[webkit-reviews] review granted: [Bug 185231] WebContent crash loading page on seas.upenn.edu @ JavaScriptCore: vmEntryToJavaScript : [Attachment 339423] Patch

[bugzilla-daemon at webkit.org]

Saam Barati <sbarati at apple.com> has granted Michael Saboff
<msaboff at apple.com>'s request for review:
Bug 185231: WebContent crash loading page on seas.upenn.edu @ JavaScriptCore:
vmEntryToJavaScript
https://bugs.webkit.org/show_bug.cgi?id=185231

Attachment 339423: Patch

https://bugs.webkit.org/attachment.cgi?id=339423&action=review




--- Comment #4 from Saam Barati <sbarati at apple.com> ---
Comment on attachment 339423
  --> https://bugs.webkit.org/attachment.cgi?id=339423
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=339423&action=review

r=me

> Source/JavaScriptCore/ChangeLog:10
> +	   We weren't clearing the scratch register cache when switching back
and forth between 
> +	   allowing scratch register usage.  Now we clear when we transition
from disallow to
> +	   allow.

It's worth explaining why this is a problem.

> Source/JavaScriptCore/assembler/AllowMacroScratchRegisterUsageIf.h:45
> +#if CPU(ARM64)
> +	       if (!m_oldValueOfAllowScratchRegister)
> +		   m_masm.invalidateAllTempRegisters();
> +#endif

Shouldn't this invalidation happen on any transition?