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This patch fixes bug 16356, bad results from x86 / x86_64 expl / exp10l in directed rounding modes, the most serious of the bugs shown up by my patch expanding libm test coverage. When I fixed bug 16293, I thought it was only necessary to set round-to-nearest when using frndint in expm1 functions, because in other cases the cancellation error from having the resulting fractional part close to 1 or -1 would not be significant. However, in expl and exp10l, the way the final fractional part gets computed (something more complicated than a simple subtraction, because more precision is needed than you'd get that way) can result in a value outside the range [-1, 1] when the argument to frndint was very close to an integer and was rounded the "wrong" way because of the rounding mode - and the f2xm1 instruction has undefined results if its argument is outside [-1, 1], so resulting in the large errors seen. So this patch removes the USE_AS_EXPM1L conditionals on the round-to-nearest settings, so all of expl, expm1l and exp10l now get round-to-nearest used for frndint (meaning the final fractional part can at most be slightly above 0.5 in magnitude). Associated tests of exp and exp10 are added and testing of exp10 in directed rounding modes enabled. Tested x86_64 and x86 and ulps updated accordingly. * sysdeps/i386/fpu/e_expl.S (IEEE754_EXPL): Also set round-to-nearest for [!USE_AS_EXPM1L]. * sysdeps/x86_64/fpu/e_expl.S (IEEE754_EXPL): Likewise. * math/auto-libm-test-in: Do not expect cosh tests to fail. Add more tests of exp and exp10. Expect some exp10 tests to miss exceptions or fail in directed rounding modes. * math/auto-libm-test-out: Regenerated. * math/libm-test.inc (exp10_tonearest_test_data): New array. (exp10_test_tonearest): New function. (exp10_towardzero_test_data): New array. (exp10_test_towardzero): New function. (exp10_downward_test_data): New array. (exp10_test_downward): New function. (exp10_upward_test_data): New array. (exp10_test_upward): New function. (main): Call the new functions. * sysdeps/i386/fpu/libm-test-ulps: Update. * sysdeps/x86_64/fpu/libm-test-ulps: Likewise. |
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| WUR-REPORT | ||
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. The current GNU/Hurd support requires out-of-tree patches that will eventually be incorporated into an official GNU C Library release. When working with Linux kernels, this version of the GNU C Library requires Linux kernel version 2.6.16 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: i[4567]86-*-linux-gnu x86_64-*-linux-gnu Can build either x86_64 or x32 powerpc-*-linux-gnu Hardware or software floating point, BE only. powerpc64*-*-linux-gnu Big-endian and little-endian. s390-*-linux-gnu s390x-*-linux-gnu sh[34]-*-linux-gnu sparc*-*-linux-gnu sparc64*-*-linux-gnu The code for other CPU configurations supported by volunteers outside of the core glibc maintenance effort is contained in the `ports' add-on, located in the `ports' subdirectory of the source tree. aarch64*-*-linux-gnu alpha*-*-linux-gnu am33*-*-linux-gnu Not currently functional arm-*-linux-gnueabi hppa-*-linux-gnu Not currently functional without patches. ia64-*-linux-gnu m68k-*-linux-gnu mips-*-linux-gnu mips64-*-linux-gnu tilegx-*-linux-gnu tilepro-*-linux-gnu If you are interested in doing a port, please contact the glibc maintainers; see http://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 http://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 http://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., 2000-2013, indicating that every year in the range, inclusive, is a copyrightable year that would otherwise be listed individually.