RFR(XS): 8149973: Optimize object alignment check in debug builds.

[David Holmes]

On 3/03/2016 2:03 AM, Dmitry Dmitriev wrote:
> Hello Coleen,
>
> I implement refactoring which removes repeating of '&' expression.
> In g1OopClosures.inline.hpp and g1RemSet.inline.hpp I removed extracting
> of oopDesc* from oop and added call to check_obj_alignment instead.
> Updated webrev.01:
> http://cr.openjdk.java.net/~ddmitriev/8149973/webrev.01/
> <http://cr.openjdk.java.net/%7Eddmitriev/8149973/webrev.01/>
> Testing: jprt, hotspot_all & vm.quick(still in progress, no new failures).

I'm unclear on how the CHECK_UNHANDLED_OOPS case is handled in the 
cast_from_oop. In the original we had to "unwrap" obj as obj.obj(), but 
that no longer appears anywhere. ??

Thanks,
David

> Thanks,
> Dmitry
>
>
> On 24.02.2016 15:35, Coleen Phillimore wrote:
>>
>> From
>> http://cr.openjdk.java.net/~ddmitriev/8149973/webrev.00/src/share/vm/gc/g1/g1OopClosures.inline.hpp.udiff.html
>>
>> http://cr.openjdk.java.net/~ddmitriev/8149973/webrev.00/src/share/vm/gc/g1/g1RemSet.inline.hpp.udiff.html
>>
>>
>> Can you just call
>>
>>    assert(check_obj_alignment(o), "not oop aligned");
>>
>> rather than repeating the & expression?   The check_obj_alignment is
>> inlined.
>>
>> Coleen
>>
>> On 2/24/16 5:42 AM, Dmitry Dmitriev wrote:
>>> Hello,
>>>
>>> Please, review small optimization to the object alignment check in
>>> the debug builds. In this fix I replace division by
>>> MinObjAlignmentInBytes to bitwise AND operation with
>>> MinObjAlignmentInBytesMask, because MinObjAlignmentInBytes is a power
>>> of two. Suggested construction already used in MacroAssembler, e.g.
>>> hotspot/src/cpu/x86/vm/c1_MacroAssembler_x86.cpp).
>>>
>>> JBS: https://bugs.openjdk.java.net/browse/JDK-8149973
>>> webrev.00: http://cr.openjdk.java.net/~ddmitriev/8149973/webrev.00/
>>> <http://cr.openjdk.java.net/%7Eddmitriev/8149973/webrev.00/>
>>> Testing: jprt, hotspot_all
>>>
>>> Thanks,
>>> Dmitry
>>
>