RFR JDK-8141491: Unaligned memory access in Bits.c

Mikael Vidstedt mikael.vidstedt at oracle.com
Wed Nov 25 21:32:37 UTC 2015

Have you looked anything at the performance of the generated code? As 
you may have seen I was playing around with an alternative 
implementation[1] which has the benefit of being pure C++ without 
compiler specific hints. That said, when I did some initial benchmarking 
of that it did seem like the performance impact was significant. I 
didn't have time to look at more in detail why, and will not have time 
to return to that until late next week earliest. It would be interesting 
to understand what type of performance you see with your patch.



On 2015-11-25 11:42, Coleen Phillimore wrote:
> Sending to core-libs mailing list.
> On 11/25/15 2:19 PM, Alexander Smundak wrote:
>> Please take a look at
>> http://cr.openjdk.java.net/~asmundak/8141491/jdk/webrev.00
>> that fixes the problem.
>> It utilizes the ability of some (GCC and Clang) to declare data
>> alignment explicitly.
>> I have verified it works on x86_64 Linux by running
>> jdk/test/java/nio/Buffer/Basic.java test
>> I need a sponsor.
>> Sasha

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