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

[Johan Sjölen]

On Fri, 27 Jan 2023 10:19:33 GMT, Johan Sjölen <jsjolen 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!

Manual stuff to fix

src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp line 259:

> 257:     }
> 258: 
> 259:     // if (pre_val != null)

nullptr

src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp line 281:

> 279:         __ make_leaf_call(tf, CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_field_pre_entry), "shenandoah_wb_pre", pre_val, tls);
> 280:       } __ end_if();  // (!index)
> 281:     } __ end_if();  // (pre_val != null)

nullptr

src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp line 428:

> 426: 
> 427:       Node* one = __ ConI(1);
> 428:       // is_instof == 0 if base_oop == null

nullptr

src/hotspot/share/gc/shenandoah/shenandoahPhaseTimings.cpp line 61:

> 59:     _worker_data[i] = nullptr;
> 60:     SHENANDOAH_PAR_PHASE_DO(,, SHENANDOAH_WORKER_DATA_nullptr)
> 61: #undef SHENANDOAH_WORKER_DATA_nullptr

Fix these macros

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