RFR (S) 8184753: Asserts against MinObjectAlignment should avoid integer division

[Aleksey Shipilev]

On 07/18/2017 10:02 AM, Aleksey Shipilev wrote:
> On 07/18/2017 09:58 AM, Mikael Gerdin wrote:
>> Hi Aleksey,
>>
>> On 2017-07-18 09:51, Aleksey Shipilev wrote:
>>> Hi Mikael,
>>>
>>> On 07/18/2017 09:48 AM, Mikael Gerdin wrote:
>>>>> Noticed two new asserts in arguments.cpp have excess whitespace, fixed:
>>>>>     http://cr.openjdk.java.net/~shade/8184753/webrev.02
>>>>
>>>> Did you consider using is_object_aligned in the newly created align.hpp?
>>>>
>>>> http://hg.openjdk.java.net/jdk10/hs/hotspot/file/5e9c41536bd2/src/share/vm/utilities/align.hpp#l120
>>>>
>>>>
>>>> inline bool is_object_aligned(size_t word_size) {
>>>>    return is_aligned(word_size, MinObjAlignment);
>>>> }
>>>
>>> I did, but haven't done this for two reasons:
>>>    a) The asserts are about object _sizes_, not the objects themselves;
>>>    b) Doing *Mask fits other uses of MinObjAlignment(InBytes)(Mask) around HS;
>>
>>
>> But the is_object_aligned(size_t) function _is_ about object sizes, it just has
>> a weird naming and a weird overload with the void* variant which asserts that a
>> pointer is correctly aligned.
> 
> Ah, unfortunate naming indeed. Let me try to switch to is_object_aligned.

That seems to work well:
  http://cr.openjdk.java.net/~shade/8184753/webrev.03/
  http://cr.openjdk.java.net/~shade/8184753/hotspot.changeset

hotspot_tier1 seems fine.

NB: Changed the synopsis for the change.

Thanks,
-Aleksey