[vm/isolates] Move saved_initial_field_table to isolate group.

This improves performance of spawn isolate since it drops a need to lock isolate group when spawning new isolate.

Change-Id: I867c13c808a3eb356f3d53323bb8aef06541019e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/147046
Reviewed-by: Ryan Macnak <[email protected]>
Commit-Queue: Alexander Aprelev <[email protected]>

Author: aam

runtime/vm/clustered_snapshot.cc

@@ -1203,10 +1203,6 @@ class FieldDeserializationCluster : public DeserializationCluster {
         field.InitializeGuardedListLengthInObjectOffset();
       }
     }
-
-    Isolate* isolate = Isolate::Current();
-    isolate->set_saved_initial_field_table(
-        std::shared_ptr<FieldTable>(isolate->field_table()->Clone()));
   }
 };
 

runtime/vm/dart.cc

@@ -671,25 +671,10 @@ static bool CloneIntoChildIsolateAOT(Thread* T,
   if (source_isolate_group == nullptr) {
     return false;
   }
-  bool has_found_donor_isolate = false;
-  std::shared_ptr<FieldTable> donor_saved_initial_field_table;
-  source_isolate_group->RunWithLockedGroup([&]() {
-    Isolate* donor_isolate = source_isolate_group->FirstIsolateLocked();
-    if (donor_isolate == nullptr) {
-      return;
-    }
-    has_found_donor_isolate = true;
-    // Initialize field_table with initial values.
-    donor_saved_initial_field_table =
-        donor_isolate->saved_initial_field_table_shareable();
-  });
-  if (!has_found_donor_isolate) {
-    return false;
-  }
   I->isolate_object_store()->Init();
   I->isolate_object_store()->PreallocateObjects();
-  I->set_field_table(T, donor_saved_initial_field_table->Clone());
-  I->set_saved_initial_field_table(donor_saved_initial_field_table);
+  I->set_field_table(
+      T, source_isolate_group->saved_initial_field_table()->Clone());
 
   return true;
 }
@@ -735,6 +720,8 @@ ErrorPtr Dart::InitIsolateFromSnapshot(Thread* T,
     }
 
     ReversePcLookupCache::BuildAndAttachToIsolateGroup(I->group());
+    I->group()->set_saved_initial_field_table(
+        std::shared_ptr<FieldTable>(I->field_table()->Clone()));
 
 #if defined(SUPPORT_TIMELINE)
     if (tbes.enabled()) {

runtime/vm/isolate.cc

@@ -2583,9 +2583,6 @@ void Isolate::VisitObjectPointers(ObjectPointerVisitor* visitor,
 
   // Visit objects in the field table.
   field_table()->VisitObjectPointers(visitor);
-  if (saved_initial_field_table() != nullptr) {
-    saved_initial_field_table()->VisitObjectPointers(visitor);
-  }
 
   visitor->clear_gc_root_type();
   // Visit the objects directly referenced from the isolate structure.
@@ -2756,6 +2753,9 @@ void IsolateGroup::VisitObjectPointers(ObjectPointerVisitor* visitor,
     object_store()->VisitObjectPointers(visitor);
   }
   visitor->VisitPointer(reinterpret_cast<ObjectPtr*>(&saved_unlinked_calls_));
+  if (saved_initial_field_table() != nullptr) {
+    saved_initial_field_table()->VisitObjectPointers(visitor);
+  }
   VisitStackPointers(visitor, validate_frames);
 }
 

runtime/vm/isolate.h

@@ -532,6 +532,16 @@ class IsolateGroup : public IntrusiveDListEntry<IsolateGroup> {
     reverse_pc_lookup_cache_ = table;
   }
 
+  FieldTable* saved_initial_field_table() const {
+    return saved_initial_field_table_.get();
+  }
+  std::shared_ptr<FieldTable> saved_initial_field_table_shareable() {
+    return saved_initial_field_table_;
+  }
+  void set_saved_initial_field_table(std::shared_ptr<FieldTable> field_table) {
+    saved_initial_field_table_ = field_table;
+  }
+
   MutatorThreadPool* thread_pool() { return thread_pool_.get(); }
 
  private:
@@ -618,6 +628,7 @@ class IsolateGroup : public IntrusiveDListEntry<IsolateGroup> {
   std::unique_ptr<DispatchTable> dispatch_table_;
   ReversePcLookupCache* reverse_pc_lookup_cache_ = nullptr;
   ArrayPtr saved_unlinked_calls_;
+  std::shared_ptr<FieldTable> saved_initial_field_table_;
 
   uint32_t isolate_group_flags_ = 0;
 };
@@ -726,16 +737,6 @@ class Isolate : public BaseIsolate, public IntrusiveDListEntry<Isolate> {
     T->field_table_values_ = field_table->table();
   }
 
-  FieldTable* saved_initial_field_table() const {
-    return saved_initial_field_table_.get();
-  }
-  std::shared_ptr<FieldTable> saved_initial_field_table_shareable() {
-    return saved_initial_field_table_;
-  }
-  void set_saved_initial_field_table(std::shared_ptr<FieldTable> field_table) {
-    saved_initial_field_table_ = field_table;
-  }
-
   IsolateObjectStore* isolate_object_store() const {
     return isolate_object_store_.get();
   }
@@ -1372,7 +1373,6 @@ class Isolate : public BaseIsolate, public IntrusiveDListEntry<Isolate> {
 
   IsolateGroup* isolate_group_;
   IdleTimeHandler idle_time_handler_;
-  std::shared_ptr<FieldTable> saved_initial_field_table_;
   std::unique_ptr<IsolateObjectStore> isolate_object_store_;
   // shared in AOT(same pointer as on IsolateGroup), not shared in JIT
   std::shared_ptr<ObjectStore> object_store_shared_ptr_;

runtime/vm/object_store.h

@@ -211,7 +211,6 @@ class ObjectPointerVisitor;
   RW(Array, dispatch_table_code_entries)                                       \
   RW(Array, code_order_table)                                                  \
   RW(Array, obfuscation_map)                                                   \
-  RW(Array, saved_initial_field_values)                                        \
   RW(Class, ffi_pointer_class)                                                 \
   RW(Class, ffi_native_type_class)                                             \
   RW(Class, ffi_struct_class)                                                  \