RFR: JDK-8301225: Replace NULL with nullptr in share/gc/shenandoah/

[Johan Sjölen]

On Fri, 27 Jan 2023 17:11:40 GMT, Kelvin Nilsen <kdnilsen at openjdk.org> wrote:

>> Hi, this PR changes all occurrences of NULL to nullptr for the subdirectory share/gc/shenandoah/. Unfortunately the script that does the change isn't perfect, and so we
>> need to comb through these manually to make sure nothing has gone wrong. I also review these changes but things slip past my eyes sometimes.
>> 
>> Here are some typical things to look out for:
>> 
>> 1. No changes but copyright header changed (probably because I reverted some changes but forgot the copyright).
>> 2. Macros having their NULL changed to nullptr, these are added to the script when I find them. They should be NULL.
>> 3. nullptr in comments and logs. We try to use lower case "null" in these cases as it reads better. An exception is made when code expressions are in a comment.
>> 
>> An example of this:
>> 
>> ```c++
>> // This function returns null
>> void* ret_null();
>> // This function returns true if *x == nullptr
>> bool is_nullptr(void** x);
>> 
>> 
>> Note how `nullptr` participates in a code expression here, we really are talking about the specific value `nullptr`.
>> 
>> Thanks!
>
> src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp line 2:
> 
>> 1: /*
>> 2:  * Copyright (c) 2023, 2023, Oracle and/or its affiliates. All rights reserved.
> 
> minor glitch here

Weird, first time I'm seeing this glitch. Thanks!

> src/hotspot/share/gc/shenandoah/shenandoahMarkBitMap.hpp line 2:
> 
>> 1: /*
>> 2:  * Copyright (c) 2018, 2023, Oracle and/or its affiliates. All rights reserved.
> 
> Probably should be 2018, 2019, 2023

This and the other ones are correct, it's `$FirstChange, $LastChange, `

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PR: https://git.openjdk.org/jdk/pull/12251