[RFR] Fix clobbered address passed to TSAN

[Jean Christophe Beyler]

Hi Arthur,

LGTM,  I was curious if the DEBUG code you added made sense to go upstream
to help diagnose issues or was this a failure that is only provoked by
TSAN's instrumentation before this patch and can never happen otherwise?

Thanks,
Jc

On Wed, Jun 26, 2019 at 8:47 AM Arthur Eubanks <aeubanks at google.com> wrote:

> webrev:
> http://cr.openjdk.java.net/~aeubanks/tsanarrayclobber/webrev.00/index.html
> (ignore the wrong description, webrev.ksh is weird, it's good locally)
>
> Fix clobbered address passed to TSAN
>
> access_load_at() sometimes clobbered the address we passed to TSAN in
> tsan_observe_load_or_store().
>
> Do the TSAN instrumentation first, then do the load. Initially the order
> was access_load_at(), then TSAN instrumentation. Field accesses can behave
> as volatile, and I wanted arrays to match up wi
> th the field TSAN instrumentation/actual load order. But it doesn't really
> matter for array loads since they can never be volatile.
> Added some asserts for fastdebug that the oop is valid and that the
> field/element offset is within the oop size. The size check fails without
> the TSAN instrumentation/actual load reordering becau
> se the offset register was clobbered.
>


-- 

Thanks,
Jc