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

[Gilles Duboscq]

Hi Vladimir,

Sorry about that, somehow i never saw your first message.
Tom and Doug reviewed the JDK8 version internally.

Beside the copyright year change of `src/hotspot/share/jvmci/jvmciCompilerToVM.cpp` everything still applies cleanly.
Should i consider this reviewed?
I guess i should re-run the tests since it's been a while.

 Gilles

On 01/03/18 23:58, Vladimir Kozlov wrote:
> 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
>>>