deps: V8: cherry-pick 597f885

Original commit message:

    [coverage] Deterministically sort collected shared function infos

    Prior to this CL, collected shared function infos with identical
    source ranges were sorted non-deterministically during coverage
    collection. This lead to non-deterministically incorrectly-reported
    coverage due to an optimization which depended on the sort order later
    on.

    With this CL, we now sort shared function infos by the source range
    *and* call count.

    Bug: v8:6000,v8:9212
    Change-Id: If8bf900727591e71dbd0df621e472a4303f3a353
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1771776
    Reviewed-by: Yang Guo <yangguo@chromium.org>
    Commit-Queue: Jakob Gruber <jgruber@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#63411}

Refs: https://github.com/v8/v8/commit/597f885eaa6189f8c8466ee9916763c679e84e9a

PR-URL: https://github.com/nodejs/node/pull/29367
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

1 files changed, 80 insertions, 44 deletions

diff --git a/deps/v8/src/debug/debug-coverage.cc b/deps/v8/src/debug/debug-coverage.cc
index 5337f98db9..15aad1fcc2 100644
--- a/deps/v8/src/debug/debug-coverage.cc
+++ b/deps/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 +475,12 @@ 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));
-  }
-  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 +499,7 @@ 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 +507,7 @@ 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 +516,9 @@ 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 +529,7 @@ 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 +538,64 @@ 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 +610,40 @@ 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: