RFR: 8259713: Fix comments and ResetNoHandleMark in deoptimization

[Coleen Phillimore]

On Wed, 13 Jan 2021 21:43:40 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

>> This is a small part of the withdrawn change for https://github.com/openjdk/jdk/pull/1990 to fix the out-of-date comments in deoptimization.cpp.
>> Tested with tier1-3.
>
> src/hotspot/share/runtime/deoptimization.cpp line 691:
> 
>> 689:   // do in debug mode to get around the NoHandleMark code in the JRT_LEAF macro
>> 690:   // Beware though because allocating Handles must have a HandleMark or else the
>> 691:   // Handles will be leaked.
> 
> This comment is confusing because there is HandleMark on L693.

My point of this comment is that you should make sure you have a HandleMark if you've used ResetNoHandleMark in JRT_LEAF.

> src/hotspot/share/runtime/deoptimization.cpp line 692:
> 
>> 690:   // Beware though because allocating Handles must have a HandleMark or else the
>> 691:   // Handles will be leaked.
>> 692:   ResetNoHandleMark rnhm;
> 
> So I'm confused. The bug description says:
> 
>> the ResetNoHandleMark is unneeded
> 
> but it is still here.

This one is needed because it's in a JRT_LEAF.  The one above in the JRT_BLOCK_ENTRY is unneeded (along with the comment that matched the one in this unpack_frames() function.)

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PR: https://git.openjdk.java.net/jdk/pull/2069