From 08e1a1c361dac554906f07fa0880c00d182d04a8 Mon Sep 17 00:00:00 2001
From: Divy Srivastava <dj.srivastava23@gmail.com>
Date: Wed, 13 Jul 2022 12:35:31 +0530
Subject: [PATCH] Add v8::Object
 `[Get/Set]AlignedPointer[From/In]InternalField` (#1026)

---
 src/binding.cc    | 10 ++++++
 src/object.rs     | 33 +++++++++++++++++
 tests/test_api.rs | 92 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 135 insertions(+)

diff --git a/src/binding.cc b/src/binding.cc
index 1ff045b9..934ee6cb 100644
--- a/src/binding.cc
+++ b/src/binding.cc
@@ -1165,6 +1165,16 @@ const v8::Value* v8__Object__GetIndex(const v8::Object& self,
       ptr_to_local(&self)->Get(ptr_to_local(&context), index));
 }
 
+void* v8__Object__GetAlignedPointerFromInternalField(const v8::Object& self,
+                                                      int index) {
+  return ptr_to_local(&self)->GetAlignedPointerFromInternalField(index);
+}
+
+void v8__Object__SetAlignedPointerInInternalField(const v8::Object& self,
+                                                   int index, void* value) {
+  ptr_to_local(&self)->SetAlignedPointerInInternalField(index, value);
+}
+
 const v8::Value* v8__Object__GetPrototype(const v8::Object& self) {
   return local_to_ptr(ptr_to_local(&self)->GetPrototype());
 }
diff --git a/src/object.rs b/src/object.rs
index cd6614da..bf8af59d 100644
--- a/src/object.rs
+++ b/src/object.rs
@@ -1,3 +1,5 @@
+use libc::c_void;
+
 use crate::isolate::Isolate;
 use crate::support::int;
 use crate::support::MapFnTo;
@@ -120,6 +122,15 @@ extern "C" {
     this: *const Object,
     index: int,
   ) -> *const Value;
+  fn v8__Object__GetAlignedPointerFromInternalField(
+    this: *const Object,
+    index: int,
+  ) -> *const c_void;
+  fn v8__Object__SetAlignedPointerInInternalField(
+    this: *const Object,
+    index: int,
+    value: *const c_void,
+  );
   fn v8__Object__SetIntegrityLevel(
     this: *const Object,
     context: *const Context,
@@ -512,6 +523,28 @@ impl Object {
     None
   }
 
+  /// Gets a 2-byte-aligned native pointer from an internal field.
+  ///
+  /// # Safety
+  /// This field must have been set by SetAlignedPointerInInternalField, everything else leads to undefined behavior.
+  pub unsafe fn get_aligned_pointer_from_internal_field(
+    &self,
+    index: i32,
+  ) -> *const c_void {
+    v8__Object__GetAlignedPointerFromInternalField(self, index)
+  }
+
+  /// Sets a 2-byte-aligned native pointer in an internal field.
+  /// To retrieve such a field, GetAlignedPointerFromInternalField must be used.
+  #[allow(clippy::not_unsafe_ptr_arg_deref)]
+  pub fn set_aligned_pointer_in_internal_field(
+    &self,
+    index: i32,
+    value: *const c_void,
+  ) {
+    unsafe { v8__Object__SetAlignedPointerInInternalField(self, index, value) }
+  }
+
   /// Sets the integrity level of the object.
   pub fn set_integrity_level(
     &self,
diff --git a/tests/test_api.rs b/tests/test_api.rs
index 11d03e68..eb4b5d95 100644
--- a/tests/test_api.rs
+++ b/tests/test_api.rs
@@ -7247,3 +7247,95 @@ fn test_fast_calls_arraybuffer() {
   eval(scope, source).unwrap();
   assert_eq!("fast", unsafe { WHO });
 }
+
+#[test]
+fn test_fast_calls_reciever() {
+  const V8_WRAPPER_TYPE_INDEX: i32 = 0;
+  const V8_WRAPPER_OBJECT_INDEX: i32 = 1;
+
+  static mut WHO: &str = "none";
+  fn fast_fn(recv: v8::Local<v8::Object>) -> u32 {
+    unsafe {
+      WHO = "fast";
+      let embedder_obj =
+        recv.get_aligned_pointer_from_internal_field(V8_WRAPPER_OBJECT_INDEX);
+
+      let i = *(embedder_obj as *const u32);
+      assert_eq!(i, 69);
+      i
+    }
+  }
+
+  pub struct FastTest;
+  impl fast_api::FastFunction for FastTest {
+    fn args(&self) -> &'static [fast_api::Type] {
+      &[fast_api::Type::V8Value]
+    }
+
+    fn return_type(&self) -> fast_api::CType {
+      fast_api::CType::Uint32
+    }
+
+    type Signature = fn(receiver: v8::Local<v8::Object>) -> u32;
+    fn function(&self) -> Self::Signature {
+      fast_fn
+    }
+  }
+
+  fn slow_fn(
+    scope: &mut v8::HandleScope,
+    _: v8::FunctionCallbackArguments,
+    mut rv: v8::ReturnValue,
+  ) {
+    unsafe { WHO = "slow" };
+    rv.set(v8::Boolean::new(scope, false).into());
+  }
+
+  let _setup_guard = setup();
+  let isolate = &mut v8::Isolate::new(
+    v8::CreateParams::default().embedder_wrapper_type_info_offsets(
+      V8_WRAPPER_TYPE_INDEX,
+      V8_WRAPPER_OBJECT_INDEX,
+    ),
+  );
+  let scope = &mut v8::HandleScope::new(isolate);
+  let context = v8::Context::new(scope);
+  let scope = &mut v8::ContextScope::new(scope, context);
+
+  let object_template = v8::ObjectTemplate::new(scope);
+  assert!(object_template
+    .set_internal_field_count((V8_WRAPPER_OBJECT_INDEX + 1) as usize));
+
+  let obj = object_template.new_instance(scope).unwrap();
+  let embedder_obj = Box::into_raw(Box::new(69u32));
+  obj.set_aligned_pointer_in_internal_field(
+    V8_WRAPPER_OBJECT_INDEX,
+    embedder_obj as _,
+  );
+
+  let template =
+    v8::FunctionTemplate::builder(slow_fn).build_fast(scope, FastTest);
+
+  let name = v8::String::new(scope, "method").unwrap();
+  let value = template.get_function(scope).unwrap();
+  obj.set(scope, name.into(), value.into()).unwrap();
+
+  let obj_str = v8::String::new(scope, "obj").unwrap();
+  let global = context.global(scope);
+  global.set(scope, obj_str.into(), obj.into()).unwrap();
+
+  let source = r#"
+  function f() { return obj.method(); }
+  %PrepareFunctionForOptimization(f);
+  f();
+"#;
+  eval(scope, source).unwrap();
+  assert_eq!("slow", unsafe { WHO });
+
+  let source = r#"
+    %OptimizeFunctionOnNextCall(f);
+    f();
+  "#;
+  eval(scope, source).unwrap();
+  assert_eq!("fast", unsafe { WHO });
+}