CriticalAntiDepBreaker.cpp revision 2f6036058529a862f1800b99e0b03f7506d4eb53
1//===----- CriticalAntiDepBreaker.cpp - Anti-dep breaker -------- ---------===// 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 CriticalAntiDepBreaker class, which 11// implements register anti-dependence breaking along a blocks 12// critical path during post-RA scheduler. 13// 14//===----------------------------------------------------------------------===// 15 16#define DEBUG_TYPE "post-RA-sched" 17#include "CriticalAntiDepBreaker.h" 18#include "llvm/CodeGen/MachineBasicBlock.h" 19#include "llvm/CodeGen/MachineFrameInfo.h" 20#include "llvm/Target/TargetMachine.h" 21#include "llvm/Target/TargetInstrInfo.h" 22#include "llvm/Target/TargetRegisterInfo.h" 23#include "llvm/Support/Debug.h" 24#include "llvm/Support/ErrorHandling.h" 25#include "llvm/Support/raw_ostream.h" 26 27using namespace llvm; 28 29CriticalAntiDepBreaker:: 30CriticalAntiDepBreaker(MachineFunction& MFi) : 31 AntiDepBreaker(), MF(MFi), 32 MRI(MF.getRegInfo()), 33 TII(MF.getTarget().getInstrInfo()), 34 TRI(MF.getTarget().getRegisterInfo()), 35 AllocatableSet(TRI->getAllocatableSet(MF)), 36 Classes(TRI->getNumRegs(), static_cast<const TargetRegisterClass *>(0)), 37 KillIndices(TRI->getNumRegs(), 0), 38 DefIndices(TRI->getNumRegs(), 0) {} 39 40CriticalAntiDepBreaker::~CriticalAntiDepBreaker() { 41} 42 43void CriticalAntiDepBreaker::StartBlock(MachineBasicBlock *BB) { 44 const unsigned BBSize = BB->size(); 45 for (unsigned i = 0, e = TRI->getNumRegs(); i != e; ++i) { 46 // Clear out the register class data. 47 Classes[i] = static_cast<const TargetRegisterClass *>(0); 48 49 // Initialize the indices to indicate that no registers are live. 50 KillIndices[i] = ~0u; 51 DefIndices[i] = BBSize; 52 } 53 54 // Clear "do not change" set. 55 KeepRegs.clear(); 56 57 bool IsReturnBlock = (!BB->empty() && BB->back().getDesc().isReturn()); 58 59 // Determine the live-out physregs for this block. 60 if (IsReturnBlock) { 61 // In a return block, examine the function live-out regs. 62 for (MachineRegisterInfo::liveout_iterator I = MRI.liveout_begin(), 63 E = MRI.liveout_end(); I != E; ++I) { 64 unsigned Reg = *I; 65 Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1); 66 KillIndices[Reg] = BB->size(); 67 DefIndices[Reg] = ~0u; 68 69 // Repeat, for all aliases. 70 for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) { 71 unsigned AliasReg = *Alias; 72 Classes[AliasReg] = reinterpret_cast<TargetRegisterClass *>(-1); 73 KillIndices[AliasReg] = BB->size(); 74 DefIndices[AliasReg] = ~0u; 75 } 76 } 77 } 78 79 // In a non-return block, examine the live-in regs of all successors. 80 // Note a return block can have successors if the return instruction is 81 // predicated. 82 for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(), 83 SE = BB->succ_end(); SI != SE; ++SI) 84 for (MachineBasicBlock::livein_iterator I = (*SI)->livein_begin(), 85 E = (*SI)->livein_end(); I != E; ++I) { 86 unsigned Reg = *I; 87 Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1); 88 KillIndices[Reg] = BB->size(); 89 DefIndices[Reg] = ~0u; 90 91 // Repeat, for all aliases. 92 for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) { 93 unsigned AliasReg = *Alias; 94 Classes[AliasReg] = reinterpret_cast<TargetRegisterClass *>(-1); 95 KillIndices[AliasReg] = BB->size(); 96 DefIndices[AliasReg] = ~0u; 97 } 98 } 99 100 // Mark live-out callee-saved registers. In a return block this is 101 // all callee-saved registers. In non-return this is any 102 // callee-saved register that is not saved in the prolog. 103 const MachineFrameInfo *MFI = MF.getFrameInfo(); 104 BitVector Pristine = MFI->getPristineRegs(BB); 105 for (const unsigned *I = TRI->getCalleeSavedRegs(); *I; ++I) { 106 unsigned Reg = *I; 107 if (!IsReturnBlock && !Pristine.test(Reg)) continue; 108 Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1); 109 KillIndices[Reg] = BB->size(); 110 DefIndices[Reg] = ~0u; 111 112 // Repeat, for all aliases. 113 for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) { 114 unsigned AliasReg = *Alias; 115 Classes[AliasReg] = reinterpret_cast<TargetRegisterClass *>(-1); 116 KillIndices[AliasReg] = BB->size(); 117 DefIndices[AliasReg] = ~0u; 118 } 119 } 120} 121 122void CriticalAntiDepBreaker::FinishBlock() { 123 RegRefs.clear(); 124 KeepRegs.clear(); 125} 126 127void CriticalAntiDepBreaker::Observe(MachineInstr *MI, unsigned Count, 128 unsigned InsertPosIndex) { 129 if (MI->isDebugValue()) 130 return; 131 assert(Count < InsertPosIndex && "Instruction index out of expected range!"); 132 133 // Any register which was defined within the previous scheduling region 134 // may have been rescheduled and its lifetime may overlap with registers 135 // in ways not reflected in our current liveness state. For each such 136 // register, adjust the liveness state to be conservatively correct. 137 for (unsigned Reg = 0; Reg != TRI->getNumRegs(); ++Reg) 138 if (DefIndices[Reg] < InsertPosIndex && DefIndices[Reg] >= Count) { 139 assert(KillIndices[Reg] == ~0u && "Clobbered register is live!"); 140 141 // Mark this register to be non-renamable. 142 Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1); 143 144 // Move the def index to the end of the previous region, to reflect 145 // that the def could theoretically have been scheduled at the end. 146 DefIndices[Reg] = InsertPosIndex; 147 } 148 149 PrescanInstruction(MI); 150 ScanInstruction(MI, Count); 151} 152 153/// CriticalPathStep - Return the next SUnit after SU on the bottom-up 154/// critical path. 155static const SDep *CriticalPathStep(const SUnit *SU) { 156 const SDep *Next = 0; 157 unsigned NextDepth = 0; 158 // Find the predecessor edge with the greatest depth. 159 for (SUnit::const_pred_iterator P = SU->Preds.begin(), PE = SU->Preds.end(); 160 P != PE; ++P) { 161 const SUnit *PredSU = P->getSUnit(); 162 unsigned PredLatency = P->getLatency(); 163 unsigned PredTotalLatency = PredSU->getDepth() + PredLatency; 164 // In the case of a latency tie, prefer an anti-dependency edge over 165 // other types of edges. 166 if (NextDepth < PredTotalLatency || 167 (NextDepth == PredTotalLatency && P->getKind() == SDep::Anti)) { 168 NextDepth = PredTotalLatency; 169 Next = &*P; 170 } 171 } 172 return Next; 173} 174 175void CriticalAntiDepBreaker::PrescanInstruction(MachineInstr *MI) { 176 // It's not safe to change register allocation for source operands of 177 // that have special allocation requirements. Also assume all registers 178 // used in a call must not be changed (ABI). 179 // FIXME: The issue with predicated instruction is more complex. We are being 180 // conservatively here because the kill markers cannot be trusted after 181 // if-conversion: 182 // %R6<def> = LDR %SP, %reg0, 92, pred:14, pred:%reg0; mem:LD4[FixedStack14] 183 // ... 184 // STR %R0, %R6<kill>, %reg0, 0, pred:0, pred:%CPSR; mem:ST4[%395] 185 // %R6<def> = LDR %SP, %reg0, 100, pred:0, pred:%CPSR; mem:LD4[FixedStack12] 186 // STR %R0, %R6<kill>, %reg0, 0, pred:14, pred:%reg0; mem:ST4[%396](align=8) 187 // 188 // The first R6 kill is not really a kill since it's killed by a predicated 189 // instruction which may not be executed. The second R6 def may or may not 190 // re-define R6 so it's not safe to change it since the last R6 use cannot be 191 // changed. 192 bool Special = MI->getDesc().isCall() || 193 MI->getDesc().hasExtraSrcRegAllocReq() || 194 TII->isPredicated(MI); 195 196 // Scan the register operands for this instruction and update 197 // Classes and RegRefs. 198 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { 199 MachineOperand &MO = MI->getOperand(i); 200 if (!MO.isReg()) continue; 201 unsigned Reg = MO.getReg(); 202 if (Reg == 0) continue; 203 const TargetRegisterClass *NewRC = 0; 204 205 if (i < MI->getDesc().getNumOperands()) 206 NewRC = MI->getDesc().OpInfo[i].getRegClass(TRI); 207 208 // For now, only allow the register to be changed if its register 209 // class is consistent across all uses. 210 if (!Classes[Reg] && NewRC) 211 Classes[Reg] = NewRC; 212 else if (!NewRC || Classes[Reg] != NewRC) 213 Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1); 214 215 // Now check for aliases. 216 for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) { 217 // If an alias of the reg is used during the live range, give up. 218 // Note that this allows us to skip checking if AntiDepReg 219 // overlaps with any of the aliases, among other things. 220 unsigned AliasReg = *Alias; 221 if (Classes[AliasReg]) { 222 Classes[AliasReg] = reinterpret_cast<TargetRegisterClass *>(-1); 223 Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1); 224 } 225 } 226 227 // If we're still willing to consider this register, note the reference. 228 if (Classes[Reg] != reinterpret_cast<TargetRegisterClass *>(-1)) 229 RegRefs.insert(std::make_pair(Reg, &MO)); 230 231 if (MO.isUse() && Special) { 232 if (KeepRegs.insert(Reg)) { 233 for (const unsigned *Subreg = TRI->getSubRegisters(Reg); 234 *Subreg; ++Subreg) 235 KeepRegs.insert(*Subreg); 236 } 237 } 238 } 239} 240 241void CriticalAntiDepBreaker::ScanInstruction(MachineInstr *MI, 242 unsigned Count) { 243 // Update liveness. 244 // Proceding upwards, registers that are defed but not used in this 245 // instruction are now dead. 246 247 if (!TII->isPredicated(MI)) { 248 // Predicated defs are modeled as read + write, i.e. similar to two 249 // address updates. 250 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { 251 MachineOperand &MO = MI->getOperand(i); 252 if (!MO.isReg()) continue; 253 unsigned Reg = MO.getReg(); 254 if (Reg == 0) continue; 255 if (!MO.isDef()) continue; 256 // Ignore two-addr defs. 257 if (MI->isRegTiedToUseOperand(i)) continue; 258 259 DefIndices[Reg] = Count; 260 KillIndices[Reg] = ~0u; 261 assert(((KillIndices[Reg] == ~0u) != 262 (DefIndices[Reg] == ~0u)) && 263 "Kill and Def maps aren't consistent for Reg!"); 264 KeepRegs.erase(Reg); 265 Classes[Reg] = 0; 266 RegRefs.erase(Reg); 267 // Repeat, for all subregs. 268 for (const unsigned *Subreg = TRI->getSubRegisters(Reg); 269 *Subreg; ++Subreg) { 270 unsigned SubregReg = *Subreg; 271 DefIndices[SubregReg] = Count; 272 KillIndices[SubregReg] = ~0u; 273 KeepRegs.erase(SubregReg); 274 Classes[SubregReg] = 0; 275 RegRefs.erase(SubregReg); 276 } 277 // Conservatively mark super-registers as unusable. 278 for (const unsigned *Super = TRI->getSuperRegisters(Reg); 279 *Super; ++Super) { 280 unsigned SuperReg = *Super; 281 Classes[SuperReg] = reinterpret_cast<TargetRegisterClass *>(-1); 282 } 283 } 284 } 285 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { 286 MachineOperand &MO = MI->getOperand(i); 287 if (!MO.isReg()) continue; 288 unsigned Reg = MO.getReg(); 289 if (Reg == 0) continue; 290 if (!MO.isUse()) continue; 291 292 const TargetRegisterClass *NewRC = 0; 293 if (i < MI->getDesc().getNumOperands()) 294 NewRC = MI->getDesc().OpInfo[i].getRegClass(TRI); 295 296 // For now, only allow the register to be changed if its register 297 // class is consistent across all uses. 298 if (!Classes[Reg] && NewRC) 299 Classes[Reg] = NewRC; 300 else if (!NewRC || Classes[Reg] != NewRC) 301 Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1); 302 303 RegRefs.insert(std::make_pair(Reg, &MO)); 304 305 // It wasn't previously live but now it is, this is a kill. 306 if (KillIndices[Reg] == ~0u) { 307 KillIndices[Reg] = Count; 308 DefIndices[Reg] = ~0u; 309 assert(((KillIndices[Reg] == ~0u) != 310 (DefIndices[Reg] == ~0u)) && 311 "Kill and Def maps aren't consistent for Reg!"); 312 } 313 // Repeat, for all aliases. 314 for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) { 315 unsigned AliasReg = *Alias; 316 if (KillIndices[AliasReg] == ~0u) { 317 KillIndices[AliasReg] = Count; 318 DefIndices[AliasReg] = ~0u; 319 } 320 } 321 } 322} 323 324unsigned 325CriticalAntiDepBreaker::findSuitableFreeRegister(MachineInstr *MI, 326 unsigned AntiDepReg, 327 unsigned LastNewReg, 328 const TargetRegisterClass *RC) 329{ 330 for (TargetRegisterClass::iterator R = RC->allocation_order_begin(MF), 331 RE = RC->allocation_order_end(MF); R != RE; ++R) { 332 unsigned NewReg = *R; 333 // Don't consider non-allocatable registers 334 if (!AllocatableSet.test(NewReg)) continue; 335 // Don't replace a register with itself. 336 if (NewReg == AntiDepReg) continue; 337 // Don't replace a register with one that was recently used to repair 338 // an anti-dependence with this AntiDepReg, because that would 339 // re-introduce that anti-dependence. 340 if (NewReg == LastNewReg) continue; 341 // If the instruction already has a def of the NewReg, it's not suitable. 342 // For example, Instruction with multiple definitions can result in this 343 // condition. 344 if (MI->modifiesRegister(NewReg, TRI)) continue; 345 // If NewReg is dead and NewReg's most recent def is not before 346 // AntiDepReg's kill, it's safe to replace AntiDepReg with NewReg. 347 assert(((KillIndices[AntiDepReg] == ~0u) != (DefIndices[AntiDepReg] == ~0u)) 348 && "Kill and Def maps aren't consistent for AntiDepReg!"); 349 assert(((KillIndices[NewReg] == ~0u) != (DefIndices[NewReg] == ~0u)) 350 && "Kill and Def maps aren't consistent for NewReg!"); 351 if (KillIndices[NewReg] != ~0u || 352 Classes[NewReg] == reinterpret_cast<TargetRegisterClass *>(-1) || 353 KillIndices[AntiDepReg] > DefIndices[NewReg]) 354 continue; 355 return NewReg; 356 } 357 358 // No registers are free and available! 359 return 0; 360} 361 362unsigned CriticalAntiDepBreaker:: 363BreakAntiDependencies(const std::vector<SUnit>& SUnits, 364 MachineBasicBlock::iterator Begin, 365 MachineBasicBlock::iterator End, 366 unsigned InsertPosIndex) { 367 // The code below assumes that there is at least one instruction, 368 // so just duck out immediately if the block is empty. 369 if (SUnits.empty()) return 0; 370 371 // Keep a map of the MachineInstr*'s back to the SUnit representing them. 372 // This is used for updating debug information. 373 DenseMap<MachineInstr*,const SUnit*> MISUnitMap; 374 375 // Find the node at the bottom of the critical path. 376 const SUnit *Max = 0; 377 for (unsigned i = 0, e = SUnits.size(); i != e; ++i) { 378 const SUnit *SU = &SUnits[i]; 379 MISUnitMap[SU->getInstr()] = SU; 380 if (!Max || SU->getDepth() + SU->Latency > Max->getDepth() + Max->Latency) 381 Max = SU; 382 } 383 384#ifndef NDEBUG 385 { 386 DEBUG(dbgs() << "Critical path has total latency " 387 << (Max->getDepth() + Max->Latency) << "\n"); 388 DEBUG(dbgs() << "Available regs:"); 389 for (unsigned Reg = 0; Reg < TRI->getNumRegs(); ++Reg) { 390 if (KillIndices[Reg] == ~0u) 391 DEBUG(dbgs() << " " << TRI->getName(Reg)); 392 } 393 DEBUG(dbgs() << '\n'); 394 } 395#endif 396 397 // Track progress along the critical path through the SUnit graph as we walk 398 // the instructions. 399 const SUnit *CriticalPathSU = Max; 400 MachineInstr *CriticalPathMI = CriticalPathSU->getInstr(); 401 402 // Consider this pattern: 403 // A = ... 404 // ... = A 405 // A = ... 406 // ... = A 407 // A = ... 408 // ... = A 409 // A = ... 410 // ... = A 411 // There are three anti-dependencies here, and without special care, 412 // we'd break all of them using the same register: 413 // A = ... 414 // ... = A 415 // B = ... 416 // ... = B 417 // B = ... 418 // ... = B 419 // B = ... 420 // ... = B 421 // because at each anti-dependence, B is the first register that 422 // isn't A which is free. This re-introduces anti-dependencies 423 // at all but one of the original anti-dependencies that we were 424 // trying to break. To avoid this, keep track of the most recent 425 // register that each register was replaced with, avoid 426 // using it to repair an anti-dependence on the same register. 427 // This lets us produce this: 428 // A = ... 429 // ... = A 430 // B = ... 431 // ... = B 432 // C = ... 433 // ... = C 434 // B = ... 435 // ... = B 436 // This still has an anti-dependence on B, but at least it isn't on the 437 // original critical path. 438 // 439 // TODO: If we tracked more than one register here, we could potentially 440 // fix that remaining critical edge too. This is a little more involved, 441 // because unlike the most recent register, less recent registers should 442 // still be considered, though only if no other registers are available. 443 std::vector<unsigned> LastNewReg(TRI->getNumRegs(), 0); 444 445 // Attempt to break anti-dependence edges on the critical path. Walk the 446 // instructions from the bottom up, tracking information about liveness 447 // as we go to help determine which registers are available. 448 unsigned Broken = 0; 449 unsigned Count = InsertPosIndex - 1; 450 for (MachineBasicBlock::iterator I = End, E = Begin; 451 I != E; --Count) { 452 MachineInstr *MI = --I; 453 if (MI->isDebugValue()) 454 continue; 455 456 // Check if this instruction has a dependence on the critical path that 457 // is an anti-dependence that we may be able to break. If it is, set 458 // AntiDepReg to the non-zero register associated with the anti-dependence. 459 // 460 // We limit our attention to the critical path as a heuristic to avoid 461 // breaking anti-dependence edges that aren't going to significantly 462 // impact the overall schedule. There are a limited number of registers 463 // and we want to save them for the important edges. 464 // 465 // TODO: Instructions with multiple defs could have multiple 466 // anti-dependencies. The current code here only knows how to break one 467 // edge per instruction. Note that we'd have to be able to break all of 468 // the anti-dependencies in an instruction in order to be effective. 469 unsigned AntiDepReg = 0; 470 if (MI == CriticalPathMI) { 471 if (const SDep *Edge = CriticalPathStep(CriticalPathSU)) { 472 const SUnit *NextSU = Edge->getSUnit(); 473 474 // Only consider anti-dependence edges. 475 if (Edge->getKind() == SDep::Anti) { 476 AntiDepReg = Edge->getReg(); 477 assert(AntiDepReg != 0 && "Anti-dependence on reg0?"); 478 if (!AllocatableSet.test(AntiDepReg)) 479 // Don't break anti-dependencies on non-allocatable registers. 480 AntiDepReg = 0; 481 else if (KeepRegs.count(AntiDepReg)) 482 // Don't break anti-dependencies if an use down below requires 483 // this exact register. 484 AntiDepReg = 0; 485 else { 486 // If the SUnit has other dependencies on the SUnit that it 487 // anti-depends on, don't bother breaking the anti-dependency 488 // since those edges would prevent such units from being 489 // scheduled past each other regardless. 490 // 491 // Also, if there are dependencies on other SUnits with the 492 // same register as the anti-dependency, don't attempt to 493 // break it. 494 for (SUnit::const_pred_iterator P = CriticalPathSU->Preds.begin(), 495 PE = CriticalPathSU->Preds.end(); P != PE; ++P) 496 if (P->getSUnit() == NextSU ? 497 (P->getKind() != SDep::Anti || P->getReg() != AntiDepReg) : 498 (P->getKind() == SDep::Data && P->getReg() == AntiDepReg)) { 499 AntiDepReg = 0; 500 break; 501 } 502 } 503 } 504 CriticalPathSU = NextSU; 505 CriticalPathMI = CriticalPathSU->getInstr(); 506 } else { 507 // We've reached the end of the critical path. 508 CriticalPathSU = 0; 509 CriticalPathMI = 0; 510 } 511 } 512 513 PrescanInstruction(MI); 514 515 // If MI's defs have a special allocation requirement, don't allow 516 // any def registers to be changed. Also assume all registers 517 // defined in a call must not be changed (ABI). 518 if (MI->getDesc().isCall() || MI->getDesc().hasExtraDefRegAllocReq() || 519 TII->isPredicated(MI)) 520 // If this instruction's defs have special allocation requirement, don't 521 // break this anti-dependency. 522 AntiDepReg = 0; 523 else if (AntiDepReg) { 524 // If this instruction has a use of AntiDepReg, breaking it 525 // is invalid. 526 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { 527 MachineOperand &MO = MI->getOperand(i); 528 if (!MO.isReg()) continue; 529 unsigned Reg = MO.getReg(); 530 if (Reg == 0) continue; 531 if (MO.isUse() && TRI->regsOverlap(AntiDepReg, Reg)) { 532 AntiDepReg = 0; 533 break; 534 } 535 } 536 } 537 538 // Determine AntiDepReg's register class, if it is live and is 539 // consistently used within a single class. 540 const TargetRegisterClass *RC = AntiDepReg != 0 ? Classes[AntiDepReg] : 0; 541 assert((AntiDepReg == 0 || RC != NULL) && 542 "Register should be live if it's causing an anti-dependence!"); 543 if (RC == reinterpret_cast<TargetRegisterClass *>(-1)) 544 AntiDepReg = 0; 545 546 // Look for a suitable register to use to break the anti-depenence. 547 // 548 // TODO: Instead of picking the first free register, consider which might 549 // be the best. 550 if (AntiDepReg != 0) { 551 if (unsigned NewReg = findSuitableFreeRegister(MI, AntiDepReg, 552 LastNewReg[AntiDepReg], 553 RC)) { 554 DEBUG(dbgs() << "Breaking anti-dependence edge on " 555 << TRI->getName(AntiDepReg) 556 << " with " << RegRefs.count(AntiDepReg) << " references" 557 << " using " << TRI->getName(NewReg) << "!\n"); 558 559 // Update the references to the old register to refer to the new 560 // register. 561 std::pair<std::multimap<unsigned, MachineOperand *>::iterator, 562 std::multimap<unsigned, MachineOperand *>::iterator> 563 Range = RegRefs.equal_range(AntiDepReg); 564 for (std::multimap<unsigned, MachineOperand *>::iterator 565 Q = Range.first, QE = Range.second; Q != QE; ++Q) { 566 Q->second->setReg(NewReg); 567 // If the SU for the instruction being updated has debug information 568 // related to the anti-dependency register, make sure to update that 569 // as well. 570 const SUnit *SU = MISUnitMap[Q->second->getParent()]; 571 if (!SU) continue; 572 for (unsigned i = 0, e = SU->DbgInstrList.size() ; i < e ; ++i) { 573 MachineInstr *DI = SU->DbgInstrList[i]; 574 assert (DI->getNumOperands()==3 && DI->getOperand(0).isReg() && 575 DI->getOperand(0).getReg() 576 && "Non register dbg_value attached to SUnit!"); 577 if (DI->getOperand(0).getReg() == AntiDepReg) 578 DI->getOperand(0).setReg(NewReg); 579 } 580 } 581 582 // We just went back in time and modified history; the 583 // liveness information for the anti-depenence reg is now 584 // inconsistent. Set the state as if it were dead. 585 Classes[NewReg] = Classes[AntiDepReg]; 586 DefIndices[NewReg] = DefIndices[AntiDepReg]; 587 KillIndices[NewReg] = KillIndices[AntiDepReg]; 588 assert(((KillIndices[NewReg] == ~0u) != 589 (DefIndices[NewReg] == ~0u)) && 590 "Kill and Def maps aren't consistent for NewReg!"); 591 592 Classes[AntiDepReg] = 0; 593 DefIndices[AntiDepReg] = KillIndices[AntiDepReg]; 594 KillIndices[AntiDepReg] = ~0u; 595 assert(((KillIndices[AntiDepReg] == ~0u) != 596 (DefIndices[AntiDepReg] == ~0u)) && 597 "Kill and Def maps aren't consistent for AntiDepReg!"); 598 599 RegRefs.erase(AntiDepReg); 600 LastNewReg[AntiDepReg] = NewReg; 601 ++Broken; 602 } 603 } 604 605 ScanInstruction(MI, Count); 606 } 607 608 return Broken; 609} 610