mirror of git://sourceware.org/git/glibc.git
8a78f833d6
<tgmath.h> implements semantics for integer generic arguments that handle cases involving _FloatN / _FloatNx types as specified in TS 18661-3 plus some defect fixes. C2x has further changes to the semantics for <tgmath.h> macros with such types, which should also be considered defect fixes (although handled through the integration of TS 18661-3 in C2x rather than through an issue tracking process). Specifically, the rules were changed because of problems raised with using the macros with the evaluation format types such as float_t and _Float32_t: the older version of the rules didn't allow passing _FloatN / _FloatNx types to the narrowing macros returning float or double, or passing float / double / long double to the narrowing macros returning _FloatN / _FloatNx, which was a problem with the evaluation format types which could be either kind of type depending on the value of FLT_EVAL_METHOD. Thus the new rules allow cases of mixing types which were not allowed before, and, as part of the changes, the handling of integer arguments was also changed: if there is any _FloatNx generic argument, integer generic arguments are treated as _Float32x (not double), while the rule about treating integer arguments to narrowing macros returning _FloatN or _FloatNx as _Float64 not double was removed (no longer needed now double is a valid argument to such macros). I've implemented the changes in GCC's __builtin_tgmath, which thus requires updates to glibc's test expectations so that the tests continue to build with GCC 13 (the test is also updated to test the argument types that weren't allowed before but are now valid under C2x rules). Given those test changes, it's then also necessary to fix the implementations in <tgmath.h> to have appropriate semantics with older GCC so that the tests pass with GCC versions before GCC 13 as well. For some cases (non-narrowing macros with two or three generic arguments; narrowing macros returning _Float32x), the older version of __builtin_tgmath doesn't correspond sufficiently well to C2x semantics, so in those cases <tgmath.h> is adjusted to use the older macro implementation instead of __builtin_tgmath. The older macro implementation is itself adjusted to give the desired semantics, with GCC 7 and later. (It's not possible to get the right semantics in all cases for the narrowing macros with GCC 6 and before when the _FloatN / _FloatNx names are typedefs rather than distinct types.) Tested as follows: with the full glibc testsuite for x86_64, GCC 6, 7, 11, 13; with execution of the math/tests for aarch64, arm, powerpc and powerpc64le, GCC 6, 7, 12 and 13 (powerpc64le only with GCC 12 and 13); with build-many-glibcs.py with GCC 6, 7, 12 and 13. |
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README
This directory contains the sources of the GNU C Library. See the file "version.h" for what release version you have. The GNU C Library is the standard system C library for all GNU systems, and is an important part of what makes up a GNU system. It provides the system API for all programs written in C and C-compatible languages such as C++ and Objective C; the runtime facilities of other programming languages use the C library to access the underlying operating system. In GNU/Linux systems, the C library works with the Linux kernel to implement the operating system behavior seen by user applications. In GNU/Hurd systems, it works with a microkernel and Hurd servers. The GNU C Library implements much of the POSIX.1 functionality in the GNU/Hurd system, using configurations i[4567]86-*-gnu. When working with Linux kernels, this version of the GNU C Library requires Linux kernel version 3.2 or later. Also note that the shared version of the libgcc_s library must be installed for the pthread library to work correctly. The GNU C Library supports these configurations for using Linux kernels: aarch64*-*-linux-gnu alpha*-*-linux-gnu arc*-*-linux-gnu arm-*-linux-gnueabi csky-*-linux-gnuabiv2 hppa-*-linux-gnu i[4567]86-*-linux-gnu x86_64-*-linux-gnu Can build either x86_64 or x32 ia64-*-linux-gnu loongarch64-*-linux-gnu Hardware floating point, LE only. m68k-*-linux-gnu microblaze*-*-linux-gnu mips-*-linux-gnu mips64-*-linux-gnu or1k-*-linux-gnu powerpc-*-linux-gnu Hardware or software floating point, BE only. powerpc64*-*-linux-gnu Big-endian and little-endian. s390-*-linux-gnu s390x-*-linux-gnu riscv32-*-linux-gnu riscv64-*-linux-gnu sh[34]-*-linux-gnu sparc*-*-linux-gnu sparc64*-*-linux-gnu If you are interested in doing a port, please contact the glibc maintainers; see https://www.gnu.org/software/libc/ for more information. See the file INSTALL to find out how to configure, build, and install the GNU C Library. You might also consider reading the WWW pages for the C library at https://www.gnu.org/software/libc/. The GNU C Library is (almost) completely documented by the Texinfo manual found in the `manual/' subdirectory. The manual is still being updated and contains some known errors and omissions; we regret that we do not have the resources to work on the manual as much as we would like. For corrections to the manual, please file a bug in the `manual' component, following the bug-reporting instructions below. Please be sure to check the manual in the current development sources to see if your problem has already been corrected. Please see https://www.gnu.org/software/libc/bugs.html for bug reporting information. We are now using the Bugzilla system to track all bug reports. This web page gives detailed information on how to report bugs properly. The GNU C Library is free software. See the file COPYING.LIB for copying conditions, and LICENSES for notices about a few contributions that require these additional notices to be distributed. License copyright years may be listed using range notation, e.g., 1996-2015, indicating that every year in the range, inclusive, is a copyrightable year that would otherwise be listed individually.