[foreign-memaccess+abi] RFR: 8274912: Eagerly generate native invokers [v2]

[Jorn Vernee]

> Hi,
> 
> This patch is a refactoring of VM code pertaining to downcalls. As outlined in the JBS issue, this patch makes 'native invoker' generation currently done by C2 eager.
> 
> Most of the changes in this patch are moving around existing code:
> - The native invoker generation code is moved from sharedRuntime*.cpp to universalNativeInvoker*.cpp, to match what is done for upcalls.
> - C2 & nmethod scaffolding for registering native invokers has been removed (lifetime is now managed in Java code).
> - Now, C2 will only intrinsify trivial downcalls, which means some of the code was simplified there.
> - To reduce code duplication, several utilities have been added:
>   - ArgumentShuffle (and impls of CallConvClosure): a utility class for computing argument shuffles and generating shuffling code. The shuffling code is heavily based on what is done today for optimized upcalls on x64.
>   - To support the above, I've made a copy of the ComputeMoveOrder utility from SharedRuntime code (which was only implemented on x64), and adapted it to our use case.
>   - RegSpillFill: similarly, a utility for computing and generating register spill and fill code (given a list of registers).
>   - oop_cast: this was a pre-existing utility that was renamed (from 'cast') and moved into a separate file.
> - The linkToNative method handle stub now just loads the invoker address from the appendix argument and jumps to it, instead of jumping to the fallback method handle.
> 
> The implementation passes all the jdk_foreign tests on Windows/x64, Linux/x64 (WSL), and Linux/AArch64. Though, there were some pre-exsiting test failures on AArch64 wrt variadic functions.
> 
> Thanks,
> Jorn

Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:

  AArch64 comments

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Changes:
  - all: https://git.openjdk.java.net/panama-foreign/pull/593/files
  - new: https://git.openjdk.java.net/panama-foreign/pull/593/files/493165e4..febe2ffc

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=593&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=593&range=00-01

  Stats: 43 lines in 3 files changed: 0 ins; 0 del; 43 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/593.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/593/head:pull/593

PR: https://git.openjdk.java.net/panama-foreign/pull/593