RFR(xs): 8205578: jtreg: Fix failing TestRTMAbortRatio on PPC64

[Gustavo Romero]

Hi,

Could the following simple change be reviewed please?

bug   : https://bugs.openjdk.java.net/browse/JDK-8205578
webrev: http://cr.openjdk.java.net/~gromero/8205578/v1/

Currently native method pageSize() is used to cause deliberate transactional
aborts. However in test TestRTMAbortRatio pageSize() is not marked to be
compilable and as a consequence it's never called through the code path of
SharedRuntime::generate_native_wrapper(). As that code path is never exercised
no 'tabort' on JNI call is executed and the test fails on Power because of fewer
aborts than expected by the test.

I can't say for sure why that test is getting the correct number of aborts on
x86. Nonetheless I can confirm that even on x86 the aborts do not come from the
native wrapper, i.e. from 'xabort' in SharedRuntime::generate_native_wrapper().
I suspect the aborts on x86 are occurring a bit latter when the native function
is called and a "Far Call" is executed in the native method by chance and not in
a controlled way. As far as I know there is no way to inspect the exact address
when a transaction failed on Intel as it's possible on Power.

Anyway, marking pageSize() as compilable does not cause any regression on Intel
(at the same time it starts to exercise the generate_native_wrapper code path)
and makes the test pass on Power as expected.

So it fixes the following test on Power:

+Passed: compiler/rtm/locking/TestRTMAbortRatio.java


Thank you and best regards,
Gustavo