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From: Richard Sandiford <richard.sandiford@arm.com>
To: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Mail-Followup-To: Wilco Dijkstra <Wilco.Dijkstra@arm.com>,James Greenhalgh	<James.Greenhalgh@arm.com>,  GCC Patches <gcc-patches@gcc.gnu.org>,  Richard Earnshaw	<Richard.Earnshaw@arm.com>,  Ramana Radhakrishnan	<Ramana.Radhakrishnan@arm.com>,  nd <nd@arm.com>, richard.sandiford@arm.com
Cc: James Greenhalgh	<James.Greenhalgh@arm.com>,  GCC Patches <gcc-patches@gcc.gnu.org>,  Richard Earnshaw	<Richard.Earnshaw@arm.com>,  Ramana Radhakrishnan	<Ramana.Radhakrishnan@arm.com>,  nd <nd@arm.com>
Subject: Re: [PATCH][AArch64] Remove aarch64_frame_pointer_required
References: <DB6PR0801MB205392DA3F942C111AD4572783B60@DB6PR0801MB2053.eurprd08.prod.outlook.com>	<20171107170512.GA30919@arm.com>	<87muzryjs7.fsf@e105548-lin.cambridge.arm.com>	<HE1PR0801MB20589082137557C489367ACE83C60@HE1PR0801MB2058.eurprd08.prod.outlook.com>
Date: Mon, 12 Mar 2018 14:27:00 -0000
In-Reply-To: <HE1PR0801MB20589082137557C489367ACE83C60@HE1PR0801MB2058.eurprd08.prod.outlook.com>	(Wilco Dijkstra's message of "Thu, 1 Mar 2018 20:21:32 +0000")
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Wilco Dijkstra <Wilco.Dijkstra@arm.com> writes:
> Richard Sandiford wrote:
>> But there's the third question of whether the frame pointer is available
>> for general allocation.=C2=A0 By removing frame_pointer_required, we're =
saying
>> that the frame pointer is always available for general use.=C2=A0=20
>
> Unlike on ARM/Thumb-2, the frame pointer is unfortunately never available=
 for
> general allocation on AArch64 - so we cannot use it for something
> actually useful.
> A while back there were mid-end patches proposed to allow general allocat=
ion
> of FP but those weren't accepted.

Ah, missed that, sorry.  So the asm example I gave probably is as far as
the "problem" goes, and the argument can be made that that's just doing
what the user asked for.

Sorry for the noise...

Richard