From Jim's bug report:
"Mac OS X should use -O3 optimization level to be consistent with other
platforms and benefit Mac OS X java with the same performance levels as
other platforms.
Mac OS X has used -Os level optimization since management of the
platform JDK was handed over from Apple. This level of optimization was
Apple's policy, not OpenJDK's. The policy was established in a time when
memory was tight (I was there at the time.) Since then other platforms
have moved on, making the decision to target speed over disk space.
Specifically, using -O3 level optimization.
I've personally seen 20-30% improvement in performance in C/C++
applications using -O3 over -Os. But, of course, the performance team
should verify the affect on the JDK.
A 11% real time improvement can be seen with a rough HelloWord compile/run."
I discussed this with Claes, our performance guru, and he agreed that it
is low risk enough that we can push this for JDK 15.
Bug: https://bugs.openjdk.java.net/browse/JDK-8246751
WebRev:
http://cr.openjdk.java.net/~ihse/JDK-8246751-macos-optimize-O3/webrev.01
/Magnus
