[9] RFR (S) 8147978: Remove Method::_method_data for C1

David Holmes david.holmes at oracle.com
Thu Feb 25 07:46:17 UTC 2016

On 25/02/2016 10:57 AM, Chris Plummer wrote:
> Hello,
> I still need to finish up review of this change. I added the change that
> David suggested. Since it's minor, I'll just post the code from
> arguments.cpp here:
> #if !defined(COMPILER2) && !INCLUDE_JVMCI
>    UNSUPPORTED_OPTION(ProfileInterpreter, "ProfileInterpreter");
>    UNSUPPORTED_OPTION(TraceProfileInterpreter, "TraceProfileInterpreter");
>    UNSUPPORTED_OPTION(PrintMethodData, "PrintMethodData");
> #endif
> The ProfileInterpreter related code was in the original code review. The
> other two flag checks I just added.

That addition seems fine to me. But I'll leave it to the compiler folk 
to review the core changes.


> thanks,
> Chris
> On 2/4/16 6:10 PM, Chris Plummer wrote:
>> Hi David,
>> On 2/4/16 5:43 PM, David Holmes wrote:
>>> Hi Chris,
>>> On 4/02/2016 5:20 PM, Chris Plummer wrote:
>>>> Hello,
>>>> Please review the following for removing Method::_method_data when only
>>>> supporting C1 (or more specifically, when not supporting C2 or JVMCI).
>>> Does JVMCI exist with C1 only?
>> My understanding is it can exists with C2 or on its own, but currently
>> is not included with C1 builds.
>>> The COMPILER2_OR_JVMCI conjunction makes things a bit messy. Can we
>>> abstract that behind a single variable, INCLUDE_METHOD_DATA (or some
>>> such) to make it cleaner?
>> I'll also be using COMPILER2_OR_JVMCI with another change to that
>> removes some MethodCounter fields. So yes, I can add
>> INCLUDE_METHOD_DATA, but then will need another INCLUDE_XXX for the
>> MethodCounter fields I'll be conditionally removing.
>>>> This will help reduce dynamic footprint usage for the minimal VM.
>>>> As part of this fix, ProfileInterperter is forced to false unless C2 or
>>>> JVMCI is supported. This was mainly done to avoid crashes if it is
>>>> turned on and Method::_method_data has been excluded, but also because
>>>> it is not useful except to C2 or JVMCI.
>>> Are you saying that the information generated by ProfileInterpreter
>>> is only used by C2 and JVMCI? If that is case it should really have
>>> been a C2 only flag.
>> That is my understanding. Coleen confirmed it for me. I believe she
>> got her info from the compiler team. BTW, we need a mechanism to make
>> these conditionally unsupported flags a constant value when they are
>> not supported. It would help deadstrip code.
>>> If ProfileInterpreter is forced to false then shouldn't you also be
>>> checking TraceProfileInterpreter and PrintMethodData use as well
>> Yes, I can add those.
>> thanks,
>> Chris
>>> Thanks,
>>> David
>>>> Webrev: http://cr.openjdk.java.net/~cjplummer/8147978/webrev.02/
>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8147978
>>>> Test with JPRT -testset hotspot.
>>>> thanks,
>>>> Chris

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