RFR(M): 8194490: [JVMCI] Move `iterateFrames` to C++

[Vladimir Kozlov]

Hi Gilles,

What happened to this fix?

Testing all passed but it was not pushed.

Thanks,
Vladimir

On 2/1/18 5:21 PM, Vladimir Kozlov wrote:
> Thank you, Gilles
> 
> Seems fine to me. Who reviewed it in Labs?
> 
> And thank you for running testing.
> 
> Vladimir
> 
> On 1/22/18 6:58 AM, Gilles Duboscq wrote:
>> Hi,
>>
>> Please review the following fix for `HotSpotStackIntrospection.iterateFrames`.
>> It moves the iteration code from Java to C++: this helps with an issue that would arise if the 
>> nmethod containing the `iterateFrames` hits and uncommon trap during iteration. IT would change 
>> the layout of the top frames which would confuse the stack walking logic. Having this loop in C++ 
>> ensure there can be no uncommon trap.
>>
>> Webrev: http://cr.openjdk.java.net/~gdub/webrev-8194490/
>> Issue: https://bugs.openjdk.java.net/browse/JDK-8194490
>> Testing: hs-tier1,hs-tier2,hs-precheckin-comp
>>
>> It's bit unfortunate that we have tests for implementation details of JVMCI (i.e., tests for 
>> CompilerToVM) instead of tests for the actual API.
>>
>> Thanks,
>>   Gilles
>>