[foreign-memaccess+abi] RFR: 8275332: Variadic functions don't work on Linux/AArch64

[Andrew Haley]

On Tue, 19 Oct 2021 08:54:24 GMT, Nick Gasson <ngasson at openjdk.org> wrote:

> Variable length argument lists are handled differently in the
> Mac/Windows and Linux ABIs on AArch64.  Following the recent API refresh
> on the foreign-memaccess+abi branch the Mac behaviour was inadvertently
> applied on Linux too.  This patch restores the correct behaviour on
> Linux and adds a CallArranger unit test so regressions can be more
> easily caught.
> 
> I just added an extra varArgsOnStack argument to
> CallArranger.getBindings() as that seemed the simplest fix, although it
> could get unwieldy if there were too many configurable options.

The way the boolean `varArgsOnStack` is used here, being passed through multiple calls, is kinda awful, being error prone and confusing to the reader. Given that the on-stack property is fixed by the ABI, can you not handle it with an appropriate subclass?

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PR: https://git.openjdk.java.net/panama-foreign/pull/601