Bug 193390

Summary:	Why is the result of FontCascadeFonts::glyphDataForSystemFallback() not kept in the cache?
Product:	WebKit	Reporter:	Simon Fraser (smfr) <simon.fraser>
Component:	Text	Assignee:	Nobody <webkit-unassigned>
Status:	NEW ---
Severity:	Normal	CC:	mmaxfield, simon.fraser
Priority:	P2
Version:	WebKit Nightly Build
Hardware:	Unspecified
OS:	Unspecified

Description Simon Fraser (smfr) 2019-01-13 18:29:21 PST

When running this subtest of Speedometer2: https://browserbench.org/Speedometer2.0/?suite=BackboneJS-TodoMVC&iterationCount=100
we enter FontCascadeFonts::glyphDataForSystemFallback() multiple times, each time for the same glyph (&#10095; Heavy Right-Pointing Angle Quotation Mark Ornament).

The caller, FontCascadeFonts::glyphDataForCharacter(), puts the resulting glyph in the cache, but later on we go through glyphDataForSystemFallback() again and I'm not sure why.

Comment 1 Simon Fraser (smfr) 2019-01-13 18:31:23 PST

We spend 34ms in 34.00 ms in FontCascadeFonts::glyphDataForSystemFallback() during a 15s run.