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0a2546cdaa
Various fmax and fmin function implementations mishandle sNaN arguments: (a) When both arguments are NaNs, the return value should be a qNaN, but sometimes it is an sNaN if at least one argument is an sNaN. (b) Under TS 18661-1 semantics, if either argument is an sNaN then the result should be a qNaN (whereas if one argument is a qNaN and the other is not a NaN, the result should be the non-NaN argument). Various implementations treat sNaNs like qNaNs here. This patch fixes the x86 and x86_64 versions (ignoring float and double for 32-bit x86 given the inability to reliably avoid the sNaN turning into a qNaN before it gets to the called function). Tests of sNaN inputs to these functions are added. Note on architecture versions I haven't changed for this issue: AArch64 already gets this right (it uses a hardware instruction with the correct semantics for both quiet and signaling NaNs) and does not need changes. It's possible Alpha, IA64, SPARC might need changes (this would be shown by the testsuite if so). Tested for x86_64 and x86 (both i686 and i586 builds, to cover the different x86 implementations). [BZ #20947] * sysdeps/i386/fpu/s_fmaxl.S (__fmaxl): Add the arguments when either is a signaling NaN. * sysdeps/i386/fpu/s_fminl.S (__fminl): Likewise. Make code follow fmaxl more closely. * sysdeps/i386/i686/fpu/s_fmaxl.S (__fmaxl): Add the arguments when either is a signaling NaN. * sysdeps/i386/i686/fpu/s_fminl.S (__fminl): Likewise. * sysdeps/x86_64/fpu/s_fmax.S (__fmax): Likewise. * sysdeps/x86_64/fpu/s_fmaxf.S (__fmaxf): Likewise. * sysdeps/x86_64/fpu/s_fmaxl.S (__fmaxl): Likewise. * sysdeps/x86_64/fpu/s_fmin.S (__fmin): Likewise. * sysdeps/x86_64/fpu/s_fminf.S (__fminf): Likewise. * sysdeps/x86_64/fpu/s_fminl.S (__fminl): Likewise. * math/libm-test.inc (fmax_test_data): Add tests of sNaN inputs. (fmin_test_data): Likewise.
72 lines
1.6 KiB
ArmAsm
72 lines
1.6 KiB
ArmAsm
/* Compute minimum of two numbers, regarding NaN as missing argument.
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Copyright (C) 1997-2016 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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.text
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ENTRY(__fminl)
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fldt 16(%esp) // y
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fxam
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fnstsw
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fldt 4(%esp) // y : x
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andb $0x45, %ah
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cmpb $0x01, %ah
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je 2f // y == NaN
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fxam
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fnstsw
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andb $0x45, %ah
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cmpb $0x01, %ah
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je 3f // x == NaN
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fucom %st(1)
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fnstsw
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sahf
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jc 1f
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fxch %st(1)
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1: fstp %st(1)
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ret
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2: // st(1) is a NaN; st(0) may or may not be.
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fxam
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fnstsw
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andb $0x45, %ah
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cmpb $0x01, %ah
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je 4f
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// st(1) is a NaN; st(0) is not. Test if st(1) is signaling.
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testb $0x40, 23(%esp)
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jz 4f
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fstp %st(1)
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ret
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3: // st(0) is a NaN; st(1) is not. Test if st(0) is signaling.
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testb $0x40, 11(%esp)
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jz 4f
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fstp %st(0)
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ret
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4: // Both arguments are NaNs, or one is a signaling NaN.
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faddp
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ret
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END(__fminl)
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weak_alias (__fminl, fminl)
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