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| author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2017-12-05 15:27:03 -0200 |
|---|---|---|
| committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2017-12-05 16:27:44 -0200 |
| commit | 94d80dfc7349b3545942fbbb1d5ff05f354afdf8 (patch) | |
| tree | 07984816a08b1592f3a765cc211752fd2a7d3598 | |
| parent | 00d54af7c86cdcabc18c00619c229f49f4978610 (diff) | |
| download | glibc-94d80dfc7349b3545942fbbb1d5ff05f354afdf8.tar glibc-94d80dfc7349b3545942fbbb1d5ff05f354afdf8.tar.gz glibc-94d80dfc7349b3545942fbbb1d5ff05f354afdf8.tar.bz2 glibc-94d80dfc7349b3545942fbbb1d5ff05f354afdf8.zip | |
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.
| -rw-r--r-- | ChangeLog | 5 | ||||
| -rw-r--r-- | sysdeps/ieee754/flt-32/s_sinf.c | 4 |
2 files changed, 7 insertions, 2 deletions
@@ -1,3 +1,8 @@ +2017-12-05 Adhemerval Zanella <adhemerval.zanella@linaro.org> + + * sysdeps/ieee754/flt-32/s_sinf.c (ones): Define as double. + (reduced): Use ones as double instead of integer. + 2017-12-05 Szabolcs Nagy <szabolcs.nagy@arm.com> * sysdeps/ieee754/flt-32/s_sinf.c (sinf): Use isless. 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? */ |