LiveDebugVariables.cpp revision 3517640443f0b5224e2a6414c246ac60016ee9d4 
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  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  bool IsIndirect;        ///< true if this is a register-indirect+offset value.
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, bool i, DebugLoc L,
139            LocMap::Allocator &alloc)
140    : variable(var), offset(o), IsIndirect(i), dl(L), leader(this),
141      next(0), locInts(alloc)
142  {}
143
144  /// getLeader - Get the leader of this value's equivalence class.
145  UserValue *getLeader() {
146    UserValue *l = leader;
147    while (l != l->leader)
148      l = l->leader;
149    return leader = l;
150  }
151
152  /// getNext - Return the next UserValue in the equivalence class.
153  UserValue *getNext() const { return next; }
154
155  /// match - Does this UserValue match the parameters?
156  bool match(const MDNode *Var, unsigned Offset) const {
157    return Var == variable && Offset == offset;
158  }
159
160  /// merge - Merge equivalence classes.
161  static UserValue *merge(UserValue *L1, UserValue *L2) {
162    L2 = L2->getLeader();
163    if (!L1)
164      return L2;
165    L1 = L1->getLeader();
166    if (L1 == L2)
167      return L1;
168    // Splice L2 before L1's members.
169    UserValue *End = L2;
170    while (End->next)
171      End->leader = L1, End = End->next;
172    End->leader = L1;
173    End->next = L1->next;
174    L1->next = L2;
175    return L1;
176  }
177
178  /// getLocationNo - Return the location number that matches Loc.
179  unsigned getLocationNo(const MachineOperand &LocMO) {
180    if (LocMO.isReg()) {
181      if (LocMO.getReg() == 0)
182        return ~0u;
183      // For register locations we dont care about use/def and other flags.
184      for (unsigned i = 0, e = locations.size(); i != e; ++i)
185        if (locations[i].isReg() &&
186            locations[i].getReg() == LocMO.getReg() &&
187            locations[i].getSubReg() == LocMO.getSubReg())
188          return i;
189    } else
190      for (unsigned i = 0, e = locations.size(); i != e; ++i)
191        if (LocMO.isIdenticalTo(locations[i]))
192          return i;
193    locations.push_back(LocMO);
194    // We are storing a MachineOperand outside a MachineInstr.
195    locations.back().clearParent();
196    // Don't store def operands.
197    if (locations.back().isReg())
198      locations.back().setIsUse();
199    return locations.size() - 1;
200  }
201
202  /// mapVirtRegs - Ensure that all virtual register locations are mapped.
203  void mapVirtRegs(LDVImpl *LDV);
204
205  /// addDef - Add a definition point to this value.
206  void addDef(SlotIndex Idx, const MachineOperand &LocMO) {
207    // Add a singular (Idx,Idx) -> Loc mapping.
208    LocMap::iterator I = locInts.find(Idx);
209    if (!I.valid() || I.start() != Idx)
210      I.insert(Idx, Idx.getNextSlot(), getLocationNo(LocMO));
211    else
212      // A later DBG_VALUE at the same SlotIndex overrides the old location.
213      I.setValue(getLocationNo(LocMO));
214  }
215
216  /// extendDef - Extend the current definition as far as possible down the
217  /// dominator tree. Stop when meeting an existing def or when leaving the live
218  /// range of VNI.
219  /// End points where VNI is no longer live are added to Kills.
220  /// @param Idx   Starting point for the definition.
221  /// @param LocNo Location number to propagate.
222  /// @param LI    Restrict liveness to where LI has the value VNI. May be null.
223  /// @param VNI   When LI is not null, this is the value to restrict to.
224  /// @param Kills Append end points of VNI's live range to Kills.
225  /// @param LIS   Live intervals analysis.
226  /// @param MDT   Dominator tree.
227  void extendDef(SlotIndex Idx, unsigned LocNo,
228                 LiveInterval *LI, const VNInfo *VNI,
229                 SmallVectorImpl<SlotIndex> *Kills,
230                 LiveIntervals &LIS, MachineDominatorTree &MDT,
231                 UserValueScopes &UVS);
232
233  /// addDefsFromCopies - The value in LI/LocNo may be copies to other
234  /// registers. Determine if any of the copies are available at the kill
235  /// points, and add defs if possible.
236  /// @param LI      Scan for copies of the value in LI->reg.
237  /// @param LocNo   Location number of LI->reg.
238  /// @param Kills   Points where the range of LocNo could be extended.
239  /// @param NewDefs Append (Idx, LocNo) of inserted defs here.
240  void addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
241                      const SmallVectorImpl<SlotIndex> &Kills,
242                      SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
243                      MachineRegisterInfo &MRI,
244                      LiveIntervals &LIS);
245
246  /// computeIntervals - Compute the live intervals of all locations after
247  /// collecting all their def points.
248  void computeIntervals(MachineRegisterInfo &MRI, const TargetRegisterInfo &TRI,
249                        LiveIntervals &LIS, MachineDominatorTree &MDT,
250                        UserValueScopes &UVS);
251
252  /// splitRegister - Replace OldReg ranges with NewRegs ranges where NewRegs is
253  /// live. Returns true if any changes were made.
254  bool splitRegister(unsigned OldLocNo, ArrayRef<LiveInterval*> NewRegs);
255
256  /// rewriteLocations - Rewrite virtual register locations according to the
257  /// provided virtual register map.
258  void rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI);
259
260  /// emitDebugValues - Recreate DBG_VALUE instruction from data structures.
261  void emitDebugValues(VirtRegMap *VRM,
262                       LiveIntervals &LIS, const TargetInstrInfo &TRI);
263
264  /// findDebugLoc - Return DebugLoc used for this DBG_VALUE instruction. A
265  /// variable may have more than one corresponding DBG_VALUE instructions.
266  /// Only first one needs DebugLoc to identify variable's lexical scope
267  /// in source file.
268  DebugLoc findDebugLoc();
269
270  /// getDebugLoc - Return DebugLoc of this UserValue.
271  DebugLoc getDebugLoc() { return dl;}
272  void print(raw_ostream&, const TargetMachine*);
273};
274} // namespace
275
276/// LDVImpl - Implementation of the LiveDebugVariables pass.
277namespace {
278class LDVImpl {
279  LiveDebugVariables &pass;
280  LocMap::Allocator allocator;
281  MachineFunction *MF;
282  LiveIntervals *LIS;
283  LexicalScopes LS;
284  MachineDominatorTree *MDT;
285  const TargetRegisterInfo *TRI;
286
287  /// Whether emitDebugValues is called.
288  bool EmitDone;
289  /// Whether the machine function is modified during the pass.
290  bool ModifiedMF;
291
292  /// userValues - All allocated UserValue instances.
293  SmallVector<UserValue*, 8> userValues;
294
295  /// Map virtual register to eq class leader.
296  typedef DenseMap<unsigned, UserValue*> VRMap;
297  VRMap virtRegToEqClass;
298
299  /// Map user variable to eq class leader.
300  typedef DenseMap<const MDNode *, UserValue*> UVMap;
301  UVMap userVarMap;
302
303  /// getUserValue - Find or create a UserValue.
304  UserValue *getUserValue(const MDNode *Var, unsigned Offset,
305                          bool IsIndirect, DebugLoc DL);
306
307  /// lookupVirtReg - Find the EC leader for VirtReg or null.
308  UserValue *lookupVirtReg(unsigned VirtReg);
309
310  /// handleDebugValue - Add DBG_VALUE instruction to our maps.
311  /// @param MI  DBG_VALUE instruction
312  /// @param Idx Last valid SLotIndex before instruction.
313  /// @return    True if the DBG_VALUE instruction should be deleted.
314  bool handleDebugValue(MachineInstr *MI, SlotIndex Idx);
315
316  /// collectDebugValues - Collect and erase all DBG_VALUE instructions, adding
317  /// a UserValue def for each instruction.
318  /// @param mf MachineFunction to be scanned.
319  /// @return True if any debug values were found.
320  bool collectDebugValues(MachineFunction &mf);
321
322  /// computeIntervals - Compute the live intervals of all user values after
323  /// collecting all their def points.
324  void computeIntervals();
325
326public:
327  LDVImpl(LiveDebugVariables *ps) : pass(*ps), EmitDone(false),
328                                    ModifiedMF(false) {}
329  bool runOnMachineFunction(MachineFunction &mf);
330
331  /// clear - Release all memory.
332  void clear() {
333    DeleteContainerPointers(userValues);
334    userValues.clear();
335    virtRegToEqClass.clear();
336    userVarMap.clear();
337    // Make sure we call emitDebugValues if the machine function was modified.
338    assert((!ModifiedMF || EmitDone) &&
339           "Dbg values are not emitted in LDV");
340    EmitDone = false;
341    ModifiedMF = false;
342  }
343
344  /// mapVirtReg - Map virtual register to an equivalence class.
345  void mapVirtReg(unsigned VirtReg, UserValue *EC);
346
347  /// splitRegister -  Replace all references to OldReg with NewRegs.
348  void splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs);
349
350  /// emitDebugValues - Recreate DBG_VALUE instruction from data structures.
351  void emitDebugValues(VirtRegMap *VRM);
352
353  void print(raw_ostream&);
354};
355} // namespace
356
357void UserValue::print(raw_ostream &OS, const TargetMachine *TM) {
358  DIVariable DV(variable);
359  OS << "!\"";
360  DV.printExtendedName(OS);
361  OS << "\"\t";
362  if (offset)
363    OS << '+' << offset;
364  for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) {
365    OS << " [" << I.start() << ';' << I.stop() << "):";
366    if (I.value() == ~0u)
367      OS << "undef";
368    else
369      OS << I.value();
370  }
371  for (unsigned i = 0, e = locations.size(); i != e; ++i) {
372    OS << " Loc" << i << '=';
373    locations[i].print(OS, TM);
374  }
375  OS << '\n';
376}
377
378void LDVImpl::print(raw_ostream &OS) {
379  OS << "********** DEBUG VARIABLES **********\n";
380  for (unsigned i = 0, e = userValues.size(); i != e; ++i)
381    userValues[i]->print(OS, &MF->getTarget());
382}
383
384void UserValue::coalesceLocation(unsigned LocNo) {
385  unsigned KeepLoc = 0;
386  for (unsigned e = locations.size(); KeepLoc != e; ++KeepLoc) {
387    if (KeepLoc == LocNo)
388      continue;
389    if (locations[KeepLoc].isIdenticalTo(locations[LocNo]))
390      break;
391  }
392  // No matches.
393  if (KeepLoc == locations.size())
394    return;
395
396  // Keep the smaller location, erase the larger one.
397  unsigned EraseLoc = LocNo;
398  if (KeepLoc > EraseLoc)
399    std::swap(KeepLoc, EraseLoc);
400  locations.erase(locations.begin() + EraseLoc);
401
402  // Rewrite values.
403  for (LocMap::iterator I = locInts.begin(); I.valid(); ++I) {
404    unsigned v = I.value();
405    if (v == EraseLoc)
406      I.setValue(KeepLoc);      // Coalesce when possible.
407    else if (v > EraseLoc)
408      I.setValueUnchecked(v-1); // Avoid coalescing with untransformed values.
409  }
410}
411
412void UserValue::mapVirtRegs(LDVImpl *LDV) {
413  for (unsigned i = 0, e = locations.size(); i != e; ++i)
414    if (locations[i].isReg() &&
415        TargetRegisterInfo::isVirtualRegister(locations[i].getReg()))
416      LDV->mapVirtReg(locations[i].getReg(), this);
417}
418
419UserValue *LDVImpl::getUserValue(const MDNode *Var, unsigned Offset,
420                                 bool IsIndirect, DebugLoc DL) {
421  UserValue *&Leader = userVarMap[Var];
422  if (Leader) {
423    UserValue *UV = Leader->getLeader();
424    Leader = UV;
425    for (; UV; UV = UV->getNext())
426      if (UV->match(Var, Offset))
427        return UV;
428  }
429
430  UserValue *UV = new UserValue(Var, Offset, IsIndirect, DL, allocator);
431  userValues.push_back(UV);
432  Leader = UserValue::merge(Leader, UV);
433  return UV;
434}
435
436void LDVImpl::mapVirtReg(unsigned VirtReg, UserValue *EC) {
437  assert(TargetRegisterInfo::isVirtualRegister(VirtReg) && "Only map VirtRegs");
438  UserValue *&Leader = virtRegToEqClass[VirtReg];
439  Leader = UserValue::merge(Leader, EC);
440}
441
442UserValue *LDVImpl::lookupVirtReg(unsigned VirtReg) {
443  if (UserValue *UV = virtRegToEqClass.lookup(VirtReg))
444    return UV->getLeader();
445  return 0;
446}
447
448bool LDVImpl::handleDebugValue(MachineInstr *MI, SlotIndex Idx) {
449  // DBG_VALUE loc, offset, variable
450  if (MI->getNumOperands() != 3 ||
451      !(MI->getOperand(1).isReg() || MI->getOperand(1).isImm()) ||
452      !MI->getOperand(2).isMetadata()) {
453    DEBUG(dbgs() << "Can't handle " << *MI);
454    return false;
455  }
456
457  // Get or create the UserValue for (variable,offset).
458  bool IsIndirect = MI->getOperand(1).isImm();
459  unsigned Offset = IsIndirect ? MI->getOperand(1).getImm() : 0;
460  const MDNode *Var = MI->getOperand(2).getMetadata();
461  UserValue *UV = getUserValue(Var, Offset, IsIndirect, MI->getDebugLoc());
462  UV->addDef(Idx, MI->getOperand(0));
463  return true;
464}
465
466bool LDVImpl::collectDebugValues(MachineFunction &mf) {
467  bool Changed = false;
468  for (MachineFunction::iterator MFI = mf.begin(), MFE = mf.end(); MFI != MFE;
469       ++MFI) {
470    MachineBasicBlock *MBB = MFI;
471    for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
472         MBBI != MBBE;) {
473      if (!MBBI->isDebugValue()) {
474        ++MBBI;
475        continue;
476      }
477      // DBG_VALUE has no slot index, use the previous instruction instead.
478      SlotIndex Idx = MBBI == MBB->begin() ?
479        LIS->getMBBStartIdx(MBB) :
480        LIS->getInstructionIndex(llvm::prior(MBBI)).getRegSlot();
481      // Handle consecutive DBG_VALUE instructions with the same slot index.
482      do {
483        if (handleDebugValue(MBBI, Idx)) {
484          MBBI = MBB->erase(MBBI);
485          Changed = true;
486        } else
487          ++MBBI;
488      } while (MBBI != MBBE && MBBI->isDebugValue());
489    }
490  }
491  return Changed;
492}
493
494void UserValue::extendDef(SlotIndex Idx, unsigned LocNo,
495                          LiveInterval *LI, const VNInfo *VNI,
496                          SmallVectorImpl<SlotIndex> *Kills,
497                          LiveIntervals &LIS, MachineDominatorTree &MDT,
498                          UserValueScopes &UVS) {
499  SmallVector<SlotIndex, 16> Todo;
500  Todo.push_back(Idx);
501  do {
502    SlotIndex Start = Todo.pop_back_val();
503    MachineBasicBlock *MBB = LIS.getMBBFromIndex(Start);
504    SlotIndex Stop = LIS.getMBBEndIdx(MBB);
505    LocMap::iterator I = locInts.find(Start);
506
507    // Limit to VNI's live range.
508    bool ToEnd = true;
509    if (LI && VNI) {
510      LiveRange *Range = LI->getLiveRangeContaining(Start);
511      if (!Range || Range->valno != VNI) {
512        if (Kills)
513          Kills->push_back(Start);
514        continue;
515      }
516      if (Range->end < Stop)
517        Stop = Range->end, ToEnd = false;
518    }
519
520    // There could already be a short def at Start.
521    if (I.valid() && I.start() <= Start) {
522      // Stop when meeting a different location or an already extended interval.
523      Start = Start.getNextSlot();
524      if (I.value() != LocNo || I.stop() != Start)
525        continue;
526      // This is a one-slot placeholder. Just skip it.
527      ++I;
528    }
529
530    // Limited by the next def.
531    if (I.valid() && I.start() < Stop)
532      Stop = I.start(), ToEnd = false;
533    // Limited by VNI's live range.
534    else if (!ToEnd && Kills)
535      Kills->push_back(Stop);
536
537    if (Start >= Stop)
538      continue;
539
540    I.insert(Start, Stop, LocNo);
541
542    // If we extended to the MBB end, propagate down the dominator tree.
543    if (!ToEnd)
544      continue;
545    const std::vector<MachineDomTreeNode*> &Children =
546      MDT.getNode(MBB)->getChildren();
547    for (unsigned i = 0, e = Children.size(); i != e; ++i) {
548      MachineBasicBlock *MBB = Children[i]->getBlock();
549      if (UVS.dominates(MBB))
550        Todo.push_back(LIS.getMBBStartIdx(MBB));
551    }
552  } while (!Todo.empty());
553}
554
555void
556UserValue::addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
557                      const SmallVectorImpl<SlotIndex> &Kills,
558                      SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
559                      MachineRegisterInfo &MRI, LiveIntervals &LIS) {
560  if (Kills.empty())
561    return;
562  // Don't track copies from physregs, there are too many uses.
563  if (!TargetRegisterInfo::isVirtualRegister(LI->reg))
564    return;
565
566  // Collect all the (vreg, valno) pairs that are copies of LI.
567  SmallVector<std::pair<LiveInterval*, const VNInfo*>, 8> CopyValues;
568  for (MachineRegisterInfo::use_nodbg_iterator
569         UI = MRI.use_nodbg_begin(LI->reg),
570         UE = MRI.use_nodbg_end(); UI != UE; ++UI) {
571    // Copies of the full value.
572    if (UI.getOperand().getSubReg() || !UI->isCopy())
573      continue;
574    MachineInstr *MI = &*UI;
575    unsigned DstReg = MI->getOperand(0).getReg();
576
577    // Don't follow copies to physregs. These are usually setting up call
578    // arguments, and the argument registers are always call clobbered. We are
579    // better off in the source register which could be a callee-saved register,
580    // or it could be spilled.
581    if (!TargetRegisterInfo::isVirtualRegister(DstReg))
582      continue;
583
584    // Is LocNo extended to reach this copy? If not, another def may be blocking
585    // it, or we are looking at a wrong value of LI.
586    SlotIndex Idx = LIS.getInstructionIndex(MI);
587    LocMap::iterator I = locInts.find(Idx.getRegSlot(true));
588    if (!I.valid() || I.value() != LocNo)
589      continue;
590
591    if (!LIS.hasInterval(DstReg))
592      continue;
593    LiveInterval *DstLI = &LIS.getInterval(DstReg);
594    const VNInfo *DstVNI = DstLI->getVNInfoAt(Idx.getRegSlot());
595    assert(DstVNI && DstVNI->def == Idx.getRegSlot() && "Bad copy value");
596    CopyValues.push_back(std::make_pair(DstLI, DstVNI));
597  }
598
599  if (CopyValues.empty())
600    return;
601
602  DEBUG(dbgs() << "Got " << CopyValues.size() << " copies of " << *LI << '\n');
603
604  // Try to add defs of the copied values for each kill point.
605  for (unsigned i = 0, e = Kills.size(); i != e; ++i) {
606    SlotIndex Idx = Kills[i];
607    for (unsigned j = 0, e = CopyValues.size(); j != e; ++j) {
608      LiveInterval *DstLI = CopyValues[j].first;
609      const VNInfo *DstVNI = CopyValues[j].second;
610      if (DstLI->getVNInfoAt(Idx) != DstVNI)
611        continue;
612      // Check that there isn't already a def at Idx
613      LocMap::iterator I = locInts.find(Idx);
614      if (I.valid() && I.start() <= Idx)
615        continue;
616      DEBUG(dbgs() << "Kill at " << Idx << " covered by valno #"
617                   << DstVNI->id << " in " << *DstLI << '\n');
618      MachineInstr *CopyMI = LIS.getInstructionFromIndex(DstVNI->def);
619      assert(CopyMI && CopyMI->isCopy() && "Bad copy value");
620      unsigned LocNo = getLocationNo(CopyMI->getOperand(0));
621      I.insert(Idx, Idx.getNextSlot(), LocNo);
622      NewDefs.push_back(std::make_pair(Idx, LocNo));
623      break;
624    }
625  }
626}
627
628void
629UserValue::computeIntervals(MachineRegisterInfo &MRI,
630                            const TargetRegisterInfo &TRI,
631                            LiveIntervals &LIS,
632                            MachineDominatorTree &MDT,
633                            UserValueScopes &UVS) {
634  SmallVector<std::pair<SlotIndex, unsigned>, 16> Defs;
635
636  // Collect all defs to be extended (Skipping undefs).
637  for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I)
638    if (I.value() != ~0u)
639      Defs.push_back(std::make_pair(I.start(), I.value()));
640
641  // Extend all defs, and possibly add new ones along the way.
642  for (unsigned i = 0; i != Defs.size(); ++i) {
643    SlotIndex Idx = Defs[i].first;
644    unsigned LocNo = Defs[i].second;
645    const MachineOperand &Loc = locations[LocNo];
646
647    if (!Loc.isReg()) {
648      extendDef(Idx, LocNo, 0, 0, 0, LIS, MDT, UVS);
649      continue;
650    }
651
652    // Register locations are constrained to where the register value is live.
653    if (TargetRegisterInfo::isVirtualRegister(Loc.getReg())) {
654      LiveInterval *LI = 0;
655      const VNInfo *VNI = 0;
656      if (LIS.hasInterval(Loc.getReg())) {
657        LI = &LIS.getInterval(Loc.getReg());
658        VNI = LI->getVNInfoAt(Idx);
659      }
660      SmallVector<SlotIndex, 16> Kills;
661      extendDef(Idx, LocNo, LI, VNI, &Kills, LIS, MDT, UVS);
662      if (LI)
663        addDefsFromCopies(LI, LocNo, Kills, Defs, MRI, LIS);
664      continue;
665    }
666
667    // For physregs, use the live range of the first regunit as a guide.
668    unsigned Unit = *MCRegUnitIterator(Loc.getReg(), &TRI);
669    LiveInterval *LI = &LIS.getRegUnit(Unit);
670    const VNInfo *VNI = LI->getVNInfoAt(Idx);
671    // Don't track copies from physregs, it is too expensive.
672    extendDef(Idx, LocNo, LI, VNI, 0, LIS, MDT, UVS);
673  }
674
675  // Finally, erase all the undefs.
676  for (LocMap::iterator I = locInts.begin(); I.valid();)
677    if (I.value() == ~0u)
678      I.erase();
679    else
680      ++I;
681}
682
683void LDVImpl::computeIntervals() {
684  for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
685    UserValueScopes UVS(userValues[i]->getDebugLoc(), LS);
686    userValues[i]->computeIntervals(MF->getRegInfo(), *TRI, *LIS, *MDT, UVS);
687    userValues[i]->mapVirtRegs(this);
688  }
689}
690
691bool LDVImpl::runOnMachineFunction(MachineFunction &mf) {
692  MF = &mf;
693  LIS = &pass.getAnalysis<LiveIntervals>();
694  MDT = &pass.getAnalysis<MachineDominatorTree>();
695  TRI = mf.getTarget().getRegisterInfo();
696  clear();
697  LS.initialize(mf);
698  DEBUG(dbgs() << "********** COMPUTING LIVE DEBUG VARIABLES: "
699               << mf.getName() << " **********\n");
700
701  bool Changed = collectDebugValues(mf);
702  computeIntervals();
703  DEBUG(print(dbgs()));
704  LS.releaseMemory();
705  ModifiedMF = Changed;
706  return Changed;
707}
708
709bool LiveDebugVariables::runOnMachineFunction(MachineFunction &mf) {
710  if (!EnableLDV)
711    return false;
712  if (!pImpl)
713    pImpl = new LDVImpl(this);
714  return static_cast<LDVImpl*>(pImpl)->runOnMachineFunction(mf);
715}
716
717void LiveDebugVariables::releaseMemory() {
718  if (pImpl)
719    static_cast<LDVImpl*>(pImpl)->clear();
720}
721
722LiveDebugVariables::~LiveDebugVariables() {
723  if (pImpl)
724    delete static_cast<LDVImpl*>(pImpl);
725}
726
727//===----------------------------------------------------------------------===//
728//                           Live Range Splitting
729//===----------------------------------------------------------------------===//
730
731bool
732UserValue::splitLocation(unsigned OldLocNo, ArrayRef<LiveInterval*> NewRegs) {
733  DEBUG({
734    dbgs() << "Splitting Loc" << OldLocNo << '\t';
735    print(dbgs(), 0);
736  });
737  bool DidChange = false;
738  LocMap::iterator LocMapI;
739  LocMapI.setMap(locInts);
740  for (unsigned i = 0; i != NewRegs.size(); ++i) {
741    LiveInterval *LI = NewRegs[i];
742    if (LI->empty())
743      continue;
744
745    // Don't allocate the new LocNo until it is needed.
746    unsigned NewLocNo = ~0u;
747
748    // Iterate over the overlaps between locInts and LI.
749    LocMapI.find(LI->beginIndex());
750    if (!LocMapI.valid())
751      continue;
752    LiveInterval::iterator LII = LI->advanceTo(LI->begin(), LocMapI.start());
753    LiveInterval::iterator LIE = LI->end();
754    while (LocMapI.valid() && LII != LIE) {
755      // At this point, we know that LocMapI.stop() > LII->start.
756      LII = LI->advanceTo(LII, LocMapI.start());
757      if (LII == LIE)
758        break;
759
760      // Now LII->end > LocMapI.start(). Do we have an overlap?
761      if (LocMapI.value() == OldLocNo && LII->start < LocMapI.stop()) {
762        // Overlapping correct location. Allocate NewLocNo now.
763        if (NewLocNo == ~0u) {
764          MachineOperand MO = MachineOperand::CreateReg(LI->reg, false);
765          MO.setSubReg(locations[OldLocNo].getSubReg());
766          NewLocNo = getLocationNo(MO);
767          DidChange = true;
768        }
769
770        SlotIndex LStart = LocMapI.start();
771        SlotIndex LStop  = LocMapI.stop();
772
773        // Trim LocMapI down to the LII overlap.
774        if (LStart < LII->start)
775          LocMapI.setStartUnchecked(LII->start);
776        if (LStop > LII->end)
777          LocMapI.setStopUnchecked(LII->end);
778
779        // Change the value in the overlap. This may trigger coalescing.
780        LocMapI.setValue(NewLocNo);
781
782        // Re-insert any removed OldLocNo ranges.
783        if (LStart < LocMapI.start()) {
784          LocMapI.insert(LStart, LocMapI.start(), OldLocNo);
785          ++LocMapI;
786          assert(LocMapI.valid() && "Unexpected coalescing");
787        }
788        if (LStop > LocMapI.stop()) {
789          ++LocMapI;
790          LocMapI.insert(LII->end, LStop, OldLocNo);
791          --LocMapI;
792        }
793      }
794
795      // Advance to the next overlap.
796      if (LII->end < LocMapI.stop()) {
797        if (++LII == LIE)
798          break;
799        LocMapI.advanceTo(LII->start);
800      } else {
801        ++LocMapI;
802        if (!LocMapI.valid())
803          break;
804        LII = LI->advanceTo(LII, LocMapI.start());
805      }
806    }
807  }
808
809  // Finally, remove any remaining OldLocNo intervals and OldLocNo itself.
810  locations.erase(locations.begin() + OldLocNo);
811  LocMapI.goToBegin();
812  while (LocMapI.valid()) {
813    unsigned v = LocMapI.value();
814    if (v == OldLocNo) {
815      DEBUG(dbgs() << "Erasing [" << LocMapI.start() << ';'
816                   << LocMapI.stop() << ")\n");
817      LocMapI.erase();
818    } else {
819      if (v > OldLocNo)
820        LocMapI.setValueUnchecked(v-1);
821      ++LocMapI;
822    }
823  }
824
825  DEBUG({dbgs() << "Split result: \t"; print(dbgs(), 0);});
826  return DidChange;
827}
828
829bool
830UserValue::splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs) {
831  bool DidChange = false;
832  // Split locations referring to OldReg. Iterate backwards so splitLocation can
833  // safely erase unused locations.
834  for (unsigned i = locations.size(); i ; --i) {
835    unsigned LocNo = i-1;
836    const MachineOperand *Loc = &locations[LocNo];
837    if (!Loc->isReg() || Loc->getReg() != OldReg)
838      continue;
839    DidChange |= splitLocation(LocNo, NewRegs);
840  }
841  return DidChange;
842}
843
844void LDVImpl::splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs) {
845  bool DidChange = false;
846  for (UserValue *UV = lookupVirtReg(OldReg); UV; UV = UV->getNext())
847    DidChange |= UV->splitRegister(OldReg, NewRegs);
848
849  if (!DidChange)
850    return;
851
852  // Map all of the new virtual registers.
853  UserValue *UV = lookupVirtReg(OldReg);
854  for (unsigned i = 0; i != NewRegs.size(); ++i)
855    mapVirtReg(NewRegs[i]->reg, UV);
856}
857
858void LiveDebugVariables::
859splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs) {
860  if (pImpl)
861    static_cast<LDVImpl*>(pImpl)->splitRegister(OldReg, NewRegs);
862}
863
864void
865UserValue::rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI) {
866  // Iterate over locations in reverse makes it easier to handle coalescing.
867  for (unsigned i = locations.size(); i ; --i) {
868    unsigned LocNo = i-1;
869    MachineOperand &Loc = locations[LocNo];
870    // Only virtual registers are rewritten.
871    if (!Loc.isReg() || !Loc.getReg() ||
872        !TargetRegisterInfo::isVirtualRegister(Loc.getReg()))
873      continue;
874    unsigned VirtReg = Loc.getReg();
875    if (VRM.isAssignedReg(VirtReg) &&
876        TargetRegisterInfo::isPhysicalRegister(VRM.getPhys(VirtReg))) {
877      // This can create a %noreg operand in rare cases when the sub-register
878      // index is no longer available. That means the user value is in a
879      // non-existent sub-register, and %noreg is exactly what we want.
880      Loc.substPhysReg(VRM.getPhys(VirtReg), TRI);
881    } else if (VRM.getStackSlot(VirtReg) != VirtRegMap::NO_STACK_SLOT) {
882      // FIXME: Translate SubIdx to a stackslot offset.
883      Loc = MachineOperand::CreateFI(VRM.getStackSlot(VirtReg));
884    } else {
885      Loc.setReg(0);
886      Loc.setSubReg(0);
887    }
888    coalesceLocation(LocNo);
889  }
890}
891
892/// findInsertLocation - Find an iterator for inserting a DBG_VALUE
893/// instruction.
894static MachineBasicBlock::iterator
895findInsertLocation(MachineBasicBlock *MBB, SlotIndex Idx,
896                   LiveIntervals &LIS) {
897  SlotIndex Start = LIS.getMBBStartIdx(MBB);
898  Idx = Idx.getBaseIndex();
899
900  // Try to find an insert location by going backwards from Idx.
901  MachineInstr *MI;
902  while (!(MI = LIS.getInstructionFromIndex(Idx))) {
903    // We've reached the beginning of MBB.
904    if (Idx == Start) {
905      MachineBasicBlock::iterator I = MBB->SkipPHIsAndLabels(MBB->begin());
906      return I;
907    }
908    Idx = Idx.getPrevIndex();
909  }
910
911  // Don't insert anything after the first terminator, though.
912  return MI->isTerminator() ? MBB->getFirstTerminator() :
913                              llvm::next(MachineBasicBlock::iterator(MI));
914}
915
916DebugLoc UserValue::findDebugLoc() {
917  DebugLoc D = dl;
918  dl = DebugLoc();
919  return D;
920}
921void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx,
922                                 unsigned LocNo,
923                                 LiveIntervals &LIS,
924                                 const TargetInstrInfo &TII) {
925  MachineBasicBlock::iterator I = findInsertLocation(MBB, Idx, LIS);
926  MachineOperand &Loc = locations[LocNo];
927  ++NumInsertedDebugValues;
928
929  if (Loc.isReg())
930    BuildMI(*MBB, I, findDebugLoc(), TII.get(TargetOpcode::DBG_VALUE),
931            IsIndirect, Loc.getReg(), offset, variable);
932  else
933    BuildMI(*MBB, I, findDebugLoc(), TII.get(TargetOpcode::DBG_VALUE))
934      .addOperand(Loc).addImm(offset).addMetadata(variable);
935}
936
937void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
938                                const TargetInstrInfo &TII) {
939  MachineFunction::iterator MFEnd = VRM->getMachineFunction().end();
940
941  for (LocMap::const_iterator I = locInts.begin(); I.valid();) {
942    SlotIndex Start = I.start();
943    SlotIndex Stop = I.stop();
944    unsigned LocNo = I.value();
945    DEBUG(dbgs() << "\t[" << Start << ';' << Stop << "):" << LocNo);
946    MachineFunction::iterator MBB = LIS.getMBBFromIndex(Start);
947    SlotIndex MBBEnd = LIS.getMBBEndIdx(MBB);
948
949    DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
950    insertDebugValue(MBB, Start, LocNo, LIS, TII);
951    // This interval may span multiple basic blocks.
952    // Insert a DBG_VALUE into each one.
953    while(Stop > MBBEnd) {
954      // Move to the next block.
955      Start = MBBEnd;
956      if (++MBB == MFEnd)
957        break;
958      MBBEnd = LIS.getMBBEndIdx(MBB);
959      DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
960      insertDebugValue(MBB, Start, LocNo, LIS, TII);
961    }
962    DEBUG(dbgs() << '\n');
963    if (MBB == MFEnd)
964      break;
965
966    ++I;
967  }
968}
969
970void LDVImpl::emitDebugValues(VirtRegMap *VRM) {
971  DEBUG(dbgs() << "********** EMITTING LIVE DEBUG VARIABLES **********\n");
972  const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
973  for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
974    DEBUG(userValues[i]->print(dbgs(), &MF->getTarget()));
975    userValues[i]->rewriteLocations(*VRM, *TRI);
976    userValues[i]->emitDebugValues(VRM, *LIS, *TII);
977  }
978  EmitDone = true;
979}
980
981void LiveDebugVariables::emitDebugValues(VirtRegMap *VRM) {
982  if (pImpl)
983    static_cast<LDVImpl*>(pImpl)->emitDebugValues(VRM);
984}
985
986
987#ifndef NDEBUG
988void LiveDebugVariables::dump() {
989  if (pImpl)
990    static_cast<LDVImpl*>(pImpl)->print(dbgs());
991}
992#endif
993