Bug 214231 – [JSC] Avoid JSString creation in Intl.Locale#{minimize,maximize}

• Status: RESOLVED
• Resolution: FIXED
• Component: New Bugs

[Yusuke Suzuki]

[JSC] Avoid JSString creation in Intl.Locale#{minimize,maximize}

[Yusuke Suzuki]

Created attachment 404088 [details]
Patch

[Yusuke Suzuki]

Created attachment 404089 [details]
Patch

[Yusuke Suzuki]

Comment on attachment 404089 [details]
Patch

Thanks!

[EWS]

Committed r264285: <https://trac.webkit.org/changeset/264285>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 404089 [details].

[Radar WebKit Bug Importer]

<rdar://problem/65441234>

[Darin Adler]

Comment on attachment 404089 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=404089&action=review

> Source/JavaScriptCore/runtime/IntlLocale.cpp:221
>      String tag = tagValue.inherits<IntlLocale>(vm) ? jsCast<IntlLocale*>(tagValue)->toString() : tagValue.toWTFString(globalObject);

Is calling IntlLocale::toString better than just calling toWTFString on the tag value? Is the special case here important for correctness? Performance?

[Yusuke Suzuki]

Comment on attachment 404089 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=404089&action=review

>> Source/JavaScriptCore/runtime/IntlLocale.cpp:221
>>      String tag = tagValue.inherits<IntlLocale>(vm) ? jsCast<IntlLocale*>(tagValue)->toString() : tagValue.toWTFString(globalObject);
> 
> Is calling IntlLocale::toString better than just calling toWTFString on the tag value? Is the special case here important for correctness? Performance?

This is important for correctness, and also improves the performance.
According to the spec, here is special case. https://tc39.es/ecma402/#sec-Intl.Locale

8. If Type(tag) is Object and tag has an [[InitializedLocale]] internal slot, then
8.a Let tag be tag.[[Locale]].

This means that even if the given locale object has its own `toString` user defined method, initializeLocale should ignore calling this function and instead retrieve toString result from Locale's field directly.
And it also improves the performance since we do not need to invoke `toString` JS function here.