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Date: Sun, 22 May 2022 21:48:52 +0100 (BST)
From: "Maciej W. Rozycki" <macro@orcam.me.uk>
To: Nathan Chancellor <nathan@kernel.org>
cc: Paul Cercueil <paul@crapouillou.net>, kernel test robot <lkp@intel.com>, 
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    linux-kernel@vger.kernel.org, 
    Thomas Bogendoerfer <tsbogend@alpha.franken.de>, 
    linux-mips <linux-mips@vger.kernel.org>
Subject: Re: arch/mips/include/asm/checksum.h:195:9: error: unsupported inline
 asm: input with type 'unsigned long' matching output with type '__wsum' (aka
 'unsigned int')
In-Reply-To: <Yoe5TafDskZ9JDSW@dev-arch.thelio-3990X>
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On Fri, 20 May 2022, Nathan Chancellor wrote:

> >  It doesn't matter whether there is ADDU or DADDU anymore, given that 
> > commit 198688edbf77 ("MIPS: Fix inline asm input/output type mismatch in 
> > checksum.h used with Clang") has added a redundant 32-bit sign-extension 
> > operation right afterwards, regressing size/performance by an extra 
> > instruction in this performance-critical code as a workaround for a stupid 
> > compiler.
> 
> Shouldn't this concern have been addressed by Tiezhu's follow up?
> 
> https://lore.kernel.org/1617359240-16609-1-git-send-email-yangtiezhu@loongson.cn/
> 
> I guess it never got picked up?

 Still it is a hack.  I have now rewritten this code in plain C instead.

  Maciej

From mboxrd@z Thu Jan  1 00:00:00 1970
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From: Maciej W. Rozycki <macro@orcam.me.uk>
To: kbuild-all@lists.01.org
Subject: Re: arch/mips/include/asm/checksum.h:195:9: error: unsupported inline asm: input with type 'unsigned long' matching output with type '__wsum' (aka 'unsigned int')
Date: Sun, 22 May 2022 21:48:52 +0100
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In-Reply-To: <Yoe5TafDskZ9JDSW@dev-arch.thelio-3990X>
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--===============0934411366531938420==
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On Fri, 20 May 2022, Nathan Chancellor wrote:

> >  It doesn't matter whether there is ADDU or DADDU anymore, given that =

> > commit 198688edbf77 ("MIPS: Fix inline asm input/output type mismatch i=
n =

> > checksum.h used with Clang") has added a redundant 32-bit sign-extensio=
n =

> > operation right afterwards, regressing size/performance by an extra =

> > instruction in this performance-critical code as a workaround for a stu=
pid =

> > compiler.
> =

> Shouldn't this concern have been addressed by Tiezhu's follow up?
> =

> https://lore.kernel.org/1617359240-16609-1-git-send-email-yangtiezhu(a)lo=
ongson.cn/
> =

> I guess it never got picked up?

 Still it is a hack.  I have now rewritten this code in plain C instead.

  Maciej
--===============0934411366531938420==--