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Message-ID: <20200206220834.GD23985@port70.net>
Date: Thu, 6 Feb 2020 23:08:34 +0100
From: Szabolcs Nagy <nsz@...t70.net>
To: musl@...ts.openwall.com
Subject: Re: Q: dealing with missing removal of excess precision
* Rich Felker <dalias@...c.org> [2020-02-06 15:02:58 -0500]:
> #include <math.h>
>
> int main()
> {
> double x, a=0;
> for (x=-2; x<2; x+=0x1p-24)
> a += exp(x);
> return (long long)a;
> }
same here on my old core i5 x86_64 laptop
asm: 3.13s
c : 2.67s
optimized-routines benchmark is
asm:
exp rthruput: 44.18 ns/elem 44176510 ns in [-9.9 9.9]
exp latency: 48.32 ns/call 48317455 ns in [-9.9 9.9]
expf rthruput: 28.59 ns/elem 28586714 ns in [-9.9 9.9]
expf latency: 44.54 ns/call 44536368 ns in [-9.9 9.9]
exp2 rthruput: 42.63 ns/elem 42634692 ns in [-9.9 9.9]
exp2 latency: 46.54 ns/call 46543915 ns in [-9.9 9.9]
exp2f rthruput: 27.75 ns/elem 27751888 ns in [-9.9 9.9]
exp2f latency: 42.91 ns/call 42908855 ns in [-9.9 9.9]
c:
exp rthruput: 34.74 ns/elem 34735750 ns in [-9.9 9.9]
exp latency: 38.88 ns/call 38879834 ns in [-9.9 9.9]
expf rthruput: 14.88 ns/elem 14878824 ns in [-9.9 9.9]
expf latency: 26.74 ns/call 26740464 ns in [-9.9 9.9]
exp2 rthruput: 31.62 ns/elem 31622777 ns in [-9.9 9.9]
exp2 latency: 35.76 ns/call 35760590 ns in [-9.9 9.9]
exp2f rthruput: 14.87 ns/elem 14869128 ns in [-9.9 9.9]
exp2f latency: 24.80 ns/call 24795727 ns in [-9.9 9.9]
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