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 #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/Target/TargetInstrInfo.h" 40 #include "llvm/Target/TargetMachine.h" 41 #include "llvm/Target/TargetRegisterInfo.h" 42 43 #include <memory> 44 45 using namespace llvm; 46 47 #define DEBUG_TYPE "livedebug" 48 49 static cl::opt<bool> 50 EnableLDV("live-debug-variables", cl::init(true), 51 cl::desc("Enable the live debug variables pass"), cl::Hidden); 52 53 STATISTIC(NumInsertedDebugValues, "Number of DBG_VALUEs inserted"); 54 char LiveDebugVariables::ID = 0; 55 56 INITIALIZE_PASS_BEGIN(LiveDebugVariables, "livedebugvars", 57 "Debug Variable Analysis", false, false) 58 INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree) 59 INITIALIZE_PASS_DEPENDENCY(LiveIntervals) 60 INITIALIZE_PASS_END(LiveDebugVariables, "livedebugvars", 61 "Debug Variable Analysis", false, false) 62 63 void LiveDebugVariables::getAnalysisUsage(AnalysisUsage &AU) const { 64 AU.addRequired<MachineDominatorTree>(); 65 AU.addRequiredTransitive<LiveIntervals>(); 66 AU.setPreservesAll(); 67 MachineFunctionPass::getAnalysisUsage(AU); 68 } 69 70 LiveDebugVariables::LiveDebugVariables() : MachineFunctionPass(ID), pImpl(nullptr) { 71 initializeLiveDebugVariablesPass(*PassRegistry::getPassRegistry()); 72 } 73 74 /// LocMap - Map of where a user value is live, and its location. 75 typedef IntervalMap<SlotIndex, unsigned, 4> LocMap; 76 77 namespace { 78 /// UserValueScopes - Keeps track of lexical scopes associated with a 79 /// user value's source location. 80 class UserValueScopes { 81 DebugLoc DL; 82 LexicalScopes &LS; 83 SmallPtrSet<const MachineBasicBlock *, 4> LBlocks; 84 85 public: 86 UserValueScopes(DebugLoc D, LexicalScopes &L) : DL(D), LS(L) {} 87 88 /// dominates - Return true if current scope dominates at least one machine 89 /// instruction in a given machine basic block. 90 bool dominates(MachineBasicBlock *MBB) { 91 if (LBlocks.empty()) 92 LS.getMachineBasicBlocks(DL, LBlocks); 93 if (LBlocks.count(MBB) != 0 || LS.dominates(DL, MBB)) 94 return true; 95 return false; 96 } 97 }; 98 } // end anonymous namespace 99 100 /// UserValue - A user value is a part of a debug info user variable. 101 /// 102 /// A DBG_VALUE instruction notes that (a sub-register of) a virtual register 103 /// holds part of a user variable. The part is identified by a byte offset. 104 /// 105 /// UserValues are grouped into equivalence classes for easier searching. Two 106 /// user values are related if they refer to the same variable, or if they are 107 /// held by the same virtual register. The equivalence class is the transitive 108 /// closure of that relation. 109 namespace { 110 class LDVImpl; 111 class UserValue { 112 const MDNode *variable; ///< The debug info variable we are part of. 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. 119 120 /// Numbered locations referenced by locmap. 121 SmallVector<MachineOperand, 4> locations; 122 123 /// Map of slot indices where this value is live. 124 LocMap locInts; 125 126 /// 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); 130 131 /// 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); 134 135 /// 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, 138 LiveIntervals &LIS); 139 140 public: 141 /// UserValue - Create a new UserValue. 142 UserValue(const MDNode *var, unsigned o, bool i, DebugLoc L, 143 LocMap::Allocator &alloc) 144 : variable(var), offset(o), IsIndirect(i), dl(L), leader(this), 145 next(nullptr), locInts(alloc) 146 {} 147 148 /// getLeader - Get the leader of this value's equivalence class. 149 UserValue *getLeader() { 150 UserValue *l = leader; 151 while (l != l->leader) 152 l = l->leader; 153 return leader = l; 154 } 155 156 /// getNext - Return the next UserValue in the equivalence class. 157 UserValue *getNext() const { return next; } 158 159 /// match - Does this UserValue match the parameters? 160 bool match(const MDNode *Var, unsigned Offset, bool indirect) const { 161 return Var == variable && Offset == offset && indirect == IsIndirect; 162 } 163 164 /// merge - Merge equivalence classes. 165 static UserValue *merge(UserValue *L1, UserValue *L2) { 166 L2 = L2->getLeader(); 167 if (!L1) 168 return L2; 169 L1 = L1->getLeader(); 170 if (L1 == L2) 171 return L1; 172 // Splice L2 before L1's members. 173 UserValue *End = L2; 174 while (End->next) 175 End->leader = L1, End = End->next; 176 End->leader = L1; 177 End->next = L1->next; 178 L1->next = L2; 179 return L1; 180 } 181 182 /// getLocationNo - Return the location number that matches Loc. 183 unsigned getLocationNo(const MachineOperand &LocMO) { 184 if (LocMO.isReg()) { 185 if (LocMO.getReg() == 0) 186 return ~0u; 187 // For register locations we dont care about use/def and other flags. 188 for (unsigned i = 0, e = locations.size(); i != e; ++i) 189 if (locations[i].isReg() && 190 locations[i].getReg() == LocMO.getReg() && 191 locations[i].getSubReg() == LocMO.getSubReg()) 192 return i; 193 } else 194 for (unsigned i = 0, e = locations.size(); i != e; ++i) 195 if (LocMO.isIdenticalTo(locations[i])) 196 return i; 197 locations.push_back(LocMO); 198 // We are storing a MachineOperand outside a MachineInstr. 199 locations.back().clearParent(); 200 // Don't store def operands. 201 if (locations.back().isReg()) 202 locations.back().setIsUse(); 203 return locations.size() - 1; 204 } 205 206 /// mapVirtRegs - Ensure that all virtual register locations are mapped. 207 void mapVirtRegs(LDVImpl *LDV); 208 209 /// addDef - Add a definition point to this value. 210 void addDef(SlotIndex Idx, const MachineOperand &LocMO) { 211 // Add a singular (Idx,Idx) -> Loc mapping. 212 LocMap::iterator I = locInts.find(Idx); 213 if (!I.valid() || I.start() != Idx) 214 I.insert(Idx, Idx.getNextSlot(), getLocationNo(LocMO)); 215 else 216 // A later DBG_VALUE at the same SlotIndex overrides the old location. 217 I.setValue(getLocationNo(LocMO)); 218 } 219 220 /// extendDef - Extend the current definition as far as possible down the 221 /// dominator tree. Stop when meeting an existing def or when leaving the live 222 /// range of VNI. 223 /// End points where VNI is no longer live are added to Kills. 224 /// @param Idx Starting point for the definition. 225 /// @param LocNo Location number to propagate. 226 /// @param LR Restrict liveness to where LR has the value VNI. May be null. 227 /// @param VNI When LR is not null, this is the value to restrict to. 228 /// @param Kills Append end points of VNI's live range to Kills. 229 /// @param LIS Live intervals analysis. 230 /// @param MDT Dominator tree. 231 void extendDef(SlotIndex Idx, unsigned LocNo, 232 LiveRange *LR, const VNInfo *VNI, 233 SmallVectorImpl<SlotIndex> *Kills, 234 LiveIntervals &LIS, MachineDominatorTree &MDT, 235 UserValueScopes &UVS); 236 237 /// addDefsFromCopies - The value in LI/LocNo may be copies to other 238 /// registers. Determine if any of the copies are available at the kill 239 /// points, and add defs if possible. 240 /// @param LI Scan for copies of the value in LI->reg. 241 /// @param LocNo Location number of LI->reg. 242 /// @param Kills Points where the range of LocNo could be extended. 243 /// @param NewDefs Append (Idx, LocNo) of inserted defs here. 244 void addDefsFromCopies(LiveInterval *LI, unsigned LocNo, 245 const SmallVectorImpl<SlotIndex> &Kills, 246 SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs, 247 MachineRegisterInfo &MRI, 248 LiveIntervals &LIS); 249 250 /// computeIntervals - Compute the live intervals of all locations after 251 /// collecting all their def points. 252 void computeIntervals(MachineRegisterInfo &MRI, const TargetRegisterInfo &TRI, 253 LiveIntervals &LIS, MachineDominatorTree &MDT, 254 UserValueScopes &UVS); 255 256 /// splitRegister - Replace OldReg ranges with NewRegs ranges where NewRegs is 257 /// live. Returns true if any changes were made. 258 bool splitRegister(unsigned OldLocNo, ArrayRef<unsigned> NewRegs, 259 LiveIntervals &LIS); 260 261 /// rewriteLocations - Rewrite virtual register locations according to the 262 /// provided virtual register map. 263 void rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI); 264 265 /// emitDebugValues - Recreate DBG_VALUE instruction from data structures. 266 void emitDebugValues(VirtRegMap *VRM, 267 LiveIntervals &LIS, const TargetInstrInfo &TRI); 268 269 /// findDebugLoc - Return DebugLoc used for this DBG_VALUE instruction. A 270 /// variable may have more than one corresponding DBG_VALUE instructions. 271 /// Only first one needs DebugLoc to identify variable's lexical scope 272 /// in source file. 273 DebugLoc findDebugLoc(); 274 275 /// getDebugLoc - Return DebugLoc of this UserValue. 276 DebugLoc getDebugLoc() { return dl;} 277 void print(raw_ostream&, const TargetMachine*); 278 }; 279 } // namespace 280 281 /// LDVImpl - Implementation of the LiveDebugVariables pass. 282 namespace { 283 class LDVImpl { 284 LiveDebugVariables &pass; 285 LocMap::Allocator allocator; 286 MachineFunction *MF; 287 LiveIntervals *LIS; 288 LexicalScopes LS; 289 MachineDominatorTree *MDT; 290 const TargetRegisterInfo *TRI; 291 292 /// Whether emitDebugValues is called. 293 bool EmitDone; 294 /// Whether the machine function is modified during the pass. 295 bool ModifiedMF; 296 297 /// userValues - All allocated UserValue instances. 298 SmallVector<std::unique_ptr<UserValue>, 8> userValues; 299 300 /// Map virtual register to eq class leader. 301 typedef DenseMap<unsigned, UserValue*> VRMap; 302 VRMap virtRegToEqClass; 303 304 /// Map user variable to eq class leader. 305 typedef DenseMap<const MDNode *, UserValue*> UVMap; 306 UVMap userVarMap; 307 308 /// getUserValue - Find or create a UserValue. 309 UserValue *getUserValue(const MDNode *Var, unsigned Offset, 310 bool IsIndirect, DebugLoc DL); 311 312 /// lookupVirtReg - Find the EC leader for VirtReg or null. 313 UserValue *lookupVirtReg(unsigned VirtReg); 314 315 /// handleDebugValue - Add DBG_VALUE instruction to our maps. 316 /// @param MI DBG_VALUE instruction 317 /// @param Idx Last valid SLotIndex before instruction. 318 /// @return True if the DBG_VALUE instruction should be deleted. 319 bool handleDebugValue(MachineInstr *MI, SlotIndex Idx); 320 321 /// collectDebugValues - Collect and erase all DBG_VALUE instructions, adding 322 /// a UserValue def for each instruction. 323 /// @param mf MachineFunction to be scanned. 324 /// @return True if any debug values were found. 325 bool collectDebugValues(MachineFunction &mf); 326 327 /// computeIntervals - Compute the live intervals of all user values after 328 /// collecting all their def points. 329 void computeIntervals(); 330 331 public: 332 LDVImpl(LiveDebugVariables *ps) 333 : pass(*ps), MF(nullptr), EmitDone(false), ModifiedMF(false) {} 334 bool runOnMachineFunction(MachineFunction &mf); 335 336 /// clear - Release all memory. 337 void clear() { 338 MF = nullptr; 339 userValues.clear(); 340 virtRegToEqClass.clear(); 341 userVarMap.clear(); 342 // Make sure we call emitDebugValues if the machine function was modified. 343 assert((!ModifiedMF || EmitDone) && 344 "Dbg values are not emitted in LDV"); 345 EmitDone = false; 346 ModifiedMF = false; 347 } 348 349 /// mapVirtReg - Map virtual register to an equivalence class. 350 void mapVirtReg(unsigned VirtReg, UserValue *EC); 351 352 /// splitRegister - Replace all references to OldReg with NewRegs. 353 void splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs); 354 355 /// emitDebugValues - Recreate DBG_VALUE instruction from data structures. 356 void emitDebugValues(VirtRegMap *VRM); 357 358 void print(raw_ostream&); 359 }; 360 } // namespace 361 362 void UserValue::print(raw_ostream &OS, const TargetMachine *TM) { 363 DIVariable DV(variable); 364 OS << "!\""; 365 DV.printExtendedName(OS); 366 OS << "\"\t"; 367 if (offset) 368 OS << '+' << offset; 369 for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) { 370 OS << " [" << I.start() << ';' << I.stop() << "):"; 371 if (I.value() == ~0u) 372 OS << "undef"; 373 else 374 OS << I.value(); 375 } 376 for (unsigned i = 0, e = locations.size(); i != e; ++i) { 377 OS << " Loc" << i << '='; 378 locations[i].print(OS, TM); 379 } 380 OS << '\n'; 381 } 382 383 void LDVImpl::print(raw_ostream &OS) { 384 OS << "********** DEBUG VARIABLES **********\n"; 385 for (unsigned i = 0, e = userValues.size(); i != e; ++i) 386 userValues[i]->print(OS, &MF->getTarget()); 387 } 388 389 void UserValue::coalesceLocation(unsigned LocNo) { 390 unsigned KeepLoc = 0; 391 for (unsigned e = locations.size(); KeepLoc != e; ++KeepLoc) { 392 if (KeepLoc == LocNo) 393 continue; 394 if (locations[KeepLoc].isIdenticalTo(locations[LocNo])) 395 break; 396 } 397 // No matches. 398 if (KeepLoc == locations.size()) 399 return; 400 401 // Keep the smaller location, erase the larger one. 402 unsigned EraseLoc = LocNo; 403 if (KeepLoc > EraseLoc) 404 std::swap(KeepLoc, EraseLoc); 405 locations.erase(locations.begin() + EraseLoc); 406 407 // Rewrite values. 408 for (LocMap::iterator I = locInts.begin(); I.valid(); ++I) { 409 unsigned v = I.value(); 410 if (v == EraseLoc) 411 I.setValue(KeepLoc); // Coalesce when possible. 412 else if (v > EraseLoc) 413 I.setValueUnchecked(v-1); // Avoid coalescing with untransformed values. 414 } 415 } 416 417 void UserValue::mapVirtRegs(LDVImpl *LDV) { 418 for (unsigned i = 0, e = locations.size(); i != e; ++i) 419 if (locations[i].isReg() && 420 TargetRegisterInfo::isVirtualRegister(locations[i].getReg())) 421 LDV->mapVirtReg(locations[i].getReg(), this); 422 } 423 424 UserValue *LDVImpl::getUserValue(const MDNode *Var, unsigned Offset, 425 bool IsIndirect, DebugLoc DL) { 426 UserValue *&Leader = userVarMap[Var]; 427 if (Leader) { 428 UserValue *UV = Leader->getLeader(); 429 Leader = UV; 430 for (; UV; UV = UV->getNext()) 431 if (UV->match(Var, Offset, IsIndirect)) 432 return UV; 433 } 434 435 userValues.push_back( 436 make_unique<UserValue>(Var, Offset, IsIndirect, DL, allocator)); 437 UserValue *UV = userValues.back().get(); 438 Leader = UserValue::merge(Leader, UV); 439 return UV; 440 } 441 442 void LDVImpl::mapVirtReg(unsigned VirtReg, UserValue *EC) { 443 assert(TargetRegisterInfo::isVirtualRegister(VirtReg) && "Only map VirtRegs"); 444 UserValue *&Leader = virtRegToEqClass[VirtReg]; 445 Leader = UserValue::merge(Leader, EC); 446 } 447 448 UserValue *LDVImpl::lookupVirtReg(unsigned VirtReg) { 449 if (UserValue *UV = virtRegToEqClass.lookup(VirtReg)) 450 return UV->getLeader(); 451 return nullptr; 452 } 453 454 bool LDVImpl::handleDebugValue(MachineInstr *MI, SlotIndex Idx) { 455 // DBG_VALUE loc, offset, variable 456 if (MI->getNumOperands() != 3 || 457 !(MI->getOperand(1).isReg() || MI->getOperand(1).isImm()) || 458 !MI->getOperand(2).isMetadata()) { 459 DEBUG(dbgs() << "Can't handle " << *MI); 460 return false; 461 } 462 463 // Get or create the UserValue for (variable,offset). 464 bool IsIndirect = MI->isIndirectDebugValue(); 465 unsigned Offset = IsIndirect ? MI->getOperand(1).getImm() : 0; 466 const MDNode *Var = MI->getOperand(2).getMetadata(); 467 //here. 468 UserValue *UV = getUserValue(Var, Offset, IsIndirect, MI->getDebugLoc()); 469 UV->addDef(Idx, MI->getOperand(0)); 470 return true; 471 } 472 473 bool LDVImpl::collectDebugValues(MachineFunction &mf) { 474 bool Changed = false; 475 for (MachineFunction::iterator MFI = mf.begin(), MFE = mf.end(); MFI != MFE; 476 ++MFI) { 477 MachineBasicBlock *MBB = MFI; 478 for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end(); 479 MBBI != MBBE;) { 480 if (!MBBI->isDebugValue()) { 481 ++MBBI; 482 continue; 483 } 484 // DBG_VALUE has no slot index, use the previous instruction instead. 485 SlotIndex Idx = MBBI == MBB->begin() ? 486 LIS->getMBBStartIdx(MBB) : 487 LIS->getInstructionIndex(std::prev(MBBI)).getRegSlot(); 488 // Handle consecutive DBG_VALUE instructions with the same slot index. 489 do { 490 if (handleDebugValue(MBBI, Idx)) { 491 MBBI = MBB->erase(MBBI); 492 Changed = true; 493 } else 494 ++MBBI; 495 } while (MBBI != MBBE && MBBI->isDebugValue()); 496 } 497 } 498 return Changed; 499 } 500 501 void UserValue::extendDef(SlotIndex Idx, unsigned LocNo, 502 LiveRange *LR, const VNInfo *VNI, 503 SmallVectorImpl<SlotIndex> *Kills, 504 LiveIntervals &LIS, MachineDominatorTree &MDT, 505 UserValueScopes &UVS) { 506 SmallVector<SlotIndex, 16> Todo; 507 Todo.push_back(Idx); 508 do { 509 SlotIndex Start = Todo.pop_back_val(); 510 MachineBasicBlock *MBB = LIS.getMBBFromIndex(Start); 511 SlotIndex Stop = LIS.getMBBEndIdx(MBB); 512 LocMap::iterator I = locInts.find(Start); 513 514 // Limit to VNI's live range. 515 bool ToEnd = true; 516 if (LR && VNI) { 517 LiveInterval::Segment *Segment = LR->getSegmentContaining(Start); 518 if (!Segment || Segment->valno != VNI) { 519 if (Kills) 520 Kills->push_back(Start); 521 continue; 522 } 523 if (Segment->end < Stop) 524 Stop = Segment->end, ToEnd = false; 525 } 526 527 // There could already be a short def at Start. 528 if (I.valid() && I.start() <= Start) { 529 // Stop when meeting a different location or an already extended interval. 530 Start = Start.getNextSlot(); 531 if (I.value() != LocNo || I.stop() != Start) 532 continue; 533 // This is a one-slot placeholder. Just skip it. 534 ++I; 535 } 536 537 // Limited by the next def. 538 if (I.valid() && I.start() < Stop) 539 Stop = I.start(), ToEnd = false; 540 // Limited by VNI's live range. 541 else if (!ToEnd && Kills) 542 Kills->push_back(Stop); 543 544 if (Start >= Stop) 545 continue; 546 547 I.insert(Start, Stop, LocNo); 548 549 // If we extended to the MBB end, propagate down the dominator tree. 550 if (!ToEnd) 551 continue; 552 const std::vector<MachineDomTreeNode*> &Children = 553 MDT.getNode(MBB)->getChildren(); 554 for (unsigned i = 0, e = Children.size(); i != e; ++i) { 555 MachineBasicBlock *MBB = Children[i]->getBlock(); 556 if (UVS.dominates(MBB)) 557 Todo.push_back(LIS.getMBBStartIdx(MBB)); 558 } 559 } while (!Todo.empty()); 560 } 561 562 void 563 UserValue::addDefsFromCopies(LiveInterval *LI, unsigned LocNo, 564 const SmallVectorImpl<SlotIndex> &Kills, 565 SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs, 566 MachineRegisterInfo &MRI, LiveIntervals &LIS) { 567 if (Kills.empty()) 568 return; 569 // Don't track copies from physregs, there are too many uses. 570 if (!TargetRegisterInfo::isVirtualRegister(LI->reg)) 571 return; 572 573 // Collect all the (vreg, valno) pairs that are copies of LI. 574 SmallVector<std::pair<LiveInterval*, const VNInfo*>, 8> CopyValues; 575 for (MachineOperand &MO : MRI.use_nodbg_operands(LI->reg)) { 576 MachineInstr *MI = MO.getParent(); 577 // Copies of the full value. 578 if (MO.getSubReg() || !MI->isCopy()) 579 continue; 580 unsigned DstReg = MI->getOperand(0).getReg(); 581 582 // Don't follow copies to physregs. These are usually setting up call 583 // arguments, and the argument registers are always call clobbered. We are 584 // better off in the source register which could be a callee-saved register, 585 // or it could be spilled. 586 if (!TargetRegisterInfo::isVirtualRegister(DstReg)) 587 continue; 588 589 // Is LocNo extended to reach this copy? If not, another def may be blocking 590 // it, or we are looking at a wrong value of LI. 591 SlotIndex Idx = LIS.getInstructionIndex(MI); 592 LocMap::iterator I = locInts.find(Idx.getRegSlot(true)); 593 if (!I.valid() || I.value() != LocNo) 594 continue; 595 596 if (!LIS.hasInterval(DstReg)) 597 continue; 598 LiveInterval *DstLI = &LIS.getInterval(DstReg); 599 const VNInfo *DstVNI = DstLI->getVNInfoAt(Idx.getRegSlot()); 600 assert(DstVNI && DstVNI->def == Idx.getRegSlot() && "Bad copy value"); 601 CopyValues.push_back(std::make_pair(DstLI, DstVNI)); 602 } 603 604 if (CopyValues.empty()) 605 return; 606 607 DEBUG(dbgs() << "Got " << CopyValues.size() << " copies of " << *LI << '\n'); 608 609 // Try to add defs of the copied values for each kill point. 610 for (unsigned i = 0, e = Kills.size(); i != e; ++i) { 611 SlotIndex Idx = Kills[i]; 612 for (unsigned j = 0, e = CopyValues.size(); j != e; ++j) { 613 LiveInterval *DstLI = CopyValues[j].first; 614 const VNInfo *DstVNI = CopyValues[j].second; 615 if (DstLI->getVNInfoAt(Idx) != DstVNI) 616 continue; 617 // Check that there isn't already a def at Idx 618 LocMap::iterator I = locInts.find(Idx); 619 if (I.valid() && I.start() <= Idx) 620 continue; 621 DEBUG(dbgs() << "Kill at " << Idx << " covered by valno #" 622 << DstVNI->id << " in " << *DstLI << '\n'); 623 MachineInstr *CopyMI = LIS.getInstructionFromIndex(DstVNI->def); 624 assert(CopyMI && CopyMI->isCopy() && "Bad copy value"); 625 unsigned LocNo = getLocationNo(CopyMI->getOperand(0)); 626 I.insert(Idx, Idx.getNextSlot(), LocNo); 627 NewDefs.push_back(std::make_pair(Idx, LocNo)); 628 break; 629 } 630 } 631 } 632 633 void 634 UserValue::computeIntervals(MachineRegisterInfo &MRI, 635 const TargetRegisterInfo &TRI, 636 LiveIntervals &LIS, 637 MachineDominatorTree &MDT, 638 UserValueScopes &UVS) { 639 SmallVector<std::pair<SlotIndex, unsigned>, 16> Defs; 640 641 // Collect all defs to be extended (Skipping undefs). 642 for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) 643 if (I.value() != ~0u) 644 Defs.push_back(std::make_pair(I.start(), I.value())); 645 646 // Extend all defs, and possibly add new ones along the way. 647 for (unsigned i = 0; i != Defs.size(); ++i) { 648 SlotIndex Idx = Defs[i].first; 649 unsigned LocNo = Defs[i].second; 650 const MachineOperand &Loc = locations[LocNo]; 651 652 if (!Loc.isReg()) { 653 extendDef(Idx, LocNo, nullptr, nullptr, nullptr, LIS, MDT, UVS); 654 continue; 655 } 656 657 // Register locations are constrained to where the register value is live. 658 if (TargetRegisterInfo::isVirtualRegister(Loc.getReg())) { 659 LiveInterval *LI = nullptr; 660 const VNInfo *VNI = nullptr; 661 if (LIS.hasInterval(Loc.getReg())) { 662 LI = &LIS.getInterval(Loc.getReg()); 663 VNI = LI->getVNInfoAt(Idx); 664 } 665 SmallVector<SlotIndex, 16> Kills; 666 extendDef(Idx, LocNo, LI, VNI, &Kills, LIS, MDT, UVS); 667 if (LI) 668 addDefsFromCopies(LI, LocNo, Kills, Defs, MRI, LIS); 669 continue; 670 } 671 672 // For physregs, use the live range of the first regunit as a guide. 673 unsigned Unit = *MCRegUnitIterator(Loc.getReg(), &TRI); 674 LiveRange *LR = &LIS.getRegUnit(Unit); 675 const VNInfo *VNI = LR->getVNInfoAt(Idx); 676 // Don't track copies from physregs, it is too expensive. 677 extendDef(Idx, LocNo, LR, VNI, nullptr, LIS, MDT, UVS); 678 } 679 680 // Finally, erase all the undefs. 681 for (LocMap::iterator I = locInts.begin(); I.valid();) 682 if (I.value() == ~0u) 683 I.erase(); 684 else 685 ++I; 686 } 687 688 void LDVImpl::computeIntervals() { 689 for (unsigned i = 0, e = userValues.size(); i != e; ++i) { 690 UserValueScopes UVS(userValues[i]->getDebugLoc(), LS); 691 userValues[i]->computeIntervals(MF->getRegInfo(), *TRI, *LIS, *MDT, UVS); 692 userValues[i]->mapVirtRegs(this); 693 } 694 } 695 696 bool LDVImpl::runOnMachineFunction(MachineFunction &mf) { 697 clear(); 698 MF = &mf; 699 LIS = &pass.getAnalysis<LiveIntervals>(); 700 MDT = &pass.getAnalysis<MachineDominatorTree>(); 701 TRI = mf.getTarget().getRegisterInfo(); 702 LS.initialize(mf); 703 DEBUG(dbgs() << "********** COMPUTING LIVE DEBUG VARIABLES: " 704 << mf.getName() << " **********\n"); 705 706 bool Changed = collectDebugValues(mf); 707 computeIntervals(); 708 DEBUG(print(dbgs())); 709 ModifiedMF = Changed; 710 return Changed; 711 } 712 713 bool LiveDebugVariables::runOnMachineFunction(MachineFunction &mf) { 714 if (!EnableLDV) 715 return false; 716 if (!FunctionDIs.count(mf.getFunction())) 717 return false; 718 if (!pImpl) 719 pImpl = new LDVImpl(this); 720 return static_cast<LDVImpl*>(pImpl)->runOnMachineFunction(mf); 721 } 722 723 void LiveDebugVariables::releaseMemory() { 724 if (pImpl) 725 static_cast<LDVImpl*>(pImpl)->clear(); 726 } 727 728 LiveDebugVariables::~LiveDebugVariables() { 729 if (pImpl) 730 delete static_cast<LDVImpl*>(pImpl); 731 } 732 733 //===----------------------------------------------------------------------===// 734 // Live Range Splitting 735 //===----------------------------------------------------------------------===// 736 737 bool 738 UserValue::splitLocation(unsigned OldLocNo, ArrayRef<unsigned> NewRegs, 739 LiveIntervals& LIS) { 740 DEBUG({ 741 dbgs() << "Splitting Loc" << OldLocNo << '\t'; 742 print(dbgs(), nullptr); 743 }); 744 bool DidChange = false; 745 LocMap::iterator LocMapI; 746 LocMapI.setMap(locInts); 747 for (unsigned i = 0; i != NewRegs.size(); ++i) { 748 LiveInterval *LI = &LIS.getInterval(NewRegs[i]); 749 if (LI->empty()) 750 continue; 751 752 // Don't allocate the new LocNo until it is needed. 753 unsigned NewLocNo = ~0u; 754 755 // Iterate over the overlaps between locInts and LI. 756 LocMapI.find(LI->beginIndex()); 757 if (!LocMapI.valid()) 758 continue; 759 LiveInterval::iterator LII = LI->advanceTo(LI->begin(), LocMapI.start()); 760 LiveInterval::iterator LIE = LI->end(); 761 while (LocMapI.valid() && LII != LIE) { 762 // At this point, we know that LocMapI.stop() > LII->start. 763 LII = LI->advanceTo(LII, LocMapI.start()); 764 if (LII == LIE) 765 break; 766 767 // Now LII->end > LocMapI.start(). Do we have an overlap? 768 if (LocMapI.value() == OldLocNo && LII->start < LocMapI.stop()) { 769 // Overlapping correct location. Allocate NewLocNo now. 770 if (NewLocNo == ~0u) { 771 MachineOperand MO = MachineOperand::CreateReg(LI->reg, false); 772 MO.setSubReg(locations[OldLocNo].getSubReg()); 773 NewLocNo = getLocationNo(MO); 774 DidChange = true; 775 } 776 777 SlotIndex LStart = LocMapI.start(); 778 SlotIndex LStop = LocMapI.stop(); 779 780 // Trim LocMapI down to the LII overlap. 781 if (LStart < LII->start) 782 LocMapI.setStartUnchecked(LII->start); 783 if (LStop > LII->end) 784 LocMapI.setStopUnchecked(LII->end); 785 786 // Change the value in the overlap. This may trigger coalescing. 787 LocMapI.setValue(NewLocNo); 788 789 // Re-insert any removed OldLocNo ranges. 790 if (LStart < LocMapI.start()) { 791 LocMapI.insert(LStart, LocMapI.start(), OldLocNo); 792 ++LocMapI; 793 assert(LocMapI.valid() && "Unexpected coalescing"); 794 } 795 if (LStop > LocMapI.stop()) { 796 ++LocMapI; 797 LocMapI.insert(LII->end, LStop, OldLocNo); 798 --LocMapI; 799 } 800 } 801 802 // Advance to the next overlap. 803 if (LII->end < LocMapI.stop()) { 804 if (++LII == LIE) 805 break; 806 LocMapI.advanceTo(LII->start); 807 } else { 808 ++LocMapI; 809 if (!LocMapI.valid()) 810 break; 811 LII = LI->advanceTo(LII, LocMapI.start()); 812 } 813 } 814 } 815 816 // Finally, remove any remaining OldLocNo intervals and OldLocNo itself. 817 locations.erase(locations.begin() + OldLocNo); 818 LocMapI.goToBegin(); 819 while (LocMapI.valid()) { 820 unsigned v = LocMapI.value(); 821 if (v == OldLocNo) { 822 DEBUG(dbgs() << "Erasing [" << LocMapI.start() << ';' 823 << LocMapI.stop() << ")\n"); 824 LocMapI.erase(); 825 } else { 826 if (v > OldLocNo) 827 LocMapI.setValueUnchecked(v-1); 828 ++LocMapI; 829 } 830 } 831 832 DEBUG({dbgs() << "Split result: \t"; print(dbgs(), nullptr);}); 833 return DidChange; 834 } 835 836 bool 837 UserValue::splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs, 838 LiveIntervals &LIS) { 839 bool DidChange = false; 840 // Split locations referring to OldReg. Iterate backwards so splitLocation can 841 // safely erase unused locations. 842 for (unsigned i = locations.size(); i ; --i) { 843 unsigned LocNo = i-1; 844 const MachineOperand *Loc = &locations[LocNo]; 845 if (!Loc->isReg() || Loc->getReg() != OldReg) 846 continue; 847 DidChange |= splitLocation(LocNo, NewRegs, LIS); 848 } 849 return DidChange; 850 } 851 852 void LDVImpl::splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs) { 853 bool DidChange = false; 854 for (UserValue *UV = lookupVirtReg(OldReg); UV; UV = UV->getNext()) 855 DidChange |= UV->splitRegister(OldReg, NewRegs, *LIS); 856 857 if (!DidChange) 858 return; 859 860 // Map all of the new virtual registers. 861 UserValue *UV = lookupVirtReg(OldReg); 862 for (unsigned i = 0; i != NewRegs.size(); ++i) 863 mapVirtReg(NewRegs[i], UV); 864 } 865 866 void LiveDebugVariables:: 867 splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs, LiveIntervals &LIS) { 868 if (pImpl) 869 static_cast<LDVImpl*>(pImpl)->splitRegister(OldReg, NewRegs); 870 } 871 872 void 873 UserValue::rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI) { 874 // Iterate over locations in reverse makes it easier to handle coalescing. 875 for (unsigned i = locations.size(); i ; --i) { 876 unsigned LocNo = i-1; 877 MachineOperand &Loc = locations[LocNo]; 878 // Only virtual registers are rewritten. 879 if (!Loc.isReg() || !Loc.getReg() || 880 !TargetRegisterInfo::isVirtualRegister(Loc.getReg())) 881 continue; 882 unsigned VirtReg = Loc.getReg(); 883 if (VRM.isAssignedReg(VirtReg) && 884 TargetRegisterInfo::isPhysicalRegister(VRM.getPhys(VirtReg))) { 885 // This can create a %noreg operand in rare cases when the sub-register 886 // index is no longer available. That means the user value is in a 887 // non-existent sub-register, and %noreg is exactly what we want. 888 Loc.substPhysReg(VRM.getPhys(VirtReg), TRI); 889 } else if (VRM.getStackSlot(VirtReg) != VirtRegMap::NO_STACK_SLOT) { 890 // FIXME: Translate SubIdx to a stackslot offset. 891 Loc = MachineOperand::CreateFI(VRM.getStackSlot(VirtReg)); 892 } else { 893 Loc.setReg(0); 894 Loc.setSubReg(0); 895 } 896 coalesceLocation(LocNo); 897 } 898 } 899 900 /// findInsertLocation - Find an iterator for inserting a DBG_VALUE 901 /// instruction. 902 static MachineBasicBlock::iterator 903 findInsertLocation(MachineBasicBlock *MBB, SlotIndex Idx, 904 LiveIntervals &LIS) { 905 SlotIndex Start = LIS.getMBBStartIdx(MBB); 906 Idx = Idx.getBaseIndex(); 907 908 // Try to find an insert location by going backwards from Idx. 909 MachineInstr *MI; 910 while (!(MI = LIS.getInstructionFromIndex(Idx))) { 911 // We've reached the beginning of MBB. 912 if (Idx == Start) { 913 MachineBasicBlock::iterator I = MBB->SkipPHIsAndLabels(MBB->begin()); 914 return I; 915 } 916 Idx = Idx.getPrevIndex(); 917 } 918 919 // Don't insert anything after the first terminator, though. 920 return MI->isTerminator() ? MBB->getFirstTerminator() : 921 std::next(MachineBasicBlock::iterator(MI)); 922 } 923 924 DebugLoc UserValue::findDebugLoc() { 925 DebugLoc D = dl; 926 dl = DebugLoc(); 927 return D; 928 } 929 void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx, 930 unsigned LocNo, 931 LiveIntervals &LIS, 932 const TargetInstrInfo &TII) { 933 MachineBasicBlock::iterator I = findInsertLocation(MBB, Idx, LIS); 934 MachineOperand &Loc = locations[LocNo]; 935 ++NumInsertedDebugValues; 936 937 if (Loc.isReg()) 938 BuildMI(*MBB, I, findDebugLoc(), TII.get(TargetOpcode::DBG_VALUE), 939 IsIndirect, Loc.getReg(), offset, variable); 940 else 941 BuildMI(*MBB, I, findDebugLoc(), TII.get(TargetOpcode::DBG_VALUE)) 942 .addOperand(Loc).addImm(offset).addMetadata(variable); 943 } 944 945 void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS, 946 const TargetInstrInfo &TII) { 947 MachineFunction::iterator MFEnd = VRM->getMachineFunction().end(); 948 949 for (LocMap::const_iterator I = locInts.begin(); I.valid();) { 950 SlotIndex Start = I.start(); 951 SlotIndex Stop = I.stop(); 952 unsigned LocNo = I.value(); 953 DEBUG(dbgs() << "\t[" << Start << ';' << Stop << "):" << LocNo); 954 MachineFunction::iterator MBB = LIS.getMBBFromIndex(Start); 955 SlotIndex MBBEnd = LIS.getMBBEndIdx(MBB); 956 957 DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd); 958 insertDebugValue(MBB, Start, LocNo, LIS, TII); 959 // This interval may span multiple basic blocks. 960 // Insert a DBG_VALUE into each one. 961 while(Stop > MBBEnd) { 962 // Move to the next block. 963 Start = MBBEnd; 964 if (++MBB == MFEnd) 965 break; 966 MBBEnd = LIS.getMBBEndIdx(MBB); 967 DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd); 968 insertDebugValue(MBB, Start, LocNo, LIS, TII); 969 } 970 DEBUG(dbgs() << '\n'); 971 if (MBB == MFEnd) 972 break; 973 974 ++I; 975 } 976 } 977 978 void LDVImpl::emitDebugValues(VirtRegMap *VRM) { 979 DEBUG(dbgs() << "********** EMITTING LIVE DEBUG VARIABLES **********\n"); 980 if (!MF) 981 return; 982 const TargetInstrInfo *TII = MF->getTarget().getInstrInfo(); 983 for (unsigned i = 0, e = userValues.size(); i != e; ++i) { 984 DEBUG(userValues[i]->print(dbgs(), &MF->getTarget())); 985 userValues[i]->rewriteLocations(*VRM, *TRI); 986 userValues[i]->emitDebugValues(VRM, *LIS, *TII); 987 } 988 EmitDone = true; 989 } 990 991 void LiveDebugVariables::emitDebugValues(VirtRegMap *VRM) { 992 if (pImpl) 993 static_cast<LDVImpl*>(pImpl)->emitDebugValues(VRM); 994 } 995 996 bool LiveDebugVariables::doInitialization(Module &M) { 997 FunctionDIs = makeSubprogramMap(M); 998 return Pass::doInitialization(M); 999 } 1000 1001 #ifndef NDEBUG 1002 void LiveDebugVariables::dump() { 1003 if (pImpl) 1004 static_cast<LDVImpl*>(pImpl)->print(dbgs()); 1005 } 1006 #endif 1007