RFR: 8329628: Additional changes after JDK-8329332

[Vladimir Kozlov]

On Mon, 8 Apr 2024 07:47:02 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

>> Additional clean up based on comments (mostly Stefan's) during reviews for [JDK-8329332: Remove CompiledMethod and CodeBlobLayout classes](https://bugs.openjdk.org/browse/JDK-8329332).
>> - Renamed `CompiledMethod_lock` to `NMethod_lock`.  (I decided to not change JVMTI's `CompiledMethod[Load|Unload]` names).
>> - Renamed `NMethodIterator::all_blobs` to `NMethodIterator::all`.
>> - Moved `get_deopt_original_pc()` method from `nmethod` to `frame` class.
>> - Reverted `CodeCache::find_nmethod()` to previous functionality to allow return `nullptr` and be consistent with `find_blob()`.
>> - Cleanup some `(nmethod*)` casts.
>> - Use `for (CodeHeap* heap : *_nmethod_heaps) ` in `CodeCache::nmethod_count()` (it was @stefank suggestion,  I don't know how this C++ magic works). I verified it running with `-XX:+PrintNMethodStatistics`.
>> 
>> Testing tier1-3,xcomp,stress
>
> src/hotspot/share/code/codeCache.cpp line 668:
> 
>> 666:   CodeBlob* cb = find_blob(start);
>> 667:   assert(cb == nullptr || cb->is_nmethod(), "did not find an nmethod");
>> 668:   return (nmethod*)cb;
> 
> There's a call to `find_nmethod` in `ZNMethod::load_oop` that now lacks a null-check. Would you mind adding one?

I added asserts in all places where there is no nullptr check.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/18665#discussion_r1556325619