From: Richard Earnshaw <Richard.Earnshaw@foss.arm.com>
To: Jojo R <rjiejie@linux.alibaba.com>,
GCC Development <gcc@gcc.gnu.org>,
Peter Bergner <bergner@linux.ibm.com>
Subject: Re: How to describe ‘earlyclobber’ explicitly for specific source operand ?
Date: Tue, 23 Nov 2021 12:22:53 +0000 [thread overview]
Message-ID: <e617004b-47fd-5bc5-64e6-37b1d972618f@foss.arm.com> (raw)
In-Reply-To: <63f7d2b4-16f3-4f2b-b846-cc6d5a55601c@Spark>
On 22/11/2021 06:40, Jojo R via Gcc wrote:
>
> — Jojo
> 在 2021年11月20日 +0800 AM6:11，Peter Bergner <bergner@linux.ibm.com>，写道：
>> On 11/19/21 1:28 AM, Jojo R via Gcc wrote:
>>> We know gcc supply earlyclobber function to avoid register overlap,
>>>
>>> but it can not describe explicitly for specific source operand, is it right ?
>>
>> You add the early clobber to the OUTPUT operand(s) that can clobber any of the
>> input source operands. You don't mark the source operands that could be clobbered.
> Yes, so we need to enhance the early clobber to cover this scene ?
>>
>> Peter
You can write alternatives that explicitly tie a source to the
destination, provided that the source and destination are the same size.
See the Arm backend for examples.
R.
prev parent reply other threads:[~2021-11-23 12:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <eb109969-0133-49eb-b392-b35a065f12ba@Spark>
2021-11-19 7:28 ` Jojo R
2021-11-19 21:54 ` Peter Bergner
2021-11-22 6:40 ` Jojo R
2021-11-23 12:22 ` Richard Earnshaw [this message]
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