Integrated: 8315801: [PPC64] JNI code should be more similar to the Panama implementation

[Martin Doerr]

On Wed, 6 Sep 2023 15:57:24 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

> This PR removes writing parameters to stack which are passed in registers. (See JBS issue for more details.) This allows us to get rid of the extra parameter for `c_calling_convention`.
> 
> We can also remove the extra space for the Parameter Save Area in some ABIv2 cases (ppc64le). Note that JNI and runtime calls don't support VarArgs (except as array object for JNI), so this optimization is valid (unlike in downcalls for Panama).
> 
> The offset of floats on stack can be put into a constant and used by interpreter and `c_calling_convention`. Panama handles this in the CallArranger. Added comment which resolves a Panama "todo".
> 
> Tests have passed on linux ppc64 and ppc64le and AIX.

This pull request has now been integrated.

Changeset: 368e4f60
Author:    Martin Doerr <mdoerr at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/368e4f60a937f5cf6919c1dd41fc791b1f7bf205
Stats:     157 lines in 14 files changed: 17 ins; 104 del; 36 mod

8315801: [PPC64] JNI code should be more similar to the Panama implementation

Reviewed-by: rrich, lucy

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PR: https://git.openjdk.org/jdk/pull/15599