RFR: 8333658: NMT: Use an allocator with 4-byte pointers to save memory in NativeCallStackStorage [v21]

[Johan Sjölen]

On Thu, 20 Jun 2024 05:53:08 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>One thing I don't understand. I thought the point of this new class is to move the stacks over to the new allocator-with-freelist, and make StackIndex a simple typedef for the allocator index? Then, get rid of the GrowableArray?
>You put the hashtable entries in there, which is okay, but not using the full potential of this new class.

No, the initial point was to get rid of pointer-heavy structure's unnecessarily large pointers. The discussion of StackIndex and its wrapping came later in the review process. Moving the `StackIndex` to a simple typedef is its own RFE. If I were to use `HOA` for the stacks in this PR, then I wouldn't do the refactoring of `StackIndex` into a typedef :-).

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PR Comment: https://git.openjdk.org/jdk/pull/18979#issuecomment-2180149420