RFR(S) : 8238049 : TieredCompilation shouldn't be re-enabled if CompilationMode is high-only

[Igor Veresov]

Setting CompilationMode actually requires tiered to be on in order to be meaningful. It's a mode of tiered compilation. The ultimate goal is to remove the old compilation policies, so long term, assume that tiered is always on.
It seems to me that the command line you quoted is actually working as intended. Does it cause any problems?


igor



> On Jan 28, 2020, at 2:52 PM, Igor Ignatyev <igor.ignatyev at oracle.com> wrote:
> 
> http://cr.openjdk.java.net/~iignatyev/8238049/webrev.00/
>> 9 lines changed: 3 ins; 2 del; 4 mod;
> 
> 
> Hi all,
> 
> could you please review the small and trivial-ish patch?
> from JBS:
>> currently, if you run java w/ -XX:-TieredCompilation -XX:+UseJVMCICompiler, TieredCompilation will be set back to true and change CompilationMode from "default" to "high-only-quick-internal" (w/o actually changing the value of the flag though). if you run it w/ '-XX:-TieredCompilation -XX:+UseJVMCICompile -XX:CompilationMode=high-only', TieredCompilation will be changed to true, but CompilationMode will remain high-only, so effectively it just needlessly enables TieredCompilation.
> 
> the patch not only leaves TieredCompilation disabled when CompilationMode is high-only, but also changes the actual value of CompilationMode flag, so it will be properly reported.
> 
> JBS: https://bugs.openjdk.java.net/browse/JDK-8238049
> webrev: http://cr.openjdk.java.net/~iignatyev/8238049/webrev.00/
> testing: manual by java -XX:+PrintFlagsFinal w/ {-TieredCompilation,+TieredCompilation}x{CompilationMode=default,CompilationMode=high-only,""}
> 
> Thanks,
> -- Igor