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Date: Fri, 18 Dec 2020 09:28:12 +0100
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From: Paul Zimmermann <Paul.Zimmermann@inria.fr>
To: Siddhesh Poyarekar <siddhesh@sourceware.org>
Cc: libc-alpha@sourceware.org, joseph@codesourcery.com
In-Reply-To: <20201218070926.917194-1-siddhesh@sourceware.org> (message from
 Siddhesh Poyarekar via Libc-alpha on Fri, 18 Dec 2020 12:39:26 +0530)
Subject: Re: [COMMITTED] ieee754: Remove slow paths from asin and acos
References: <20201218070926.917194-1-siddhesh@sourceware.org>
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       Hi,

> Date: Fri, 18 Dec 2020 12:39:26 +0530
> From: Siddhesh Poyarekar via Libc-alpha <libc-alpha@sourceware.org>
> 
> Looks like this patchset was approved but never committed.  I have
> pushed it now:
> 
> https://sourceware.org/pipermail/glibc-cvs/2020q4/071274.html
> https://sourceware.org/pipermail/glibc-cvs/2020q4/071275.html
> 
> Siddhesh

note that acos() was not correctly rounded before (x=0x1.fffff3634acd6p-1
gave an error of 0.5000000044534775 ulps [1]).

I did run "make bench" in 2.32 and after those patches.

2.32:
  "acos": {
   "": {
    "duration": 3.63669e+09,
    "iterations": 2.43e+07,
    "max": 892.2,
    "min": 15.357,
    "mean": 149.658
   },
  "asin": {
   "": {
    "duration": 3.58039e+09,
    "iterations": 2.5e+07,
    "max": 488.568,
    "min": 15.231,
    "mean": 143.216
   },

after:
  "acos": {
   "": {
    "duration": 3.65234e+09,
    "iterations": 2.43e+07,
    "max": 1015,
    "min": 15.456,
    "mean": 150.302
   },
  "asin": {
   "": {
    "duration": 3.61159e+09,
    "iterations": 2.5e+07,
    "max": 1011.85,
    "min": 16.131,
    "mean": 144.464
   },

It does not seem the maximal time did decrease. Can someone else check?

Paul

[1] https://members.loria.fr/PZimmermann/papers/accuracy.pdf