1 /*
2  * Double-precision math error handling.
3  *
4  * Copyright (c) 2018-2023, Arm Limited.
5  * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
6  */
7 
8 #include "math_config.h"
9 
10 #if WANT_ERRNO
11 # include <errno.h>
12 /* NOINLINE reduces code size and avoids making math functions non-leaf
13    when the error handling is inlined.  */
14 NOINLINE static double
15 with_errno (double y, int e)
16 {
17   errno = e;
18   return y;
19 }
20 #else
21 # define with_errno(x, e) (x)
22 #endif
23 
24 /* NOINLINE reduces code size.  */
25 NOINLINE static double
26 xflow (uint32_t sign, double y)
27 {
28   y = eval_as_double (opt_barrier_double (sign ? -y : y) * y);
29   return with_errno (y, ERANGE);
30 }
31 
32 HIDDEN double
33 __math_uflow (uint32_t sign)
34 {
35   return xflow (sign, 0x1p-767);
36 }
37 
38 /* Underflows to zero in some non-nearest rounding mode, setting errno
39    is valid even if the result is non-zero, but in the subnormal range.  */
40 HIDDEN double
41 __math_may_uflow (uint32_t sign)
42 {
43   return xflow (sign, 0x1.8p-538);
44 }
45 
46 HIDDEN double
47 __math_oflow (uint32_t sign)
48 {
49   return xflow (sign, 0x1p769);
50 }
51 
52 HIDDEN double
53 __math_divzero (uint32_t sign)
54 {
55   double y = opt_barrier_double (sign ? -1.0 : 1.0) / 0.0;
56   return with_errno (y, ERANGE);
57 }
58 
59 HIDDEN double
60 __math_invalid (double x)
61 {
62   double y = (x - x) / (x - x);
63   return isnan (x) ? y : with_errno (y, EDOM);
64 }
65 
66 /* Check result and set errno if necessary.  */
67 
68 HIDDEN double
69 __math_check_uflow (double y)
70 {
71   return y == 0.0 ? with_errno (y, ERANGE) : y;
72 }
73 
74 HIDDEN double
75 __math_check_oflow (double y)
76 {
77   return isinf (y) ? with_errno (y, ERANGE) : y;
78 }
79