1//===-- Check exceptions for exp functions ----------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLVM_LIBC_SRC___SUPPORT_MATH_CHECK_EXP_EXCEPTIONS_H
10#define LLVM_LIBC_SRC___SUPPORT_MATH_CHECK_EXP_EXCEPTIONS_H
11
12#include "hdr/fenv_macros.h"
13#include "src/__support/FPUtil/FPBits.h"
14#include "src/__support/common.h"
15#include "src/__support/macros/config.h"
16
17namespace LIBC_NAMESPACE_DECL {
18
19namespace math {
20
21namespace check {
22
23namespace exp_internal {
24
25template <typename T> struct Bounds;
26
27template <> struct Bounds<float> {
28 // Smallest value that will cause overflow, generated from Sollya:
29 // > float_max = 2^127 * (2 - 2^-23);
30 // > upper = round(log(float_max), SG, RU);
31 // > printfloat(upper);
32 static constexpr float UPPER = 0x1.62e43p6f;
33 static constexpr uint32_t UPPER_BITS = 0x42b1'7218;
34 // Largest value that will cause underflow, generated from Sollya:
35 // > float_min = 2^-126;
36 // > lower = round(log(float_min), SG, RD);
37 // > printfloat(lower);
38 static constexpr float LOWER = -0x1.5d58ap6f;
39 static constexpr uint32_t LOWER_BITS = 0xc2ae'ac50;
40};
41
42template <> struct Bounds<double> {
43 // Smallest value that will cause overflow, generated from Sollya:
44 // > double_max = 2^1023 * (2 - 2^-52);
45 // > upper = round(log(double_max), D, RU);
46 // > printdouble(upper);
47 static constexpr double UPPER = 0x1.62e42fefa39fp9;
48 static constexpr uint64_t UPPER_BITS = 0x4086'2e42'fefa'39f0;
49 // Largest value that will cause underflow, generated from Sollya:
50 // > double_min = 2^-1022;
51 // > lower = round(log(double_min), D, RD);
52 // > printfloat(lower);
53 static constexpr double LOWER = -0x1.6232bdd7abcd3p9;
54 static constexpr uint64_t LOWER_BITS = 0xc086'232b'dd7a'bcd3;
55};
56
57} // namespace exp_internal
58
59template <typename T> LIBC_INLINE int exp_exceptions(T x, int rounding_mode) {
60 using FPBits = typename fputil::FPBits<T>;
61 using StorageType = typename FPBits::StorageType;
62
63 FPBits x_bits(x);
64 if (x_bits.is_signaling_nan())
65 return FE_INVALID;
66 if (x_bits.is_inf_or_nan() || x_bits.is_zero())
67 return 0;
68 StorageType x_u = x_bits.uintval();
69 if (x_u >= exp_internal::Bounds<T>::UPPER_BITS && x_bits.is_pos())
70 return (rounding_mode == FE_TONEAREST || rounding_mode == FE_UPWARD)
71 ? (FE_OVERFLOW | FE_INEXACT)
72 : FE_INEXACT;
73 if (x_u >= exp_internal::Bounds<T>::LOWER_BITS)
74 return FE_UNDERFLOW | FE_INEXACT;
75 return FE_INEXACT;
76}
77
78} // namespace check
79
80} // namespace math
81
82} // namespace LIBC_NAMESPACE_DECL
83
84#endif // LLVM_LIBC_SRC___SUPPORT_MATH_CHECK_EXP_EXCEPTIONS_H
85