RFR: 8203220: Introduce ATTRIBUTE_ALIGNED macro

[Per Liden]

On 05/15/2018 05:07 PM, Thomas Schatzl wrote:
> Hi,
> 
> On Tue, 2018-05-15 at 15:31 +0200, Per Liden wrote:
>> This patch introduces a global ATTRIBUTE_ALIGNED(x) macro, which
>> expands
>> to __attribute__((aligned(x)) or the equivalent of that.
>>
>> We already use this attribute is some parts of the code, but we
>> haven't
>> had a macro in globalDefinitions.hpp for this.
>>
>> In the src/hotspot/cpu/x86/macroAssembler_x86_*.cpp files I chose to
>> keep the ALIGNED_(x) and just define it as ATTRIBUTE_ALIGNED(x),
>> instead of changing all uses of it.
>>
>> Also, for GCC I've included a workaround for a known bug (see the
>> comment in the file). I thought it would be nice to include that
>> since it might otherwise affect quite a few systems.
>>
>> And finally, we don't really have a uniform naming standard for
>> these types of attributes. E.g. we have NOINLINE/ALWAYSINLINE and we
>> have ATTRIBUTE_PRINTF. I chose to use the ATTRIBUTE_ prefix, instead
>> of just ALIGNED, since ALIGNED is somewhat generic and we already
>> have at least one place where a variable is named ALIGNED, so it
>> would conflict.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8203220
>> Webrev: http://cr.openjdk.java.net/~pliden/8203220/webrev.0
> 
>    - it would have been nice to have the ALIGNED_ macro in
> macroAssembler_* replaced by the new ATTRIBUTE_ALIGNED - there are only
> a few uses of it and it does not seem worth to have an extra macro in
> all these places.
> 
> Feel free to ignore, but if you change that I do not need to re-review.

There seem to be ~100 uses of ALIGNED_, but I don't mind changing that.

Inc: http://cr.openjdk.java.net/~pliden/8203220/webrev.0vs1
Full: http://cr.openjdk.java.net/~pliden/8203220/webrev.1

> 
> Looks good.

Thanks for reviewing, Thomas!

/Per

> 
> Thanks,
>    Thomas
>