LiveDebugVariables.cpp revision 818833f27929d650b4323774cd3660860588f687 
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<unsigned> NewRegs,
135                     LiveIntervals &LIS);
136
137public:
138  /// UserValue - Create a new UserValue.
139  UserValue(const MDNode *var, unsigned o, bool i, DebugLoc L,
140            LocMap::Allocator &alloc)
141    : variable(var), offset(o), IsIndirect(i), dl(L), leader(this),
142      next(0), locInts(alloc)
143  {}
144
145  /// getLeader - Get the leader of this value's equivalence class.
146  UserValue *getLeader() {
147    UserValue *l = leader;
148    while (l != l->leader)
149      l = l->leader;
150    return leader = l;
151  }
152
153  /// getNext - Return the next UserValue in the equivalence class.
154  UserValue *getNext() const { return next; }
155
156  /// match - Does this UserValue match the parameters?
157  bool match(const MDNode *Var, unsigned Offset) const {
158    return Var == variable && Offset == offset;
159  }
160
161  /// merge - Merge equivalence classes.
162  static UserValue *merge(UserValue *L1, UserValue *L2) {
163    L2 = L2->getLeader();
164    if (!L1)
165      return L2;
166    L1 = L1->getLeader();
167    if (L1 == L2)
168      return L1;
169    // Splice L2 before L1's members.
170    UserValue *End = L2;
171    while (End->next)
172      End->leader = L1, End = End->next;
173    End->leader = L1;
174    End->next = L1->next;
175    L1->next = L2;
176    return L1;
177  }
178
179  /// getLocationNo - Return the location number that matches Loc.
180  unsigned getLocationNo(const MachineOperand &LocMO) {
181    if (LocMO.isReg()) {
182      if (LocMO.getReg() == 0)
183        return ~0u;
184      // For register locations we dont care about use/def and other flags.
185      for (unsigned i = 0, e = locations.size(); i != e; ++i)
186        if (locations[i].isReg() &&
187            locations[i].getReg() == LocMO.getReg() &&
188            locations[i].getSubReg() == LocMO.getSubReg())
189          return i;
190    } else
191      for (unsigned i = 0, e = locations.size(); i != e; ++i)
192        if (LocMO.isIdenticalTo(locations[i]))
193          return i;
194    locations.push_back(LocMO);
195    // We are storing a MachineOperand outside a MachineInstr.
196    locations.back().clearParent();
197    // Don't store def operands.
198    if (locations.back().isReg())
199      locations.back().setIsUse();
200    return locations.size() - 1;
201  }
202
203  /// mapVirtRegs - Ensure that all virtual register locations are mapped.
204  void mapVirtRegs(LDVImpl *LDV);
205
206  /// addDef - Add a definition point to this value.
207  void addDef(SlotIndex Idx, const MachineOperand &LocMO) {
208    // Add a singular (Idx,Idx) -> Loc mapping.
209    LocMap::iterator I = locInts.find(Idx);
210    if (!I.valid() || I.start() != Idx)
211      I.insert(Idx, Idx.getNextSlot(), getLocationNo(LocMO));
212    else
213      // A later DBG_VALUE at the same SlotIndex overrides the old location.
214      I.setValue(getLocationNo(LocMO));
215  }
216
217  /// extendDef - Extend the current definition as far as possible down the
218  /// dominator tree. Stop when meeting an existing def or when leaving the live
219  /// range of VNI.
220  /// End points where VNI is no longer live are added to Kills.
221  /// @param Idx   Starting point for the definition.
222  /// @param LocNo Location number to propagate.
223  /// @param LI    Restrict liveness to where LI has the value VNI. May be null.
224  /// @param VNI   When LI is not null, this is the value to restrict to.
225  /// @param Kills Append end points of VNI's live range to Kills.
226  /// @param LIS   Live intervals analysis.
227  /// @param MDT   Dominator tree.
228  void extendDef(SlotIndex Idx, unsigned LocNo,
229                 LiveInterval *LI, const VNInfo *VNI,
230                 SmallVectorImpl<SlotIndex> *Kills,
231                 LiveIntervals &LIS, MachineDominatorTree &MDT,
232                 UserValueScopes &UVS);
233
234  /// addDefsFromCopies - The value in LI/LocNo may be copies to other
235  /// registers. Determine if any of the copies are available at the kill
236  /// points, and add defs if possible.
237  /// @param LI      Scan for copies of the value in LI->reg.
238  /// @param LocNo   Location number of LI->reg.
239  /// @param Kills   Points where the range of LocNo could be extended.
240  /// @param NewDefs Append (Idx, LocNo) of inserted defs here.
241  void addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
242                      const SmallVectorImpl<SlotIndex> &Kills,
243                      SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
244                      MachineRegisterInfo &MRI,
245                      LiveIntervals &LIS);
246
247  /// computeIntervals - Compute the live intervals of all locations after
248  /// collecting all their def points.
249  void computeIntervals(MachineRegisterInfo &MRI, const TargetRegisterInfo &TRI,
250                        LiveIntervals &LIS, MachineDominatorTree &MDT,
251                        UserValueScopes &UVS);
252
253  /// splitRegister - Replace OldReg ranges with NewRegs ranges where NewRegs is
254  /// live. Returns true if any changes were made.
255  bool splitRegister(unsigned OldLocNo, ArrayRef<unsigned> NewRegs,
256                     LiveIntervals &LIS);
257
258  /// rewriteLocations - Rewrite virtual register locations according to the
259  /// provided virtual register map.
260  void rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI);
261
262  /// emitDebugValues - Recreate DBG_VALUE instruction from data structures.
263  void emitDebugValues(VirtRegMap *VRM,
264                       LiveIntervals &LIS, const TargetInstrInfo &TRI);
265
266  /// findDebugLoc - Return DebugLoc used for this DBG_VALUE instruction. A
267  /// variable may have more than one corresponding DBG_VALUE instructions.
268  /// Only first one needs DebugLoc to identify variable's lexical scope
269  /// in source file.
270  DebugLoc findDebugLoc();
271
272  /// getDebugLoc - Return DebugLoc of this UserValue.
273  DebugLoc getDebugLoc() { return dl;}
274  void print(raw_ostream&, const TargetMachine*);
275};
276} // namespace
277
278/// LDVImpl - Implementation of the LiveDebugVariables pass.
279namespace {
280class LDVImpl {
281  LiveDebugVariables &pass;
282  LocMap::Allocator allocator;
283  MachineFunction *MF;
284  LiveIntervals *LIS;
285  LexicalScopes LS;
286  MachineDominatorTree *MDT;
287  const TargetRegisterInfo *TRI;
288
289  /// Whether emitDebugValues is called.
290  bool EmitDone;
291  /// Whether the machine function is modified during the pass.
292  bool ModifiedMF;
293
294  /// userValues - All allocated UserValue instances.
295  SmallVector<UserValue*, 8> userValues;
296
297  /// Map virtual register to eq class leader.
298  typedef DenseMap<unsigned, UserValue*> VRMap;
299  VRMap virtRegToEqClass;
300
301  /// Map user variable to eq class leader.
302  typedef DenseMap<const MDNode *, UserValue*> UVMap;
303  UVMap userVarMap;
304
305  /// getUserValue - Find or create a UserValue.
306  UserValue *getUserValue(const MDNode *Var, unsigned Offset,
307                          bool IsIndirect, DebugLoc DL);
308
309  /// lookupVirtReg - Find the EC leader for VirtReg or null.
310  UserValue *lookupVirtReg(unsigned VirtReg);
311
312  /// handleDebugValue - Add DBG_VALUE instruction to our maps.
313  /// @param MI  DBG_VALUE instruction
314  /// @param Idx Last valid SLotIndex before instruction.
315  /// @return    True if the DBG_VALUE instruction should be deleted.
316  bool handleDebugValue(MachineInstr *MI, SlotIndex Idx);
317
318  /// collectDebugValues - Collect and erase all DBG_VALUE instructions, adding
319  /// a UserValue def for each instruction.
320  /// @param mf MachineFunction to be scanned.
321  /// @return True if any debug values were found.
322  bool collectDebugValues(MachineFunction &mf);
323
324  /// computeIntervals - Compute the live intervals of all user values after
325  /// collecting all their def points.
326  void computeIntervals();
327
328public:
329  LDVImpl(LiveDebugVariables *ps) : pass(*ps), EmitDone(false),
330                                    ModifiedMF(false) {}
331  bool runOnMachineFunction(MachineFunction &mf);
332
333  /// clear - Release all memory.
334  void clear() {
335    DeleteContainerPointers(userValues);
336    userValues.clear();
337    virtRegToEqClass.clear();
338    userVarMap.clear();
339    // Make sure we call emitDebugValues if the machine function was modified.
340    assert((!ModifiedMF || EmitDone) &&
341           "Dbg values are not emitted in LDV");
342    EmitDone = false;
343    ModifiedMF = false;
344  }
345
346  /// mapVirtReg - Map virtual register to an equivalence class.
347  void mapVirtReg(unsigned VirtReg, UserValue *EC);
348
349  /// splitRegister -  Replace all references to OldReg with NewRegs.
350  void splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs);
351
352  /// emitDebugValues - Recreate DBG_VALUE instruction from data structures.
353  void emitDebugValues(VirtRegMap *VRM);
354
355  void print(raw_ostream&);
356};
357} // namespace
358
359void UserValue::print(raw_ostream &OS, const TargetMachine *TM) {
360  DIVariable DV(variable);
361  OS << "!\"";
362  DV.printExtendedName(OS);
363  OS << "\"\t";
364  if (offset)
365    OS << '+' << offset;
366  for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) {
367    OS << " [" << I.start() << ';' << I.stop() << "):";
368    if (I.value() == ~0u)
369      OS << "undef";
370    else
371      OS << I.value();
372  }
373  for (unsigned i = 0, e = locations.size(); i != e; ++i) {
374    OS << " Loc" << i << '=';
375    locations[i].print(OS, TM);
376  }
377  OS << '\n';
378}
379
380void LDVImpl::print(raw_ostream &OS) {
381  OS << "********** DEBUG VARIABLES **********\n";
382  for (unsigned i = 0, e = userValues.size(); i != e; ++i)
383    userValues[i]->print(OS, &MF->getTarget());
384}
385
386void UserValue::coalesceLocation(unsigned LocNo) {
387  unsigned KeepLoc = 0;
388  for (unsigned e = locations.size(); KeepLoc != e; ++KeepLoc) {
389    if (KeepLoc == LocNo)
390      continue;
391    if (locations[KeepLoc].isIdenticalTo(locations[LocNo]))
392      break;
393  }
394  // No matches.
395  if (KeepLoc == locations.size())
396    return;
397
398  // Keep the smaller location, erase the larger one.
399  unsigned EraseLoc = LocNo;
400  if (KeepLoc > EraseLoc)
401    std::swap(KeepLoc, EraseLoc);
402  locations.erase(locations.begin() + EraseLoc);
403
404  // Rewrite values.
405  for (LocMap::iterator I = locInts.begin(); I.valid(); ++I) {
406    unsigned v = I.value();
407    if (v == EraseLoc)
408      I.setValue(KeepLoc);      // Coalesce when possible.
409    else if (v > EraseLoc)
410      I.setValueUnchecked(v-1); // Avoid coalescing with untransformed values.
411  }
412}
413
414void UserValue::mapVirtRegs(LDVImpl *LDV) {
415  for (unsigned i = 0, e = locations.size(); i != e; ++i)
416    if (locations[i].isReg() &&
417        TargetRegisterInfo::isVirtualRegister(locations[i].getReg()))
418      LDV->mapVirtReg(locations[i].getReg(), this);
419}
420
421UserValue *LDVImpl::getUserValue(const MDNode *Var, unsigned Offset,
422                                 bool IsIndirect, DebugLoc DL) {
423  UserValue *&Leader = userVarMap[Var];
424  if (Leader) {
425    UserValue *UV = Leader->getLeader();
426    Leader = UV;
427    for (; UV; UV = UV->getNext())
428      if (UV->match(Var, Offset))
429        return UV;
430  }
431
432  UserValue *UV = new UserValue(Var, Offset, IsIndirect, DL, allocator);
433  userValues.push_back(UV);
434  Leader = UserValue::merge(Leader, UV);
435  return UV;
436}
437
438void LDVImpl::mapVirtReg(unsigned VirtReg, UserValue *EC) {
439  assert(TargetRegisterInfo::isVirtualRegister(VirtReg) && "Only map VirtRegs");
440  UserValue *&Leader = virtRegToEqClass[VirtReg];
441  Leader = UserValue::merge(Leader, EC);
442}
443
444UserValue *LDVImpl::lookupVirtReg(unsigned VirtReg) {
445  if (UserValue *UV = virtRegToEqClass.lookup(VirtReg))
446    return UV->getLeader();
447  return 0;
448}
449
450bool LDVImpl::handleDebugValue(MachineInstr *MI, SlotIndex Idx) {
451  // DBG_VALUE loc, offset, variable
452  if (MI->getNumOperands() != 3 ||
453      !(MI->getOperand(1).isReg() || MI->getOperand(1).isImm()) ||
454      !MI->getOperand(2).isMetadata()) {
455    DEBUG(dbgs() << "Can't handle " << *MI);
456    return false;
457  }
458
459  // Get or create the UserValue for (variable,offset).
460  bool IsIndirect = MI->isIndirectDebugValue();
461  unsigned Offset = IsIndirect ? MI->getOperand(1).getImm() : 0;
462  const MDNode *Var = MI->getOperand(2).getMetadata();
463  //here.
464  UserValue *UV = getUserValue(Var, Offset, IsIndirect, MI->getDebugLoc());
465  UV->addDef(Idx, MI->getOperand(0));
466  return true;
467}
468
469bool LDVImpl::collectDebugValues(MachineFunction &mf) {
470  bool Changed = false;
471  for (MachineFunction::iterator MFI = mf.begin(), MFE = mf.end(); MFI != MFE;
472       ++MFI) {
473    MachineBasicBlock *MBB = MFI;
474    for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
475         MBBI != MBBE;) {
476      if (!MBBI->isDebugValue()) {
477        ++MBBI;
478        continue;
479      }
480      // DBG_VALUE has no slot index, use the previous instruction instead.
481      SlotIndex Idx = MBBI == MBB->begin() ?
482        LIS->getMBBStartIdx(MBB) :
483        LIS->getInstructionIndex(llvm::prior(MBBI)).getRegSlot();
484      // Handle consecutive DBG_VALUE instructions with the same slot index.
485      do {
486        if (handleDebugValue(MBBI, Idx)) {
487          MBBI = MBB->erase(MBBI);
488          Changed = true;
489        } else
490          ++MBBI;
491      } while (MBBI != MBBE && MBBI->isDebugValue());
492    }
493  }
494  return Changed;
495}
496
497void UserValue::extendDef(SlotIndex Idx, unsigned LocNo,
498                          LiveInterval *LI, const VNInfo *VNI,
499                          SmallVectorImpl<SlotIndex> *Kills,
500                          LiveIntervals &LIS, MachineDominatorTree &MDT,
501                          UserValueScopes &UVS) {
502  SmallVector<SlotIndex, 16> Todo;
503  Todo.push_back(Idx);
504  do {
505    SlotIndex Start = Todo.pop_back_val();
506    MachineBasicBlock *MBB = LIS.getMBBFromIndex(Start);
507    SlotIndex Stop = LIS.getMBBEndIdx(MBB);
508    LocMap::iterator I = locInts.find(Start);
509
510    // Limit to VNI's live range.
511    bool ToEnd = true;
512    if (LI && VNI) {
513      LiveRange *Range = LI->getLiveRangeContaining(Start);
514      if (!Range || Range->valno != VNI) {
515        if (Kills)
516          Kills->push_back(Start);
517        continue;
518      }
519      if (Range->end < Stop)
520        Stop = Range->end, ToEnd = false;
521    }
522
523    // There could already be a short def at Start.
524    if (I.valid() && I.start() <= Start) {
525      // Stop when meeting a different location or an already extended interval.
526      Start = Start.getNextSlot();
527      if (I.value() != LocNo || I.stop() != Start)
528        continue;
529      // This is a one-slot placeholder. Just skip it.
530      ++I;
531    }
532
533    // Limited by the next def.
534    if (I.valid() && I.start() < Stop)
535      Stop = I.start(), ToEnd = false;
536    // Limited by VNI's live range.
537    else if (!ToEnd && Kills)
538      Kills->push_back(Stop);
539
540    if (Start >= Stop)
541      continue;
542
543    I.insert(Start, Stop, LocNo);
544
545    // If we extended to the MBB end, propagate down the dominator tree.
546    if (!ToEnd)
547      continue;
548    const std::vector<MachineDomTreeNode*> &Children =
549      MDT.getNode(MBB)->getChildren();
550    for (unsigned i = 0, e = Children.size(); i != e; ++i) {
551      MachineBasicBlock *MBB = Children[i]->getBlock();
552      if (UVS.dominates(MBB))
553        Todo.push_back(LIS.getMBBStartIdx(MBB));
554    }
555  } while (!Todo.empty());
556}
557
558void
559UserValue::addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
560                      const SmallVectorImpl<SlotIndex> &Kills,
561                      SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
562                      MachineRegisterInfo &MRI, LiveIntervals &LIS) {
563  if (Kills.empty())
564    return;
565  // Don't track copies from physregs, there are too many uses.
566  if (!TargetRegisterInfo::isVirtualRegister(LI->reg))
567    return;
568
569  // Collect all the (vreg, valno) pairs that are copies of LI.
570  SmallVector<std::pair<LiveInterval*, const VNInfo*>, 8> CopyValues;
571  for (MachineRegisterInfo::use_nodbg_iterator
572         UI = MRI.use_nodbg_begin(LI->reg),
573         UE = MRI.use_nodbg_end(); UI != UE; ++UI) {
574    // Copies of the full value.
575    if (UI.getOperand().getSubReg() || !UI->isCopy())
576      continue;
577    MachineInstr *MI = &*UI;
578    unsigned DstReg = MI->getOperand(0).getReg();
579
580    // Don't follow copies to physregs. These are usually setting up call
581    // arguments, and the argument registers are always call clobbered. We are
582    // better off in the source register which could be a callee-saved register,
583    // or it could be spilled.
584    if (!TargetRegisterInfo::isVirtualRegister(DstReg))
585      continue;
586
587    // Is LocNo extended to reach this copy? If not, another def may be blocking
588    // it, or we are looking at a wrong value of LI.
589    SlotIndex Idx = LIS.getInstructionIndex(MI);
590    LocMap::iterator I = locInts.find(Idx.getRegSlot(true));
591    if (!I.valid() || I.value() != LocNo)
592      continue;
593
594    if (!LIS.hasInterval(DstReg))
595      continue;
596    LiveInterval *DstLI = &LIS.getInterval(DstReg);
597    const VNInfo *DstVNI = DstLI->getVNInfoAt(Idx.getRegSlot());
598    assert(DstVNI && DstVNI->def == Idx.getRegSlot() && "Bad copy value");
599    CopyValues.push_back(std::make_pair(DstLI, DstVNI));
600  }
601
602  if (CopyValues.empty())
603    return;
604
605  DEBUG(dbgs() << "Got " << CopyValues.size() << " copies of " << *LI << '\n');
606
607  // Try to add defs of the copied values for each kill point.
608  for (unsigned i = 0, e = Kills.size(); i != e; ++i) {
609    SlotIndex Idx = Kills[i];
610    for (unsigned j = 0, e = CopyValues.size(); j != e; ++j) {
611      LiveInterval *DstLI = CopyValues[j].first;
612      const VNInfo *DstVNI = CopyValues[j].second;
613      if (DstLI->getVNInfoAt(Idx) != DstVNI)
614        continue;
615      // Check that there isn't already a def at Idx
616      LocMap::iterator I = locInts.find(Idx);
617      if (I.valid() && I.start() <= Idx)
618        continue;
619      DEBUG(dbgs() << "Kill at " << Idx << " covered by valno #"
620                   << DstVNI->id << " in " << *DstLI << '\n');
621      MachineInstr *CopyMI = LIS.getInstructionFromIndex(DstVNI->def);
622      assert(CopyMI && CopyMI->isCopy() && "Bad copy value");
623      unsigned LocNo = getLocationNo(CopyMI->getOperand(0));
624      I.insert(Idx, Idx.getNextSlot(), LocNo);
625      NewDefs.push_back(std::make_pair(Idx, LocNo));
626      break;
627    }
628  }
629}
630
631void
632UserValue::computeIntervals(MachineRegisterInfo &MRI,
633                            const TargetRegisterInfo &TRI,
634                            LiveIntervals &LIS,
635                            MachineDominatorTree &MDT,
636                            UserValueScopes &UVS) {
637  SmallVector<std::pair<SlotIndex, unsigned>, 16> Defs;
638
639  // Collect all defs to be extended (Skipping undefs).
640  for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I)
641    if (I.value() != ~0u)
642      Defs.push_back(std::make_pair(I.start(), I.value()));
643
644  // Extend all defs, and possibly add new ones along the way.
645  for (unsigned i = 0; i != Defs.size(); ++i) {
646    SlotIndex Idx = Defs[i].first;
647    unsigned LocNo = Defs[i].second;
648    const MachineOperand &Loc = locations[LocNo];
649
650    if (!Loc.isReg()) {
651      extendDef(Idx, LocNo, 0, 0, 0, LIS, MDT, UVS);
652      continue;
653    }
654
655    // Register locations are constrained to where the register value is live.
656    if (TargetRegisterInfo::isVirtualRegister(Loc.getReg())) {
657      LiveInterval *LI = 0;
658      const VNInfo *VNI = 0;
659      if (LIS.hasInterval(Loc.getReg())) {
660        LI = &LIS.getInterval(Loc.getReg());
661        VNI = LI->getVNInfoAt(Idx);
662      }
663      SmallVector<SlotIndex, 16> Kills;
664      extendDef(Idx, LocNo, LI, VNI, &Kills, LIS, MDT, UVS);
665      if (LI)
666        addDefsFromCopies(LI, LocNo, Kills, Defs, MRI, LIS);
667      continue;
668    }
669
670    // For physregs, use the live range of the first regunit as a guide.
671    unsigned Unit = *MCRegUnitIterator(Loc.getReg(), &TRI);
672    LiveInterval *LI = &LIS.getRegUnit(Unit);
673    const VNInfo *VNI = LI->getVNInfoAt(Idx);
674    // Don't track copies from physregs, it is too expensive.
675    extendDef(Idx, LocNo, LI, VNI, 0, LIS, MDT, UVS);
676  }
677
678  // Finally, erase all the undefs.
679  for (LocMap::iterator I = locInts.begin(); I.valid();)
680    if (I.value() == ~0u)
681      I.erase();
682    else
683      ++I;
684}
685
686void LDVImpl::computeIntervals() {
687  for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
688    UserValueScopes UVS(userValues[i]->getDebugLoc(), LS);
689    userValues[i]->computeIntervals(MF->getRegInfo(), *TRI, *LIS, *MDT, UVS);
690    userValues[i]->mapVirtRegs(this);
691  }
692}
693
694bool LDVImpl::runOnMachineFunction(MachineFunction &mf) {
695  MF = &mf;
696  LIS = &pass.getAnalysis<LiveIntervals>();
697  MDT = &pass.getAnalysis<MachineDominatorTree>();
698  TRI = mf.getTarget().getRegisterInfo();
699  clear();
700  LS.initialize(mf);
701  DEBUG(dbgs() << "********** COMPUTING LIVE DEBUG VARIABLES: "
702               << mf.getName() << " **********\n");
703
704  bool Changed = collectDebugValues(mf);
705  computeIntervals();
706  DEBUG(print(dbgs()));
707  LS.releaseMemory();
708  ModifiedMF = Changed;
709  return Changed;
710}
711
712bool LiveDebugVariables::runOnMachineFunction(MachineFunction &mf) {
713  if (!EnableLDV)
714    return false;
715  if (!pImpl)
716    pImpl = new LDVImpl(this);
717  return static_cast<LDVImpl*>(pImpl)->runOnMachineFunction(mf);
718}
719
720void LiveDebugVariables::releaseMemory() {
721  if (pImpl)
722    static_cast<LDVImpl*>(pImpl)->clear();
723}
724
725LiveDebugVariables::~LiveDebugVariables() {
726  if (pImpl)
727    delete static_cast<LDVImpl*>(pImpl);
728}
729
730//===----------------------------------------------------------------------===//
731//                           Live Range Splitting
732//===----------------------------------------------------------------------===//
733
734bool
735UserValue::splitLocation(unsigned OldLocNo, ArrayRef<unsigned> NewRegs,
736                         LiveIntervals& LIS) {
737  DEBUG({
738    dbgs() << "Splitting Loc" << OldLocNo << '\t';
739    print(dbgs(), 0);
740  });
741  bool DidChange = false;
742  LocMap::iterator LocMapI;
743  LocMapI.setMap(locInts);
744  for (unsigned i = 0; i != NewRegs.size(); ++i) {
745    LiveInterval *LI = &LIS.getInterval(NewRegs[i]);
746    if (LI->empty())
747      continue;
748
749    // Don't allocate the new LocNo until it is needed.
750    unsigned NewLocNo = ~0u;
751
752    // Iterate over the overlaps between locInts and LI.
753    LocMapI.find(LI->beginIndex());
754    if (!LocMapI.valid())
755      continue;
756    LiveInterval::iterator LII = LI->advanceTo(LI->begin(), LocMapI.start());
757    LiveInterval::iterator LIE = LI->end();
758    while (LocMapI.valid() && LII != LIE) {
759      // At this point, we know that LocMapI.stop() > LII->start.
760      LII = LI->advanceTo(LII, LocMapI.start());
761      if (LII == LIE)
762        break;
763
764      // Now LII->end > LocMapI.start(). Do we have an overlap?
765      if (LocMapI.value() == OldLocNo && LII->start < LocMapI.stop()) {
766        // Overlapping correct location. Allocate NewLocNo now.
767        if (NewLocNo == ~0u) {
768          MachineOperand MO = MachineOperand::CreateReg(LI->reg, false);
769          MO.setSubReg(locations[OldLocNo].getSubReg());
770          NewLocNo = getLocationNo(MO);
771          DidChange = true;
772        }
773
774        SlotIndex LStart = LocMapI.start();
775        SlotIndex LStop  = LocMapI.stop();
776
777        // Trim LocMapI down to the LII overlap.
778        if (LStart < LII->start)
779          LocMapI.setStartUnchecked(LII->start);
780        if (LStop > LII->end)
781          LocMapI.setStopUnchecked(LII->end);
782
783        // Change the value in the overlap. This may trigger coalescing.
784        LocMapI.setValue(NewLocNo);
785
786        // Re-insert any removed OldLocNo ranges.
787        if (LStart < LocMapI.start()) {
788          LocMapI.insert(LStart, LocMapI.start(), OldLocNo);
789          ++LocMapI;
790          assert(LocMapI.valid() && "Unexpected coalescing");
791        }
792        if (LStop > LocMapI.stop()) {
793          ++LocMapI;
794          LocMapI.insert(LII->end, LStop, OldLocNo);
795          --LocMapI;
796        }
797      }
798
799      // Advance to the next overlap.
800      if (LII->end < LocMapI.stop()) {
801        if (++LII == LIE)
802          break;
803        LocMapI.advanceTo(LII->start);
804      } else {
805        ++LocMapI;
806        if (!LocMapI.valid())
807          break;
808        LII = LI->advanceTo(LII, LocMapI.start());
809      }
810    }
811  }
812
813  // Finally, remove any remaining OldLocNo intervals and OldLocNo itself.
814  locations.erase(locations.begin() + OldLocNo);
815  LocMapI.goToBegin();
816  while (LocMapI.valid()) {
817    unsigned v = LocMapI.value();
818    if (v == OldLocNo) {
819      DEBUG(dbgs() << "Erasing [" << LocMapI.start() << ';'
820                   << LocMapI.stop() << ")\n");
821      LocMapI.erase();
822    } else {
823      if (v > OldLocNo)
824        LocMapI.setValueUnchecked(v-1);
825      ++LocMapI;
826    }
827  }
828
829  DEBUG({dbgs() << "Split result: \t"; print(dbgs(), 0);});
830  return DidChange;
831}
832
833bool
834UserValue::splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs,
835                         LiveIntervals &LIS) {
836  bool DidChange = false;
837  // Split locations referring to OldReg. Iterate backwards so splitLocation can
838  // safely erase unused locations.
839  for (unsigned i = locations.size(); i ; --i) {
840    unsigned LocNo = i-1;
841    const MachineOperand *Loc = &locations[LocNo];
842    if (!Loc->isReg() || Loc->getReg() != OldReg)
843      continue;
844    DidChange |= splitLocation(LocNo, NewRegs, LIS);
845  }
846  return DidChange;
847}
848
849void LDVImpl::splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs) {
850  bool DidChange = false;
851  for (UserValue *UV = lookupVirtReg(OldReg); UV; UV = UV->getNext())
852    DidChange |= UV->splitRegister(OldReg, NewRegs, *LIS);
853
854  if (!DidChange)
855    return;
856
857  // Map all of the new virtual registers.
858  UserValue *UV = lookupVirtReg(OldReg);
859  for (unsigned i = 0; i != NewRegs.size(); ++i)
860    mapVirtReg(NewRegs[i], UV);
861}
862
863void LiveDebugVariables::
864splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs, LiveIntervals &LIS) {
865  if (pImpl)
866    static_cast<LDVImpl*>(pImpl)->splitRegister(OldReg, NewRegs);
867}
868
869void
870UserValue::rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI) {
871  // Iterate over locations in reverse makes it easier to handle coalescing.
872  for (unsigned i = locations.size(); i ; --i) {
873    unsigned LocNo = i-1;
874    MachineOperand &Loc = locations[LocNo];
875    // Only virtual registers are rewritten.
876    if (!Loc.isReg() || !Loc.getReg() ||
877        !TargetRegisterInfo::isVirtualRegister(Loc.getReg()))
878      continue;
879    unsigned VirtReg = Loc.getReg();
880    if (VRM.isAssignedReg(VirtReg) &&
881        TargetRegisterInfo::isPhysicalRegister(VRM.getPhys(VirtReg))) {
882      // This can create a %noreg operand in rare cases when the sub-register
883      // index is no longer available. That means the user value is in a
884      // non-existent sub-register, and %noreg is exactly what we want.
885      Loc.substPhysReg(VRM.getPhys(VirtReg), TRI);
886    } else if (VRM.getStackSlot(VirtReg) != VirtRegMap::NO_STACK_SLOT) {
887      // FIXME: Translate SubIdx to a stackslot offset.
888      Loc = MachineOperand::CreateFI(VRM.getStackSlot(VirtReg));
889    } else {
890      Loc.setReg(0);
891      Loc.setSubReg(0);
892    }
893    coalesceLocation(LocNo);
894  }
895}
896
897/// findInsertLocation - Find an iterator for inserting a DBG_VALUE
898/// instruction.
899static MachineBasicBlock::iterator
900findInsertLocation(MachineBasicBlock *MBB, SlotIndex Idx,
901                   LiveIntervals &LIS) {
902  SlotIndex Start = LIS.getMBBStartIdx(MBB);
903  Idx = Idx.getBaseIndex();
904
905  // Try to find an insert location by going backwards from Idx.
906  MachineInstr *MI;
907  while (!(MI = LIS.getInstructionFromIndex(Idx))) {
908    // We've reached the beginning of MBB.
909    if (Idx == Start) {
910      MachineBasicBlock::iterator I = MBB->SkipPHIsAndLabels(MBB->begin());
911      return I;
912    }
913    Idx = Idx.getPrevIndex();
914  }
915
916  // Don't insert anything after the first terminator, though.
917  return MI->isTerminator() ? MBB->getFirstTerminator() :
918                              llvm::next(MachineBasicBlock::iterator(MI));
919}
920
921DebugLoc UserValue::findDebugLoc() {
922  DebugLoc D = dl;
923  dl = DebugLoc();
924  return D;
925}
926void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx,
927                                 unsigned LocNo,
928                                 LiveIntervals &LIS,
929                                 const TargetInstrInfo &TII) {
930  MachineBasicBlock::iterator I = findInsertLocation(MBB, Idx, LIS);
931  MachineOperand &Loc = locations[LocNo];
932  ++NumInsertedDebugValues;
933
934  if (Loc.isReg())
935    BuildMI(*MBB, I, findDebugLoc(), TII.get(TargetOpcode::DBG_VALUE),
936            IsIndirect, Loc.getReg(), offset, variable);
937  else
938    BuildMI(*MBB, I, findDebugLoc(), TII.get(TargetOpcode::DBG_VALUE))
939      .addOperand(Loc).addImm(offset).addMetadata(variable);
940}
941
942void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
943                                const TargetInstrInfo &TII) {
944  MachineFunction::iterator MFEnd = VRM->getMachineFunction().end();
945
946  for (LocMap::const_iterator I = locInts.begin(); I.valid();) {
947    SlotIndex Start = I.start();
948    SlotIndex Stop = I.stop();
949    unsigned LocNo = I.value();
950    DEBUG(dbgs() << "\t[" << Start << ';' << Stop << "):" << LocNo);
951    MachineFunction::iterator MBB = LIS.getMBBFromIndex(Start);
952    SlotIndex MBBEnd = LIS.getMBBEndIdx(MBB);
953
954    DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
955    insertDebugValue(MBB, Start, LocNo, LIS, TII);
956    // This interval may span multiple basic blocks.
957    // Insert a DBG_VALUE into each one.
958    while(Stop > MBBEnd) {
959      // Move to the next block.
960      Start = MBBEnd;
961      if (++MBB == MFEnd)
962        break;
963      MBBEnd = LIS.getMBBEndIdx(MBB);
964      DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
965      insertDebugValue(MBB, Start, LocNo, LIS, TII);
966    }
967    DEBUG(dbgs() << '\n');
968    if (MBB == MFEnd)
969      break;
970
971    ++I;
972  }
973}
974
975void LDVImpl::emitDebugValues(VirtRegMap *VRM) {
976  DEBUG(dbgs() << "********** EMITTING LIVE DEBUG VARIABLES **********\n");
977  const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
978  for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
979    DEBUG(userValues[i]->print(dbgs(), &MF->getTarget()));
980    userValues[i]->rewriteLocations(*VRM, *TRI);
981    userValues[i]->emitDebugValues(VRM, *LIS, *TII);
982  }
983  EmitDone = true;
984}
985
986void LiveDebugVariables::emitDebugValues(VirtRegMap *VRM) {
987  if (pImpl)
988    static_cast<LDVImpl*>(pImpl)->emitDebugValues(VRM);
989}
990
991
992#ifndef NDEBUG
993void LiveDebugVariables::dump() {
994  if (pImpl)
995    static_cast<LDVImpl*>(pImpl)->print(dbgs());
996}
997#endif
998