The existing implementations of lgamma functions (except for the ia64
versions) use the reflection formula for negative arguments. This
suffers large inaccuracy from cancellation near zeros of lgamma (near
where the gamma function is +/- 1).
This patch fixes this inaccuracy. For arguments above -2, there are
no zeros and no large cancellation, while for sufficiently large
negative arguments the zeros are so close to integers that even for
integers +/- 1ulp the log(gamma(1-x)) term dominates and cancellation
is not significant. Thus, it is only necessary to take special care
about cancellation for arguments around a limited number of zeros.
Accordingly, this patch uses precomputed tables of relevant zeros,
expressed as the sum of two floating-point values. The log of the
ratio of two sines can be computed accurately using log1p in cases
where log would lose accuracy. The log of the ratio of two gamma(1-x)
values can be computed using Stirling's approximation (the difference
between two values of that approximation to lgamma being computable
without computing the two values and then subtracting), with
appropriate adjustments (which don't reduce accuracy too much) in
cases where 1-x is too small to use Stirling's approximation directly.
In the interval from -3 to -2, using the ratios of sines and of
gamma(1-x) can still produce too much cancellation between those two
parts of the computation (and that interval is also the worst interval
for computing the ratio between gamma(1-x) values, which computation
becomes more accurate, while being less critical for the final result,
for larger 1-x). Because this can result in errors slightly above
those accepted in glibc, this interval is instead dealt with by
polynomial approximations. Separate polynomial approximations to
(|gamma(x)|-1)(x-n)/(x-x0) are used for each interval of length 1/8
from -3 to -2, where n (-3 or -2) is the nearest integer to the
1/8-interval and x0 is the zero of lgamma in the relevant half-integer
interval (-3 to -2.5 or -2.5 to -2).
Together, the two approaches are intended to give sufficient accuracy
for all negative arguments in the problem range. Outside that range,
the previous implementation continues to be used.
Tested for x86_64, x86, mips64 and powerpc. The mips64 and powerpc
testing shows up pre-existing problems for ldbl-128 and ldbl-128ibm
with large negative arguments giving spurious "invalid" exceptions
(exposed by newly added tests for cases this patch doesn't affect the
logic for); I'll address those problems separately.
[BZ #2542]
[BZ #2543]
[BZ #2558]
* sysdeps/ieee754/dbl-64/e_lgamma_r.c (__ieee754_lgamma_r): Call
__lgamma_neg for arguments from -28.0 to -2.0.
* sysdeps/ieee754/flt-32/e_lgammaf_r.c (__ieee754_lgammaf_r): Call
__lgamma_negf for arguments from -15.0 to -2.0.
* sysdeps/ieee754/ldbl-128/e_lgammal_r.c (__ieee754_lgammal_r):
Call __lgamma_negl for arguments from -48.0 or -50.0 to -2.0.
* sysdeps/ieee754/ldbl-96/e_lgammal_r.c (__ieee754_lgammal_r):
Call __lgamma_negl for arguments from -33.0 to -2.0.
* sysdeps/ieee754/dbl-64/lgamma_neg.c: New file.
* sysdeps/ieee754/dbl-64/lgamma_product.c: Likewise.
* sysdeps/ieee754/flt-32/lgamma_negf.c: Likewise.
* sysdeps/ieee754/flt-32/lgamma_productf.c: Likewise.
* sysdeps/ieee754/ldbl-128/lgamma_negl.c: Likewise.
* sysdeps/ieee754/ldbl-128/lgamma_productl.c: Likewise.
* sysdeps/ieee754/ldbl-128ibm/lgamma_negl.c: Likewise.
* sysdeps/ieee754/ldbl-128ibm/lgamma_productl.c: Likewise.
* sysdeps/ieee754/ldbl-96/lgamma_negl.c: Likewise.
* sysdeps/ieee754/ldbl-96/lgamma_product.c: Likewise.
* sysdeps/ieee754/ldbl-96/lgamma_productl.c: Likewise.
* sysdeps/generic/math_private.h (__lgamma_negf): New prototype.
(__lgamma_neg): Likewise.
(__lgamma_negl): Likewise.
(__lgamma_product): Likewise.
(__lgamma_productl): Likewise.
* math/Makefile (libm-calls): Add lgamma_neg and lgamma_product.
* math/auto-libm-test-in: Add more tests of lgamma.
* math/auto-libm-test-out: Regenerated.
* sysdeps/i386/fpu/libm-test-ulps: Update.
* sysdeps/x86_64/fpu/libm-test-ulps: Likewise.
Topic: strptime supports a %z input field descriptor, which parses a
time zone offset from UTC time into the broken-out time field tm_gmtoff.
Problems:
1) In the current implementation, the minutes portion calculation is
correct only for minutes evenly divisible by 3. This is because the
minutes value is converted to decimal time, but inadequate precision
leads to rounding which calculates results that are too low for
some values.
For example, due to rounding, a +1159 offset string results in an
incorrect tm_gmtoff of 43128 (== 11 * 3600 + 58.8 * 60) seconds,
instead of 43140 (== 11 * 3600 + 59 * 60) seconds. In contrast,
a +1157 offset (minutes divisible by 3) does not cause the bug,
and results in a correct tm_gmtoff of 43020.
2) strptime's %z specifier will not parse time offsets less than
-1200 or greater than +1200, or if only hour digits are present, less
than -12 or greater than +12. It will return NULL for offsets outside
that range. These limits do not meet historical and modern use cases:
* Present day exceeds the +1200 limit:
- Pacific/Auckland (New Zealand) summer time is +1300.
- Pacific/Kiritimati (Christmas Island) is +1400.
- Pacific/Apia (Samoa) summer time is +1400.
* Historical offsets exceeded +1500/-1500.
* POSIX supports -2459 to +2559.
* Offsets up to +/-9959 may occasionally be useful.
* Paul Eggert's notes provide additional detail:
- https://sourceware.org/ml/libc-alpha/2014-12/msg00068.html
- https://sourceware.org/ml/libc-alpha/2014-12/msg00072.html
3) tst-strptime2, part of the 'make check' test suite, does not test
for the above problems.
Corrective actions:
1) In time/strptime_l.c, calculate the offset from the hour and
minute portions directly, without the rounding errors introduced by
decimal time.
2) Remove the +/-1200 range limit, permitting strptime to parse offsets
from -9959 through +9959.
3) Add zone offset values to time/tst-strptime2.c.
* Test minutes evenly divisible by three (+1157) and not evenly
divisible by three (+1158 and +1159).
* Test offsets near the old and new range limits (-1201, -1330, -2459,
-2500, -99, -9959, +1201, +1330, +1400, +1401, +2559, +2600, +99,
and +9959)
The revised strptime passes all old and new tst-strptime2 tests.
This patch fixes the default wordsize-32 mmap implementation offset
calculation for negative values. Current code uses signed shift
operation to calculate the multiple size to use with syscall and
it is implementation defined. Change it to use a division base
on mmap page size (default being as before, 4096).
Tested on armv7hf.
[BZ #18877]
* posix/Makefile (tests): Add tst-mmap-offset.
* posix/tst-mmap.c: New file.
* sysdeps/unix/sysv/linux/generic/wordsize-32/mmap.c (__mmap): Fix
offset calculation for negative values.
This patch set introduces optimized string, wcsmbs and memory functions for
S390/S390x. The functions are accelerated by the usage of the new z13 vector
instructions.
The Principles of Operations manual for IBM z13 is publically available:
http://publibfi.boulder.ibm.com/epubs/pdf/dz9zr010.pdf
The support for these instructions in assembler was introduced by commits:
-"[Committed] S/390: Add support for IBM z13."
(https://sourceware.org/ml/binutils/2015-01/msg00197.html)
-"[Committed] S/390: Add more IBM z13 instructions"
(https://sourceware.org/ml/binutils/2015-03/msg00088.html)
The first patches do preparation for the latter optimization patches.
The floating point exception handling - fetestexcept(), ... - is fixed and
the platform and hwcap strings are extended.
The current ifunc routines memset, memcpy and memcmp are refactored and the
ifunc test-framework is now enabled.
A S390 specific configure-check tests if the used binutils supports the new
vector instructions. The optimized functions are provided via ifunc if the
binutils supports the vector instructions. Otherwise a message is dumped to
configure output and only the currently used common code functions are
available.
The optimized functions are implemented in common for s390-32 and s390-64
and the few differences are handled via #ifdef.
The ifunc-resolvers are defined in files sysdeps/s390/multiarch/<func>.c,
which choose either the current implementation __<func>_c() or the vector
implementation __<func>_vx() depending on the HWCAP_S390_VX flag bit in
AT_HWCAP field. If the bit is set, the hardware and the kernel are supporting
vector registers and instructions. If the used binutils lacks vector-support,
then the default implementation in string or wcsmbs directory is included
here instead.
The file sysdeps/s390/multiarch/<func>-c.c includes the current implementation
and defines the function name __<func>_c.
The assembler files sysdeps/s390/multiarch/<func>-vx.S with the vector
instructions are using the directive '.machine "z13"' to allow building glibc
without option '-march=z13'. Additionally the directive '.machinemode
"zarch_nohighgprs"' is needed for the 31bit glibc. This mode does not set the
highgprs flag in ELF header, which would lead to an unloadable libc on a 31bit
kernel.
The most optimized string functions are structured in the same way:
The first 16 bytes of the string is loaded unaligned via vlbb - vector load
to block boundary (e.g. 4k). This instruction loads 16 bytes if possible.
In case of a page cross, it only loads the last bytes of the current page
without a segmentation fault.
Afterwards these first part of string is processed. If e.g. for strlen the end
of string is reached within this first part, the function returns. Otherwise
the pointer is aligned to 16 byte, so i can load a full vector register with vl
without checking for a page cross. Afterwards the first part of string is
processed. If e.g. for strlen the end of string is reached within this first
part, the function returns. Otherwise the pointer is aligned to 16 byte, so
a full vector register can be loaded with vl - vector load - without checking
for a page cross. The remaining string is processed in a four times unrolled
loop, because benchmark results measured improvements compared to a non
unrolled loop.
The optimized wide string functions can only handle 4byte aligned string
pointers. Although a wchar_t pointer should always be 4byte aligned, the most
current common code wide string functions can handle non aligned strings.
Thus the optimized functions will fall back to the common code functions in
case of a non aligned wide string to behave the same as before this patch.
Some string tests can test the string and the wide string version of a function.
The remaining ones are extended and new wide string tests are added.
This is the same in case of the benchtests.
ChangeLog:
* NEWS: New item for IBM z13 string optimizations.
The csqrt implementations in glibc can miss underflow exceptions when
the real or imaginary part of the result becomes tiny in the course of
scaling down (in particular, multiplication by 0.5) and that scaling
is exact although the relevant part of the mathematical result isn't.
This patch forces the exception in a similar way to previous fixes.
Tested for x86_64 and x86.
[BZ #18370]
* math/s_csqrt.c (__csqrt): Force underflow exception for results
whose real or imaginary part has small absolute value.
* math/s_csqrtf.c (__csqrtf): Likewise.
* math/s_csqrtl.c (__csqrtl): Likewise.
* math/auto-libm-test-in: Add more tests of csqrt.
* math/auto-libm-test-out: Regenerated.
* sysdeps/i386/fpu/libm-test-ulps: Update.
lang_lib (which reflects ISO 639-2/B (bibliographic) codes) and
lang_term (which reflects ISO 639-2/T (terminology) codes) should be
identical except for those languages for which ISO 639-2 specifies
separate bibliographic/terminology values.
I used this Library of Congress page as the source:
http://www.loc.gov/standards/iso639-2/php/code_list.php
The csqrt functions scale up small arguments to avoid underflows when
calling hypot functions. However, even when hypot does not underflow,
a subsequent calculation of 0.5 * hypot can underflow. This patch
duly increases the threshold and scale factor to avoid such underflows
as well.
Tested for x86_64, x86 and mips64.
[BZ #18823]
* math/s_csqrt.c (__csqrt): Increase threshold and scale factor
for scaling up small arguments.
* math/s_csqrtf.c (__csqrtf): Likewise.
* math/s_csqrtl.c (__csqrtl): Likewise.
* math/auto-libm-test-in: Add more tests of csqrt.
* math/auto-libm-test-out: Regenerated.
I think the last clause of the conditional,
|| __n <= __bos (__dest)
may be backward. The code should call the runtime-checking function
if __n is not constant, or if __n is known to be LARGER than the size
of the destination.
Various fma implementations have logic that, when computing fma (x, y,
z) where z is large (so care needs taking to avoid internal overflow)
but x * y is small, scale x * y up instead of down to avoid internal
underflows resulting from scaling down. (In these cases, x * y is
small enough that only its sign actually matters rather than the exact
value.)
The threshold for scaling up instead of down was correct for "if the
unscaled values were multiplied, the low part of the multiplication
could underflow", and the scaling was sufficient to ensure that the
low part of the multiplication did not underflow (given that cases of
very small x * y - less than half the least subnormal - were
previously dealt with). However, the choice in the functions wasn't
between scaling up or no scaling, but between scaling up and scaling
down (scaling down actually being needed when x * y isn't so small
compared to z and so the exact value does matter). Thus a larger
threshold is needed to ensure that scaling down doesn't produce values
the multiplication of whose low parts underflows. This patch
increases the thresholds accordingly.
Tested for x86_64, x86 and mips64 (with the MIPS version of s_fmal.c
removed so that the ldbl-128 version gets tested instead of the
soft-fp one).
[BZ #18824]
* sysdeps/ieee754/dbl-64/s_fma.c (__fma): Increase threshold for
scaling x * y up instead of down.
* sysdeps/ieee754/ldbl-128/s_fmal.c (__fmal): Likewise.
* sysdeps/ieee754/ldbl-96/s_fmal.c (__fmal): Likewise.
* math/auto-libm-test-in: Add more tests of fma.
* math/auto-libm-test-out: Regenerated.
Similar to various other bugs in this area, some tanh implementations
do not raise the underflow exception for subnormal arguments, when the
result is tiny and inexact. This patch forces the exception in a
similar way to previous fixes.
Tested for x86_64, x86, mips64 and powerpc.
[BZ #16520]
* sysdeps/ieee754/dbl-64/s_tanh.c: Include <float.h>.
(__tanh): Force underflow exception for arguments with small
absolute value.
* sysdeps/ieee754/flt-32/s_tanhf.c: Include <float.h>.
(__tanhf): Force underflow exception for arguments with small
absolute value.
* sysdeps/ieee754/ldbl-128/s_tanhl.c: Include <float.h>.
(__tanhl): Force underflow exception for arguments with small
absolute value.
* sysdeps/ieee754/ldbl-128ibm/s_tanhl.c: Include <float.h>.
(__tanhl): Force underflow exception for arguments with small
absolute value.
* sysdeps/ieee754/ldbl-96/s_tanhl.c: Include <float.h>.
(__tanhl): Force underflow exception for arguments with small
absolute value.
* math/auto-libm-test-in: Add more tests of tanh.
* math/auto-libm-test-out: Regenerated.
* sysdeps/i386/fpu/libm-test-ulps: Update.
https://sourceware.org/bugzilla/show_bug.cgi?id=18778
If dlopen fails to load an object that has triggered loading libpthread it
causes ld.so to unload libpthread because its DF_1_NODELETE flags has been
forcefully cleared. The next call to __rtdl_unlock_lock_recursive will crash
since pthread_mutex_unlock no longer exists.
This patch moves l->l_flags_1 &= ~DF_1_NODELETE out of loop through all loaded
libraries and performs the action only on inconsistent one.
[BZ #18778]
* elf/Makefile (tests): Add Add tst-nodelete2.
(modules-names): Add tst-nodelete2mod.
(tst-nodelete2mod.so-no-z-defs): New.
($(objpfx)tst-nodelete2): Likewise.
($(objpfx)tst-nodelete2.out): Likewise.
(LDFLAGS-tst-nodelete2): Likewise.
* elf/dl-close.c (_dl_close_worker): Move DF_1_NODELETE clearing
out of loop through all loaded libraries.
* elf/tst-nodelete2.c: New file.
* elf/tst-nodelete2mod.c: Likewise.
ldbl-128ibm tanhl uses a too-small threshold to decide when to return
+/-1, resulting in large errors. This patch changes it to a more
appropriate threshold (the requirement is for 2*exp(-2|x|) to be small
in terms of ulps of 1).
Tested for x86_64, x86 and powerpc.
[BZ #18790]
* sysdeps/ieee754/ldbl-128ibm/s_tanhl.c (__tanhl): Increase
threshold for returning +/- 1.
* math/auto-libm-test-in: Add more tests of tanh.
* math/auto-libm-test-out: Regenerated.
* sysdeps/i386/fpu/libm-test-ulps: Update.
ldbl-128ibm sinhl uses a too-big threshold to decide when to return
the argument, resulting in large errors. This patch fixes it to use a
more appropriate threshold.
Tested for x86_64, x86 and powerpc.
[BZ #18789]
* sysdeps/ieee754/ldbl-128ibm/e_sinhl.c (__ieee754_sinhl): Use
smaller threshold for returning the argument.
* math/auto-libm-test-in: Add more tests of sinh.
* math/auto-libm-test-out: Regenerated.
* sysdeps/i386/fpu/libm-test-ulps: Update.
The attached change fixes the miscompilation of sched_setaffinity() on
hppa. This is an old problem that was fixed on other architectures using
a similar approach to the attached change. See:
https://sourceware.org/ml/libc-hacker/2004-04/msg00016.html
Build tested on trunk. Patch has been applied to debian glibc for some time.
As noted in the bug, the asm operands need to be copied to register
variables to avoid operand reloads in the principal asm of the macro.
See the arm implementation for reference. Otherwise we get:
../sysdeps/unix/sysv/linux/hppa/bits/atomic.h:68:6: error:
can't find a register in class 'R1_REGS' while reloading 'asm'
Build tested on trunk with gcc-4.8. Similar patch has been tested
with 2.19 on Debian hppa-unknown-linux-gnu.
Similar to various other bugs in this area, some tan implementations
do not raise the underflow exception for subnormal arguments, when the
result is tiny and inexact. This patch forces the exception in a
similar way to previous fixes.
Tested for x86_64, x86, mips64 and powerpc.
[BZ #16517]
* sysdeps/ieee754/dbl-64/s_tan.c: Include <float.h>.
(tan): Force underflow exception for arguments with small absolute
value.
* sysdeps/ieee754/flt-32/k_tanf.c: Include <float.h>.
(__kernel_tanf): Force underflow exception for arguments with
small absolute value.
* sysdeps/ieee754/ldbl-128/k_tanl.c: Include <float.h>.
(__kernel_tanl): Force underflow exception for arguments with
small absolute value.
* sysdeps/ieee754/ldbl-128ibm/k_tanl.c: Include <float.h>.
(__kernel_tanl): Force underflow exception for arguments with
small absolute value.
* sysdeps/ieee754/ldbl-96/k_tanl.c: Include <float.h>.
(__kernel_tanl): Force underflow exception for arguments with
small absolute value.
* math/auto-libm-test-in: Add more tests of tan.
* math/auto-libm-test-out: Regenerated.
Similar to various other bugs in this area, some sinh implementations
do not raise the underflow exception for subnormal arguments, when the
result is tiny and inexact. This patch forces the exception in a
similar way to previous fixes.
Tested for x86_64, x86, mips64 and powerpc.
[BZ #16519]
* sysdeps/ieee754/dbl-64/e_sinh.c: Include <float.h>.
(__ieee754_sinh): Force underflow exception for arguments with
small absolute value.
* sysdeps/ieee754/flt-32/e_sinhf.c: Include <float.h>.
(__ieee754_sinhf): Force underflow exception for arguments with
small absolute value.
* sysdeps/ieee754/ldbl-128/e_sinhl.c: Include <float.h>.
(__ieee754_sinhl): Force underflow exception for arguments with
small absolute value.
* sysdeps/ieee754/ldbl-128ibm/e_sinhl.c: Include <float.h>.
(__ieee754_sinhl): Force underflow exception for arguments with
small absolute value.
* sysdeps/ieee754/ldbl-96/e_sinhl.c: Include <float.h>.
(__ieee754_sinhl): Force underflow exception for arguments with
small absolute value.
* math/auto-libm-test-in: Add more tests of sinh.
* math/auto-libm-test-out: Regenerated.
* sysdeps/i386/fpu/libm-test-ulps: Update.
In the "Kill regexp.h" thread, Joseph dug up more accurate information
about exactly which editions of the Single Unix Standard included and
deprecated this header.
The flt-32 implementation of powf wrongly uses x-1 instead of |x|-1
when computing log (x) for the case where |x| is close to 1 and y is
large. This patch fixes the logic accordingly. Relevant tests
existed for x close to 1, and corresponding tests are added for x
close to -1, as well as for some new variant cases.
Tested for x86_64 and x86.
[BZ #18647]
* sysdeps/ieee754/flt-32/e_powf.c (__ieee754_powf): For large y
and |x| close to 1, use absolute value of x when computing log.
* math/auto-libm-test-in: Add more tests of pow.
* math/auto-libm-test-out: Regenerated.
as discussed in the thread starting at
https://sourceware.org/ml/libc-alpha/2015-06/msg00098.html
it looks like the best options is to remove locale timezone information
from locales which currently provide it (in incomplete or incorrect
fashion) rather than to start duplicating tzdata info in glibc.
This patch adds __nonnull annotations for wcscat, wcsncat, wcscmp and wcsncmp.
These added annotations match the annoations for strcat, strncat, strcmp, strncmp in glibc.
