Re: [PATCH 1/2] compiler/gcc5: Remove quirk for asm_volatile_goto()

["Martin Liška" <mliska@suse.cz>]

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On 04/14/2015 07:58 PM, Linus Torvalds wrote:
> On Tue, Apr 14, 2015 at 2:25 AM, Martin Liška <mliska@suse.cz> wrote:
>> Remove comments related to GCC 4.x branch and workaround for
>> asm_volatile_goto which is fixed in GCC 5 release.
>
> How sure are you that it is *really* fixed? Because it wasn't, last we saw.
>
> It was originally claimed to be fixed in 4.8.2, but that turned out to
> be wrong. See commit 5631b8fba640 ("compiler/gcc4+: Remove inaccurate
> comment about 'asm goto' miscompiles"), and
>
>      https://lkml.org/lkml/2014/2/12/817
>
> which shows that the bugzilla you reference is at the very least
> unreliable. Apparently the gcc test-case didn't catch all the
> problems.
>
> IOW, just leave the workaround. It has no actual cost, and the gcc bug
> wasn't obviously fully fixed. There are apparently very few users of
> "asm goto" (probably partly because of the limitations of it,
> particularly the "no outputs").
>
>                             Linus
>

Hello Linus.

Agree with you that a bit more defensive approach is reasonable, mainly because
of the actual cost.

Thus, I send updated version of the patch which just removes unrelated GCC 4.x branch
comments.

Thanks,
Martin


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From 9db00c78af98a26685d3e0034d26962167441070 Mon Sep 17 00:00:00 2001
From: mliska <mliska@suse.cz>
Date: Wed, 15 Apr 2015 10:55:14 +0200
Subject: [PATCH 1/2] compiler/gcc5: Remove comments related to GCC 4.x branch.

Signed-off-by: Martin Liska  <mliska@suse.cz>
---
 include/linux/compiler-gcc5.h | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/include/linux/compiler-gcc5.h b/include/linux/compiler-gcc5.h
index efee493..abb03b8 100644
--- a/include/linux/compiler-gcc5.h
+++ b/include/linux/compiler-gcc5.h
@@ -12,10 +12,6 @@
    like BUG(), printk(), panic() etc. [but let's keep them for now for
    older compilers]
 
-   Early snapshots of gcc 4.3 don't support this and we can't detect this
-   in the preprocessor, but we can live with this because they're unreleased.
-   Maketime probing would be overkill here.