[wasm] Move weak list of instances from module to Script.

This moves the weak list of instances from {WasmModuleObject} to the
corresponding {Script} object. The list is used solely for breakpoints
which are intended to affect all instances belonging to a given script,
hence the new placement of the list is a preparation to fully support
per-script breakpoints.

R=clemensb@chromium.org
BUG=v8:6847,chromium:893069

Change-Id: I52315e0ba1e5e5021f55bf05d8cb0f01bf9f0fbb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1847359
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64191}

src/builtins/base.tq

@@ -1593,7 +1593,6 @@ extern class WasmModuleObject extends JSObject {
   native_module: Foreign;
   export_wrappers: FixedArray;
   script: Script;
-  weak_instance_list: WeakArrayList;
   asm_js_offset_table: ByteArray | Undefined;
   break_point_infos: FixedArray | Undefined;
 }

src/objects/script-inl.h

@@ -36,8 +36,6 @@ ACCESSORS_CHECKED(Script, eval_from_shared_or_wrapped_arguments, Object,
                   this->type() != TYPE_WASM)
 SMI_ACCESSORS_CHECKED(Script, eval_from_position, kEvalFromPositionOffset,
                       this->type() != TYPE_WASM)
-ACCESSORS(Script, shared_function_infos, WeakFixedArray,
-          kSharedFunctionInfosOffset)
 SMI_ACCESSORS(Script, flags, kFlagsOffset)
 ACCESSORS(Script, source_url, Object, kSourceUrlOffset)
 ACCESSORS(Script, source_mapping_url, Object, kSourceMappingUrlOffset)
@@ -47,6 +45,8 @@ ACCESSORS_CHECKED(Script, wasm_module_object, Object,
                   this->type() == TYPE_WASM)
 ACCESSORS_CHECKED(Script, wasm_managed_native_module, Object,
                   kEvalFromPositionOffset, this->type() == TYPE_WASM)
+ACCESSORS_CHECKED(Script, wasm_weak_instance_list, WeakArrayList,
+                  kSharedFunctionInfosOffset, this->type() == TYPE_WASM)
 
 bool Script::is_wrapped() const {
   return eval_from_shared_or_wrapped_arguments().IsFixedArray();
@@ -77,6 +77,20 @@ FixedArray Script::wrapped_arguments() const {
   return FixedArray::cast(eval_from_shared_or_wrapped_arguments());
 }
 
+DEF_GETTER(Script, shared_function_infos, WeakFixedArray) {
+  return type() == TYPE_WASM
+             ? ReadOnlyRoots(GetHeap()).empty_weak_fixed_array()
+             : TaggedField<WeakFixedArray, kSharedFunctionInfosOffset>::load(
+                   *this);
+}
+
+void Script::set_shared_function_infos(WeakFixedArray value,
+                                       WriteBarrierMode mode) {
+  DCHECK_NE(TYPE_WASM, type());
+  TaggedField<WeakFixedArray, kSharedFunctionInfosOffset>::store(*this, value);
+  CONDITIONAL_WRITE_BARRIER(*this, kSharedFunctionInfosOffset, value, mode);
+}
+
 wasm::NativeModule* Script::wasm_native_module() const {
   return Managed<wasm::NativeModule>::cast(wasm_managed_native_module()).raw();
 }

src/objects/script.h

@@ -112,6 +112,11 @@ class Script : public Struct {
   DECL_ACCESSORS(wasm_managed_native_module, Object)
   inline wasm::NativeModule* wasm_native_module() const;
 
+  // [wasm_weak_instance_list]: the list of all {WasmInstanceObject} being
+  // affected by breakpoints that are managed via this script.
+  // This must only be called if the type of this script is TYPE_WASM.
+  DECL_ACCESSORS(wasm_weak_instance_list, WeakArrayList)
+
   // [host_defined_options]: Options defined by the embedder.
   DECL_ACCESSORS(host_defined_options, FixedArray)
 

src/runtime/runtime-test.cc

@@ -1259,7 +1259,8 @@ RUNTIME_FUNCTION(Runtime_WasmGetNumberOfInstances) {
   DCHECK_EQ(1, args.length());
   CONVERT_ARG_HANDLE_CHECKED(WasmModuleObject, module_obj, 0);
   int instance_count = 0;
-  WeakArrayList weak_instance_list = module_obj->weak_instance_list();
+  WeakArrayList weak_instance_list =
+      module_obj->script().wasm_weak_instance_list();
   for (int i = 0; i < weak_instance_list.length(); ++i) {
     if (weak_instance_list.Get(i)->IsWeak()) instance_count++;
   }

src/wasm/wasm-objects-inl.h

@@ -88,8 +88,6 @@ ACCESSORS(WasmModuleObject, managed_native_module, Managed<wasm::NativeModule>,
           kNativeModuleOffset)
 ACCESSORS(WasmModuleObject, export_wrappers, FixedArray, kExportWrappersOffset)
 ACCESSORS(WasmModuleObject, script, Script, kScriptOffset)
-ACCESSORS(WasmModuleObject, weak_instance_list, WeakArrayList,
-          kWeakInstanceListOffset)
 OPTIONAL_ACCESSORS(WasmModuleObject, asm_js_offset_table, ByteArray,
                    kAsmJsOffsetTableOffset)
 OPTIONAL_ACCESSORS(WasmModuleObject, breakpoint_infos, FixedArray,

src/wasm/wasm-objects.cc

@@ -244,10 +244,10 @@ Handle<WasmModuleObject> WasmModuleObject::New(
   if (script->type() == Script::TYPE_WASM) {
     script->set_wasm_module_object(*module_object);
     script->set_wasm_managed_native_module(*managed_native_module);
+    script->set_wasm_weak_instance_list(
+        ReadOnlyRoots(isolate).empty_weak_array_list());
   }
   module_object->set_script(*script);
-  module_object->set_weak_instance_list(
-      ReadOnlyRoots(isolate).empty_weak_array_list());
   module_object->set_managed_native_module(*managed_native_module);
   return module_object;
 }
@@ -273,10 +273,10 @@ bool WasmModuleObject::SetBreakPoint(Handle<WasmModuleObject> module_object,
   // Insert new break point into break_positions of module object.
   WasmModuleObject::AddBreakpointToInfo(module_object, *position, break_point);
 
-  // Iterate over all instances of this module and tell them to set this new
-  // breakpoint. We do this using the weak list of all instances.
-  Handle<WeakArrayList> weak_instance_list(module_object->weak_instance_list(),
-                                           isolate);
+  // Iterate over all instances and tell them to set this new breakpoint.
+  // We do this using the weak list of all instances from the script.
+  Handle<WeakArrayList> weak_instance_list(
+      module_object->script().wasm_weak_instance_list(), isolate);
   for (int i = 0; i < weak_instance_list->length(); ++i) {
     MaybeObject maybe_instance = weak_instance_list->Get(i);
     if (maybe_instance->IsWeak()) {
@@ -310,10 +310,10 @@ bool WasmModuleObject::ClearBreakPoint(Handle<WasmModuleObject> module_object,
     return false;
   }
 
-  // Iterate over all instances of this module and tell them to remove this
-  // breakpoint. We do this using the weak list of all instances.
-  Handle<WeakArrayList> weak_instance_list(module_object->weak_instance_list(),
-                                           isolate);
+  // Iterate over all instances and tell them to remove this breakpoint.
+  // We do this using the weak list of all instances from the script.
+  Handle<WeakArrayList> weak_instance_list(
+      module_object->script().wasm_weak_instance_list(), isolate);
   for (int i = 0; i < weak_instance_list->length(); ++i) {
     MaybeObject maybe_instance = weak_instance_list->Get(i);
     if (maybe_instance->IsWeak()) {
@@ -1687,13 +1687,16 @@ Handle<WasmInstanceObject> WasmInstanceObject::New(
   instance->set_jump_table_start(
       module_object->native_module()->jump_table_start());
 
-  // Insert the new instance into the modules weak list of instances.
+  // Insert the new instance into the scripts weak list of instances. This list
+  // is used for breakpoints affecting all instances belonging to the script.
   // TODO(mstarzinger): Allow to reuse holes in the {WeakArrayList} below.
-  Handle<WeakArrayList> weak_instance_list(module_object->weak_instance_list(),
-                                           isolate);
-  weak_instance_list = WeakArrayList::AddToEnd(
-      isolate, weak_instance_list, MaybeObjectHandle::Weak(instance));
-  module_object->set_weak_instance_list(*weak_instance_list);
+  if (module_object->script().type() == Script::TYPE_WASM) {
+    Handle<WeakArrayList> weak_instance_list(
+        module_object->script().wasm_weak_instance_list(), isolate);
+    weak_instance_list = WeakArrayList::AddToEnd(
+        isolate, weak_instance_list, MaybeObjectHandle::Weak(instance));
+    module_object->script().set_wasm_weak_instance_list(*weak_instance_list);
+  }
 
   InitDataSegmentArrays(instance, module_object);
   InitElemSegmentArrays(instance, module_object);

src/wasm/wasm-objects.h

@@ -126,7 +126,6 @@ class WasmModuleObject : public JSObject {
   DECL_ACCESSORS(managed_native_module, Managed<wasm::NativeModule>)
   DECL_ACCESSORS(export_wrappers, FixedArray)
   DECL_ACCESSORS(script, Script)
-  DECL_ACCESSORS(weak_instance_list, WeakArrayList)
   DECL_OPTIONAL_ACCESSORS(asm_js_offset_table, ByteArray)
   DECL_OPTIONAL_ACCESSORS(breakpoint_infos, FixedArray)
   inline wasm::NativeModule* native_module() const;