[webkit-reviews] review denied: [Bug 124447] Crash in virtualForThunkGenerator generated code on ARM64 : [Attachment 217115] Patch

[bugzilla-daemon at webkit.org]

Geoffrey Garen <ggaren at apple.com> has denied Michael Saboff
<msaboff at apple.com>'s request for review:
Bug 124447: Crash in virtualForThunkGenerator generated code on ARM64
https://bugs.webkit.org/show_bug.cgi?id=124447

Attachment 217115: Patch
https://bugs.webkit.org/attachment.cgi?id=217115&action=review

------- Additional Comments from Geoffrey Garen <ggaren at apple.com>
View in context: https://bugs.webkit.org/attachment.cgi?id=217115&action=review


r- since we still appear to be crashing in function call code.

> Source/JavaScriptCore/ChangeLog:11
> +	   Changed nonArgGPR0, nonArgGPR1 and nonArgGPR2 for X86 and X86_64 to
not match up with
> +	   regT0-2.  Changing these registers will cause a crash on all ports
should we have a
> +	   similar problem in the future.  Changed the DFG call generating code
to use regT0 and
> +	   regT1.  Added r12 to X86_64 as a new temp register (regT9) and moved
r13 down to regT10.

This says a lot about what you did, but not much about why.

For example, you didn't mention that x86_64 overlaps regT0 and nonArgGPR0, but
ARM does not, which is why this crash only happens on ARM. You didn't explain
why you added r12 (to facilitate non-overlapping registers on x86_64). You also
didn't explain why you made the change to regT0/regT1.