Bug 251071

Summary: Fix IsoCellSet::remove()'s return value.
Product: WebKit Reporter: Mark Lam <mark.lam>
Component: JavaScriptCoreAssignee: Mark Lam <mark.lam>
Status: RESOLVED FIXED    
Severity: Normal CC: webkit-bug-importer, yijia_huang
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
See Also: https://bugs.webkit.org/show_bug.cgi?id=250847

Description Mark Lam 2023-01-23 23:57:56 PST 
In https://bugs.webkit.org/show_bug.cgi?id=250847, Yijia Huang found a bug in Bitmap::concurrentTestAndClear() where it's returning the inverse of its expected result.  Checking for all uses of concurrentTestAndClear(), we find that one result of IsoCellSet::remove() is also similarly incorrect.

This patch fixes these errors, and also adds comments to document the intended return values of some relevant functions, as well as the reasoning behind how some of the return values are computed.
Comment 1 Radar WebKit Bug Importer 2023-01-23 23:58:22 PST 
<rdar://problem/104590361>
Comment 2 Mark Lam 2023-01-24 00:07:18 PST 
Pull request: https://github.com/WebKit/WebKit/pull/9020
Comment 3 EWS 2023-01-24 09:32:55 PST 
Committed 259287@main (3589dd6fe569): <https://commits.webkit.org/259287@main>

Reviewed commits have been landed. Closing PR #9020 and removing active labels.