RFR: 8229278: Improve hs_err location printing to assume less about GC internals

[Erik Österlund]

Hi Stefan,

Thank you for the review. I like your cleanups. I folded them in to the 
next webrev: http://cr.openjdk.java.net/~eosterlund/8229278/webrev.01/

/Erik

On 2019-08-27 15:20, Stefan Karlsson wrote:
> Hi Erik,
> 
> On 2019-08-08 11:46, Erik Österlund wrote:
>> Hi,
>>
>> Today when we crash and print hs_err files, the printing utility for 
>> describing heap locations assumes:
>> 1) That the Java heap memory reservation is contiguous
>> 2) That the Java heap is parseable
>> We should let the GC describe a location instead, opting in to such 
>> concepts.
>>
>> This patch adds a print_location pure virtual function on CollectedHeap
>> allowing the GC to choose printing strategy. A new LocationPrinter 
>> utility was added, allowing GCs to implement the functionality easily 
>> without much code duplication.
>>
>> Webrev:
>> http://cr.openjdk.java.net/~eosterlund/8229278/webrev.00/
> 
> This looks good, but I have some cleanups I'd like to make. If you agree 
> we can either fold this into your patch, or I can create a separate RFE 
> for it:
> 
> http://cr.openjdk.java.net/~stefank/8229278/webrev.01.delta/
> 
> 1) Fixed some includes.
> 
> 2) Replaced address with void*. I'd like to no propagate the usage of 
> 'address' into GC code.
> 
> 3) Fixed the usage of is_readable_range to actually include check that 
> the address of the klass field is readable.
> 
> 4) Changed/removed some casts.
> 
> 5) Removed redundant is_in check in ZGC's print_location.
> 
> Thanks,
> StefanK
> 
>>
>> Bug:
>> https://bugs.openjdk.java.net/browse/JDK-8229278
>>
>> Thanks,
>> /Erik