RFR: 8160730: [JVMCI] compiler selection should work without -Djvmci.Compiler

[Doug Simon]

> On 06 Jul 2016, at 00:37, Christian Thalinger <cthalinger at twitter.com> wrote:
> 
> 
>> On Jul 2, 2016, at 1:34 PM, Doug Simon <doug.simon at oracle.com> wrote:
>> 
>> Here’s the updated webrev that simplifies auto-selection to only occur when there is exactly one JVMCI compiler available:
>> 
>> http://cr.openjdk.java.net/~dnsimon/8160730.v2/
> 
> Looks better.  Why do you still have the change in src/jdk.vm.ci/share/classes/jdk.vm.ci.hotspot/src/jdk/vm/ci/hotspot/HotSpotJVMCIRuntime.java?

Thanks for the review.

Good point. I’ve reverted that change.

-Doug

>>> On 02 Jul 2016, at 21:01, Doug Simon <doug.simon at oracle.com> wrote:
>>> 
>>> In offline discussion with Tom, we’ve decided that Graal should implement a single JVMCICompilerFactory and use a separate selection mechanism to choose between different compiler configurations. This simplifies the auto-selection mechanism at the JVMCI level to be triggered only if there is a single JVMCI compiler factory available. Unless there’s reasoned objections to this change in direction, I’ll prepare another webrev soon.
>>> 
>>> -Doug
>>> 
>>>> On 02 Jul 2016, at 01:53, Christian Thalinger <cthalinger at twitter.com> wrote:
>>>> 
>>>> 
>>>>> On Jul 1, 2016, at 12:28 PM, Doug Simon <doug.simon at oracle.com> wrote:
>>>>> 
>>>>> Currently, JVMCI compiler selection requires setting the jvmci.Compiler system property. This webrev removes the requirement for explicitly setting the jvmci.Compiler system property if there is only one compiler factory available or if the set of available compiler factories has an inherent selection preference total ordering. It also revives 
>>>>> JvmciNotifyInstallEventTest and modifies it to test that auto-selection of a JVMCI compiler works in the case where there’s exactly one compiler factory available.
>>>>> 
>>>>> 
>>>>> https://bugs.openjdk.java.net/browse/JDK-8160730
>>>>> http://cr.openjdk.java.net/~dnsimon/8160730/
>>>> 
>>>> src/jdk.vm.ci/share/classes/jdk.vm.ci.hotspot/src/jdk/vm/ci/hotspot/HotSpotJVMCICompilerConfig.java
>>>> 
>>>> +         * Compares two compiler factories and returns -1 if {@code o1} should be auto-selected over
>>>> +         * {@code o2}, -1 if {@code o1} should be auto-selected over {@code o2} or 0 if
>>>> The -1 case is documented twice and 1 is not.
>>>> 
>>>> Otherwise this looks good.  I like that change; needing to specify the compiler is annoying.
>>>> 
>>>>> 
>>>>> -Doug
>>>> 
>>> 
>> 
>