Unsafe.{get,put}-X-Unaligned performance

[Peter Levart]

On 03/11/2015 06:27 PM, Andrew Haley wrote:
> On 03/11/2015 07:10 AM, John Rose wrote:
>>> John: I'm waiting for an answer to my question here before I submit
>>> a webrev for approval.
>>>
>>> http://mail.openjdk.java.net/pipermail/panama-dev/2015-March/000099.html
>> (Answered.)
> http://cr.openjdk.java.net/~aph/unaligned.jdk.5/
> http://cr.openjdk.java.net/~aph/unaligned.hotspot.5/
>
> I hope everybody is happy with this, or at least not so unhappy that
> they would want to reject it altogether.
>
> There is no bug ID for this yet.  John, would you like to create a bug
> database entry?  If not, I'll do so.  Then I can go for a RFR, which
> hopefully should be a shoo-in now that we've beaten this thing to
> death.  :-)
>
> Andrew.

Hi Andrew,

Just an observation. In Heap-X-Buffer.java.template, you are using 
self-sufficient form of methods for integral types:

  377     public int getInt() {
  378         return unsafe.getIntUnaligned(hb, 
byteOffset(nextGetIndex(4)), bigEndian);
  379     }
  380
  381     public int getInt(int i) {
  382         return unsafe.getIntUnaligned(hb, byteOffset(checkIndex(i, 
4)), bigEndian);
  383     }

...but for floating point, you use:

  479     public float getFloat() {
  480         return getFloat(nextGetIndex(4));
  481     }
  482
  483     public float getFloat(int i) {
  484         int x = unsafe.getIntUnaligned(hb, 
byteOffset(checkIndex(i, 4)), bigEndian);
  485         return Float.intBitsToFloat(x);
  486     }

...getFloat() is calling getFloat(int) which is a virtual method with 2 
implementations. I think it would be better to in-line the the call and 
eliminate the need to execute checkIndex()...


Regards, Peter

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