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

David Holmes david.holmes at oracle.com
Thu Mar 5 01:01:10 UTC 2015

I'm only glancing at parts of this ...

On 5/03/2015 6:21 AM, Andrew Haley wrote:

John's suggestion works well; the code is smaller and neater.

http://cr.openjdk.java.net/~aph/unaligned.jdk.3/

This doesn't make sense to me:

929 // The byte ordering of this machine 930 public final static boolean LITTLE_ENDIAN = false; 931 public final static boolean BIG_ENDIAN = true;

as they won't necessarily represent "this" machine! And the usage:

! private static final ByteOrder byteOrder ! = unsafe.getByteOrder() == Unsafe.LITTLE_ENDIAN ? ByteOrder.LITTLE_ENDIAN : ByteOrder.BIG_ENDIAN;

suggests getByteorder() is really isBigEndian() (which the hotspot part confirms) - so then the two constants can be removed completely:

private static final ByteOrder byteOrder = unsafe.isBigEndian() ? ByteOrder.BIG_ENDIAN : ByteOrder.LITTLE_ENDIAN;

David

http://cr.openjdk.java.net/~aph/unaligned.hotspot.3/hotspot.patch

Andrew.