923    coalesceLocation(LocNo);
924  }
925}
926
927/// findInsertLocation - Find an iterator for inserting a DBG_VALUE
928/// instruction.
929static MachineBasicBlock::iterator
930findInsertLocation(MachineBasicBlock *MBB, SlotIndex Idx,
931                   LiveIntervals &LIS) {
932  SlotIndex Start = LIS.getMBBStartIdx(MBB);
933  Idx = Idx.getBaseIndex();
934
935  // Try to find an insert location by going backwards from Idx.
936  MachineInstr *MI;
937  while (!(MI = LIS.getInstructionFromIndex(Idx))) {
938    // We've reached the beginning of MBB.
939    if (Idx == Start) {
940      MachineBasicBlock::iterator I = MBB->SkipPHIsAndLabels(MBB->begin());
941      return I;
942    }
943    Idx = Idx.getPrevIndex();
944  }
945
946  // Don't insert anything after the first terminator, though.
947  return MI->isTerminator() ? MBB->getFirstTerminator() :
948                              llvm::next(MachineBasicBlock::iterator(MI));
949}
950
951DebugLoc UserValue::findDebugLoc() {
952  DebugLoc D = dl;
953  dl = DebugLoc();
954  return D;
955}
956void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx,
957                                 unsigned LocNo,
958                                 LiveIntervals &LIS,
959                                 const TargetInstrInfo &TII) {
960  MachineBasicBlock::iterator I = findInsertLocation(MBB, Idx, LIS);
961  MachineOperand &Loc = locations[LocNo];
962  ++NumInsertedDebugValues;
963
964  // Frame index locations may require a target callback.
965  if (Loc.isFI()) {
966    MachineInstr *MI = TII.emitFrameIndexDebugValue(*MBB->getParent(),
967                                          Loc.getIndex(), offset, variable,
968                                                    findDebugLoc());
969    if (MI) {
970      MBB->insert(I, MI);
971      return;
972    }
973  }
974  // This is not a frame index, or the target is happy with a standard FI.
975  BuildMI(*MBB, I, findDebugLoc(), TII.get(TargetOpcode::DBG_VALUE))
976    .addOperand(Loc).addImm(offset).addMetadata(variable);
977}
978
979void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
980                                const TargetInstrInfo &TII) {
981  MachineFunction::iterator MFEnd = VRM->getMachineFunction().end();
982
983  for (LocMap::const_iterator I = locInts.begin(); I.valid();) {
984    SlotIndex Start = I.start();
985    SlotIndex Stop = I.stop();
986    unsigned LocNo = I.value();
987    DEBUG(dbgs() << "\t[" << Start << ';' << Stop << "):" << LocNo);
988    MachineFunction::iterator MBB = LIS.getMBBFromIndex(Start);
989    SlotIndex MBBEnd = LIS.getMBBEndIdx(MBB);
990
991    DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
992    insertDebugValue(MBB, Start, LocNo, LIS, TII);
993    // This interval may span multiple basic blocks.
994    // Insert a DBG_VALUE into each one.
995    while(Stop > MBBEnd) {
996      // Move to the next block.
997      Start = MBBEnd;
998      if (++MBB == MFEnd)
999        break;
1000      MBBEnd = LIS.getMBBEndIdx(MBB);
1001      DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
1002      insertDebugValue(MBB, Start, LocNo, LIS, TII);
1003    }
1004    DEBUG(dbgs() << '\n');
1005    if (MBB == MFEnd)
1006      break;
1007
1008    ++I;
1009  }
1010}
1011
1012void LDVImpl::emitDebugValues(VirtRegMap *VRM) {
1013  DEBUG(dbgs() << "********** EMITTING LIVE DEBUG VARIABLES **********\n");
1014  const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
1015  for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
1016    DEBUG(userValues[i]->print(dbgs(), &MF->getTarget()));
1017    userValues[i]->rewriteLocations(*VRM, *TRI);
1018    userValues[i]->emitDebugValues(VRM, *LIS, *TII);
1019  }
1020}
1021
1022void LiveDebugVariables::emitDebugValues(VirtRegMap *VRM) {
1023  if (pImpl) {
1024    static_cast<LDVImpl*>(pImpl)->emitDebugValues(VRM);
1025    EmitDone = true;
1026  }
1027}
1028
1029
1030#ifndef NDEBUG
1031void LiveDebugVariables::dump() {
1032  if (pImpl)
1033    static_cast<LDVImpl*>(pImpl)->print(dbgs());
1034}
1035#endif
1036
1037