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Wilco Dijkstra c3d466cba1 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.
2018-02-12 10:47:09 +00:00
argp Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
assert Fix uninitialized variable in assert_perror (bug 22761) 2018-02-05 11:06:15 +01:00
benchtests Remove slow paths from pow 2018-02-12 10:47:09 +00:00
bits Post-cleanup 2: minimize _G_config.h. 2018-02-07 10:10:32 -05:00
catgets Update copyright dates not handled by scripts/update-copyrights. 2018-01-01 00:41:16 +00:00
ChangeLog.old Add missing reference to bug 21654 2017-10-07 13:14:36 +02:00
conform Don't install libio.h or _G_config.h. 2018-02-07 10:07:31 -05:00
crypt crypt: Fix badsalttest test (Bug 22765) 2018-02-01 00:02:49 -08:00
csu Post-cleanup 2: minimize _G_config.h. 2018-02-07 10:10:32 -05:00
ctype Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
debug Update copyright dates not handled by scripts/update-copyrights. 2018-01-01 00:41:16 +00:00
dirent Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
dlfcn Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
elf Add elf.h NT_* macros from Linux 4.15 (bug 14890). 2018-02-06 00:37:17 +00:00
gmon Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
gnulib Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
grp Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
gshadow Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
hesiod Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
hurd hurd: Fix preprocessor indentation 2018-01-29 23:00:17 +01:00
iconv Update copyright dates not handled by scripts/update-copyrights. 2018-01-01 00:41:16 +00:00
iconvdata Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
include Add build infrastructure for narrowing libm functions. 2018-02-09 21:18:52 +00:00
inet Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
intl Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
io Revert "hurd: Fix building io/tst-fchownat.c" 2018-01-28 19:13:20 +01:00
libidn Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
libio Post-cleanup 2: minimize _G_config.h. 2018-02-07 10:10:32 -05:00
locale Fix -Os strcoll, wcscoll, build (bug 21313). 2018-02-07 13:36:14 +00:00
localedata hr_HR: Add alternative month names (bug 10871). 2018-01-30 12:48:17 +01:00
login Update copyright dates not handled by scripts/update-copyrights. 2018-01-01 00:41:16 +00:00
mach hurd: Add expected ABI lists 2018-01-29 22:07:44 +01:00
malloc [BZ #22830] malloc_stats: restore cancellation for stderr correctly. 2018-02-10 16:24:17 -05:00
manual Remove slow paths from pow 2018-02-12 10:47:09 +00:00
math Remove slow paths from pow 2018-02-12 10:47:09 +00:00
mathvec Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
misc Fix -Os gnu_dev_* linknamespace, localplt issues (bug 15105, bug 19463). 2018-02-07 14:57:31 +00:00
nis libnsl: Turn remaining symbols into compat symbols [BZ #22701] 2018-01-29 17:42:30 +01:00
nptl Revert Intel CET changes to __jmp_buf_tag (Bug 22743) 2018-01-25 23:43:46 -08:00
nptl_db Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
nscd nscd: don't unconditionally use PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP 2018-02-11 18:22:11 +01:00
nss nss: Adjust tests to use nss_files only 2018-01-30 14:26:31 +01:00
po Update translations from the Translation Project 2018-01-17 22:00:50 +00:00
posix Define char16_t, char32_t consistently with uint_least16_t, uint_least32_t (bug 17979). 2018-02-07 20:33:55 +00:00
pwd Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
resolv hurd: fix warning 2018-01-27 16:43:16 +01:00
resource resource/tst-getrlimit.c: Add copyright header 2018-01-05 20:34:10 +01:00
rt Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
scripts Use MPFR 4.0.1 in build-many-glibcs.py. 2018-02-07 17:38:13 +00:00
setjmp Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
shadow Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
signal Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
socket Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
soft-fp Do not use packed structures in soft-fp. 2018-02-01 20:44:49 +00:00
stdio-common Remove some unnecessary redefinitions of std symbols. 2018-02-05 19:58:01 -05:00
stdlib hurd: Fix build 2018-02-04 14:02:36 +01:00
streams Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
string Unify and simplify bits/byteswap.h, bits/byteswap-16.h headers (bug 14508, bug 15512, bug 17082, bug 20530). 2018-02-06 21:55:08 +00:00
sunrpc Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
support support: Preserve errno in write_message, TEST_VERIFY and other checks 2018-01-12 13:35:01 +01:00
sysdeps Remove slow paths from pow 2018-02-12 10:47:09 +00:00
sysvipc Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
termios Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
time time: Reference CLOCKS_PER_SEC in clock comment [BZ #22735] 2018-02-02 11:59:31 +01:00
timezone Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
wcsmbs Define char16_t, char32_t consistently with uint_least16_t, uint_least32_t (bug 17979). 2018-02-07 20:33:55 +00:00
wctype Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
.gitattributes Assume __NR_openat is always defined 2016-03-23 23:35:08 +01:00
.gitignore Add *.pyc to .gitignore 2015-05-18 15:26:26 +05:30
abi-tags Remove the bulk of the NaCl port. 2017-05-20 08:09:10 -04:00
aclocal.m4 LIBC_SLIBDIR_RTLDDIR: substitute arguments in single quotes 2018-01-25 17:20:28 +01:00
ChangeLog Remove slow paths from pow 2018-02-12 10:47:09 +00:00
config.h.in Add RISC-V entries to config.h.in 2018-01-29 10:24:57 -08:00
config.make.in Pass -no-pie to GCC only if GCC defaults to PIE [BZ #22614] 2017-12-18 12:24:38 -08:00
configure Pass -no-pie to GCC only if GCC defaults to PIE [BZ #22614] 2017-12-18 12:24:38 -08:00
configure.ac Pass -no-pie to GCC only if GCC defaults to PIE [BZ #22614] 2017-12-18 12:24:38 -08:00
COPYING
COPYING.LIB
extra-lib.mk Rename cppflags-iterator.mk to libof-iterator.mk, remove extra-modules.mk. 2017-05-09 07:06:29 -04:00
gen-locales.mk
INSTALL Fix typo in the previous commit 2018-01-31 23:13:00 +00:00
libc-abis
libof-iterator.mk Rename cppflags-iterator.mk to libof-iterator.mk, remove extra-modules.mk. 2017-05-09 07:06:29 -04:00
LICENSES
MAINTAINERS Add MAINTAINERS 2017-05-11 13:38:30 -04:00
Makeconfig Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
Makefile Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
Makefile.in New make target to only build benchmark binaries 2016-04-20 10:23:28 +05:30
Makerules Allow make-link-multidir to make subdirectories 2018-01-06 23:35:46 -08:00
NEWS Add narrowing add functions. 2018-02-10 02:08:43 +00:00
o-iterator.mk
README Skeleton documentation for the RISC-V port 2018-01-29 10:22:26 -08:00
Rules Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
shlib-versions Extend NSS test suite 2017-07-17 15:52:44 -04:00
test-skeleton.c Update copyright dates with scripts/update-copyrights. 2018-01-01 00:32:25 +00:00
version.h Open master branch for glibc 2.28 development 2018-02-01 17:18:19 +00:00

This directory contains the sources of the GNU C Library.
See the file "version.h" for what release version you have.

The GNU C Library is the standard system C library for all GNU systems,
and is an important part of what makes up a GNU system.  It provides the
system API for all programs written in C and C-compatible languages such
as C++ and Objective C; the runtime facilities of other programming
languages use the C library to access the underlying operating system.

In GNU/Linux systems, the C library works with the Linux kernel to
implement the operating system behavior seen by user applications.
In GNU/Hurd systems, it works with a microkernel and Hurd servers.

The GNU C Library implements much of the POSIX.1 functionality in the
GNU/Hurd system, using configurations i[4567]86-*-gnu.  The current
GNU/Hurd support requires out-of-tree patches that will eventually be
incorporated into an official GNU C Library release.

When working with Linux kernels, this version of the GNU C Library
requires Linux kernel version 3.2 or later.

Also note that the shared version of the libgcc_s library must be
installed for the pthread library to work correctly.

The GNU C Library supports these configurations for using Linux kernels:

	aarch64*-*-linux-gnu
	alpha*-*-linux-gnu
	arm-*-linux-gnueabi
	hppa-*-linux-gnu
	i[4567]86-*-linux-gnu
	x86_64-*-linux-gnu	Can build either x86_64 or x32
	ia64-*-linux-gnu
	m68k-*-linux-gnu
	microblaze*-*-linux-gnu
	mips-*-linux-gnu
	mips64-*-linux-gnu
	powerpc-*-linux-gnu	Hardware or software floating point, BE only.
	powerpc64*-*-linux-gnu	Big-endian and little-endian.
	s390-*-linux-gnu
	s390x-*-linux-gnu
	riscv64-*-linux-gnu
	sh[34]-*-linux-gnu
	sparc*-*-linux-gnu
	sparc64*-*-linux-gnu
	tilegx-*-linux-gnu

If you are interested in doing a port, please contact the glibc
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See the file INSTALL to find out how to configure, build, and install
the GNU C Library.  You might also consider reading the WWW pages for
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