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 "test/UnitTest/Test.h" 11 12 #include "hdr/math_macros.h" 13 14 using FPBits = LIBC_NAMESPACE::fputil::FPBits<long double>; 15 16 TEST(LlvmLibcX86LongDoubleTest, 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 constexpr uint32_t COUNT = 100'000; 23 24 FPBits bits(0.0l); 25 bits.set_biased_exponent(FPBits::MAX_BIASED_EXPONENT); 26 for (unsigned int i = 0; i < COUNT; ++i) { 27 // If exponent has the max value and the implicit bit is 0, 28 // then the number is a NaN for all values of mantissa. 29 bits.set_mantissa(i); 30 ASSERT_TRUE(bits.is_nan()); 31 } 32 33 bits.set_implicit_bit(1); 34 for (unsigned int i = 1; i < COUNT; ++i) { 35 // If exponent has the max value and the implicit bit is 1, 36 // then the number is a NaN for all non-zero values of mantissa. 37 // Note the initial value of |i| of 1 to avoid a zero mantissa. 38 bits.set_mantissa(i); 39 ASSERT_TRUE(bits.is_nan()); 40 } 41 42 bits.set_biased_exponent(1); 43 bits.set_implicit_bit(0); 44 for (unsigned int i = 0; i < COUNT; ++i) { 45 // If exponent is non-zero and also not max, and the implicit bit is 0, 46 // then the number is a NaN for all values of mantissa. 47 bits.set_mantissa(i); 48 ASSERT_TRUE(bits.is_nan()); 49 } 50 51 bits.set_biased_exponent(1); 52 bits.set_implicit_bit(1); 53 for (unsigned int i = 0; i < COUNT; ++i) { 54 // If exponent is non-zero and also not max, and the implicit bit is 1, 55 // then the number is normal value for all values of mantissa. 56 bits.set_mantissa(i); 57 ASSERT_FALSE(bits.is_nan()); 58 } 59 60 bits.set_biased_exponent(0); 61 bits.set_implicit_bit(1); 62 for (unsigned int i = 0; i < COUNT; ++i) { 63 // If exponent is zero, then the number is a valid but denormal value. 64 bits.set_mantissa(i); 65 ASSERT_FALSE(bits.is_nan()); 66 } 67 68 bits.set_biased_exponent(0); 69 bits.set_implicit_bit(0); 70 for (unsigned int i = 0; i < COUNT; ++i) { 71 // If exponent is zero, then the number is a valid but denormal value. 72 bits.set_mantissa(i); 73 ASSERT_FALSE(bits.is_nan()); 74 } 75 } 76