[aarch64-port-dev ] aarch64: Fix a bug in TestOptionsWithRanges of hotspot

[Yang Zhang]

I have modified the patch according your comments. I am testing the new patch.
When it's okay, I will send it again.

Regards
Yang

On 28 June 2016 at 18:09, Stuart Monteith <stuart.monteith at linaro.org> wrote:
> From my reading of this - BlockZeroingLowLimit is the N bytes that dc zva
> would write in a single operation - zva_length.
> I can see a case for the minimum of being zva_length, but the maximum
> shouldn't have a limit really - and nothing as small as you are suggesting.
> That the cmp immediate limit is smaller than we like is incidental to the
> actual limit we'd be aiming for. Say, for example, there was only an
> advantage on some machines/workloads above 2 MB.
>
> Can you look into reworking the "cmp" call to something more permissive?
>
> Thanks,
>
>    Stuart
>
>
> On 28 June 2016 at 09:40, Yang Zhang <yang.zhang at linaro.org> wrote:
>>
>> In file src/cpu/aarch64/vm/stubGenerator_aarch64.cpp:2350,
>> BlockZeroingLowLimit is used as follows:
>> __ cmp(cnt_words, BlockZeroingLowLimit >> 3);
>>
>> On aarch64 platform, the immediate in cmp instruction has 12
>> significant bits which could be 0xXXX or 0xXXX000. The immediate is
>> calculated by BlockZeroingLowLimit >> 3. So BlockZeroingLowLimit has
>> 15 significant bits. It's low limit, and a vary large value isn't
>> meaningful. So the range of BlockZeroingLowLimit should be [1, 2^15 -
>> 1].
>>
>> On 28 June 2016 at 16:16, Andrew Haley <aph at redhat.com> wrote:
>> > On 28/06/16 05:09, Yang Zhang wrote:
>> >> Could someone please help to review and process attached patch for
>> >> fixing
>> >> an issue about BlockZeroingLowLimit in hotspot openjdk9 aarch64?
>> >>
>> >> This issue is exposed by a test failure in hotspot jtreg openjdk9 for
>> >> aarch64
>> >>
>> >> runtime/CommandLine/OptionsValidation/TestOptionsWithRanges.java
>> >>
>> >> It is caused by improper range of BlockZeroingLowLimit.
>> >
>> > Surely this is just papering over the real bug.
>> >
>> > Andrew.
>> >
>
>