[Webkit-unassigned] [Bug 143996] New: [[Set]] should be properly executed in JS builtins

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=143996

            Bug ID: 143996
           Summary: [[Set]] should be properly executed in JS builtins
    Classification: Unclassified
           Product: WebKit
           Version: 528+ (Nightly build)
          Hardware: Unspecified
                OS: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: JavaScriptCore
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: utatane.tea at gmail.com

Currently, all assignments in builtins JS code is compiled into put_by_val_direct.
However, some functions (like Array.from) needs [[Set]]. (but it is now compiled into pu_by_val_direct, [[DefineOwnProperty]]).

By leveraging bytecode intrinsics, we'll fix it.
There's 2 plans to solve this.

1. Implement the bytecode intrinsic for [[DefineOwnProperty]] and remove the hack for builtins

Currently, assignments in builtins JS code are compiled into put_by_val_direct.
However, it's different from the default JS behavior.
In this plan, we implement the bytecode intrinsic emitting put_by_val_direct and use it explicitly.
And dropping the current hack for builtins.

2. Implement the bytecode intrinsic for [[Set]] and keep the current hack for builtins

However, a lot of builtins code requires [[DefineOwnProperty]] behavior rather than [[Set]].
So keeping the current hack for builtins. By default, assignments in builtins are compiled into put_by_val_direct.
And implementing the bytecode intrinsic emitting put_by_val ([[Set]])

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