RFR: 8251152: ARM32: jtreg c2 Test8202414 test crash

[Filipp Zhinkin]

Hi Igor,

On Tue, 1 Sep 2020 at 19:46, Igor Ignatyev <igor.ignatyev at oracle.com> wrote:

> Hi Filipp,
>
> 1st of all, welcome back!
>

thanks!


>
> it would be better to throw jtreg.SkippedException at L#46 so jtreg will
> reported the test as skipped (as opposed to just passed).

Thanks, I'll update Test8202414 as well
as compiler/unsafe/JdkInternalMiscUnsafeUnalignedAccess (which also skips
execution the same way).


> alternative, you could use '@requires vm.simpleArch != "arm"' to exclude
> the test from arm32 execution.
>

I was thinking about adding something like vm.unalignedAccess.enabled, but
it seems to be too complicated solution for two tests (Test8202414
and compiler/unsafe/JdkInternalMiscUnsafeUnalignedAccess).
I don't want to use 'simpleArch', because if some new platform missing
unaligned access support will be added in the future then someone will have
to spend time to find out why a test crashes.

Thanks,
Filipp.


>
> Thanks,
> -- Igor
>
>
> > On Sep 1, 2020, at 8:29 AM, Filipp Zhinkin <filipp.zhinkin at gmail.com>
> wrote:
> >
> > Hi,
> >
> > Test8202414 crashes on ARM32 while writing to memory using an unaligned
> > address.
> > ARM32 supports unaligned memory accesses for some load/store instructions
> > under certain conditions, but LDRD (which is used when we're calling
> > Unsafe::putLong) is always causing alignment fault when called with an
> > unaligned address [1].
> >
> > The fix is simply skipping the test execution if a platform does not
> > support unaligned memory accesses.
> >
> > Bug: https://bugs.openjdk.java.net/browse/JDK-8251152
> > Webrev:
> http://cr.openjdk.java.net/~bulasevich/fzhinkin/8251152/webrev.0/
> >
> > [1] ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition,
> §A3.2.1
> > Unaligned data access https://developer.arm.com/documentation/ddi0406/cd
> >
> > Thanks,
> > Filipp.
>
>