Adding build-dev@... since this is a build system change.
As for the right HotSpot team, I'm not sure who should be making
the call on changing the way unsafe.cpp is built for macOSX. My guess
when I moved the bug to hotspot/runtime was that someone on the Runtime
team would know, but...
Dan
On 6/3/20 1:38 PM, Vladimir Kempik wrote:
Hello
Can somebody please review this simple change ?
Thanks
6 мая 2020 г., в 12:43, Vladimir Kempik <vkem...@azul.com> написал(а):
Adding hotspot-runtime-dev
23 апр. 2020 г., в 18:26, Vladimir Kempik <vkem...@azul.com> написал(а):
Hello
Please review a fix for JDK-8243470
Long time ago as part of JEP284: New HotSpot Build System this fix was applied
to jdk9 https://bugs.openjdk.java.net/browse/JDK-8152666
At that time it was decided to lower optimisation level for unsafe.cpp from O2
to O1 only for clang on Macosx.
I suppose it was done due to issues in Set/Get<Object> helper functions where
too optimistic optimisations were eliminating some null pointer checks. it was
probably a clang bug.
That issue could be checked with test jdk/test/sun/misc/CopyMemory.java.
I believe that workaround (going from O2 to O1) produced this issue -
https://bugs.openjdk.java.net/browse/JDK-8234963 (Thread.getStackTrace is slow
with clang).
JDK-8234963 can only be seen on mac with libjvm compiled by clang.
Here I propose the patch which eliminates that workaround for clang 8+.
I have tested clang versions 8/9/9.1/10, all of them showed good results:
1) CopyMemory test passes fine on 11/14/15.
2) jdk11/jdk14 passed tck. Regression testing were good as well. jdk15: no new
failures in tck.
3) The testRandom "benchmark" from 8234963 shows great improvements on my
machine, going down from ~200 seconds to ~150 seconds (the newer clang the better
result). For comparision, gcc built libjvm for jdk11 shows ~130 seconds on my machine.
The webrev: http://cr.openjdk.java.net/~vkempik/8243470/webrev.00/
getStackTrace benchmark:
http://cr.openjdk.java.net/~vkempik/8243470/TestRandom.java
The bug: https://bugs.openjdk.java.net/browse/JDK-8243470
Thanks, Vladimir
