mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-09 23:00:07 +00:00
0cc0033ef1
According to the specification of ISO/IEC TS 18661-1:2014, The strfromd, strfromf, and strfroml functions are equivalent to snprintf(s, n, format, fp) (7.21.6.5), except the format string contains only the character %, an optional precision that does not contain an asterisk *, and one of the conversion specifiers a, A, e, E, f, F, g, or G, which applies to the type (double, float, or long double) indicated by the function suffix (rather than by a length modifier). Use of these functions with any other 20 format string results in undefined behavior. strfromf will convert the arguement with type float to double first. According to the latest version of IEEE754 which is published in 2019, Conversion of a quiet NaN from a narrower format to a wider format in the same radix, and then back to the same narrower format, should not change the quiet NaN payload in any way except to make it canonical. When either an input or result is a NaN, this standard does not interpret the sign of a NaN. However, operations on bit strings—copy, negate, abs, copySign—specify the sign bit of a NaN result, sometimes based upon the sign bit of a NaN operand. The logical predicates totalOrder and isSignMinus are also affected by the sign bit of a NaN operand. For all other operations, this standard does not specify the sign bit of a NaN result, even when there is only one input NaN, or when the NaN is produced from an invalid operation. converting NAN or -NAN with type float to double doesn't need to keep the signbit. As a result, this test case isn't mandatory. The problem is that according to RISC-V ISA manual in chapter 11.3 of riscv-isa-20191213, Except when otherwise stated, if the result of a floating-point operation is NaN, it is the canonical NaN. The canonical NaN has a positive sign and all significand bits clear except the MSB, a.k.a. the quiet bit. For single-precision floating-point, this corresponds to the pattern 0x7fc00000. which means that conversion -NAN from float to double won't keep the signbit. Since glibc ought to be consistent here between types and architectures, this patch adds copysign to fix this problem if the string is NAN. This patch adds two different functions under sysdeps directory to work around the issue. This patch has been tested on x86_64 and riscv64. Resolves: BZ #29501 v2: Change from macros to different inline functions. v3: Add unlikely check to isnan. v4: Fix wrong commit message header. v5: Fix style: add space before parentheses. v6: Add copyright. Signed-off-by: Letu Ren <fantasquex@gmail.com> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> |
||
|---|---|---|
| argp | ||
| assert | ||
| benchtests | ||
| bits | ||
| catgets | ||
| ChangeLog.old | ||
| conform | ||
| crypt | ||
| csu | ||
| ctype | ||
| debug | ||
| dirent | ||
| dlfcn | ||
| elf | ||
| gmon | ||
| gnulib | ||
| grp | ||
| gshadow | ||
| hesiod | ||
| htl | ||
| hurd | ||
| iconv | ||
| iconvdata | ||
| include | ||
| inet | ||
| intl | ||
| io | ||
| libio | ||
| locale | ||
| localedata | ||
| login | ||
| mach | ||
| malloc | ||
| manual | ||
| math | ||
| mathvec | ||
| misc | ||
| nis | ||
| nptl | ||
| nptl_db | ||
| nscd | ||
| nss | ||
| po | ||
| posix | ||
| pwd | ||
| resolv | ||
| resource | ||
| rt | ||
| scripts | ||
| setjmp | ||
| shadow | ||
| signal | ||
| socket | ||
| soft-fp | ||
| stdio-common | ||
| stdlib | ||
| string | ||
| sunrpc | ||
| support | ||
| sysdeps | ||
| sysvipc | ||
| termios | ||
| time | ||
| timezone | ||
| wcsmbs | ||
| wctype | ||
| .clang-format | ||
| .gitattributes | ||
| .gitignore | ||
| abi-tags | ||
| aclocal.m4 | ||
| config.h.in | ||
| config.make.in | ||
| configure | ||
| configure.ac | ||
| CONTRIBUTED-BY | ||
| COPYING | ||
| COPYING.LIB | ||
| extra-lib.mk | ||
| gen-locales.mk | ||
| INSTALL | ||
| libc-abis | ||
| libof-iterator.mk | ||
| LICENSES | ||
| MAINTAINERS | ||
| Makeconfig | ||
| Makefile | ||
| Makefile.help | ||
| Makefile.in | ||
| Makerules | ||
| NEWS | ||
| o-iterator.mk | ||
| README | ||
| Rules | ||
| SHARED-FILES | ||
| shlib-versions | ||
| test-skeleton.c | ||
| version.h | ||
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.