linux-kernel - Re: [PATCH 46/74] x86, lto: Disable fancy hweight optimizations for LTO

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Message-ID: <50320027.1010809@redhat.com>
Date:	Mon, 20 Aug 2012 12:15:19 +0300
From:	Avi Kivity <avi@...hat.com>
To:	Andi Kleen <andi@...stfloor.org>
CC:	linux-kernel@...r.kernel.org, x86@...nel.org, mmarek@...e.cz,
	linux-kbuild@...r.kernel.org, JBeulich@...e.com,
	akpm@...ux-foundation.org, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 46/74] x86, lto: Disable fancy hweight optimizations for
 LTO

On 08/19/2012 05:56 AM, Andi Kleen wrote:
> From: Andi Kleen <ak@...ux.intel.com>
> 
> The fancy x86 hweight uses different compiler options for the
> hweight file. This does not work with LTO. Just disable the optimization
> with LTO
> 
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> ---
>  arch/x86/Kconfig                    |    5 +++--
>  arch/x86/include/asm/arch_hweight.h |    9 +++++++++
>  2 files changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 8ec3a1a..9382b09 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -224,8 +224,9 @@ config X86_32_LAZY_GS
>  
>  config ARCH_HWEIGHT_CFLAGS
>  	string
> -	default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
> -	default "-fcall-saved-rdi -fcall-saved-rsi -fcall-saved-rdx -fcall-saved-rcx -fcall-saved-r8 -fcall-saved-r9 -fcall-saved-r10 -fcall-saved-r11" if X86_64
> +	default "-fcall-saved-ecx -fcall-saved-edx" if X86_32 && !LTO
> +	default "-fcall-saved-rdi -fcall-saved-rsi -fcall-saved-rdx -fcall-saved-rcx -fcall-saved-r8 -fcall-saved-r9 -fcall-saved-r10 -fcall-saved-r11" if X86_64 && !LTO
> +	default "" if LTO
>  

Seems heavy handed.  How about using __attribute__((optimize(...))) instead?


-- 
error compiling committee.c: too many arguments to function
--
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