On 17/05/2018 1:01 PM, Ivan Gerasimov wrote:
On 5/16/18 7:44 PM, David Holmes wrote:
On 17/05/2018 12:30 PM, Ivan Gerasimov wrote:
Hi David!
On 5/16/18 6:12 PM, David Holmes wrote:
Hi Ivan,
Surely you need to back this up with some performance numbers! And
verify not assume that numberOfLeadingZeroes is intrinsified!
Yes, good point.
Please find the benchmark with the results here:
http://cr.openjdk.java.net/~igerasim/8203279/00/MyBenchmark.java
It shows that the new version of HashMap. tableSizeFor() was
(approximately) two times faster.
Impressive. :)
Thanks :)
Of course it's not performance critical code, but why not optimize it by
a tiny bit if possible?
Do you think it's good to go?
I think I'd rather defer to a more performance oriented reviewer -
paging Claes! ;-)
David
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With kind regards,
Ivan
Thanks,
David
With kind regards,
Ivan
Cheers,
David
On 17/05/2018 10:32 AM, Ivan Gerasimov wrote:
Hello!
In a few places we have code that rounds an integer up to the
nearest power of two.
It is done with a series of RSHOTFs and ORs, but it can possibly be
done faster with the use of Integer.numberOfLeadingZeros (assuming
it is intrinsified).
Would you please help review this trivial optimization:
BUGURL: https://bugs.openjdk.java.net/browse/JDK-8203279
WEBREV: http://cr.openjdk.java.net/~igerasim/8203279/00/webrev/
For HashMap.tableSizeFor() I created a simple test with a loop from
Integer.MIN_VALUE to Integer.MAX_VALUE (including), to make sure
the result is the same.
For TimSort.ensureCapacity() I checked all positive values of
minCapacity.
