The choice between the kill vs tgkill system calls is not just about
the TID reuse race, but also about whether the signal is sent to the
whole process (and any thread in it) or to a specific thread.
This was caught by the openposix test suite:
LTP: openposix test suite - FAIL: SIGUSR1 is member of new thread pendingset.
<https://gitlab.com/cki-project/kernel-tests/-/issues/764>
Fixes commit 526c3cf11e ("nptl: Fix race
between pthread_kill and thread exit (bug 12889)").
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Some kernel versions (observed with kernel 5.14 and earlier) can list
"0" entries in /proc/self/task. This happens when a thread exits
while the task list is being constructed. Treat this entry as not
present, like the proposed kernel patch does:
[PATCH] procfs: Do not list TID 0 in /proc/<pid>/task
<https://lore.kernel.org/all/8735pn5dx7.fsf@oldenburg.str.redhat.com/>
Fixes commit 032d74eaf6 ("support: Add
support_wait_for_thread_exit").
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Linux added FUTEX_LOCK_PI2 to support clock selection
(commit bf22a6976897977b0a3f1aeba6823c959fc4fdae). With the new
flag we can now proper support CLOCK_MONOTONIC for
pthread_mutex_clocklock with Priority Inheritance. If kernel
does not support, EINVAL is returned instead.
The difference is the futex operation will be issued and the kernel
will advertise the missing support (instead of hard-code error
return).
Checked on x86_64-linux-gnu and i686-linux-gnu on Linux 5.14, 5.11,
and 4.15.
This patch uses the new futex PI operation provided by Linux v5.14
when it is required.
The futex_lock_pi64() is moved to futex-internal.c (since it used on
two different places and its code size might be large depending of the
kernel configuration) and clockid is added as an argument.
Co-authored-by: Kurt Kanzenbach <kurt@linutronix.de>
Linux v5.14.0 introduced a new futex operation called FUTEX_LOCK_PI2.
This kernel feature can be used to implement
pthread_mutex_clocklock(MONOTONIC)/PI.
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
C2X adds a macro _PRINTF_NAN_LEN_MAX to <stdio.h>, giving the maximum
length of printf output for a NaN. glibc never includes an
n-char-sequence in its printf output for NaNs, so the correct value
for glibc is 4 ("-nan" or "-NAN"); define the macro accordingly.
This patch makes the macro definition conditional on __GLIBC_USE
(ISOC2X), as is generally done with features from new standard
versions. The name is in the implementation namespace for older
standards, so it would also be possible to define it unconditionally.
Tested for x86_64.
glibc has had exp10 functions since long before they were
standardized; now they are standardized in TS 18661-4 and C2X, they
are also specified there to have a corresponding type-generic macro.
Add one to <tgmath.h>, so fixing bug 26108.
glibc doesn't have other functions from TS 18661-4 yet, but when
added, it will be natural to add the type-generic macro for each
function family at the same time as the functions.
Tested for x86_64.
commit ec935dea63
Author: Florian Weimer <fweimer@redhat.com>
Date: Fri Apr 24 22:31:15 2020 +0200
elf: Implement __libc_early_init
has
@@ -856,6 +876,11 @@ no more namespaces available for dlmopen()"));
/* See if an error occurred during loading. */
if (__glibc_unlikely (exception.errstring != NULL))
{
+ /* Avoid keeping around a dangling reference to the libc.so link
+ map in case it has been cached in libc_map. */
+ if (!args.libc_already_loaded)
+ GL(dl_ns)[nsid].libc_map = NULL;
+
do_dlopen calls _dl_open with nsid == __LM_ID_CALLER (-2), which calls
dl_open_worker with args.nsid = nsid. dl_open_worker updates args.nsid
if it is __LM_ID_CALLER. After dl_open_worker returns, it is wrong to
use nsid.
Replace nsid with args.nsid after dl_open_worker returns. This fixes
BZ #27609.
GCC treats the pragma as a statement, so that the else branch only
consists of the pragma, not the return statement.
Fixes commit a725ff1de9 ("Suppress
-Wcast-qual warnings in bsearch").
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
The first cast to (void *) is redundant but should be (const void *)
anyway, because that's the type of the lvalue being assigned to.
The second cast is necessary and intentionally not const-correct, so
tell the compiler not to warn about it.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
When add ld.so to a new namespace, we don't actually load ld.so. We
create a new link map and refers the real one for almost everything.
Copy l_addr and l_ld from the real ld.so link map to avoid GDB warning:
warning: .dynamic section for ".../elf/ld-linux-x86-64.so.2" is not at the expected address (wrong library or version mismatch?)
when handling shared library loaded by dlmopen.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Recent versions of binutils (with commit
b25f942e18d6ecd7ec3e2d2e9930eb4f996c258a) stopped preserving "sticky"
options across a base `.machine` directive, nullifying the use of
passing "-many" through GCC to the assembler. As a result, some
instructions which were recognized even under older, more stringent
`.machine` directives become unrecognized instructions in that
context.
In `sysdeps/powerpc/tst-set_ppr.c`, the use of the `mfppr32` extended
mnemonic became unrecognized, as the default compilation with GCC for
32bit powerpc adds a `.machine ppc` in the resulting assembly, so the
command line option `-Wa,-many` is essentially ignored, and the ISA 2.06
instructions and mnemonics, like `mfppr32`, are unrecognized.
The compilation of `sysdeps/powerpc/tst-set_ppr.c` fails with:
Error: unrecognized opcode: `mfppr32'
Add appropriate `.machine` directives in the assembly to bracket the
`mfppr32` instruction.
Part of a 2019 fix (commit 9250e6610f) to
the above test's Makefile to add `-many` to the compilation when GCC
itself stopped passing `-many` to the assember no longer has any effect,
so remove that.
Reported-by: Joseph Myers <joseph@codesourcery.com>
At the last WG14 meeting,
<http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2711.htm> was
accepted, which places more emphasis on the new fmaximum / fminimum
functions and less on the old fmax / fmin functions. Some of the
changes are to examples, notes or otherwise don't require
implementation changes. However, the changes include removing the
_FloatN / _FloatNx versions of the fmax and fmin functions that came
from TS 18661-3.
Thus, those function versions should only be declared under similar
conditions to the _FloatN / _FloatNx versions of fmaxmag and fminmag:
for _GNU_SOURCE and pre-C2X use of __STDC_WANT_IEC_60559_TYPES_EXT__,
but not for C2X without _GNU_SOURCE.
In turn this requires a tgmath.h change so that the corresponding
tgmath.h macros, for C2X with __STDC_WANT_IEC_60559_TYPES_EXT__ but
without _GNU_SOURCE, don't try to use function variants that aren't
declared. (That issue doesn't arise for the tgmath.h macros for
fmaxmag and fminmag, because those aren't defined at all in those
circumstances unless __STDC_WANT_IEC_60559_BFP_EXT__ (from TS 18661-1
and not specified at all by C2X) is also defined, and in that case the
_FloatN / _FloatNx versions of fmaxmag and fminmag get declared - this
is only ever an issue when it's possible for some functions
corresponding to a type-generic-macro to be declared, and for _FloatN
/ _FloatNx functions in general to be declared, but without the
_FloatN / _FloatNx functions corresponding to that particular macro
being declared.)
Tested for x86_64.
C2X does not include fmaxmag and fminmag. When I updated feature test
macro handling accordingly (commit
858045ad1c, "Update floating-point
feature test macro handling for C2X", included in 2.34), I missed
updating tgmath.h so it doesn't define the corresponding type-generic
macros unless __STDC_WANT_IEC_60559_BFP_EXT__ is defined; I've now
reported this as bug 28397. Adjust the conditionals in tgmath.h
accordingly.
Tested for x86_64.
C2X adds new <math.h> functions for floating-point maximum and
minimum, corresponding to the new operations that were added in IEEE
754-2019 because of concerns about the old operations not being
associative in the presence of signaling NaNs. fmaximum and fminimum
handle NaNs like most <math.h> functions (any NaN argument means the
result is a quiet NaN). fmaximum_num and fminimum_num handle both
quiet and signaling NaNs the way fmax and fmin handle quiet NaNs (if
one argument is a number and the other is a NaN, return the number),
but still raise "invalid" for a signaling NaN argument, making them
exceptions to the normal rule that a function with a floating-point
result raising "invalid" also returns a quiet NaN. fmaximum_mag,
fminimum_mag, fmaximum_mag_num and fminimum_mag_num are corresponding
functions returning the argument with greatest or least absolute
value. All these functions also treat +0 as greater than -0. There
are also corresponding <tgmath.h> type-generic macros.
Add these functions to glibc. The implementations use type-generic
templates based on those for fmax, fmin, fmaxmag and fminmag, and test
inputs are based on those for those functions with appropriate
adjustments to the expected results. The RISC-V maintainers might
wish to add optimized versions of fmaximum_num and fminimum_num (for
float and double), since RISC-V (F extension version 2.2 and later)
provides instructions corresponding to those functions - though it
might be at least as useful to add architecture-independent built-in
functions to GCC and teach the RISC-V back end to expand those
functions inline, which is what you generally want for functions that
can be implemented with a single instruction.
Tested for x86_64 and x86, and with build-many-glibcs.py.
AF_NETLINK support is not quite optional on modern Linux systems
anymore, so it is likely that the first attempt will always succeed.
Consequently, there is no need to cache the result. Keep AF_UNIX
and the Internet address families as a fallback, for the rare case
that AF_NETLINK is missing. The other address families previously
probed are totally obsolete be now, so remove them.
Use this simplified version as the generic implementation, disabling
Netlink support as needed.
When running this test on the OpenRISC port I am working on this test
fails with a timeout. The test passes when being straced or debugged.
Looking at the code there seems to be a race condition in that:
1 main thread: calls xpthread_cancel
2 sub thread : receives cancel signal
3 sub thread : cleanup routine waits on barrier
4 main thread: re-inits barrier
5 main thread: waits on barrier
After getting to 5 the main thread and sub thread wait forever as the 2
barriers are no longer the same.
Removing the barrier re-init seems to fix this issue. Also, the barrier
does not need to be reinitialized as that is done by default.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Although it provide an alternate implementation that communicates
using pipe() instead of shared memory, no port uses and it adds extra
burden for posix_spawn() extensions.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
The use of sched_getaffinity on get_nproc and
sysconf (_SC_NPROCESSORS_ONLN) done in 903bc7dcc2 (BZ #27645)
breaks the top command in common hypervisor configurations and also
other monitoring tools.
The main issue using sched_getaffinity changed the symbols semantic
from system-wide scope of online CPUs to per-process one (which can
be changed with kernel cpusets or book parameters in VM).
This patch reverts mostly of the 903bc7dcc2, with the
exceptions:
* No more cached values and atomic updates, since they are inherent
racy.
* No /proc/cpuinfo fallback, since /proc/stat is already used and
it would require to revert more arch-specific code.
* The alloca is replace with a static buffer of 1024 bytes.
So the implementation first consult the sysfs, and fallbacks to procfs.
Checked on x86_64-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
This patch simplifies the memory allocation code and uses the sched
routines instead of reimplement it. This still uses a stack
allocation buffer, so it can be used on malloc initialization code.
Linux currently supports at maximum of 4096 cpus for most architectures:
$ find -iname Kconfig | xargs git grep -A10 -w NR_CPUS | grep -w range
arch/alpha/Kconfig- range 2 32
arch/arc/Kconfig- range 2 4096
arch/arm/Kconfig- range 2 16 if DEBUG_KMAP_LOCAL
arch/arm/Kconfig- range 2 32 if !DEBUG_KMAP_LOCAL
arch/arm64/Kconfig- range 2 4096
arch/csky/Kconfig- range 2 32
arch/hexagon/Kconfig- range 2 6 if SMP
arch/ia64/Kconfig- range 2 4096
arch/mips/Kconfig- range 2 256
arch/openrisc/Kconfig- range 2 32
arch/parisc/Kconfig- range 2 32
arch/riscv/Kconfig- range 2 32
arch/s390/Kconfig- range 2 512
arch/sh/Kconfig- range 2 32
arch/sparc/Kconfig- range 2 32 if SPARC32
arch/sparc/Kconfig- range 2 4096 if SPARC64
arch/um/Kconfig- range 1 1
arch/x86/Kconfig-# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
arch/x86/Kconfig- range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
arch/xtensa/Kconfig- range 2 32
With x86 supporting 8192:
arch/x86/Kconfig
976 config NR_CPUS_RANGE_END
977 int
978 depends on X86_64
979 default 8192 if SMP && CPUMASK_OFFSTACK
980 default 512 if SMP && !CPUMASK_OFFSTACK
981 default 1 if !SMP
So using a maximum of 32k cpu should cover all cases (and I would
expect once we start to have many more CPUs that Linux would provide
a more straightforward way to query for such information).
A test is added to check if sched_getaffinity can successfully return
with large buffers.
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
This is an internal function meant to return the number of avaliable
processor where the process can scheduled, different than the
__get_nprocs which returns a the system available online CPU.
The Linux implementation currently only calls __get_nprocs(), which
in tuns calls sched_getaffinity.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
d482ebfa67 ('htl: Keep thread signals blocked during its initialization')
fixed not letting signals get delivered too early during thread creation,
but it also affected the main thread, thus making it block signals by
default. We need to just let the main thread sigset as it is.
Add tst-ro-dynamic-mod to modules-names-nobuild to avoid
../Makerules:767: warning: ignoring old recipe for target '.../elf/tst-ro-dynamic-mod.so'
This updates BZ #28340 fix.
No bug. Remove reallocation of bufs between implementation tests. Move
initialization outside of foreach implementation test loop. Increase
iteration count.
Generally before this commit was seeing a great deal of variability
between runs. The goal of this commit is to make the results more
reliable.
Benchtests build and bench-memcmp succeeding.
Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
TS 18661-1 and C2X specify predefined macros __STDC_IEC_60559_BFP__
and __STDC_IEC_60559_COMPLEX__, making __STDC_IEC_559__ and
__STDC_IEC_559_COMPLEX__ obsolescent (but still included in the
standard). Now that we have all the functions from TS 18661-1, define
these macros in stdc-predef.h, under the same conditions in which the
older macros are defined, since support for the floating-point
features in TS 18661-1 is now at the same level as that for those in
C11 and before (all library functions and other library APIs present,
but no standard pragma support).
The macros are defined for now with their TS 18661-1 values. C2X will
give them new values (listed as yyyymmL in the working drafts until
the final standard), at which point there will be the question of what
value to use in stdc-predef.h (where it could depend on
__STDC_VERSION__, but not on feature test macros defined by the user).
My inclination then would be to use the C2X value unconditionally
rather than using an older value to indicate TS support, and only have
any C standard version conditionals for the value when subsequent C
standard versions define further values.
(Note that I'm also inclined, when we implement the C2X change to the
return types of fromfp functions, to make that change unconditional
much like the change made to the types of totalorder functions, with
the old version only supported with compat symbols for already-linked
programs and not as an API for newly built objects. So using the C2X
value would also accurately reflect not supporting the versions of
APIs in the TS where those ended up being incompatible with the first
version actually added to the standard.)
Tested for x86_64.
It turns out the __SSE2_MATH__ conditional in sysdeps/x86/fpu/s_ffma.c
does not cover all cases where the x86 fenv_private.h macros might
manipulate one of the SSE and 387 floating-point state, while the
actual fma implementation uses the other. Specifically, in the 32-bit
case, with a compiler not defaulting to -mfpmath=sse, but testing on a
processor with hardware FMA support, the multiarch fma function
implementations will end up using SSE, while the fenv_private.h macros
will use the 387 state for double. Change the conditional to use the
default macros rather than the optimized ones in all cases except when
the compiler inlines an fma instruction (in which case, since all
those instructions are SSE instructions and -mfpmath=sse must be in
effect for them to be inlined, the optimized macros will only use the
SSE state and it's OK for them to only use the SSE state).
Tested for x86_64 and x86. H.J. reports in
<https://sourceware.org/pipermail/libc-alpha/2021-September/131367.html>
that it fixes the problems he observed.
This drops reliance on _GLOBAL_OFFSET_TABLE_[0] being the link-time
address of _DYNAMIC.
The code sequence length does not change.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
This patch disables A64FX memcpy/memmove BTI instruction insertion
unconditionally such as A64FX memset patch [1] for performance.
[1] commit 07b427296b
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
When testing nptl/tst-pthread-attr-affinity-fail fails with:
error: xsysconf.c:33: sysconf (83): Cannot allocate memory
error: 1 test failures
This happens as xsysconf checks the errno after running sysconf.
Internally the sysconf request for _SC_NPROCESSORS_CONF on linux
allocates memory. But there is a problem, even though malloc succeeds
errno is getting set to ENOMEM.
POSIX allows successful calls to clobber errno. So xsysconf just
checking errno is wrong. Fix xsysconf by only failing if we have an
error result and errno is set.
Avoid defining f64xfmaf128 twice when building s_fmaf128.c.
This can be reproduced on powerpc64le whenever f128 functions do not
have IFUNC enabled, e.g. using "--with-cpu=power8 --disable-multi-arch", or
when using "-with-cpu=power9".
Fixes: b3f27d8150 ("Add narrowing fma functions")
On 32-bit x86 with -mfpmath=sse, and on x86_64 with
--disable-multi-arch, the tests of ffma and its aliases (fma narrowing
from binary64 to binary32) fail. This is probably the issue reported
by H.J. in
<https://sourceware.org/pipermail/libc-alpha/2021-September/131277.html>.
The problem is the use of fenv_private.h macros in the round-to-odd
implementation. Those macros are set up to manipulate only one of the
SSE and 387 floating-point state, whichever is relevant for the type
indicated by the suffix on the macro name. But x86 configurations
sometimes use the ldbl-96 implementation of binary64 fma (that's where
--disable-multi-arch is relevant for x86_64: it causes the ldbl-96
implementation to be used, instead of an IFUNC implementation that
falls back to the dbl-64 version), contrary to the expectations of
those macros for functions operating on double when __SSE2_MATH__ is
defined.
This can be addressed by using the default versions of those macros
(giving x86 its own version of s_ffma.c), as is done for the *f128
macro variants where it depends on the details of how GCC was
configured when building libgcc which floating-point state is affected
by _Float128 arithmetic. The issue only applies when __SSE2_MATH__ is
defined, and doesn't apply when __FP_FAST_FMA is defined (because in
that case, fma will be inlined by the compiler, meaning it's
definitely an SSE operation; for the same reason, this is not an issue
for narrowing sqrt, as hardware sqrt is always inlined in that
implementation for x86), but in other cases it's safest to use the
default versions of the fenv_private.h macros to ensure things work
whichever fma implementation is used.
Tested for x86_64 (with and without --disable-multi-arch) and x86
(with and without -mfpmath=sse).
Instead of checking a pointer argument for NULL, use helper macros
defined differently in the non-positional and positional cases.
This avoids frequent conditional checks and a GCC 12 warning
about comparing pointers against NULL which cannot be NULL.
A lot of the code is unique to the positional and non-positional
code. Also unify the decimal and hexadecimal cases via the new
helper function __printf_fp_spec.
As part of the fix for bug 12889, signals are blocked during
thread exit, so that application code cannot run on the thread that
is about to exit. This would cause problems if the application
expected signals to be delivered after the signal handler revealed
the thread to still exist, despite pthread_kill can no longer be used
to send signals to it. However, glibc internally uses the SIGSETXID
signal in a way that is incompatible with signal blocking, due to the
way the setxid handshake delays thread exit until the setxid operation
has completed. With a blocked SIGSETXID, the handshake can never
complete, causing a deadlock.
As a band-aid, restore the previous handshake protocol by not blocking
SIGSETXID during thread exit.
The new test sysdeps/pthread/tst-pthread-setuid-loop.c is based on
a downstream test by Martin Osvald.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
This patch adds the narrowing fused multiply-add functions from TS
18661-1 / TS 18661-3 / C2X to glibc's libm: ffma, ffmal, dfmal,
f32fmaf64, f32fmaf32x, f32xfmaf64 for all configurations; f32fmaf64x,
f32fmaf128, f64fmaf64x, f64fmaf128, f32xfmaf64x, f32xfmaf128,
f64xfmaf128 for configurations with _Float64x and _Float128;
__f32fmaieee128 and __f64fmaieee128 aliases in the powerpc64le case
(for calls to ffmal and dfmal when long double is IEEE binary128).
Corresponding tgmath.h macro support is also added.
The changes are mostly similar to those for the other narrowing
functions previously added, especially that for sqrt, so the
description of those generally applies to this patch as well. As with
sqrt, I reused the same test inputs in auto-libm-test-in as for
non-narrowing fma rather than adding extra or separate inputs for
narrowing fma. The tests in libm-test-narrow-fma.inc also follow
those for non-narrowing fma.
The non-narrowing fma has a known bug (bug 6801) that it does not set
errno on errors (overflow, underflow, Inf * 0, Inf - Inf). Rather
than fixing this or having narrowing fma check for errors when
non-narrowing does not (complicating the cases when narrowing fma can
otherwise be an alias for a non-narrowing function), this patch does
not attempt to check for errors from narrowing fma and set errno; the
CHECK_NARROW_FMA macro is still present, but as a placeholder that
does nothing, and this missing errno setting is considered to be
covered by the existing bug rather than needing a separate open bug.
missing-errno annotations are duly added to many of the
auto-libm-test-in test inputs for fma.
This completes adding all the new functions from TS 18661-1 to glibc,
so will be followed by corresponding stdc-predef.h changes to define
__STDC_IEC_60559_BFP__ and __STDC_IEC_60559_COMPLEX__, as the support
for TS 18661-1 will be at a similar level to that for C standard
floating-point facilities up to C11 (pragmas not implemented, but
library functions done). (There are still further changes to be done
to implement changes to the types of fromfp functions from N2548.)
Tested as followed: natively with the full glibc testsuite for x86_64
(GCC 11, 7, 6) and x86 (GCC 11); with build-many-glibcs.py with GCC
11, 7 and 6; cross testing of math/ tests for powerpc64le, powerpc32
hard float, mips64 (all three ABIs, both hard and soft float). The
different GCC versions are to cover the different cases in tgmath.h
and tgmath.h tests properly (GCC 6 has _Float* only as typedefs in
glibc headers, GCC 7 has proper _Float* support, GCC 8 adds
__builtin_tgmath).
We can't relocate entries in dynamic section if it is readonly:
1. Add a l_ld_readonly field to struct link_map to indicate if dynamic
section is readonly and set it based on p_flags of PT_DYNAMIC segment.
2. Replace DL_RO_DYN_SECTION with dl_relocate_ld to decide if dynamic
section should be relocated.
3. Remove DL_RO_DYN_TEMP_CNT.
4. Don't use a static dynamic section to make readonly dynamic section
in vDSO writable.
5. Remove the temp argument from elf_get_dynamic_info.
This fixes BZ #28340.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
As described in bug 28358, the round-to-odd computations used in the
libm functions that round their results to a narrower format can yield
spurious underflow exceptions in the following circumstances: the
narrowing only narrows the precision of the type and not the exponent
range (i.e., it's narrowing _Float128 to _Float64x on x86_64, x86 or
ia64), the architecture does after-rounding tininess detection (which
applies to all those architectures), the result is inexact, tiny
before rounding but not tiny after rounding (with the chosen rounding
mode) for _Float64x (which is possible for narrowing mul, div and fma,
not for narrowing add, sub or sqrt), so the underflow exception
resulting from the toward-zero computation in _Float128 is spurious
for _Float64x.
Fixed by making ROUND_TO_ODD call feclearexcept (FE_UNDERFLOW) in the
problem cases (as indicated by an extra argument to the macro); there
is never any need to preserve underflow exceptions from this part of
the computation, because the conversion of the round-to-odd value to
the narrower type will underflow in exactly the cases in which the
function should raise that exception, but it may be more efficient to
avoid the extra manipulation of the floating-point environment when
not needed.
Tested for x86_64 and x86, and with build-many-glibcs.py.
Copy regex-related files back from Gnulib, to fix a problem with
static checking of regex calls noted by Martin Sebor. This merges the
following changes:
* New macro __attribute_nonnull__ in misc/sys/cdefs.h, for use later
when copying other files back from Gnulib.
* Use __GNULIB_CDEFS instead of __GLIBC__ when deciding
whether to include bits/wordsize.h etc.
* Avoid duplicate entries in epsilon closure table.
* New regex.h macro _REGEX_NELTS to let regexec say that its pmatch
arg should contain nmatch elts. Use that for regexec, instead of
__attr_access (which is incorrect).
* New regex.h macro _Attr_access_ which is like __attr_access except
portable to non-glibc platforms.
* Add some DEBUG_ASSERTs to pacify gcc -fanalyzer and to catch
recently-fixed performance bugs if they recur.
* Add Gnulib-specific stuff to port the dynarray- and lock-using parts
of regex code to non-glibc platforms.
* Fix glibc bug 11053.
* Avoid some undefined behavior when popping an empty fail stack.
Recent binutils commit b25f942e18d6ecd7ec3e2d2e9930eb4f996c258a
changes the behavior of `.machine` directives to override, rather
than augment, the base CPU. This can result in _reduced_ functionality
when, for example, compiling for default machine "power8", but explicitly
asking for ".machine power5", which loses Altivec instructions.
In tst-ucontext-ppc64-vscr.c, while the instructions provoking the new
error messages are bracketed by ".machine power5", which is ostensibly
Power ISA 2.03 (POWER5), the POWER5 processor did not support the
VSX subset, so these instructions are not recognized as "power5".
Error: unrecognized opcode: `vspltisb'
Error: unrecognized opcode: `vpkuwus'
Error: unrecognized opcode: `mfvscr'
Error: unrecognized opcode: `stvx'
Manually adding the VSX subset via ".machine altivec" is sufficient.
Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
