linux-mips
[Top] [All Lists]

Re: [PATCH]: R10000 Needs LL/SC Workaround in Gcc

To: Richard Sandiford <rdsandiford@googlemail.com>
Subject: Re: [PATCH]: R10000 Needs LL/SC Workaround in Gcc
From: "Maciej W. Rozycki" <macro@linux-mips.org>
Date: Sat, 1 Nov 2008 20:33:03 +0000 (GMT)
Cc: Kumba <kumba@gentoo.org>, Ralf Baechle <ralf@linux-mips.org>, gcc-patches@gcc.gnu.org, Linux MIPS List <linux-mips@linux-mips.org>
In-reply-to: <87abcjibsl.fsf@firetop.home>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <490A90F4.6040601@gentoo.org> <490C05A9.9070707@gentoo.org> <87abcjibsl.fsf@firetop.home>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Alpine 1.10 (LFD 962 2008-03-14)
On Sat, 1 Nov 2008, Richard Sandiford wrote:

> There are two ways we could handle this:
> 
>   - Make -mfix-r10000 require -mbranch-likely.  (It mustn't _imply_
>     -mbranch-likely.  It should simply check that -mbranch-likely is
>     already in effect.)
> 
>   - Make -mfix-r10000 insert nops when -mbranch-likely is not in effect.

 If I recall right, these is something special about the pipeline in this 
context making the branch-likely instructions the only ones that work.  
Which would make the option you proposed first the only viable.  I am not 
absolutely sure and I have no reference handy.  Perhaps Ralf or someone at 
linux-mips will know?

  Maciej

<Prev in Thread] Current Thread [Next in Thread>