1 //===- LiveDebugVariables.cpp - Tracking debug info variables -------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file implements the LiveDebugVariables analysis. 11 // 12 // Remove all DBG_VALUE instructions referencing virtual registers and replace 13 // them with a data structure tracking where live user variables are kept - in a 14 // virtual register or in a stack slot. 15 // 16 // Allow the data structure to be updated during register allocation when values 17 // are moved between registers and stack slots. Finally emit new DBG_VALUE 18 // instructions after register allocation is complete. 19 // 20 //===----------------------------------------------------------------------===// 21 22 #define DEBUG_TYPE "livedebug" 23 #include "LiveDebugVariables.h" 24 #include "VirtRegMap.h" 25 #include "llvm/Constants.h" 26 #include "llvm/Metadata.h" 27 #include "llvm/Value.h" 28 #include "llvm/ADT/IntervalMap.h" 29 #include "llvm/CodeGen/LiveIntervalAnalysis.h" 30 #include "llvm/CodeGen/MachineDominators.h" 31 #include "llvm/CodeGen/MachineFunction.h" 32 #include "llvm/CodeGen/MachineInstrBuilder.h" 33 #include "llvm/CodeGen/MachineRegisterInfo.h" 34 #include "llvm/CodeGen/Passes.h" 35 #include "llvm/Support/CommandLine.h" 36 #include "llvm/Support/Debug.h" 37 #include "llvm/Target/TargetInstrInfo.h" 38 #include "llvm/Target/TargetMachine.h" 39 #include "llvm/Target/TargetRegisterInfo.h" 40 41 using namespace llvm; 42 43 static cl::opt<bool> 44 EnableLDV("live-debug-variables", cl::init(true), 45 cl::desc("Enable the live debug variables pass"), cl::Hidden); 46 47 char LiveDebugVariables::ID = 0; 48 49 INITIALIZE_PASS_BEGIN(LiveDebugVariables, "livedebugvars", 50 "Debug Variable Analysis", false, false) 51 INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree) 52 INITIALIZE_PASS_DEPENDENCY(LiveIntervals) 53 INITIALIZE_PASS_END(LiveDebugVariables, "livedebugvars", 54 "Debug Variable Analysis", false, false) 55 56 void LiveDebugVariables::getAnalysisUsage(AnalysisUsage &AU) const { 57 AU.addRequired<MachineDominatorTree>(); 58 AU.addRequiredTransitive<LiveIntervals>(); 59 AU.setPreservesAll(); 60 MachineFunctionPass::getAnalysisUsage(AU); 61 } 62 63 LiveDebugVariables::LiveDebugVariables() : MachineFunctionPass(ID), pImpl(0) { 64 initializeLiveDebugVariablesPass(*PassRegistry::getPassRegistry()); 65 } 66 67 /// LocMap - Map of where a user value is live, and its location. 68 typedef IntervalMap<SlotIndex, unsigned, 4> LocMap; 69 70 /// UserValue - A user value is a part of a debug info user variable. 71 /// 72 /// A DBG_VALUE instruction notes that (a sub-register of) a virtual register 73 /// holds part of a user variable. The part is identified by a byte offset. 74 /// 75 /// UserValues are grouped into equivalence classes for easier searching. Two 76 /// user values are related if they refer to the same variable, or if they are 77 /// held by the same virtual register. The equivalence class is the transitive 78 /// closure of that relation. 79 namespace { 80 class LDVImpl; 81 class UserValue { 82 const MDNode *variable; ///< The debug info variable we are part of. 83 unsigned offset; ///< Byte offset into variable. 84 DebugLoc dl; ///< The debug location for the variable. This is 85 ///< used by dwarf writer to find lexical scope. 86 UserValue *leader; ///< Equivalence class leader. 87 UserValue *next; ///< Next value in equivalence class, or null. 88 89 /// Numbered locations referenced by locmap. 90 SmallVector<MachineOperand, 4> locations; 91 92 /// Map of slot indices where this value is live. 93 LocMap locInts; 94 95 /// coalesceLocation - After LocNo was changed, check if it has become 96 /// identical to another location, and coalesce them. This may cause LocNo or 97 /// a later location to be erased, but no earlier location will be erased. 98 void coalesceLocation(unsigned LocNo); 99 100 /// insertDebugValue - Insert a DBG_VALUE into MBB at Idx for LocNo. 101 void insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx, unsigned LocNo, 102 LiveIntervals &LIS, const TargetInstrInfo &TII); 103 104 public: 105 /// UserValue - Create a new UserValue. 106 UserValue(const MDNode *var, unsigned o, DebugLoc L, 107 LocMap::Allocator &alloc) 108 : variable(var), offset(o), dl(L), leader(this), next(0), locInts(alloc) 109 {} 110 111 /// getLeader - Get the leader of this value's equivalence class. 112 UserValue *getLeader() { 113 UserValue *l = leader; 114 while (l != l->leader) 115 l = l->leader; 116 return leader = l; 117 } 118 119 /// getNext - Return the next UserValue in the equivalence class. 120 UserValue *getNext() const { return next; } 121 122 /// match - Does this UserValue match the aprameters? 123 bool match(const MDNode *Var, unsigned Offset) const { 124 return Var == variable && Offset == offset; 125 } 126 127 /// merge - Merge equivalence classes. 128 static UserValue *merge(UserValue *L1, UserValue *L2) { 129 L2 = L2->getLeader(); 130 if (!L1) 131 return L2; 132 L1 = L1->getLeader(); 133 if (L1 == L2) 134 return L1; 135 // Splice L2 before L1's members. 136 UserValue *End = L2; 137 while (End->next) 138 End->leader = L1, End = End->next; 139 End->leader = L1; 140 End->next = L1->next; 141 L1->next = L2; 142 return L1; 143 } 144 145 /// getLocationNo - Return the location number that matches Loc. 146 unsigned getLocationNo(const MachineOperand &LocMO) { 147 if (LocMO.isReg()) { 148 if (LocMO.getReg() == 0) 149 return ~0u; 150 // For register locations we dont care about use/def and other flags. 151 for (unsigned i = 0, e = locations.size(); i != e; ++i) 152 if (locations[i].isReg() && 153 locations[i].getReg() == LocMO.getReg() && 154 locations[i].getSubReg() == LocMO.getSubReg()) 155 return i; 156 } else 157 for (unsigned i = 0, e = locations.size(); i != e; ++i) 158 if (LocMO.isIdenticalTo(locations[i])) 159 return i; 160 locations.push_back(LocMO); 161 // We are storing a MachineOperand outside a MachineInstr. 162 locations.back().clearParent(); 163 // Don't store def operands. 164 if (locations.back().isReg()) 165 locations.back().setIsUse(); 166 return locations.size() - 1; 167 } 168 169 /// mapVirtRegs - Ensure that all virtual register locations are mapped. 170 void mapVirtRegs(LDVImpl *LDV); 171 172 /// addDef - Add a definition point to this value. 173 void addDef(SlotIndex Idx, const MachineOperand &LocMO) { 174 // Add a singular (Idx,Idx) -> Loc mapping. 175 LocMap::iterator I = locInts.find(Idx); 176 if (!I.valid() || I.start() != Idx) 177 I.insert(Idx, Idx.getNextSlot(), getLocationNo(LocMO)); 178 } 179 180 /// extendDef - Extend the current definition as far as possible down the 181 /// dominator tree. Stop when meeting an existing def or when leaving the live 182 /// range of VNI. 183 /// End points where VNI is no longer live are added to Kills. 184 /// @param Idx Starting point for the definition. 185 /// @param LocNo Location number to propagate. 186 /// @param LI Restrict liveness to where LI has the value VNI. May be null. 187 /// @param VNI When LI is not null, this is the value to restrict to. 188 /// @param Kills Append end points of VNI's live range to Kills. 189 /// @param LIS Live intervals analysis. 190 /// @param MDT Dominator tree. 191 void extendDef(SlotIndex Idx, unsigned LocNo, 192 LiveInterval *LI, const VNInfo *VNI, 193 SmallVectorImpl<SlotIndex> *Kills, 194 LiveIntervals &LIS, MachineDominatorTree &MDT); 195 196 /// addDefsFromCopies - The value in LI/LocNo may be copies to other 197 /// registers. Determine if any of the copies are available at the kill 198 /// points, and add defs if possible. 199 /// @param LI Scan for copies of the value in LI->reg. 200 /// @param LocNo Location number of LI->reg. 201 /// @param Kills Points where the range of LocNo could be extended. 202 /// @param NewDefs Append (Idx, LocNo) of inserted defs here. 203 void addDefsFromCopies(LiveInterval *LI, unsigned LocNo, 204 const SmallVectorImpl<SlotIndex> &Kills, 205 SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs, 206 MachineRegisterInfo &MRI, 207 LiveIntervals &LIS); 208 209 /// computeIntervals - Compute the live intervals of all locations after 210 /// collecting all their def points. 211 void computeIntervals(MachineRegisterInfo &MRI, 212 LiveIntervals &LIS, MachineDominatorTree &MDT); 213 214 /// renameRegister - Update locations to rewrite OldReg as NewReg:SubIdx. 215 void renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx, 216 const TargetRegisterInfo *TRI); 217 218 /// rewriteLocations - Rewrite virtual register locations according to the 219 /// provided virtual register map. 220 void rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI); 221 222 /// emitDebugVariables - Recreate DBG_VALUE instruction from data structures. 223 void emitDebugValues(VirtRegMap *VRM, 224 LiveIntervals &LIS, const TargetInstrInfo &TRI); 225 226 /// findDebugLoc - Return DebugLoc used for this DBG_VALUE instruction. A 227 /// variable may have more than one corresponding DBG_VALUE instructions. 228 /// Only first one needs DebugLoc to identify variable's lexical scope 229 /// in source file. 230 DebugLoc findDebugLoc(); 231 void print(raw_ostream&, const TargetMachine*); 232 }; 233 } // namespace 234 235 /// LDVImpl - Implementation of the LiveDebugVariables pass. 236 namespace { 237 class LDVImpl { 238 LiveDebugVariables &pass; 239 LocMap::Allocator allocator; 240 MachineFunction *MF; 241 LiveIntervals *LIS; 242 MachineDominatorTree *MDT; 243 const TargetRegisterInfo *TRI; 244 245 /// userValues - All allocated UserValue instances. 246 SmallVector<UserValue*, 8> userValues; 247 248 /// Map virtual register to eq class leader. 249 typedef DenseMap<unsigned, UserValue*> VRMap; 250 VRMap virtRegToEqClass; 251 252 /// Map user variable to eq class leader. 253 typedef DenseMap<const MDNode *, UserValue*> UVMap; 254 UVMap userVarMap; 255 256 /// getUserValue - Find or create a UserValue. 257 UserValue *getUserValue(const MDNode *Var, unsigned Offset, DebugLoc DL); 258 259 /// lookupVirtReg - Find the EC leader for VirtReg or null. 260 UserValue *lookupVirtReg(unsigned VirtReg); 261 262 /// handleDebugValue - Add DBG_VALUE instruction to our maps. 263 /// @param MI DBG_VALUE instruction 264 /// @param Idx Last valid SLotIndex before instruction. 265 /// @return True if the DBG_VALUE instruction should be deleted. 266 bool handleDebugValue(MachineInstr *MI, SlotIndex Idx); 267 268 /// collectDebugValues - Collect and erase all DBG_VALUE instructions, adding 269 /// a UserValue def for each instruction. 270 /// @param mf MachineFunction to be scanned. 271 /// @return True if any debug values were found. 272 bool collectDebugValues(MachineFunction &mf); 273 274 /// computeIntervals - Compute the live intervals of all user values after 275 /// collecting all their def points. 276 void computeIntervals(); 277 278 public: 279 LDVImpl(LiveDebugVariables *ps) : pass(*ps) {} 280 bool runOnMachineFunction(MachineFunction &mf); 281 282 /// clear - Relase all memory. 283 void clear() { 284 DeleteContainerPointers(userValues); 285 userValues.clear(); 286 virtRegToEqClass.clear(); 287 userVarMap.clear(); 288 } 289 290 /// mapVirtReg - Map virtual register to an equivalence class. 291 void mapVirtReg(unsigned VirtReg, UserValue *EC); 292 293 /// renameRegister - Replace all references to OldReg with NewReg:SubIdx. 294 void renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx); 295 296 /// emitDebugVariables - Recreate DBG_VALUE instruction from data structures. 297 void emitDebugValues(VirtRegMap *VRM); 298 299 void print(raw_ostream&); 300 }; 301 } // namespace 302 303 void UserValue::print(raw_ostream &OS, const TargetMachine *TM) { 304 if (const MDString *MDS = dyn_cast<MDString>(variable->getOperand(2))) 305 OS << "!\"" << MDS->getString() << "\"\t"; 306 if (offset) 307 OS << '+' << offset; 308 for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) { 309 OS << " [" << I.start() << ';' << I.stop() << "):"; 310 if (I.value() == ~0u) 311 OS << "undef"; 312 else 313 OS << I.value(); 314 } 315 for (unsigned i = 0, e = locations.size(); i != e; ++i) { 316 OS << " Loc" << i << '='; 317 locations[i].print(OS, TM); 318 } 319 OS << '\n'; 320 } 321 322 void LDVImpl::print(raw_ostream &OS) { 323 OS << "********** DEBUG VARIABLES **********\n"; 324 for (unsigned i = 0, e = userValues.size(); i != e; ++i) 325 userValues[i]->print(OS, &MF->getTarget()); 326 } 327 328 void UserValue::coalesceLocation(unsigned LocNo) { 329 unsigned KeepLoc = 0; 330 for (unsigned e = locations.size(); KeepLoc != e; ++KeepLoc) { 331 if (KeepLoc == LocNo) 332 continue; 333 if (locations[KeepLoc].isIdenticalTo(locations[LocNo])) 334 break; 335 } 336 // No matches. 337 if (KeepLoc == locations.size()) 338 return; 339 340 // Keep the smaller location, erase the larger one. 341 unsigned EraseLoc = LocNo; 342 if (KeepLoc > EraseLoc) 343 std::swap(KeepLoc, EraseLoc); 344 locations.erase(locations.begin() + EraseLoc); 345 346 // Rewrite values. 347 for (LocMap::iterator I = locInts.begin(); I.valid(); ++I) { 348 unsigned v = I.value(); 349 if (v == EraseLoc) 350 I.setValue(KeepLoc); // Coalesce when possible. 351 else if (v > EraseLoc) 352 I.setValueUnchecked(v-1); // Avoid coalescing with untransformed values. 353 } 354 } 355 356 void UserValue::mapVirtRegs(LDVImpl *LDV) { 357 for (unsigned i = 0, e = locations.size(); i != e; ++i) 358 if (locations[i].isReg() && 359 TargetRegisterInfo::isVirtualRegister(locations[i].getReg())) 360 LDV->mapVirtReg(locations[i].getReg(), this); 361 } 362 363 UserValue *LDVImpl::getUserValue(const MDNode *Var, unsigned Offset, 364 DebugLoc DL) { 365 UserValue *&Leader = userVarMap[Var]; 366 if (Leader) { 367 UserValue *UV = Leader->getLeader(); 368 Leader = UV; 369 for (; UV; UV = UV->getNext()) 370 if (UV->match(Var, Offset)) 371 return UV; 372 } 373 374 UserValue *UV = new UserValue(Var, Offset, DL, allocator); 375 userValues.push_back(UV); 376 Leader = UserValue::merge(Leader, UV); 377 return UV; 378 } 379 380 void LDVImpl::mapVirtReg(unsigned VirtReg, UserValue *EC) { 381 assert(TargetRegisterInfo::isVirtualRegister(VirtReg) && "Only map VirtRegs"); 382 UserValue *&Leader = virtRegToEqClass[VirtReg]; 383 Leader = UserValue::merge(Leader, EC); 384 } 385 386 UserValue *LDVImpl::lookupVirtReg(unsigned VirtReg) { 387 if (UserValue *UV = virtRegToEqClass.lookup(VirtReg)) 388 return UV->getLeader(); 389 return 0; 390 } 391 392 bool LDVImpl::handleDebugValue(MachineInstr *MI, SlotIndex Idx) { 393 // DBG_VALUE loc, offset, variable 394 if (MI->getNumOperands() != 3 || 395 !MI->getOperand(1).isImm() || !MI->getOperand(2).isMetadata()) { 396 DEBUG(dbgs() << "Can't handle " << *MI); 397 return false; 398 } 399 400 // Get or create the UserValue for (variable,offset). 401 unsigned Offset = MI->getOperand(1).getImm(); 402 const MDNode *Var = MI->getOperand(2).getMetadata(); 403 UserValue *UV = getUserValue(Var, Offset, MI->getDebugLoc()); 404 UV->addDef(Idx, MI->getOperand(0)); 405 return true; 406 } 407 408 bool LDVImpl::collectDebugValues(MachineFunction &mf) { 409 bool Changed = false; 410 for (MachineFunction::iterator MFI = mf.begin(), MFE = mf.end(); MFI != MFE; 411 ++MFI) { 412 MachineBasicBlock *MBB = MFI; 413 for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end(); 414 MBBI != MBBE;) { 415 if (!MBBI->isDebugValue()) { 416 ++MBBI; 417 continue; 418 } 419 // DBG_VALUE has no slot index, use the previous instruction instead. 420 SlotIndex Idx = MBBI == MBB->begin() ? 421 LIS->getMBBStartIdx(MBB) : 422 LIS->getInstructionIndex(llvm::prior(MBBI)).getDefIndex(); 423 // Handle consecutive DBG_VALUE instructions with the same slot index. 424 do { 425 if (handleDebugValue(MBBI, Idx)) { 426 MBBI = MBB->erase(MBBI); 427 Changed = true; 428 } else 429 ++MBBI; 430 } while (MBBI != MBBE && MBBI->isDebugValue()); 431 } 432 } 433 return Changed; 434 } 435 436 void UserValue::extendDef(SlotIndex Idx, unsigned LocNo, 437 LiveInterval *LI, const VNInfo *VNI, 438 SmallVectorImpl<SlotIndex> *Kills, 439 LiveIntervals &LIS, MachineDominatorTree &MDT) { 440 SmallVector<SlotIndex, 16> Todo; 441 Todo.push_back(Idx); 442 443 do { 444 SlotIndex Start = Todo.pop_back_val(); 445 MachineBasicBlock *MBB = LIS.getMBBFromIndex(Start); 446 SlotIndex Stop = LIS.getMBBEndIdx(MBB); 447 LocMap::iterator I = locInts.find(Start); 448 449 // Limit to VNI's live range. 450 bool ToEnd = true; 451 if (LI && VNI) { 452 LiveRange *Range = LI->getLiveRangeContaining(Start); 453 if (!Range || Range->valno != VNI) { 454 if (Kills) 455 Kills->push_back(Start); 456 continue; 457 } 458 if (Range->end < Stop) 459 Stop = Range->end, ToEnd = false; 460 } 461 462 // There could already be a short def at Start. 463 if (I.valid() && I.start() <= Start) { 464 // Stop when meeting a different location or an already extended interval. 465 Start = Start.getNextSlot(); 466 if (I.value() != LocNo || I.stop() != Start) 467 continue; 468 // This is a one-slot placeholder. Just skip it. 469 ++I; 470 } 471 472 // Limited by the next def. 473 if (I.valid() && I.start() < Stop) 474 Stop = I.start(), ToEnd = false; 475 // Limited by VNI's live range. 476 else if (!ToEnd && Kills) 477 Kills->push_back(Stop); 478 479 if (Start >= Stop) 480 continue; 481 482 I.insert(Start, Stop, LocNo); 483 484 // If we extended to the MBB end, propagate down the dominator tree. 485 if (!ToEnd) 486 continue; 487 const std::vector<MachineDomTreeNode*> &Children = 488 MDT.getNode(MBB)->getChildren(); 489 for (unsigned i = 0, e = Children.size(); i != e; ++i) 490 Todo.push_back(LIS.getMBBStartIdx(Children[i]->getBlock())); 491 } while (!Todo.empty()); 492 } 493 494 void 495 UserValue::addDefsFromCopies(LiveInterval *LI, unsigned LocNo, 496 const SmallVectorImpl<SlotIndex> &Kills, 497 SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs, 498 MachineRegisterInfo &MRI, LiveIntervals &LIS) { 499 if (Kills.empty()) 500 return; 501 // Don't track copies from physregs, there are too many uses. 502 if (!TargetRegisterInfo::isVirtualRegister(LI->reg)) 503 return; 504 505 // Collect all the (vreg, valno) pairs that are copies of LI. 506 SmallVector<std::pair<LiveInterval*, const VNInfo*>, 8> CopyValues; 507 for (MachineRegisterInfo::use_nodbg_iterator 508 UI = MRI.use_nodbg_begin(LI->reg), 509 UE = MRI.use_nodbg_end(); UI != UE; ++UI) { 510 // Copies of the full value. 511 if (UI.getOperand().getSubReg() || !UI->isCopy()) 512 continue; 513 MachineInstr *MI = &*UI; 514 unsigned DstReg = MI->getOperand(0).getReg(); 515 516 // Don't follow copies to physregs. These are usually setting up call 517 // arguments, and the argument registers are always call clobbered. We are 518 // better off in the source register which could be a callee-saved register, 519 // or it could be spilled. 520 if (!TargetRegisterInfo::isVirtualRegister(DstReg)) 521 continue; 522 523 // Is LocNo extended to reach this copy? If not, another def may be blocking 524 // it, or we are looking at a wrong value of LI. 525 SlotIndex Idx = LIS.getInstructionIndex(MI); 526 LocMap::iterator I = locInts.find(Idx.getUseIndex()); 527 if (!I.valid() || I.value() != LocNo) 528 continue; 529 530 if (!LIS.hasInterval(DstReg)) 531 continue; 532 LiveInterval *DstLI = &LIS.getInterval(DstReg); 533 const VNInfo *DstVNI = DstLI->getVNInfoAt(Idx.getDefIndex()); 534 assert(DstVNI && DstVNI->def == Idx.getDefIndex() && "Bad copy value"); 535 CopyValues.push_back(std::make_pair(DstLI, DstVNI)); 536 } 537 538 if (CopyValues.empty()) 539 return; 540 541 DEBUG(dbgs() << "Got " << CopyValues.size() << " copies of " << *LI << '\n'); 542 543 // Try to add defs of the copied values for each kill point. 544 for (unsigned i = 0, e = Kills.size(); i != e; ++i) { 545 SlotIndex Idx = Kills[i]; 546 for (unsigned j = 0, e = CopyValues.size(); j != e; ++j) { 547 LiveInterval *DstLI = CopyValues[j].first; 548 const VNInfo *DstVNI = CopyValues[j].second; 549 if (DstLI->getVNInfoAt(Idx) != DstVNI) 550 continue; 551 // Check that there isn't already a def at Idx 552 LocMap::iterator I = locInts.find(Idx); 553 if (I.valid() && I.start() <= Idx) 554 continue; 555 DEBUG(dbgs() << "Kill at " << Idx << " covered by valno #" 556 << DstVNI->id << " in " << *DstLI << '\n'); 557 MachineInstr *CopyMI = LIS.getInstructionFromIndex(DstVNI->def); 558 assert(CopyMI && CopyMI->isCopy() && "Bad copy value"); 559 unsigned LocNo = getLocationNo(CopyMI->getOperand(0)); 560 I.insert(Idx, Idx.getNextSlot(), LocNo); 561 NewDefs.push_back(std::make_pair(Idx, LocNo)); 562 break; 563 } 564 } 565 } 566 567 void 568 UserValue::computeIntervals(MachineRegisterInfo &MRI, 569 LiveIntervals &LIS, 570 MachineDominatorTree &MDT) { 571 SmallVector<std::pair<SlotIndex, unsigned>, 16> Defs; 572 573 // Collect all defs to be extended (Skipping undefs). 574 for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) 575 if (I.value() != ~0u) 576 Defs.push_back(std::make_pair(I.start(), I.value())); 577 578 // Extend all defs, and possibly add new ones along the way. 579 for (unsigned i = 0; i != Defs.size(); ++i) { 580 SlotIndex Idx = Defs[i].first; 581 unsigned LocNo = Defs[i].second; 582 const MachineOperand &Loc = locations[LocNo]; 583 584 // Register locations are constrained to where the register value is live. 585 if (Loc.isReg() && LIS.hasInterval(Loc.getReg())) { 586 LiveInterval *LI = &LIS.getInterval(Loc.getReg()); 587 const VNInfo *VNI = LI->getVNInfoAt(Idx); 588 SmallVector<SlotIndex, 16> Kills; 589 extendDef(Idx, LocNo, LI, VNI, &Kills, LIS, MDT); 590 addDefsFromCopies(LI, LocNo, Kills, Defs, MRI, LIS); 591 } else 592 extendDef(Idx, LocNo, 0, 0, 0, LIS, MDT); 593 } 594 595 // Finally, erase all the undefs. 596 for (LocMap::iterator I = locInts.begin(); I.valid();) 597 if (I.value() == ~0u) 598 I.erase(); 599 else 600 ++I; 601 } 602 603 void LDVImpl::computeIntervals() { 604 for (unsigned i = 0, e = userValues.size(); i != e; ++i) { 605 userValues[i]->computeIntervals(MF->getRegInfo(), *LIS, *MDT); 606 userValues[i]->mapVirtRegs(this); 607 } 608 } 609 610 bool LDVImpl::runOnMachineFunction(MachineFunction &mf) { 611 MF = &mf; 612 LIS = &pass.getAnalysis<LiveIntervals>(); 613 MDT = &pass.getAnalysis<MachineDominatorTree>(); 614 TRI = mf.getTarget().getRegisterInfo(); 615 clear(); 616 DEBUG(dbgs() << "********** COMPUTING LIVE DEBUG VARIABLES: " 617 << ((Value*)mf.getFunction())->getName() 618 << " **********\n"); 619 620 bool Changed = collectDebugValues(mf); 621 computeIntervals(); 622 DEBUG(print(dbgs())); 623 return Changed; 624 } 625 626 bool LiveDebugVariables::runOnMachineFunction(MachineFunction &mf) { 627 if (!EnableLDV) 628 return false; 629 if (!pImpl) 630 pImpl = new LDVImpl(this); 631 return static_cast<LDVImpl*>(pImpl)->runOnMachineFunction(mf); 632 } 633 634 void LiveDebugVariables::releaseMemory() { 635 if (pImpl) 636 static_cast<LDVImpl*>(pImpl)->clear(); 637 } 638 639 LiveDebugVariables::~LiveDebugVariables() { 640 if (pImpl) 641 delete static_cast<LDVImpl*>(pImpl); 642 } 643 644 void UserValue:: 645 renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx, 646 const TargetRegisterInfo *TRI) { 647 for (unsigned i = locations.size(); i; --i) { 648 unsigned LocNo = i - 1; 649 MachineOperand &Loc = locations[LocNo]; 650 if (!Loc.isReg() || Loc.getReg() != OldReg) 651 continue; 652 if (TargetRegisterInfo::isPhysicalRegister(NewReg)) 653 Loc.substPhysReg(NewReg, *TRI); 654 else 655 Loc.substVirtReg(NewReg, SubIdx, *TRI); 656 coalesceLocation(LocNo); 657 } 658 } 659 660 void LDVImpl:: 661 renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx) { 662 UserValue *UV = lookupVirtReg(OldReg); 663 if (!UV) 664 return; 665 666 if (TargetRegisterInfo::isVirtualRegister(NewReg)) 667 mapVirtReg(NewReg, UV); 668 virtRegToEqClass.erase(OldReg); 669 670 do { 671 UV->renameRegister(OldReg, NewReg, SubIdx, TRI); 672 UV = UV->getNext(); 673 } while (UV); 674 } 675 676 void LiveDebugVariables:: 677 renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx) { 678 if (pImpl) 679 static_cast<LDVImpl*>(pImpl)->renameRegister(OldReg, NewReg, SubIdx); 680 } 681 682 void 683 UserValue::rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI) { 684 // Iterate over locations in reverse makes it easier to handle coalescing. 685 for (unsigned i = locations.size(); i ; --i) { 686 unsigned LocNo = i-1; 687 MachineOperand &Loc = locations[LocNo]; 688 // Only virtual registers are rewritten. 689 if (!Loc.isReg() || !Loc.getReg() || 690 !TargetRegisterInfo::isVirtualRegister(Loc.getReg())) 691 continue; 692 unsigned VirtReg = Loc.getReg(); 693 if (VRM.isAssignedReg(VirtReg) && 694 TargetRegisterInfo::isPhysicalRegister(VRM.getPhys(VirtReg))) { 695 Loc.substPhysReg(VRM.getPhys(VirtReg), TRI); 696 } else if (VRM.getStackSlot(VirtReg) != VirtRegMap::NO_STACK_SLOT && 697 VRM.isSpillSlotUsed(VRM.getStackSlot(VirtReg))) { 698 // FIXME: Translate SubIdx to a stackslot offset. 699 Loc = MachineOperand::CreateFI(VRM.getStackSlot(VirtReg)); 700 } else { 701 Loc.setReg(0); 702 Loc.setSubReg(0); 703 } 704 coalesceLocation(LocNo); 705 } 706 } 707 708 /// findInsertLocation - Find an iterator for inserting a DBG_VALUE 709 /// instruction. 710 static MachineBasicBlock::iterator 711 findInsertLocation(MachineBasicBlock *MBB, SlotIndex Idx, 712 LiveIntervals &LIS) { 713 SlotIndex Start = LIS.getMBBStartIdx(MBB); 714 Idx = Idx.getBaseIndex(); 715 716 // Try to find an insert location by going backwards from Idx. 717 MachineInstr *MI; 718 while (!(MI = LIS.getInstructionFromIndex(Idx))) { 719 // We've reached the beginning of MBB. 720 if (Idx == Start) { 721 MachineBasicBlock::iterator I = MBB->SkipPHIsAndLabels(MBB->begin()); 722 return I; 723 } 724 Idx = Idx.getPrevIndex(); 725 } 726 727 // Don't insert anything after the first terminator, though. 728 return MI->getDesc().isTerminator() ? MBB->getFirstTerminator() : 729 llvm::next(MachineBasicBlock::iterator(MI)); 730 } 731 732 DebugLoc UserValue::findDebugLoc() { 733 DebugLoc D = dl; 734 dl = DebugLoc(); 735 return D; 736 } 737 void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx, 738 unsigned LocNo, 739 LiveIntervals &LIS, 740 const TargetInstrInfo &TII) { 741 MachineBasicBlock::iterator I = findInsertLocation(MBB, Idx, LIS); 742 MachineOperand &Loc = locations[LocNo]; 743 744 // Frame index locations may require a target callback. 745 if (Loc.isFI()) { 746 MachineInstr *MI = TII.emitFrameIndexDebugValue(*MBB->getParent(), 747 Loc.getIndex(), offset, variable, 748 findDebugLoc()); 749 if (MI) { 750 MBB->insert(I, MI); 751 return; 752 } 753 } 754 // This is not a frame index, or the target is happy with a standard FI. 755 BuildMI(*MBB, I, findDebugLoc(), TII.get(TargetOpcode::DBG_VALUE)) 756 .addOperand(Loc).addImm(offset).addMetadata(variable); 757 } 758 759 void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS, 760 const TargetInstrInfo &TII) { 761 MachineFunction::iterator MFEnd = VRM->getMachineFunction().end(); 762 763 for (LocMap::const_iterator I = locInts.begin(); I.valid();) { 764 SlotIndex Start = I.start(); 765 SlotIndex Stop = I.stop(); 766 unsigned LocNo = I.value(); 767 DEBUG(dbgs() << "\t[" << Start << ';' << Stop << "):" << LocNo); 768 MachineFunction::iterator MBB = LIS.getMBBFromIndex(Start); 769 SlotIndex MBBEnd = LIS.getMBBEndIdx(MBB); 770 771 DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd); 772 insertDebugValue(MBB, Start, LocNo, LIS, TII); 773 774 // This interval may span multiple basic blocks. 775 // Insert a DBG_VALUE into each one. 776 while(Stop > MBBEnd) { 777 // Move to the next block. 778 Start = MBBEnd; 779 if (++MBB == MFEnd) 780 break; 781 MBBEnd = LIS.getMBBEndIdx(MBB); 782 DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd); 783 insertDebugValue(MBB, Start, LocNo, LIS, TII); 784 } 785 DEBUG(dbgs() << '\n'); 786 if (MBB == MFEnd) 787 break; 788 789 ++I; 790 } 791 } 792 793 void LDVImpl::emitDebugValues(VirtRegMap *VRM) { 794 DEBUG(dbgs() << "********** EMITTING LIVE DEBUG VARIABLES **********\n"); 795 const TargetInstrInfo *TII = MF->getTarget().getInstrInfo(); 796 for (unsigned i = 0, e = userValues.size(); i != e; ++i) { 797 userValues[i]->rewriteLocations(*VRM, *TRI); 798 userValues[i]->emitDebugValues(VRM, *LIS, *TII); 799 } 800 } 801 802 void LiveDebugVariables::emitDebugValues(VirtRegMap *VRM) { 803 if (pImpl) 804 static_cast<LDVImpl*>(pImpl)->emitDebugValues(VRM); 805 } 806 807 808 #ifndef NDEBUG 809 void LiveDebugVariables::dump() { 810 if (pImpl) 811 static_cast<LDVImpl*>(pImpl)->print(dbgs()); 812 } 813 #endif 814 815