Reland of "Store SharedFunctionInfos of a Script in a FixedArray indexed by their ID"

src/objects.cc

 // Copyright 2015 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/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <memory>
 #include <sstream>
@@ skipping 13622 matching lines @@
   isolate->counters()->script_wrappers()->Increment();
   Handle<JSFunction> constructor = isolate->script_function();
   Handle<JSValue> result =
       Handle<JSValue>::cast(isolate->factory()->NewJSObject(constructor));
   result->set_value(*script);
   Handle<WeakCell> cell = isolate->factory()->NewWeakCell(result);
   script->set_wrapper(*cell);
   return result;
 }
 
-
 MaybeHandle<SharedFunctionInfo> Script::FindSharedFunctionInfo(
-    FunctionLiteral* fun) {
-  WeakFixedArray::Iterator iterator(shared_function_infos());
-  SharedFunctionInfo* shared;
-  while ((shared = iterator.Next<SharedFunctionInfo>())) {
-    if (fun->function_token_position() == shared->function_token_position() &&
-        fun->start_position() == shared->start_position() &&
-        fun->end_position() == shared->end_position()) {
-      DCHECK_EQ(fun->function_literal_id(), shared->function_literal_id());
-      return Handle<SharedFunctionInfo>(shared);
-    }
-    DCHECK_NE(fun->function_literal_id(), shared->function_literal_id());
+    Isolate* isolate, FunctionLiteral* fun) {
+  DCHECK_NE(fun->function_literal_id(), FunctionLiteral::kIdTypeInvalid);
+  DCHECK_LT(fun->function_literal_id(), shared_function_infos()->length());
+  Object* shared = shared_function_infos()->get(fun->function_literal_id());
+  if (shared->IsUndefined(isolate) || WeakCell::cast(shared)->cleared()) {
+    return MaybeHandle<SharedFunctionInfo>();
   }
-  return MaybeHandle<SharedFunctionInfo>();
+  return handle(SharedFunctionInfo::cast(WeakCell::cast(shared)->value()));
 }
 
-
 Script::Iterator::Iterator(Isolate* isolate)
     : iterator_(isolate->heap()->script_list()) {}
 
 
 Script* Script::Iterator::Next() { return iterator_.Next<Script>(); }
 
+SharedFunctionInfo::ScriptIterator::ScriptIterator(Handle<Script> script)
+    : ScriptIterator(script->GetIsolate(),
+                     handle(script->shared_function_infos())) {}
 
-SharedFunctionInfo::Iterator::Iterator(Isolate* isolate)
-    : script_iterator_(isolate),
-      sfi_iterator_(isolate->heap()->noscript_shared_function_infos()) {}
+SharedFunctionInfo::ScriptIterator::ScriptIterator(
+    Isolate* isolate, Handle<FixedArray> shared_function_infos)
+    : isolate_(isolate),
+      shared_function_infos_(shared_function_infos),
+      index_(0) {}
 
-
-bool SharedFunctionInfo::Iterator::NextScript() {
-  Script* script = script_iterator_.Next();
-  if (script == NULL) return false;
-  sfi_iterator_.Reset(script->shared_function_infos());
-  return true;
+SharedFunctionInfo* SharedFunctionInfo::ScriptIterator::Next() {
+  while (index_ < shared_function_infos_->length()) {
+    Object* raw = shared_function_infos_->get(index_++);
+    if (raw->IsUndefined(isolate_) || WeakCell::cast(raw)->cleared()) continue;
+    return SharedFunctionInfo::cast(WeakCell::cast(raw)->value());
+  }
+  return nullptr;
 }
 
+void SharedFunctionInfo::ScriptIterator::Reset(Handle<Script> script) {
+  shared_function_infos_ = handle(script->shared_function_infos());
+  index_ = 0;
+}
 
-SharedFunctionInfo* SharedFunctionInfo::Iterator::Next() {
-  do {
-    SharedFunctionInfo* next = sfi_iterator_.Next<SharedFunctionInfo>();
-    if (next != NULL) return next;
-  } while (NextScript());
-  return NULL;
+SharedFunctionInfo::GlobalIterator::GlobalIterator(Isolate* isolate)
+    : script_iterator_(isolate),
+      noscript_sfi_iterator_(isolate->heap()->noscript_shared_function_infos()),
+      sfi_iterator_(handle(script_iterator_.Next(), isolate)) {}
+
+SharedFunctionInfo* SharedFunctionInfo::GlobalIterator::Next() {
+  SharedFunctionInfo* next = noscript_sfi_iterator_.Next<SharedFunctionInfo>();
+  if (next != nullptr) return next;
+  for (;;) {
+    next = sfi_iterator_.Next();
+    if (next != nullptr) return next;
+    Script* next_script = script_iterator_.Next();
+    if (next_script == nullptr) return nullptr;
+    sfi_iterator_.Reset(handle(next_script));
+  }
 }
 
 
 void SharedFunctionInfo::SetScript(Handle<SharedFunctionInfo> shared,
                                    Handle<Object> script_object) {
+  DCHECK_NE(shared->function_literal_id(), FunctionLiteral::kIdTypeInvalid);
   if (shared->script() == *script_object) return;
   Isolate* isolate = shared->GetIsolate();
 
   // Add shared function info to new script's list. If a collection occurs,
   // the shared function info may be temporarily in two lists.
   // This is okay because the gc-time processing of these lists can tolerate
   // duplicates.
-  Handle<Object> list;
   if (script_object->IsScript()) {
     Handle<Script> script = Handle<Script>::cast(script_object);
-    list = handle(script->shared_function_infos(), isolate);
+    Handle<FixedArray> list = handle(script->shared_function_infos(), isolate);
+#ifdef DEBUG
+    DCHECK_LT(shared->function_literal_id(), list->length());
+    if (list->get(shared->function_literal_id())->IsWeakCell() &&
+        !WeakCell::cast(list->get(shared->function_literal_id()))->cleared()) {
+      DCHECK(
+          WeakCell::cast(list->get(shared->function_literal_id()))->value() ==
+          *shared);
+    }
+#endif
+    Handle<WeakCell> cell = isolate->factory()->NewWeakCell(shared);
+    list->set(shared->function_literal_id(), *cell);
   } else {
-    list = isolate->factory()->noscript_shared_function_infos();
-  }
+    Handle<Object> list = isolate->factory()->noscript_shared_function_infos();
 
 #ifdef DEBUG
-  if (FLAG_enable_slow_asserts) {
-    WeakFixedArray::Iterator iterator(*list);
-    SharedFunctionInfo* next;
-    while ((next = iterator.Next<SharedFunctionInfo>())) {
-      DCHECK_NE(next, *shared);
+    if (FLAG_enable_slow_asserts) {
+      WeakFixedArray::Iterator iterator(*list);
+      SharedFunctionInfo* next;
+      while ((next = iterator.Next<SharedFunctionInfo>())) {
+        DCHECK_NE(next, *shared);
+      }
     }
-  }
 #endif  // DEBUG
-  list = WeakFixedArray::Add(list, shared);
 
-  if (script_object->IsScript()) {
-    Handle<Script> script = Handle<Script>::cast(script_object);
-    script->set_shared_function_infos(*list);
-  } else {
+    list = WeakFixedArray::Add(list, shared);
+
     isolate->heap()->SetRootNoScriptSharedFunctionInfos(*list);
   }
 
-  // Remove shared function info from old script's list.
   if (shared->script()->IsScript()) {
+    // Remove shared function info from old script's list.
     Script* old_script = Script::cast(shared->script());
-    if (old_script->shared_function_infos()->IsWeakFixedArray()) {
-      WeakFixedArray* list =
-          WeakFixedArray::cast(old_script->shared_function_infos());
-      list->Remove(shared);
+
+    // Due to liveedit, it might happen that the old_script doesn't know
+    // about the SharedFunctionInfo, so we have to guard against that.
+    Handle<FixedArray> infos(old_script->shared_function_infos(), isolate);
+    if (shared->function_literal_id() < infos->length()) {
+      Object* raw = old_script->shared_function_infos()->get(
+          shared->function_literal_id());
+      if (!raw->IsWeakCell() || WeakCell::cast(raw)->value() == *shared) {
+        old_script->shared_function_infos()->set(
+            shared->function_literal_id(), isolate->heap()->undefined_value());
+      }
     }
   } else {
     // Remove shared function info from root array.
     Object* list = isolate->heap()->noscript_shared_function_infos();
     CHECK(WeakFixedArray::cast(list)->Remove(shared));
   }
 
   // Finally set new script.
   shared->set_script(*script_object);
 }
@@ skipping 244 matching lines @@
   shared_info->set_end_position(lit->end_position());
   shared_info->set_is_declaration(lit->is_declaration());
   shared_info->set_is_named_expression(lit->is_named_expression());
   shared_info->set_is_anonymous_expression(lit->is_anonymous_expression());
   shared_info->set_inferred_name(*lit->inferred_name());
   shared_info->set_allows_lazy_compilation(lit->AllowsLazyCompilation());
   shared_info->set_language_mode(lit->language_mode());
   shared_info->set_uses_arguments(lit->scope()->arguments() != NULL);
   shared_info->set_has_duplicate_parameters(lit->has_duplicate_parameters());
   shared_info->set_is_function(lit->is_function());
-  shared_info->set_never_compiled(true);
   shared_info->set_kind(lit->kind());
   if (!IsConstructable(lit->kind(), lit->language_mode())) {
     shared_info->SetConstructStub(
         *shared_info->GetIsolate()->builtins()->ConstructedNonConstructable());
   }
   shared_info->set_needs_home_object(lit->scope()->NeedsHomeObject());
   shared_info->set_asm_function(lit->scope()->asm_function());
   shared_info->set_requires_class_field_init(lit->requires_class_field_init());
   shared_info->set_is_class_field_initializer(
       lit->is_class_field_initializer());
@@ skipping 6404 matching lines @@
       // depend on this.
       return DICTIONARY_ELEMENTS;
     }
     DCHECK_LE(kind, LAST_ELEMENTS_KIND);
     return kind;
   }
 }
 
 }  // namespace internal
 }  // namespace v8