JDK10/RFR(L): 8144448: Avoid placing CTI immediately following or preceding RDPC instruction.

[Patric Hedlin]

On 2017-06-15 19:51, Vladimir Kozlov wrote:
> Patric,
>
> assembler_sparc.cpp - may be use BytesPerInstWord instead of 4.
Indeed... sloppy me.
>
> In sparc.ad in MachConstantBaseNode::emit() can you use nop() in case 
> disp == 0? To avoid changing O7 reg.
Sure, updated accordingly.

Thanks for your time,
Patric
>
> Thanks,
> Vladimir
>
> On 6/15/17 9:06 AM, Patric Hedlin wrote:
>> Dear all,
>>
>> I would like to ask for help to review the following change/update:
>>
>> Issue:    https://bugs.openjdk.java.net/browse/JDK-8144448
>>
>> Webrev: http://cr.openjdk.java.net/~neliasso/phedlin/tr8144448/
>>
>> Prerequisite: https://bugs.openjdk.java.net/browse/JDK-8181853
>>
>>
>> *** As a comment to the discussion on how to simplify processing of 
>> "mundane" changes,
>>      this change/update comes with an additional prerequisite (patch) 
>> cleaning-up
>>      whitespace and two lingering uses of 'NOT_LP64' and 'LP64_ONLY'.
>>
>> Prerequisite: 
>> http://cr.openjdk.java.net/~neliasso/phedlin/tr8144448.pre/
>>
>>
>> 8144448: Avoid placing CTI immediately following or preceding RDPC 
>> instruction.
>>
>>      Approach taken here is to handle 'rdpc' in the same manner as 
>> 'cbcond', using
>>      a simple scheme to prohibit the assembler from emitting any 
>> 'rdpc' instruction
>>      back-to-back with other CTI ('rdpc' itself included), inserting 
>> 'nop' as needed.
>>
>>
>> Caveat:
>>
>>      This change is applied to all generations of SPARC cores event 
>> though it is the
>>      SPARC Core S5 that is the actual target. Benchmarking on T4 and 
>> M7 suggests that
>>      there is no penalty. This choice (which is subject to change) 
>> has been made in
>>      order to give the update some mileage while waiting for Core S5 
>> hardware to be
>>      available in regular testing.
>>
>>
>> Testing:
>>
>>      Mostly tested on JDK9 (jtreg/RBT/hotspot/tier0-comp).
>>      Testing on JDK10 (jtreg/RBT/hotspot/precheckin-comp).
>>
>>
>> Best regards,
>> Patric