debug-coverage.cc 24 KB
Newer Older
1 2 3 4 5 6
// Copyright 2017 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/debug/debug-coverage.h"

7
#include "src/ast/ast-source-ranges.h"
8
#include "src/ast/ast.h"
9
#include "src/base/hashmap.h"
10
#include "src/debug/debug.h"
11
#include "src/deoptimizer/deoptimizer.h"
12 13
#include "src/execution/frames-inl.h"
#include "src/execution/isolate.h"
14
#include "src/objects/debug-objects-inl.h"
15
#include "src/objects/objects.h"
16 17 18 19 20

namespace v8 {
namespace internal {

class SharedToCounterMap
21
    : public base::TemplateHashMapImpl<SharedFunctionInfo, uint32_t,
22
                                       base::KeyEqualityMatcher<Object>,
23 24
                                       base::DefaultAllocationPolicy> {
 public:
25
  using Entry = base::TemplateHashMapEntry<SharedFunctionInfo, uint32_t>;
26
  inline void Add(SharedFunctionInfo key, uint32_t count) {
27 28 29 30 31 32 33 34 35
    Entry* entry = LookupOrInsert(key, Hash(key), []() { return 0; });
    uint32_t old_count = entry->value;
    if (UINT32_MAX - count < old_count) {
      entry->value = UINT32_MAX;
    } else {
      entry->value = old_count + count;
    }
  }

36
  inline uint32_t Get(SharedFunctionInfo key) {
37 38 39 40 41 42
    Entry* entry = Lookup(key, Hash(key));
    if (entry == nullptr) return 0;
    return entry->value;
  }

 private:
43 44
  static uint32_t Hash(SharedFunctionInfo key) {
    return static_cast<uint32_t>(key.ptr());
45 46
  }

47
  DisallowHeapAllocation no_gc;
48 49
};

50
namespace {
51
int StartPosition(SharedFunctionInfo info) {
52 53
  int start = info.function_token_position();
  if (start == kNoSourcePosition) start = info.StartPosition();
54 55 56
  return start;
}

57
bool CompareSharedFunctionInfo(SharedFunctionInfo a, SharedFunctionInfo b) {
58 59
  int a_start = StartPosition(a);
  int b_start = StartPosition(b);
60
  if (a_start == b_start) return a.EndPosition() > b.EndPosition();
61 62
  return a_start < b_start;
}
63 64

bool CompareCoverageBlock(const CoverageBlock& a, const CoverageBlock& b) {
65 66
  DCHECK_NE(kNoSourcePosition, a.start);
  DCHECK_NE(kNoSourcePosition, b.start);
67 68 69 70
  if (a.start == b.start) return a.end > b.end;
  return a.start < b.start;
}

71 72 73 74 75
void SortBlockData(std::vector<CoverageBlock>& v) {
  // Sort according to the block nesting structure.
  std::sort(v.begin(), v.end(), CompareCoverageBlock);
}

76
std::vector<CoverageBlock> GetSortedBlockData(SharedFunctionInfo shared) {
77
  DCHECK(shared.HasCoverageInfo());
78

79
  CoverageInfo coverage_info =
80
      CoverageInfo::cast(shared.GetDebugInfo().coverage_info());
81

82
  std::vector<CoverageBlock> result;
83
  if (coverage_info.SlotCount() == 0) return result;
84

85 86 87 88
  for (int i = 0; i < coverage_info.SlotCount(); i++) {
    const int start_pos = coverage_info.StartSourcePosition(i);
    const int until_pos = coverage_info.EndSourcePosition(i);
    const int count = coverage_info.BlockCount(i);
89

90
    DCHECK_NE(kNoSourcePosition, start_pos);
91 92 93
    result.emplace_back(start_pos, until_pos, count);
  }

94
  SortBlockData(result);
95

96 97
  return result;
}
98

99 100 101 102 103 104 105 106
// A utility class to simplify logic for performing passes over block coverage
// ranges. Provides access to the implicit tree structure of ranges (i.e. access
// to parent and sibling blocks), and supports efficient in-place editing and
// deletion. The underlying backing store is the array of CoverageBlocks stored
// on the CoverageFunction.
class CoverageBlockIterator final {
 public:
  explicit CoverageBlockIterator(CoverageFunction* function)
107
      : function_(function) {
108 109 110
    DCHECK(std::is_sorted(function_->blocks.begin(), function_->blocks.end(),
                          CompareCoverageBlock));
  }
111

112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170
  ~CoverageBlockIterator() {
    Finalize();
    DCHECK(std::is_sorted(function_->blocks.begin(), function_->blocks.end(),
                          CompareCoverageBlock));
  }

  bool HasNext() const {
    return read_index_ + 1 < static_cast<int>(function_->blocks.size());
  }

  bool Next() {
    if (!HasNext()) {
      if (!ended_) MaybeWriteCurrent();
      ended_ = true;
      return false;
    }

    // If a block has been deleted, subsequent iteration moves trailing blocks
    // to their updated position within the array.
    MaybeWriteCurrent();

    if (read_index_ == -1) {
      // Initialize the nesting stack with the function range.
      nesting_stack_.emplace_back(function_->start, function_->end,
                                  function_->count);
    } else if (!delete_current_) {
      nesting_stack_.emplace_back(GetBlock());
    }

    delete_current_ = false;
    read_index_++;

    DCHECK(IsActive());

    CoverageBlock& block = GetBlock();
    while (nesting_stack_.size() > 1 &&
           nesting_stack_.back().end <= block.start) {
      nesting_stack_.pop_back();
    }

    DCHECK_IMPLIES(block.start >= function_->end,
                   block.end == kNoSourcePosition);
    DCHECK_NE(block.start, kNoSourcePosition);
    DCHECK_LE(block.end, GetParent().end);

    return true;
  }

  CoverageBlock& GetBlock() {
    DCHECK(IsActive());
    return function_->blocks[read_index_];
  }

  CoverageBlock& GetNextBlock() {
    DCHECK(IsActive());
    DCHECK(HasNext());
    return function_->blocks[read_index_ + 1];
  }

171 172 173 174 175 176
  CoverageBlock& GetPreviousBlock() {
    DCHECK(IsActive());
    DCHECK_GT(read_index_, 0);
    return function_->blocks[read_index_ - 1];
  }

177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192
  CoverageBlock& GetParent() {
    DCHECK(IsActive());
    return nesting_stack_.back();
  }

  bool HasSiblingOrChild() {
    DCHECK(IsActive());
    return HasNext() && GetNextBlock().start < GetParent().end;
  }

  CoverageBlock& GetSiblingOrChild() {
    DCHECK(HasSiblingOrChild());
    DCHECK(IsActive());
    return GetNextBlock();
  }

193 194 195 196
  // A range is considered to be at top level if its parent range is the
  // function range.
  bool IsTopLevel() const { return nesting_stack_.size() == 1; }

197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222
  void DeleteBlock() {
    DCHECK(!delete_current_);
    DCHECK(IsActive());
    delete_current_ = true;
  }

 private:
  void MaybeWriteCurrent() {
    if (delete_current_) return;
    if (read_index_ >= 0 && write_index_ != read_index_) {
      function_->blocks[write_index_] = function_->blocks[read_index_];
    }
    write_index_++;
  }

  void Finalize() {
    while (Next()) {
      // Just iterate to the end.
    }
    function_->blocks.resize(write_index_);
  }

  bool IsActive() const { return read_index_ >= 0 && !ended_; }

  CoverageFunction* function_;
  std::vector<CoverageBlock> nesting_stack_;
223 224 225 226
  bool ended_ = false;
  bool delete_current_ = false;
  int read_index_ = -1;
  int write_index_ = -1;
227 228 229 230
};

bool HaveSameSourceRange(const CoverageBlock& lhs, const CoverageBlock& rhs) {
  return lhs.start == rhs.start && lhs.end == rhs.end;
231
}
232

233 234 235 236 237 238 239 240 241 242 243 244 245 246 247
void MergeDuplicateRanges(CoverageFunction* function) {
  CoverageBlockIterator iter(function);

  while (iter.Next() && iter.HasNext()) {
    CoverageBlock& block = iter.GetBlock();
    CoverageBlock& next_block = iter.GetNextBlock();

    if (!HaveSameSourceRange(block, next_block)) continue;

    DCHECK_NE(kNoSourcePosition, block.end);  // Non-singleton range.
    next_block.count = std::max(block.count, next_block.count);
    iter.DeleteBlock();
  }
}

248 249 250 251 252
// Rewrite position singletons (produced by unconditional control flow
// like return statements, and by continuation counters) into source
// ranges that end at the next sibling range or the end of the parent
// range, whichever comes first.
void RewritePositionSingletonsToRanges(CoverageFunction* function) {
253
  CoverageBlockIterator iter(function);
254

255 256 257
  while (iter.Next()) {
    CoverageBlock& block = iter.GetBlock();
    CoverageBlock& parent = iter.GetParent();
258

259 260
    if (block.start >= function->end) {
      DCHECK_EQ(block.end, kNoSourcePosition);
261 262 263 264
      iter.DeleteBlock();
    } else if (block.end == kNoSourcePosition) {
      // The current block ends at the next sibling block (if it exists) or the
      // end of the parent block otherwise.
265 266 267 268 269 270 271 272 273 274
      if (iter.HasSiblingOrChild()) {
        block.end = iter.GetSiblingOrChild().start;
      } else if (iter.IsTopLevel()) {
        // See https://crbug.com/v8/6661. Functions are special-cased because
        // we never want the closing brace to be uncovered. This is mainly to
        // avoid a noisy UI.
        block.end = parent.end - 1;
      } else {
        block.end = parent.end;
      }
275
    }
276 277
  }
}
278

279
void MergeConsecutiveRanges(CoverageFunction* function) {
280 281 282 283 284
  CoverageBlockIterator iter(function);

  while (iter.Next()) {
    CoverageBlock& block = iter.GetBlock();

285
    if (iter.HasSiblingOrChild()) {
286 287 288 289 290 291 292
      CoverageBlock& sibling = iter.GetSiblingOrChild();
      if (sibling.start == block.end && sibling.count == block.count) {
        // Best-effort: this pass may miss mergeable siblings in the presence of
        // child blocks.
        sibling.start = block.start;
        iter.DeleteBlock();
      }
293
    }
294 295
  }
}
296

297 298 299 300 301 302 303 304 305 306 307 308 309 310 311
void MergeNestedRanges(CoverageFunction* function) {
  CoverageBlockIterator iter(function);

  while (iter.Next()) {
    CoverageBlock& block = iter.GetBlock();
    CoverageBlock& parent = iter.GetParent();

    if (parent.count == block.count) {
      // Transformation may not be valid if sibling blocks exist with a
      // differing count.
      iter.DeleteBlock();
    }
  }
}

312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335
void RewriteFunctionScopeCounter(CoverageFunction* function) {
  // Every function must have at least the top-level function counter.
  DCHECK(!function->blocks.empty());

  CoverageBlockIterator iter(function);
  if (iter.Next()) {
    DCHECK(iter.IsTopLevel());

    CoverageBlock& block = iter.GetBlock();
    if (block.start == SourceRange::kFunctionLiteralSourcePosition &&
        block.end == SourceRange::kFunctionLiteralSourcePosition) {
      // If a function-scope block exists, overwrite the function count. It has
      // a more reliable count than what we get from the FeedbackVector (which
      // is imprecise e.g. for generator functions and optimized code).
      function->count = block.count;

      // Then delete it; for compatibility with non-block coverage modes, the
      // function-scope block is expected in CoverageFunction, not as a
      // CoverageBlock.
      iter.DeleteBlock();
    }
  }
}

336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359
void FilterAliasedSingletons(CoverageFunction* function) {
  CoverageBlockIterator iter(function);

  iter.Next();  // Advance once since we reference the previous block later.

  while (iter.Next()) {
    CoverageBlock& previous_block = iter.GetPreviousBlock();
    CoverageBlock& block = iter.GetBlock();

    bool is_singleton = block.end == kNoSourcePosition;
    bool aliases_start = block.start == previous_block.start;

    if (is_singleton && aliases_start) {
      // The previous block must have a full range since duplicate singletons
      // have already been merged.
      DCHECK_NE(previous_block.end, kNoSourcePosition);
      // Likewise, the next block must have another start position since
      // singletons are sorted to the end.
      DCHECK_IMPLIES(iter.HasNext(), iter.GetNextBlock().start != block.start);
      iter.DeleteBlock();
    }
  }
}

360 361
void FilterUncoveredRanges(CoverageFunction* function) {
  CoverageBlockIterator iter(function);
362

363 364 365 366 367 368
  while (iter.Next()) {
    CoverageBlock& block = iter.GetBlock();
    CoverageBlock& parent = iter.GetParent();
    if (block.count == 0 && parent.count == 0) iter.DeleteBlock();
  }
}
369

370 371
void FilterEmptyRanges(CoverageFunction* function) {
  CoverageBlockIterator iter(function);
372

373 374 375
  while (iter.Next()) {
    CoverageBlock& block = iter.GetBlock();
    if (block.start == block.end) iter.DeleteBlock();
376
  }
377 378
}

379 380 381 382 383 384 385 386 387
void ClampToBinary(CoverageFunction* function) {
  CoverageBlockIterator iter(function);

  while (iter.Next()) {
    CoverageBlock& block = iter.GetBlock();
    if (block.count > 0) block.count = 1;
  }
}

388
void ResetAllBlockCounts(SharedFunctionInfo shared) {
389
  DCHECK(shared.HasCoverageInfo());
390

391
  CoverageInfo coverage_info =
392
      CoverageInfo::cast(shared.GetDebugInfo().coverage_info());
393

394 395
  for (int i = 0; i < coverage_info.SlotCount(); i++) {
    coverage_info.ResetBlockCount(i);
396 397 398
  }
}

399
bool IsBlockMode(debug::CoverageMode mode) {
400
  switch (mode) {
401 402
    case debug::CoverageMode::kBlockBinary:
    case debug::CoverageMode::kBlockCount:
403 404 405 406 407 408
      return true;
    default:
      return false;
  }
}

409
bool IsBinaryMode(debug::CoverageMode mode) {
410
  switch (mode) {
411 412
    case debug::CoverageMode::kBlockBinary:
    case debug::CoverageMode::kPreciseBinary:
413 414 415 416 417 418
      return true;
    default:
      return false;
  }
}

419 420 421
void CollectBlockCoverageInternal(CoverageFunction* function,
                                  SharedFunctionInfo info,
                                  debug::CoverageMode mode) {
422 423
  DCHECK(IsBlockMode(mode));

424 425 426 427
  // Functions with empty source ranges are not interesting to report. This can
  // happen e.g. for internally-generated functions like class constructors.
  if (!function->HasNonEmptySourceRange()) return;

428
  function->has_block_coverage = true;
429
  function->blocks = GetSortedBlockData(info);
430

431
  // If in binary mode, only report counts of 0/1.
432
  if (mode == debug::CoverageMode::kBlockBinary) ClampToBinary(function);
433

434 435 436 437 438 439 440 441 442 443 444
  // To stay compatible with non-block coverage modes, the function-scope count
  // is expected to be in the CoverageFunction, not as part of its blocks.
  // This finds the function-scope counter, overwrites CoverageFunction::count,
  // and removes it from the block list.
  //
  // Important: Must be called before other transformation passes.
  RewriteFunctionScopeCounter(function);

  // Functions without blocks don't need to be processed further.
  if (!function->HasBlocks()) return;

445 446 447 448 449 450 451 452 453
  // Remove singleton ranges with the same start position as a full range and
  // throw away their counts.
  // Singleton ranges are only intended to split existing full ranges and should
  // never expand into a full range. Consider 'if (cond) { ... } else { ... }'
  // as a problematic example; if the then-block produces a continuation
  // singleton, it would incorrectly expand into the else range.
  // For more context, see https://crbug.com/v8/8237.
  FilterAliasedSingletons(function);

454 455 456 457 458
  // Rewrite all singletons (created e.g. by continuations and unconditional
  // control flow) to ranges.
  RewritePositionSingletonsToRanges(function);

  // Merge nested and consecutive ranges with identical counts.
459 460 461 462 463 464 465 466 467
  // Note that it's necessary to merge duplicate ranges prior to merging nested
  // changes in order to avoid invalid transformations. See crbug.com/827530.
  MergeConsecutiveRanges(function);

  SortBlockData(function->blocks);
  MergeDuplicateRanges(function);
  MergeNestedRanges(function);

  MergeConsecutiveRanges(function);
468 469 470 471 472 473 474

  // Filter out ranges with count == 0 unless the immediate parent range has
  // a count != 0.
  FilterUncoveredRanges(function);

  // Filter out ranges of zero length.
  FilterEmptyRanges(function);
475 476 477 478 479
}

void CollectBlockCoverage(CoverageFunction* function, SharedFunctionInfo info,
                          debug::CoverageMode mode) {
  CollectBlockCoverageInternal(function, info, mode);
480

481 482
  // Reset all counters on the DebugInfo to zero.
  ResetAllBlockCounts(info);
483
}
484 485
}  // anonymous namespace

486
std::unique_ptr<Coverage> Coverage::CollectPrecise(Isolate* isolate) {
487
  DCHECK(!isolate->is_best_effort_code_coverage());
488 489
  std::unique_ptr<Coverage> result =
      Collect(isolate, isolate->code_coverage_mode());
490 491 492
  if (!isolate->is_collecting_type_profile() &&
      (isolate->is_precise_binary_code_coverage() ||
       isolate->is_block_binary_code_coverage())) {
493 494
    // We do not have to hold onto feedback vectors for invocations we already
    // reported. So we can reset the list.
495
    isolate->SetFeedbackVectorsForProfilingTools(*ArrayList::New(isolate, 0));
496 497 498 499
  }
  return result;
}

500
std::unique_ptr<Coverage> Coverage::CollectBestEffort(Isolate* isolate) {
501
  return Collect(isolate, v8::debug::CoverageMode::kBestEffort);
502 503
}

504
std::unique_ptr<Coverage> Coverage::Collect(
505
    Isolate* isolate, v8::debug::CoverageMode collectionMode) {
506
  SharedToCounterMap counter_map;
507

508 509
  const bool reset_count =
      collectionMode != v8::debug::CoverageMode::kBestEffort;
510

511
  switch (isolate->code_coverage_mode()) {
512 513 514 515
    case v8::debug::CoverageMode::kBlockBinary:
    case v8::debug::CoverageMode::kBlockCount:
    case v8::debug::CoverageMode::kPreciseBinary:
    case v8::debug::CoverageMode::kPreciseCount: {
516
      // Feedback vectors are already listed to prevent losing them to GC.
517 518 519 520 521
      DCHECK(isolate->factory()
                 ->feedback_vectors_for_profiling_tools()
                 ->IsArrayList());
      Handle<ArrayList> list = Handle<ArrayList>::cast(
          isolate->factory()->feedback_vectors_for_profiling_tools());
522
      for (int i = 0; i < list->Length(); i++) {
523
        FeedbackVector vector = FeedbackVector::cast(list->Get(i));
524 525 526 527
        SharedFunctionInfo shared = vector.shared_function_info();
        DCHECK(shared.IsSubjectToDebugging());
        uint32_t count = static_cast<uint32_t>(vector.invocation_count());
        if (reset_count) vector.clear_invocation_count();
528 529 530
        counter_map.Add(shared, count);
      }
      break;
531
    }
532
    case v8::debug::CoverageMode::kBestEffort: {
533 534 535
      DCHECK(!isolate->factory()
                  ->feedback_vectors_for_profiling_tools()
                  ->IsArrayList());
536
      DCHECK_EQ(v8::debug::CoverageMode::kBestEffort, collectionMode);
537
      HeapIterator heap_iterator(isolate->heap());
538 539
      for (HeapObject current_obj = heap_iterator.next();
           !current_obj.is_null(); current_obj = heap_iterator.next()) {
540
        if (!current_obj.IsJSFunction()) continue;
541
        JSFunction func = JSFunction::cast(current_obj);
542 543 544 545
        SharedFunctionInfo shared = func.shared();
        if (!shared.IsSubjectToDebugging()) continue;
        if (!(func.has_feedback_vector() ||
              func.has_closure_feedback_cell_array()))
546 547
          continue;
        uint32_t count = 0;
548 549 550 551
        if (func.has_feedback_vector()) {
          count =
              static_cast<uint32_t>(func.feedback_vector().invocation_count());
        } else if (func.raw_feedback_cell().interrupt_budget() <
552 553 554 555 556
                   FLAG_budget_for_feedback_vector_allocation) {
          // We haven't allocated feedback vector, but executed the function
          // atleast once. We don't have precise invocation count here.
          count = 1;
        }
557 558
        counter_map.Add(shared, count);
      }
559 560 561 562 563 564

      // Also check functions on the stack to collect the count map. With lazy
      // feedback allocation we may miss counting functions if the feedback
      // vector wasn't allocated yet and the function's interrupt budget wasn't
      // updated (i.e. it didn't execute return / jump).
      for (JavaScriptFrameIterator it(isolate); !it.done(); it.Advance()) {
565
        SharedFunctionInfo shared = it.frame()->function().shared();
566 567 568
        if (counter_map.Get(shared) != 0) continue;
        counter_map.Add(shared, 1);
      }
569
      break;
570
    }
571 572 573 574
  }

  // Iterate shared function infos of every script and build a mapping
  // between source ranges and invocation counts.
575
  std::unique_ptr<Coverage> result(new Coverage());
576
  Script::Iterator scripts(isolate);
577 578
  for (Script script = scripts.Next(); !script.is_null();
       script = scripts.Next()) {
579
    if (!script.IsUserJavaScript()) continue;
580 581

    // Create and add new script data.
582
    Handle<Script> script_handle(script, isolate);
583
    result->emplace_back(script_handle);
584
    std::vector<CoverageFunction>* functions = &result->back().functions;
585

586
    std::vector<SharedFunctionInfo> sorted;
587 588

    {
589
      // Sort functions by start position, from outer to inner functions.
590
      SharedFunctionInfo::ScriptIterator infos(isolate, *script_handle);
591 592
      for (SharedFunctionInfo info = infos.Next(); !info.is_null();
           info = infos.Next()) {
593 594
        sorted.push_back(info);
      }
595 596 597
      std::sort(sorted.begin(), sorted.end(), CompareSharedFunctionInfo);
    }

598 599 600
    // Stack to track nested functions, referring function by index.
    std::vector<size_t> nesting;

601
    // Use sorted list to reconstruct function nesting.
602
    for (SharedFunctionInfo info : sorted) {
603
      int start = StartPosition(info);
604
      int end = info.EndPosition();
605
      uint32_t count = counter_map.Get(info);
606 607 608 609
      // Find the correct outer function based on start position.
      while (!nesting.empty() && functions->at(nesting.back()).end <= start) {
        nesting.pop_back();
      }
610 611
      if (count != 0) {
        switch (collectionMode) {
612 613
          case v8::debug::CoverageMode::kBlockCount:
          case v8::debug::CoverageMode::kPreciseCount:
614
            break;
615 616
          case v8::debug::CoverageMode::kBlockBinary:
          case v8::debug::CoverageMode::kPreciseBinary:
617 618
            count = info.has_reported_binary_coverage() ? 0 : 1;
            info.set_has_reported_binary_coverage(true);
619
            break;
620
          case v8::debug::CoverageMode::kBestEffort:
621 622 623 624
            count = 1;
            break;
        }
      }
625

626
      Handle<String> name(info.DebugName(), isolate);
627 628
      CoverageFunction function(start, end, count, name);

629
      if (IsBlockMode(collectionMode) && info.HasCoverageInfo()) {
630
        CollectBlockCoverage(&function, info, collectionMode);
631 632 633
      }

      // Only include a function range if itself or its parent function is
634 635 636
      // covered, or if it contains non-trivial block coverage. It must also
      // have a non-empty source range (otherwise it is not interesting to
      // report).
637 638 639 640
      bool is_covered = (count != 0);
      bool parent_is_covered =
          (!nesting.empty() && functions->at(nesting.back()).count != 0);
      bool has_block_coverage = !function.blocks.empty();
641 642 643 644
      bool function_is_relevant =
          (is_covered || parent_is_covered || has_block_coverage);

      if (function.HasNonEmptySourceRange() && function_is_relevant) {
645 646
        nesting.push_back(functions->size());
        functions->emplace_back(function);
647
      }
648
    }
649 650 651

    // Remove entries for scripts that have no coverage.
    if (functions->empty()) result->pop_back();
652 653 654 655
  }
  return result;
}

656
void Coverage::SelectMode(Isolate* isolate, debug::CoverageMode mode) {
657
  switch (mode) {
658
    case debug::CoverageMode::kBestEffort:
659 660 661 662
      // Note that DevTools switches back to best-effort coverage once the
      // recording is stopped. Since we delete coverage infos at that point, any
      // following coverage recording (without reloads) will be at function
      // granularity.
663
      isolate->debug()->RemoveAllCoverageInfos();
664 665
      if (!isolate->is_collecting_type_profile()) {
        isolate->SetFeedbackVectorsForProfilingTools(
666
            ReadOnlyRoots(isolate).undefined_value());
667
      }
668
      break;
669 670 671 672
    case debug::CoverageMode::kBlockBinary:
    case debug::CoverageMode::kBlockCount:
    case debug::CoverageMode::kPreciseBinary:
    case debug::CoverageMode::kPreciseCount: {
673
      HandleScope scope(isolate);
674

675 676 677
      // Remove all optimized function. Optimized and inlined functions do not
      // increment invocation count.
      Deoptimizer::DeoptimizeAll(isolate);
678

679 680 681 682 683
      std::vector<Handle<JSFunction>> funcs_needing_feedback_vector;
      {
        HeapIterator heap_iterator(isolate->heap());
        for (HeapObject o = heap_iterator.next(); !o.is_null();
             o = heap_iterator.next()) {
684
          if (o.IsJSFunction()) {
685
            JSFunction func = JSFunction::cast(o);
686
            if (func.has_closure_feedback_cell_array()) {
687 688 689
              funcs_needing_feedback_vector.push_back(
                  Handle<JSFunction>(func, isolate));
            }
690
          } else if (IsBinaryMode(mode) && o.IsSharedFunctionInfo()) {
691 692 693 694
            // If collecting binary coverage, reset
            // SFI::has_reported_binary_coverage to avoid optimizing / inlining
            // functions before they have reported coverage.
            SharedFunctionInfo shared = SharedFunctionInfo::cast(o);
695 696
            shared.set_has_reported_binary_coverage(false);
          } else if (o.IsFeedbackVector()) {
697
            // In any case, clear any collected invocation counts.
698
            FeedbackVector::cast(o).clear_invocation_count();
699
          }
700
        }
701
      }
702

703 704 705 706 707 708 709
      for (Handle<JSFunction> func : funcs_needing_feedback_vector) {
        JSFunction::EnsureFeedbackVector(func);
      }

      // Root all feedback vectors to avoid early collection.
      isolate->MaybeInitializeVectorListFromHeap();

710
      break;
711 712
    }
  }
713
  isolate->set_code_coverage_mode(mode);
714 715
}

716 717
}  // namespace internal
}  // namespace v8