1 //===-- Unittests for x86 long double -------------------------------------===//
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 #include "src/__support/FPUtil/FPBits.h"
10 #include "utils/UnitTest/Test.h"
11
12 #include <math.h>
13
14 using FPBits = __llvm_libc::fputil::FPBits<long double>;
15
TEST(X86LongDoubleTest,is_nan)16 TEST(X86LongDoubleTest, is_nan) {
17 // In the nan checks below, we use the macro isnan from math.h to ensure that
18 // a number is actually a NaN. The isnan macro resolves to the compiler
19 // builtin function. Hence, matching LLVM-libc's notion of NaN with the
20 // isnan result ensures that LLVM-libc's behavior matches the compiler's
21 // behavior.
22
23 FPBits bits(0.0l);
24 bits.exponent = FPBits::MAX_EXPONENT;
25 for (unsigned int i = 0; i < 1000000; ++i) {
26 // If exponent has the max value and the implicit bit is 0,
27 // then the number is a NaN for all values of mantissa.
28 bits.mantissa = i;
29 long double nan = bits;
30 ASSERT_NE(isnan(nan), 0);
31 ASSERT_TRUE(bits.is_nan());
32 }
33
34 bits.implicitBit = 1;
35 for (unsigned int i = 1; i < 1000000; ++i) {
36 // If exponent has the max value and the implicit bit is 1,
37 // then the number is a NaN for all non-zero values of mantissa.
38 // Note the initial value of |i| of 1 to avoid a zero mantissa.
39 bits.mantissa = i;
40 long double nan = bits;
41 ASSERT_NE(isnan(nan), 0);
42 ASSERT_TRUE(bits.is_nan());
43 }
44
45 bits.exponent = 1;
46 bits.implicitBit = 0;
47 for (unsigned int i = 0; i < 1000000; ++i) {
48 // If exponent is non-zero and also not max, and the implicit bit is 0,
49 // then the number is a NaN for all values of mantissa.
50 bits.mantissa = i;
51 long double nan = bits;
52 ASSERT_NE(isnan(nan), 0);
53 ASSERT_TRUE(bits.is_nan());
54 }
55
56 bits.exponent = 1;
57 bits.implicitBit = 1;
58 for (unsigned int i = 0; i < 1000000; ++i) {
59 // If exponent is non-zero and also not max, and the implicit bit is 1,
60 // then the number is normal value for all values of mantissa.
61 bits.mantissa = i;
62 long double valid = bits;
63 ASSERT_EQ(isnan(valid), 0);
64 ASSERT_FALSE(bits.is_nan());
65 }
66
67 bits.exponent = 0;
68 bits.implicitBit = 1;
69 for (unsigned int i = 0; i < 1000000; ++i) {
70 // If exponent is zero, then the number is a valid but denormal value.
71 bits.mantissa = i;
72 long double valid = bits;
73 ASSERT_EQ(isnan(valid), 0);
74 ASSERT_FALSE(bits.is_nan());
75 }
76
77 bits.exponent = 0;
78 bits.implicitBit = 0;
79 for (unsigned int i = 0; i < 1000000; ++i) {
80 // If exponent is zero, then the number is a valid but denormal value.
81 bits.mantissa = i;
82 long double valid = bits;
83 ASSERT_EQ(isnan(valid), 0);
84 ASSERT_FALSE(bits.is_nan());
85 }
86 }
87