Unsafe.{get,put}-X-Unaligned; Efficient array comparison intrinsics (original) (raw)

Andrew Haley aph at redhat.com
Mon Mar 9 09:06:51 UTC 2015

On 08/03/15 23:04, Peter Levart wrote:

On 03/08/2015 12:13 PM, Andrew Haley wrote:

> That's OK if you think this approach is a better division of > concerns (Unsafe being low-level), but in Heap-X-Buffer you are only > using Unsafe.get|putXXXUnaligned() and don't consider using > get|putXXX directly when unalignedAccess() == true. Right, because there's no point in doing so when unalignedAccess() == true because the exact same code will be generated. In my Utopian world nothing except Unsafe would have to deal with issues such as this. However, I think that people writing library code (e.g. array comparison intrinsics) might still need to know. Ah, sorry. I haven't realized that the same code will be generated by compiler intrinsics. So the Java part is just for interpreter and platforms not supporting unaligned access and when UseUnalignedAccesses is explicitly disabled?

That's right. You really have to look at both of these patches, the HotSpot and the JDK part, for this approach to make sense.

Andrew.

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