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2025-04-25linux/termio: remove <termio.h> and struct termioH. Peter Anvin1-11/+0
The <termio.h> interface is absolutely ancient: it was obsoleted by <termios.h> already in the first version of POSIX (1988) and thus predates the very first version of Linux. Unfortunately, some constant macros are used both by <termio.h> and <termios.h>; particularly problematic is the baud rate constants since the termio interface *requires* that the baud rate is set via an enumeration as part of c_cflag. In preparation of revamping the termios interface to support the arbitrary baud rate capability that the Linux kernel has supported since 2008, remove <termio.h> in the hope that no one still uses this archaic interface. Note that there is no actual code in glibc to support termio: it is purely an unabstracted ioctl() interface. Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com> Reviewed-by: Florian Weimer <fweimer@redhat.com>
2025-04-08stdlib: Implement C2Y uabs, ulabs, ullabs and uimaxabsLenard Mollenkopf4-0/+16
C2Y adds unsigned versions of the abs functions (see C2Y draft N3467 and proposal N3349). Tested for x86_64. Signed-off-by: Lenard Mollenkopf <glibc@lenardmollenkopf.de>
2025-04-02sysdeps: powerpc: restore -mlong-double-128 checkSam James2-0/+117
We mistakenly dropped the check in 27b96e069aad17cefea9437542180bff448ac3a0; there's some other checks which we *can* drop, but let's worry about that later. Fixes the build on ppc64le where GCC is configured with --with-long-double-format=ieee. Reviewed-by: Andreas Schwab <schwab@suse.de>
2025-03-31Raise the minimum GCC version to 12.1 [BZ #32539]H.J. Lu2-117/+0
For all Linux distros with glibc 2.40 which I can find, GCC 14.2 is used to compile glibc 2.40: OS GCC URL AOSC 14.2.0 https://aosc.io/ Arch Linux 14.2.0 https://archlinux.org/ ArchPOWER 14.2.0 https://archlinuxpower.org/ Artix 14.2.0 https://artixlinux.org/ Debian 14.2.0 https://www.debian.org/ Devuan 14.2.0 https://www.devuan.org/ Exherbo 14.2.0 https://www.exherbolinux.org/ Fedora 14.2.1 https://fedoraproject.org/ Gentoo 14.2.1 https://gentoo.org/ Kali Linux 14.2.0 https://www.kali.org/ KaOS 14.2.0 https://kaosx.us/ LiGurOS 14.2.0 https://liguros.gitlab.io/ Mageia 14.2.0 https://www.mageia.org/en/ Manjaro 14.2.0 https://manjaro.org/ NixOS 14.2.0 https://nixos.org/ openmamba 14.2.0 https://openmamba.org/ OpenMandriva 14.2.0 https://openmandriva.org/ openSUSE 14.2.0 https://www.opensuse.org/ Parabola 14.2.0 https://www.parabola.nu/ PLD Linux 14.2.0 https://pld-linux.org/ PureOS 14.2.0 https://pureos.net/ Raspbian 14.2.0 http://raspbian.org/ Slackware 14.2.0 http://www.slackware.com/ Solus 14.2.0 https://getsol.us/ T2 SDE 14.2.0 http://t2sde.org/ Ubuntu 14.2.0 https://www.ubuntu.com/ Wikidata 14.2.0 https://wikidata.org/ Support older versions of GCC to build glibc 2.42: 1. Need to work around bugs in older versions of GCC. 2. Can't use the new features in newer versions of GCC, which may be required for new features, like _Float16 which requires GCC 12.1 or above, in glibc, The main benefit of supporting older versions of GCC is easier backport of bug fixes to the older releases of glibc, which can be mitigated by avoiding incompatible features in newer versions of GCC for critical bug fixes. Require GCC 12.1 or newer to build. Remove GCC version check for PowerPC and s390x. TEST_CC and TEST_CXX can be used to test the glibc build with the older versions of GCC. For glibc developers who are using Linux OSes which don't come with GCC 12.1 or newer, they should build and install GCC 12.1 or newer to work on glibc. This fixes BZ #32539. Signed-off-by: H.J. Lu <hjl.tools@gmail.com> Reviewed-by: Sam James <sam@gentoo.org>
2025-03-27Implement C23 pownJoseph Myers4-0/+27
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the pown functions, which are like pow but with an integer exponent. That exponent has type long long int in C23; it was intmax_t in TS 18661-4, and as with other interfaces changed after their initial appearance in the TS, I don't think we need to support the original version of the interface. The test inputs are based on the subset of test inputs for pow that use integer exponents that fit in long long. As the first such template implementation that saves and restores the rounding mode internally (to avoid possible issues with directed rounding and intermediate overflows or underflows in the wrong rounding mode), support also needed to be added for using SET_RESTORE_ROUND* in such template function implementations. This required math-type-macros-float128.h to include <fenv_private.h>, so it can tell whether SET_RESTORE_ROUNDF128 is defined. In turn, the include order with <fenv_private.h> included before <math_private.h> broke loongarch builds, showing up that sysdeps/loongarch/math_private.h is really a fenv_private.h file (maybe implemented internally before the consistent split of those headers in 2018?) and needed to be renamed to fenv_private.h to avoid errors with duplicate macro definitions if <math_private.h> is included after <fenv_private.h>. The underlying implementation uses __ieee754_pow functions (called more than once in some cases, where the exponent does not fit in the floating type). I expect a custom implementation for a given format, that only handles integer exponents but handles larger exponents directly, could be faster and more accurate in some cases. I encourage searching for worst cases for ulps error for these implementations (necessarily non-exhaustively, given the size of the input space). Tested for x86_64 and x86, and with build-many-glibcs.py.
2025-03-24Add _FORTIFY_SOURCE support for inet_ptonAaron Merey4-0/+4
Add function __inet_pton_chk which calls __chk_fail when the size of argument dst is too small. inet_pton is redirected to __inet_pton_chk or __inet_pton_warn when _FORTIFY_SOURCE is > 0. Also add tests to debug/tst-fortify.c, update the abilist with __inet_pton_chk and mention inet_pton fortification in maint.texi. Co-authored-by: Frédéric Bérat <fberat@redhat.com> Reviewed-by: Florian Weimer <fweimer@redhat.com>
2025-03-21Add _FORTIFY_SOURCE support for inet_ntopFrédéric Bérat4-0/+4
- Create the __inet_ntop_chk routine that verifies that the builtin size of the destination buffer is at least as big as the size given by the user. - Redirect calls from inet_ntop to __inet_ntop_chk or __inet_ntop_warn - Update the abilist for this new routine - Update the manual to mention the new fortification Reviewed-by: Florian Weimer <fweimer@redhat.com>
2025-03-14Implement C23 powrJoseph Myers4-0/+27
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the powr functions, which are like pow, but with simpler handling of special cases (based on exp(y*log(x)), so negative x and 0^0 are domain errors, powers of -0 are always +0 or +Inf never -0 or -Inf, and 1^+-Inf and Inf^0 are also domain errors, while NaN^0 and 1^NaN are NaN). The test inputs are taken from those for pow, with appropriate adjustments (including removing all tests that would be domain errors from those in auto-libm-test-in and adding some more such tests in libm-test-powr.inc). The underlying implementation uses __ieee754_pow functions after dealing with all special cases that need to be handled differently. It might be a little faster (avoiding a wrapper and redundant checks for special cases) to have an underlying implementation built separately for both pow and powr with compile-time conditionals for special-case handling, but I expect the benefit of that would be limited given that both functions will end up needing to use the same logic for computing pow outside of special cases. My understanding is that powr(negative, qNaN) should raise "invalid": that the rule on "invalid" for an argument outside the domain of the function takes precedence over a quiet NaN argument producing a quiet NaN result with no exceptions raised (for rootn it's explicit that the 0th root of qNaN raises "invalid"). I've raised this on the WG14 reflector to confirm the intent. Tested for x86_64 and x86, and with build-many-glibcs.py.
2025-03-12Update syscall lists for Linux 6.13Joseph Myers2-0/+8
Linux 6.13 adds four new syscalls. Update syscall-names.list and regenerate the arch-syscall.h headers with build-many-glibcs.py update-syscalls. Tested with build-many-glibcs.py.
2025-03-12Linux: Add the pthread_gettid_np function (bug 27880)Florian Weimer4-0/+4
Current Bionic has this function, with enhanced error checking (the undefined case terminates the process). Reviewed-by: Joseph Myers <josmyers@redhat.com>
2025-03-07Implement C23 rsqrtJoseph Myers4-0/+27
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the rsqrt functions (1/sqrt(x)). The test inputs are taken from those for sqrt. Tested for x86_64 and x86, and with build-many-glibcs.py.
2025-03-05Remove dl-procinfo.hAdhemerval Zanella1-1/+0
powerpc was the only architecture with arch-specific hooks for LD_SHOW_AUXV, and with the information moved to ld diagnostics there is no need to keep the _dl_procinfo hook. Checked with a build for all affected ABIs. Reviewed-by: Peter Bergner <bergner@linux.ibm.com>
2025-03-05powerpc: Remove unused dl-procinfo.hAdhemerval Zanella2-0/+2
The _dl_string_platform is moved to hwcapinfo.h, since it is only used by hwcapinfo.c and test-get_hwcap internal test. Checked on powerpc64le-linux-gnu. Reviewed-by: Peter Bergner <bergner@linux.ibm.com>
2025-03-05powerpc: Move AT_HWCAP descriptions to ld diagnosticsAdhemerval Zanella5-118/+179
The ld.so diagnostics already prints AT_HWCAP values, but only in hexadecimal. To avoid duplicating the strings, consolidate the hwcap_names from cpu-features.h on a new file, dl-hwcap-info.h (and it also improves the hwcap string description with more values). For future AT_HWCAP3/AT_HWCAP4 extensions, it is just a matter to add them on dl-hwcap-info.c so both ld diagnostics and tunable filtering will parse the new values. Checked on powerpc64le-linux-gnu. Reviewed-by: Peter Bergner <bergner@linux.ibm.com>
2025-01-01Update copyright dates with scripts/update-copyrightsPaul Eggert97-97/+97
2024-12-12Implement C23 atan2piJoseph Myers4-0/+27
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the atan2pi functions (atan2(y,x)/pi). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-12-11Implement C23 atanpiJoseph Myers4-0/+27
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the atanpi functions (atan(x)/pi). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-12-10Implement C23 asinpiJoseph Myers4-0/+27
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the asinpi functions (asin(x)/pi). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-12-09Implement C23 acospiJoseph Myers4-0/+27
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the acospi functions (acos(x)/pi). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-12-09powerpc64le: ROP changes for the *context and setjmp functionsSachin Monga4-12/+54
Add ROP protection for the getcontext, setcontext, makecontext, swapcontext and __sigsetjmp_symbol functions. Reviewed-by: Peter Bergner <bergner@linux.ibm.com>
2024-12-05Implement C23 tanpiJoseph Myers4-0/+27
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the tanpi functions (tan(pi*x)). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-12-04Implement C23 sinpiJoseph Myers4-0/+27
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the sinpi functions (sin(pi*x)). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-12-04Implement C23 cospiJoseph Myers4-0/+27
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the cospi functions (cos(pi*x)). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-11-19powerpc: Improve the inline asm for syscall wrappersPeter Bergner1-20/+22
Update the inline asm syscall wrappers to match the newer register constraint usage in INTERNAL_VSYSCALL_CALL_TYPE. Use the faster mfocrf instruction when available, rather than the slower mfcr microcoded instruction.
2024-11-12linux: Add support for getrandom vDSOAdhemerval Zanella1-0/+1
Linux 6.11 has getrandom() in vDSO. It operates on a thread-local opaque state allocated with mmap using flags specified by the vDSO. Multiple states are allocated at once, as many as fit into a page, and these are held in an array of available states to be doled out to each thread upon first use, and recycled when a thread terminates. As these states run low, more are allocated. To make this procedure async-signal-safe, a simple guard is used in the LSB of the opaque state address, falling back to the syscall if there's reentrancy contention. Also, _Fork() is handled by blocking signals on opaque state allocation (so _Fork() always sees a consistent state even if it interrupts a getrandom() call) and by iterating over the thread stack cache on reclaim_stack. Each opaque state will be in the free states list (grnd_alloc.states) or allocated to a running thread. The cancellation is handled by always using GRND_NONBLOCK flags while calling the vDSO, and falling back to the cancellable syscall if the kernel returns EAGAIN (would block). Since getrandom is not defined by POSIX and cancellation is supported as an extension, the cancellation is handled as 'may occur' instead of 'shall occur' [1], meaning that if vDSO does not block (the expected behavior) getrandom will not act as a cancellation entrypoint. It avoids a pthread_testcancel call on the fast path (different than 'shall occur' functions, like sem_wait()). It is currently enabled for x86_64, which is available in Linux 6.11, and aarch64, powerpc32, powerpc64, loongarch64, and s390x, which are available in Linux 6.12. Link: https://pubs.opengroup.org/onlinepubs/9799919799/nframe.html [1] Co-developed-by: Jason A. Donenfeld <Jason@zx2c4.com> Tested-by: Jason A. Donenfeld <Jason@zx2c4.com> # x86_64 Tested-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> # x86_64, aarch64 Tested-by: Xi Ruoyao <xry111@xry111.site> # x86_64, aarch64, loongarch64 Tested-by: Stefan Liebler <stli@linux.ibm.com> # s390x
2024-10-30powerpc64: Obviate the need for ROP protection in clone/clone3Sachin Monga2-21/+21
Save lr in a non-volatile register before scv in clone/clone3. For clone, the non-volatile register was unused and already saved/restored. Remove the dead code from clone. Signed-off-by: Sachin Monga <smonga@linux.ibm.com> Reviewed-by: Peter Bergner <bergner@linux.ibm.com>
2024-09-24misc: Enable internal use of memory protection keysFlorian Weimer2-2/+6
This adds the necessary hidden prototypes.
2024-09-11Linux: Add the sched_setattr and sched_getattr functionsFlorian Weimer4-0/+8
And struct sched_attr. In sysdeps/unix/sysv/linux/bits/sched.h, the hack that defines sched_param around the inclusion of <linux/sched/types.h> is quite ugly, but the definition of struct sched_param has already been dropped by the kernel, so there is nothing else we can do and maintain compatibility of <sched.h> with a wide range of kernel header versions. (An alternative would involve introducing a separate header for this functionality, but this seems unnecessary.) The existing sched_* functions that change scheduler parameters are already incompatible with PTHREAD_PRIO_PROTECT mutexes, so there is no harm in adding more functionality in this area. The documentation mostly defers to the Linux manual pages. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2024-08-23nptl: Fix Race conditions in pthread cancellation [BZ#12683]Adhemerval Zanella2-0/+151
The current racy approach is to enable asynchronous cancellation before making the syscall and restore the previous cancellation type once the syscall returns, and check if cancellation has happen during the cancellation entrypoint. As described in BZ#12683, this approach shows 2 problems: 1. Cancellation can act after the syscall has returned from the kernel, but before userspace saves the return value. It might result in a resource leak if the syscall allocated a resource or a side effect (partial read/write), and there is no way to program handle it with cancellation handlers. 2. If a signal is handled while the thread is blocked at a cancellable syscall, the entire signal handler runs with asynchronous cancellation enabled. This can lead to issues if the signal handler call functions which are async-signal-safe but not async-cancel-safe. For the cancellation to work correctly, there are 5 points at which the cancellation signal could arrive: [ ... )[ ... )[ syscall ]( ... 1 2 3 4 5 1. Before initial testcancel, e.g. [*... testcancel) 2. Between testcancel and syscall start, e.g. [testcancel...syscall start) 3. While syscall is blocked and no side effects have yet taken place, e.g. [ syscall ] 4. Same as 3 but with side-effects having occurred (e.g. a partial read or write). 5. After syscall end e.g. (syscall end...*] And libc wants to act on cancellation in cases 1, 2, and 3 but not in cases 4 or 5. For the 4 and 5 cases, the cancellation will eventually happen in the next cancellable entrypoint without any further external event. The proposed solution for each case is: 1. Do a conditional branch based on whether the thread has received a cancellation request; 2. It can be caught by the signal handler determining that the saved program counter (from the ucontext_t) is in some address range beginning just before the "testcancel" and ending with the syscall instruction. 3. SIGCANCEL can be caught by the signal handler and determine that the saved program counter (from the ucontext_t) is in the address range beginning just before "testcancel" and ending with the first uninterruptable (via a signal) syscall instruction that enters the kernel. 4. In this case, except for certain syscalls that ALWAYS fail with EINTR even for non-interrupting signals, the kernel will reset the program counter to point at the syscall instruction during signal handling, so that the syscall is restarted when the signal handler returns. So, from the signal handler's standpoint, this looks the same as case 2, and thus it's taken care of. 5. For syscalls with side-effects, the kernel cannot restart the syscall; when it's interrupted by a signal, the kernel must cause the syscall to return with whatever partial result is obtained (e.g. partial read or write). 6. The saved program counter points just after the syscall instruction, so the signal handler won't act on cancellation. This is similar to 4. since the program counter is past the syscall instruction. So The proposed fixes are: 1. Remove the enable_asynccancel/disable_asynccancel function usage in cancellable syscall definition and instead make them call a common symbol that will check if cancellation is enabled (__syscall_cancel at nptl/cancellation.c), call the arch-specific cancellable entry-point (__syscall_cancel_arch), and cancel the thread when required. 2. Provide an arch-specific generic system call wrapper function that contains global markers. These markers will be used in SIGCANCEL signal handler to check if the interruption has been called in a valid syscall and if the syscalls has side-effects. A reference implementation sysdeps/unix/sysv/linux/syscall_cancel.c is provided. However, the markers may not be set on correct expected places depending on how INTERNAL_SYSCALL_NCS is implemented by the architecture. It is expected that all architectures add an arch-specific implementation. 3. Rewrite SIGCANCEL asynchronous handler to check for both canceling type and if current IP from signal handler falls between the global markers and act accordingly. 4. Adjust libc code to replace LIBC_CANCEL_ASYNC/LIBC_CANCEL_RESET to use the appropriate cancelable syscalls. 5. Adjust 'lowlevellock-futex.h' arch-specific implementations to provide cancelable futex calls. Some architectures require specific support on syscall handling: * On i386 the syscall cancel bridge needs to use the old int80 instruction because the optimized vDSO symbol the resulting PC value for an interrupted syscall points to an address outside the expected markers in __syscall_cancel_arch. It has been discussed in LKML [1] on how kernel could help userland to accomplish it, but afaik discussion has stalled. Also, sysenter should not be used directly by libc since its calling convention is set by the kernel depending of the underlying x86 chip (check kernel commit 30bfa7b3488bfb1bb75c9f50a5fcac1832970c60). * mips o32 is the only kABI that requires 7 argument syscall, and to avoid add a requirement on all architectures to support it, mips support is added with extra internal defines. Checked on aarch64-linux-gnu, arm-linux-gnueabihf, powerpc-linux-gnu, powerpc64-linux-gnu, powerpc64le-linux-gnu, i686-linux-gnu, and x86_64-linux-gnu. [1] https://lkml.org/lkml/2016/3/8/1105 Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2024-07-30Update syscall lists for Linux 6.10Adhemerval Zanella2-0/+2
Linux 6.10 changes for syscall are: * mseal for all architectures. * map_shadow_stack for x32. * Replace sync_file_range with sync_file_range2 for csky (which fixes a broken sync_file_range usage). Update syscall-names.list and regenerate the arch-syscall.h headers with build-many-glibcs.py update-syscalls. Tested with build-many-glibcs.py. Reviewed-by: Florian Weimer <fweimer@redhat.com>
2024-06-17Convert to autoconf 2.72 (vanilla release, no distribution patches)Andreas K. Hüttel2-85/+87
As discussed at the patch review meeting Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org> Reviewed-by: Simon Chopin <simon.chopin@canonical.com>
2024-06-17Implement C23 exp2m1, exp10m1Joseph Myers4-0/+54
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the exp2m1 and exp10m1 functions (exp2(x)-1 and exp10(x)-1, like expm1). As with other such functions, these use type-generic templates that could be replaced with faster and more accurate type-specific implementations in future. Test inputs are copied from those for expm1, plus some additions close to the overflow threshold (copied from exp2 and exp10) and also some near the underflow threshold. exp2m1 has the unusual property of having an input (M_MAX_EXP) where whether the function overflows (under IEEE semantics) depends on the rounding mode. Although these could reasonably be XFAILed in the testsuite (as we do in some cases for arguments very close to a function's overflow threshold when an error of a few ulps in the implementation can result in the implementation not agreeing with an ideal one on whether overflow takes place - the testsuite isn't smart enough to handle this automatically), since these functions aren't required to be correctly rounding, I made the implementation check for and handle this case specially. The Makefile ordering expected by lint-makefiles for the new functions is a bit peculiar, but I implemented it in this patch so that the test passes; I don't know why log2 also needed moving in one Makefile variable setting when it didn't in my previous patches, but the failure showed a different place was expected for that function as well. The powerpc64le IFUNC setup seems not to be as self-contained as one might hope; it shouldn't be necessary to add IFUNCs for new functions such as these simply to get them building, but without setting up IFUNCs for the new functions, there were undefined references to __GI___expm1f128 (that IFUNC machinery results in no such function being defined, but doesn't stop include/math.h from doing the redirection resulting in the exp2m1f128 and exp10m1f128 implementations expecting to call it). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-06-17Implement C23 log10p1Joseph Myers4-0/+27
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the log10p1 functions (log10(1+x): like log1p, but for base-10 logarithms). This is directly analogous to the log2p1 implementation (except that whereas log2p1 has a smaller underflow range than log1p, log10p1 has a larger underflow range). The test inputs are copied from those for log1p and log2p1, plus a few more inputs in that wider underflow range. Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-06-17Implement C23 logp1Joseph Myers4-0/+27
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the logp1 functions (aliases for log1p functions - the name is intended to be more consistent with the new log2p1 and log10p1, where clearly it would have been very confusing to name those functions log21p and log101p). As aliases rather than new functions, the content of this patch is somewhat different from those actually adding new functions. Tests are shared with log1p, so this patch *does* mechanically update all affected libm-test-ulps files to expect the same errors for both functions. The vector versions of log1p on aarch64 and x86_64 are *not* updated to have logp1 aliases (and thus there are no corresponding header, tests, abilist or ulps changes for vector functions either). It would be reasonable for such vector aliases and corresponding changes to other files to be made separately. For now, the log1p tests instead avoid testing logp1 in the vector case (a Makefile change is needed to avoid problems with grep, used in generating the .c files for vector function tests, matching more than one ALL_RM_TEST line in a file testing multiple functions with the same inputs, when it assumes that the .inc file only has a single such line). Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-05-21Remove the clone3 symbol from libc.a [BZ #31770]H.J. Lu1-1/+0
clone3 isn't exported from glibc and is hidden in libc.so. Fix BZ #31770 by removing clone3 alias. Signed-off-by: H.J. Lu <hjl.tools@gmail.com> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
2024-05-20Implement C23 log2p1Joseph Myers4-0/+27
C23 adds various <math.h> function families originally defined in TS 18661-4. Add the log2p1 functions (log2(1+x): like log1p, but for base-2 logarithms). This illustrates the intended structure of implementations of all these function families: define them initially with a type-generic template implementation. If someone wishes to add type-specific implementations, it is likely such implementations can be both faster and more accurate than the type-generic one and can then override it for types for which they are implemented (adding benchmarks would be desirable in such cases to demonstrate that a new implementation is indeed faster). The test inputs are copied from those for log1p. Note that these changes make gen-auto-libm-tests depend on MPFR 4.2 (or later). The bulk of the changes are fairly generic for any such new function. (sysdeps/powerpc/nofpu/Makefile only needs changing for those type-generic templates that use fabs.) Tested for x86_64 and x86, and with build-many-glibcs.py.
2024-04-19