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97a58d885b
If feenableexcept or fedisableexcept gets excepts=FE_INVALID=0x80 as input, we have a signed left shift: 0x80 << 24 which is not representable as int and thus is undefined behaviour according to C standard. This patch casts excepts as unsigned int before shifting, which is defined. For me, the observed undefined behaviour is that the shift is done with "unsigned"-instructions, which is exactly what we want. Furthermore, I don't get any exception-flags. After the fix, the code is using the same instruction sequence as before.
35 lines
1.2 KiB
C
35 lines
1.2 KiB
C
/* Enable floating-point exceptions.
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Copyright (C) 2000-2023 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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#include <fpu_control.h>
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int
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feenableexcept (int excepts)
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{
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fexcept_t temp, old_exc, new_flags;
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_FPU_GETCW (temp);
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old_exc = (temp & FPC_EXCEPTION_MASK) >> FPC_EXCEPTION_MASK_SHIFT;
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new_flags = (temp | (((unsigned int) excepts & FE_ALL_EXCEPT)
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<< FPC_EXCEPTION_MASK_SHIFT));
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_FPU_SETCW (new_flags);
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return old_exc;
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}
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