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3e08ff544b
glibc/sysdeps/ieee754/dbl-64
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Szabolcs Nagy 3e08ff544b Add new log2 implementation 
Similar algorithm is used as in log: log2(2^k x) = k + log2(c) + log2(x/c)
where the last term is approximated by a polynomial of x/c - 1, the first
order coefficient is about 1/ln2 in this case.

There is separate code path when fma instruction is not available for
computing x/c - 1 precisely, for which the table size is doubled.

The worst case error is 0.547 ULP (0.55 without fma), the read only
global data size is 1168 bytes (2192 without fma) on aarch64.  The
non-nearest rounding error is less than 1 ULP.

Improvements on Cortex-A72 compared to current glibc master:
log2 thruput: 2.00x in [0.01 11.1]
log2 latency: 2.04x in [0.01 11.1]
log2 thruput: 2.17x in [0.999 1.001]
log2 latency: 2.88x in [0.999 1.001]

Tested on
aarch64-linux-gnu (defined __FP_FAST_FMA)
arm-linux-gnueabihf (!defined __FP_FAST_FMA)
x86_64-linux-gnu (!defined __FP_FAST_FMA)
powerpc64le-linxu-gnu (defined __FP_FAST_FMA)
targets.

	* NEWS: Mention log2 improvements.
	* math/Makefile (type-double-routines): Add e_log2_data.
	* sysdeps/i386/fpu/e_log2_data.c: New file.
	* sysdeps/ia64/fpu/e_log2_data.c: New file.
	* sysdeps/ieee754/dbl-64/e_log2.c: Rewrite.
	* sysdeps/ieee754/dbl-64/e_log2_data.c: New file.
	* sysdeps/ieee754/dbl-64/math_config.h (__log2_data): Add.
	* sysdeps/ieee754/dbl-64/wordsize-64/e_log2.c: Remove.
	* sysdeps/m68k/m680x0/fpu/e_log2_data.c: New file.
2018-09-12 17:36:33 +01:00
..
wordsize-64 Add new log2 implementation 2018-09-12 17:36:33 +01:00
asincos.tbl Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
atnat2.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
atnat.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
branred.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
branred.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
dbl2mpn.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
dla.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
doasin.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
doasin.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
dosincos.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
dosincos.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
e_acos.c
e_acosh.c Rename all __ieee754_sqrt(f/l) calls to sqrt(f/l) 2018-03-15 19:21:36 +00:00
e_asin.c Move math_check_force_underflow macros to separate math-underflow.h. 2018-05-10 00:53:04 +00:00
e_atan2.c Do not include fenv_private.h in math_private.h. 2018-09-03 21:09:04 +00:00
e_atanh.c Do not include math-barriers.h in math_private.h. 2018-05-11 15:11:38 +00:00
e_cosh.c Move math_narrow_eval to separate math-narrow-eval.h. 2018-05-09 00:15:10 +00:00
e_exp2.c Add new exp and exp2 implementations 2018-09-05 16:22:00 +01:00
e_exp10.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
e_exp_data.c Add new exp and exp2 implementations 2018-09-05 16:22:00 +01:00
e_exp.c Add new exp and exp2 implementations 2018-09-05 16:22:00 +01:00
e_fmod.c Consistently use uintN_t not u_intN_t in libm. 2017-08-03 19:55:04 +00:00
e_gamma_r.c Do not include fenv_private.h in math_private.h. 2018-09-03 21:09:04 +00:00
e_hypot.c Move math_check_force_underflow macros to separate math-underflow.h. 2018-05-10 00:53:04 +00:00
e_ilogb.c Format floating routines. 2013-10-17 16:03:24 +02:00
e_j0.c Do not include math-barriers.h in math_private.h. 2018-05-11 15:11:38 +00:00
e_j1.c Move math_check_force_underflow macros to separate math-underflow.h. 2018-05-10 00:53:04 +00:00
e_jn.c Do not include fenv_private.h in math_private.h. 2018-09-03 21:09:04 +00:00
e_lgamma_r.c Move math_narrow_eval to separate math-narrow-eval.h. 2018-05-09 00:15:10 +00:00
e_log2_data.c Add new log2 implementation 2018-09-12 17:36:33 +01:00
e_log2.c Add new log2 implementation 2018-09-12 17:36:33 +01:00
e_log10.c Use fabs(f/l) rather than __fabs 2017-09-29 18:54:24 +01:00
e_log_data.c Add new log implementation 2018-09-12 17:33:30 +01:00
e_log.c Add new log implementation 2018-09-12 17:33:30 +01:00
e_pow.c Add new exp and exp2 implementations 2018-09-05 16:22:00 +01:00
e_remainder.c Do not include fenv_private.h in math_private.h. 2018-09-03 21:09:04 +00:00
e_sinh.c Move math_check_force_underflow macros to separate math-underflow.h. 2018-05-10 00:53:04 +00:00
e_sqrt.c Do not include fenv_private.h in math_private.h. 2018-09-03 21:09:04 +00:00
gamma_product.c Do not include fenv_private.h in math_private.h. 2018-09-03 21:09:04 +00:00
gamma_productf.c Move math_narrow_eval to separate math-narrow-eval.h. 2018-05-09 00:15:10 +00:00
k_rem_pio2.c Fix i686-linux-gnu build with GCC mainline. 2018-05-22 16:55:04 +00:00
k_tan.c
lgamma_neg.c Do not include fenv_private.h in math_private.h. 2018-09-03 21:09:04 +00:00
lgamma_product.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
Makefile Fix CFLAGS override in sysdeps/ieee754/dbl-64 2017-08-24 15:56:11 +01:00
math_config.h Add new log2 implementation 2018-09-12 17:36:33 +01:00
math_err.c Add new exp and exp2 implementations 2018-09-05 16:22:00 +01:00
MathLib.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
mpa-arch.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
mpa.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
mpa.h Remove mplog and mpexp 2018-02-15 12:41:05 +00:00
mpatan2.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
mpatan.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
mpatan.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
mpn2dbl.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
mpsqrt.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
mpsqrt.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
mptan.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
mydefs.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
powtwo.tbl Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
root.tbl Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
s_asinh.c Move math_check_force_underflow macros to separate math-underflow.h. 2018-05-10 00:53:04 +00:00
s_atan.c Do not include fenv_private.h in math_private.h. 2018-09-03 21:09:04 +00:00
s_cbrt.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
s_ceil.c Use libm_alias_double for more dbl-64 functions. 2017-10-03 17:47:35 +00:00
s_copysign.c Use libm_alias_double for some dbl-64 functions. 2017-09-29 23:54:33 +00:00
s_cos.c
s_erf.c Move math_check_force_underflow macros to separate math-underflow.h. 2018-05-10 00:53:04 +00:00
s_expm1.c Do not include math-barriers.h in math_private.h. 2018-05-11 15:11:38 +00:00
s_f32xaddf64.c Add narrowing add functions. 2018-02-10 02:08:43 +00:00
s_f32xdivf64.c Add narrowing divide functions. 2018-05-17 00:40:52 +00:00
s_f32xmulf64.c Add narrowing multiply functions. 2018-05-16 00:05:28 +00:00
s_f32xsubf64.c Add narrowing subtract functions. 2018-03-20 00:34:52 +00:00
s_fabs.c Use libm_alias_double for some dbl-64 functions. 2017-09-29 23:54:33 +00:00
s_fadd.c Add narrowing add functions. 2018-02-10 02:08:43 +00:00
s_fdiv.c Add narrowing divide functions. 2018-05-17 00:40:52 +00:00
s_finite.c Move LDBL_CLASSIFY_COMPAT to its own header. 2018-02-01 21:01:00 +00:00
s_floor.c Use libm_alias_double for more dbl-64 functions. 2017-10-03 17:47:35 +00:00
s_fma.c Do not include fenv_private.h in math_private.h. 2018-09-03 21:09:04 +00:00
s_fmaf.c Do not include fenv_private.h in math_private.h. 2018-09-03 21:09:04 +00:00
s_fmul.c Add narrowing multiply functions. 2018-05-16 00:05:28 +00:00
s_fpclassify.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
s_frexp.c Use libm_alias_double for dbl-64 frexp. 2017-10-03 20:56:46 +00:00
s_fromfp_main.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
s_fromfp.c Use libm_alias_double for some dbl-64 functions. 2017-09-29 23:54:33 +00:00
s_fromfpx.c Use libm_alias_double for some dbl-64 functions. 2017-09-29 23:54:33 +00:00
s_fsub.c Add narrowing subtract functions. 2018-03-20 00:34:52 +00:00
s_getpayload.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
s_isinf.c Move LDBL_CLASSIFY_COMPAT to its own header. 2018-02-01 21:01:00 +00:00
s_isnan.c Move LDBL_CLASSIFY_COMPAT to its own header. 2018-02-01 21:01:00 +00:00
s_issignaling.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
s_llrint.c Move fenv.h soft-float inlines from fenv_private.h to include/fenv.h. 2018-09-04 19:52:06 +00:00
s_llround.c Move fenv.h soft-float inlines from fenv_private.h to include/fenv.h. 2018-09-04 19:52:06 +00:00
s_log1p.c Do not include math-barriers.h in math_private.h. 2018-05-11 15:11:38 +00:00
s_logb.c Use libm_alias_double for dbl-64 logb. 2017-10-03 23:44:41 +00:00
s_lrint.c Move fenv.h soft-float inlines from fenv_private.h to include/fenv.h. 2018-09-04 19:52:06 +00:00
s_lround.c Move fenv.h soft-float inlines from fenv_private.h to include/fenv.h. 2018-09-04 19:52:06 +00:00
s_modf.c Use libm_alias_double for dbl-64 modf. 2017-10-03 23:46:23 +00:00
s_nearbyint.c Do not include fenv_private.h in math_private.h. 2018-09-03 21:09:04 +00:00
s_nexttoward.c
s_nextup.c Move math_check_force_underflow macros to separate math-underflow.h. 2018-05-10 00:53:04 +00:00
s_remquo.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
s_rint.c Use libm_alias_double for more dbl-64 functions. 2017-10-03 17:47:35 +00:00
s_round.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
s_roundeven.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
s_scalbln.c [BZ #6803] Set errno for scalbln, scalbn 2014-06-20 07:48:20 +05:30
s_scalbn.c Make scalbn set errno (bug 6803). 2015-09-16 21:11:00 +00:00
s_setpayload_main.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
s_setpayload.c Use libm_alias_double for some dbl-64 functions. 2017-09-29 23:54:33 +00:00
s_setpayloadsig.c Use libm_alias_double for some dbl-64 functions. 2017-09-29 23:54:33 +00:00
s_signbit.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
s_sin.c Do not include fenv_private.h in math_private.h. 2018-09-03 21:09:04 +00:00
s_sincos.c Do not include fenv_private.h in math_private.h. 2018-09-03 21:09:04 +00:00
s_tan.c Do not include fenv_private.h in math_private.h. 2018-09-03 21:09:04 +00:00
s_tanh.c Move math_check_force_underflow macros to separate math-underflow.h. 2018-05-10 00:53:04 +00:00
s_totalorder.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
s_totalordermag.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
s_trunc.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
s_ufromfp.c Use libm_alias_double for some dbl-64 functions. 2017-09-29 23:54:33 +00:00
s_ufromfpx.c Use libm_alias_double for some dbl-64 functions. 2017-09-29 23:54:33 +00:00
sincos32.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
sincos32.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
sincostab.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
uasncs.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
uatan.tbl Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
upow.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
upow.tbl Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
urem.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
usncs.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
utan.h Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
utan.tbl Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
x2y2m1.c Do not include fenv_private.h in math_private.h. 2018-09-03 21:09:04 +00:00
x2y2m1f.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00