[fastcall] fix options.data representation

The representation of `options.data` was previously refactored to
`v8::Value` when removing `v8::ApiObject`, but this is invalid for a
number of reasons (SMIs, v8::Value being a ZST, etc). To fix this, it
has been changed to `Local<Value>`, which also matches the
representation used for other fastcall parameters.

Bug: chromium:1052746
Change-Id: Ia4450bf3d908d4e1b7a85d6bd7ab45ea5f5f08f4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3844662Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: snek <snek@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82843}

include/v8-fast-api-calls.h

@@ -569,7 +569,7 @@ struct FastApiCallbackOptions {
    */
   union {
     uintptr_t data_ptr;
-    v8::Value data;
+    v8::Local<v8::Value> data;
   };
 
   /**

src/compiler/fast-api-calls.cc

@@ -309,11 +309,18 @@ Node* FastApiCallBuilder::Build(const FastApiCallFunctionVector& c_functions,
         stack_slot,
         static_cast<int>(offsetof(v8::FastApiCallbackOptions, fallback)),
         __ Int32Constant(0));
+
+    Node* data_stack_slot = __ StackSlot(sizeof(uintptr_t), alignof(uintptr_t));
+    __ Store(
+        StoreRepresentation(MachineType::PointerRepresentation(),
+                            kNoWriteBarrier),
+        data_stack_slot, 0, data_argument);
+
     __ Store(StoreRepresentation(MachineType::PointerRepresentation(),
                                  kNoWriteBarrier),
              stack_slot,
              static_cast<int>(offsetof(v8::FastApiCallbackOptions, data)),
-             data_argument);
+             data_stack_slot);
 
     initialize_options_(stack_slot);
 

test/cctest/test-api.cc

@@ -27625,9 +27625,8 @@ struct BasicApiChecker {
   static Ret FastCallback(v8::Local<v8::Object> receiver, Value argument,
                           v8::FastApiCallbackOptions& options) {
     // TODO(mslekova): Refactor the data checking.
-    v8::Value* data = &(options.data);
-    CHECK(data->IsNumber());
-    CHECK_EQ(v8::Number::Cast(data)->Value(), 42.0);
+    CHECK(options.data->IsNumber());
+    CHECK_EQ(Local<v8::Number>::Cast(options.data)->Value(), 42.5);
     return Impl::FastCallback(receiver, argument, options);
   }
   static Ret FastCallbackNoFallback(v8::Local<v8::Object> receiver,
@@ -27859,7 +27858,7 @@ bool SetupTest(v8::Local<v8::Value> initial_value, LocalContext* env,
 
   Local<v8::FunctionTemplate> checker_templ = v8::FunctionTemplate::New(
       isolate, BasicApiChecker<Value, Impl, Ret>::SlowCallback,
-      v8::Number::New(isolate, 42), v8::Local<v8::Signature>(), 1,
+      v8::Number::New(isolate, 42.5), v8::Local<v8::Signature>(), 1,
       v8::ConstructorBehavior::kThrow, v8::SideEffectType::kHasSideEffect,
       &c_func);
   if (!accept_any_receiver) {