RFR: 8263017: Read barriers are missing in nmethod printing code [v2]

[Erik Österlund]

On Fri, 12 Mar 2021 11:25:26 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> OOP accesses from nmethod printing code miss read barriers. 
>> It causes sporadic crashes when the code stumbles upon a stale OOP.
>> 
>> When `nmethod::print_nmethod` is invoked, the corresponding nmethod is already installed in the code cache and there was a safepoint check in between (see `ThreadToNativeFromVM` usage in `CompileBroker::invoke_compiler_on_method`).
>>  
>> The fix adds missing read barriers in `oop_Relocation::oop_value()` and introduces `oop_Relocation::raw_oop_value()` for cases when read barriers aren't needed.
>> 
>> Along the way, there are some cleanups applied (e.g, `nmethod::print_[oops|metadata]` is superseded by `nmethod::print_recorded_[oops|metadata]`).
>> 
>> Testing:
>> - [x] failing test w/ `-XX:+UseZGC` `-XX:ZCollectionInterval=0.01` `-XX:ZFragmentationLimit=0`
>> - [x] hs-tier1 - hs-tier4
>> 
>> Thanks!
>
> Vladimir Ivanov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Use CompiledMethod::run_nmethod_entry_barrier()

Looks good.

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Marked as reviewed by eosterlund (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/2919