[aarch64-port-dev ] RFR: 8187472 - AARCH64: array_equals intrinsic doesn't use prefetch for large arrays

Andrew Haley aph at redhat.com
Fri Feb 9 09:19:16 UTC 2018

On 08/02/18 09:54, Andrew Haley wrote:
>    b(SAME);
> This pessimizes a very common case of string comparisons, those of
> about 32 bytes.  Please think again.

I have a suggestion:

You could run an instrumented version of OpenJDK on couple of apps
which use a lot of strings.  (I suggest the javac invocation in the
OpenJKD build which builds java.base and SPECjbb.)  This instrumented
version should record the lengths of the strings which are compared
and the first character where they differ.  Then use the result to
determine what to optimize for.

Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
EAC8 43EB D3EF DB98 CC77 2FAD A5CD 6035 332F A671

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