Revert of [heap] Separate out optimized code map processing. (patchset #3...

Revert of [heap] Separate out optimized code map processing. (patchset #3 id:40001 of https://codereview.chromium.org/1426953006/ )

Reason for revert:
Breaks build: https://uberchromegw.corp.google.com/i/client.v8/builders/V8%20Linux%20-%20nosnap%20-%20debug/builds/3565

Original issue's description:
> [heap] Separate out optimized code map processing.
>
> This separates the post-processing step for optimized code maps out of
> the CodeFlusher. It uses the complete SharedFunctionInfo::Iterator to
> visit all candidates instead of gathering candidates during marking.
>
> Gathering candidates during marking no longer makes sense, now that the
> majority of SharedFunctionInfo objects will hold such an optimized code
> map. Also it reduces complexity of the implementation. Also conflating
> this mechanism with "code flushing" was confusing.
>
> R=ulan@chromium.org
>
> Committed: https://crrev.com/8ad6168d197dd167235c9d342ec7ce37b0daa88b
> Cr-Commit-Position: refs/heads/master@{#31830}

TBR=ulan@chromium.org,yangguo@chromium.org,mvstanton@chromium.org,mstarzinger@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1434503003

Cr-Commit-Position: refs/heads/master@{#31832}

src/heap/gc-tracer.cc

@@ -492,7 +492,6 @@ void GCTracer::PrintNVP() const {
                    "mark_weakrefs=%.1f "
                    "mark_globalhandles=%.1f "
                    "mark_codeflush=%.1f "
-                   "mark_optimizedcodemaps=%.1f "
                    "store_buffer_clear=%.1f "
                    "slots_buffer_clear=%.1f "
                    "sweep=%.2f "
@@ -559,7 +558,6 @@ void GCTracer::PrintNVP() const {
                    current_.scopes[Scope::MC_MARK_WEAK_REFERENCES],
                    current_.scopes[Scope::MC_MARK_GLOBAL_HANDLES],
                    current_.scopes[Scope::MC_MARK_CODE_FLUSH],
-                   current_.scopes[Scope::MC_MARK_OPTIMIZED_CODE_MAPS],
                    current_.scopes[Scope::MC_STORE_BUFFER_CLEAR],
                    current_.scopes[Scope::MC_SLOTS_BUFFER_CLEAR],
                    current_.scopes[Scope::MC_SWEEP],

src/heap/gc-tracer.h

@@ -109,7 +109,6 @@ class GCTracer {
       MC_MARK_WEAK_REFERENCES,
       MC_MARK_GLOBAL_HANDLES,
       MC_MARK_CODE_FLUSH,
-      MC_MARK_OPTIMIZED_CODE_MAPS,
       MC_STORE_BUFFER_CLEAR,
       MC_SLOTS_BUFFER_CLEAR,
       MC_SWEEP,

src/heap/mark-compact-inl.h

@@ -99,6 +99,14 @@ void CodeFlusher::AddCandidate(JSFunction* function) {
 }
 
 
+void CodeFlusher::AddOptimizedCodeMap(SharedFunctionInfo* code_map_holder) {
+  if (GetNextCodeMap(code_map_holder)->IsUndefined()) {
+    SetNextCodeMap(code_map_holder, optimized_code_map_holder_head_);
+    optimized_code_map_holder_head_ = code_map_holder;
+  }
+}
+
+
 JSFunction** CodeFlusher::GetNextCandidateSlot(JSFunction* candidate) {
   return reinterpret_cast<JSFunction**>(
       HeapObject::RawField(candidate, JSFunction::kNextFunctionLinkOffset));
@@ -140,6 +148,26 @@ void CodeFlusher::ClearNextCandidate(SharedFunctionInfo* candidate) {
   candidate->code()->set_gc_metadata(NULL, SKIP_WRITE_BARRIER);
 }
 
+
+SharedFunctionInfo* CodeFlusher::GetNextCodeMap(SharedFunctionInfo* holder) {
+  FixedArray* code_map = FixedArray::cast(holder->optimized_code_map());
+  Object* next_map = code_map->get(SharedFunctionInfo::kNextMapIndex);
+  return reinterpret_cast<SharedFunctionInfo*>(next_map);
+}
+
+
+void CodeFlusher::SetNextCodeMap(SharedFunctionInfo* holder,
+                                 SharedFunctionInfo* next_holder) {
+  FixedArray* code_map = FixedArray::cast(holder->optimized_code_map());
+  code_map->set(SharedFunctionInfo::kNextMapIndex, next_holder);
+}
+
+
+void CodeFlusher::ClearNextCodeMap(SharedFunctionInfo* holder) {
+  FixedArray* code_map = FixedArray::cast(holder->optimized_code_map());
+  code_map->set_undefined(SharedFunctionInfo::kNextMapIndex);
+}
+
 }  // namespace internal
 }  // namespace v8
 

src/heap/mark-compact.cc

@@ -984,6 +984,85 @@ void CodeFlusher::ProcessSharedFunctionInfoCandidates() {
 }
 
 
+void CodeFlusher::ProcessOptimizedCodeMaps() {
+  STATIC_ASSERT(SharedFunctionInfo::kEntryLength == 4);
+
+  SharedFunctionInfo* holder = optimized_code_map_holder_head_;
+  SharedFunctionInfo* next_holder;
+
+  while (holder != NULL) {
+    next_holder = GetNextCodeMap(holder);
+    ClearNextCodeMap(holder);
+
+    // Process context-dependent entries in the optimized code map.
+    FixedArray* code_map = FixedArray::cast(holder->optimized_code_map());
+    int new_length = SharedFunctionInfo::kEntriesStart;
+    int old_length = code_map->length();
+    for (int i = SharedFunctionInfo::kEntriesStart; i < old_length;
+         i += SharedFunctionInfo::kEntryLength) {
+      // Each entry contains [ context, code, literals, ast-id ] as fields.
+      STATIC_ASSERT(SharedFunctionInfo::kEntryLength == 4);
+      Context* context =
+          Context::cast(code_map->get(i + SharedFunctionInfo::kContextOffset));
+      HeapObject* code = HeapObject::cast(
+          code_map->get(i + SharedFunctionInfo::kCachedCodeOffset));
+      FixedArray* literals = FixedArray::cast(
+          code_map->get(i + SharedFunctionInfo::kLiteralsOffset));
+      Smi* ast_id =
+          Smi::cast(code_map->get(i + SharedFunctionInfo::kOsrAstIdOffset));
+      if (Marking::IsWhite(Marking::MarkBitFrom(context))) continue;
+      DCHECK(Marking::IsBlack(Marking::MarkBitFrom(context)));
+      if (Marking::IsWhite(Marking::MarkBitFrom(code))) continue;
+      DCHECK(Marking::IsBlack(Marking::MarkBitFrom(code)));
+      if (Marking::IsWhite(Marking::MarkBitFrom(literals))) continue;
+      DCHECK(Marking::IsBlack(Marking::MarkBitFrom(literals)));
+      // Move every slot in the entry and record slots when needed.
+      code_map->set(new_length + SharedFunctionInfo::kCachedCodeOffset, code);
+      code_map->set(new_length + SharedFunctionInfo::kContextOffset, context);
+      code_map->set(new_length + SharedFunctionInfo::kLiteralsOffset, literals);
+      code_map->set(new_length + SharedFunctionInfo::kOsrAstIdOffset, ast_id);
+      Object** code_slot = code_map->RawFieldOfElementAt(
+          new_length + SharedFunctionInfo::kCachedCodeOffset);
+      isolate_->heap()->mark_compact_collector()->RecordSlot(
+          code_map, code_slot, *code_slot);
+      Object** context_slot = code_map->RawFieldOfElementAt(
+          new_length + SharedFunctionInfo::kContextOffset);
+      isolate_->heap()->mark_compact_collector()->RecordSlot(
+          code_map, context_slot, *context_slot);
+      Object** literals_slot = code_map->RawFieldOfElementAt(
+          new_length + SharedFunctionInfo::kLiteralsOffset);
+      isolate_->heap()->mark_compact_collector()->RecordSlot(
+          code_map, literals_slot, *literals_slot);
+      new_length += SharedFunctionInfo::kEntryLength;
+    }
+
+    // Process context-independent entry in the optimized code map.
+    Object* shared_object = code_map->get(SharedFunctionInfo::kSharedCodeIndex);
+    if (shared_object->IsCode()) {
+      Code* shared_code = Code::cast(shared_object);
+      if (Marking::IsWhite(Marking::MarkBitFrom(shared_code))) {
+        code_map->set_undefined(SharedFunctionInfo::kSharedCodeIndex);
+      } else {
+        DCHECK(Marking::IsBlack(Marking::MarkBitFrom(shared_code)));
+        Object** slot =
+            code_map->RawFieldOfElementAt(SharedFunctionInfo::kSharedCodeIndex);
+        isolate_->heap()->mark_compact_collector()->RecordSlot(code_map, slot,
+                                                               *slot);
+      }
+    }
+
+    // Trim the optimized code map if entries have been removed.
+    if (new_length < old_length) {
+      holder->TrimOptimizedCodeMap(old_length - new_length);
+    }
+
+    holder = next_holder;
+  }
+
+  optimized_code_map_holder_head_ = NULL;
+}
+
+
 void CodeFlusher::EvictCandidate(SharedFunctionInfo* shared_info) {
   // Make sure previous flushing decisions are revisited.
   isolate_->heap()->incremental_marking()->RecordWrites(shared_info);
@@ -1054,6 +1133,44 @@ void CodeFlusher::EvictCandidate(JSFunction* function) {
 }
 
 
+void CodeFlusher::EvictOptimizedCodeMap(SharedFunctionInfo* code_map_holder) {
+  FixedArray* code_map =
+      FixedArray::cast(code_map_holder->optimized_code_map());
+  DCHECK(!code_map->get(SharedFunctionInfo::kNextMapIndex)->IsUndefined());
+
+  // Make sure previous flushing decisions are revisited.
+  isolate_->heap()->incremental_marking()->RecordWrites(code_map);
+  isolate_->heap()->incremental_marking()->RecordWrites(code_map_holder);
+
+  if (FLAG_trace_code_flushing) {
+    PrintF("[code-flushing abandons code-map: ");
+    code_map_holder->ShortPrint();
+    PrintF("]\n");
+  }
+
+  SharedFunctionInfo* holder = optimized_code_map_holder_head_;
+  SharedFunctionInfo* next_holder;
+  if (holder == code_map_holder) {
+    next_holder = GetNextCodeMap(code_map_holder);
+    optimized_code_map_holder_head_ = next_holder;
+    ClearNextCodeMap(code_map_holder);
+  } else {
+    while (holder != NULL) {
+      next_holder = GetNextCodeMap(holder);
+
+      if (next_holder == code_map_holder) {
+        next_holder = GetNextCodeMap(code_map_holder);
+        SetNextCodeMap(holder, next_holder);
+        ClearNextCodeMap(code_map_holder);
+        break;
+      }
+
+      holder = next_holder;
+    }
+  }
+}
+
+
 void CodeFlusher::EvictJSFunctionCandidates() {
   JSFunction* candidate = jsfunction_candidates_head_;
   JSFunction* next_candidate;
@@ -1078,6 +1195,18 @@ void CodeFlusher::EvictSharedFunctionInfoCandidates() {
 }
 
 
+void CodeFlusher::EvictOptimizedCodeMaps() {
+  SharedFunctionInfo* holder = optimized_code_map_holder_head_;
+  SharedFunctionInfo* next_holder;
+  while (holder != NULL) {
+    next_holder = GetNextCodeMap(holder);
+    EvictOptimizedCodeMap(holder);
+    holder = next_holder;
+  }
+  DCHECK(optimized_code_map_holder_head_ == NULL);
+}
+
+
 void CodeFlusher::IteratePointersToFromSpace(ObjectVisitor* v) {
   Heap* heap = isolate_->heap();
 
@@ -2105,13 +2234,6 @@ void MarkCompactCollector::AfterMarking() {
     code_flusher_->ProcessCandidates();
   }
 
-  // Process and clear all optimized code maps.
-  if (!FLAG_flush_optimized_code_cache) {
-    GCTracer::Scope gc_scope(heap()->tracer(),
-                             GCTracer::Scope::MC_MARK_OPTIMIZED_CODE_MAPS);
-    ProcessAndClearOptimizedCodeMaps();
-  }
-
   if (FLAG_track_gc_object_stats) {
     if (FLAG_trace_gc_object_stats) {
       heap()->object_stats_->TraceObjectStats();
@@ -2121,72 +2243,6 @@ void MarkCompactCollector::AfterMarking() {
 }
 
 
-void MarkCompactCollector::ProcessAndClearOptimizedCodeMaps() {
-  SharedFunctionInfo::Iterator iterator(isolate());
-  while (SharedFunctionInfo* shared = iterator.Next()) {
-    if (shared->optimized_code_map()->IsSmi()) continue;
-
-    // Process context-dependent entries in the optimized code map.
-    FixedArray* code_map = FixedArray::cast(shared->optimized_code_map());
-    int new_length = SharedFunctionInfo::kEntriesStart;
-    int old_length = code_map->length();
-    for (int i = SharedFunctionInfo::kEntriesStart; i < old_length;
-         i += SharedFunctionInfo::kEntryLength) {
-      // Each entry contains [ context, code, literals, ast-id ] as fields.
-      STATIC_ASSERT(SharedFunctionInfo::kEntryLength == 4);
-      Context* context =
-          Context::cast(code_map->get(i + SharedFunctionInfo::kContextOffset));
-      HeapObject* code = HeapObject::cast(
-          code_map->get(i + SharedFunctionInfo::kCachedCodeOffset));
-      FixedArray* literals = FixedArray::cast(
-          code_map->get(i + SharedFunctionInfo::kLiteralsOffset));
-      Smi* ast_id =
-          Smi::cast(code_map->get(i + SharedFunctionInfo::kOsrAstIdOffset));
-      if (Marking::IsWhite(Marking::MarkBitFrom(context))) continue;
-      DCHECK(Marking::IsBlack(Marking::MarkBitFrom(context)));
-      if (Marking::IsWhite(Marking::MarkBitFrom(code))) continue;
-      DCHECK(Marking::IsBlack(Marking::MarkBitFrom(code)));
-      if (Marking::IsWhite(Marking::MarkBitFrom(literals))) continue;
-      DCHECK(Marking::IsBlack(Marking::MarkBitFrom(literals)));
-      // Move every slot in the entry and record slots when needed.
-      code_map->set(new_length + SharedFunctionInfo::kCachedCodeOffset, code);
-      code_map->set(new_length + SharedFunctionInfo::kContextOffset, context);
-      code_map->set(new_length + SharedFunctionInfo::kLiteralsOffset, literals);
-      code_map->set(new_length + SharedFunctionInfo::kOsrAstIdOffset, ast_id);
-      Object** code_slot = code_map->RawFieldOfElementAt(
-          new_length + SharedFunctionInfo::kCachedCodeOffset);
-      RecordSlot(code_map, code_slot, *code_slot);
-      Object** context_slot = code_map->RawFieldOfElementAt(
-          new_length + SharedFunctionInfo::kContextOffset);
-      RecordSlot(code_map, context_slot, *context_slot);
-      Object** literals_slot = code_map->RawFieldOfElementAt(
-          new_length + SharedFunctionInfo::kLiteralsOffset);
-      RecordSlot(code_map, literals_slot, *literals_slot);
-      new_length += SharedFunctionInfo::kEntryLength;
-    }
-
-    // Process context-independent entry in the optimized code map.
-    Object* shared_object = code_map->get(SharedFunctionInfo::kSharedCodeIndex);
-    if (shared_object->IsCode()) {
-      Code* shared_code = Code::cast(shared_object);
-      if (Marking::IsWhite(Marking::MarkBitFrom(shared_code))) {
-        code_map->set_undefined(SharedFunctionInfo::kSharedCodeIndex);
-      } else {
-        DCHECK(Marking::IsBlack(Marking::MarkBitFrom(shared_code)));
-        Object** slot =
-            code_map->RawFieldOfElementAt(SharedFunctionInfo::kSharedCodeIndex);
-        RecordSlot(code_map, slot, *slot);
-      }
-    }
-
-    // Trim the optimized code map if entries have been removed.
-    if (new_length < old_length) {
-      shared->TrimOptimizedCodeMap(old_length - new_length);
-    }
-  }
-}
-
-
 void MarkCompactCollector::ClearNonLiveReferences() {
   GCTracer::Scope gc_scope(heap()->tracer(),
                            GCTracer::Scope::MC_NONLIVEREFERENCES);

src/heap/mark-compact.h

@@ -263,9 +263,10 @@ class MarkingDeque {
 // CodeFlusher collects candidates for code flushing during marking and
 // processes those candidates after marking has completed in order to
 // reset those functions referencing code objects that would otherwise
-// be unreachable. Code objects can be referenced in two ways:
+// be unreachable. Code objects can be referenced in three ways:
 //    - SharedFunctionInfo references unoptimized code.
 //    - JSFunction references either unoptimized or optimized code.
+//    - OptimizedCodeMap references optimized code.
 // We are not allowed to flush unoptimized code for functions that got
 // optimized or inlined into optimized code, because we might bailout
 // into the unoptimized code again during deoptimization.
@@ -273,21 +274,26 @@ class CodeFlusher {
  public:
   explicit CodeFlusher(Isolate* isolate)
       : isolate_(isolate),
-        jsfunction_candidates_head_(nullptr),
-        shared_function_info_candidates_head_(nullptr) {}
+        jsfunction_candidates_head_(NULL),
+        shared_function_info_candidates_head_(NULL),
+        optimized_code_map_holder_head_(NULL) {}
 
   inline void AddCandidate(SharedFunctionInfo* shared_info);
   inline void AddCandidate(JSFunction* function);
+  inline void AddOptimizedCodeMap(SharedFunctionInfo* code_map_holder);
 
+  void EvictOptimizedCodeMap(SharedFunctionInfo* code_map_holder);
   void EvictCandidate(SharedFunctionInfo* shared_info);
   void EvictCandidate(JSFunction* function);
 
   void ProcessCandidates() {
+    ProcessOptimizedCodeMaps();
     ProcessSharedFunctionInfoCandidates();
     ProcessJSFunctionCandidates();
   }
 
   void EvictAllCandidates() {
+    EvictOptimizedCodeMaps();
     EvictJSFunctionCandidates();
     EvictSharedFunctionInfoCandidates();
   }
@@ -295,8 +301,10 @@ class CodeFlusher {
   void IteratePointersToFromSpace(ObjectVisitor* v);
 
  private:
+  void ProcessOptimizedCodeMaps();
   void ProcessJSFunctionCandidates();
   void ProcessSharedFunctionInfoCandidates();
+  void EvictOptimizedCodeMaps();
   void EvictJSFunctionCandidates();
   void EvictSharedFunctionInfoCandidates();
 
@@ -313,9 +321,15 @@ class CodeFlusher {
                                       SharedFunctionInfo* next_candidate);
   static inline void ClearNextCandidate(SharedFunctionInfo* candidate);
 
+  static inline SharedFunctionInfo* GetNextCodeMap(SharedFunctionInfo* holder);
+  static inline void SetNextCodeMap(SharedFunctionInfo* holder,
+                                    SharedFunctionInfo* next_holder);
+  static inline void ClearNextCodeMap(SharedFunctionInfo* holder);
+
   Isolate* isolate_;
   JSFunction* jsfunction_candidates_head_;
   SharedFunctionInfo* shared_function_info_candidates_head_;
+  SharedFunctionInfo* optimized_code_map_holder_head_;
 
   DISALLOW_COPY_AND_ASSIGN(CodeFlusher);
 };
@@ -680,14 +694,10 @@ class MarkCompactCollector {
   // collections when incremental marking is aborted.
   void AbortWeakCollections();
 
+
   void ProcessAndClearWeakCells();
   void AbortWeakCells();
 
-  // After all reachable objects have been marked, those entries within
-  // optimized code maps that became unreachable are removed, potentially
-  // trimming or clearing out the entire optimized code map.
-  void ProcessAndClearOptimizedCodeMaps();
-
   // -----------------------------------------------------------------------
   // Phase 2: Sweeping to clear mark bits and free non-live objects for
   // a non-compacting collection.

src/heap/objects-visiting-inl.h

@@ -443,23 +443,23 @@ void StaticMarkingVisitor<StaticVisitor>::VisitSharedFunctionInfo(
   if (FLAG_cleanup_code_caches_at_gc) {
     shared->ClearTypeFeedbackInfoAtGCTime();
   }
-  if (FLAG_flush_optimized_code_cache ||
-      heap->isolate()->serializer_enabled()) {
-    if (!shared->optimized_code_map()->IsSmi()) {
-      // Always flush the optimized code map if requested by flag.
-      shared->ClearOptimizedCodeMap();
-    }
-  } else {
+  if ((FLAG_flush_optimized_code_cache ||
+       heap->isolate()->serializer_enabled()) &&
+      !shared->optimized_code_map()->IsSmi()) {
+    // Always flush the optimized code map if requested by flag.
+    shared->ClearOptimizedCodeMap();
+  }
+  MarkCompactCollector* collector = heap->mark_compact_collector();
+  if (collector->is_code_flushing_enabled()) {
     if (!shared->optimized_code_map()->IsSmi()) {
+      // Add the shared function info holding an optimized code map to
+      // the code flusher for processing of code maps after marking.
+      collector->code_flusher()->AddOptimizedCodeMap(shared);
       // Treat some references within the code map weakly by marking the
-      // code map itself but not pushing it onto the marking deque. The
-      // map will be processed after marking.
+      // code map itself but not pushing it onto the marking deque.
       FixedArray* code_map = FixedArray::cast(shared->optimized_code_map());
       MarkOptimizedCodeMap(heap, code_map);
     }
-  }
-  MarkCompactCollector* collector = heap->mark_compact_collector();
-  if (collector->is_code_flushing_enabled()) {
     if (IsFlushable(heap, shared)) {
       // This function's code looks flushable. But we have to postpone
       // the decision until we see all functions that point to the same
@@ -473,7 +473,6 @@ void StaticMarkingVisitor<StaticVisitor>::VisitSharedFunctionInfo(
       return;
     }
   } else {
-    // TODO(mstarzinger): Drop this case, it shouldn't be done here!
     if (!shared->optimized_code_map()->IsSmi()) {
       // Flush optimized code map on major GCs without code flushing,
       // needed because cached code doesn't contain breakpoints.

src/objects.cc

@@ -11107,6 +11107,16 @@ void SharedFunctionInfo::AddToOptimizedCodeMap(
 
 
 void SharedFunctionInfo::ClearOptimizedCodeMap() {
+  FixedArray* code_map = FixedArray::cast(optimized_code_map());
+
+  // If the next map link slot is already used then the function was
+  // enqueued with code flushing and we remove it now.
+  if (!code_map->get(kNextMapIndex)->IsUndefined()) {
+    CodeFlusher* flusher = GetHeap()->mark_compact_collector()->code_flusher();
+    flusher->EvictOptimizedCodeMap(this);
+  }
+
+  DCHECK(code_map->get(kNextMapIndex)->IsUndefined());
   set_optimized_code_map(Smi::FromInt(0));
 }
 

src/objects.h

@@ -6555,8 +6555,9 @@ class SharedFunctionInfo: public HeapObject {
                         Handle<Object> script_object);
 
   // Layout description of the optimized code map.
-  static const int kSharedCodeIndex = 0;
-  static const int kEntriesStart = 1;
+  static const int kNextMapIndex = 0;
+  static const int kSharedCodeIndex = 1;
+  static const int kEntriesStart = 2;
   static const int kContextOffset = 0;
   static const int kCachedCodeOffset = 1;
   static const int kLiteralsOffset = 2;