8254156: Simplify ABI classification logic

[mcimadamore]

This patch reverts recent changes to introduce a public CValueLayout class; the realization here is that, after all, CValueLayout exposes a public Type enum which is used by ABI classification. So, instead of using subclassing (which is messy and tedious with immutable data structures with covariant overrides), let's just double down on layout attributes, get rid of CValueLayout and simply expose the Type enum (now renamed to TypeKind).

---

Progress

• Change must not contain extraneous whitespace
• Change must be properly reviewed

Testing

	Linux x64	Windows x64	macOS x64
Build	✔️ (3/3 passed)	✔️ (2/2 passed)	✔️ (2/2 passed)
Test (tier1)	✔️ (9/9 passed)	⏳ (5/9 running)	✔️ (9/9 passed)

Issue

• JDK-8254156: Simplify ABI classification logic

Reviewers

• Jorn Vernee (@JornVernee - Committer)

Download

$ git fetch https://git.openjdk.java.net/panama-foreign pull/371/head:pull/371
$ git checkout pull/371

[bridgekeeper]

👋 Welcome back mcimadamore! A progress list of the required criteria for merging this PR into foreign-abi will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

@mcimadamore This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8254156: Simplify ABI classification logic

Reviewed-by: jvernee

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been no new commits pushed to the foreign-abi branch. If another commit should be pushed before you perform the /integrate command, your PR will be automatically rebased. If you prefer to avoid any potential automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the foreign-abi branch, type /integrate in a new comment.

[mlbridge]

Webrevs

• 00: Full (198cc71)

[mcimadamore]

/integrate

[openjdk]

@mcimadamore Pushed as commit 6663aab.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

[chrisvest]

Pointer or pointer-sized? We'd also use this one for size_t for instance, right?

[mcimadamore]

This is pointer; e.g. values of this layout will be associated with the MemoryAddress.class carrier. So, no, for size_t, you need something different (either LONG or LONGLONG, depending on the platform). We could probably add a SIZE_T in there, since it's frequent enough.