Bug 151453 – Caching of properties on objects that have named property getters is sometimes incorrect

• Status: RESOLVED
• Resolution: FIXED
• Component: Bindings

[Chris Dumez]

Caching of properties on objects that have named property getters is sometimes incorrect.

[Chris Dumez]

rdar://problem/23049343

[Chris Dumez]

Created attachment 265878 [details]
WIP (Not working yet)

[Chris Dumez]

Created attachment 265879 [details]
WIP (Not working yet)

[Chris Dumez]

Created attachment 265898 [details]
Patch

[Gavin Barraclough]

Comment on attachment 265898 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=265898&action=review

> Source/JavaScriptCore/runtime/JSTypeInfo.h:53
> +static const unsigned GetOwnPropertySlotIsImpureForPropertyAbsence = 1 << 13;

One suggestion:

GetOwnPropertySlotIsImpure implies GetOwnPropertySlotIsImpureForPropertyAbsence, but does not cause it to be set. A programmer could in error check GetOwnPropertySlotIsImpureForPropertyAbsence and think this would tell them whether property access is impure for absence – but this is not sufficient (they also need to check GetOwnPropertySlotIsImpure).

As such a better approach might be to have discrete flags – where one is not a subset of another – GetOwnPropertySlotIsImpureForPropertyAbsence and GetOwnPropertySlotIsImpureForPropertyPresence. You could define GetOwnPropertySlotIsImpure to set both (GetOwnPropertySlotIsImpureForPropertyAbsence | GetOwnPropertySlotIsImpureForPropertyPresence).

Classes wanting to adopt both behaviors could still use the GetOwnPropertySlotIsImpure name, but code wanting to check could safely either check …ForPropertyAbsence or …ForPropertyPresence.

> LayoutTests/fast/dom/NamedNodeMap-named-getter-caching.html:16
> +        lastIterationHasRightValue = true;

This loop now only detects a bad value on the last iteration, no longer checks values on the first 999 interactions are as expected too. Please fix.

[Chris Dumez]

Created attachment 265977 [details]
Patch

[WebKit Commit Bot]

Comment on attachment 265977 [details]
Patch

Clearing flags on attachment: 265977

Committed r192693: <http://trac.webkit.org/changeset/192693>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.