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Re: MIPS: Get rid of branches to .subsections.

To: Ralf Baechle <ralf@linux-mips.org>
Subject: Re: MIPS: Get rid of branches to .subsections.
From: Matt Fleming <matt@console-pimps.org>
Date: Wed, 18 Aug 2010 14:33:11 +0100
Cc: linux-mips@linux-mips.org, Paul Gortmaker <paul.gortmaker@windriver.com>, gcc@gcc.gnu.org
In-reply-to: <20100818124310.GA23744@linux-mips.org>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20100818124310.GA23744@linux-mips.org>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.18 (2008-05-17)
On Wed, Aug 18, 2010 at 01:43:10PM +0100, Ralf Baechle wrote:
> It was a nice optimization - on paper at least.  In practice it results in
> branches that may exceed the maximum legal range for a branch.  We can
> fight that problem with -ffunction-sections but -ffunction-sections again
> is incompatible with -pg used by the function tracer.

I'm pretty sure that this check in GCC is historic. I know it has been
discussed in the past but I don't think a solution was ever reached
and my google skills are failing me, I can't find the discussion in
the archives.

We maintain a patch at work that removes this check because we always
use -ffunction-sections and also needed to be able to profile
things. We've never seen any issues.

GCC guys, is this check still needed? Does anyone know which
architecture required this restriction?

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