Date: Mon, 25 Feb 2008 13:33:20 +0000 (UTC) From: Bruce Evans <bde@FreeBSD.org> To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/lib/msun/src e_rem_pio2f.c math_private.h s_cosf.c s_sinf.c s_tanf.c Message-ID: <200802251333.m1PDXKau077565@repoman.freebsd.org>
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bde 2008-02-25 13:33:20 UTC
FreeBSD src repository
Modified files:
lib/msun/src e_rem_pio2f.c math_private.h s_cosf.c
s_sinf.c s_tanf.c
Log:
Change __ieee754_rem_pio2f() to return double instead of float so that
this function and its callers cosf(), sinf() and tanf() don't waste time
converting values from doubles to floats and back for |x| > 9pi/4.
All these functions were optimized a few years ago to mostly use doubles
internally and across the __kernel*() interfaces but not across the
__ieee754_rem_pio2f() interface.
This saves about 40 cycles in cosf(), sinf() and tanf() for |x| > 9pi/4
on amd64 (A64), and about 20 cycles on i386 (A64) (except for cosf()
and sinf() in the upper range). 40 cycles is about 35% for |x| < 9pi/4
<= 2**19pi/2 and about 5% for |x| > 2**19pi/2. The saving is much
larger on amd64 than on i386 since the conversions are not easy to
optimize except on i386 where some of them are automatic and others
are optimized invalidly. amd64 is still about 10% slower in cosf()
and tanf() in the lower range due to conversion overhead.
This also gives a tiny speedup for |x| <= 9pi/4 on amd64 (by simplifying
the code). It also avoids compiler bugs and/or additional slowness
in the conversions on (not yet supported) machines where double_t !=
double.
Revision Changes Path
1.26 +8 -11 src/lib/msun/src/e_rem_pio2f.c
1.26 +1 -1 src/lib/msun/src/math_private.h
1.17 +6 -6 src/lib/msun/src/s_cosf.c
1.16 +6 -6 src/lib/msun/src/s_sinf.c
1.16 +3 -3 src/lib/msun/src/s_tanf.c
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