From 309f254c2c8c590a2655972aa1b31d020777634c Mon Sep 17 00:00:00 2001
From: Karl Seguin <k@openmymind.io>
Date: Fri, 13 Feb 2026 14:12:43 +0800
Subject: [PATCH] Optimize toa storage in v8 object.

We're currently using Get/SetInternalField to store our toa instance in v8. This
appears to be meant for v8 data itself, as it participates in the GC's
referencing counting. This is a bit obvious by the fact that it expects a
v8::Data, we we're able to do by wrapping our toa into a v8::External.

The Get/SetAlignedPointerFromInternalField seem specifically designed for toa,
as it takes a (void *) (thus, not requiring the external wrapper) and, from what
I understand is more efficient (presumably because the GC ignores it).

Depends on: https://github.com/lightpanda-io/zig-v8-fork/pull/149
---
 src/browser/js/Env.zig          | 8 ++++++++
 src/browser/js/Inspector.zig    | 5 ++---
 src/browser/js/Local.zig        | 6 +-----
 src/browser/js/TaggedOpaque.zig | 4 ++--
 4 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/src/browser/js/Env.zig b/src/browser/js/Env.zig
index c73450a8..8f2cc6aa 100644
--- a/src/browser/js/Env.zig
+++ b/src/browser/js/Env.zig
@@ -78,6 +78,14 @@ pub const InitOpts = struct {
 };
 
 pub fn init(app: *App, opts: InitOpts) !Env {
+    if (comptime IS_DEBUG) {
+        comptime {
+            // V8 requirement for any data using SetAlignedPointerInInternalField
+            const a = @alignOf(@import("TaggedOpaque.zig"));
+            std.debug.assert(a >= 2 and a % 2 == 0);
+        }
+    }
+
     const allocator = app.allocator;
     const snapshot = &app.snapshot;
 
diff --git a/src/browser/js/Inspector.zig b/src/browser/js/Inspector.zig
index 7ba97257..245c5582 100644
--- a/src/browser/js/Inspector.zig
+++ b/src/browser/js/Inspector.zig
@@ -364,9 +364,8 @@ pub fn getTaggedOpaque(value: *const v8.Value) ?*TaggedOpaque {
         return null;
     }
 
-    const external_value = v8.v8__Object__GetInternalField(value, 0).?;
-    const external_data = v8.v8__External__Value(external_value).?;
-    return @ptrCast(@alignCast(external_data));
+    const tao_ptr = v8.v8__Object__GetAlignedPointerFromInternalField(value, 0).?;
+    return @ptrCast(@alignCast(tao_ptr));
 }
 
 fn cZigStringToString(s: v8.CZigString) ?[]const u8 {
diff --git a/src/browser/js/Local.zig b/src/browser/js/Local.zig
index 524dfd54..78ec45b0 100644
--- a/src/browser/js/Local.zig
+++ b/src/browser/js/Local.zig
@@ -181,11 +181,7 @@ pub fn mapZigInstanceToJs(self: *const Local, js_obj_handle: ?*const v8.Object,
                     .subtype = if (@hasDecl(JsApi.Meta, "subtype")) JsApi.Meta.subype else .node,
                 };
 
-                // Skip setting internal field for the global object (Window)
-                // Window accessors get the instance from context.page.window instead
-                // if (resolved.class_id != @import("../webapi/Window.zig").JsApi.Meta.class_id) {
-                v8.v8__Object__SetInternalField(js_obj.handle, 0, isolate.createExternal(tao));
-                // }
+                v8.v8__Object__SetAlignedPointerInInternalField(js_obj.handle, 0, tao);
             } else {
                 // If the struct is empty, we don't need to do all
                 // the TOA stuff and setting the internal data.
diff --git a/src/browser/js/TaggedOpaque.zig b/src/browser/js/TaggedOpaque.zig
index 68224b64..d62e735b 100644
--- a/src/browser/js/TaggedOpaque.zig
+++ b/src/browser/js/TaggedOpaque.zig
@@ -133,8 +133,8 @@ pub fn fromJS(comptime R: type, js_obj_handle: *const v8.Object) !R {
         @compileError("unknown Zig type: " ++ @typeName(R));
     }
 
-    const internal_field_handle = v8.v8__Object__GetInternalField(js_obj_handle, 0).?;
-    const tao: *TaggedOpaque = @ptrCast(@alignCast(v8.v8__External__Value(internal_field_handle)));
+    const tao_ptr = v8.v8__Object__GetAlignedPointerFromInternalField(js_obj_handle, 0).?;
+    const tao: *TaggedOpaque = @ptrCast(@alignCast(tao_ptr));
     const expected_type_index = bridge.JsApiLookup.getId(JsApi);
 
     const prototype_chain = tao.prototype_chain[0..tao.prototype_len];