457048 - TM: Always give global object a unique shape id.

Status: RESOLVED INCOMPLETE

(Core :: JavaScript Engine, defect, P3)

Description

[Andreas Gal :gal]

This would help any path where we have to make sure the global object is not aliased. Along most paths we already guard the shape, so we wouldn't have to guard for the alias.

Comment 1

[Brendan Eich [:brendan]]

Not sure we need this -- see bug 456810 comment 6.

Giving the global a unique shape when it's set as the global object would regenerate its shape on every property add. This could be ok, but would tend to waste shape ids. Not sure of other downside.

Assigning a unique shape on start of recording would purge the global entries in the property cache, which would hurt performance.

/be

Comment 2

[Brendan Eich [:brendan]]

We don't need this without evidence of objects accessed by element ops having the same shape as the global object. Marking INCOMPLETE for want of evidence, reopen if we get some.

/be