RFR: 8198571: [JVMCI] must not install wide vector code unless runtime supports it

[Doug Simon]

Thanks Vladimir.

Can I get another review please?

-Doug

> On 23 Feb 2018, at 21:14, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:
> 
> Okay. Then it is good.
> 
> Thanks,
> Vladimir
> 
> On 2/23/18 11:59 AM, Doug Simon wrote:
>> Yes. We have a separate fix for Graal that does what you propose. This is just a last bit of defense to prevent a VM crash in case the bug creeps back into Graal (or any other JVMCI compiler).
>> Sent from my iPhone
>>> On 23 Feb 2018, at 8:54 pm, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:
>>> 
>>> Hi Doug,
>>> 
>>> Are you planning changes to check MaxVectorSize value when vectors are generated by Graal?
>>> Throwing exception during code installation is very late and expensive (you have to throw out all methods with vectors after spending CPUs to compile them).
>>> 
>>> Thanks,
>>> Vladimir
>>> 
>>>> On 2/23/18 8:57 AM, Doug Simon wrote:
>>>> As shown in https://github.com/oracle/graal/issues/303, a bug in a JVMCI compiler can result in vector code being installed even if the runtime doesn't support it. JVMCI should be defensive and raise an exception in this case.
>>>> https://bugs.openjdk.java.net/browse/JDK-8198571
>>>> http://cr.openjdk.java.net/~dnsimon/8198571/
>>>> -Doug