1 //===- LiveDebugVariables.cpp - Tracking debug info variables -------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the LiveDebugVariables analysis.
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.
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.
20 //===----------------------------------------------------------------------===//
22 #include "LiveDebugVariables.h"
23 #include "llvm/ADT/IntervalMap.h"
24 #include "llvm/ADT/Statistic.h"
25 #include "llvm/CodeGen/LexicalScopes.h"
26 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
27 #include "llvm/CodeGen/MachineDominators.h"
28 #include "llvm/CodeGen/MachineFunction.h"
29 #include "llvm/CodeGen/MachineInstrBuilder.h"
30 #include "llvm/CodeGen/MachineRegisterInfo.h"
31 #include "llvm/CodeGen/Passes.h"
32 #include "llvm/CodeGen/VirtRegMap.h"
33 #include "llvm/IR/Constants.h"
34 #include "llvm/IR/DebugInfo.h"
35 #include "llvm/IR/Metadata.h"
36 #include "llvm/IR/Value.h"
37 #include "llvm/Support/CommandLine.h"
38 #include "llvm/Support/Debug.h"
39 #include "llvm/Support/raw_ostream.h"
40 #include "llvm/Target/TargetInstrInfo.h"
41 #include "llvm/Target/TargetMachine.h"
42 #include "llvm/Target/TargetRegisterInfo.h"
43 #include "llvm/Target/TargetSubtargetInfo.h"
48 #define DEBUG_TYPE "livedebug"
51 EnableLDV("live-debug-variables", cl::init(true),
52 cl::desc("Enable the live debug variables pass"), cl::Hidden);
54 STATISTIC(NumInsertedDebugValues, "Number of DBG_VALUEs inserted");
55 char LiveDebugVariables::ID = 0;
57 INITIALIZE_PASS_BEGIN(LiveDebugVariables, "livedebugvars",
58 "Debug Variable Analysis", false, false)
59 INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
60 INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
61 INITIALIZE_PASS_END(LiveDebugVariables, "livedebugvars",
62 "Debug Variable Analysis", false, false)
64 void LiveDebugVariables::getAnalysisUsage(AnalysisUsage &AU) const {
65 AU.addRequired<MachineDominatorTree>();
66 AU.addRequiredTransitive<LiveIntervals>();
68 MachineFunctionPass::getAnalysisUsage(AU);
71 LiveDebugVariables::LiveDebugVariables() : MachineFunctionPass(ID), pImpl(nullptr) {
72 initializeLiveDebugVariablesPass(*PassRegistry::getPassRegistry());
75 /// LocMap - Map of where a user value is live, and its location.
76 typedef IntervalMap<SlotIndex, unsigned, 4> LocMap;
79 /// UserValueScopes - Keeps track of lexical scopes associated with a
80 /// user value's source location.
81 class UserValueScopes {
84 SmallPtrSet<const MachineBasicBlock *, 4> LBlocks;
87 UserValueScopes(DebugLoc D, LexicalScopes &L) : DL(D), LS(L) {}
89 /// dominates - Return true if current scope dominates at least one machine
90 /// instruction in a given machine basic block.
91 bool dominates(MachineBasicBlock *MBB) {
93 LS.getMachineBasicBlocks(DL, LBlocks);
94 return LBlocks.count(MBB) != 0 || LS.dominates(DL, MBB);
97 } // end anonymous namespace
99 /// UserValue - A user value is a part of a debug info user variable.
101 /// A DBG_VALUE instruction notes that (a sub-register of) a virtual register
102 /// holds part of a user variable. The part is identified by a byte offset.
104 /// UserValues are grouped into equivalence classes for easier searching. Two
105 /// user values are related if they refer to the same variable, or if they are
106 /// held by the same virtual register. The equivalence class is the transitive
107 /// closure of that relation.
111 const MDNode *Variable; ///< The debug info variable we are part of.
112 const MDNode *Expression; ///< Any complex address expression.
113 unsigned offset; ///< Byte offset into variable.
114 bool IsIndirect; ///< true if this is a register-indirect+offset value.
115 DebugLoc dl; ///< The debug location for the variable. This is
116 ///< used by dwarf writer to find lexical scope.
117 UserValue *leader; ///< Equivalence class leader.
118 UserValue *next; ///< Next value in equivalence class, or null.
120 /// Numbered locations referenced by locmap.
121 SmallVector<MachineOperand, 4> locations;
123 /// Map of slot indices where this value is live.
126 /// coalesceLocation - After LocNo was changed, check if it has become
127 /// identical to another location, and coalesce them. This may cause LocNo or
128 /// a later location to be erased, but no earlier location will be erased.
129 void coalesceLocation(unsigned LocNo);
131 /// insertDebugValue - Insert a DBG_VALUE into MBB at Idx for LocNo.
132 void insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx, unsigned LocNo,
133 LiveIntervals &LIS, const TargetInstrInfo &TII);
135 /// splitLocation - Replace OldLocNo ranges with NewRegs ranges where NewRegs
136 /// is live. Returns true if any changes were made.
137 bool splitLocation(unsigned OldLocNo, ArrayRef<unsigned> NewRegs,
141 /// UserValue - Create a new UserValue.
142 UserValue(const MDNode *var, const MDNode *expr, unsigned o, bool i,
143 DebugLoc L, LocMap::Allocator &alloc)
144 : Variable(var), Expression(expr), offset(o), IsIndirect(i), dl(L),
145 leader(this), next(nullptr), locInts(alloc) {}
147 /// getLeader - Get the leader of this value's equivalence class.
148 UserValue *getLeader() {
149 UserValue *l = leader;
150 while (l != l->leader)
155 /// getNext - Return the next UserValue in the equivalence class.
156 UserValue *getNext() const { return next; }
158 /// match - Does this UserValue match the parameters?
159 bool match(const MDNode *Var, const MDNode *Expr, const DILocation *IA,
160 unsigned Offset, bool indirect) const {
161 return Var == Variable && Expr == Expression && dl->getInlinedAt() == IA &&
162 Offset == offset && indirect == IsIndirect;
165 /// merge - Merge equivalence classes.
166 static UserValue *merge(UserValue *L1, UserValue *L2) {
167 L2 = L2->getLeader();
170 L1 = L1->getLeader();
173 // Splice L2 before L1's members.
176 End->leader = L1, End = End->next;
178 End->next = L1->next;
183 /// getLocationNo - Return the location number that matches Loc.
184 unsigned getLocationNo(const MachineOperand &LocMO) {
186 if (LocMO.getReg() == 0)
188 // For register locations we dont care about use/def and other flags.
189 for (unsigned i = 0, e = locations.size(); i != e; ++i)
190 if (locations[i].isReg() &&
191 locations[i].getReg() == LocMO.getReg() &&
192 locations[i].getSubReg() == LocMO.getSubReg())
195 for (unsigned i = 0, e = locations.size(); i != e; ++i)
196 if (LocMO.isIdenticalTo(locations[i]))
198 locations.push_back(LocMO);
199 // We are storing a MachineOperand outside a MachineInstr.
200 locations.back().clearParent();
201 // Don't store def operands.
202 if (locations.back().isReg())
203 locations.back().setIsUse();
204 return locations.size() - 1;
207 /// mapVirtRegs - Ensure that all virtual register locations are mapped.
208 void mapVirtRegs(LDVImpl *LDV);
210 /// addDef - Add a definition point to this value.
211 void addDef(SlotIndex Idx, const MachineOperand &LocMO) {
212 // Add a singular (Idx,Idx) -> Loc mapping.
213 LocMap::iterator I = locInts.find(Idx);
214 if (!I.valid() || I.start() != Idx)
215 I.insert(Idx, Idx.getNextSlot(), getLocationNo(LocMO));
217 // A later DBG_VALUE at the same SlotIndex overrides the old location.
218 I.setValue(getLocationNo(LocMO));
221 /// extendDef - Extend the current definition as far as possible down the
222 /// dominator tree. Stop when meeting an existing def or when leaving the live
224 /// End points where VNI is no longer live are added to Kills.
225 /// @param Idx Starting point for the definition.
226 /// @param LocNo Location number to propagate.
227 /// @param LR Restrict liveness to where LR has the value VNI. May be null.
228 /// @param VNI When LR is not null, this is the value to restrict to.
229 /// @param Kills Append end points of VNI's live range to Kills.
230 /// @param LIS Live intervals analysis.
231 /// @param MDT Dominator tree.
232 void extendDef(SlotIndex Idx, unsigned LocNo,
233 LiveRange *LR, const VNInfo *VNI,
234 SmallVectorImpl<SlotIndex> *Kills,
235 LiveIntervals &LIS, MachineDominatorTree &MDT,
236 UserValueScopes &UVS);
238 /// addDefsFromCopies - The value in LI/LocNo may be copies to other
239 /// registers. Determine if any of the copies are available at the kill
240 /// points, and add defs if possible.
241 /// @param LI Scan for copies of the value in LI->reg.
242 /// @param LocNo Location number of LI->reg.
243 /// @param Kills Points where the range of LocNo could be extended.
244 /// @param NewDefs Append (Idx, LocNo) of inserted defs here.
245 void addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
246 const SmallVectorImpl<SlotIndex> &Kills,
247 SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
248 MachineRegisterInfo &MRI,
251 /// computeIntervals - Compute the live intervals of all locations after
252 /// collecting all their def points.
253 void computeIntervals(MachineRegisterInfo &MRI, const TargetRegisterInfo &TRI,
254 LiveIntervals &LIS, MachineDominatorTree &MDT,
255 UserValueScopes &UVS);
257 /// splitRegister - Replace OldReg ranges with NewRegs ranges where NewRegs is
258 /// live. Returns true if any changes were made.
259 bool splitRegister(unsigned OldLocNo, ArrayRef<unsigned> NewRegs,
262 /// rewriteLocations - Rewrite virtual register locations according to the
263 /// provided virtual register map.
264 void rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI);
266 /// emitDebugValues - Recreate DBG_VALUE instruction from data structures.
267 void emitDebugValues(VirtRegMap *VRM,
268 LiveIntervals &LIS, const TargetInstrInfo &TRI);
270 /// getDebugLoc - Return DebugLoc of this UserValue.
271 DebugLoc getDebugLoc() { return dl;}
272 void print(raw_ostream &, const TargetRegisterInfo *);
276 /// LDVImpl - Implementation of the LiveDebugVariables pass.
279 LiveDebugVariables &pass;
280 LocMap::Allocator allocator;
284 MachineDominatorTree *MDT;
285 const TargetRegisterInfo *TRI;
287 /// Whether emitDebugValues is called.
289 /// Whether the machine function is modified during the pass.
292 /// userValues - All allocated UserValue instances.
293 SmallVector<std::unique_ptr<UserValue>, 8> userValues;
295 /// Map virtual register to eq class leader.
296 typedef DenseMap<unsigned, UserValue*> VRMap;
297 VRMap virtRegToEqClass;
299 /// Map user variable to eq class leader.
300 typedef DenseMap<const MDNode *, UserValue*> UVMap;
303 /// getUserValue - Find or create a UserValue.
304 UserValue *getUserValue(const MDNode *Var, const MDNode *Expr,
305 unsigned Offset, bool IsIndirect, DebugLoc DL);
307 /// lookupVirtReg - Find the EC leader for VirtReg or null.
308 UserValue *lookupVirtReg(unsigned VirtReg);
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);
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);
322 /// computeIntervals - Compute the live intervals of all user values after
323 /// collecting all their def points.
324 void computeIntervals();
327 LDVImpl(LiveDebugVariables *ps)
328 : pass(*ps), MF(nullptr), EmitDone(false), ModifiedMF(false) {}
329 bool runOnMachineFunction(MachineFunction &mf);
331 /// clear - Release all memory.
335 virtRegToEqClass.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");
345 /// mapVirtReg - Map virtual register to an equivalence class.
346 void mapVirtReg(unsigned VirtReg, UserValue *EC);
348 /// splitRegister - Replace all references to OldReg with NewRegs.
349 void splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs);
351 /// emitDebugValues - Recreate DBG_VALUE instruction from data structures.
352 void emitDebugValues(VirtRegMap *VRM);
354 void print(raw_ostream&);
358 static void printDebugLoc(DebugLoc DL, raw_ostream &CommentOS,
359 const LLVMContext &Ctx) {
363 auto *Scope = cast<DIScope>(DL.getScope());
364 // Omit the directory, because it's likely to be long and uninteresting.
365 CommentOS << Scope->getFilename();
366 CommentOS << ':' << DL.getLine();
367 if (DL.getCol() != 0)
368 CommentOS << ':' << DL.getCol();
370 DebugLoc InlinedAtDL = DL.getInlinedAt();
375 printDebugLoc(InlinedAtDL, CommentOS, Ctx);
379 static void printExtendedName(raw_ostream &OS, const DILocalVariable *V,
380 const DILocation *DL) {
381 const LLVMContext &Ctx = V->getContext();
382 StringRef Res = V->getName();
384 OS << Res << "," << V->getLine();
385 if (auto *InlinedAt = DL->getInlinedAt()) {
386 if (DebugLoc InlinedAtDL = InlinedAt) {
388 printDebugLoc(InlinedAtDL, OS, Ctx);
394 void UserValue::print(raw_ostream &OS, const TargetRegisterInfo *TRI) {
395 auto *DV = cast<DILocalVariable>(Variable);
397 printExtendedName(OS, DV, dl);
402 for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) {
403 OS << " [" << I.start() << ';' << I.stop() << "):";
404 if (I.value() == ~0u)
409 for (unsigned i = 0, e = locations.size(); i != e; ++i) {
410 OS << " Loc" << i << '=';
411 locations[i].print(OS, TRI);
416 void LDVImpl::print(raw_ostream &OS) {
417 OS << "********** DEBUG VARIABLES **********\n";
418 for (unsigned i = 0, e = userValues.size(); i != e; ++i)
419 userValues[i]->print(OS, TRI);
422 void UserValue::coalesceLocation(unsigned LocNo) {
423 unsigned KeepLoc = 0;
424 for (unsigned e = locations.size(); KeepLoc != e; ++KeepLoc) {
425 if (KeepLoc == LocNo)
427 if (locations[KeepLoc].isIdenticalTo(locations[LocNo]))
431 if (KeepLoc == locations.size())
434 // Keep the smaller location, erase the larger one.
435 unsigned EraseLoc = LocNo;
436 if (KeepLoc > EraseLoc)
437 std::swap(KeepLoc, EraseLoc);
438 locations.erase(locations.begin() + EraseLoc);
441 for (LocMap::iterator I = locInts.begin(); I.valid(); ++I) {
442 unsigned v = I.value();
444 I.setValue(KeepLoc); // Coalesce when possible.
445 else if (v > EraseLoc)
446 I.setValueUnchecked(v-1); // Avoid coalescing with untransformed values.
450 void UserValue::mapVirtRegs(LDVImpl *LDV) {
451 for (unsigned i = 0, e = locations.size(); i != e; ++i)
452 if (locations[i].isReg() &&
453 TargetRegisterInfo::isVirtualRegister(locations[i].getReg()))
454 LDV->mapVirtReg(locations[i].getReg(), this);
457 UserValue *LDVImpl::getUserValue(const MDNode *Var, const MDNode *Expr,
458 unsigned Offset, bool IsIndirect,
460 UserValue *&Leader = userVarMap[Var];
462 UserValue *UV = Leader->getLeader();
464 for (; UV; UV = UV->getNext())
465 if (UV->match(Var, Expr, DL->getInlinedAt(), Offset, IsIndirect))
469 userValues.push_back(
470 make_unique<UserValue>(Var, Expr, Offset, IsIndirect, DL, allocator));
471 UserValue *UV = userValues.back().get();
472 Leader = UserValue::merge(Leader, UV);
476 void LDVImpl::mapVirtReg(unsigned VirtReg, UserValue *EC) {
477 assert(TargetRegisterInfo::isVirtualRegister(VirtReg) && "Only map VirtRegs");
478 UserValue *&Leader = virtRegToEqClass[VirtReg];
479 Leader = UserValue::merge(Leader, EC);
482 UserValue *LDVImpl::lookupVirtReg(unsigned VirtReg) {
483 if (UserValue *UV = virtRegToEqClass.lookup(VirtReg))
484 return UV->getLeader();
488 bool LDVImpl::handleDebugValue(MachineInstr *MI, SlotIndex Idx) {
489 // DBG_VALUE loc, offset, variable
490 if (MI->getNumOperands() != 4 ||
491 !(MI->getOperand(1).isReg() || MI->getOperand(1).isImm()) ||
492 !MI->getOperand(2).isMetadata()) {
493 DEBUG(dbgs() << "Can't handle " << *MI);
497 // Get or create the UserValue for (variable,offset).
498 bool IsIndirect = MI->isIndirectDebugValue();
499 unsigned Offset = IsIndirect ? MI->getOperand(1).getImm() : 0;
500 const MDNode *Var = MI->getDebugVariable();
501 const MDNode *Expr = MI->getDebugExpression();
504 getUserValue(Var, Expr, Offset, IsIndirect, MI->getDebugLoc());
505 UV->addDef(Idx, MI->getOperand(0));
509 bool LDVImpl::collectDebugValues(MachineFunction &mf) {
510 bool Changed = false;
511 for (MachineFunction::iterator MFI = mf.begin(), MFE = mf.end(); MFI != MFE;
513 MachineBasicBlock *MBB = &*MFI;
514 for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
516 if (!MBBI->isDebugValue()) {
520 // DBG_VALUE has no slot index, use the previous instruction instead.
521 SlotIndex Idx = MBBI == MBB->begin() ?
522 LIS->getMBBStartIdx(MBB) :
523 LIS->getInstructionIndex(std::prev(MBBI)).getRegSlot();
524 // Handle consecutive DBG_VALUE instructions with the same slot index.
526 if (handleDebugValue(MBBI, Idx)) {
527 MBBI = MBB->erase(MBBI);
531 } while (MBBI != MBBE && MBBI->isDebugValue());
537 /// We only propagate DBG_VALUES locally here. LiveDebugValues performs a
538 /// data-flow analysis to propagate them beyond basic block boundaries.
539 void UserValue::extendDef(SlotIndex Idx, unsigned LocNo, LiveRange *LR,
540 const VNInfo *VNI, SmallVectorImpl<SlotIndex> *Kills,
541 LiveIntervals &LIS, MachineDominatorTree &MDT,
542 UserValueScopes &UVS) {
543 SlotIndex Start = Idx;
544 MachineBasicBlock *MBB = LIS.getMBBFromIndex(Start);
545 SlotIndex Stop = LIS.getMBBEndIdx(MBB);
546 LocMap::iterator I = locInts.find(Start);
548 // Limit to VNI's live range.
551 LiveInterval::Segment *Segment = LR->getSegmentContaining(Start);
552 if (!Segment || Segment->valno != VNI) {
554 Kills->push_back(Start);
557 if (Segment->end < Stop)
558 Stop = Segment->end, ToEnd = false;
561 // There could already be a short def at Start.
562 if (I.valid() && I.start() <= Start) {
563 // Stop when meeting a different location or an already extended interval.
564 Start = Start.getNextSlot();
565 if (I.value() != LocNo || I.stop() != Start)
567 // This is a one-slot placeholder. Just skip it.
571 // Limited by the next def.
572 if (I.valid() && I.start() < Stop)
573 Stop = I.start(), ToEnd = false;
574 // Limited by VNI's live range.
575 else if (!ToEnd && Kills)
576 Kills->push_back(Stop);
579 I.insert(Start, Stop, LocNo);
583 UserValue::addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
584 const SmallVectorImpl<SlotIndex> &Kills,
585 SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
586 MachineRegisterInfo &MRI, LiveIntervals &LIS) {
589 // Don't track copies from physregs, there are too many uses.
590 if (!TargetRegisterInfo::isVirtualRegister(LI->reg))
593 // Collect all the (vreg, valno) pairs that are copies of LI.
594 SmallVector<std::pair<LiveInterval*, const VNInfo*>, 8> CopyValues;
595 for (MachineOperand &MO : MRI.use_nodbg_operands(LI->reg)) {
596 MachineInstr *MI = MO.getParent();
597 // Copies of the full value.
598 if (MO.getSubReg() || !MI->isCopy())
600 unsigned DstReg = MI->getOperand(0).getReg();
602 // Don't follow copies to physregs. These are usually setting up call
603 // arguments, and the argument registers are always call clobbered. We are
604 // better off in the source register which could be a callee-saved register,
605 // or it could be spilled.
606 if (!TargetRegisterInfo::isVirtualRegister(DstReg))
609 // Is LocNo extended to reach this copy? If not, another def may be blocking
610 // it, or we are looking at a wrong value of LI.
611 SlotIndex Idx = LIS.getInstructionIndex(MI);
612 LocMap::iterator I = locInts.find(Idx.getRegSlot(true));
613 if (!I.valid() || I.value() != LocNo)
616 if (!LIS.hasInterval(DstReg))
618 LiveInterval *DstLI = &LIS.getInterval(DstReg);
619 const VNInfo *DstVNI = DstLI->getVNInfoAt(Idx.getRegSlot());
620 assert(DstVNI && DstVNI->def == Idx.getRegSlot() && "Bad copy value");
621 CopyValues.push_back(std::make_pair(DstLI, DstVNI));
624 if (CopyValues.empty())
627 DEBUG(dbgs() << "Got " << CopyValues.size() << " copies of " << *LI << '\n');
629 // Try to add defs of the copied values for each kill point.
630 for (unsigned i = 0, e = Kills.size(); i != e; ++i) {
631 SlotIndex Idx = Kills[i];
632 for (unsigned j = 0, e = CopyValues.size(); j != e; ++j) {
633 LiveInterval *DstLI = CopyValues[j].first;
634 const VNInfo *DstVNI = CopyValues[j].second;
635 if (DstLI->getVNInfoAt(Idx) != DstVNI)
637 // Check that there isn't already a def at Idx
638 LocMap::iterator I = locInts.find(Idx);
639 if (I.valid() && I.start() <= Idx)
641 DEBUG(dbgs() << "Kill at " << Idx << " covered by valno #"
642 << DstVNI->id << " in " << *DstLI << '\n');
643 MachineInstr *CopyMI = LIS.getInstructionFromIndex(DstVNI->def);
644 assert(CopyMI && CopyMI->isCopy() && "Bad copy value");
645 unsigned LocNo = getLocationNo(CopyMI->getOperand(0));
646 I.insert(Idx, Idx.getNextSlot(), LocNo);
647 NewDefs.push_back(std::make_pair(Idx, LocNo));
654 UserValue::computeIntervals(MachineRegisterInfo &MRI,
655 const TargetRegisterInfo &TRI,
657 MachineDominatorTree &MDT,
658 UserValueScopes &UVS) {
659 SmallVector<std::pair<SlotIndex, unsigned>, 16> Defs;
661 // Collect all defs to be extended (Skipping undefs).
662 for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I)
663 if (I.value() != ~0u)
664 Defs.push_back(std::make_pair(I.start(), I.value()));
666 // Extend all defs, and possibly add new ones along the way.
667 for (unsigned i = 0; i != Defs.size(); ++i) {
668 SlotIndex Idx = Defs[i].first;
669 unsigned LocNo = Defs[i].second;
670 const MachineOperand &Loc = locations[LocNo];
673 extendDef(Idx, LocNo, nullptr, nullptr, nullptr, LIS, MDT, UVS);
677 // Register locations are constrained to where the register value is live.
678 if (TargetRegisterInfo::isVirtualRegister(Loc.getReg())) {
679 LiveInterval *LI = nullptr;
680 const VNInfo *VNI = nullptr;
681 if (LIS.hasInterval(Loc.getReg())) {
682 LI = &LIS.getInterval(Loc.getReg());
683 VNI = LI->getVNInfoAt(Idx);
685 SmallVector<SlotIndex, 16> Kills;
686 extendDef(Idx, LocNo, LI, VNI, &Kills, LIS, MDT, UVS);
688 addDefsFromCopies(LI, LocNo, Kills, Defs, MRI, LIS);
692 // For physregs, use the live range of the first regunit as a guide.
693 unsigned Unit = *MCRegUnitIterator(Loc.getReg(), &TRI);
694 LiveRange *LR = &LIS.getRegUnit(Unit);
695 const VNInfo *VNI = LR->getVNInfoAt(Idx);
696 // Don't track copies from physregs, it is too expensive.
697 extendDef(Idx, LocNo, LR, VNI, nullptr, LIS, MDT, UVS);
700 // Finally, erase all the undefs.
701 for (LocMap::iterator I = locInts.begin(); I.valid();)
702 if (I.value() == ~0u)
708 void LDVImpl::computeIntervals() {
709 for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
710 UserValueScopes UVS(userValues[i]->getDebugLoc(), LS);
711 userValues[i]->computeIntervals(MF->getRegInfo(), *TRI, *LIS, *MDT, UVS);
712 userValues[i]->mapVirtRegs(this);
716 bool LDVImpl::runOnMachineFunction(MachineFunction &mf) {
719 LIS = &pass.getAnalysis<LiveIntervals>();
720 MDT = &pass.getAnalysis<MachineDominatorTree>();
721 TRI = mf.getSubtarget().getRegisterInfo();
723 DEBUG(dbgs() << "********** COMPUTING LIVE DEBUG VARIABLES: "
724 << mf.getName() << " **********\n");
726 bool Changed = collectDebugValues(mf);
728 DEBUG(print(dbgs()));
729 ModifiedMF = Changed;
733 static void removeDebugValues(MachineFunction &mf) {
734 for (MachineBasicBlock &MBB : mf) {
735 for (auto MBBI = MBB.begin(), MBBE = MBB.end(); MBBI != MBBE; ) {
736 if (!MBBI->isDebugValue()) {
740 MBBI = MBB.erase(MBBI);
745 bool LiveDebugVariables::runOnMachineFunction(MachineFunction &mf) {
748 if (!mf.getFunction()->getSubprogram()) {
749 removeDebugValues(mf);
753 pImpl = new LDVImpl(this);
754 return static_cast<LDVImpl*>(pImpl)->runOnMachineFunction(mf);
757 void LiveDebugVariables::releaseMemory() {
759 static_cast<LDVImpl*>(pImpl)->clear();
762 LiveDebugVariables::~LiveDebugVariables() {
764 delete static_cast<LDVImpl*>(pImpl);
767 //===----------------------------------------------------------------------===//
768 // Live Range Splitting
769 //===----------------------------------------------------------------------===//
772 UserValue::splitLocation(unsigned OldLocNo, ArrayRef<unsigned> NewRegs,
773 LiveIntervals& LIS) {
775 dbgs() << "Splitting Loc" << OldLocNo << '\t';
776 print(dbgs(), nullptr);
778 bool DidChange = false;
779 LocMap::iterator LocMapI;
780 LocMapI.setMap(locInts);
781 for (unsigned i = 0; i != NewRegs.size(); ++i) {
782 LiveInterval *LI = &LIS.getInterval(NewRegs[i]);
786 // Don't allocate the new LocNo until it is needed.
787 unsigned NewLocNo = ~0u;
789 // Iterate over the overlaps between locInts and LI.
790 LocMapI.find(LI->beginIndex());
791 if (!LocMapI.valid())
793 LiveInterval::iterator LII = LI->advanceTo(LI->begin(), LocMapI.start());
794 LiveInterval::iterator LIE = LI->end();
795 while (LocMapI.valid() && LII != LIE) {
796 // At this point, we know that LocMapI.stop() > LII->start.
797 LII = LI->advanceTo(LII, LocMapI.start());
801 // Now LII->end > LocMapI.start(). Do we have an overlap?
802 if (LocMapI.value() == OldLocNo && LII->start < LocMapI.stop()) {
803 // Overlapping correct location. Allocate NewLocNo now.
804 if (NewLocNo == ~0u) {
805 MachineOperand MO = MachineOperand::CreateReg(LI->reg, false);
806 MO.setSubReg(locations[OldLocNo].getSubReg());
807 NewLocNo = getLocationNo(MO);
811 SlotIndex LStart = LocMapI.start();
812 SlotIndex LStop = LocMapI.stop();
814 // Trim LocMapI down to the LII overlap.
815 if (LStart < LII->start)
816 LocMapI.setStartUnchecked(LII->start);
817 if (LStop > LII->end)
818 LocMapI.setStopUnchecked(LII->end);
820 // Change the value in the overlap. This may trigger coalescing.
821 LocMapI.setValue(NewLocNo);
823 // Re-insert any removed OldLocNo ranges.
824 if (LStart < LocMapI.start()) {
825 LocMapI.insert(LStart, LocMapI.start(), OldLocNo);
827 assert(LocMapI.valid() && "Unexpected coalescing");
829 if (LStop > LocMapI.stop()) {
831 LocMapI.insert(LII->end, LStop, OldLocNo);
836 // Advance to the next overlap.
837 if (LII->end < LocMapI.stop()) {
840 LocMapI.advanceTo(LII->start);
843 if (!LocMapI.valid())
845 LII = LI->advanceTo(LII, LocMapI.start());
850 // Finally, remove any remaining OldLocNo intervals and OldLocNo itself.
851 locations.erase(locations.begin() + OldLocNo);
853 while (LocMapI.valid()) {
854 unsigned v = LocMapI.value();
856 DEBUG(dbgs() << "Erasing [" << LocMapI.start() << ';'
857 << LocMapI.stop() << ")\n");
861 LocMapI.setValueUnchecked(v-1);
866 DEBUG({dbgs() << "Split result: \t"; print(dbgs(), nullptr);});
871 UserValue::splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs,
872 LiveIntervals &LIS) {
873 bool DidChange = false;
874 // Split locations referring to OldReg. Iterate backwards so splitLocation can
875 // safely erase unused locations.
876 for (unsigned i = locations.size(); i ; --i) {
877 unsigned LocNo = i-1;
878 const MachineOperand *Loc = &locations[LocNo];
879 if (!Loc->isReg() || Loc->getReg() != OldReg)
881 DidChange |= splitLocation(LocNo, NewRegs, LIS);
886 void LDVImpl::splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs) {
887 bool DidChange = false;
888 for (UserValue *UV = lookupVirtReg(OldReg); UV; UV = UV->getNext())
889 DidChange |= UV->splitRegister(OldReg, NewRegs, *LIS);
894 // Map all of the new virtual registers.
895 UserValue *UV = lookupVirtReg(OldReg);
896 for (unsigned i = 0; i != NewRegs.size(); ++i)
897 mapVirtReg(NewRegs[i], UV);
900 void LiveDebugVariables::
901 splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs, LiveIntervals &LIS) {
903 static_cast<LDVImpl*>(pImpl)->splitRegister(OldReg, NewRegs);
907 UserValue::rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI) {
908 // Iterate over locations in reverse makes it easier to handle coalescing.
909 for (unsigned i = locations.size(); i ; --i) {
910 unsigned LocNo = i-1;
911 MachineOperand &Loc = locations[LocNo];
912 // Only virtual registers are rewritten.
913 if (!Loc.isReg() || !Loc.getReg() ||
914 !TargetRegisterInfo::isVirtualRegister(Loc.getReg()))
916 unsigned VirtReg = Loc.getReg();
917 if (VRM.isAssignedReg(VirtReg) &&
918 TargetRegisterInfo::isPhysicalRegister(VRM.getPhys(VirtReg))) {
919 // This can create a %noreg operand in rare cases when the sub-register
920 // index is no longer available. That means the user value is in a
921 // non-existent sub-register, and %noreg is exactly what we want.
922 Loc.substPhysReg(VRM.getPhys(VirtReg), TRI);
923 } else if (VRM.getStackSlot(VirtReg) != VirtRegMap::NO_STACK_SLOT) {
924 // FIXME: Translate SubIdx to a stackslot offset.
925 Loc = MachineOperand::CreateFI(VRM.getStackSlot(VirtReg));
930 coalesceLocation(LocNo);
934 /// findInsertLocation - Find an iterator for inserting a DBG_VALUE
936 static MachineBasicBlock::iterator
937 findInsertLocation(MachineBasicBlock *MBB, SlotIndex Idx,
938 LiveIntervals &LIS) {
939 SlotIndex Start = LIS.getMBBStartIdx(MBB);
940 Idx = Idx.getBaseIndex();
942 // Try to find an insert location by going backwards from Idx.
944 while (!(MI = LIS.getInstructionFromIndex(Idx))) {
945 // We've reached the beginning of MBB.
947 MachineBasicBlock::iterator I = MBB->SkipPHIsAndLabels(MBB->begin());
950 Idx = Idx.getPrevIndex();
953 // Don't insert anything after the first terminator, though.
954 return MI->isTerminator() ? MBB->getFirstTerminator() :
955 std::next(MachineBasicBlock::iterator(MI));
958 void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx,
961 const TargetInstrInfo &TII) {
962 MachineBasicBlock::iterator I = findInsertLocation(MBB, Idx, LIS);
963 MachineOperand &Loc = locations[LocNo];
964 ++NumInsertedDebugValues;
966 assert(cast<DILocalVariable>(Variable)
967 ->isValidLocationForIntrinsic(getDebugLoc()) &&
968 "Expected inlined-at fields to agree");
970 BuildMI(*MBB, I, getDebugLoc(), TII.get(TargetOpcode::DBG_VALUE),
971 IsIndirect, Loc.getReg(), offset, Variable, Expression);
973 BuildMI(*MBB, I, getDebugLoc(), TII.get(TargetOpcode::DBG_VALUE))
976 .addMetadata(Variable)
977 .addMetadata(Expression);
980 void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
981 const TargetInstrInfo &TII) {
982 MachineFunction::iterator MFEnd = VRM->getMachineFunction().end();
984 for (LocMap::const_iterator I = locInts.begin(); I.valid();) {
985 SlotIndex Start = I.start();
986 SlotIndex Stop = I.stop();
987 unsigned LocNo = I.value();
988 DEBUG(dbgs() << "\t[" << Start << ';' << Stop << "):" << LocNo);
989 MachineFunction::iterator MBB = LIS.getMBBFromIndex(Start)->getIterator();
990 SlotIndex MBBEnd = LIS.getMBBEndIdx(&*MBB);
992 DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
993 insertDebugValue(&*MBB, Start, LocNo, LIS, TII);
994 // This interval may span multiple basic blocks.
995 // Insert a DBG_VALUE into each one.
996 while(Stop > MBBEnd) {
997 // Move to the next block.
1001 MBBEnd = LIS.getMBBEndIdx(&*MBB);
1002 DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
1003 insertDebugValue(&*MBB, Start, LocNo, LIS, TII);
1005 DEBUG(dbgs() << '\n');
1013 void LDVImpl::emitDebugValues(VirtRegMap *VRM) {
1014 DEBUG(dbgs() << "********** EMITTING LIVE DEBUG VARIABLES **********\n");
1017 const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
1018 for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
1019 DEBUG(userValues[i]->print(dbgs(), TRI));
1020 userValues[i]->rewriteLocations(*VRM, *TRI);
1021 userValues[i]->emitDebugValues(VRM, *LIS, *TII);
1026 void LiveDebugVariables::emitDebugValues(VirtRegMap *VRM) {
1028 static_cast<LDVImpl*>(pImpl)->emitDebugValues(VRM);
1031 bool LiveDebugVariables::doInitialization(Module &M) {
1032 return Pass::doInitialization(M);
1036 void LiveDebugVariables::dump() {
1038 static_cast<LDVImpl*>(pImpl)->print(dbgs());