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| author | Wilco Dijkstra <wdijkstr@arm.com> | 2018-02-12 10:42:42 +0000 |
|---|---|---|
| committer | Wilco Dijkstra <wdijkstr@arm.com> | 2018-02-12 10:47:09 +0000 |
| commit | c3d466cba1692708a19c6ff829d0386c83a0c6e5 (patch) | |
| tree | d01ce6103dc25d3b662898c3429b8b103b8d3155 /math | |
| parent | 7bb087bd7bfe3616c4c0974a3f7352b593353ea5 (diff) | |
| download | glibc-c3d466cba1692708a19c6ff829d0386c83a0c6e5.tar.gz glibc-c3d466cba1692708a19c6ff829d0386c83a0c6e5.tar.xz glibc-c3d466cba1692708a19c6ff829d0386c83a0c6e5.zip | |
Remove slow paths from pow
Remove the slow paths from pow. Like several other double precision math functions, pow is exactly rounded. This is not required from math functions and causes major overheads as it requires multiple fallbacks using higher precision arithmetic if a result is close to 0.5ULP. Ridiculous slowdowns of up to 100000x have been reported when the highest precision path triggers. All GLIBC math tests pass on AArch64 and x64 (with ULP of pow set to 1). The worst case error is ~0.506ULP. A simple test over a few hundred million values shows pow is 10% faster on average. This fixes BZ #13932. [BZ #13932] * sysdeps/ieee754/dbl-64/uexp.h (err_1): Remove. * benchtests/pow-inputs: Update comment for slow path cases. * manual/probes.texi (slowpow_p10): Delete removed probe. (slowpow_p10): Likewise. * math/Makefile: Remove halfulp.c and slowpow.c. * sysdeps/aarch64/libm-test-ulps: Set ULP of pow to 1. * sysdeps/generic/math_private.h (__exp1): Remove error argument. (__halfulp): Remove. (__slowpow): Remove. * sysdeps/i386/fpu/halfulp.c: Delete file. * sysdeps/i386/fpu/slowpow.c: Likewise. * sysdeps/ia64/fpu/halfulp.c: Likewise. * sysdeps/ia64/fpu/slowpow.c: Likewise. * sysdeps/ieee754/dbl-64/e_exp.c (__exp1): Remove error argument, improve comments and add error analysis. * sysdeps/ieee754/dbl-64/e_pow.c (__ieee754_pow): Add error analysis. (power1): Remove function: (log1): Remove error argument, add error analysis. (my_log2): Remove function. * sysdeps/ieee754/dbl-64/halfulp.c: Delete file. * sysdeps/ieee754/dbl-64/slowpow.c: Likewise. * sysdeps/m68k/m680x0/fpu/halfulp.c: Likewise. * sysdeps/m68k/m680x0/fpu/slowpow.c: Likewise. * sysdeps/powerpc/power4/fpu/Makefile: Remove CPPFLAGS-slowpow.c. * sysdeps/x86_64/fpu/libm-test-ulps: Set ULP of pow to 1. * sysdeps/x86_64/fpu/multiarch/Makefile: Remove slowpow-fma.c, slowpow-fma4.c, halfulp-fma.c, halfulp-fma4.c. * sysdeps/x86_64/fpu/multiarch/e_pow-fma.c (__slowpow): Remove define. * sysdeps/x86_64/fpu/multiarch/e_pow-fma4.c (__slowpow): Likewise. * sysdeps/x86_64/fpu/multiarch/halfulp-fma.c: Delete file. * sysdeps/x86_64/fpu/multiarch/halfulp-fma4.c: Likewise. * sysdeps/x86_64/fpu/multiarch/slowpow-fma.c: Likewise. * sysdeps/x86_64/fpu/multiarch/slowpow-fma4.c: Likewise.
Diffstat (limited to 'math')
| -rw-r--r-- | math/Makefile | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/math/Makefile b/math/Makefile index 718b06d246..8152011c22 100644 --- a/math/Makefile +++ b/math/Makefile @@ -123,9 +123,9 @@ type-ldouble-yes := ldouble # double support type-double-suffix := -type-double-routines := branred doasin dosincos halfulp mpa mpatan2 \ +type-double-routines := branred doasin dosincos mpa mpatan2 \ mpatan mpexp mplog mpsqrt mptan sincos32 slowexp \ - slowpow sincostab k_rem_pio2 + sincostab k_rem_pio2 # float support type-float-suffix := f |