Clang issues a warning for double alias redirection, indicating that thei
original symbol is used even if a weak definition attempts to override it.
For instance, in the construction:
int __internal_impl (...) {}
weak_alias (__internal_impl, external_impl);
#if SOMETHING
weak_alias (external_impl, another_external_impl)
#endif
Clang warns that another_external_impl always resolves to __internal_impl,
even if external_impl is a weak reference. Using the internal symbol for
both aliases resolves this warning.
This issue also occurs with certain libc_hidden_def usage:
int __internal_impl (...) {}
weak_alias (__internal_impl, __internal_alias)
libc_hidden_weak (__internal_alias)
In this case, using a strong_alias is sufficient to avoid the warning
(since the alias is internal, there is no need to use a weak alias).
However, for the constructions like:
int __internal_impl (...) {}
weak_alias (__internal_impl, __internal_alias)
libc_hidden_def (__internal_alias)
weak_alias (__internal_impl, external_alias)
libc_hidden_def (external_alias)
Clang warns that the internal external_alias will always resolve to
__GI___internal_impl, even if a weak definition of __GI_internal_impl is
overridden. For this case, a new macro named static_weak_alias is used
to create a strong alias for SHARED, or a weak_alias otherwise.
With these changes, there is no need to check and enable the
-Wno-ignored-attributes suppression when using clang.
Checked with a build on affected ABIs, and a full check on aarch64,
armhf, i686, and x86_64.
Reviewed-by: Sam James <sam@gentoo.org>
Since the variadic prctl function takes at most 5 integer arguments which
are passed in the same integer registers on x32 as the function with 5
integer arguments, we can use assembly for prctl. Since upper 32-bits in
the last 4 arguments of pcrtl must be cleared to match the x32 prctl
syscall interface where the last 4 arguments are unsigned 64 bit longs,
implement prctl in assembly to clear upper 32-bits in the last 4 arguments
and add a test to verify it.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Commit 33eff78c8b caused issues in nbdkit
which had code similar to this to get the last line of the file:
while (getline (&line, &len, fp) != -1)
;
/* Process LINE. */
After that commit, line[0] would be equal to '\0' instead of containing
the last line of the file like before that commit. A recent POSIX issue
clarified that the behavior before and after that commit are allowed,
since the contents of LINE are unspecified after -1 is returned
[1]. However, some programs rely on the previous behavior.
This patch null terminates the buffer upon getdelim/getline's initial
allocation. This is compatible with previous glibc versions, while also
protecting the caller from reading uninitialized memory if the file is
empty, as long as getline/getdelim does the initial allocation.
[1] https://www.austingroupbugs.net/bug_view_page.php?bug_id=1953
Suggested-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Vector variants of the new C23 rsqrt routines for both AdvSIMD and
SVE, as well as in both single and double precision.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Add benchtests for double precision vector rsqrt routine. They are
identical to those found in log2.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Add benchtests for vector single precision rsqrtf. They are
identical to those found in log2f.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The __builtin_fmod{f} and __builtin_remainder{f} were added on gcc 13,
and the minimum supported gcc is 12. This patch adds a configure test
to check whether the compiler enables inlining for fmod/remainder, and
uses inline assembly if not.
Checked on i686-linux-gnu wih gcc-12.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Report assertion failure if the alignment of external pthread structs is
lower than the internal version. This triggers on type mismatches like
in BZ #33632.
Reviewed-by: Yury Khrustalev <yury.khrustalev@arm.com>
Optimise AdvSIMD atanhf by vectorising the special case.
There are asymptotes at x = -1 and x = 1. So return inf for these.
Values for which |x| > 1, return NaN.
R.Throughput difference on V2 with GCC@15:
58-60% improvement in special cases.
No regression in fast pass.
Optimise AdvSIMD asinhf by vectorising the special case.
For values greater than 0x1p64, scale the input down first.
This is because the output will overflow with inputs greater than
or equal to this value as there is a squaring operation in the
algorithm.
To scale, do:
2asinh(sqrt[(x-1)/2])
Because:
2asinh(x) = +-acosh(2x^2 + 1)
Apply opposite operations in opposite order for x, and you get:
asinh(x) = 2acosh(sqrt[(x-1)/2]).
Found that using asinh instead of acosh also very closely
approximates asinh(x) for a high input x.
R.Throughput difference on V2 with GCC@15:
25-58% improvement in special cases.
4% regression in fast pass.
Optimise AdvSIMD acoshf by vectorising the special case.
For values greater than 0x1p64, scale the input down first.
This is because the output will overflow with inputs greater than
or equal to this value as there is a squaring operation in the
algorithm.
To scale, do:
2acosh(sqrt[(x+1)/2])
Because:
acosh(x) = 1/2acosh(2x^2 - 1) for x>=1.
Apply opposite operations in opposite order for x, and you get:
acosh(x) = 2acosh(sqrt[(x+1)/2]).
R.Throughput difference on V2 with GCC@15:
30-49% improvement in special cases.
2% regression in fast pass.
Check that the new tunable changes behaviour correctly:
* When BTI is enforced, any unmarked binary that is loaded
results in an error: either an abort or dlopen error when
this binary is loaded via dlopen.
* When BTI is not enforced, it is OK to load an unmarked
binary.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Add glibc.cpu.aarch64_bti tunable with 2 values:
- permissive (default)
- enforced
and use this tunable to enforce BTI marking on dependencies
when the enforced option is selected.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Tested-by: Jeremy Linton <jeremy.linton@arm.com>
We add configure checks for 3 things:
- Compiler (both CC and TEST_CC) supports -mbranch-protection=bti.
- Linker supports -z force-bti.
- The toolchain supplies object files and target libraries with
the BTI marking.
All three must be true in order for the tests to be valid, so
we check all flags and set the makefile variable accordingly.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Optimise AdvSIMD log10 by vectorising the special case.
For subnormal input values, use the same scaling technique as
described in the single precision equivalent.
Then check for inf, nan and x<=0.
Optimise AdvSIMD log2 by vectorising the special case.
For subnormal input values, use the same scaling technique as
described in the single precision equivalent.
Then check for inf, nan and x<=0.
Optimise AdvSIMD log by vectorising the special case.
For subnormal input values, use the same scaling technique as
described in the single precision equivalent.
Then check for inf, nan and x<=0.
Optimise AdvSIMD log10f by vectorising the special case.
Use scaling technique on subnormal values, then check for inf and
nan values.
The scaling technique will sqrt the input then multiply the output
by 2 because:
log(sqrt(x)) = 1/2(log(x)), so log(x) = 2log(sqrt(x))
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Optimise AdvSIMD log2f by vectorising the special case.
Use scaling technique on subnormal values, then check for inf and
nan values.
The scaling technique used will sqrt the input then multiply the
output by 2 because:
log(sqrt(x)) = 1/2 log(x), so log(x) = 2log(sqrt(x))
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Optimise AdvSIMD logf by vectorising the special case.
Use scaling technique on subnormal values, then check for inf and
nan values.
The scaling technique used will sqrt the input then multiply the
output by 2 because:
log(sqrt(x)) = 1/2 log(x), so log(x) = 2log(sqrt(x))
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Optimise AdvSIMD log1pf by vectorising the special case and by
reducing the range of values passed to the special case.
Previously, high values such as 0x1.1p127 where treated as special
cases, but now the special cases are for when the input is:
Less than or equal to -1
+/- INFINITY
+/- NaN
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
commit 8cd6efca5b
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Thu Nov 20 15:30:06 2025 -0300
Add add_ssaaaa and sub_ssaaaa to gmp-arch.h
checks __WORDSIZE == 32 to decide if int128 should be used, which breaks
x32 which has int128 and __WORDSIZE == 32. Check BITS_PER_MP_LIMB == 32,
instead of __WORDSIZE == 32. This fixes BZ #33677.
Tested on x32, x86-64 and i686.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The TIME_MONOTONIC maps to POSIX's CLOCK_MONOTONIC, TIME_ACTIVE to
CLOCK_PROCESS_CPUTIME_ID, and TIME_THREAD_ACTIVE to
CLOCK_THREAD_CPUTIME_ID.
No Linux specific timer are added as extension.
Co-authored-by: Yonggang Luo <luoyonggang@gmail.com>
Reviewed-by: Paul Eggert <eggert@cs.ucla.edu>
commit 7fec8a5de6
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Thu Nov 13 14:26:08 2025 -0300
Revert __HAVE_64B_ATOMICS configure check
uses 64-bit atomic operations on sem_t if 64-bit atomics are supported.
But sem_t may be aligned to 32-bit on 32-bit architectures.
1. Add a macro, SEM_T_ALIGN, for sem_t alignment.
2. Add a macro, HAVE_UNALIGNED_64B_ATOMICS. Define it if unaligned 64-bit
atomic operations are supported.
3. Add a macro, USE_64B_ATOMICS_ON_SEM_T. Define to 1 if 64-bit atomic
operations are supported and SEM_T_ALIGN is at least 8-byte aligned or
HAVE_UNALIGNED_64B_ATOMICS is defined.
4. Assert that size and alignment of sem_t are not lower than those of
the internal struct new_sem.
5. Check USE_64B_ATOMICS_ON_SEM_T, instead of USE_64B_ATOMICS, when using
64-bit atomic operations on sem_t.
This fixes BZ #33632.
Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Use environment variables to provide mirror URLs to checkout
sources from Git. Each component has a corresponding env var
that will be used if it's present: <component>_GIT_MIRROR.
Note that '<component>' should be upper case, e.g. GLIBC.
Co-authored-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Allow to use custom mirror URLs to download tarballs from a mirror
of ftp.gnu.org using the FTP_GNU_ORG_MIRROR env variable (default
value is 'https://ftp.gnu.org').
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Test wrapper script was used twice: once to run the test
command and second time within the text command which
seems unnecessary and results in false errors when running
this test.
Fixes 332f8e62af
Reviewed-by: Frédéric Bérat <fberat@redhat.com>
The allocation_index was being incremented before checking if mmap()
succeeds. If mmap() fails, allocation_index would still be incremented,
creating a gap in the allocations tracking array and making
allocation_index inconsistent with the actual number of successful
allocations.
This fix moves the allocation_index increment to after the mmap()
success check, ensuring it only increments when an allocation actually
succeeds. This maintains proper tracking for leak detection and
prevents gaps in the allocations array.
Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
The expression inptr + 1 can technically be invalid: if inptr == inend,
inptr may point one element past the end of an array.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
C23 defines library macros __STDC_VERSION_<header>_H__ to indicate
that a header has support for new / changed features from C23. Now
that all the required library features are implemented in glibc,
define these macros. I'm not sure this is sufficiently much of a
user-visible feature to be worth a mention in NEWS.
Tested for x86_64.
There are various optional C23 features we don't yet have, of which I
might look at the Annex H ones (floating-point encoding conversion
functions and _Float16 functions) next.
* Optional time bases TIME_MONOTONIC, TIME_ACTIVE, TIME_THREAD_ACTIVE.
See
<https://sourceware.org/pipermail/libc-alpha/2023-June/149264.html>
- we need to review / update that patch. (I think patch 2/2,
inventing new names for all the nonstandard CLOCK_* supported by the
Linux kernel, is rather more dubious.)
* Updating conform/ tests for C23.
* Defining the rounding mode macro FE_TONEARESTFROMZERO for RISC-V (as
far as I know, the only architecture supported by glibc that has
hardware support for this rounding mode for binary floating point)
and supporting it throughout glibc and its tests (especially the
string/numeric conversions in both directions that explicitly handle
each possible rounding mode, and various tests that do likewise).
* Annex H floating-point encoding conversion functions. (It's not
entirely clear which are optional even given support for Annex H;
there's some wording applied inconsistently about only being
required when non-arithmetic interchange formats are supported; see
the comments I raised on the WG14 reflector on 23 Oct 2025.)
* _Float16 functions (and other header and testcase support for this
type).
* Decimal floating-point support.
* Fully supporting __int128 and unsigned __int128 as integer types
wider than intmax_t, as permitted by C23. Would need doing in
coordination with GCC, see GCC bug 113887 for more discussion of
what's involved.
The current implementation relies on setting the rounding mode for
different calculations (FE_TOWARDZERO) to obtain correctly rounded
results. For most CPUs, this adds significant performance overhead
because it requires executing a typically slow instruction (to
get/set the floating-point status), necessitates flushing the
pipeline, and breaks some compiler assumptions/optimizations.
The original implementation adds tests to handle underflow in corner
cases, whereas this implementation uses a different strategy that
checks both the mantissa and the result to determine whether the
result is not subject to double rounding.
I tested this implementation on various targets (x86_64, i686, arm,
aarch64, powerpc), including some by manually disabling the compiler
instructions.
Performance-wise, it shows large improvements:
reciprocal-throughput master patched improvement
x86_64 [1] 58.09 7.96 7.33x
i686 [1] 279.41 16.97 16.46x
aarch64 [2] 26.09 4.10 6.35x
armhf [2] 30.25 4.20 7.18x
powerpc [3] 9.46 1.46 6.45x
latency master patched improvement
x86_64 64.50 14.25 4.53x
i686 304.39 61.04 4.99x
aarch64 27.71 5.74 4.82x
armhf 33.46 7.34 4.55x
powerpc 10.96 2.65 4.13x
Checked on x86_64-linux-gnu and i686-linux-gnu with —disable-multi-arch,
and on arm-linux-gnueabihf.
[1] gcc 15.2.1, Zen3
[2] gcc 15.2.1, Neoverse N1
[3] gcc 15.2.1, POWER10
Signed-off-by: Szabolcs Nagy <nsz@gcc.gnu.org>
Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Co-authored-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
We only need to enable GCS tests on AArch64 targets, however previously
the configure checks for GCS support in compiler and linker were added
for all targets which was not efficient.
To enable tests for GCS we need 4 things to be true:
- Compiler supports GCS branch protection.
- Test compiler supports GCS branch protection.
- Linker supports GCS marking of binaries.
- The CRT objects provided by the toolchain have GCS marking.
To check for the latter, we add new macro to aclocal.m4 that allows to
grep output from readelf.
We check all four and then put the result in one make variable to
simplify checks in makefiles.
Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
The current implementation relies on setting the rounding mode for
different calculations (first to FE_TONEAREST and then to FE_TOWARDZERO)
to obtain correctly rounded results. For most CPUs, this adds a significant
performance overhead since it requires executing a typically slow
instruction (to get/set the floating-point status), it necessitates
flushing the pipeline, and breaks some compiler assumptions/optimizations.
This patch introduces a new implementation originally written by Szabolcs
for musl, which utilizes mostly integer arithmetic. Floating-point
arithmetic is used to raise the expected exceptions, without the need for
fenv.h operations.
I added some changes compared to the original code:
* Fixed some signaling NaN issues when the 3-argument is NaN.
* Use math_uint128.h for the 64-bit multiplication operation. It allows
the compiler to use 128-bit types where available, which enables some
optimizations on certain targets (for instance, MIPS64).
* Fixed an arm32 issue where the libgcc routine might not respect the
rounding mode [1]. This can also be used on other targets to optimize
the conversion from int64_t to double.
* Use -fexcess-precision=standard on i686.
I tested this implementation on various targets (x86_64, i686, arm, aarch64,
powerpc), including some by manually disabling the compiler instructions.
Performance-wise, it shows large improvements:
reciprocal-throughput master patched improvement
x86_64 [2] 289.4640 22.4396 12.90x
i686 [2] 636.8660 169.3640 3.76x
aarch64 [3] 46.0020 11.3281 4.06x
armhf [3] 63.989 26.5056 2.41x
powerpc [4] 23.9332 6.40205 3.74x
latency master patched improvement
x86_64 293.7360 38.1478 7.70x
i686 658.4160 187.9940 3.50x
aarch64 44.5166 14.7157 3.03x
armhf 63.7678 28.4116 2.24x
power10 23.8561 11.4250 2.09x
Checked on x86_64-linux-gnu and i686-linux-gnu with —disable-multi-arch,
and on arm-linux-gnueabihf.
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91970
[2] gcc 15.2.1, Zen3
[3] gcc 15.2.1, Neoverse N1
[4] gcc 15.2.1, POWER10
Signed-off-by: Szabolcs Nagy <nsz@gcc.gnu.org>
Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
To enable “longlong.h” removal, the umul_ppmm is moved to a gmp-arch.h.
The generic implementation now uses a static inline, which provides
better type checking than the GNU extension to cast the asm constraint
(and it works better with clang).
Most of the architecture uses the generic implementation, which is
expanded from a macro, except for alpha, arm, hppa, x86, m68k, mips,
powerpc, and sparc. The 32 bit architectures the compiler generates
good enough code using uint64_t types, where for 64 bit architecture
the patch leverages the math_u128.h definitions that uses 128-bit
integers when available (all 64 bit architectures on gcc 15).
Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
To enable “longlong.h” removal, add_ssaaaa and sub_ssaaaa are moved to
gmp-arch.h. The generic implementation now uses a static inline. This
provides better type checking than the GNU extension, which casts the
asm constraint; and it also works better with clang.
Most architectures use the generic implementation, with except of
arc, arm, hppa, x86, m68k, powerpc, and sparc. The 32 bit architectures
the compiler generates good enough code using uint64_t types, where
for 64 bit architecture the patch leverages the math_u128.h definitions
that uses 128-bit integers when available (all 64 bit architectures
on gcc 15).
The strongly typed implementation required some changes. I adjusted
_FP_W_TYPE, _FP_WS_TYPE, and _FP_I_TYPE to use the same type as
mp_limb_t on aarch64, powerpc64le, x86_64, and riscv64. This basically
means using “long” instead of “long long.”
Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
To enable “longlong.h” removal, the udiv_qrnnd is moved to a gmp-arch.h
file. It allows each architecture to implement its own arch-specific
optimizations. The generic implementation now uses a static inline,
which provides better type checking than the GNU extension to cast the
asm constraint (and it works better with clang).
Most of the architecture uses the generic implementation, which is
expanded from a macro, except for alpha, x86, m68k, sh, and sparc.
I kept that alpha, which uses out-of-the-line implementations and x86,
where there is no easy way to use the div{q} instruction from C code.
For the rest, the compiler generates good enough code.
The hppa also provides arch-specific implementations, but they are not
routed in “longlong.h” and thus never used.
Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Single-threaded malloc tests exercise only the SINGLE_THREAD_P paths in
the malloc implementation. This commit runs variants of these tests in
a multi-threaded environment in order to exercise the alternate code
paths in the same test scenarios, thus potentially improving coverage.
$(test)-threaded-main and $(test)-threaded-worker variants are
introduced for most single-threaded malloc tests (with a small number of
exceptions). The -main variants run the base test in a main thread
while the test environment has an alternate thread running, whereas the
-worker variants run the test in an alternate thread while the main
thread waits on it.
The tests themselves are unmodified, and the change is accomplished by
using -DTEST_IN_THREAD at compile time, which instructs support/
infrastructure to run the test while an alternate thread waits on it.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Adhemerval Zanella
Florian Weimer
H.J. Lu
Collin Funk
James Chesterman
Wilco Dijkstra
Yury Khrustalev
Joseph Myers
Kacper Piwiński
Osama Abdelkader
Arjun Shankar