RFR: 8322476: Remove GrowableArray C-Heap version, replace usages with GrowableArrayCHeap

[Johan Sjölen]

On Thu, 21 Dec 2023 10:48:30 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> [JDK-8247755](https://bugs.openjdk.org/browse/JDK-8247755) introduced the `GrowableArrayCHeap`. This duplicates the current C-Heap allocation capability in `GrowableArray`. I now remove that from `GrowableArray` and move all usages to `GrowableArrayCHeap`.
>> 
>> This has a few advantages:
>> - Clear separation between arena (and resource area) allocating array and C-heap allocating array.
>> - We can prevent assigning / copying between arrays of different allocation strategies already at compile time, and not only with asserts at runtime.
>> - We should not have multiple implementations of the same thing (C-Heap backed array).
>> - `GrowableArrayCHeap` is NONCOPYABLE. This is a nice restriction, we now know that C-Heap backed arrays do not get copied unknowingly.
>> 
>> **Bonus**
>> We can now restrict `GrowableArray` element type `E` to be `std::is_trivially_destructible<E>::value == true`. The idea is that arena / resource allocated arrays get abandoned, often without being even cleared. Hence, the elements in the array are never destructed. But if we only use elements that are trivially destructible, then it makes no difference if the destructors are ever called, or the elements simply abandoned.
>> 
>> For `GrowableArrayCHeap`, we expect that the user eventually calls the destructor for the array, which in turn calls the destructors of the remaining elements. Hence, it is up to the user to ensure the cleanup. And so we can allow non-trivial destructors.
>> 
>> **Testing**
>> Tier1-3 + stress testing: pending
>
> src/hotspot/share/utilities/growableArray.hpp line 621:
> 
>> 619: //  - Arena
>> 620: //
>> 621: // Itself, it can be embedded, on stack, resource_arena or arena allocated.
> 
> "Itself can be allocated on stack, resource area or arena allocated."

That it can be embedded into another class/struct is a given, imho.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17160#discussion_r1433904533