From: Ingo Molnar <mingo@elte.hu>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Mauro Carvalho Chehab <mchehab@redhat.com>,
Eric Dumazet <eric.dumazet@gmail.com>,
mingo@redhat.com, linux-kernel@vger.kernel.org,
suresh.b.siddha@intel.com, tglx@linutronix.de, avi@redhat.com,
linux-tip-commits@vger.kernel.org
Subject: Re: Does anyone care about gcc 3.x support for x86 anymore?
Date: Thu, 20 May 2010 14:44:53 +0200 [thread overview]
Message-ID: <20100520124453.GC2734@elte.hu> (raw)
In-Reply-To: <4BF48569.7080203@zytor.com>
* H. Peter Anvin <hpa@zytor.com> wrote:
> On 05/19/2010 04:10 PM, Mauro Carvalho Chehab wrote:
> >
> > However, if the problems are just performance/dead
> > code removal, I would just add a big warning if
> > someone tries to compile x86 with it. I don't like
> > very much the idea of having different minimum gcc
> > requirements for each architecture, except if gcc is
> > producing a broken code.
> >
>
> I should clarify the problem. The problems we have seen
> are related to constant propagation, which causes gcc3
> to die when there is an assembly constraint like:
>
> asm("..." : : "i" (foo));
>
> ... since "foo" isn't constant as far as it is
> concerned. We can put in workarounds, but it's real
> effort to keep it alive that probably isn't well spent.
>
> Similarly, lack of constant propagation can cause code
> that should have been compile-time removed to still be
> there, causing link failures.
Put in a deprecation warning first perhaps?
Ingo
next prev parent reply other threads:[~2010-05-20 12:45 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-06 8:45 [PATCH v3 0/2] x86 FPU API Avi Kivity
2010-05-06 8:45 ` [PATCH v3 1/2] x86: eliminate TS_XSAVE Avi Kivity
2010-05-10 20:39 ` [tip:x86/fpu] x86: Eliminate TS_XSAVE tip-bot for Avi Kivity
2010-05-12 0:18 ` [tip:x86/fpu] x86, fpu: Use the proper asm constraint in use_xsave() tip-bot for H. Peter Anvin
2010-05-12 1:06 ` [tip:x86/fpu] x86: Add new static_cpu_has() function using alternatives tip-bot for H. Peter Anvin
2010-05-18 20:10 ` Eric Dumazet
2010-05-18 20:43 ` H. Peter Anvin
2010-05-18 20:57 ` H. Peter Anvin
2010-05-18 21:11 ` Eric Dumazet
2010-05-18 21:31 ` H. Peter Anvin
2010-05-18 21:38 ` Does anyone care about gcc 3.x support for x86 anymore? H. Peter Anvin
2010-05-19 23:10 ` Mauro Carvalho Chehab
2010-05-20 0:39 ` H. Peter Anvin
2010-05-20 0:42 ` H. Peter Anvin
2010-05-20 12:44 ` Ingo Molnar [this message]
2010-05-18 20:58 ` [tip:x86/fpu] x86: Add new static_cpu_has() function using alternatives H. Peter Anvin
2010-05-18 21:31 ` Eric Dumazet
2010-05-27 20:12 ` [tip:x86/urgent] x86, cpufeature: Unbreak compile with gcc 3.x tip-bot for H. Peter Anvin
2010-05-12 1:06 ` [tip:x86/fpu] x86, fpu: Use static_cpu_has() to implement use_xsave() tip-bot for H. Peter Anvin
2010-05-06 8:45 ` [PATCH v3 2/2] x86: Introduce 'struct fpu' and related API Avi Kivity
2010-05-10 20:39 ` [tip:x86/fpu] " tip-bot for Avi Kivity
2010-05-10 20:40 ` [tip:x86/fpu] x86, fpu: Unbreak FPU emulation tip-bot for H. Peter Anvin
2010-05-10 8:48 ` [PATCH v3 0/2] x86 FPU API Avi Kivity
2010-05-10 15:24 ` H. Peter Anvin
-- strict thread matches above, loose matches on Subject: below --
2010-05-19 1:19 Does anyone care about gcc 3.x support for *x86* anymore? H. Peter Anvin
2010-05-19 7:13 ` Ingo Molnar
2010-05-19 13:38 ` Andi Kleen
2010-05-19 14:08 ` H. Peter Anvin
2010-05-19 22:45 ` Justin P. Mattock
2010-05-20 18:37 ` Martin Michlmayr
2010-05-20 19:56 ` Miguel Ojeda
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