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C compilers may fold const values at compile time, so expressions which try to elicit underflow/overflow by performing simple arithemetic on suitable values will not generate the required exceptions. Work around this by replacing code which does these arithmetic operations with calls to the existing __math_xflow functions that are designed to do this correctly. Signed-off-by: Keith Packard <keithp@keithp.com> ---- v2: libm/math: Pass sign to __math_xflow instead of muliplying result
91 lines
2.7 KiB
C
91 lines
2.7 KiB
C
/* Single-precision math error handling.
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Copyright (c) 2017-2018 Arm Ltd. All rights reserved.
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SPDX-License-Identifier: BSD-3-Clause
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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1. Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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3. The name of the company may not be used to endorse or promote
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products derived from this software without specific prior written
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permission.
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THIS SOFTWARE IS PROVIDED BY ARM LTD ``AS IS'' AND ANY EXPRESS OR IMPLIED
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WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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IN NO EVENT SHALL ARM LTD BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
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#include "fdlibm.h"
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#include "math_config.h"
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#if WANT_ERRNO
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#include <errno.h>
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/* NOINLINE reduces code size and avoids making math functions non-leaf
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when the error handling is inlined. */
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NOINLINE static float
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with_errnof (float y, int e)
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{
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errno = e;
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return y;
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}
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#else
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#define with_errnof(x, e) (x)
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#endif
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/* NOINLINE prevents fenv semantics breaking optimizations. */
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NOINLINE static float
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xflowf (uint32_t sign, float y)
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{
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y = (sign ? -y : y) * y;
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return with_errnof (y, ERANGE);
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}
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HIDDEN float
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__math_uflowf (uint32_t sign)
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{
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return xflowf (sign, 0x1p-95f);
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}
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#if !__OBSOLETE_MATH
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#if WANT_ERRNO_UFLOW
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/* Underflows to zero in some non-nearest rounding mode, setting errno
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is valid even if the result is non-zero, but in the subnormal range. */
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HIDDEN float
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__math_may_uflowf (uint32_t sign)
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{
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return xflowf (sign, 0x1.4p-75f);
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}
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#endif
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#endif /* !__OBSOLETE_MATH */
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HIDDEN float
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__math_oflowf (uint32_t sign)
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{
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return xflowf (sign, 0x1p97f);
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}
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HIDDEN float
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__math_divzerof (uint32_t sign)
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{
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float y = 0;
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return with_errnof ((sign ? -1 : 1) / y, ERANGE);
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}
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HIDDEN float
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__math_invalidf (float x)
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{
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float y = (x - x) / (x - x);
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return isnan (x) ? y : with_errnof (y, EDOM);
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}
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