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From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: kernel test robot <lkp@intel.com>, ardb@kernel.org
Cc: "Justin M. Forbes" <jforbes@fedoraproject.org>,
	llvm@lists.linux.dev, kbuild-all@lists.01.org,
	linux-kernel@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Jason A. Donenfeld" <zx2c4@kernel.org>
Subject: Re: [linux-stable-rc:linux-5.15.y 6874/8723] arch/arm/lib/xor-neon.c:30:2: warning: This code requires at least version 4.6 of GCC
Date: Mon, 25 Jul 2022 00:39:53 +0200	[thread overview]
Message-ID: <Yt3KObFVIUI2mFGt@zx2c4.com> (raw)
In-Reply-To: <202207250449.BYMZbIA2-lkp@intel.com>

Hi Ard,

On Mon, Jul 25, 2022 at 04:14:48AM +0800, kernel test robot wrote:
> All warnings (new ones prefixed by >>):
> 
> >> arch/arm/lib/xor-neon.c:30:2: warning: This code requires at least version 4.6 of GCC [-W#warnings]
>    #warning This code requires at least version 4.6 of GCC
>     ^
>    1 warning generated.
> 
> 
> vim +30 arch/arm/lib/xor-neon.c
> 
> 01956597cbc46d Ard Biesheuvel 2013-05-17  16  
> 01956597cbc46d Ard Biesheuvel 2013-05-17  17  /*
> 01956597cbc46d Ard Biesheuvel 2013-05-17  18   * Pull in the reference implementations while instructing GCC (through
> 01956597cbc46d Ard Biesheuvel 2013-05-17  19   * -ftree-vectorize) to attempt to exploit implicit parallelism and emit
> 01956597cbc46d Ard Biesheuvel 2013-05-17  20   * NEON instructions.
> 01956597cbc46d Ard Biesheuvel 2013-05-17  21   */
> 01956597cbc46d Ard Biesheuvel 2013-05-17  22  #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
> 01956597cbc46d Ard Biesheuvel 2013-05-17  23  #pragma GCC optimize "tree-vectorize"
> 01956597cbc46d Ard Biesheuvel 2013-05-17  24  #else
> 01956597cbc46d Ard Biesheuvel 2013-05-17  25  /*
> 01956597cbc46d Ard Biesheuvel 2013-05-17  26   * While older versions of GCC do not generate incorrect code, they fail to
> 01956597cbc46d Ard Biesheuvel 2013-05-17  27   * recognize the parallel nature of these functions, and emit plain ARM code,
> 01956597cbc46d Ard Biesheuvel 2013-05-17  28   * which is known to be slower than the optimized ARM code in asm-arm/xor.h.
> 01956597cbc46d Ard Biesheuvel 2013-05-17  29   */
> 01956597cbc46d Ard Biesheuvel 2013-05-17 @30  #warning This code requires at least version 4.6 of GCC
> 01956597cbc46d Ard Biesheuvel 2013-05-17  31  #endif
> 01956597cbc46d Ard Biesheuvel 2013-05-17  32  

Does this file need a depends on ≥4.6 thing in Kconfig? Or is something
else happening here since 4.6 isn't even supported by the kernel these
days?

Jason

WARNING: multiple messages have this Message-ID (diff)
From: Jason A. Donenfeld <Jason@zx2c4.com>
To: kbuild-all@lists.01.org
Subject: Re: [linux-stable-rc:linux-5.15.y 6874/8723] arch/arm/lib/xor-neon.c:30:2: warning: This code requires at least version 4.6 of GCC
Date: Mon, 25 Jul 2022 16:58:26 +0000	[thread overview]
Message-ID: <Yt3KObFVIUI2mFGt@zx2c4.com> (raw)
In-Reply-To: <202207250449.BYMZbIA2-lkp@intel.com>

[-- Attachment #1: Type: text/plain, Size: 1953 bytes --]

Hi Ard,

On Mon, Jul 25, 2022 at 04:14:48AM +0800, kernel test robot wrote:
> All warnings (new ones prefixed by >>):
> 
> >> arch/arm/lib/xor-neon.c:30:2: warning: This code requires at least version 4.6 of GCC [-W#warnings]
>    #warning This code requires at least version 4.6 of GCC
>     ^
>    1 warning generated.
> 
> 
> vim +30 arch/arm/lib/xor-neon.c
> 
> 01956597cbc46d Ard Biesheuvel 2013-05-17  16  
> 01956597cbc46d Ard Biesheuvel 2013-05-17  17  /*
> 01956597cbc46d Ard Biesheuvel 2013-05-17  18   * Pull in the reference implementations while instructing GCC (through
> 01956597cbc46d Ard Biesheuvel 2013-05-17  19   * -ftree-vectorize) to attempt to exploit implicit parallelism and emit
> 01956597cbc46d Ard Biesheuvel 2013-05-17  20   * NEON instructions.
> 01956597cbc46d Ard Biesheuvel 2013-05-17  21   */
> 01956597cbc46d Ard Biesheuvel 2013-05-17  22  #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
> 01956597cbc46d Ard Biesheuvel 2013-05-17  23  #pragma GCC optimize "tree-vectorize"
> 01956597cbc46d Ard Biesheuvel 2013-05-17  24  #else
> 01956597cbc46d Ard Biesheuvel 2013-05-17  25  /*
> 01956597cbc46d Ard Biesheuvel 2013-05-17  26   * While older versions of GCC do not generate incorrect code, they fail to
> 01956597cbc46d Ard Biesheuvel 2013-05-17  27   * recognize the parallel nature of these functions, and emit plain ARM code,
> 01956597cbc46d Ard Biesheuvel 2013-05-17  28   * which is known to be slower than the optimized ARM code in asm-arm/xor.h.
> 01956597cbc46d Ard Biesheuvel 2013-05-17  29   */
> 01956597cbc46d Ard Biesheuvel 2013-05-17 @30  #warning This code requires at least version 4.6 of GCC
> 01956597cbc46d Ard Biesheuvel 2013-05-17  31  #endif
> 01956597cbc46d Ard Biesheuvel 2013-05-17  32  

Does this file need a depends on ≥4.6 thing in Kconfig? Or is something
else happening here since 4.6 isn't even supported by the kernel these
days?

Jason

  reply	other threads:[~2022-07-24 22:39 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-24 20:14 [linux-stable-rc:linux-5.15.y 6874/8723] arch/arm/lib/xor-neon.c:30:2: warning: This code requires at least version 4.6 of GCC kernel test robot
2022-07-24 22:39 ` Jason A. Donenfeld [this message]
2022-07-25 16:58   ` Jason A. Donenfeld
2022-07-25  5:42   ` Ard Biesheuvel
2022-07-25  5:42     ` Ard Biesheuvel
2022-07-25  8:49     ` Greg Kroah-Hartman
2022-07-25  8:49       ` Greg Kroah-Hartman
2022-07-25 12:41       ` Ard Biesheuvel
2022-07-25 12:41         ` Ard Biesheuvel
2022-07-25 12:55         ` Arnd Bergmann
2022-07-25 12:55           ` Arnd Bergmann
2022-07-25 14:35           ` Arnd Bergmann
2022-07-25 14:35             ` Arnd Bergmann
2022-07-30 14:33             ` Greg Kroah-Hartman
2022-07-30 14:33               ` Greg Kroah-Hartman
2022-07-30 23:15               ` Jason A. Donenfeld
2022-07-30 23:15                 ` Jason A. Donenfeld
2022-07-31 10:13                 ` Greg Kroah-Hartman
2022-07-31 10:13                   ` Greg Kroah-Hartman
2022-07-25 12:59         ` Greg Kroah-Hartman
2022-07-25 12:59           ` Greg Kroah-Hartman

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