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According to ISO C23 (7.6.4.4), fesetexcept is supposed to set floating-point exception flags without raising a trap (unlike feraiseexcept, which is supposed to raise a trap if feenableexcept was called with the appropriate argument). This is a side-effect of how we implement the GNU extension feenableexcept, where feenableexcept/fesetenv/fesetmode/feupdateenv might issue prctl (PR_SET_FPEXC, PR_FP_EXC_PRECISE) depending of the argument. And on PR_FP_EXC_PRECISE, setting a floating-point exception flag triggers a trap. To make the both functions follow the C23, fesetexcept and fesetexceptflag now fail if the argument may trigger a trap. The math tests now check for an value different than 0, instead of bail out as unsupported for EXCEPTION_SET_FORCES_TRAP. Checked on powerpc64le-linux-gnu. Reviewed-by: Carlos O'Donell <carlos@redhat.com>
71 lines
2.3 KiB
C
71 lines
2.3 KiB
C
/* Set floating-point environment exception handling.
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Copyright (C) 1997-2023 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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<https://www.gnu.org/licenses/>. */
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#include <fenv_libc.h>
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int
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__fesetexceptflag (const fexcept_t *flagp, int excepts)
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{
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fenv_union_t u, n;
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fexcept_t flag;
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/* Get the current state. */
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u.fenv = fegetenv_register ();
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/* Ignore exceptions not listed in 'excepts'. */
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flag = *flagp & excepts;
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/* Replace the exception status */
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int excepts_mask = FPSCR_STICKY_BITS & excepts;
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if ((excepts & FE_INVALID) != 0)
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excepts_mask |= FE_ALL_INVALID;
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n.l = ((u.l & ~excepts_mask)
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| (flag & FPSCR_STICKY_BITS)
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/* Turn FE_INVALID into FE_INVALID_SOFTWARE. */
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| (flag >> ((31 - FPSCR_VX) - (31 - FPSCR_VXSOFT))
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& FE_INVALID_SOFTWARE));
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/* Store the new status word (along with the rest of the environment).
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This may cause floating-point exceptions if the restored state
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requests it. */
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if (n.l != u.l)
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{
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if (n.l & fenv_exceptions_to_reg (excepts))
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/* Setting the exception flags may trigger a trap. ISO C 23 § 7.6.4.4
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does not allow it. */
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return -1;
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fesetenv_register (n.fenv);
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}
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/* Deal with FE_INVALID_SOFTWARE not being implemented on some chips. */
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if (flag & FE_INVALID)
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feraiseexcept(FE_INVALID);
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/* Success. */
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return 0;
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}
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#include <shlib-compat.h>
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#if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_2)
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strong_alias (__fesetexceptflag, __old_fesetexceptflag)
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compat_symbol (libm, __old_fesetexceptflag, fesetexceptflag, GLIBC_2_1);
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#endif
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versioned_symbol (libm, __fesetexceptflag, fesetexceptflag, GLIBC_2_2);
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