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

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 11114f9c04d007dc7c4309a23b43230135fbfedd..df1fe6a7c268edd386da9532d8226d451018f43e 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -13645,47 +13645,52 @@ Handle<JSObject> Script::GetWrapper(Handle<Script> script) {
 
 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());
+  if (fun->function_literal_id() == FunctionLiteral::kIdTypeInvalid ||
+      fun->function_literal_id() >= shared_function_infos()->length()) {
+    UNREACHABLE();
+    return MaybeHandle<SharedFunctionInfo>();
   }
-  return MaybeHandle<SharedFunctionInfo>();
+  Object* shared = shared_function_infos()->get(fun->function_literal_id());
+  if (shared->IsSmi() || WeakCell::cast(shared)->cleared()) {
+    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::Iterator::Iterator(Isolate* isolate)
     : script_iterator_(isolate),
-      sfi_iterator_(isolate->heap()->noscript_shared_function_infos()) {}
-
-
-bool SharedFunctionInfo::Iterator::NextScript() {
-  Script* script = script_iterator_.Next();
-  if (script == NULL) return false;
-  sfi_iterator_.Reset(script->shared_function_infos());
-  return true;
+      sfi_iterator_(isolate->heap()->noscript_shared_function_infos()),
+      current_script_(nullptr),
+      index_(-1) {
+  NextScript();
 }
 
+void SharedFunctionInfo::Iterator::NextScript() {
+  current_script_ = script_iterator_.Next();
+  if (current_script_ == nullptr) return;
+  index_ = 0;
+}
 
 SharedFunctionInfo* SharedFunctionInfo::Iterator::Next() {
-  do {
-    SharedFunctionInfo* next = sfi_iterator_.Next<SharedFunctionInfo>();
-    if (next != NULL) return next;
-  } while (NextScript());
-  return NULL;
+  SharedFunctionInfo* next = sfi_iterator_.Next<SharedFunctionInfo>();
+  if (next != nullptr) return next;
+  while (current_script_ != nullptr) {
+    FixedArray* infos = current_script_->shared_function_infos();
+    while (index_ < infos->length()) {
+      Object* info = infos->get(index_++);
+      if (!(info->IsSmi() || WeakCell::cast(info)->cleared())) {
+        return SharedFunctionInfo::cast(WeakCell::cast(info)->value());
+      }
+    }
+    NextScript();
+  }
+  return nullptr;
 }
 
 
@@ -13698,39 +13703,43 @@ void SharedFunctionInfo::SetScript(Handle<SharedFunctionInfo> shared,
   // 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);
+    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(),
+                                                 Smi::kZero);
+      }
     }
   } else {
     // Remove shared function info from root array.
@@ -13995,7 +14004,6 @@ void SharedFunctionInfo::InitFromFunctionLiteral(
   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(