RFR: 8161265: [JVMCI] EnableJVMCI should only be required when its not implied by other flags

[Doug Simon]

> On 13 Jul 2016, at 21:36, Doug Simon <doug.simon at oracle.com> wrote:
> 
>> 
>> On 13 Jul 2016, at 20:32, Christian Thalinger <cthalinger at twitter.com> wrote:
>> 
>> 
>> 
>>> On Jul 12, 2016, at 11:20 PM, Doug Simon <doug.simon at oracle.com> wrote:
>>> 
>>> The -XX:+EnableJVMCI option 1) unlocks code paths in the VM related to JVMCI and 2) is required to unlock all other JVMCI options. However, 1 could be achieved by specific JVMCI options without requiring 2. Since JVMCI is experimental, these options already require -XX:+UnlockExperimentalVMOptions. Having to unlock them twice is redundant and makes for unnecessarily long command lines. For example:
>>> 
>>> java -XX:+UnlockExperimentalVMOptions -XX:+EnableJVMCI -XX:+UseJVMCICompiler ...
>>> 
>>> could be:
>>> 
>>> java -XX:+UnlockExperimentalVMOptions -XX:+UseJVMCICompiler ...
>>> 
>>> This webrev removes the need for specifying -XX:+EnableJVMCI for these options:
>>> 
>>> UseJVMCICompiler
>> 
>> Totally makes sense for this one.
>> 
>>> JVMCITraceLevel
>>> JVMCICounterSize
>>> JVMCICountersExcludeCompiler
>>> JVMCIUseFastLocking
>>> JVMCINMethodSizeLimit
>>> TraceUncollectedSpeculations
>> 
>> Not so sure about these.
> 
> Ok, Tom also commented offline that these should still require EnableJVMCI. That is, EnableJVMCI is still explicitly required to enable hosted-only JVMCI compilation. I can see why this makes sense and am preparing another webrev now.

Done - I updated the original webrev.

-Doug