Bug 182157 – [YarrJIT][ARM] We need to save r8 as it is the initial start register

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Guillaume Emont]

We still need to keep on saving r6 as it is used by the MacroAssembler, which we use (we get crashes in some situations otherwise).

This issue was discovered because stress/regress-174044.js crashes on a raspberry pi 2 when compiled in -O2.

[Guillaume Emont]

Created attachment 332334 [details]
Patch

Patch fixing the issue.

[Saam Barati]

Comment on attachment 332334 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=332334&action=review

> Source/JavaScriptCore/ChangeLog:8
> +        We still need to keep on saving r6 as it is used by the MacroAssembler

you mean r8, not r6?

[Guillaume Emont]

Comment on attachment 332334 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=332334&action=review

>> Source/JavaScriptCore/ChangeLog:8
>> +        We still need to keep on saving r6 as it is used by the MacroAssembler
> 
> you mean r8, not r6?

Sorry, I meant that in addition to saving $r8, as the title suggest, we can't stop saving $r6, as I initially wrongly deducted in a first version of the patch that was creating weird crashes :). My initial wrong deduction was because the initial register used to be $r6 before #182157.

[Saam Barati]

Comment on attachment 332334 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=332334&action=review

>>> Source/JavaScriptCore/ChangeLog:8
>>> +        We still need to keep on saving r6 as it is used by the MacroAssembler
>> 
>> you mean r8, not r6?
> 
> Sorry, I meant that in addition to saving $r8, as the title suggest, we can't stop saving $r6, as I initially wrongly deducted in a first version of the patch that was creating weird crashes :). My initial wrong deduction was because the initial register used to be $r6 before #182157.

Probably worth rewording this to reflect what the patch is actually doing.

[Guillaume Emont]

Created attachment 333719 [details]
Patch

New patch with a more explicit ChangeLog message. Sorry it took me a while to get to it.

[WebKit Commit Bot]

Comment on attachment 333719 [details]
Patch

Clearing flags on attachment: 333719

Committed r228436: <https://trac.webkit.org/changeset/228436>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Radar WebKit Bug Importer]

<rdar://problem/37514115>