[PATCH] arm64: Remove AArch64 X30 redundant register alias

[naohirot at fujitsu.com]

Hi Robin, Marc,

Thank you for your quick feedbacks!

> From: Robin Murphy <robin.murphy at arm.com>
> Sent: Wednesday, July 14, 2021 8:39 PM

> On 2021-07-14 10:54, Marc Zyngier wrote:
> > On Tue, 13 Jul 2021 14:29:45 +0100,
> > Naohiro Tamura <naohirot at fujitsu.com> wrote:

> >> -/*
> >> - * Register aliases.
> >> - */
> >> -lr	.req	x30		// link register
> >> -
> >>   /*
> >>    * Vector entry
> >>    */
> >
> > I seem to vaguely remember that this isn't always defined, see [1] for
> > a recent example. Dropping it altogether may end-up being pretty
> > disruptive.
> 
> Right, the built-in alias was only introduced a few years ago in
> binutils 2.29 (where it initially caused problems itself by being a bit
> overzealous[2]), but our current minimum version is 2.23, so we still
> need this for older but still-supported toolchains (e.g. I expect the
> Linaro GCC 7-based releases with binutils 2.28 are still being used).

I confirmed that binutils 2.23 doesn't have the alias [3].
So I withdraw this patch.

[3] https://sourceware.org/binutils/docs-2.23/as/AArch64-Directives.html#AArch64-Directives

p.s. I have learned how to submit a patch 😊
Thanks.
Naohiro