glibc/sysdeps/x86_64
Joseph Myers a5721ebc68 Fix clog, clog10 inaccuracy (bug 19016).
For arguments with X^2 + Y^2 close to 1, clog and clog10 avoid large
errors from log(hypot) by computing X^2 + Y^2 - 1 in a way that avoids
cancellation error and then using log1p.

However, the thresholds for using that approach still result in log
being used on argument as large as sqrt(13/16) > 0.9, leading to
significant errors, in some cases above the 9ulp maximum allowed in
glibc libm.  This patch arranges for the approach using log1p to be
used in any cases where |X|, |Y| < 1 and X^2 + Y^2 >= 0.5 (with the
existing allowance for cases where one of X and Y is very small),
adjusting the __x2y2m1 functions to work with the wider range of
inputs.  This way, log only gets used on arguments below sqrt(1/2) (or
substantially above 1), where the error involved is much less.

Tested for x86_64, x86, mips64 and powerpc.  For the ulps regeneration
I removed the existing clog and clog10 ulps before regenerating to
allow any reduced ulps to appear.  Tests added include those found by
random test generation to produce large ulps either before or after
the patch, and some found by trying inputs close to the (0.75, 0.5)
threshold where the potential errors from using log are largest.

	[BZ #19016]
	* sysdeps/generic/math_private.h (__x2y2m1f): Update comment to
	allow more cases with X^2 + Y^2 >= 0.5.
	* sysdeps/ieee754/dbl-64/x2y2m1.c (__x2y2m1): Likewise.  Add -1 as
	normal element in sum instead of special-casing based on values of
	arguments.
	* sysdeps/ieee754/dbl-64/x2y2m1f.c (__x2y2m1f): Update comment.
	* sysdeps/ieee754/ldbl-128/x2y2m1l.c (__x2y2m1l): Likewise.  Add
	-1 as normal element in sum instead of special-casing based on
	values of arguments.
	* sysdeps/ieee754/ldbl-128ibm/x2y2m1l.c (__x2y2m1l): Likewise.
	* sysdeps/ieee754/ldbl-96/x2y2m1.c [FLT_EVAL_METHOD != 0]
	(__x2y2m1): Update comment.
	* sysdeps/ieee754/ldbl-96/x2y2m1l.c (__x2y2m1l): Likewise.  Add -1
	as normal element in sum instead of special-casing based on values
	of arguments.
	* math/s_clog.c (__clog): Handle more cases using log1p without
	hypot.
	* math/s_clog10.c (__clog10): Likewise.
	* math/s_clog10f.c (__clog10f): Likewise.
	* math/s_clog10l.c (__clog10l): Likewise.
	* math/s_clogf.c (__clogf): Likewise.
	* math/s_clogl.c (__clogl): Likewise.
	* math/auto-libm-test-in: Add more tests of clog and clog10.
	* math/auto-libm-test-out: Regenerated.
	* sysdeps/i386/fpu/libm-test-ulps: Update.
	* sysdeps/x86_64/fpu/libm-test-ulps: Likewise.
2015-09-28 22:11:22 +00:00
..
64 Move architecture shlib-versions files to Linux-specific directories. 2014-07-17 14:31:12 +00:00
fpu Fix clog, clog10 inaccuracy (bug 19016). 2015-09-28 22:11:22 +00:00
multiarch Remove x86-64 rtld-xxx.c and rtld-xxx.S 2015-08-25 08:50:06 -07:00
nptl Save and restore vector registers in x86-64 ld.so 2015-08-25 04:34:13 -07:00
x32 lround: provide cast for wordsize-64 version if needed 2015-01-05 11:59:32 -05:00
____longjmp_chk.S ____longjmp_chk is now OS-specific. 2009-07-30 21:42:27 -07:00
__longjmp.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
_mcount.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
abort-instr.h Update. 2001-09-19 10:37:31 +00:00
add_n.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
addmul_1.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
atomic-machine.h Move bits/atomic.h to atomic-machine.h (bug 14912). 2015-09-11 20:00:19 +00:00
backtrace.c Move bits/libc-lock.h and bits/libc-lockP.h out of bits/ (bug 14912). 2015-09-08 21:11:03 +00:00
bsd-_setjmp.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
bsd-setjmp.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
bzero.S Make an empty file. 2007-10-16 05:59:15 +00:00
cacheinfo.c Move x86_64 init-arch.h to sysdeps/x86/init-arch.h 2015-08-20 04:29:23 -07:00
configure More strict check of AVX512 support in assembler. 2015-06-11 13:50:07 +03:00
configure.ac More strict check of AVX512 support in assembler. 2015-06-11 13:50:07 +03:00
crti.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
crtn.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
dl-irel.h Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
dl-lookupcfg.h Add ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA to x86 2015-03-31 05:16:57 -07:00
dl-machine.h Save and restore vector registers in x86-64 ld.so 2015-08-25 04:34:13 -07:00
dl-procinfo.c Add _dl_x86_cpu_features to rtld_global 2015-08-13 03:41:22 -07:00
dl-runtime.c * elf/dl-runtime.c (reloc_offset): Define. 2009-03-15 00:26:14 +00:00
dl-tls.h Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
dl-tlsdesc.h Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
dl-tlsdesc.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
dl-trampoline.h Save and restore vector registers in x86-64 ld.so 2015-08-25 04:34:13 -07:00
dl-trampoline.S Save and restore vector registers in x86-64 ld.so 2015-08-25 04:34:13 -07:00
ffs.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
ffsll.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
hp-timing.h Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
htonl.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
ifuncmain8.c Save and restore vector registers in x86-64 ld.so 2015-08-25 04:34:13 -07:00
ifuncmod8.c Save and restore vector registers in x86-64 ld.so 2015-08-25 04:34:13 -07:00
Implies Use x86-64 bits/byteswap.h for both i386 and x86_64 2012-05-30 14:13:18 -07:00
jmpbuf-offsets.h Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
jmpbuf-unwind.h Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
l10nflist.c Minor optimization of popcount in l10nflist 2011-08-11 14:07:04 -04:00
ldbl2mpn.c [BZ #4586] 2007-06-08 02:50:59 +00:00
ldsodefs.h Add _dl_x86_cpu_features to rtld_global 2015-08-13 03:41:22 -07:00
link-defines.sym Replace __int128 with __int128_t 2014-05-30 10:50:21 -07:00
locale-defines.sym Implement optimized strcaecmp for x86-64. 2010-07-30 00:14:04 -07:00
localplt.data Extend local PLT reference check 2015-07-29 11:58:06 -07:00
lshift.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
machine-gmon.h Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
Makefile Don't disable SSE in x86-64 ld.so 2015-08-26 07:55:42 -07:00
memchr.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
memcmp.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
memcpy_chk.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
memcpy.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
memmove.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
mempcpy_chk.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
mempcpy.S Remove bounded-pointers handling from x86_64 assembly sources. 2013-02-17 21:57:26 +00:00
memrchr.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
memset_chk.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
memset.S Replace %xmm8 with %xmm0 2015-08-25 08:48:34 -07:00
memusage.h Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
mp_clz_tab.c * sysdeps/x86_64/mp_clz_tab.c: New file. 2009-04-15 04:30:41 +00:00
mul_1.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
preconfigure rename configure.in to configure.ac 2013-10-30 17:32:08 +10:00
preconfigure.ac rename configure.in to configure.ac 2013-10-30 17:32:08 +10:00
rawmemchr.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
rshift.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
sched_cpucount.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
setjmp.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
stack-aliasing.h Clean up stack-coloring macros. 2014-06-20 19:50:16 -07:00
stackguard-macros.h BZ #15754: CVE-2013-4788 2013-09-23 00:52:09 -04:00
stackinfo.h Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
start.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
stpcpy.S Update. 2004-05-28 06:56:51 +00:00
strcasecmp_l-nonascii.c Remove pre-ISO C support 2012-01-07 23:57:22 -05:00
strcasecmp_l.S Implement optimized strcaecmp for x86-64. 2010-07-30 00:14:04 -07:00
strcasecmp.S Implement optimized strcaecmp for x86-64. 2010-07-30 00:14:04 -07:00
strcat.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
strchr.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
strchrnul.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
strcmp.S Use SSE2 optimized strcmp in x86-64 ld.so 2015-08-25 12:38:11 -07:00
strcpy.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
strcspn.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
strlen.S Replace %xmm[8-12] with %xmm[0-4] 2015-08-25 08:51:23 -07:00
strncase_l-nonascii.c Remove pre-ISO C support 2012-01-07 23:57:22 -05:00
strncase_l.S Add optimized strncasecmp versions for x86-64. 2010-08-14 22:04:01 -07:00
strncase.S Add optimized strncasecmp versions for x86-64. 2010-08-14 22:04:01 -07:00
strncmp.S Add SSE2 support to str{,n}cmp for x86-64. 2009-07-26 13:32:28 -07:00
strnlen.S Faster strlen on x64. 2013-03-18 07:39:12 +01:00
strpbrk.S Update. 2002-08-31 17:45:33 +00:00
strrchr.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
strspn.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
strtok_r.S Remove bounded-pointers handling from x86_64 assembly sources. 2013-02-17 21:57:26 +00:00
strtok.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
sub_n.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
submul_1.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
sysdep.h Start of series of patches with x86_64 vector math functions. 2015-06-09 14:25:49 +03:00
tls-macros.h Split tls-macros.h into sysdeps directories. 2012-07-17 11:30:58 +00:00
tlsdesc.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
tlsdesc.sym Introduce TLS descriptors for i386 and x86_64. 2008-05-13 05:41:30 +00:00
tst-audit3.c Modify several tests to use test-skeleton.c 2014-11-05 15:24:08 +05:30
tst-audit4.c Modify several tests to use test-skeleton.c 2014-11-05 15:24:08 +05:30
tst-audit5.c Modify several tests to use test-skeleton.c 2014-11-05 15:24:08 +05:30
tst-audit6.c Modify several tests to use test-skeleton.c 2015-07-15 15:10:23 +05:30
tst-audit7.c Move x86_64-specific audit tests to sysdeps/x86_64/. 2013-04-25 19:23:11 +00:00
tst-audit10.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
tst-audit.h Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
tst-auditmod3a.c Move x86_64-specific audit tests to sysdeps/x86_64/. 2013-04-25 19:23:11 +00:00
tst-auditmod3b.c Move x86_64-specific audit tests to sysdeps/x86_64/. 2013-04-25 19:23:11 +00:00
tst-auditmod4a.c Move x86_64-specific audit tests to sysdeps/x86_64/. 2013-04-25 19:23:11 +00:00
tst-auditmod4b.c Add la_symbind32 to x86-64 audit tests 2015-07-07 06:09:29 -07:00
tst-auditmod5a.c Move x86_64-specific audit tests to sysdeps/x86_64/. 2013-04-25 19:23:11 +00:00
tst-auditmod5b.c Add la_symbind32 to x86-64 audit tests 2015-07-07 06:09:29 -07:00
tst-auditmod6a.c Move x86_64-specific audit tests to sysdeps/x86_64/. 2013-04-25 19:23:11 +00:00
tst-auditmod6b.c Add la_symbind32 to x86-64 audit tests 2015-07-07 06:09:29 -07:00
tst-auditmod6c.c Add la_symbind32 to x86-64 audit tests 2015-07-07 06:09:29 -07:00
tst-auditmod7a.c Move x86_64-specific audit tests to sysdeps/x86_64/. 2013-04-25 19:23:11 +00:00
tst-auditmod7b.c Add la_symbind32 to x86-64 audit tests 2015-07-07 06:09:29 -07:00
tst-auditmod10a.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
tst-auditmod10b.c Add la_symbind32 to x86-64 audit tests 2015-07-07 06:09:29 -07:00
tst-mallocalign1.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
tst-quad1.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
tst-quad1pie.c Handle R_X86_64_RELATIVE64 and R_X86_64_64 for x32 2012-05-10 17:05:06 -07:00
tst-quad2.c Handle R_X86_64_RELATIVE64 and R_X86_64_64 for x32 2012-05-10 17:05:06 -07:00
tst-quad2pie.c Handle R_X86_64_RELATIVE64 and R_X86_64_64 for x32 2012-05-10 17:05:06 -07:00
tst-quadmod1.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
tst-quadmod1pie.S Handle R_X86_64_RELATIVE64 and R_X86_64_64 for x32 2012-05-10 17:05:06 -07:00
tst-quadmod2.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
tst-quadmod2pie.S Handle R_X86_64_RELATIVE64 and R_X86_64_64 for x32 2012-05-10 17:05:06 -07:00
tst-split-dynreloc.c Fix dynamic linker issue with bind-now 2015-08-19 05:37:01 -07:00
tst-split-dynreloc.lds Fix dynamic linker issue with bind-now 2015-08-19 05:37:01 -07:00
tst-stack-align.h Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
Versions Work around old buggy program which cannot cope with memcpy semantics. 2011-04-01 19:38:21 -04:00
wcschr.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
wcscmp.S Fix regcomp wcscoll, wcscmp namespace (bug 18497). 2015-06-09 21:07:30 +00:00
wcslen.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
wcsrchr.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00