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From: Florian Weimer <fweimer@redhat.com>
To: Jeff Law via Gcc <gcc@gcc.gnu.org>
Cc: Paul Koning <paulkoning@comcast.net>,  Iain Sandoe <iain@sandoe.co.uk>,
 Jeff Law <jeffreyalaw@gmail.com>
Subject: Re: Help with an ABI peculiarity
References: <CD187C76-0620-457C-A0B7-B4ADBB6014FB@sandoe.co.uk>
 <DB1CB1BA-486C-4940-B824-FEC2ED9AD7EE@comcast.net>
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Date: Mon, 10 Jan 2022 09:38:32 +0100
In-Reply-To: <6238c748-c7f3-159b-0464-2175eb6d1b0a@gmail.com> (Jeff Law via
 Gcc's message of "Sat, 8 Jan 2022 09:35:52 -0700")
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* Jeff Law via Gcc:

> Most targets these days use registers for parameter passing and
> obviously we can run out of registers on all of them.=C2=A0 The key
> property is the size/alignment of the argument differs depending on if
> it's pass in a register (get promoted) or passed in memory (not
> promoted).=C2=A0 I'm not immediately aware of another ABI with that
> feature.=C2=A0 Though I haven't really gone looking.

I think what AArch64 Darwin does is not compatible with a GCC extension
that allows calling functions defined with a prototype without it (for
pre-ISO-C compatibility).  Given that, anyone defining an ABI in
parallel with a GCC implementation probably has paused, reconsidered
what they were doing, and adjusted the ABI for K&R compatibility.

Thanks,
Florian