revert as workaround for compiler error with old clang < 17
commit ce71348a09f6689dd01a68db64b172191d0182d8
Author: Andrey Kosyakov <caseq@chromium.org>
Date: Thu Dec 21 18:38:38 2023 +0000
[bindings] Use v8::Array::Iterate for converting script wrappables
This changes CreateIDLSequenceFromV8Array to use the new
v8::Array::Iterate() operation.
This speeds up the "execBundles" part of the microbenchmark
at crbug.com/dawn/1858 by around 3x.
This depends on crrev.com/c/4846594 landing (and rolling) first.
This is a slight re-work of https://crrev.com/c/4847447/3,
originally by jkummerow@chromium.org
Bug: v8:14218, dawn:1858, 1511239
Change-Id: Ia266556d05b4d53e6942e12609d1c08882b4ff0f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5132129
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1240236}
--- a/third_party/blink/renderer/bindings/core/v8/native_value_traits.h 2024-05-13 20:23:41.165774029 +0200
+++ b/third_party/blink/renderer/bindings/core/v8/native_value_traits.h 2024-05-13 20:27:58.994663485 +0200
@@ -110,12 +110,6 @@ struct NativeValueTraitsBase<
static constexpr bool has_null_value =
bindings::NativeValueTraitsHasNullValue<ImplType>::value;
- // This should only be true for certain subclasses of ScriptWrappable
- // that satisfy the assumptions of CreateIDLSequenceFromV8ArraySlow() with
- // regards to how NativeValue() is implemented for the underlying type.
- static constexpr bool supports_scriptwrappable_specific_fast_array_iteration =
- false;
-
template <typename... ExtraArgs>
static decltype(auto) ArgumentValue(v8::Isolate* isolate,
int argument_index,
--- a/third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h 2024-05-13 20:23:47.295915837 +0200
+++ b/third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h 2024-05-13 20:27:21.649808564 +0200
@@ -1050,87 +1050,11 @@ CreateIDLSequenceFromV8ArraySlow(v8::Iso
return {};
}
- using ResultType = typename NativeValueTraits<IDLSequence<T>>::ImplType;
- ResultType result;
+ typename NativeValueTraits<IDLSequence<T>>::ImplType result;
result.ReserveInitialCapacity(length);
v8::Local<v8::Context> current_context = isolate->GetCurrentContext();
v8::TryCatch try_block(isolate);
- // Fast path -- we're creating a sequence of script wrappables, which can be
- // done by directly getting underlying object as long as array types are
- // homogeneous. With ScriptWrappables, we don't expect to enter JS during
- // iteration, so we can rely on v8::Array::Iterate() which is much faster than
- // iterating an array on the client side of the v8. Additionally, for most
- // subsptyes of ScriptWrappables, we can speed up type checks (see more on
- // that below next to supports_scriptwrappable_specific_fast_array_iteration
- // check.
- if constexpr (std::is_base_of_v<ScriptWrappable, T>) {
- struct CallbackData {
- STACK_ALLOCATED();
-
- public:
- v8::Isolate* isolate;
- v8::TypecheckWitness witness;
- ResultType& result;
- ExceptionState& exception_state;
- CallbackData(v8::Isolate* isolate,
- ResultType& result,
- ExceptionState& exception_state)
- : isolate(isolate),
- witness(isolate),
- result(result),
- exception_state(exception_state) {}
- };
-
- CallbackData callback_data(isolate, result, exception_state);
- v8::Array::IterationCallback callback = [](uint32_t index,
- v8::Local<v8::Value> v8_element,
- void* data) {
- CallbackData* callback_data = reinterpret_cast<CallbackData*>(data);
- v8::Isolate* isolate = callback_data->isolate;
- // 3.4. Initialize Si to the result of converting nextItem to an IDL value
- // of type T.
- v8::TypecheckWitness& witness = callback_data->witness;
- // We can speed up type check by taking advantage of V8's type witness,
- // provided traits' NativeValue implementation doesn't have additional
- // logic beyond checking the type and calling ToScriptWrappable().
- if constexpr (
- NativeValueTraits<
- T>::supports_scriptwrappable_specific_fast_array_iteration) {
- if (witness.Matches(v8_element)) {
- auto&& value = ToScriptWrappable(isolate, v8_element.As<v8::Object>())
- ->template ToImpl<T>();
- callback_data->result.push_back(std::move(value));
- return v8::Array::CallbackResult::kContinue;
- }
- }
- auto&& element = NativeValueTraits<T>::NativeValue(
- isolate, v8_element, callback_data->exception_state);
- if (callback_data->exception_state.HadException()) {
- // It doesn't matter whether we return `kException` or `kBreak` here,
- // as that only affects the return value of `v8_array->Iterate()`,
- // which we are ignoring.
- return v8::Array::CallbackResult::kException;
- }
- if constexpr (
- NativeValueTraits<
- T>::supports_scriptwrappable_specific_fast_array_iteration) {
- witness.Update(v8_element);
- }
- callback_data->result.push_back(std::move(element));
- return v8::Array::CallbackResult::kContinue;
- };
- if (!v8_array->Iterate(current_context, callback, &callback_data)
- .IsJust()) {
- if (try_block.HasCaught()) {
- exception_state.RethrowV8Exception(try_block.Exception());
- }
- DCHECK(exception_state.HadException());
- return {};
- }
- return result;
- }
-
// Array length may change if array is mutated during iteration.
for (uint32_t i = 0; i < v8_array->Length(); ++i) {
v8::Local<v8::Value> v8_element;
@@ -1590,12 +1514,6 @@ struct NativeValueTraits<
T,
typename std::enable_if_t<std::is_base_of<ScriptWrappable, T>::value>>
: public NativeValueTraitsBase<T*> {
- // This signifies that CreateIDLSequenceFromV8ArraySlow() may apply
- // certain optimization based on assumptions about `NativeValue()`
- // implementation below. For subclasses of ScriptWrappable that have
- // different implementation of NativeValue(), this should remain false.
- static constexpr bool supports_scriptwrappable_specific_fast_array_iteration =
- true;
static inline T* NativeValue(v8::Isolate* isolate,
v8::Local<v8::Value> value,