[RFR] Fix clobbered address passed to TSAN

[Arthur Eubanks]

On Wed, Jun 26, 2019 at 6:37 PM Man Cao <manc at google.com> wrote:

> I see the instrumentation for stores (iastore, lastore, ...) is moved from
> pre-barrier to post-barrier. Is that intended?
>
Yes, just to be consistent and lower the risk of clobbered registers there
as well.

>
> A minor issue is that the comment for TSAN in TemplateTable::aaload()
> could be updated.
>
Removed the comment since now it applies to all loads/stores.

>
> If the update is just for the above two issues, no need for another webrev
> and looks good.
>

> However, I'm now a bit skeptical if TSAN read instrumentation in
> TemplateTable::getfield_or_static() are still correct, as they all follow a
> call to access_load_at(), which could invoke GC's read barrier and clobber
> unknown number of registers. Our internal JDK8 TSAN works because there
> were no read barrier in JDK8. Fortunately we at least have the
> verify_oop_index() for checking now.
>
Good point. I'm not sure exactly how `noreg` works, but as you said,
verify_oop_index() isn't complaining.