Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame^] | 1 | // Copyright 2014 the V8 project authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #include "src/compiler/register-allocator.h" |
| 6 | |
| 7 | #include "src/compiler/linkage.h" |
| 8 | #include "src/hydrogen.h" |
| 9 | #include "src/string-stream.h" |
| 10 | |
| 11 | namespace v8 { |
| 12 | namespace internal { |
| 13 | namespace compiler { |
| 14 | |
| 15 | static inline LifetimePosition Min(LifetimePosition a, LifetimePosition b) { |
| 16 | return a.Value() < b.Value() ? a : b; |
| 17 | } |
| 18 | |
| 19 | |
| 20 | static inline LifetimePosition Max(LifetimePosition a, LifetimePosition b) { |
| 21 | return a.Value() > b.Value() ? a : b; |
| 22 | } |
| 23 | |
| 24 | |
| 25 | UsePosition::UsePosition(LifetimePosition pos, InstructionOperand* operand, |
| 26 | InstructionOperand* hint) |
| 27 | : operand_(operand), |
| 28 | hint_(hint), |
| 29 | pos_(pos), |
| 30 | next_(NULL), |
| 31 | requires_reg_(false), |
| 32 | register_beneficial_(true) { |
| 33 | if (operand_ != NULL && operand_->IsUnallocated()) { |
| 34 | const UnallocatedOperand* unalloc = UnallocatedOperand::cast(operand_); |
| 35 | requires_reg_ = unalloc->HasRegisterPolicy(); |
| 36 | register_beneficial_ = !unalloc->HasAnyPolicy(); |
| 37 | } |
| 38 | DCHECK(pos_.IsValid()); |
| 39 | } |
| 40 | |
| 41 | |
| 42 | bool UsePosition::HasHint() const { |
| 43 | return hint_ != NULL && !hint_->IsUnallocated(); |
| 44 | } |
| 45 | |
| 46 | |
| 47 | bool UsePosition::RequiresRegister() const { return requires_reg_; } |
| 48 | |
| 49 | |
| 50 | bool UsePosition::RegisterIsBeneficial() const { return register_beneficial_; } |
| 51 | |
| 52 | |
| 53 | void UseInterval::SplitAt(LifetimePosition pos, Zone* zone) { |
| 54 | DCHECK(Contains(pos) && pos.Value() != start().Value()); |
| 55 | UseInterval* after = new (zone) UseInterval(pos, end_); |
| 56 | after->next_ = next_; |
| 57 | next_ = after; |
| 58 | end_ = pos; |
| 59 | } |
| 60 | |
| 61 | |
| 62 | #ifdef DEBUG |
| 63 | |
| 64 | |
| 65 | void LiveRange::Verify() const { |
| 66 | UsePosition* cur = first_pos_; |
| 67 | while (cur != NULL) { |
| 68 | DCHECK(Start().Value() <= cur->pos().Value() && |
| 69 | cur->pos().Value() <= End().Value()); |
| 70 | cur = cur->next(); |
| 71 | } |
| 72 | } |
| 73 | |
| 74 | |
| 75 | bool LiveRange::HasOverlap(UseInterval* target) const { |
| 76 | UseInterval* current_interval = first_interval_; |
| 77 | while (current_interval != NULL) { |
| 78 | // Intervals overlap if the start of one is contained in the other. |
| 79 | if (current_interval->Contains(target->start()) || |
| 80 | target->Contains(current_interval->start())) { |
| 81 | return true; |
| 82 | } |
| 83 | current_interval = current_interval->next(); |
| 84 | } |
| 85 | return false; |
| 86 | } |
| 87 | |
| 88 | |
| 89 | #endif |
| 90 | |
| 91 | |
| 92 | LiveRange::LiveRange(int id, Zone* zone) |
| 93 | : id_(id), |
| 94 | spilled_(false), |
| 95 | is_phi_(false), |
| 96 | is_non_loop_phi_(false), |
| 97 | kind_(UNALLOCATED_REGISTERS), |
| 98 | assigned_register_(kInvalidAssignment), |
| 99 | last_interval_(NULL), |
| 100 | first_interval_(NULL), |
| 101 | first_pos_(NULL), |
| 102 | parent_(NULL), |
| 103 | next_(NULL), |
| 104 | current_interval_(NULL), |
| 105 | last_processed_use_(NULL), |
| 106 | current_hint_operand_(NULL), |
| 107 | spill_operand_(new (zone) InstructionOperand()), |
| 108 | spill_start_index_(kMaxInt) {} |
| 109 | |
| 110 | |
| 111 | void LiveRange::set_assigned_register(int reg, Zone* zone) { |
| 112 | DCHECK(!HasRegisterAssigned() && !IsSpilled()); |
| 113 | assigned_register_ = reg; |
| 114 | ConvertOperands(zone); |
| 115 | } |
| 116 | |
| 117 | |
| 118 | void LiveRange::MakeSpilled(Zone* zone) { |
| 119 | DCHECK(!IsSpilled()); |
| 120 | DCHECK(TopLevel()->HasAllocatedSpillOperand()); |
| 121 | spilled_ = true; |
| 122 | assigned_register_ = kInvalidAssignment; |
| 123 | ConvertOperands(zone); |
| 124 | } |
| 125 | |
| 126 | |
| 127 | bool LiveRange::HasAllocatedSpillOperand() const { |
| 128 | DCHECK(spill_operand_ != NULL); |
| 129 | return !spill_operand_->IsIgnored(); |
| 130 | } |
| 131 | |
| 132 | |
| 133 | void LiveRange::SetSpillOperand(InstructionOperand* operand) { |
| 134 | DCHECK(!operand->IsUnallocated()); |
| 135 | DCHECK(spill_operand_ != NULL); |
| 136 | DCHECK(spill_operand_->IsIgnored()); |
| 137 | spill_operand_->ConvertTo(operand->kind(), operand->index()); |
| 138 | } |
| 139 | |
| 140 | |
| 141 | UsePosition* LiveRange::NextUsePosition(LifetimePosition start) { |
| 142 | UsePosition* use_pos = last_processed_use_; |
| 143 | if (use_pos == NULL) use_pos = first_pos(); |
| 144 | while (use_pos != NULL && use_pos->pos().Value() < start.Value()) { |
| 145 | use_pos = use_pos->next(); |
| 146 | } |
| 147 | last_processed_use_ = use_pos; |
| 148 | return use_pos; |
| 149 | } |
| 150 | |
| 151 | |
| 152 | UsePosition* LiveRange::NextUsePositionRegisterIsBeneficial( |
| 153 | LifetimePosition start) { |
| 154 | UsePosition* pos = NextUsePosition(start); |
| 155 | while (pos != NULL && !pos->RegisterIsBeneficial()) { |
| 156 | pos = pos->next(); |
| 157 | } |
| 158 | return pos; |
| 159 | } |
| 160 | |
| 161 | |
| 162 | UsePosition* LiveRange::PreviousUsePositionRegisterIsBeneficial( |
| 163 | LifetimePosition start) { |
| 164 | UsePosition* pos = first_pos(); |
| 165 | UsePosition* prev = NULL; |
| 166 | while (pos != NULL && pos->pos().Value() < start.Value()) { |
| 167 | if (pos->RegisterIsBeneficial()) prev = pos; |
| 168 | pos = pos->next(); |
| 169 | } |
| 170 | return prev; |
| 171 | } |
| 172 | |
| 173 | |
| 174 | UsePosition* LiveRange::NextRegisterPosition(LifetimePosition start) { |
| 175 | UsePosition* pos = NextUsePosition(start); |
| 176 | while (pos != NULL && !pos->RequiresRegister()) { |
| 177 | pos = pos->next(); |
| 178 | } |
| 179 | return pos; |
| 180 | } |
| 181 | |
| 182 | |
| 183 | bool LiveRange::CanBeSpilled(LifetimePosition pos) { |
| 184 | // We cannot spill a live range that has a use requiring a register |
| 185 | // at the current or the immediate next position. |
| 186 | UsePosition* use_pos = NextRegisterPosition(pos); |
| 187 | if (use_pos == NULL) return true; |
| 188 | return use_pos->pos().Value() > |
| 189 | pos.NextInstruction().InstructionEnd().Value(); |
| 190 | } |
| 191 | |
| 192 | |
| 193 | InstructionOperand* LiveRange::CreateAssignedOperand(Zone* zone) { |
| 194 | InstructionOperand* op = NULL; |
| 195 | if (HasRegisterAssigned()) { |
| 196 | DCHECK(!IsSpilled()); |
| 197 | switch (Kind()) { |
| 198 | case GENERAL_REGISTERS: |
| 199 | op = RegisterOperand::Create(assigned_register(), zone); |
| 200 | break; |
| 201 | case DOUBLE_REGISTERS: |
| 202 | op = DoubleRegisterOperand::Create(assigned_register(), zone); |
| 203 | break; |
| 204 | default: |
| 205 | UNREACHABLE(); |
| 206 | } |
| 207 | } else if (IsSpilled()) { |
| 208 | DCHECK(!HasRegisterAssigned()); |
| 209 | op = TopLevel()->GetSpillOperand(); |
| 210 | DCHECK(!op->IsUnallocated()); |
| 211 | } else { |
| 212 | UnallocatedOperand* unalloc = |
| 213 | new (zone) UnallocatedOperand(UnallocatedOperand::NONE); |
| 214 | unalloc->set_virtual_register(id_); |
| 215 | op = unalloc; |
| 216 | } |
| 217 | return op; |
| 218 | } |
| 219 | |
| 220 | |
| 221 | UseInterval* LiveRange::FirstSearchIntervalForPosition( |
| 222 | LifetimePosition position) const { |
| 223 | if (current_interval_ == NULL) return first_interval_; |
| 224 | if (current_interval_->start().Value() > position.Value()) { |
| 225 | current_interval_ = NULL; |
| 226 | return first_interval_; |
| 227 | } |
| 228 | return current_interval_; |
| 229 | } |
| 230 | |
| 231 | |
| 232 | void LiveRange::AdvanceLastProcessedMarker( |
| 233 | UseInterval* to_start_of, LifetimePosition but_not_past) const { |
| 234 | if (to_start_of == NULL) return; |
| 235 | if (to_start_of->start().Value() > but_not_past.Value()) return; |
| 236 | LifetimePosition start = current_interval_ == NULL |
| 237 | ? LifetimePosition::Invalid() |
| 238 | : current_interval_->start(); |
| 239 | if (to_start_of->start().Value() > start.Value()) { |
| 240 | current_interval_ = to_start_of; |
| 241 | } |
| 242 | } |
| 243 | |
| 244 | |
| 245 | void LiveRange::SplitAt(LifetimePosition position, LiveRange* result, |
| 246 | Zone* zone) { |
| 247 | DCHECK(Start().Value() < position.Value()); |
| 248 | DCHECK(result->IsEmpty()); |
| 249 | // Find the last interval that ends before the position. If the |
| 250 | // position is contained in one of the intervals in the chain, we |
| 251 | // split that interval and use the first part. |
| 252 | UseInterval* current = FirstSearchIntervalForPosition(position); |
| 253 | |
| 254 | // If the split position coincides with the beginning of a use interval |
| 255 | // we need to split use positons in a special way. |
| 256 | bool split_at_start = false; |
| 257 | |
| 258 | if (current->start().Value() == position.Value()) { |
| 259 | // When splitting at start we need to locate the previous use interval. |
| 260 | current = first_interval_; |
| 261 | } |
| 262 | |
| 263 | while (current != NULL) { |
| 264 | if (current->Contains(position)) { |
| 265 | current->SplitAt(position, zone); |
| 266 | break; |
| 267 | } |
| 268 | UseInterval* next = current->next(); |
| 269 | if (next->start().Value() >= position.Value()) { |
| 270 | split_at_start = (next->start().Value() == position.Value()); |
| 271 | break; |
| 272 | } |
| 273 | current = next; |
| 274 | } |
| 275 | |
| 276 | // Partition original use intervals to the two live ranges. |
| 277 | UseInterval* before = current; |
| 278 | UseInterval* after = before->next(); |
| 279 | result->last_interval_ = |
| 280 | (last_interval_ == before) |
| 281 | ? after // Only interval in the range after split. |
| 282 | : last_interval_; // Last interval of the original range. |
| 283 | result->first_interval_ = after; |
| 284 | last_interval_ = before; |
| 285 | |
| 286 | // Find the last use position before the split and the first use |
| 287 | // position after it. |
| 288 | UsePosition* use_after = first_pos_; |
| 289 | UsePosition* use_before = NULL; |
| 290 | if (split_at_start) { |
| 291 | // The split position coincides with the beginning of a use interval (the |
| 292 | // end of a lifetime hole). Use at this position should be attributed to |
| 293 | // the split child because split child owns use interval covering it. |
| 294 | while (use_after != NULL && use_after->pos().Value() < position.Value()) { |
| 295 | use_before = use_after; |
| 296 | use_after = use_after->next(); |
| 297 | } |
| 298 | } else { |
| 299 | while (use_after != NULL && use_after->pos().Value() <= position.Value()) { |
| 300 | use_before = use_after; |
| 301 | use_after = use_after->next(); |
| 302 | } |
| 303 | } |
| 304 | |
| 305 | // Partition original use positions to the two live ranges. |
| 306 | if (use_before != NULL) { |
| 307 | use_before->next_ = NULL; |
| 308 | } else { |
| 309 | first_pos_ = NULL; |
| 310 | } |
| 311 | result->first_pos_ = use_after; |
| 312 | |
| 313 | // Discard cached iteration state. It might be pointing |
| 314 | // to the use that no longer belongs to this live range. |
| 315 | last_processed_use_ = NULL; |
| 316 | current_interval_ = NULL; |
| 317 | |
| 318 | // Link the new live range in the chain before any of the other |
| 319 | // ranges linked from the range before the split. |
| 320 | result->parent_ = (parent_ == NULL) ? this : parent_; |
| 321 | result->kind_ = result->parent_->kind_; |
| 322 | result->next_ = next_; |
| 323 | next_ = result; |
| 324 | |
| 325 | #ifdef DEBUG |
| 326 | Verify(); |
| 327 | result->Verify(); |
| 328 | #endif |
| 329 | } |
| 330 | |
| 331 | |
| 332 | // This implements an ordering on live ranges so that they are ordered by their |
| 333 | // start positions. This is needed for the correctness of the register |
| 334 | // allocation algorithm. If two live ranges start at the same offset then there |
| 335 | // is a tie breaker based on where the value is first used. This part of the |
| 336 | // ordering is merely a heuristic. |
| 337 | bool LiveRange::ShouldBeAllocatedBefore(const LiveRange* other) const { |
| 338 | LifetimePosition start = Start(); |
| 339 | LifetimePosition other_start = other->Start(); |
| 340 | if (start.Value() == other_start.Value()) { |
| 341 | UsePosition* pos = first_pos(); |
| 342 | if (pos == NULL) return false; |
| 343 | UsePosition* other_pos = other->first_pos(); |
| 344 | if (other_pos == NULL) return true; |
| 345 | return pos->pos().Value() < other_pos->pos().Value(); |
| 346 | } |
| 347 | return start.Value() < other_start.Value(); |
| 348 | } |
| 349 | |
| 350 | |
| 351 | void LiveRange::ShortenTo(LifetimePosition start) { |
| 352 | RegisterAllocator::TraceAlloc("Shorten live range %d to [%d\n", id_, |
| 353 | start.Value()); |
| 354 | DCHECK(first_interval_ != NULL); |
| 355 | DCHECK(first_interval_->start().Value() <= start.Value()); |
| 356 | DCHECK(start.Value() < first_interval_->end().Value()); |
| 357 | first_interval_->set_start(start); |
| 358 | } |
| 359 | |
| 360 | |
| 361 | void LiveRange::EnsureInterval(LifetimePosition start, LifetimePosition end, |
| 362 | Zone* zone) { |
| 363 | RegisterAllocator::TraceAlloc("Ensure live range %d in interval [%d %d[\n", |
| 364 | id_, start.Value(), end.Value()); |
| 365 | LifetimePosition new_end = end; |
| 366 | while (first_interval_ != NULL && |
| 367 | first_interval_->start().Value() <= end.Value()) { |
| 368 | if (first_interval_->end().Value() > end.Value()) { |
| 369 | new_end = first_interval_->end(); |
| 370 | } |
| 371 | first_interval_ = first_interval_->next(); |
| 372 | } |
| 373 | |
| 374 | UseInterval* new_interval = new (zone) UseInterval(start, new_end); |
| 375 | new_interval->next_ = first_interval_; |
| 376 | first_interval_ = new_interval; |
| 377 | if (new_interval->next() == NULL) { |
| 378 | last_interval_ = new_interval; |
| 379 | } |
| 380 | } |
| 381 | |
| 382 | |
| 383 | void LiveRange::AddUseInterval(LifetimePosition start, LifetimePosition end, |
| 384 | Zone* zone) { |
| 385 | RegisterAllocator::TraceAlloc("Add to live range %d interval [%d %d[\n", id_, |
| 386 | start.Value(), end.Value()); |
| 387 | if (first_interval_ == NULL) { |
| 388 | UseInterval* interval = new (zone) UseInterval(start, end); |
| 389 | first_interval_ = interval; |
| 390 | last_interval_ = interval; |
| 391 | } else { |
| 392 | if (end.Value() == first_interval_->start().Value()) { |
| 393 | first_interval_->set_start(start); |
| 394 | } else if (end.Value() < first_interval_->start().Value()) { |
| 395 | UseInterval* interval = new (zone) UseInterval(start, end); |
| 396 | interval->set_next(first_interval_); |
| 397 | first_interval_ = interval; |
| 398 | } else { |
| 399 | // Order of instruction's processing (see ProcessInstructions) guarantees |
| 400 | // that each new use interval either precedes or intersects with |
| 401 | // last added interval. |
| 402 | DCHECK(start.Value() < first_interval_->end().Value()); |
| 403 | first_interval_->start_ = Min(start, first_interval_->start_); |
| 404 | first_interval_->end_ = Max(end, first_interval_->end_); |
| 405 | } |
| 406 | } |
| 407 | } |
| 408 | |
| 409 | |
| 410 | void LiveRange::AddUsePosition(LifetimePosition pos, |
| 411 | InstructionOperand* operand, |
| 412 | InstructionOperand* hint, Zone* zone) { |
| 413 | RegisterAllocator::TraceAlloc("Add to live range %d use position %d\n", id_, |
| 414 | pos.Value()); |
| 415 | UsePosition* use_pos = new (zone) UsePosition(pos, operand, hint); |
| 416 | UsePosition* prev_hint = NULL; |
| 417 | UsePosition* prev = NULL; |
| 418 | UsePosition* current = first_pos_; |
| 419 | while (current != NULL && current->pos().Value() < pos.Value()) { |
| 420 | prev_hint = current->HasHint() ? current : prev_hint; |
| 421 | prev = current; |
| 422 | current = current->next(); |
| 423 | } |
| 424 | |
| 425 | if (prev == NULL) { |
| 426 | use_pos->set_next(first_pos_); |
| 427 | first_pos_ = use_pos; |
| 428 | } else { |
| 429 | use_pos->next_ = prev->next_; |
| 430 | prev->next_ = use_pos; |
| 431 | } |
| 432 | |
| 433 | if (prev_hint == NULL && use_pos->HasHint()) { |
| 434 | current_hint_operand_ = hint; |
| 435 | } |
| 436 | } |
| 437 | |
| 438 | |
| 439 | void LiveRange::ConvertOperands(Zone* zone) { |
| 440 | InstructionOperand* op = CreateAssignedOperand(zone); |
| 441 | UsePosition* use_pos = first_pos(); |
| 442 | while (use_pos != NULL) { |
| 443 | DCHECK(Start().Value() <= use_pos->pos().Value() && |
| 444 | use_pos->pos().Value() <= End().Value()); |
| 445 | |
| 446 | if (use_pos->HasOperand()) { |
| 447 | DCHECK(op->IsRegister() || op->IsDoubleRegister() || |
| 448 | !use_pos->RequiresRegister()); |
| 449 | use_pos->operand()->ConvertTo(op->kind(), op->index()); |
| 450 | } |
| 451 | use_pos = use_pos->next(); |
| 452 | } |
| 453 | } |
| 454 | |
| 455 | |
| 456 | bool LiveRange::CanCover(LifetimePosition position) const { |
| 457 | if (IsEmpty()) return false; |
| 458 | return Start().Value() <= position.Value() && |
| 459 | position.Value() < End().Value(); |
| 460 | } |
| 461 | |
| 462 | |
| 463 | bool LiveRange::Covers(LifetimePosition position) { |
| 464 | if (!CanCover(position)) return false; |
| 465 | UseInterval* start_search = FirstSearchIntervalForPosition(position); |
| 466 | for (UseInterval* interval = start_search; interval != NULL; |
| 467 | interval = interval->next()) { |
| 468 | DCHECK(interval->next() == NULL || |
| 469 | interval->next()->start().Value() >= interval->start().Value()); |
| 470 | AdvanceLastProcessedMarker(interval, position); |
| 471 | if (interval->Contains(position)) return true; |
| 472 | if (interval->start().Value() > position.Value()) return false; |
| 473 | } |
| 474 | return false; |
| 475 | } |
| 476 | |
| 477 | |
| 478 | LifetimePosition LiveRange::FirstIntersection(LiveRange* other) { |
| 479 | UseInterval* b = other->first_interval(); |
| 480 | if (b == NULL) return LifetimePosition::Invalid(); |
| 481 | LifetimePosition advance_last_processed_up_to = b->start(); |
| 482 | UseInterval* a = FirstSearchIntervalForPosition(b->start()); |
| 483 | while (a != NULL && b != NULL) { |
| 484 | if (a->start().Value() > other->End().Value()) break; |
| 485 | if (b->start().Value() > End().Value()) break; |
| 486 | LifetimePosition cur_intersection = a->Intersect(b); |
| 487 | if (cur_intersection.IsValid()) { |
| 488 | return cur_intersection; |
| 489 | } |
| 490 | if (a->start().Value() < b->start().Value()) { |
| 491 | a = a->next(); |
| 492 | if (a == NULL || a->start().Value() > other->End().Value()) break; |
| 493 | AdvanceLastProcessedMarker(a, advance_last_processed_up_to); |
| 494 | } else { |
| 495 | b = b->next(); |
| 496 | } |
| 497 | } |
| 498 | return LifetimePosition::Invalid(); |
| 499 | } |
| 500 | |
| 501 | |
| 502 | RegisterAllocator::RegisterAllocator(InstructionSequence* code) |
| 503 | : zone_(code->isolate()), |
| 504 | code_(code), |
| 505 | live_in_sets_(code->BasicBlockCount(), zone()), |
| 506 | live_ranges_(code->VirtualRegisterCount() * 2, zone()), |
| 507 | fixed_live_ranges_(NULL), |
| 508 | fixed_double_live_ranges_(NULL), |
| 509 | unhandled_live_ranges_(code->VirtualRegisterCount() * 2, zone()), |
| 510 | active_live_ranges_(8, zone()), |
| 511 | inactive_live_ranges_(8, zone()), |
| 512 | reusable_slots_(8, zone()), |
| 513 | mode_(UNALLOCATED_REGISTERS), |
| 514 | num_registers_(-1), |
| 515 | allocation_ok_(true) {} |
| 516 | |
| 517 | |
| 518 | void RegisterAllocator::InitializeLivenessAnalysis() { |
| 519 | // Initialize the live_in sets for each block to NULL. |
| 520 | int block_count = code()->BasicBlockCount(); |
| 521 | live_in_sets_.Initialize(block_count, zone()); |
| 522 | live_in_sets_.AddBlock(NULL, block_count, zone()); |
| 523 | } |
| 524 | |
| 525 | |
| 526 | BitVector* RegisterAllocator::ComputeLiveOut(BasicBlock* block) { |
| 527 | // Compute live out for the given block, except not including backward |
| 528 | // successor edges. |
| 529 | BitVector* live_out = |
| 530 | new (zone()) BitVector(code()->VirtualRegisterCount(), zone()); |
| 531 | |
| 532 | // Process all successor blocks. |
| 533 | BasicBlock::Successors successors = block->successors(); |
| 534 | for (BasicBlock::Successors::iterator i = successors.begin(); |
| 535 | i != successors.end(); ++i) { |
| 536 | // Add values live on entry to the successor. Note the successor's |
| 537 | // live_in will not be computed yet for backwards edges. |
| 538 | BasicBlock* successor = *i; |
| 539 | BitVector* live_in = live_in_sets_[successor->rpo_number_]; |
| 540 | if (live_in != NULL) live_out->Union(*live_in); |
| 541 | |
| 542 | // All phi input operands corresponding to this successor edge are live |
| 543 | // out from this block. |
| 544 | int index = successor->PredecessorIndexOf(block); |
| 545 | DCHECK(index >= 0); |
| 546 | DCHECK(index < static_cast<int>(successor->PredecessorCount())); |
| 547 | for (BasicBlock::const_iterator j = successor->begin(); |
| 548 | j != successor->end(); ++j) { |
| 549 | Node* phi = *j; |
| 550 | if (phi->opcode() != IrOpcode::kPhi) continue; |
| 551 | Node* input = phi->InputAt(index); |
| 552 | live_out->Add(input->id()); |
| 553 | } |
| 554 | } |
| 555 | |
| 556 | return live_out; |
| 557 | } |
| 558 | |
| 559 | |
| 560 | void RegisterAllocator::AddInitialIntervals(BasicBlock* block, |
| 561 | BitVector* live_out) { |
| 562 | // Add an interval that includes the entire block to the live range for |
| 563 | // each live_out value. |
| 564 | LifetimePosition start = |
| 565 | LifetimePosition::FromInstructionIndex(block->first_instruction_index()); |
| 566 | LifetimePosition end = LifetimePosition::FromInstructionIndex( |
| 567 | block->last_instruction_index()).NextInstruction(); |
| 568 | BitVector::Iterator iterator(live_out); |
| 569 | while (!iterator.Done()) { |
| 570 | int operand_index = iterator.Current(); |
| 571 | LiveRange* range = LiveRangeFor(operand_index); |
| 572 | range->AddUseInterval(start, end, zone()); |
| 573 | iterator.Advance(); |
| 574 | } |
| 575 | } |
| 576 | |
| 577 | |
| 578 | int RegisterAllocator::FixedDoubleLiveRangeID(int index) { |
| 579 | return -index - 1 - Register::kMaxNumAllocatableRegisters; |
| 580 | } |
| 581 | |
| 582 | |
| 583 | InstructionOperand* RegisterAllocator::AllocateFixed( |
| 584 | UnallocatedOperand* operand, int pos, bool is_tagged) { |
| 585 | TraceAlloc("Allocating fixed reg for op %d\n", operand->virtual_register()); |
| 586 | DCHECK(operand->HasFixedPolicy()); |
| 587 | if (operand->HasFixedSlotPolicy()) { |
| 588 | operand->ConvertTo(InstructionOperand::STACK_SLOT, |
| 589 | operand->fixed_slot_index()); |
| 590 | } else if (operand->HasFixedRegisterPolicy()) { |
| 591 | int reg_index = operand->fixed_register_index(); |
| 592 | operand->ConvertTo(InstructionOperand::REGISTER, reg_index); |
| 593 | } else if (operand->HasFixedDoubleRegisterPolicy()) { |
| 594 | int reg_index = operand->fixed_register_index(); |
| 595 | operand->ConvertTo(InstructionOperand::DOUBLE_REGISTER, reg_index); |
| 596 | } else { |
| 597 | UNREACHABLE(); |
| 598 | } |
| 599 | if (is_tagged) { |
| 600 | TraceAlloc("Fixed reg is tagged at %d\n", pos); |
| 601 | Instruction* instr = InstructionAt(pos); |
| 602 | if (instr->HasPointerMap()) { |
| 603 | instr->pointer_map()->RecordPointer(operand, code_zone()); |
| 604 | } |
| 605 | } |
| 606 | return operand; |
| 607 | } |
| 608 | |
| 609 | |
| 610 | LiveRange* RegisterAllocator::FixedLiveRangeFor(int index) { |
| 611 | DCHECK(index < Register::kMaxNumAllocatableRegisters); |
| 612 | LiveRange* result = fixed_live_ranges_[index]; |
| 613 | if (result == NULL) { |
| 614 | // TODO(titzer): add a utility method to allocate a new LiveRange: |
| 615 | // The LiveRange object itself can go in this zone, but the |
| 616 | // InstructionOperand needs |
| 617 | // to go in the code zone, since it may survive register allocation. |
| 618 | result = new (zone()) LiveRange(FixedLiveRangeID(index), code_zone()); |
| 619 | DCHECK(result->IsFixed()); |
| 620 | result->kind_ = GENERAL_REGISTERS; |
| 621 | SetLiveRangeAssignedRegister(result, index); |
| 622 | fixed_live_ranges_[index] = result; |
| 623 | } |
| 624 | return result; |
| 625 | } |
| 626 | |
| 627 | |
| 628 | LiveRange* RegisterAllocator::FixedDoubleLiveRangeFor(int index) { |
| 629 | DCHECK(index < DoubleRegister::NumAllocatableRegisters()); |
| 630 | LiveRange* result = fixed_double_live_ranges_[index]; |
| 631 | if (result == NULL) { |
| 632 | result = new (zone()) LiveRange(FixedDoubleLiveRangeID(index), code_zone()); |
| 633 | DCHECK(result->IsFixed()); |
| 634 | result->kind_ = DOUBLE_REGISTERS; |
| 635 | SetLiveRangeAssignedRegister(result, index); |
| 636 | fixed_double_live_ranges_[index] = result; |
| 637 | } |
| 638 | return result; |
| 639 | } |
| 640 | |
| 641 | |
| 642 | LiveRange* RegisterAllocator::LiveRangeFor(int index) { |
| 643 | if (index >= live_ranges_.length()) { |
| 644 | live_ranges_.AddBlock(NULL, index - live_ranges_.length() + 1, zone()); |
| 645 | } |
| 646 | LiveRange* result = live_ranges_[index]; |
| 647 | if (result == NULL) { |
| 648 | result = new (zone()) LiveRange(index, code_zone()); |
| 649 | live_ranges_[index] = result; |
| 650 | } |
| 651 | return result; |
| 652 | } |
| 653 | |
| 654 | |
| 655 | GapInstruction* RegisterAllocator::GetLastGap(BasicBlock* block) { |
| 656 | int last_instruction = block->last_instruction_index(); |
| 657 | return code()->GapAt(last_instruction - 1); |
| 658 | } |
| 659 | |
| 660 | |
| 661 | LiveRange* RegisterAllocator::LiveRangeFor(InstructionOperand* operand) { |
| 662 | if (operand->IsUnallocated()) { |
| 663 | return LiveRangeFor(UnallocatedOperand::cast(operand)->virtual_register()); |
| 664 | } else if (operand->IsRegister()) { |
| 665 | return FixedLiveRangeFor(operand->index()); |
| 666 | } else if (operand->IsDoubleRegister()) { |
| 667 | return FixedDoubleLiveRangeFor(operand->index()); |
| 668 | } else { |
| 669 | return NULL; |
| 670 | } |
| 671 | } |
| 672 | |
| 673 | |
| 674 | void RegisterAllocator::Define(LifetimePosition position, |
| 675 | InstructionOperand* operand, |
| 676 | InstructionOperand* hint) { |
| 677 | LiveRange* range = LiveRangeFor(operand); |
| 678 | if (range == NULL) return; |
| 679 | |
| 680 | if (range->IsEmpty() || range->Start().Value() > position.Value()) { |
| 681 | // Can happen if there is a definition without use. |
| 682 | range->AddUseInterval(position, position.NextInstruction(), zone()); |
| 683 | range->AddUsePosition(position.NextInstruction(), NULL, NULL, zone()); |
| 684 | } else { |
| 685 | range->ShortenTo(position); |
| 686 | } |
| 687 | |
| 688 | if (operand->IsUnallocated()) { |
| 689 | UnallocatedOperand* unalloc_operand = UnallocatedOperand::cast(operand); |
| 690 | range->AddUsePosition(position, unalloc_operand, hint, zone()); |
| 691 | } |
| 692 | } |
| 693 | |
| 694 | |
| 695 | void RegisterAllocator::Use(LifetimePosition block_start, |
| 696 | LifetimePosition position, |
| 697 | InstructionOperand* operand, |
| 698 | InstructionOperand* hint) { |
| 699 | LiveRange* range = LiveRangeFor(operand); |
| 700 | if (range == NULL) return; |
| 701 | if (operand->IsUnallocated()) { |
| 702 | UnallocatedOperand* unalloc_operand = UnallocatedOperand::cast(operand); |
| 703 | range->AddUsePosition(position, unalloc_operand, hint, zone()); |
| 704 | } |
| 705 | range->AddUseInterval(block_start, position, zone()); |
| 706 | } |
| 707 | |
| 708 | |
| 709 | void RegisterAllocator::AddConstraintsGapMove(int index, |
| 710 | InstructionOperand* from, |
| 711 | InstructionOperand* to) { |
| 712 | GapInstruction* gap = code()->GapAt(index); |
| 713 | ParallelMove* move = |
| 714 | gap->GetOrCreateParallelMove(GapInstruction::START, code_zone()); |
| 715 | if (from->IsUnallocated()) { |
| 716 | const ZoneList<MoveOperands>* move_operands = move->move_operands(); |
| 717 | for (int i = 0; i < move_operands->length(); ++i) { |
| 718 | MoveOperands cur = move_operands->at(i); |
| 719 | InstructionOperand* cur_to = cur.destination(); |
| 720 | if (cur_to->IsUnallocated()) { |
| 721 | if (UnallocatedOperand::cast(cur_to)->virtual_register() == |
| 722 | UnallocatedOperand::cast(from)->virtual_register()) { |
| 723 | move->AddMove(cur.source(), to, code_zone()); |
| 724 | return; |
| 725 | } |
| 726 | } |
| 727 | } |
| 728 | } |
| 729 | move->AddMove(from, to, code_zone()); |
| 730 | } |
| 731 | |
| 732 | |
| 733 | void RegisterAllocator::MeetRegisterConstraints(BasicBlock* block) { |
| 734 | int start = block->first_instruction_index(); |
| 735 | int end = block->last_instruction_index(); |
| 736 | DCHECK_NE(-1, start); |
| 737 | for (int i = start; i <= end; ++i) { |
| 738 | if (code()->IsGapAt(i)) { |
| 739 | Instruction* instr = NULL; |
| 740 | Instruction* prev_instr = NULL; |
| 741 | if (i < end) instr = InstructionAt(i + 1); |
| 742 | if (i > start) prev_instr = InstructionAt(i - 1); |
| 743 | MeetConstraintsBetween(prev_instr, instr, i); |
| 744 | if (!AllocationOk()) return; |
| 745 | } |
| 746 | } |
| 747 | |
| 748 | // Meet register constraints for the instruction in the end. |
| 749 | if (!code()->IsGapAt(end)) { |
| 750 | MeetRegisterConstraintsForLastInstructionInBlock(block); |
| 751 | } |
| 752 | } |
| 753 | |
| 754 | |
| 755 | void RegisterAllocator::MeetRegisterConstraintsForLastInstructionInBlock( |
| 756 | BasicBlock* block) { |
| 757 | int end = block->last_instruction_index(); |
| 758 | Instruction* last_instruction = InstructionAt(end); |
| 759 | for (size_t i = 0; i < last_instruction->OutputCount(); i++) { |
| 760 | InstructionOperand* output_operand = last_instruction->OutputAt(i); |
| 761 | DCHECK(!output_operand->IsConstant()); |
| 762 | UnallocatedOperand* output = UnallocatedOperand::cast(output_operand); |
| 763 | int output_vreg = output->virtual_register(); |
| 764 | LiveRange* range = LiveRangeFor(output_vreg); |
| 765 | bool assigned = false; |
| 766 | if (output->HasFixedPolicy()) { |
| 767 | AllocateFixed(output, -1, false); |
| 768 | // This value is produced on the stack, we never need to spill it. |
| 769 | if (output->IsStackSlot()) { |
| 770 | range->SetSpillOperand(output); |
| 771 | range->SetSpillStartIndex(end); |
| 772 | assigned = true; |
| 773 | } |
| 774 | |
| 775 | BasicBlock::Successors successors = block->successors(); |
| 776 | for (BasicBlock::Successors::iterator succ = successors.begin(); |
| 777 | succ != successors.end(); ++succ) { |
| 778 | DCHECK((*succ)->PredecessorCount() == 1); |
| 779 | int gap_index = (*succ)->first_instruction_index() + 1; |
| 780 | DCHECK(code()->IsGapAt(gap_index)); |
| 781 | |
| 782 | // Create an unconstrained operand for the same virtual register |
| 783 | // and insert a gap move from the fixed output to the operand. |
| 784 | UnallocatedOperand* output_copy = |
| 785 | new (code_zone()) UnallocatedOperand(UnallocatedOperand::ANY); |
| 786 | output_copy->set_virtual_register(output_vreg); |
| 787 | |
| 788 | code()->AddGapMove(gap_index, output, output_copy); |
| 789 | } |
| 790 | } |
| 791 | |
| 792 | if (!assigned) { |
| 793 | BasicBlock::Successors successors = block->successors(); |
| 794 | for (BasicBlock::Successors::iterator succ = successors.begin(); |
| 795 | succ != successors.end(); ++succ) { |
| 796 | DCHECK((*succ)->PredecessorCount() == 1); |
| 797 | int gap_index = (*succ)->first_instruction_index() + 1; |
| 798 | range->SetSpillStartIndex(gap_index); |
| 799 | |
| 800 | // This move to spill operand is not a real use. Liveness analysis |
| 801 | // and splitting of live ranges do not account for it. |
| 802 | // Thus it should be inserted to a lifetime position corresponding to |
| 803 | // the instruction end. |
| 804 | GapInstruction* gap = code()->GapAt(gap_index); |
| 805 | ParallelMove* move = |
| 806 | gap->GetOrCreateParallelMove(GapInstruction::BEFORE, code_zone()); |
| 807 | move->AddMove(output, range->GetSpillOperand(), code_zone()); |
| 808 | } |
| 809 | } |
| 810 | } |
| 811 | } |
| 812 | |
| 813 | |
| 814 | void RegisterAllocator::MeetConstraintsBetween(Instruction* first, |
| 815 | Instruction* second, |
| 816 | int gap_index) { |
| 817 | if (first != NULL) { |
| 818 | // Handle fixed temporaries. |
| 819 | for (size_t i = 0; i < first->TempCount(); i++) { |
| 820 | UnallocatedOperand* temp = UnallocatedOperand::cast(first->TempAt(i)); |
| 821 | if (temp->HasFixedPolicy()) { |
| 822 | AllocateFixed(temp, gap_index - 1, false); |
| 823 | } |
| 824 | } |
| 825 | |
| 826 | // Handle constant/fixed output operands. |
| 827 | for (size_t i = 0; i < first->OutputCount(); i++) { |
| 828 | InstructionOperand* output = first->OutputAt(i); |
| 829 | if (output->IsConstant()) { |
| 830 | int output_vreg = output->index(); |
| 831 | LiveRange* range = LiveRangeFor(output_vreg); |
| 832 | range->SetSpillStartIndex(gap_index - 1); |
| 833 | range->SetSpillOperand(output); |
| 834 | } else { |
| 835 | UnallocatedOperand* first_output = UnallocatedOperand::cast(output); |
| 836 | LiveRange* range = LiveRangeFor(first_output->virtual_register()); |
| 837 | bool assigned = false; |
| 838 | if (first_output->HasFixedPolicy()) { |
| 839 | UnallocatedOperand* output_copy = |
| 840 | first_output->CopyUnconstrained(code_zone()); |
| 841 | bool is_tagged = HasTaggedValue(first_output->virtual_register()); |
| 842 | AllocateFixed(first_output, gap_index, is_tagged); |
| 843 | |
| 844 | // This value is produced on the stack, we never need to spill it. |
| 845 | if (first_output->IsStackSlot()) { |
| 846 | range->SetSpillOperand(first_output); |
| 847 | range->SetSpillStartIndex(gap_index - 1); |
| 848 | assigned = true; |
| 849 | } |
| 850 | code()->AddGapMove(gap_index, first_output, output_copy); |
| 851 | } |
| 852 | |
| 853 | // Make sure we add a gap move for spilling (if we have not done |
| 854 | // so already). |
| 855 | if (!assigned) { |
| 856 | range->SetSpillStartIndex(gap_index); |
| 857 | |
| 858 | // This move to spill operand is not a real use. Liveness analysis |
| 859 | // and splitting of live ranges do not account for it. |
| 860 | // Thus it should be inserted to a lifetime position corresponding to |
| 861 | // the instruction end. |
| 862 | GapInstruction* gap = code()->GapAt(gap_index); |
| 863 | ParallelMove* move = |
| 864 | gap->GetOrCreateParallelMove(GapInstruction::BEFORE, code_zone()); |
| 865 | move->AddMove(first_output, range->GetSpillOperand(), code_zone()); |
| 866 | } |
| 867 | } |
| 868 | } |
| 869 | } |
| 870 | |
| 871 | if (second != NULL) { |
| 872 | // Handle fixed input operands of second instruction. |
| 873 | for (size_t i = 0; i < second->InputCount(); i++) { |
| 874 | InstructionOperand* input = second->InputAt(i); |
| 875 | if (input->IsImmediate()) continue; // Ignore immediates. |
| 876 | UnallocatedOperand* cur_input = UnallocatedOperand::cast(input); |
| 877 | if (cur_input->HasFixedPolicy()) { |
| 878 | UnallocatedOperand* input_copy = |
| 879 | cur_input->CopyUnconstrained(code_zone()); |
| 880 | bool is_tagged = HasTaggedValue(cur_input->virtual_register()); |
| 881 | AllocateFixed(cur_input, gap_index + 1, is_tagged); |
| 882 | AddConstraintsGapMove(gap_index, input_copy, cur_input); |
| 883 | } |
| 884 | } |
| 885 | |
| 886 | // Handle "output same as input" for second instruction. |
| 887 | for (size_t i = 0; i < second->OutputCount(); i++) { |
| 888 | InstructionOperand* output = second->OutputAt(i); |
| 889 | if (!output->IsUnallocated()) continue; |
| 890 | UnallocatedOperand* second_output = UnallocatedOperand::cast(output); |
| 891 | if (second_output->HasSameAsInputPolicy()) { |
| 892 | DCHECK(i == 0); // Only valid for first output. |
| 893 | UnallocatedOperand* cur_input = |
| 894 | UnallocatedOperand::cast(second->InputAt(0)); |
| 895 | int output_vreg = second_output->virtual_register(); |
| 896 | int input_vreg = cur_input->virtual_register(); |
| 897 | |
| 898 | UnallocatedOperand* input_copy = |
| 899 | cur_input->CopyUnconstrained(code_zone()); |
| 900 | cur_input->set_virtual_register(second_output->virtual_register()); |
| 901 | AddConstraintsGapMove(gap_index, input_copy, cur_input); |
| 902 | |
| 903 | if (HasTaggedValue(input_vreg) && !HasTaggedValue(output_vreg)) { |
| 904 | int index = gap_index + 1; |
| 905 | Instruction* instr = InstructionAt(index); |
| 906 | if (instr->HasPointerMap()) { |
| 907 | instr->pointer_map()->RecordPointer(input_copy, code_zone()); |
| 908 | } |
| 909 | } else if (!HasTaggedValue(input_vreg) && HasTaggedValue(output_vreg)) { |
| 910 | // The input is assumed to immediately have a tagged representation, |
| 911 | // before the pointer map can be used. I.e. the pointer map at the |
| 912 | // instruction will include the output operand (whose value at the |
| 913 | // beginning of the instruction is equal to the input operand). If |
| 914 | // this is not desired, then the pointer map at this instruction needs |
| 915 | // to be adjusted manually. |
| 916 | } |
| 917 | } |
| 918 | } |
| 919 | } |
| 920 | } |
| 921 | |
| 922 | |
| 923 | bool RegisterAllocator::IsOutputRegisterOf(Instruction* instr, int index) { |
| 924 | for (size_t i = 0; i < instr->OutputCount(); i++) { |
| 925 | InstructionOperand* output = instr->OutputAt(i); |
| 926 | if (output->IsRegister() && output->index() == index) return true; |
| 927 | } |
| 928 | return false; |
| 929 | } |
| 930 | |
| 931 | |
| 932 | bool RegisterAllocator::IsOutputDoubleRegisterOf(Instruction* instr, |
| 933 | int index) { |
| 934 | for (size_t i = 0; i < instr->OutputCount(); i++) { |
| 935 | InstructionOperand* output = instr->OutputAt(i); |
| 936 | if (output->IsDoubleRegister() && output->index() == index) return true; |
| 937 | } |
| 938 | return false; |
| 939 | } |
| 940 | |
| 941 | |
| 942 | void RegisterAllocator::ProcessInstructions(BasicBlock* block, |
| 943 | BitVector* live) { |
| 944 | int block_start = block->first_instruction_index(); |
| 945 | |
| 946 | LifetimePosition block_start_position = |
| 947 | LifetimePosition::FromInstructionIndex(block_start); |
| 948 | |
| 949 | for (int index = block->last_instruction_index(); index >= block_start; |
| 950 | index--) { |
| 951 | LifetimePosition curr_position = |
| 952 | LifetimePosition::FromInstructionIndex(index); |
| 953 | |
| 954 | Instruction* instr = InstructionAt(index); |
| 955 | DCHECK(instr != NULL); |
| 956 | if (instr->IsGapMoves()) { |
| 957 | // Process the moves of the gap instruction, making their sources live. |
| 958 | GapInstruction* gap = code()->GapAt(index); |
| 959 | |
| 960 | // TODO(titzer): no need to create the parallel move if it doesn't exist. |
| 961 | ParallelMove* move = |
| 962 | gap->GetOrCreateParallelMove(GapInstruction::START, code_zone()); |
| 963 | const ZoneList<MoveOperands>* move_operands = move->move_operands(); |
| 964 | for (int i = 0; i < move_operands->length(); ++i) { |
| 965 | MoveOperands* cur = &move_operands->at(i); |
| 966 | if (cur->IsIgnored()) continue; |
| 967 | InstructionOperand* from = cur->source(); |
| 968 | InstructionOperand* to = cur->destination(); |
| 969 | InstructionOperand* hint = to; |
| 970 | if (to->IsUnallocated()) { |
| 971 | int to_vreg = UnallocatedOperand::cast(to)->virtual_register(); |
| 972 | LiveRange* to_range = LiveRangeFor(to_vreg); |
| 973 | if (to_range->is_phi()) { |
| 974 | if (to_range->is_non_loop_phi()) { |
| 975 | hint = to_range->current_hint_operand(); |
| 976 | } |
| 977 | } else { |
| 978 | if (live->Contains(to_vreg)) { |
| 979 | Define(curr_position, to, from); |
| 980 | live->Remove(to_vreg); |
| 981 | } else { |
| 982 | cur->Eliminate(); |
| 983 | continue; |
| 984 | } |
| 985 | } |
| 986 | } else { |
| 987 | Define(curr_position, to, from); |
| 988 | } |
| 989 | Use(block_start_position, curr_position, from, hint); |
| 990 | if (from->IsUnallocated()) { |
| 991 | live->Add(UnallocatedOperand::cast(from)->virtual_register()); |
| 992 | } |
| 993 | } |
| 994 | } else { |
| 995 | // Process output, inputs, and temps of this non-gap instruction. |
| 996 | for (size_t i = 0; i < instr->OutputCount(); i++) { |
| 997 | InstructionOperand* output = instr->OutputAt(i); |
| 998 | if (output->IsUnallocated()) { |
| 999 | int out_vreg = UnallocatedOperand::cast(output)->virtual_register(); |
| 1000 | live->Remove(out_vreg); |
| 1001 | } else if (output->IsConstant()) { |
| 1002 | int out_vreg = output->index(); |
| 1003 | live->Remove(out_vreg); |
| 1004 | } |
| 1005 | Define(curr_position, output, NULL); |
| 1006 | } |
| 1007 | |
| 1008 | if (instr->ClobbersRegisters()) { |
| 1009 | for (int i = 0; i < Register::kMaxNumAllocatableRegisters; ++i) { |
| 1010 | if (!IsOutputRegisterOf(instr, i)) { |
| 1011 | LiveRange* range = FixedLiveRangeFor(i); |
| 1012 | range->AddUseInterval(curr_position, curr_position.InstructionEnd(), |
| 1013 | zone()); |
| 1014 | } |
| 1015 | } |
| 1016 | } |
| 1017 | |
| 1018 | if (instr->ClobbersDoubleRegisters()) { |
| 1019 | for (int i = 0; i < DoubleRegister::NumAllocatableRegisters(); ++i) { |
| 1020 | if (!IsOutputDoubleRegisterOf(instr, i)) { |
| 1021 | LiveRange* range = FixedDoubleLiveRangeFor(i); |
| 1022 | range->AddUseInterval(curr_position, curr_position.InstructionEnd(), |
| 1023 | zone()); |
| 1024 | } |
| 1025 | } |
| 1026 | } |
| 1027 | |
| 1028 | for (size_t i = 0; i < instr->InputCount(); i++) { |
| 1029 | InstructionOperand* input = instr->InputAt(i); |
| 1030 | if (input->IsImmediate()) continue; // Ignore immediates. |
| 1031 | LifetimePosition use_pos; |
| 1032 | if (input->IsUnallocated() && |
| 1033 | UnallocatedOperand::cast(input)->IsUsedAtStart()) { |
| 1034 | use_pos = curr_position; |
| 1035 | } else { |
| 1036 | use_pos = curr_position.InstructionEnd(); |
| 1037 | } |
| 1038 | |
| 1039 | Use(block_start_position, use_pos, input, NULL); |
| 1040 | if (input->IsUnallocated()) { |
| 1041 | live->Add(UnallocatedOperand::cast(input)->virtual_register()); |
| 1042 | } |
| 1043 | } |
| 1044 | |
| 1045 | for (size_t i = 0; i < instr->TempCount(); i++) { |
| 1046 | InstructionOperand* temp = instr->TempAt(i); |
| 1047 | if (instr->ClobbersTemps()) { |
| 1048 | if (temp->IsRegister()) continue; |
| 1049 | if (temp->IsUnallocated()) { |
| 1050 | UnallocatedOperand* temp_unalloc = UnallocatedOperand::cast(temp); |
| 1051 | if (temp_unalloc->HasFixedPolicy()) { |
| 1052 | continue; |
| 1053 | } |
| 1054 | } |
| 1055 | } |
| 1056 | Use(block_start_position, curr_position.InstructionEnd(), temp, NULL); |
| 1057 | Define(curr_position, temp, NULL); |
| 1058 | } |
| 1059 | } |
| 1060 | } |
| 1061 | } |
| 1062 | |
| 1063 | |
| 1064 | void RegisterAllocator::ResolvePhis(BasicBlock* block) { |
| 1065 | for (BasicBlock::const_iterator i = block->begin(); i != block->end(); ++i) { |
| 1066 | Node* phi = *i; |
| 1067 | if (phi->opcode() != IrOpcode::kPhi) continue; |
| 1068 | |
| 1069 | UnallocatedOperand* phi_operand = |
| 1070 | new (code_zone()) UnallocatedOperand(UnallocatedOperand::NONE); |
| 1071 | phi_operand->set_virtual_register(phi->id()); |
| 1072 | |
| 1073 | int j = 0; |
| 1074 | Node::Inputs inputs = phi->inputs(); |
| 1075 | for (Node::Inputs::iterator iter(inputs.begin()); iter != inputs.end(); |
| 1076 | ++iter, ++j) { |
| 1077 | Node* op = *iter; |
| 1078 | // TODO(mstarzinger): Use a ValueInputIterator instead. |
| 1079 | if (j >= block->PredecessorCount()) continue; |
| 1080 | UnallocatedOperand* operand = |
| 1081 | new (code_zone()) UnallocatedOperand(UnallocatedOperand::ANY); |
| 1082 | operand->set_virtual_register(op->id()); |
| 1083 | BasicBlock* cur_block = block->PredecessorAt(j); |
| 1084 | // The gap move must be added without any special processing as in |
| 1085 | // the AddConstraintsGapMove. |
| 1086 | code()->AddGapMove(cur_block->last_instruction_index() - 1, operand, |
| 1087 | phi_operand); |
| 1088 | |
| 1089 | Instruction* branch = InstructionAt(cur_block->last_instruction_index()); |
| 1090 | DCHECK(!branch->HasPointerMap()); |
| 1091 | USE(branch); |
| 1092 | } |
| 1093 | |
| 1094 | LiveRange* live_range = LiveRangeFor(phi->id()); |
| 1095 | BlockStartInstruction* block_start = code()->GetBlockStart(block); |
| 1096 | block_start->GetOrCreateParallelMove(GapInstruction::START, code_zone()) |
| 1097 | ->AddMove(phi_operand, live_range->GetSpillOperand(), code_zone()); |
| 1098 | live_range->SetSpillStartIndex(block->first_instruction_index()); |
| 1099 | |
| 1100 | // We use the phi-ness of some nodes in some later heuristics. |
| 1101 | live_range->set_is_phi(true); |
| 1102 | if (!block->IsLoopHeader()) { |
| 1103 | live_range->set_is_non_loop_phi(true); |
| 1104 | } |
| 1105 | } |
| 1106 | } |
| 1107 | |
| 1108 | |
| 1109 | bool RegisterAllocator::Allocate() { |
| 1110 | assigned_registers_ = new (code_zone()) |
| 1111 | BitVector(Register::NumAllocatableRegisters(), code_zone()); |
| 1112 | assigned_double_registers_ = new (code_zone()) |
| 1113 | BitVector(DoubleRegister::NumAllocatableRegisters(), code_zone()); |
| 1114 | MeetRegisterConstraints(); |
| 1115 | if (!AllocationOk()) return false; |
| 1116 | ResolvePhis(); |
| 1117 | BuildLiveRanges(); |
| 1118 | AllocateGeneralRegisters(); |
| 1119 | if (!AllocationOk()) return false; |
| 1120 | AllocateDoubleRegisters(); |
| 1121 | if (!AllocationOk()) return false; |
| 1122 | PopulatePointerMaps(); |
| 1123 | ConnectRanges(); |
| 1124 | ResolveControlFlow(); |
| 1125 | code()->frame()->SetAllocatedRegisters(assigned_registers_); |
| 1126 | code()->frame()->SetAllocatedDoubleRegisters(assigned_double_registers_); |
| 1127 | return true; |
| 1128 | } |
| 1129 | |
| 1130 | |
| 1131 | void RegisterAllocator::MeetRegisterConstraints() { |
| 1132 | RegisterAllocatorPhase phase("L_Register constraints", this); |
| 1133 | for (int i = 0; i < code()->BasicBlockCount(); ++i) { |
| 1134 | MeetRegisterConstraints(code()->BlockAt(i)); |
| 1135 | if (!AllocationOk()) return; |
| 1136 | } |
| 1137 | } |
| 1138 | |
| 1139 | |
| 1140 | void RegisterAllocator::ResolvePhis() { |
| 1141 | RegisterAllocatorPhase phase("L_Resolve phis", this); |
| 1142 | |
| 1143 | // Process the blocks in reverse order. |
| 1144 | for (int i = code()->BasicBlockCount() - 1; i >= 0; --i) { |
| 1145 | ResolvePhis(code()->BlockAt(i)); |
| 1146 | } |
| 1147 | } |
| 1148 | |
| 1149 | |
| 1150 | void RegisterAllocator::ResolveControlFlow(LiveRange* range, BasicBlock* block, |
| 1151 | BasicBlock* pred) { |
| 1152 | LifetimePosition pred_end = |
| 1153 | LifetimePosition::FromInstructionIndex(pred->last_instruction_index()); |
| 1154 | LifetimePosition cur_start = |
| 1155 | LifetimePosition::FromInstructionIndex(block->first_instruction_index()); |
| 1156 | LiveRange* pred_cover = NULL; |
| 1157 | LiveRange* cur_cover = NULL; |
| 1158 | LiveRange* cur_range = range; |
| 1159 | while (cur_range != NULL && (cur_cover == NULL || pred_cover == NULL)) { |
| 1160 | if (cur_range->CanCover(cur_start)) { |
| 1161 | DCHECK(cur_cover == NULL); |
| 1162 | cur_cover = cur_range; |
| 1163 | } |
| 1164 | if (cur_range->CanCover(pred_end)) { |
| 1165 | DCHECK(pred_cover == NULL); |
| 1166 | pred_cover = cur_range; |
| 1167 | } |
| 1168 | cur_range = cur_range->next(); |
| 1169 | } |
| 1170 | |
| 1171 | if (cur_cover->IsSpilled()) return; |
| 1172 | DCHECK(pred_cover != NULL && cur_cover != NULL); |
| 1173 | if (pred_cover != cur_cover) { |
| 1174 | InstructionOperand* pred_op = |
| 1175 | pred_cover->CreateAssignedOperand(code_zone()); |
| 1176 | InstructionOperand* cur_op = cur_cover->CreateAssignedOperand(code_zone()); |
| 1177 | if (!pred_op->Equals(cur_op)) { |
| 1178 | GapInstruction* gap = NULL; |
| 1179 | if (block->PredecessorCount() == 1) { |
| 1180 | gap = code()->GapAt(block->first_instruction_index()); |
| 1181 | } else { |
| 1182 | DCHECK(pred->SuccessorCount() == 1); |
| 1183 | gap = GetLastGap(pred); |
| 1184 | |
| 1185 | Instruction* branch = InstructionAt(pred->last_instruction_index()); |
| 1186 | DCHECK(!branch->HasPointerMap()); |
| 1187 | USE(branch); |
| 1188 | } |
| 1189 | gap->GetOrCreateParallelMove(GapInstruction::START, code_zone()) |
| 1190 | ->AddMove(pred_op, cur_op, code_zone()); |
| 1191 | } |
| 1192 | } |
| 1193 | } |
| 1194 | |
| 1195 | |
| 1196 | ParallelMove* RegisterAllocator::GetConnectingParallelMove( |
| 1197 | LifetimePosition pos) { |
| 1198 | int index = pos.InstructionIndex(); |
| 1199 | if (code()->IsGapAt(index)) { |
| 1200 | GapInstruction* gap = code()->GapAt(index); |
| 1201 | return gap->GetOrCreateParallelMove( |
| 1202 | pos.IsInstructionStart() ? GapInstruction::START : GapInstruction::END, |
| 1203 | code_zone()); |
| 1204 | } |
| 1205 | int gap_pos = pos.IsInstructionStart() ? (index - 1) : (index + 1); |
| 1206 | return code()->GapAt(gap_pos)->GetOrCreateParallelMove( |
| 1207 | (gap_pos < index) ? GapInstruction::AFTER : GapInstruction::BEFORE, |
| 1208 | code_zone()); |
| 1209 | } |
| 1210 | |
| 1211 | |
| 1212 | BasicBlock* RegisterAllocator::GetBlock(LifetimePosition pos) { |
| 1213 | return code()->GetBasicBlock(pos.InstructionIndex()); |
| 1214 | } |
| 1215 | |
| 1216 | |
| 1217 | void RegisterAllocator::ConnectRanges() { |
| 1218 | RegisterAllocatorPhase phase("L_Connect ranges", this); |
| 1219 | for (int i = 0; i < live_ranges()->length(); ++i) { |
| 1220 | LiveRange* first_range = live_ranges()->at(i); |
| 1221 | if (first_range == NULL || first_range->parent() != NULL) continue; |
| 1222 | |
| 1223 | LiveRange* second_range = first_range->next(); |
| 1224 | while (second_range != NULL) { |
| 1225 | LifetimePosition pos = second_range->Start(); |
| 1226 | |
| 1227 | if (!second_range->IsSpilled()) { |
| 1228 | // Add gap move if the two live ranges touch and there is no block |
| 1229 | // boundary. |
| 1230 | if (first_range->End().Value() == pos.Value()) { |
| 1231 | bool should_insert = true; |
| 1232 | if (IsBlockBoundary(pos)) { |
| 1233 | should_insert = CanEagerlyResolveControlFlow(GetBlock(pos)); |
| 1234 | } |
| 1235 | if (should_insert) { |
| 1236 | ParallelMove* move = GetConnectingParallelMove(pos); |
| 1237 | InstructionOperand* prev_operand = |
| 1238 | first_range->CreateAssignedOperand(code_zone()); |
| 1239 | InstructionOperand* cur_operand = |
| 1240 | second_range->CreateAssignedOperand(code_zone()); |
| 1241 | move->AddMove(prev_operand, cur_operand, code_zone()); |
| 1242 | } |
| 1243 | } |
| 1244 | } |
| 1245 | |
| 1246 | first_range = second_range; |
| 1247 | second_range = second_range->next(); |
| 1248 | } |
| 1249 | } |
| 1250 | } |
| 1251 | |
| 1252 | |
| 1253 | bool RegisterAllocator::CanEagerlyResolveControlFlow(BasicBlock* block) const { |
| 1254 | if (block->PredecessorCount() != 1) return false; |
| 1255 | return block->PredecessorAt(0)->rpo_number_ == block->rpo_number_ - 1; |
| 1256 | } |
| 1257 | |
| 1258 | |
| 1259 | void RegisterAllocator::ResolveControlFlow() { |
| 1260 | RegisterAllocatorPhase phase("L_Resolve control flow", this); |
| 1261 | for (int block_id = 1; block_id < code()->BasicBlockCount(); ++block_id) { |
| 1262 | BasicBlock* block = code()->BlockAt(block_id); |
| 1263 | if (CanEagerlyResolveControlFlow(block)) continue; |
| 1264 | BitVector* live = live_in_sets_[block->rpo_number_]; |
| 1265 | BitVector::Iterator iterator(live); |
| 1266 | while (!iterator.Done()) { |
| 1267 | int operand_index = iterator.Current(); |
| 1268 | BasicBlock::Predecessors predecessors = block->predecessors(); |
| 1269 | for (BasicBlock::Predecessors::iterator i = predecessors.begin(); |
| 1270 | i != predecessors.end(); ++i) { |
| 1271 | BasicBlock* cur = *i; |
| 1272 | LiveRange* cur_range = LiveRangeFor(operand_index); |
| 1273 | ResolveControlFlow(cur_range, block, cur); |
| 1274 | } |
| 1275 | iterator.Advance(); |
| 1276 | } |
| 1277 | } |
| 1278 | } |
| 1279 | |
| 1280 | |
| 1281 | void RegisterAllocator::BuildLiveRanges() { |
| 1282 | RegisterAllocatorPhase phase("L_Build live ranges", this); |
| 1283 | InitializeLivenessAnalysis(); |
| 1284 | // Process the blocks in reverse order. |
| 1285 | for (int block_id = code()->BasicBlockCount() - 1; block_id >= 0; |
| 1286 | --block_id) { |
| 1287 | BasicBlock* block = code()->BlockAt(block_id); |
| 1288 | BitVector* live = ComputeLiveOut(block); |
| 1289 | // Initially consider all live_out values live for the entire block. We |
| 1290 | // will shorten these intervals if necessary. |
| 1291 | AddInitialIntervals(block, live); |
| 1292 | |
| 1293 | // Process the instructions in reverse order, generating and killing |
| 1294 | // live values. |
| 1295 | ProcessInstructions(block, live); |
| 1296 | // All phi output operands are killed by this block. |
| 1297 | for (BasicBlock::const_iterator i = block->begin(); i != block->end(); |
| 1298 | ++i) { |
| 1299 | Node* phi = *i; |
| 1300 | if (phi->opcode() != IrOpcode::kPhi) continue; |
| 1301 | |
| 1302 | // The live range interval already ends at the first instruction of the |
| 1303 | // block. |
| 1304 | live->Remove(phi->id()); |
| 1305 | |
| 1306 | InstructionOperand* hint = NULL; |
| 1307 | InstructionOperand* phi_operand = NULL; |
| 1308 | GapInstruction* gap = GetLastGap(block->PredecessorAt(0)); |
| 1309 | |
| 1310 | // TODO(titzer): no need to create the parallel move if it doesn't exit. |
| 1311 | ParallelMove* move = |
| 1312 | gap->GetOrCreateParallelMove(GapInstruction::START, code_zone()); |
| 1313 | for (int j = 0; j < move->move_operands()->length(); ++j) { |
| 1314 | InstructionOperand* to = move->move_operands()->at(j).destination(); |
| 1315 | if (to->IsUnallocated() && |
| 1316 | UnallocatedOperand::cast(to)->virtual_register() == phi->id()) { |
| 1317 | hint = move->move_operands()->at(j).source(); |
| 1318 | phi_operand = to; |
| 1319 | break; |
| 1320 | } |
| 1321 | } |
| 1322 | DCHECK(hint != NULL); |
| 1323 | |
| 1324 | LifetimePosition block_start = LifetimePosition::FromInstructionIndex( |
| 1325 | block->first_instruction_index()); |
| 1326 | Define(block_start, phi_operand, hint); |
| 1327 | } |
| 1328 | |
| 1329 | // Now live is live_in for this block except not including values live |
| 1330 | // out on backward successor edges. |
| 1331 | live_in_sets_[block_id] = live; |
| 1332 | |
| 1333 | if (block->IsLoopHeader()) { |
| 1334 | // Add a live range stretching from the first loop instruction to the last |
| 1335 | // for each value live on entry to the header. |
| 1336 | BitVector::Iterator iterator(live); |
| 1337 | LifetimePosition start = LifetimePosition::FromInstructionIndex( |
| 1338 | block->first_instruction_index()); |
| 1339 | int end_index = |
| 1340 | code()->BlockAt(block->loop_end_)->last_instruction_index(); |
| 1341 | LifetimePosition end = |
| 1342 | LifetimePosition::FromInstructionIndex(end_index).NextInstruction(); |
| 1343 | while (!iterator.Done()) { |
| 1344 | int operand_index = iterator.Current(); |
| 1345 | LiveRange* range = LiveRangeFor(operand_index); |
| 1346 | range->EnsureInterval(start, end, zone()); |
| 1347 | iterator.Advance(); |
| 1348 | } |
| 1349 | |
| 1350 | // Insert all values into the live in sets of all blocks in the loop. |
| 1351 | for (int i = block->rpo_number_ + 1; i < block->loop_end_; ++i) { |
| 1352 | live_in_sets_[i]->Union(*live); |
| 1353 | } |
| 1354 | } |
| 1355 | |
| 1356 | #ifdef DEBUG |
| 1357 | if (block_id == 0) { |
| 1358 | BitVector::Iterator iterator(live); |
| 1359 | bool found = false; |
| 1360 | while (!iterator.Done()) { |
| 1361 | found = true; |
| 1362 | int operand_index = iterator.Current(); |
| 1363 | PrintF("Register allocator error: live v%d reached first block.\n", |
| 1364 | operand_index); |
| 1365 | LiveRange* range = LiveRangeFor(operand_index); |
| 1366 | PrintF(" (first use is at %d)\n", range->first_pos()->pos().Value()); |
| 1367 | CompilationInfo* info = code()->linkage()->info(); |
| 1368 | if (info->IsStub()) { |
| 1369 | if (info->code_stub() == NULL) { |
| 1370 | PrintF("\n"); |
| 1371 | } else { |
| 1372 | CodeStub::Major major_key = info->code_stub()->MajorKey(); |
| 1373 | PrintF(" (function: %s)\n", CodeStub::MajorName(major_key, false)); |
| 1374 | } |
| 1375 | } else { |
| 1376 | DCHECK(info->IsOptimizing()); |
| 1377 | AllowHandleDereference allow_deref; |
| 1378 | PrintF(" (function: %s)\n", |
| 1379 | info->function()->debug_name()->ToCString().get()); |
| 1380 | } |
| 1381 | iterator.Advance(); |
| 1382 | } |
| 1383 | DCHECK(!found); |
| 1384 | } |
| 1385 | #endif |
| 1386 | } |
| 1387 | |
| 1388 | for (int i = 0; i < live_ranges_.length(); ++i) { |
| 1389 | if (live_ranges_[i] != NULL) { |
| 1390 | live_ranges_[i]->kind_ = RequiredRegisterKind(live_ranges_[i]->id()); |
| 1391 | |
| 1392 | // TODO(bmeurer): This is a horrible hack to make sure that for constant |
| 1393 | // live ranges, every use requires the constant to be in a register. |
| 1394 | // Without this hack, all uses with "any" policy would get the constant |
| 1395 | // operand assigned. |
| 1396 | LiveRange* range = live_ranges_[i]; |
| 1397 | if (range->HasAllocatedSpillOperand() && |
| 1398 | range->GetSpillOperand()->IsConstant()) { |
| 1399 | for (UsePosition* pos = range->first_pos(); pos != NULL; |
| 1400 | pos = pos->next_) { |
| 1401 | pos->register_beneficial_ = true; |
| 1402 | pos->requires_reg_ = true; |
| 1403 | } |
| 1404 | } |
| 1405 | } |
| 1406 | } |
| 1407 | } |
| 1408 | |
| 1409 | |
| 1410 | bool RegisterAllocator::SafePointsAreInOrder() const { |
| 1411 | int safe_point = 0; |
| 1412 | const PointerMapDeque* pointer_maps = code()->pointer_maps(); |
| 1413 | for (PointerMapDeque::const_iterator it = pointer_maps->begin(); |
| 1414 | it != pointer_maps->end(); ++it) { |
| 1415 | PointerMap* map = *it; |
| 1416 | if (safe_point > map->instruction_position()) return false; |
| 1417 | safe_point = map->instruction_position(); |
| 1418 | } |
| 1419 | return true; |
| 1420 | } |
| 1421 | |
| 1422 | |
| 1423 | void RegisterAllocator::PopulatePointerMaps() { |
| 1424 | RegisterAllocatorPhase phase("L_Populate pointer maps", this); |
| 1425 | |
| 1426 | DCHECK(SafePointsAreInOrder()); |
| 1427 | |
| 1428 | // Iterate over all safe point positions and record a pointer |
| 1429 | // for all spilled live ranges at this point. |
| 1430 | int last_range_start = 0; |
| 1431 | const PointerMapDeque* pointer_maps = code()->pointer_maps(); |
| 1432 | PointerMapDeque::const_iterator first_it = pointer_maps->begin(); |
| 1433 | for (int range_idx = 0; range_idx < live_ranges()->length(); ++range_idx) { |
| 1434 | LiveRange* range = live_ranges()->at(range_idx); |
| 1435 | if (range == NULL) continue; |
| 1436 | // Iterate over the first parts of multi-part live ranges. |
| 1437 | if (range->parent() != NULL) continue; |
| 1438 | // Skip non-reference values. |
| 1439 | if (!HasTaggedValue(range->id())) continue; |
| 1440 | // Skip empty live ranges. |
| 1441 | if (range->IsEmpty()) continue; |
| 1442 | |
| 1443 | // Find the extent of the range and its children. |
| 1444 | int start = range->Start().InstructionIndex(); |
| 1445 | int end = 0; |
| 1446 | for (LiveRange* cur = range; cur != NULL; cur = cur->next()) { |
| 1447 | LifetimePosition this_end = cur->End(); |
| 1448 | if (this_end.InstructionIndex() > end) end = this_end.InstructionIndex(); |
| 1449 | DCHECK(cur->Start().InstructionIndex() >= start); |
| 1450 | } |
| 1451 | |
| 1452 | // Most of the ranges are in order, but not all. Keep an eye on when they |
| 1453 | // step backwards and reset the first_it so we don't miss any safe points. |
| 1454 | if (start < last_range_start) first_it = pointer_maps->begin(); |
| 1455 | last_range_start = start; |
| 1456 | |
| 1457 | // Step across all the safe points that are before the start of this range, |
| 1458 | // recording how far we step in order to save doing this for the next range. |
| 1459 | for (; first_it != pointer_maps->end(); ++first_it) { |
| 1460 | PointerMap* map = *first_it; |
| 1461 | if (map->instruction_position() >= start) break; |
| 1462 | } |
| 1463 | |
| 1464 | // Step through the safe points to see whether they are in the range. |
| 1465 | for (PointerMapDeque::const_iterator it = first_it; |
| 1466 | it != pointer_maps->end(); ++it) { |
| 1467 | PointerMap* map = *it; |
| 1468 | int safe_point = map->instruction_position(); |
| 1469 | |
| 1470 | // The safe points are sorted so we can stop searching here. |
| 1471 | if (safe_point - 1 > end) break; |
| 1472 | |
| 1473 | // Advance to the next active range that covers the current |
| 1474 | // safe point position. |
| 1475 | LifetimePosition safe_point_pos = |
| 1476 | LifetimePosition::FromInstructionIndex(safe_point); |
| 1477 | LiveRange* cur = range; |
| 1478 | while (cur != NULL && !cur->Covers(safe_point_pos)) { |
| 1479 | cur = cur->next(); |
| 1480 | } |
| 1481 | if (cur == NULL) continue; |
| 1482 | |
| 1483 | // Check if the live range is spilled and the safe point is after |
| 1484 | // the spill position. |
| 1485 | if (range->HasAllocatedSpillOperand() && |
| 1486 | safe_point >= range->spill_start_index() && |
| 1487 | !range->GetSpillOperand()->IsConstant()) { |
| 1488 | TraceAlloc("Pointer for range %d (spilled at %d) at safe point %d\n", |
| 1489 | range->id(), range->spill_start_index(), safe_point); |
| 1490 | map->RecordPointer(range->GetSpillOperand(), code_zone()); |
| 1491 | } |
| 1492 | |
| 1493 | if (!cur->IsSpilled()) { |
| 1494 | TraceAlloc( |
| 1495 | "Pointer in register for range %d (start at %d) " |
| 1496 | "at safe point %d\n", |
| 1497 | cur->id(), cur->Start().Value(), safe_point); |
| 1498 | InstructionOperand* operand = cur->CreateAssignedOperand(code_zone()); |
| 1499 | DCHECK(!operand->IsStackSlot()); |
| 1500 | map->RecordPointer(operand, code_zone()); |
| 1501 | } |
| 1502 | } |
| 1503 | } |
| 1504 | } |
| 1505 | |
| 1506 | |
| 1507 | void RegisterAllocator::AllocateGeneralRegisters() { |
| 1508 | RegisterAllocatorPhase phase("L_Allocate general registers", this); |
| 1509 | num_registers_ = Register::NumAllocatableRegisters(); |
| 1510 | mode_ = GENERAL_REGISTERS; |
| 1511 | AllocateRegisters(); |
| 1512 | } |
| 1513 | |
| 1514 | |
| 1515 | void RegisterAllocator::AllocateDoubleRegisters() { |
| 1516 | RegisterAllocatorPhase phase("L_Allocate double registers", this); |
| 1517 | num_registers_ = DoubleRegister::NumAllocatableRegisters(); |
| 1518 | mode_ = DOUBLE_REGISTERS; |
| 1519 | AllocateRegisters(); |
| 1520 | } |
| 1521 | |
| 1522 | |
| 1523 | void RegisterAllocator::AllocateRegisters() { |
| 1524 | DCHECK(unhandled_live_ranges_.is_empty()); |
| 1525 | |
| 1526 | for (int i = 0; i < live_ranges_.length(); ++i) { |
| 1527 | if (live_ranges_[i] != NULL) { |
| 1528 | if (live_ranges_[i]->Kind() == mode_) { |
| 1529 | AddToUnhandledUnsorted(live_ranges_[i]); |
| 1530 | } |
| 1531 | } |
| 1532 | } |
| 1533 | SortUnhandled(); |
| 1534 | DCHECK(UnhandledIsSorted()); |
| 1535 | |
| 1536 | DCHECK(reusable_slots_.is_empty()); |
| 1537 | DCHECK(active_live_ranges_.is_empty()); |
| 1538 | DCHECK(inactive_live_ranges_.is_empty()); |
| 1539 | |
| 1540 | if (mode_ == DOUBLE_REGISTERS) { |
| 1541 | for (int i = 0; i < DoubleRegister::NumAllocatableRegisters(); ++i) { |
| 1542 | LiveRange* current = fixed_double_live_ranges_.at(i); |
| 1543 | if (current != NULL) { |
| 1544 | AddToInactive(current); |
| 1545 | } |
| 1546 | } |
| 1547 | } else { |
| 1548 | DCHECK(mode_ == GENERAL_REGISTERS); |
| 1549 | for (int i = 0; i < fixed_live_ranges_.length(); ++i) { |
| 1550 | LiveRange* current = fixed_live_ranges_.at(i); |
| 1551 | if (current != NULL) { |
| 1552 | AddToInactive(current); |
| 1553 | } |
| 1554 | } |
| 1555 | } |
| 1556 | |
| 1557 | while (!unhandled_live_ranges_.is_empty()) { |
| 1558 | DCHECK(UnhandledIsSorted()); |
| 1559 | LiveRange* current = unhandled_live_ranges_.RemoveLast(); |
| 1560 | DCHECK(UnhandledIsSorted()); |
| 1561 | LifetimePosition position = current->Start(); |
| 1562 | #ifdef DEBUG |
| 1563 | allocation_finger_ = position; |
| 1564 | #endif |
| 1565 | TraceAlloc("Processing interval %d start=%d\n", current->id(), |
| 1566 | position.Value()); |
| 1567 | |
| 1568 | if (current->HasAllocatedSpillOperand()) { |
| 1569 | TraceAlloc("Live range %d already has a spill operand\n", current->id()); |
| 1570 | LifetimePosition next_pos = position; |
| 1571 | if (code()->IsGapAt(next_pos.InstructionIndex())) { |
| 1572 | next_pos = next_pos.NextInstruction(); |
| 1573 | } |
| 1574 | UsePosition* pos = current->NextUsePositionRegisterIsBeneficial(next_pos); |
| 1575 | // If the range already has a spill operand and it doesn't need a |
| 1576 | // register immediately, split it and spill the first part of the range. |
| 1577 | if (pos == NULL) { |
| 1578 | Spill(current); |
| 1579 | continue; |
| 1580 | } else if (pos->pos().Value() > |
| 1581 | current->Start().NextInstruction().Value()) { |
| 1582 | // Do not spill live range eagerly if use position that can benefit from |
| 1583 | // the register is too close to the start of live range. |
| 1584 | SpillBetween(current, current->Start(), pos->pos()); |
| 1585 | if (!AllocationOk()) return; |
| 1586 | DCHECK(UnhandledIsSorted()); |
| 1587 | continue; |
| 1588 | } |
| 1589 | } |
| 1590 | |
| 1591 | for (int i = 0; i < active_live_ranges_.length(); ++i) { |
| 1592 | LiveRange* cur_active = active_live_ranges_.at(i); |
| 1593 | if (cur_active->End().Value() <= position.Value()) { |
| 1594 | ActiveToHandled(cur_active); |
| 1595 | --i; // The live range was removed from the list of active live ranges. |
| 1596 | } else if (!cur_active->Covers(position)) { |
| 1597 | ActiveToInactive(cur_active); |
| 1598 | --i; // The live range was removed from the list of active live ranges. |
| 1599 | } |
| 1600 | } |
| 1601 | |
| 1602 | for (int i = 0; i < inactive_live_ranges_.length(); ++i) { |
| 1603 | LiveRange* cur_inactive = inactive_live_ranges_.at(i); |
| 1604 | if (cur_inactive->End().Value() <= position.Value()) { |
| 1605 | InactiveToHandled(cur_inactive); |
| 1606 | --i; // Live range was removed from the list of inactive live ranges. |
| 1607 | } else if (cur_inactive->Covers(position)) { |
| 1608 | InactiveToActive(cur_inactive); |
| 1609 | --i; // Live range was removed from the list of inactive live ranges. |
| 1610 | } |
| 1611 | } |
| 1612 | |
| 1613 | DCHECK(!current->HasRegisterAssigned() && !current->IsSpilled()); |
| 1614 | |
| 1615 | bool result = TryAllocateFreeReg(current); |
| 1616 | if (!AllocationOk()) return; |
| 1617 | |
| 1618 | if (!result) AllocateBlockedReg(current); |
| 1619 | if (!AllocationOk()) return; |
| 1620 | |
| 1621 | if (current->HasRegisterAssigned()) { |
| 1622 | AddToActive(current); |
| 1623 | } |
| 1624 | } |
| 1625 | |
| 1626 | reusable_slots_.Rewind(0); |
| 1627 | active_live_ranges_.Rewind(0); |
| 1628 | inactive_live_ranges_.Rewind(0); |
| 1629 | } |
| 1630 | |
| 1631 | |
| 1632 | const char* RegisterAllocator::RegisterName(int allocation_index) { |
| 1633 | if (mode_ == GENERAL_REGISTERS) { |
| 1634 | return Register::AllocationIndexToString(allocation_index); |
| 1635 | } else { |
| 1636 | return DoubleRegister::AllocationIndexToString(allocation_index); |
| 1637 | } |
| 1638 | } |
| 1639 | |
| 1640 | |
| 1641 | void RegisterAllocator::TraceAlloc(const char* msg, ...) { |
| 1642 | if (FLAG_trace_alloc) { |
| 1643 | va_list arguments; |
| 1644 | va_start(arguments, msg); |
| 1645 | base::OS::VPrint(msg, arguments); |
| 1646 | va_end(arguments); |
| 1647 | } |
| 1648 | } |
| 1649 | |
| 1650 | |
| 1651 | bool RegisterAllocator::HasTaggedValue(int virtual_register) const { |
| 1652 | return code()->IsReference(virtual_register); |
| 1653 | } |
| 1654 | |
| 1655 | |
| 1656 | RegisterKind RegisterAllocator::RequiredRegisterKind( |
| 1657 | int virtual_register) const { |
| 1658 | return (code()->IsDouble(virtual_register)) ? DOUBLE_REGISTERS |
| 1659 | : GENERAL_REGISTERS; |
| 1660 | } |
| 1661 | |
| 1662 | |
| 1663 | void RegisterAllocator::AddToActive(LiveRange* range) { |
| 1664 | TraceAlloc("Add live range %d to active\n", range->id()); |
| 1665 | active_live_ranges_.Add(range, zone()); |
| 1666 | } |
| 1667 | |
| 1668 | |
| 1669 | void RegisterAllocator::AddToInactive(LiveRange* range) { |
| 1670 | TraceAlloc("Add live range %d to inactive\n", range->id()); |
| 1671 | inactive_live_ranges_.Add(range, zone()); |
| 1672 | } |
| 1673 | |
| 1674 | |
| 1675 | void RegisterAllocator::AddToUnhandledSorted(LiveRange* range) { |
| 1676 | if (range == NULL || range->IsEmpty()) return; |
| 1677 | DCHECK(!range->HasRegisterAssigned() && !range->IsSpilled()); |
| 1678 | DCHECK(allocation_finger_.Value() <= range->Start().Value()); |
| 1679 | for (int i = unhandled_live_ranges_.length() - 1; i >= 0; --i) { |
| 1680 | LiveRange* cur_range = unhandled_live_ranges_.at(i); |
| 1681 | if (range->ShouldBeAllocatedBefore(cur_range)) { |
| 1682 | TraceAlloc("Add live range %d to unhandled at %d\n", range->id(), i + 1); |
| 1683 | unhandled_live_ranges_.InsertAt(i + 1, range, zone()); |
| 1684 | DCHECK(UnhandledIsSorted()); |
| 1685 | return; |
| 1686 | } |
| 1687 | } |
| 1688 | TraceAlloc("Add live range %d to unhandled at start\n", range->id()); |
| 1689 | unhandled_live_ranges_.InsertAt(0, range, zone()); |
| 1690 | DCHECK(UnhandledIsSorted()); |
| 1691 | } |
| 1692 | |
| 1693 | |
| 1694 | void RegisterAllocator::AddToUnhandledUnsorted(LiveRange* range) { |
| 1695 | if (range == NULL || range->IsEmpty()) return; |
| 1696 | DCHECK(!range->HasRegisterAssigned() && !range->IsSpilled()); |
| 1697 | TraceAlloc("Add live range %d to unhandled unsorted at end\n", range->id()); |
| 1698 | unhandled_live_ranges_.Add(range, zone()); |
| 1699 | } |
| 1700 | |
| 1701 | |
| 1702 | static int UnhandledSortHelper(LiveRange* const* a, LiveRange* const* b) { |
| 1703 | DCHECK(!(*a)->ShouldBeAllocatedBefore(*b) || |
| 1704 | !(*b)->ShouldBeAllocatedBefore(*a)); |
| 1705 | if ((*a)->ShouldBeAllocatedBefore(*b)) return 1; |
| 1706 | if ((*b)->ShouldBeAllocatedBefore(*a)) return -1; |
| 1707 | return (*a)->id() - (*b)->id(); |
| 1708 | } |
| 1709 | |
| 1710 | |
| 1711 | // Sort the unhandled live ranges so that the ranges to be processed first are |
| 1712 | // at the end of the array list. This is convenient for the register allocation |
| 1713 | // algorithm because it is efficient to remove elements from the end. |
| 1714 | void RegisterAllocator::SortUnhandled() { |
| 1715 | TraceAlloc("Sort unhandled\n"); |
| 1716 | unhandled_live_ranges_.Sort(&UnhandledSortHelper); |
| 1717 | } |
| 1718 | |
| 1719 | |
| 1720 | bool RegisterAllocator::UnhandledIsSorted() { |
| 1721 | int len = unhandled_live_ranges_.length(); |
| 1722 | for (int i = 1; i < len; i++) { |
| 1723 | LiveRange* a = unhandled_live_ranges_.at(i - 1); |
| 1724 | LiveRange* b = unhandled_live_ranges_.at(i); |
| 1725 | if (a->Start().Value() < b->Start().Value()) return false; |
| 1726 | } |
| 1727 | return true; |
| 1728 | } |
| 1729 | |
| 1730 | |
| 1731 | void RegisterAllocator::FreeSpillSlot(LiveRange* range) { |
| 1732 | // Check that we are the last range. |
| 1733 | if (range->next() != NULL) return; |
| 1734 | |
| 1735 | if (!range->TopLevel()->HasAllocatedSpillOperand()) return; |
| 1736 | |
| 1737 | InstructionOperand* spill_operand = range->TopLevel()->GetSpillOperand(); |
| 1738 | if (spill_operand->IsConstant()) return; |
| 1739 | if (spill_operand->index() >= 0) { |
| 1740 | reusable_slots_.Add(range, zone()); |
| 1741 | } |
| 1742 | } |
| 1743 | |
| 1744 | |
| 1745 | InstructionOperand* RegisterAllocator::TryReuseSpillSlot(LiveRange* range) { |
| 1746 | if (reusable_slots_.is_empty()) return NULL; |
| 1747 | if (reusable_slots_.first()->End().Value() > |
| 1748 | range->TopLevel()->Start().Value()) { |
| 1749 | return NULL; |
| 1750 | } |
| 1751 | InstructionOperand* result = |
| 1752 | reusable_slots_.first()->TopLevel()->GetSpillOperand(); |
| 1753 | reusable_slots_.Remove(0); |
| 1754 | return result; |
| 1755 | } |
| 1756 | |
| 1757 | |
| 1758 | void RegisterAllocator::ActiveToHandled(LiveRange* range) { |
| 1759 | DCHECK(active_live_ranges_.Contains(range)); |
| 1760 | active_live_ranges_.RemoveElement(range); |
| 1761 | TraceAlloc("Moving live range %d from active to handled\n", range->id()); |
| 1762 | FreeSpillSlot(range); |
| 1763 | } |
| 1764 | |
| 1765 | |
| 1766 | void RegisterAllocator::ActiveToInactive(LiveRange* range) { |
| 1767 | DCHECK(active_live_ranges_.Contains(range)); |
| 1768 | active_live_ranges_.RemoveElement(range); |
| 1769 | inactive_live_ranges_.Add(range, zone()); |
| 1770 | TraceAlloc("Moving live range %d from active to inactive\n", range->id()); |
| 1771 | } |
| 1772 | |
| 1773 | |
| 1774 | void RegisterAllocator::InactiveToHandled(LiveRange* range) { |
| 1775 | DCHECK(inactive_live_ranges_.Contains(range)); |
| 1776 | inactive_live_ranges_.RemoveElement(range); |
| 1777 | TraceAlloc("Moving live range %d from inactive to handled\n", range->id()); |
| 1778 | FreeSpillSlot(range); |
| 1779 | } |
| 1780 | |
| 1781 | |
| 1782 | void RegisterAllocator::InactiveToActive(LiveRange* range) { |
| 1783 | DCHECK(inactive_live_ranges_.Contains(range)); |
| 1784 | inactive_live_ranges_.RemoveElement(range); |
| 1785 | active_live_ranges_.Add(range, zone()); |
| 1786 | TraceAlloc("Moving live range %d from inactive to active\n", range->id()); |
| 1787 | } |
| 1788 | |
| 1789 | |
| 1790 | // TryAllocateFreeReg and AllocateBlockedReg assume this |
| 1791 | // when allocating local arrays. |
| 1792 | STATIC_ASSERT(DoubleRegister::kMaxNumAllocatableRegisters >= |
| 1793 | Register::kMaxNumAllocatableRegisters); |
| 1794 | |
| 1795 | |
| 1796 | bool RegisterAllocator::TryAllocateFreeReg(LiveRange* current) { |
| 1797 | LifetimePosition free_until_pos[DoubleRegister::kMaxNumAllocatableRegisters]; |
| 1798 | |
| 1799 | for (int i = 0; i < num_registers_; i++) { |
| 1800 | free_until_pos[i] = LifetimePosition::MaxPosition(); |
| 1801 | } |
| 1802 | |
| 1803 | for (int i = 0; i < active_live_ranges_.length(); ++i) { |
| 1804 | LiveRange* cur_active = active_live_ranges_.at(i); |
| 1805 | free_until_pos[cur_active->assigned_register()] = |
| 1806 | LifetimePosition::FromInstructionIndex(0); |
| 1807 | } |
| 1808 | |
| 1809 | for (int i = 0; i < inactive_live_ranges_.length(); ++i) { |
| 1810 | LiveRange* cur_inactive = inactive_live_ranges_.at(i); |
| 1811 | DCHECK(cur_inactive->End().Value() > current->Start().Value()); |
| 1812 | LifetimePosition next_intersection = |
| 1813 | cur_inactive->FirstIntersection(current); |
| 1814 | if (!next_intersection.IsValid()) continue; |
| 1815 | int cur_reg = cur_inactive->assigned_register(); |
| 1816 | free_until_pos[cur_reg] = Min(free_until_pos[cur_reg], next_intersection); |
| 1817 | } |
| 1818 | |
| 1819 | InstructionOperand* hint = current->FirstHint(); |
| 1820 | if (hint != NULL && (hint->IsRegister() || hint->IsDoubleRegister())) { |
| 1821 | int register_index = hint->index(); |
| 1822 | TraceAlloc( |
| 1823 | "Found reg hint %s (free until [%d) for live range %d (end %d[).\n", |
| 1824 | RegisterName(register_index), free_until_pos[register_index].Value(), |
| 1825 | current->id(), current->End().Value()); |
| 1826 | |
| 1827 | // The desired register is free until the end of the current live range. |
| 1828 | if (free_until_pos[register_index].Value() >= current->End().Value()) { |
| 1829 | TraceAlloc("Assigning preferred reg %s to live range %d\n", |
| 1830 | RegisterName(register_index), current->id()); |
| 1831 | SetLiveRangeAssignedRegister(current, register_index); |
| 1832 | return true; |
| 1833 | } |
| 1834 | } |
| 1835 | |
| 1836 | // Find the register which stays free for the longest time. |
| 1837 | int reg = 0; |
| 1838 | for (int i = 1; i < RegisterCount(); ++i) { |
| 1839 | if (free_until_pos[i].Value() > free_until_pos[reg].Value()) { |
| 1840 | reg = i; |
| 1841 | } |
| 1842 | } |
| 1843 | |
| 1844 | LifetimePosition pos = free_until_pos[reg]; |
| 1845 | |
| 1846 | if (pos.Value() <= current->Start().Value()) { |
| 1847 | // All registers are blocked. |
| 1848 | return false; |
| 1849 | } |
| 1850 | |
| 1851 | if (pos.Value() < current->End().Value()) { |
| 1852 | // Register reg is available at the range start but becomes blocked before |
| 1853 | // the range end. Split current at position where it becomes blocked. |
| 1854 | LiveRange* tail = SplitRangeAt(current, pos); |
| 1855 | if (!AllocationOk()) return false; |
| 1856 | AddToUnhandledSorted(tail); |
| 1857 | } |
| 1858 | |
| 1859 | |
| 1860 | // Register reg is available at the range start and is free until |
| 1861 | // the range end. |
| 1862 | DCHECK(pos.Value() >= current->End().Value()); |
| 1863 | TraceAlloc("Assigning free reg %s to live range %d\n", RegisterName(reg), |
| 1864 | current->id()); |
| 1865 | SetLiveRangeAssignedRegister(current, reg); |
| 1866 | |
| 1867 | return true; |
| 1868 | } |
| 1869 | |
| 1870 | |
| 1871 | void RegisterAllocator::AllocateBlockedReg(LiveRange* current) { |
| 1872 | UsePosition* register_use = current->NextRegisterPosition(current->Start()); |
| 1873 | if (register_use == NULL) { |
| 1874 | // There is no use in the current live range that requires a register. |
| 1875 | // We can just spill it. |
| 1876 | Spill(current); |
| 1877 | return; |
| 1878 | } |
| 1879 | |
| 1880 | |
| 1881 | LifetimePosition use_pos[DoubleRegister::kMaxNumAllocatableRegisters]; |
| 1882 | LifetimePosition block_pos[DoubleRegister::kMaxNumAllocatableRegisters]; |
| 1883 | |
| 1884 | for (int i = 0; i < num_registers_; i++) { |
| 1885 | use_pos[i] = block_pos[i] = LifetimePosition::MaxPosition(); |
| 1886 | } |
| 1887 | |
| 1888 | for (int i = 0; i < active_live_ranges_.length(); ++i) { |
| 1889 | LiveRange* range = active_live_ranges_[i]; |
| 1890 | int cur_reg = range->assigned_register(); |
| 1891 | if (range->IsFixed() || !range->CanBeSpilled(current->Start())) { |
| 1892 | block_pos[cur_reg] = use_pos[cur_reg] = |
| 1893 | LifetimePosition::FromInstructionIndex(0); |
| 1894 | } else { |
| 1895 | UsePosition* next_use = |
| 1896 | range->NextUsePositionRegisterIsBeneficial(current->Start()); |
| 1897 | if (next_use == NULL) { |
| 1898 | use_pos[cur_reg] = range->End(); |
| 1899 | } else { |
| 1900 | use_pos[cur_reg] = next_use->pos(); |
| 1901 | } |
| 1902 | } |
| 1903 | } |
| 1904 | |
| 1905 | for (int i = 0; i < inactive_live_ranges_.length(); ++i) { |
| 1906 | LiveRange* range = inactive_live_ranges_.at(i); |
| 1907 | DCHECK(range->End().Value() > current->Start().Value()); |
| 1908 | LifetimePosition next_intersection = range->FirstIntersection(current); |
| 1909 | if (!next_intersection.IsValid()) continue; |
| 1910 | int cur_reg = range->assigned_register(); |
| 1911 | if (range->IsFixed()) { |
| 1912 | block_pos[cur_reg] = Min(block_pos[cur_reg], next_intersection); |
| 1913 | use_pos[cur_reg] = Min(block_pos[cur_reg], use_pos[cur_reg]); |
| 1914 | } else { |
| 1915 | use_pos[cur_reg] = Min(use_pos[cur_reg], next_intersection); |
| 1916 | } |
| 1917 | } |
| 1918 | |
| 1919 | int reg = 0; |
| 1920 | for (int i = 1; i < RegisterCount(); ++i) { |
| 1921 | if (use_pos[i].Value() > use_pos[reg].Value()) { |
| 1922 | reg = i; |
| 1923 | } |
| 1924 | } |
| 1925 | |
| 1926 | LifetimePosition pos = use_pos[reg]; |
| 1927 | |
| 1928 | if (pos.Value() < register_use->pos().Value()) { |
| 1929 | // All registers are blocked before the first use that requires a register. |
| 1930 | // Spill starting part of live range up to that use. |
| 1931 | SpillBetween(current, current->Start(), register_use->pos()); |
| 1932 | return; |
| 1933 | } |
| 1934 | |
| 1935 | if (block_pos[reg].Value() < current->End().Value()) { |
| 1936 | // Register becomes blocked before the current range end. Split before that |
| 1937 | // position. |
| 1938 | LiveRange* tail = SplitBetween(current, current->Start(), |
| 1939 | block_pos[reg].InstructionStart()); |
| 1940 | if (!AllocationOk()) return; |
| 1941 | AddToUnhandledSorted(tail); |
| 1942 | } |
| 1943 | |
| 1944 | // Register reg is not blocked for the whole range. |
| 1945 | DCHECK(block_pos[reg].Value() >= current->End().Value()); |
| 1946 | TraceAlloc("Assigning blocked reg %s to live range %d\n", RegisterName(reg), |
| 1947 | current->id()); |
| 1948 | SetLiveRangeAssignedRegister(current, reg); |
| 1949 | |
| 1950 | // This register was not free. Thus we need to find and spill |
| 1951 | // parts of active and inactive live regions that use the same register |
| 1952 | // at the same lifetime positions as current. |
| 1953 | SplitAndSpillIntersecting(current); |
| 1954 | } |
| 1955 | |
| 1956 | |
| 1957 | LifetimePosition RegisterAllocator::FindOptimalSpillingPos( |
| 1958 | LiveRange* range, LifetimePosition pos) { |
| 1959 | BasicBlock* block = GetBlock(pos.InstructionStart()); |
| 1960 | BasicBlock* loop_header = |
| 1961 | block->IsLoopHeader() ? block : code()->GetContainingLoop(block); |
| 1962 | |
| 1963 | if (loop_header == NULL) return pos; |
| 1964 | |
| 1965 | UsePosition* prev_use = range->PreviousUsePositionRegisterIsBeneficial(pos); |
| 1966 | |
| 1967 | while (loop_header != NULL) { |
| 1968 | // We are going to spill live range inside the loop. |
| 1969 | // If possible try to move spilling position backwards to loop header. |
| 1970 | // This will reduce number of memory moves on the back edge. |
| 1971 | LifetimePosition loop_start = LifetimePosition::FromInstructionIndex( |
| 1972 | loop_header->first_instruction_index()); |
| 1973 | |
| 1974 | if (range->Covers(loop_start)) { |
| 1975 | if (prev_use == NULL || prev_use->pos().Value() < loop_start.Value()) { |
| 1976 | // No register beneficial use inside the loop before the pos. |
| 1977 | pos = loop_start; |
| 1978 | } |
| 1979 | } |
| 1980 | |
| 1981 | // Try hoisting out to an outer loop. |
| 1982 | loop_header = code()->GetContainingLoop(loop_header); |
| 1983 | } |
| 1984 | |
| 1985 | return pos; |
| 1986 | } |
| 1987 | |
| 1988 | |
| 1989 | void RegisterAllocator::SplitAndSpillIntersecting(LiveRange* current) { |
| 1990 | DCHECK(current->HasRegisterAssigned()); |
| 1991 | int reg = current->assigned_register(); |
| 1992 | LifetimePosition split_pos = current->Start(); |
| 1993 | for (int i = 0; i < active_live_ranges_.length(); ++i) { |
| 1994 | LiveRange* range = active_live_ranges_[i]; |
| 1995 | if (range->assigned_register() == reg) { |
| 1996 | UsePosition* next_pos = range->NextRegisterPosition(current->Start()); |
| 1997 | LifetimePosition spill_pos = FindOptimalSpillingPos(range, split_pos); |
| 1998 | if (next_pos == NULL) { |
| 1999 | SpillAfter(range, spill_pos); |
| 2000 | } else { |
| 2001 | // When spilling between spill_pos and next_pos ensure that the range |
| 2002 | // remains spilled at least until the start of the current live range. |
| 2003 | // This guarantees that we will not introduce new unhandled ranges that |
| 2004 | // start before the current range as this violates allocation invariant |
| 2005 | // and will lead to an inconsistent state of active and inactive |
| 2006 | // live-ranges: ranges are allocated in order of their start positions, |
| 2007 | // ranges are retired from active/inactive when the start of the |
| 2008 | // current live-range is larger than their end. |
| 2009 | SpillBetweenUntil(range, spill_pos, current->Start(), next_pos->pos()); |
| 2010 | } |
| 2011 | if (!AllocationOk()) return; |
| 2012 | ActiveToHandled(range); |
| 2013 | --i; |
| 2014 | } |
| 2015 | } |
| 2016 | |
| 2017 | for (int i = 0; i < inactive_live_ranges_.length(); ++i) { |
| 2018 | LiveRange* range = inactive_live_ranges_[i]; |
| 2019 | DCHECK(range->End().Value() > current->Start().Value()); |
| 2020 | if (range->assigned_register() == reg && !range->IsFixed()) { |
| 2021 | LifetimePosition next_intersection = range->FirstIntersection(current); |
| 2022 | if (next_intersection.IsValid()) { |
| 2023 | UsePosition* next_pos = range->NextRegisterPosition(current->Start()); |
| 2024 | if (next_pos == NULL) { |
| 2025 | SpillAfter(range, split_pos); |
| 2026 | } else { |
| 2027 | next_intersection = Min(next_intersection, next_pos->pos()); |
| 2028 | SpillBetween(range, split_pos, next_intersection); |
| 2029 | } |
| 2030 | if (!AllocationOk()) return; |
| 2031 | InactiveToHandled(range); |
| 2032 | --i; |
| 2033 | } |
| 2034 | } |
| 2035 | } |
| 2036 | } |
| 2037 | |
| 2038 | |
| 2039 | bool RegisterAllocator::IsBlockBoundary(LifetimePosition pos) { |
| 2040 | return pos.IsInstructionStart() && |
| 2041 | InstructionAt(pos.InstructionIndex())->IsBlockStart(); |
| 2042 | } |
| 2043 | |
| 2044 | |
| 2045 | LiveRange* RegisterAllocator::SplitRangeAt(LiveRange* range, |
| 2046 | LifetimePosition pos) { |
| 2047 | DCHECK(!range->IsFixed()); |
| 2048 | TraceAlloc("Splitting live range %d at %d\n", range->id(), pos.Value()); |
| 2049 | |
| 2050 | if (pos.Value() <= range->Start().Value()) return range; |
| 2051 | |
| 2052 | // We can't properly connect liveranges if split occured at the end |
| 2053 | // of control instruction. |
| 2054 | DCHECK(pos.IsInstructionStart() || |
| 2055 | !InstructionAt(pos.InstructionIndex())->IsControl()); |
| 2056 | |
| 2057 | int vreg = GetVirtualRegister(); |
| 2058 | if (!AllocationOk()) return NULL; |
| 2059 | LiveRange* result = LiveRangeFor(vreg); |
| 2060 | range->SplitAt(pos, result, zone()); |
| 2061 | return result; |
| 2062 | } |
| 2063 | |
| 2064 | |
| 2065 | LiveRange* RegisterAllocator::SplitBetween(LiveRange* range, |
| 2066 | LifetimePosition start, |
| 2067 | LifetimePosition end) { |
| 2068 | DCHECK(!range->IsFixed()); |
| 2069 | TraceAlloc("Splitting live range %d in position between [%d, %d]\n", |
| 2070 | range->id(), start.Value(), end.Value()); |
| 2071 | |
| 2072 | LifetimePosition split_pos = FindOptimalSplitPos(start, end); |
| 2073 | DCHECK(split_pos.Value() >= start.Value()); |
| 2074 | return SplitRangeAt(range, split_pos); |
| 2075 | } |
| 2076 | |
| 2077 | |
| 2078 | LifetimePosition RegisterAllocator::FindOptimalSplitPos(LifetimePosition start, |
| 2079 | LifetimePosition end) { |
| 2080 | int start_instr = start.InstructionIndex(); |
| 2081 | int end_instr = end.InstructionIndex(); |
| 2082 | DCHECK(start_instr <= end_instr); |
| 2083 | |
| 2084 | // We have no choice |
| 2085 | if (start_instr == end_instr) return end; |
| 2086 | |
| 2087 | BasicBlock* start_block = GetBlock(start); |
| 2088 | BasicBlock* end_block = GetBlock(end); |
| 2089 | |
| 2090 | if (end_block == start_block) { |
| 2091 | // The interval is split in the same basic block. Split at the latest |
| 2092 | // possible position. |
| 2093 | return end; |
| 2094 | } |
| 2095 | |
| 2096 | BasicBlock* block = end_block; |
| 2097 | // Find header of outermost loop. |
| 2098 | // TODO(titzer): fix redundancy below. |
| 2099 | while (code()->GetContainingLoop(block) != NULL && |
| 2100 | code()->GetContainingLoop(block)->rpo_number_ > |
| 2101 | start_block->rpo_number_) { |
| 2102 | block = code()->GetContainingLoop(block); |
| 2103 | } |
| 2104 | |
| 2105 | // We did not find any suitable outer loop. Split at the latest possible |
| 2106 | // position unless end_block is a loop header itself. |
| 2107 | if (block == end_block && !end_block->IsLoopHeader()) return end; |
| 2108 | |
| 2109 | return LifetimePosition::FromInstructionIndex( |
| 2110 | block->first_instruction_index()); |
| 2111 | } |
| 2112 | |
| 2113 | |
| 2114 | void RegisterAllocator::SpillAfter(LiveRange* range, LifetimePosition pos) { |
| 2115 | LiveRange* second_part = SplitRangeAt(range, pos); |
| 2116 | if (!AllocationOk()) return; |
| 2117 | Spill(second_part); |
| 2118 | } |
| 2119 | |
| 2120 | |
| 2121 | void RegisterAllocator::SpillBetween(LiveRange* range, LifetimePosition start, |
| 2122 | LifetimePosition end) { |
| 2123 | SpillBetweenUntil(range, start, start, end); |
| 2124 | } |
| 2125 | |
| 2126 | |
| 2127 | void RegisterAllocator::SpillBetweenUntil(LiveRange* range, |
| 2128 | LifetimePosition start, |
| 2129 | LifetimePosition until, |
| 2130 | LifetimePosition end) { |
| 2131 | CHECK(start.Value() < end.Value()); |
| 2132 | LiveRange* second_part = SplitRangeAt(range, start); |
| 2133 | if (!AllocationOk()) return; |
| 2134 | |
| 2135 | if (second_part->Start().Value() < end.Value()) { |
| 2136 | // The split result intersects with [start, end[. |
| 2137 | // Split it at position between ]start+1, end[, spill the middle part |
| 2138 | // and put the rest to unhandled. |
| 2139 | LiveRange* third_part = SplitBetween( |
| 2140 | second_part, Max(second_part->Start().InstructionEnd(), until), |
| 2141 | end.PrevInstruction().InstructionEnd()); |
| 2142 | if (!AllocationOk()) return; |
| 2143 | |
| 2144 | DCHECK(third_part != second_part); |
| 2145 | |
| 2146 | Spill(second_part); |
| 2147 | AddToUnhandledSorted(third_part); |
| 2148 | } else { |
| 2149 | // The split result does not intersect with [start, end[. |
| 2150 | // Nothing to spill. Just put it to unhandled as whole. |
| 2151 | AddToUnhandledSorted(second_part); |
| 2152 | } |
| 2153 | } |
| 2154 | |
| 2155 | |
| 2156 | void RegisterAllocator::Spill(LiveRange* range) { |
| 2157 | DCHECK(!range->IsSpilled()); |
| 2158 | TraceAlloc("Spilling live range %d\n", range->id()); |
| 2159 | LiveRange* first = range->TopLevel(); |
| 2160 | |
| 2161 | if (!first->HasAllocatedSpillOperand()) { |
| 2162 | InstructionOperand* op = TryReuseSpillSlot(range); |
| 2163 | if (op == NULL) { |
| 2164 | // Allocate a new operand referring to the spill slot. |
| 2165 | RegisterKind kind = range->Kind(); |
| 2166 | int index = code()->frame()->AllocateSpillSlot(kind == DOUBLE_REGISTERS); |
| 2167 | if (kind == DOUBLE_REGISTERS) { |
| 2168 | op = DoubleStackSlotOperand::Create(index, zone()); |
| 2169 | } else { |
| 2170 | DCHECK(kind == GENERAL_REGISTERS); |
| 2171 | op = StackSlotOperand::Create(index, zone()); |
| 2172 | } |
| 2173 | } |
| 2174 | first->SetSpillOperand(op); |
| 2175 | } |
| 2176 | range->MakeSpilled(code_zone()); |
| 2177 | } |
| 2178 | |
| 2179 | |
| 2180 | int RegisterAllocator::RegisterCount() const { return num_registers_; } |
| 2181 | |
| 2182 | |
| 2183 | #ifdef DEBUG |
| 2184 | |
| 2185 | |
| 2186 | void RegisterAllocator::Verify() const { |
| 2187 | for (int i = 0; i < live_ranges()->length(); ++i) { |
| 2188 | LiveRange* current = live_ranges()->at(i); |
| 2189 | if (current != NULL) current->Verify(); |
| 2190 | } |
| 2191 | } |
| 2192 | |
| 2193 | |
| 2194 | #endif |
| 2195 | |
| 2196 | |
| 2197 | void RegisterAllocator::SetLiveRangeAssignedRegister(LiveRange* range, |
| 2198 | int reg) { |
| 2199 | if (range->Kind() == DOUBLE_REGISTERS) { |
| 2200 | assigned_double_registers_->Add(reg); |
| 2201 | } else { |
| 2202 | DCHECK(range->Kind() == GENERAL_REGISTERS); |
| 2203 | assigned_registers_->Add(reg); |
| 2204 | } |
| 2205 | range->set_assigned_register(reg, code_zone()); |
| 2206 | } |
| 2207 | |
| 2208 | |
| 2209 | RegisterAllocatorPhase::RegisterAllocatorPhase(const char* name, |
| 2210 | RegisterAllocator* allocator) |
| 2211 | : CompilationPhase(name, allocator->code()->linkage()->info()), |
| 2212 | allocator_(allocator) { |
| 2213 | if (FLAG_turbo_stats) { |
| 2214 | allocator_zone_start_allocation_size_ = |
| 2215 | allocator->zone()->allocation_size(); |
| 2216 | } |
| 2217 | } |
| 2218 | |
| 2219 | |
| 2220 | RegisterAllocatorPhase::~RegisterAllocatorPhase() { |
| 2221 | if (FLAG_turbo_stats) { |
| 2222 | unsigned size = allocator_->zone()->allocation_size() - |
| 2223 | allocator_zone_start_allocation_size_; |
| 2224 | isolate()->GetTStatistics()->SaveTiming(name(), base::TimeDelta(), size); |
| 2225 | } |
| 2226 | #ifdef DEBUG |
| 2227 | if (allocator_ != NULL) allocator_->Verify(); |
| 2228 | #endif |
| 2229 | } |
| 2230 | } |
| 2231 | } |
| 2232 | } // namespace v8::internal::compiler |