LiveDebugVariables.cpp revision ad90d3a343ca73c32693e2b05b74462ccd9659cd 
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/ADT/Statistic.h"
30#include "llvm/CodeGen/LiveIntervalAnalysis.h"
31#include "llvm/CodeGen/MachineDominators.h"
32#include "llvm/CodeGen/MachineFunction.h"
33#include "llvm/CodeGen/MachineInstrBuilder.h"
34#include "llvm/CodeGen/MachineRegisterInfo.h"
35#include "llvm/CodeGen/Passes.h"
36#include "llvm/Support/CommandLine.h"
37#include "llvm/Support/Debug.h"
38#include "llvm/Target/TargetInstrInfo.h"
39#include "llvm/Target/TargetMachine.h"
40#include "llvm/Target/TargetRegisterInfo.h"
41
42using namespace llvm;
43
44static cl::opt<bool>
45EnableLDV("live-debug-variables", cl::init(true),
46          cl::desc("Enable the live debug variables pass"), cl::Hidden);
47
48STATISTIC(NumInsertedDebugValues, "Number of DBG_VALUEs inserted");
49char LiveDebugVariables::ID = 0;
50
51INITIALIZE_PASS_BEGIN(LiveDebugVariables, "livedebugvars",
52                "Debug Variable Analysis", false, false)
53INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
54INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
55INITIALIZE_PASS_END(LiveDebugVariables, "livedebugvars",
56                "Debug Variable Analysis", false, false)
57
58void LiveDebugVariables::getAnalysisUsage(AnalysisUsage &AU) const {
59  AU.addRequired<MachineDominatorTree>();
60  AU.addRequiredTransitive<LiveIntervals>();
61  AU.setPreservesAll();
62  MachineFunctionPass::getAnalysisUsage(AU);
63}
64
65LiveDebugVariables::LiveDebugVariables() : MachineFunctionPass(ID), pImpl(0) {
66  initializeLiveDebugVariablesPass(*PassRegistry::getPassRegistry());
67}
68
69/// LocMap - Map of where a user value is live, and its location.
70typedef IntervalMap<SlotIndex, unsigned, 4> LocMap;
71
72/// UserValue - A user value is a part of a debug info user variable.
73///
74/// A DBG_VALUE instruction notes that (a sub-register of) a virtual register
75/// holds part of a user variable. The part is identified by a byte offset.
76///
77/// UserValues are grouped into equivalence classes for easier searching. Two
78/// user values are related if they refer to the same variable, or if they are
79/// held by the same virtual register. The equivalence class is the transitive
80/// closure of that relation.
81namespace {
82class LDVImpl;
83class UserValue {
84  const MDNode *variable; ///< The debug info variable we are part of.
85  unsigned offset;        ///< Byte offset into variable.
86  DebugLoc dl;            ///< The debug location for the variable. This is
87                          ///< used by dwarf writer to find lexical scope.
88  UserValue *leader;      ///< Equivalence class leader.
89  UserValue *next;        ///< Next value in equivalence class, or null.
90
91  /// Numbered locations referenced by locmap.
92  SmallVector<MachineOperand, 4> locations;
93
94  /// Map of slot indices where this value is live.
95  LocMap locInts;
96
97  /// coalesceLocation - After LocNo was changed, check if it has become
98  /// identical to another location, and coalesce them. This may cause LocNo or
99  /// a later location to be erased, but no earlier location will be erased.
100  void coalesceLocation(unsigned LocNo);
101
102  /// insertDebugValue - Insert a DBG_VALUE into MBB at Idx for LocNo.
103  void insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx, unsigned LocNo,
104                        LiveIntervals &LIS, const TargetInstrInfo &TII);
105
106  /// splitLocation - Replace OldLocNo ranges with NewRegs ranges where NewRegs
107  /// is live. Returns true if any changes were made.
108  bool splitLocation(unsigned OldLocNo, ArrayRef<LiveInterval*> NewRegs);
109
110public:
111  /// UserValue - Create a new UserValue.
112  UserValue(const MDNode *var, unsigned o, DebugLoc L,
113            LocMap::Allocator &alloc)
114    : variable(var), offset(o), dl(L), leader(this), next(0), locInts(alloc)
115  {}
116
117  /// getLeader - Get the leader of this value's equivalence class.
118  UserValue *getLeader() {
119    UserValue *l = leader;
120    while (l != l->leader)
121      l = l->leader;
122    return leader = l;
123  }
124
125  /// getNext - Return the next UserValue in the equivalence class.
126  UserValue *getNext() const { return next; }
127
128  /// match - Does this UserValue match the parameters?
129  bool match(const MDNode *Var, unsigned Offset) const {
130    return Var == variable && Offset == offset;
131  }
132
133  /// merge - Merge equivalence classes.
134  static UserValue *merge(UserValue *L1, UserValue *L2) {
135    L2 = L2->getLeader();
136    if (!L1)
137      return L2;
138    L1 = L1->getLeader();
139    if (L1 == L2)
140      return L1;
141    // Splice L2 before L1's members.
142    UserValue *End = L2;
143    while (End->next)
144      End->leader = L1, End = End->next;
145    End->leader = L1;
146    End->next = L1->next;
147    L1->next = L2;
148    return L1;
149  }
150
151  /// getLocationNo - Return the location number that matches Loc.
152  unsigned getLocationNo(const MachineOperand &LocMO) {
153    if (LocMO.isReg()) {
154      if (LocMO.getReg() == 0)
155        return ~0u;
156      // For register locations we dont care about use/def and other flags.
157      for (unsigned i = 0, e = locations.size(); i != e; ++i)
158        if (locations[i].isReg() &&
159            locations[i].getReg() == LocMO.getReg() &&
160            locations[i].getSubReg() == LocMO.getSubReg())
161          return i;
162    } else
163      for (unsigned i = 0, e = locations.size(); i != e; ++i)
164        if (LocMO.isIdenticalTo(locations[i]))
165          return i;
166    locations.push_back(LocMO);
167    // We are storing a MachineOperand outside a MachineInstr.
168    locations.back().clearParent();
169    // Don't store def operands.
170    if (locations.back().isReg())
171      locations.back().setIsUse();
172    return locations.size() - 1;
173  }
174
175  /// mapVirtRegs - Ensure that all virtual register locations are mapped.
176  void mapVirtRegs(LDVImpl *LDV);
177
178  /// addDef - Add a definition point to this value.
179  void addDef(SlotIndex Idx, const MachineOperand &LocMO) {
180    // Add a singular (Idx,Idx) -> Loc mapping.
181    LocMap::iterator I = locInts.find(Idx);
182    if (!I.valid() || I.start() != Idx)
183      I.insert(Idx, Idx.getNextSlot(), getLocationNo(LocMO));
184    else
185      // A later DBG_VALUE at the same SlotIndex overrides the old location.
186      I.setValue(getLocationNo(LocMO));
187  }
188
189  /// extendDef - Extend the current definition as far as possible down the
190  /// dominator tree. Stop when meeting an existing def or when leaving the live
191  /// range of VNI.
192  /// End points where VNI is no longer live are added to Kills.
193  /// @param Idx   Starting point for the definition.
194  /// @param LocNo Location number to propagate.
195  /// @param LI    Restrict liveness to where LI has the value VNI. May be null.
196  /// @param VNI   When LI is not null, this is the value to restrict to.
197  /// @param Kills Append end points of VNI's live range to Kills.
198  /// @param LIS   Live intervals analysis.
199  /// @param MDT   Dominator tree.
200  void extendDef(SlotIndex Idx, unsigned LocNo,
201                 LiveInterval *LI, const VNInfo *VNI,
202                 SmallVectorImpl<SlotIndex> *Kills,
203                 LiveIntervals &LIS, MachineDominatorTree &MDT);
204
205  /// addDefsFromCopies - The value in LI/LocNo may be copies to other
206  /// registers. Determine if any of the copies are available at the kill
207  /// points, and add defs if possible.
208  /// @param LI      Scan for copies of the value in LI->reg.
209  /// @param LocNo   Location number of LI->reg.
210  /// @param Kills   Points where the range of LocNo could be extended.
211  /// @param NewDefs Append (Idx, LocNo) of inserted defs here.
212  void addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
213                      const SmallVectorImpl<SlotIndex> &Kills,
214                      SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
215                      MachineRegisterInfo &MRI,
216                      LiveIntervals &LIS);
217
218  /// computeIntervals - Compute the live intervals of all locations after
219  /// collecting all their def points.
220  void computeIntervals(MachineRegisterInfo &MRI,
221                        LiveIntervals &LIS, MachineDominatorTree &MDT);
222
223  /// renameRegister - Update locations to rewrite OldReg as NewReg:SubIdx.
224  void renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx,
225                      const TargetRegisterInfo *TRI);
226
227  /// splitRegister - Replace OldReg ranges with NewRegs ranges where NewRegs is
228  /// live. Returns true if any changes were made.
229  bool splitRegister(unsigned OldLocNo, ArrayRef<LiveInterval*> NewRegs);
230
231  /// rewriteLocations - Rewrite virtual register locations according to the
232  /// provided virtual register map.
233  void rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI);
234
235  /// emitDebugVariables - Recreate DBG_VALUE instruction from data structures.
236  void emitDebugValues(VirtRegMap *VRM,
237                       LiveIntervals &LIS, const TargetInstrInfo &TRI);
238
239  /// findDebugLoc - Return DebugLoc used for this DBG_VALUE instruction. A
240  /// variable may have more than one corresponding DBG_VALUE instructions.
241  /// Only first one needs DebugLoc to identify variable's lexical scope
242  /// in source file.
243  DebugLoc findDebugLoc();
244  void print(raw_ostream&, const TargetMachine*);
245};
246} // namespace
247
248/// LDVImpl - Implementation of the LiveDebugVariables pass.
249namespace {
250class LDVImpl {
251  LiveDebugVariables &pass;
252  LocMap::Allocator allocator;
253  MachineFunction *MF;
254  LiveIntervals *LIS;
255  MachineDominatorTree *MDT;
256  const TargetRegisterInfo *TRI;
257
258  /// userValues - All allocated UserValue instances.
259  SmallVector<UserValue*, 8> userValues;
260
261  /// Map virtual register to eq class leader.
262  typedef DenseMap<unsigned, UserValue*> VRMap;
263  VRMap virtRegToEqClass;
264
265  /// Map user variable to eq class leader.
266  typedef DenseMap<const MDNode *, UserValue*> UVMap;
267  UVMap userVarMap;
268
269  /// getUserValue - Find or create a UserValue.
270  UserValue *getUserValue(const MDNode *Var, unsigned Offset, DebugLoc DL);
271
272  /// lookupVirtReg - Find the EC leader for VirtReg or null.
273  UserValue *lookupVirtReg(unsigned VirtReg);
274
275  /// handleDebugValue - Add DBG_VALUE instruction to our maps.
276  /// @param MI  DBG_VALUE instruction
277  /// @param Idx Last valid SLotIndex before instruction.
278  /// @return    True if the DBG_VALUE instruction should be deleted.
279  bool handleDebugValue(MachineInstr *MI, SlotIndex Idx);
280
281  /// collectDebugValues - Collect and erase all DBG_VALUE instructions, adding
282  /// a UserValue def for each instruction.
283  /// @param mf MachineFunction to be scanned.
284  /// @return True if any debug values were found.
285  bool collectDebugValues(MachineFunction &mf);
286
287  /// computeIntervals - Compute the live intervals of all user values after
288  /// collecting all their def points.
289  void computeIntervals();
290
291public:
292  LDVImpl(LiveDebugVariables *ps) : pass(*ps) {}
293  bool runOnMachineFunction(MachineFunction &mf);
294
295  /// clear - Relase all memory.
296  void clear() {
297    DeleteContainerPointers(userValues);
298    userValues.clear();
299    virtRegToEqClass.clear();
300    userVarMap.clear();
301  }
302
303  /// mapVirtReg - Map virtual register to an equivalence class.
304  void mapVirtReg(unsigned VirtReg, UserValue *EC);
305
306  /// renameRegister - Replace all references to OldReg with NewReg:SubIdx.
307  void renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx);
308
309  /// splitRegister -  Replace all references to OldReg with NewRegs.
310  void splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs);
311
312  /// emitDebugVariables - Recreate DBG_VALUE instruction from data structures.
313  void emitDebugValues(VirtRegMap *VRM);
314
315  void print(raw_ostream&);
316};
317} // namespace
318
319void UserValue::print(raw_ostream &OS, const TargetMachine *TM) {
320  if (const MDString *MDS = dyn_cast<MDString>(variable->getOperand(2)))
321    OS << "!\"" << MDS->getString() << "\"\t";
322  if (offset)
323    OS << '+' << offset;
324  for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) {
325    OS << " [" << I.start() << ';' << I.stop() << "):";
326    if (I.value() == ~0u)
327      OS << "undef";
328    else
329      OS << I.value();
330  }
331  for (unsigned i = 0, e = locations.size(); i != e; ++i) {
332    OS << " Loc" << i << '=';
333    locations[i].print(OS, TM);
334  }
335  OS << '\n';
336}
337
338void LDVImpl::print(raw_ostream &OS) {
339  OS << "********** DEBUG VARIABLES **********\n";
340  for (unsigned i = 0, e = userValues.size(); i != e; ++i)
341    userValues[i]->print(OS, &MF->getTarget());
342}
343
344void UserValue::coalesceLocation(unsigned LocNo) {
345  unsigned KeepLoc = 0;
346  for (unsigned e = locations.size(); KeepLoc != e; ++KeepLoc) {
347    if (KeepLoc == LocNo)
348      continue;
349    if (locations[KeepLoc].isIdenticalTo(locations[LocNo]))
350      break;
351  }
352  // No matches.
353  if (KeepLoc == locations.size())
354    return;
355
356  // Keep the smaller location, erase the larger one.
357  unsigned EraseLoc = LocNo;
358  if (KeepLoc > EraseLoc)
359    std::swap(KeepLoc, EraseLoc);
360  locations.erase(locations.begin() + EraseLoc);
361
362  // Rewrite values.
363  for (LocMap::iterator I = locInts.begin(); I.valid(); ++I) {
364    unsigned v = I.value();
365    if (v == EraseLoc)
366      I.setValue(KeepLoc);      // Coalesce when possible.
367    else if (v > EraseLoc)
368      I.setValueUnchecked(v-1); // Avoid coalescing with untransformed values.
369  }
370}
371
372void UserValue::mapVirtRegs(LDVImpl *LDV) {
373  for (unsigned i = 0, e = locations.size(); i != e; ++i)
374    if (locations[i].isReg() &&
375        TargetRegisterInfo::isVirtualRegister(locations[i].getReg()))
376      LDV->mapVirtReg(locations[i].getReg(), this);
377}
378
379UserValue *LDVImpl::getUserValue(const MDNode *Var, unsigned Offset,
380                                 DebugLoc DL) {
381  UserValue *&Leader = userVarMap[Var];
382  if (Leader) {
383    UserValue *UV = Leader->getLeader();
384    Leader = UV;
385    for (; UV; UV = UV->getNext())
386      if (UV->match(Var, Offset))
387        return UV;
388  }
389
390  UserValue *UV = new UserValue(Var, Offset, DL, allocator);
391  userValues.push_back(UV);
392  Leader = UserValue::merge(Leader, UV);
393  return UV;
394}
395
396void LDVImpl::mapVirtReg(unsigned VirtReg, UserValue *EC) {
397  assert(TargetRegisterInfo::isVirtualRegister(VirtReg) && "Only map VirtRegs");
398  UserValue *&Leader = virtRegToEqClass[VirtReg];
399  Leader = UserValue::merge(Leader, EC);
400}
401
402UserValue *LDVImpl::lookupVirtReg(unsigned VirtReg) {
403  if (UserValue *UV = virtRegToEqClass.lookup(VirtReg))
404    return UV->getLeader();
405  return 0;
406}
407
408bool LDVImpl::handleDebugValue(MachineInstr *MI, SlotIndex Idx) {
409  // DBG_VALUE loc, offset, variable
410  if (MI->getNumOperands() != 3 ||
411      !MI->getOperand(1).isImm() || !MI->getOperand(2).isMetadata()) {
412    DEBUG(dbgs() << "Can't handle " << *MI);
413    return false;
414  }
415
416  // Get or create the UserValue for (variable,offset).
417  unsigned Offset = MI->getOperand(1).getImm();
418  const MDNode *Var = MI->getOperand(2).getMetadata();
419  UserValue *UV = getUserValue(Var, Offset, MI->getDebugLoc());
420  UV->addDef(Idx, MI->getOperand(0));
421  return true;
422}
423
424bool LDVImpl::collectDebugValues(MachineFunction &mf) {
425  bool Changed = false;
426  for (MachineFunction::iterator MFI = mf.begin(), MFE = mf.end(); MFI != MFE;
427       ++MFI) {
428    MachineBasicBlock *MBB = MFI;
429    for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
430         MBBI != MBBE;) {
431      if (!MBBI->isDebugValue()) {
432        ++MBBI;
433        continue;
434      }
435      // DBG_VALUE has no slot index, use the previous instruction instead.
436      SlotIndex Idx = MBBI == MBB->begin() ?
437        LIS->getMBBStartIdx(MBB) :
438        LIS->getInstructionIndex(llvm::prior(MBBI)).getDefIndex();
439      // Handle consecutive DBG_VALUE instructions with the same slot index.
440      do {
441        if (handleDebugValue(MBBI, Idx)) {
442          MBBI = MBB->erase(MBBI);
443          Changed = true;
444        } else
445          ++MBBI;
446      } while (MBBI != MBBE && MBBI->isDebugValue());
447    }
448  }
449  return Changed;
450}
451
452void UserValue::extendDef(SlotIndex Idx, unsigned LocNo,
453                          LiveInterval *LI, const VNInfo *VNI,
454                          SmallVectorImpl<SlotIndex> *Kills,
455                          LiveIntervals &LIS, MachineDominatorTree &MDT) {
456  SmallVector<SlotIndex, 16> Todo;
457  Todo.push_back(Idx);
458
459  do {
460    SlotIndex Start = Todo.pop_back_val();
461    MachineBasicBlock *MBB = LIS.getMBBFromIndex(Start);
462    SlotIndex Stop = LIS.getMBBEndIdx(MBB);
463    LocMap::iterator I = locInts.find(Start);
464
465    // Limit to VNI's live range.
466    bool ToEnd = true;
467    if (LI && VNI) {
468      LiveRange *Range = LI->getLiveRangeContaining(Start);
469      if (!Range || Range->valno != VNI) {
470        if (Kills)
471          Kills->push_back(Start);
472        continue;
473      }
474      if (Range->end < Stop)
475        Stop = Range->end, ToEnd = false;
476    }
477
478    // There could already be a short def at Start.
479    if (I.valid() && I.start() <= Start) {
480      // Stop when meeting a different location or an already extended interval.
481      Start = Start.getNextSlot();
482      if (I.value() != LocNo || I.stop() != Start)
483        continue;
484      // This is a one-slot placeholder. Just skip it.
485      ++I;
486    }
487
488    // Limited by the next def.
489    if (I.valid() && I.start() < Stop)
490      Stop = I.start(), ToEnd = false;
491    // Limited by VNI's live range.
492    else if (!ToEnd && Kills)
493      Kills->push_back(Stop);
494
495    if (Start >= Stop)
496      continue;
497
498    I.insert(Start, Stop, LocNo);
499
500    // If we extended to the MBB end, propagate down the dominator tree.
501    if (!ToEnd)
502      continue;
503    const std::vector<MachineDomTreeNode*> &Children =
504      MDT.getNode(MBB)->getChildren();
505    for (unsigned i = 0, e = Children.size(); i != e; ++i)
506      Todo.push_back(LIS.getMBBStartIdx(Children[i]->getBlock()));
507  } while (!Todo.empty());
508}
509
510void
511UserValue::addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
512                      const SmallVectorImpl<SlotIndex> &Kills,
513                      SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
514                      MachineRegisterInfo &MRI, LiveIntervals &LIS) {
515  if (Kills.empty())
516    return;
517  // Don't track copies from physregs, there are too many uses.
518  if (!TargetRegisterInfo::isVirtualRegister(LI->reg))
519    return;
520
521  // Collect all the (vreg, valno) pairs that are copies of LI.
522  SmallVector<std::pair<LiveInterval*, const VNInfo*>, 8> CopyValues;
523  for (MachineRegisterInfo::use_nodbg_iterator
524         UI = MRI.use_nodbg_begin(LI->reg),
525         UE = MRI.use_nodbg_end(); UI != UE; ++UI) {
526    // Copies of the full value.
527    if (UI.getOperand().getSubReg() || !UI->isCopy())
528      continue;
529    MachineInstr *MI = &*UI;
530    unsigned DstReg = MI->getOperand(0).getReg();
531
532    // Don't follow copies to physregs. These are usually setting up call
533    // arguments, and the argument registers are always call clobbered. We are
534    // better off in the source register which could be a callee-saved register,
535    // or it could be spilled.
536    if (!TargetRegisterInfo::isVirtualRegister(DstReg))
537      continue;
538
539    // Is LocNo extended to reach this copy? If not, another def may be blocking
540    // it, or we are looking at a wrong value of LI.
541    SlotIndex Idx = LIS.getInstructionIndex(MI);
542    LocMap::iterator I = locInts.find(Idx.getUseIndex());
543    if (!I.valid() || I.value() != LocNo)
544      continue;
545
546    if (!LIS.hasInterval(DstReg))
547      continue;
548    LiveInterval *DstLI = &LIS.getInterval(DstReg);
549    const VNInfo *DstVNI = DstLI->getVNInfoAt(Idx.getDefIndex());
550    assert(DstVNI && DstVNI->def == Idx.getDefIndex() && "Bad copy value");
551    CopyValues.push_back(std::make_pair(DstLI, DstVNI));
552  }
553
554  if (CopyValues.empty())
555    return;
556
557  DEBUG(dbgs() << "Got " << CopyValues.size() << " copies of " << *LI << '\n');
558
559  // Try to add defs of the copied values for each kill point.
560  for (unsigned i = 0, e = Kills.size(); i != e; ++i) {
561    SlotIndex Idx = Kills[i];
562    for (unsigned j = 0, e = CopyValues.size(); j != e; ++j) {
563      LiveInterval *DstLI = CopyValues[j].first;
564      const VNInfo *DstVNI = CopyValues[j].second;
565      if (DstLI->getVNInfoAt(Idx) != DstVNI)
566        continue;
567      // Check that there isn't already a def at Idx
568      LocMap::iterator I = locInts.find(Idx);
569      if (I.valid() && I.start() <= Idx)
570        continue;
571      DEBUG(dbgs() << "Kill at " << Idx << " covered by valno #"
572                   << DstVNI->id << " in " << *DstLI << '\n');
573      MachineInstr *CopyMI = LIS.getInstructionFromIndex(DstVNI->def);
574      assert(CopyMI && CopyMI->isCopy() && "Bad copy value");
575      unsigned LocNo = getLocationNo(CopyMI->getOperand(0));
576      I.insert(Idx, Idx.getNextSlot(), LocNo);
577      NewDefs.push_back(std::make_pair(Idx, LocNo));
578      break;
579    }
580  }
581}
582
583void
584UserValue::computeIntervals(MachineRegisterInfo &MRI,
585                            LiveIntervals &LIS,
586                            MachineDominatorTree &MDT) {
587  SmallVector<std::pair<SlotIndex, unsigned>, 16> Defs;
588
589  // Collect all defs to be extended (Skipping undefs).
590  for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I)
591    if (I.value() != ~0u)
592      Defs.push_back(std::make_pair(I.start(), I.value()));
593
594  // Extend all defs, and possibly add new ones along the way.
595  for (unsigned i = 0; i != Defs.size(); ++i) {
596    SlotIndex Idx = Defs[i].first;
597    unsigned LocNo = Defs[i].second;
598    const MachineOperand &Loc = locations[LocNo];
599
600    // Register locations are constrained to where the register value is live.
601    if (Loc.isReg() && LIS.hasInterval(Loc.getReg())) {
602      LiveInterval *LI = &LIS.getInterval(Loc.getReg());
603      const VNInfo *VNI = LI->getVNInfoAt(Idx);
604      SmallVector<SlotIndex, 16> Kills;
605      extendDef(Idx, LocNo, LI, VNI, &Kills, LIS, MDT);
606      addDefsFromCopies(LI, LocNo, Kills, Defs, MRI, LIS);
607    } else
608      extendDef(Idx, LocNo, 0, 0, 0, LIS, MDT);
609  }
610
611  // Finally, erase all the undefs.
612  for (LocMap::iterator I = locInts.begin(); I.valid();)
613    if (I.value() == ~0u)
614      I.erase();
615    else
616      ++I;
617}
618
619void LDVImpl::computeIntervals() {
620  for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
621    userValues[i]->computeIntervals(MF->getRegInfo(), *LIS, *MDT);
622    userValues[i]->mapVirtRegs(this);
623  }
624}
625
626bool LDVImpl::runOnMachineFunction(MachineFunction &mf) {
627  MF = &mf;
628  LIS = &pass.getAnalysis<LiveIntervals>();
629  MDT = &pass.getAnalysis<MachineDominatorTree>();
630  TRI = mf.getTarget().getRegisterInfo();
631  clear();
632  DEBUG(dbgs() << "********** COMPUTING LIVE DEBUG VARIABLES: "
633               << ((Value*)mf.getFunction())->getName()
634               << " **********\n");
635
636  bool Changed = collectDebugValues(mf);
637  computeIntervals();
638  DEBUG(print(dbgs()));
639  return Changed;
640}
641
642bool LiveDebugVariables::runOnMachineFunction(MachineFunction &mf) {
643  if (!EnableLDV)
644    return false;
645  if (!pImpl)
646    pImpl = new LDVImpl(this);
647  return static_cast<LDVImpl*>(pImpl)->runOnMachineFunction(mf);
648}
649
650void LiveDebugVariables::releaseMemory() {
651  if (pImpl)
652    static_cast<LDVImpl*>(pImpl)->clear();
653}
654
655LiveDebugVariables::~LiveDebugVariables() {
656  if (pImpl)
657    delete static_cast<LDVImpl*>(pImpl);
658}
659
660void UserValue::
661renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx,
662               const TargetRegisterInfo *TRI) {
663  for (unsigned i = locations.size(); i; --i) {
664    unsigned LocNo = i - 1;
665    MachineOperand &Loc = locations[LocNo];
666    if (!Loc.isReg() || Loc.getReg() != OldReg)
667      continue;
668    if (TargetRegisterInfo::isPhysicalRegister(NewReg))
669      Loc.substPhysReg(NewReg, *TRI);
670    else
671      Loc.substVirtReg(NewReg, SubIdx, *TRI);
672    coalesceLocation(LocNo);
673  }
674}
675
676void LDVImpl::
677renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx) {
678  UserValue *UV = lookupVirtReg(OldReg);
679  if (!UV)
680    return;
681
682  if (TargetRegisterInfo::isVirtualRegister(NewReg))
683    mapVirtReg(NewReg, UV);
684  virtRegToEqClass.erase(OldReg);
685
686  do {
687    UV->renameRegister(OldReg, NewReg, SubIdx, TRI);
688    UV = UV->getNext();
689  } while (UV);
690}
691
692void LiveDebugVariables::
693renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx) {
694  if (pImpl)
695    static_cast<LDVImpl*>(pImpl)->renameRegister(OldReg, NewReg, SubIdx);
696}
697
698//===----------------------------------------------------------------------===//
699//                           Live Range Splitting
700//===----------------------------------------------------------------------===//
701
702bool
703UserValue::splitLocation(unsigned OldLocNo, ArrayRef<LiveInterval*> NewRegs) {
704  DEBUG({
705    dbgs() << "Splitting Loc" << OldLocNo << '\t';
706    print(dbgs(), 0);
707  });
708  bool DidChange = false;
709  LocMap::iterator LocMapI;
710  LocMapI.setMap(locInts);
711  for (unsigned i = 0; i != NewRegs.size(); ++i) {
712    LiveInterval *LI = NewRegs[i];
713    if (LI->empty())
714      continue;
715
716    // Don't allocate the new LocNo until it is needed.
717    unsigned NewLocNo = ~0u;
718
719    // Iterate over the overlaps between locInts and LI.
720    LocMapI.find(LI->beginIndex());
721    if (!LocMapI.valid())
722      continue;
723    LiveInterval::iterator LII = LI->advanceTo(LI->begin(), LocMapI.start());
724    LiveInterval::iterator LIE = LI->end();
725    while (LocMapI.valid() && LII != LIE) {
726      // At this point, we know that LocMapI.stop() > LII->start.
727      LII = LI->advanceTo(LII, LocMapI.start());
728      if (LII == LIE)
729        break;
730
731      // Now LII->end > LocMapI.start(). Do we have an overlap?
732      if (LocMapI.value() == OldLocNo && LII->start < LocMapI.stop()) {
733        // Overlapping correct location. Allocate NewLocNo now.
734        if (NewLocNo == ~0u) {
735          MachineOperand MO = MachineOperand::CreateReg(LI->reg, false);
736          MO.setSubReg(locations[OldLocNo].getSubReg());
737          NewLocNo = getLocationNo(MO);
738          DidChange = true;
739        }
740
741        SlotIndex LStart = LocMapI.start();
742        SlotIndex LStop  = LocMapI.stop();
743
744        // Trim LocMapI down to the LII overlap.
745        if (LStart < LII->start)
746          LocMapI.setStartUnchecked(LII->start);
747        if (LStop > LII->end)
748          LocMapI.setStopUnchecked(LII->end);
749
750        // Change the value in the overlap. This may trigger coalescing.
751        LocMapI.setValue(NewLocNo);
752
753        // Re-insert any removed OldLocNo ranges.
754        if (LStart < LocMapI.start()) {
755          LocMapI.insert(LStart, LocMapI.start(), OldLocNo);
756          ++LocMapI;
757          assert(LocMapI.valid() && "Unexpected coalescing");
758        }
759        if (LStop > LocMapI.stop()) {
760          ++LocMapI;
761          LocMapI.insert(LII->end, LStop, OldLocNo);
762          --LocMapI;
763        }
764      }
765
766      // Advance to the next overlap.
767      if (LII->end < LocMapI.stop()) {
768        if (++LII == LIE)
769          break;
770        LocMapI.advanceTo(LII->start);
771      } else {
772        ++LocMapI;
773        if (!LocMapI.valid())
774          break;
775        LII = LI->advanceTo(LII, LocMapI.start());
776      }
777    }
778  }
779
780  // Finally, remove any remaining OldLocNo intervals and OldLocNo itself.
781  locations.erase(locations.begin() + OldLocNo);
782  LocMapI.goToBegin();
783  while (LocMapI.valid()) {
784    unsigned v = LocMapI.value();
785    if (v == OldLocNo) {
786      DEBUG(dbgs() << "Erasing [" << LocMapI.start() << ';'
787                   << LocMapI.stop() << ")\n");
788      LocMapI.erase();
789    } else {
790      if (v > OldLocNo)
791        LocMapI.setValueUnchecked(v-1);
792      ++LocMapI;
793    }
794  }
795
796  DEBUG({dbgs() << "Split result: \t"; print(dbgs(), 0);});
797  return DidChange;
798}
799
800bool
801UserValue::splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs) {
802  bool DidChange = false;
803  // Split locations referring to OldReg. Iterate backwards so splitLocation can
804  // safely erase unuused locations.
805  for (unsigned i = locations.size(); i ; --i) {
806    unsigned LocNo = i-1;
807    const MachineOperand *Loc = &locations[LocNo];
808    if (!Loc->isReg() || Loc->getReg() != OldReg)
809      continue;
810    DidChange |= splitLocation(LocNo, NewRegs);
811  }
812  return DidChange;
813}
814
815void LDVImpl::splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs) {
816  bool DidChange = false;
817  for (UserValue *UV = lookupVirtReg(OldReg); UV; UV = UV->getNext())
818    DidChange |= UV->splitRegister(OldReg, NewRegs);
819
820  if (!DidChange)
821    return;
822
823  // Map all of the new virtual registers.
824  UserValue *UV = lookupVirtReg(OldReg);
825  for (unsigned i = 0; i != NewRegs.size(); ++i)
826    mapVirtReg(NewRegs[i]->reg, UV);
827}
828
829void LiveDebugVariables::
830splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs) {
831  if (pImpl)
832    static_cast<LDVImpl*>(pImpl)->splitRegister(OldReg, NewRegs);
833}
834
835void
836UserValue::rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI) {
837  // Iterate over locations in reverse makes it easier to handle coalescing.
838  for (unsigned i = locations.size(); i ; --i) {
839    unsigned LocNo = i-1;
840    MachineOperand &Loc = locations[LocNo];
841    // Only virtual registers are rewritten.
842    if (!Loc.isReg() || !Loc.getReg() ||
843        !TargetRegisterInfo::isVirtualRegister(Loc.getReg()))
844      continue;
845    unsigned VirtReg = Loc.getReg();
846    if (VRM.isAssignedReg(VirtReg) &&
847        TargetRegisterInfo::isPhysicalRegister(VRM.getPhys(VirtReg))) {
848      // This can create a %noreg operand in rare cases when the sub-register
849      // index is no longer available. That means the user value is in a
850      // non-existent sub-register, and %noreg is exactly what we want.
851      Loc.substPhysReg(VRM.getPhys(VirtReg), TRI);
852    } else if (VRM.getStackSlot(VirtReg) != VirtRegMap::NO_STACK_SLOT &&
853               VRM.isSpillSlotUsed(VRM.getStackSlot(VirtReg))) {
854      // FIXME: Translate SubIdx to a stackslot offset.
855      Loc = MachineOperand::CreateFI(VRM.getStackSlot(VirtReg));
856    } else {
857      Loc.setReg(0);
858      Loc.setSubReg(0);
859    }
860    coalesceLocation(LocNo);
861  }
862}
863
864/// findInsertLocation - Find an iterator for inserting a DBG_VALUE
865/// instruction.
866static MachineBasicBlock::iterator
867findInsertLocation(MachineBasicBlock *MBB, SlotIndex Idx,
868                   LiveIntervals &LIS) {
869  SlotIndex Start = LIS.getMBBStartIdx(MBB);
870  Idx = Idx.getBaseIndex();
871
872  // Try to find an insert location by going backwards from Idx.
873  MachineInstr *MI;
874  while (!(MI = LIS.getInstructionFromIndex(Idx))) {
875    // We've reached the beginning of MBB.
876    if (Idx == Start) {
877      MachineBasicBlock::iterator I = MBB->SkipPHIsAndLabels(MBB->begin());
878      return I;
879    }
880    Idx = Idx.getPrevIndex();
881  }
882
883  // Don't insert anything after the first terminator, though.
884  return MI->getDesc().isTerminator() ? MBB->getFirstTerminator() :
885                                    llvm::next(MachineBasicBlock::iterator(MI));
886}
887
888DebugLoc UserValue::findDebugLoc() {
889  DebugLoc D = dl;
890  dl = DebugLoc();
891  return D;
892}
893void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx,
894                                 unsigned LocNo,
895                                 LiveIntervals &LIS,
896                                 const TargetInstrInfo &TII) {
897  MachineBasicBlock::iterator I = findInsertLocation(MBB, Idx, LIS);
898  MachineOperand &Loc = locations[LocNo];
899
900  // Frame index locations may require a target callback.
901  if (Loc.isFI()) {
902    MachineInstr *MI = TII.emitFrameIndexDebugValue(*MBB->getParent(),
903                                          Loc.getIndex(), offset, variable,
904                                                    findDebugLoc());
905    if (MI) {
906      MBB->insert(I, MI);
907      return;
908    }
909  }
910  // This is not a frame index, or the target is happy with a standard FI.
911  BuildMI(*MBB, I, findDebugLoc(), TII.get(TargetOpcode::DBG_VALUE))
912    .addOperand(Loc).addImm(offset).addMetadata(variable);
913}
914
915void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
916                                const TargetInstrInfo &TII) {
917  MachineFunction::iterator MFEnd = VRM->getMachineFunction().end();
918
919  for (LocMap::const_iterator I = locInts.begin(); I.valid();) {
920    SlotIndex Start = I.start();
921    SlotIndex Stop = I.stop();
922    unsigned LocNo = I.value();
923    DEBUG(dbgs() << "\t[" << Start << ';' << Stop << "):" << LocNo);
924    MachineFunction::iterator MBB = LIS.getMBBFromIndex(Start);
925    SlotIndex MBBEnd = LIS.getMBBEndIdx(MBB);
926
927    DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
928    insertDebugValue(MBB, Start, LocNo, LIS, TII);
929    ++NumInsertedDebugValues;
930    // This interval may span multiple basic blocks.
931    // Insert a DBG_VALUE into each one.
932    while(Stop > MBBEnd) {
933      // Move to the next block.
934      Start = MBBEnd;
935      if (++MBB == MFEnd)
936        break;
937      MBBEnd = LIS.getMBBEndIdx(MBB);
938      DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
939      insertDebugValue(MBB, Start, LocNo, LIS, TII);
940      ++NumInsertedDebugValues;
941    }
942    DEBUG(dbgs() << '\n');
943    if (MBB == MFEnd)
944      break;
945
946    ++I;
947  }
948}
949
950void LDVImpl::emitDebugValues(VirtRegMap *VRM) {
951  DEBUG(dbgs() << "********** EMITTING LIVE DEBUG VARIABLES **********\n");
952  const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
953  for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
954    DEBUG(userValues[i]->print(dbgs(), &MF->getTarget()));
955    userValues[i]->rewriteLocations(*VRM, *TRI);
956    userValues[i]->emitDebugValues(VRM, *LIS, *TII);
957  }
958}
959
960void LiveDebugVariables::emitDebugValues(VirtRegMap *VRM) {
961  if (pImpl)
962    static_cast<LDVImpl*>(pImpl)->emitDebugValues(VRM);
963}
964
965
966#ifndef NDEBUG
967void LiveDebugVariables::dump() {
968  if (pImpl)
969    static_cast<LDVImpl*>(pImpl)->print(dbgs());
970}
971#endif
972
973