[foreign-memaccess+abi] Integrated: 8255903: Enable multi-register return values for native invokers

[Jorn Vernee]

On Thu, 21 Oct 2021 13:15:39 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

> Hi,
> 
> This patch implements support for multi-register returns in native invokers, and removes the buffered invocation strategy for downcalls. This is achieved, essentially, by using an in memory return: the caller allocates a bit of memory, and the native invoker stub writes the values of the return register to that memory. Then, the post processing code reads the register values back from there.
> 
> Currently, the target address of a downcall is handled separately from the other arguments. I initially implemented passing the IMR address the same way, but I realized the removal of the buffered invocation strategy affords us a better way of doing things: we can just make the target address and the IMR address part of the normal calling sequence, and remove a bunch of special-casing code to handle these. We now just use a binding recipe to unbox these arguments and shuffle them into registers, and the ABIDescriptor tells the native invoker stub which registers to pick up these arguments from.
> 
> Thanks,
> Jorn

This pull request has now been integrated.

Changeset: 818dcfc8
Author:    Jorn Vernee <jvernee at openjdk.org>
URL:       https://git.openjdk.java.net/panama-foreign/commit/818dcfc8e7c0383efb3438a19fc7e24bfdbfcae7
Stats:     1366 lines in 40 files changed: 432 ins; 632 del; 302 mod

8255903: Enable multi-register return values for native invokers

Reviewed-by: mcimadamore

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PR: https://git.openjdk.java.net/panama-foreign/pull/603