From 94d80dfc7349b3545942fbbb1d5ff05f354afdf8 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Tue, 5 Dec 2017 15:27:03 -0200 Subject: math: Use sign as double for reduced case in sinf This patch avoid an extra floating point to integer conversion in reduced internal function for generic sinf by defining the sign as double instead of integers. There is no much difference on Haswell with GCC 7.2.1: Before After min 9.11 9.108 mean 21.982 21.9224 However H.J. Lu reported gains on Skylake: Before: "sinf": { "": { "duration": 3.4044e+10, "iterations": 1.9942e+09, "max": 141.106, "min": 7.704, "mean": 17.0715 } } After: "sinf": { "": { "duration": 3.40665e+10, "iterations": 2.03199e+09, "max": 95.994, "min": 7.704, "mean": 16.765 } } Checked on x86_64-linux-gnu. * sysdeps/ieee754/flt-32/s_sinf.c (ones): Define as double. (reduced): Use ones as double instead of integer. --- sysdeps/ieee754/flt-32/s_sinf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'sysdeps/ieee754/flt-32') diff --git a/sysdeps/ieee754/flt-32/s_sinf.c b/sysdeps/ieee754/flt-32/s_sinf.c index 8b98573ae4..418d4487c5 100644 --- a/sysdeps/ieee754/flt-32/s_sinf.c +++ b/sysdeps/ieee754/flt-32/s_sinf.c @@ -75,7 +75,7 @@ static const double invpio4_table[] = { 0x1.0e4107cp-169 }; -static const int ones[] = { +1, -1 }; +static const double ones[] = { 1.0, -1.0 }; /* Compute the sine value using Chebyshev polynomials where THETA is the range reduced absolute value of the input @@ -92,7 +92,7 @@ reduced (const double theta, const unsigned int n, const double theta2 = theta * theta; /* We are operating on |x|, so we need to add back the original signbit for sinf. */ - int sign; + double sign; /* Determine positive or negative primary interval. */ sign = ones[((n >> 2) & 1) ^ signbit]; /* Are we in the primary interval of sin or cos? */ -- cgit 1.4.1