RESOLVED DUPLICATE of bug 20823 20984
convert masqueradeAsUndefined from a virtual function to a TypeInfo flag 
https://bugs.webkit.org/show_bug.cgi?id=20984
Summary convert masqueradeAsUndefined from a virtual function to a TypeInfo flag
Darin Adler
Reported 2008-09-21 21:33:37 PDT
We will convert masqueradeAsUndefined from a virtual function to a TypeInfo flag. Then we can make operations involving the flag faster.
Attachments
work in progress (17.02 KB, patch)
2008-09-21 21:34 PDT, Darin Adler 		no flags
DetailsFormatted DiffDiff
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Darin Adler
Comment 1 2008-09-21 21:34:25 PDT
Created attachment 23640 [details] work in progress Patch seems to work, but is not a speedup.
Gavin Barraclough
Comment 2 2008-09-22 04:42:35 PDT
We can probably turn this into a speedup by using it to allow us to JIT generate eq_null / neq_null. This is implemented in https://bugs.webkit.org/show_bug.cgi?id=20862 using a vptr hack – but broke a test in the webkit tests (never debugged – I'm guessing someone does subclass StringObjectThatMasqueradesAsUndefined, or there is another subclass that implements 'masqueradeAsUndefined()' – in which case the vptr hack won't have been safe).
Maciej Stachowiak
Comment 3 2008-09-22 06:31:23 PDT
did a version of this with the JIT logic, see bug 20823 *** This bug has been marked as a duplicate of 20823 ***
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