1 files changed, 114 insertions, 45 deletions

diff --git a/chromium/v8/src/debug/debug-coverage.cc b/chromium/v8/src/debug/debug-coverage.cc
index 5337f98db93..cb466ab6ab7 100644
--- a/chromium/v8/src/debug/debug-coverage.cc
+++ b/chromium/v8/src/debug/debug-coverage.cc
@@ -54,13 +54,6 @@ int StartPosition(SharedFunctionInfo info) {
   return start;
 }
 
-bool CompareSharedFunctionInfo(SharedFunctionInfo a, SharedFunctionInfo b) {
-  int a_start = StartPosition(a);
-  int b_start = StartPosition(b);
-  if (a_start == b_start) return a.EndPosition() > b.EndPosition();
-  return a_start < b_start;
-}
-
 bool CompareCoverageBlock(const CoverageBlock& a, const CoverageBlock& b) {
   DCHECK_NE(kNoSourcePosition, a.start);
   DCHECK_NE(kNoSourcePosition, b.start);
@@ -482,32 +475,31 @@ void CollectBlockCoverage(CoverageFunction* function, SharedFunctionInfo info,
   // Reset all counters on the DebugInfo to zero.
   ResetAllBlockCounts(info);
 }
-}  // anonymous namespace
 
-std::unique_ptr<Coverage> Coverage::CollectPrecise(Isolate* isolate) {
-  DCHECK(!isolate->is_best_effort_code_coverage());
-  std::unique_ptr<Coverage> result =
-      Collect(isolate, isolate->code_coverage_mode());
-  if (!isolate->is_collecting_type_profile() &&
-      (isolate->is_precise_binary_code_coverage() ||
-       isolate->is_block_binary_code_coverage())) {
-    // We do not have to hold onto feedback vectors for invocations we already
-    // reported. So we can reset the list.
-    isolate->SetFeedbackVectorsForProfilingTools(*ArrayList::New(isolate, 0));
+void PrintBlockCoverage(const CoverageFunction* function,
+                        SharedFunctionInfo info, bool has_nonempty_source_range,
+                        bool function_is_relevant) {
+  DCHECK(FLAG_trace_block_coverage);
+  std::unique_ptr<char[]> function_name =
+      function->name->ToCString(DISALLOW_NULLS, ROBUST_STRING_TRAVERSAL);
+  i::PrintF(
+      "Coverage for function='%s', SFI=%p, has_nonempty_source_range=%d, "
+      "function_is_relevant=%d\n",
+      function_name.get(), reinterpret_cast<void*>(info.ptr()),
+      has_nonempty_source_range, function_is_relevant);
+  i::PrintF("{start: %d, end: %d, count: %d}\n", function->start, function->end,
+            function->count);
+  for (const auto& block : function->blocks) {
+    i::PrintF("{start: %d, end: %d, count: %d}\n", block.start, block.end,
+              block.count);
   }
-  return result;
 }
 
-std::unique_ptr<Coverage> Coverage::CollectBestEffort(Isolate* isolate) {
-  return Collect(isolate, v8::debug::CoverageMode::kBestEffort);
-}
-
-std::unique_ptr<Coverage> Coverage::Collect(
-    Isolate* isolate, v8::debug::CoverageMode collectionMode) {
-  SharedToCounterMap counter_map;
-
+void CollectAndMaybeResetCounts(Isolate* isolate,
+                                SharedToCounterMap* counter_map,
+                                v8::debug::CoverageMode coverage_mode) {
   const bool reset_count =
-      collectionMode != v8::debug::CoverageMode::kBestEffort;
+      coverage_mode != v8::debug::CoverageMode::kBestEffort;
 
   switch (isolate->code_coverage_mode()) {
     case v8::debug::CoverageMode::kBlockBinary:
@@ -526,7 +518,7 @@ std::unique_ptr<Coverage> Coverage::Collect(
         DCHECK(shared.IsSubjectToDebugging());
         uint32_t count = static_cast<uint32_t>(vector.invocation_count());
         if (reset_count) vector.clear_invocation_count();
-        counter_map.Add(shared, count);
+        counter_map->Add(shared, count);
       }
       break;
     }
@@ -534,7 +526,7 @@ std::unique_ptr<Coverage> Coverage::Collect(
       DCHECK(!isolate->factory()
                   ->feedback_vectors_for_profiling_tools()
                   ->IsArrayList());
-      DCHECK_EQ(v8::debug::CoverageMode::kBestEffort, collectionMode);
+      DCHECK_EQ(v8::debug::CoverageMode::kBestEffort, coverage_mode);
       HeapObjectIterator heap_iterator(isolate->heap());
       for (HeapObject current_obj = heap_iterator.Next();
            !current_obj.is_null(); current_obj = heap_iterator.Next()) {
@@ -543,8 +535,9 @@ std::unique_ptr<Coverage> Coverage::Collect(
         SharedFunctionInfo shared = func.shared();
         if (!shared.IsSubjectToDebugging()) continue;
         if (!(func.has_feedback_vector() ||
-              func.has_closure_feedback_cell_array()))
+              func.has_closure_feedback_cell_array())) {
           continue;
+        }
         uint32_t count = 0;
         if (func.has_feedback_vector()) {
           count =
@@ -555,7 +548,7 @@ std::unique_ptr<Coverage> Coverage::Collect(
           // atleast once. We don't have precise invocation count here.
           count = 1;
         }
-        counter_map.Add(shared, count);
+        counter_map->Add(shared, count);
       }
 
       // Also check functions on the stack to collect the count map. With lazy
@@ -564,12 +557,64 @@ std::unique_ptr<Coverage> Coverage::Collect(
       // updated (i.e. it didn't execute return / jump).
       for (JavaScriptFrameIterator it(isolate); !it.done(); it.Advance()) {
         SharedFunctionInfo shared = it.frame()->function().shared();
-        if (counter_map.Get(shared) != 0) continue;
-        counter_map.Add(shared, 1);
+        if (counter_map->Get(shared) != 0) continue;
+        counter_map->Add(shared, 1);
       }
       break;
     }
   }
+}
+
+// A {SFI, count} tuple is used to sort by source range (stored on
+// the SFI) and call count (in the counter map).
+struct SharedFunctionInfoAndCount {
+  SharedFunctionInfoAndCount(SharedFunctionInfo info, uint32_t count)
+      : info(info),
+        count(count),
+        start(StartPosition(info)),
+        end(info.EndPosition()) {}
+
+  // Sort by:
+  // - start, ascending.
+  // - end, descending.
+  // - count, ascending.
+  bool operator<(const SharedFunctionInfoAndCount& that) const {
+    if (this->start != that.start) return this->start < that.start;
+    if (this->end != that.end) return this->end > that.end;
+    return this->count < that.count;
+  }
+
+  SharedFunctionInfo info;
+  uint32_t count;
+  int start;
+  int end;
+};
+
+}  // anonymous namespace
+
+std::unique_ptr<Coverage> Coverage::CollectPrecise(Isolate* isolate) {
+  DCHECK(!isolate->is_best_effort_code_coverage());
+  std::unique_ptr<Coverage> result =
+      Collect(isolate, isolate->code_coverage_mode());
+  if (!isolate->is_collecting_type_profile() &&
+      (isolate->is_precise_binary_code_coverage() ||
+       isolate->is_block_binary_code_coverage())) {
+    // We do not have to hold onto feedback vectors for invocations we already
+    // reported. So we can reset the list.
+    isolate->SetFeedbackVectorsForProfilingTools(*ArrayList::New(isolate, 0));
+  }
+  return result;
+}
+
+std::unique_ptr<Coverage> Coverage::CollectBestEffort(Isolate* isolate) {
+  return Collect(isolate, v8::debug::CoverageMode::kBestEffort);
+}
+
+std::unique_ptr<Coverage> Coverage::Collect(
+    Isolate* isolate, v8::debug::CoverageMode collectionMode) {
+  // Collect call counts for all functions.
+  SharedToCounterMap counter_map;
+  CollectAndMaybeResetCounts(isolate, &counter_map, collectionMode);
 
   // Iterate shared function infos of every script and build a mapping
   // between source ranges and invocation counts.
@@ -584,30 +629,40 @@ std::unique_ptr<Coverage> Coverage::Collect(
     result->emplace_back(script_handle);
     std::vector<CoverageFunction>* functions = &result->back().functions;
 
-    std::vector<SharedFunctionInfo> sorted;
+    std::vector<SharedFunctionInfoAndCount> sorted;
 
     {
       // Sort functions by start position, from outer to inner functions.
       SharedFunctionInfo::ScriptIterator infos(isolate, *script_handle);
       for (SharedFunctionInfo info = infos.Next(); !info.is_null();
            info = infos.Next()) {
-        sorted.push_back(info);
+        sorted.emplace_back(info, counter_map.Get(info));
       }
-      std::sort(sorted.begin(), sorted.end(), CompareSharedFunctionInfo);
+      std::sort(sorted.begin(), sorted.end());
     }
 
     // Stack to track nested functions, referring function by index.
     std::vector<size_t> nesting;
 
     // Use sorted list to reconstruct function nesting.
-    for (SharedFunctionInfo info : sorted) {
-      int start = StartPosition(info);
-      int end = info.EndPosition();
-      uint32_t count = counter_map.Get(info);
+    for (const SharedFunctionInfoAndCount& v : sorted) {
+      SharedFunctionInfo info = v.info;
+      int start = v.start;
+      int end = v.end;
+      uint32_t count = v.count;
+
       // Find the correct outer function based on start position.
+      //
+      // This is not robust when considering two functions with identical source
+      // ranges. In this case, it is unclear which function is the inner / outer
+      // function. Above, we ensure that such functions are sorted in ascending
+      // `count` order, so at least our `parent_is_covered` optimization below
+      // should be fine.
+      // TODO(jgruber): Consider removing the optimization.
       while (!nesting.empty() && functions->at(nesting.back()).end <= start) {
         nesting.pop_back();
       }
+
       if (count != 0) {
         switch (collectionMode) {
           case v8::debug::CoverageMode::kBlockCount:
@@ -632,9 +687,7 @@ std::unique_ptr<Coverage> Coverage::Collect(
       }
 
       // Only include a function range if itself or its parent function is
-      // 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).
+      // covered, or if it contains non-trivial block coverage.
       bool is_covered = (count != 0);
       bool parent_is_covered =
           (!nesting.empty() && functions->at(nesting.back()).count != 0);
@@ -642,10 +695,19 @@ std::unique_ptr<Coverage> Coverage::Collect(
       bool function_is_relevant =
           (is_covered || parent_is_covered || has_block_coverage);
 
-      if (function.HasNonEmptySourceRange() && function_is_relevant) {
+      // It must also have a non-empty source range (otherwise it is not
+      // interesting to report).
+      bool has_nonempty_source_range = function.HasNonEmptySourceRange();
+
+      if (has_nonempty_source_range && function_is_relevant) {
         nesting.push_back(functions->size());
         functions->emplace_back(function);
       }
+
+      if (FLAG_trace_block_coverage) {
+        PrintBlockCoverage(&function, info, has_nonempty_source_range,
+                           function_is_relevant);
+      }
     }
 
     // Remove entries for scripts that have no coverage.
@@ -655,6 +717,13 @@ std::unique_ptr<Coverage> Coverage::Collect(
 }
 
 void Coverage::SelectMode(Isolate* isolate, debug::CoverageMode mode) {
+  if (mode != isolate->code_coverage_mode()) {
+    // Changing the coverage mode can change the bytecode that would be
+    // generated for a function, which can interfere with lazy source positions,
+    // so just force source position collection whenever there's such a change.
+    isolate->CollectSourcePositionsForAllBytecodeArrays();
+  }
+
   switch (mode) {
     case debug::CoverageMode::kBestEffort:
       // Note that DevTools switches back to best-effort coverage once the