[Webkit-unassigned] [Bug 186459] [DFG] Fold GetByVal if Array is CoW

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=186459

--- Comment #1 from Yusuke Suzuki <utatane.tea at gmail.com> ---
(In reply to Yusuke Suzuki from comment #0)
> If we know the array is a constant one and it has a CoW structure (by
> CheckStructure etc.), InBounds GetByVal can be turned into a constant.

Does this happen? => I think it can happen. For example, we have a global variable, which is an array in a literal form.
And some functions access it. At that time,

1. GlobalVar access can be folded into a constant if it is not changed.
2. GetByVal can emit CheckStructure
3. Then, we have a GetByVal with a constant JSArray with JSImmutableButterfly!

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