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Re: [PATCH 1/3] New generic sincosf

From: Rajalakshmi Srinivasaraghavan <raji at linux dot vnet dot ibm dot com>
To: "H.J. Lu" <hjl dot tools at gmail dot com>
Cc: GNU C Library <libc-alpha at sourceware dot org>
Date: Mon, 1 Jan 2018 15:46:18 +0530
Subject: Re: [PATCH 1/3] New generic sincosf
Authentication-results: sourceware.org; auth=none
References: <1513143801-3290-1-git-send-email-raji@linux.vnet.ibm.com> <alpine.DEB.2.20.1712150029250.5909@digraph.polyomino.org.uk> <CAMe9rOq3VHYR5prK-oHLB+YjHEJXKU8+gCU_XTsOX12n3RvcQA@mail.gmail.com> <alpine.DEB.2.20.1712151408290.3687@digraph.polyomino.org.uk> <CAMe9rOo-gR0XUuZ2oxEwMj71hukysA75XEhqmsfnx_x414ieqw@mail.gmail.com> <alpine.DEB.2.20.1712151547280.13157@digraph.polyomino.org.uk> <CAMe9rOqD=yXstUu1QZ8zBn268UsQL_iC-VxEntpYaKn_kbwcCA@mail.gmail.com> <alpine.DEB.2.20.1712151620250.13157@digraph.polyomino.org.uk> <CAMe9rOq+-Vd=VOku-gbH=xSUd00rD=Sm6MhCvD6Sf26rMJ02hg@mail.gmail.com> <CAMe9rOq6PZ17V-sMJm50Lxw8Ko+4b37fb8n6JDP_F+m8iSG-Vg@mail.gmail.com> <alpine.DEB.2.20.1712152050110.860@digraph.polyomino.org.uk> <45451ed9-df1f-ff5e-f2fd-552e705d100c@linux.vnet.ibm.com> <CAMe9rOpZmAtEdwPpe0sS1mswjhA_PT_+oQUBguBm5JqX--9kaw@mail.gmail.com> <9bb5759b-50c3-9187-dc32-044936a57433@linux.vnet.ibm.com> <CAMe9rOqpqRFZhnnfg4w1mANNfu0QjAoZKoW2ZpDLvopWSNqJew@mail.gmail.com>



On 12/19/2017 10:05 PM, H.J. Lu wrote:

On Sun, Dec 17, 2017 at 7:26 PM, Rajalakshmi Srinivasaraghavan
<raji@linux.vnet.ibm.com> wrote:



On 12/16/2017 08:13 PM, H.J. Lu wrote:


On Sat, Dec 16, 2017 at 12:52 AM, Rajalakshmi Srinivasaraghavan
<raji@linux.vnet.ibm.com> wrote:




On 12/16/2017 02:20 AM, Joseph Myers wrote:



On Fri, 15 Dec 2017, H.J. Lu wrote:

One comment,  should sysdeps/ieee754/flt-32/s_sincos.h be renamed
to  sysdeps/ieee754/flt-32/s_sincosf.h?




Yes, I think so.


Pushed as 984ae9967b49830173490a33ae6130880f3f70d9 with the file
name changed as s_sincosf.h.  Thanks for the review.


I noticed that sysdeps/x86_64/fpu/s_sincosf.S is still faster:

Generic:

      "max": 276.971,
      "min": 10.813,
      "mean": 29.3755

SSE2:

      "max": 138.795,
      "min": 11.686,
      "mean": 22.9463

The SSE2 is 28% faster.  Do they use the same algorithm?



Yes, they are same. One small difference is generic version calls
reduced_sin() and reduced_cos() whereas asm version handles both in the same
branch for reconstruction.


Can generic version do the same?


I don't see any difference in mean value with that change.


--
Thanks
Rajalakshmi S

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