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Re: [PATCH] Compile AVX libm functions with -mavx
- From: Matt Turner <mattst88 at gmail dot com>
- To: Andreas Jaeger <aj at suse dot com>
- Cc: libc-alpha at sourceware dot org
- Date: Tue, 2 Oct 2012 09:58:34 -0700
- Subject: Re: [PATCH] Compile AVX libm functions with -mavx
- References: <20121002135325.GA751@gmail.com> <506AFB9A.9030601@suse.com>
On Tue, Oct 2, 2012 at 7:35 AM, Andreas Jaeger <aj@suse.com> wrote:
> On 10/02/2012 03:53 PM, H.J. Lu wrote:
>>
>> Hi,
>>
>> This patch compiles AVX libm functions with -mavx. It reduces text size
>> of libm.so by about 1%:
>>
>> Before
>>
>> gnu-tools-1:pts/4[17]> size libm.so
>> text data bss dec hex filename
>> 1027977 876 72 1028925 fb33d libm.so
>>
>> After:
>>
>> gnu-tools-1:pts/3[25]> size libm.so
>> text data bss dec hex filename
>> 1018017 876 72 1018965 f8c55 libm.so
>>
>> Tested on AVX machine. OK for trunk?
>
>
> textsize is a good metric but what about performance?
I would posit that text size reductions are from fewer move
instructions due to AVX's 3-operand form. As such, performance should
be better.