--- /dev/null
+//===-- Unittests for x86 long double -------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "include/math.h"
+#include "utils/FPUtil/FPBits.h"
+#include "utils/UnitTest/Test.h"
+
+using FPBits = __llvm_libc::fputil::FPBits<long double>;
+
+TEST(X86LongDoubleTest, isNaN) {
+ // In the nan checks below, we use the macro isnan from math.h to ensure that
+ // a number is actually a NaN. The isnan macro resolves to the compiler
+ // builtin function. Hence, matching LLVM-libc's notion of NaN with the
+ // isnan result ensures that LLVM-libc's behavior matches the compiler's
+ // behavior.
+
+ FPBits bits(0.0l);
+ bits.exponent = FPBits::maxExponent;
+ for (unsigned int i = 0; i < 1000000; ++i) {
+ // If exponent has the max value and the implicit bit is 0,
+ // then the number is a NaN for all values of mantissa.
+ bits.mantissa = i;
+ long double nan = bits;
+ ASSERT_NE(isnan(nan), 0);
+ ASSERT_TRUE(bits.isNaN());
+ }
+
+ bits.implicitBit = 1;
+ for (unsigned int i = 1; i < 1000000; ++i) {
+ // If exponent has the max value and the implicit bit is 1,
+ // then the number is a NaN for all non-zero values of mantissa.
+ // Note the initial value of |i| of 1 to avoid a zero mantissa.
+ bits.mantissa = i;
+ long double nan = bits;
+ ASSERT_NE(isnan(nan), 0);
+ ASSERT_TRUE(bits.isNaN());
+ }
+
+ bits.exponent = 1;
+ bits.implicitBit = 0;
+ for (unsigned int i = 0; i < 1000000; ++i) {
+ // If exponent is non-zero and also not max, and the implicit bit is 0,
+ // then the number is a NaN for all values of mantissa.
+ bits.mantissa = i;
+ long double nan = bits;
+ ASSERT_NE(isnan(nan), 0);
+ ASSERT_TRUE(bits.isNaN());
+ }
+
+ bits.exponent = 1;
+ bits.implicitBit = 1;
+ for (unsigned int i = 0; i < 1000000; ++i) {
+ // If exponent is non-zero and also not max, and the implicit bit is 1,
+ // then the number is normal value for all values of mantissa.
+ bits.mantissa = i;
+ long double valid = bits;
+ ASSERT_EQ(isnan(valid), 0);
+ ASSERT_FALSE(bits.isNaN());
+ }
+
+ bits.exponent = 0;
+ bits.implicitBit = 1;
+ for (unsigned int i = 0; i < 1000000; ++i) {
+ // If exponent is zero, then the number is a valid but denormal value.
+ bits.mantissa = i;
+ long double valid = bits;
+ ASSERT_EQ(isnan(valid), 0);
+ ASSERT_FALSE(bits.isNaN());
+ }
+
+ bits.exponent = 0;
+ bits.implicitBit = 0;
+ for (unsigned int i = 0; i < 1000000; ++i) {
+ // If exponent is zero, then the number is a valid but denormal value.
+ bits.mantissa = i;
+ long double valid = bits;
+ ASSERT_EQ(isnan(valid), 0);
+ ASSERT_FALSE(bits.isNaN());
+ }
+}