RESOLVED FIXED 225381
DisplayList::Recorder::ContextState::wasUsedForDrawing is unused and can probably be removed 
https://bugs.webkit.org/show_bug.cgi?id=225381
Summary DisplayList::Recorder::ContextState::wasUsedForDrawing is unused and can prob...
Cameron McCormack (:heycam)
Reported 2021-05-04 21:41:09 PDT
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Attachments
Patch (2.61 KB, patch)
2021-05-04 21:47 PDT, Cameron McCormack (:heycam) 		no flags
DetailsFormatted DiffDiff
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Cameron McCormack (:heycam)
Comment 1 2021-05-04 21:47:48 PDT
Created attachment 427732 [details] Patch
Said Abou-Hallawa
Comment 2 2021-05-05 11:36:07 PDT
This member was introduced in r194708 and its use was removed in r257958. Its original goal was to remove save/restore pair from DisplayList if no drawing happens in between. For example a sequence like this can be completed removed from the DisplayList since its replaying back has no effect: context.save(); context.setFillColor(Color::green); context.restore(); But the problem was in the Canvas case where calling the save() and restore() may happen in different frames. Recording a restore item may try to remove the last save item although the matching save item was pushed to the context of the ImageBuffer many frames earlier.
Cameron McCormack (:heycam)
Comment 3 2021-05-05 15:36:22 PDT
Thanks for the background. I did do a `grep -G wasUsedForDrawing` to check, but that didn't bring up the r257958 commit (since that removed a use of the `stateUsedForDrawing` local variable).
Cameron McCormack (:heycam)
Comment 4 2021-05-05 15:36:49 PDT
(In reply to Cameron McCormack (:heycam) from comment #3) > Thanks for the background. I did do a `grep -G wasUsedForDrawing` *git grep -G wasUsedForDrawing
EWS
Comment 5 2021-05-05 16:06:28 PDT
Committed r277050 (237360@main): <https://commits.webkit.org/237360@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 427732 [details].
Radar WebKit Bug Importer
Comment 6 2021-05-05 16:07:14 PDT
<rdar://problem/77580546>
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