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//===-- Utility class to test different flavors of ldexp --------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIBC_TEST_SRC_MATH_LDEXPTEST_H
#define LLVM_LIBC_TEST_SRC_MATH_LDEXPTEST_H
#include "src/__support/CPP/limits.h" // INT_MAX
#include "src/__support/FPUtil/FPBits.h"
#include "src/__support/FPUtil/NormalFloat.h"
#include "test/UnitTest/FEnvSafeTest.h"
#include "test/UnitTest/FPMatcher.h"
#include "test/UnitTest/Test.h"
#include "hdr/math_macros.h"
#include <stdint.h>
template <typename T>
class LdExpTestTemplate : public LIBC_NAMESPACE::testing::FEnvSafeTest {
using FPBits = LIBC_NAMESPACE::fputil::FPBits<T>;
using NormalFloat = LIBC_NAMESPACE::fputil::NormalFloat<T>;
using StorageType = typename FPBits::StorageType;
const T inf = FPBits::inf(Sign::POS).get_val();
const T neg_inf = FPBits::inf(Sign::NEG).get_val();
const T zero = FPBits::zero(Sign::POS).get_val();
const T neg_zero = FPBits::zero(Sign::NEG).get_val();
const T nan = FPBits::quiet_nan().get_val();
// A normalized mantissa to be used with tests.
static constexpr StorageType MANTISSA = NormalFloat::ONE + 0x1234;
public:
typedef T (*LdExpFunc)(T, int);
void testSpecialNumbers(LdExpFunc func) {
int exp_array[5] = {-INT_MAX - 1, -10, 0, 10, INT_MAX};
for (int exp : exp_array) {
ASSERT_FP_EQ(zero, func(zero, exp));
ASSERT_FP_EQ(neg_zero, func(neg_zero, exp));
ASSERT_FP_EQ(inf, func(inf, exp));
ASSERT_FP_EQ(neg_inf, func(neg_inf, exp));
ASSERT_FP_EQ(nan, func(nan, exp));
}
}
void testPowersOfTwo(LdExpFunc func) {
int32_t exp_array[5] = {1, 2, 3, 4, 5};
int32_t val_array[6] = {1, 2, 4, 8, 16, 32};
for (int32_t exp : exp_array) {
for (int32_t val : val_array) {
ASSERT_FP_EQ(T(val << exp), func(T(val), exp));
ASSERT_FP_EQ(T(-1 * (val << exp)), func(T(-val), exp));
}
}
}
void testOverflow(LdExpFunc func) {
NormalFloat x(Sign::POS, FPBits::MAX_BIASED_EXPONENT - 10,
NormalFloat::ONE + 0xF00BA);
for (int32_t exp = 10; exp < 100; ++exp) {
ASSERT_FP_EQ(inf, func(T(x), exp));
ASSERT_FP_EQ(neg_inf, func(-T(x), exp));
}
}
void testUnderflowToZeroOnNormal(LdExpFunc func) {
// In this test, we pass a normal nubmer to func and expect zero
// to be returned due to underflow.
int32_t base_exponent = FPBits::EXP_BIAS + FPBits::FRACTION_LEN;
int32_t exp_array[] = {base_exponent + 5, base_exponent + 4,
base_exponent + 3, base_exponent + 2,
base_exponent + 1};
T x = NormalFloat(Sign::POS, 0, MANTISSA);
for (int32_t exp : exp_array) {
ASSERT_FP_EQ(func(x, -exp), x > 0 ? zero : neg_zero);
}
}
void testUnderflowToZeroOnSubnormal(LdExpFunc func) {
// In this test, we pass a normal nubmer to func and expect zero
// to be returned due to underflow.
int32_t base_exponent = FPBits::EXP_BIAS + FPBits::FRACTION_LEN;
int32_t exp_array[] = {base_exponent + 5, base_exponent + 4,
base_exponent + 3, base_exponent + 2,
base_exponent + 1};
T x = NormalFloat(Sign::POS, -FPBits::EXP_BIAS, MANTISSA);
for (int32_t exp : exp_array) {
ASSERT_FP_EQ(func(x, -exp), x > 0 ? zero : neg_zero);
}
}
void testNormalOperation(LdExpFunc func) {
T val_array[] = {// Normal numbers
NormalFloat(Sign::POS, 100, MANTISSA),
NormalFloat(Sign::POS, -100, MANTISSA),
NormalFloat(Sign::NEG, 100, MANTISSA),
NormalFloat(Sign::NEG, -100, MANTISSA),
// Subnormal numbers
NormalFloat(Sign::POS, -FPBits::EXP_BIAS, MANTISSA),
NormalFloat(Sign::NEG, -FPBits::EXP_BIAS, MANTISSA)};
for (int32_t exp = 0; exp <= FPBits::FRACTION_LEN; ++exp) {
for (T x : val_array) {
// We compare the result of ldexp with the result
// of the native multiplication/division instruction.
// We need to use a NormalFloat here (instead of 1 << exp), because
// there are 32 bit systems that don't support 128bit long ints but
// support long doubles. This test can do 1 << 64, which would fail
// in these systems.
NormalFloat two_to_exp = NormalFloat(static_cast<T>(1.L));
two_to_exp = two_to_exp.mul2(exp);
ASSERT_FP_EQ(func(x, exp), x * two_to_exp);
ASSERT_FP_EQ(func(x, -exp), x / two_to_exp);
}
}
// Normal which trigger mantissa overflow.
T x = NormalFloat(Sign::POS, -FPBits::EXP_BIAS + 1,
StorageType(2) * NormalFloat::ONE - StorageType(1));
ASSERT_FP_EQ(func(x, -1), x / 2);
ASSERT_FP_EQ(func(-x, -1), -x / 2);
// Start with a normal number high exponent but pass a very low number for
// exp. The result should be a subnormal number.
x = NormalFloat(Sign::POS, FPBits::EXP_BIAS, NormalFloat::ONE);
int exp = -FPBits::MAX_BIASED_EXPONENT - 5;
T result = func(x, exp);
FPBits result_bits(result);
ASSERT_FALSE(result_bits.is_zero());
// Verify that the result is indeed subnormal.
ASSERT_EQ(result_bits.get_biased_exponent(), uint16_t(0));
// But if the exp is so less that normalization leads to zero, then
// the result should be zero.
result = func(x, -FPBits::MAX_BIASED_EXPONENT - FPBits::FRACTION_LEN - 5);
ASSERT_TRUE(FPBits(result).is_zero());
// Start with a subnormal number but pass a very high number for exponent.
// The result should not be infinity.
x = NormalFloat(Sign::POS, -FPBits::EXP_BIAS + 1, NormalFloat::ONE >> 10);
exp = FPBits::MAX_BIASED_EXPONENT + 5;
ASSERT_FALSE(FPBits(func(x, exp)).is_inf());
// But if the exp is large enough to oversome than the normalization shift,
// then it should result in infinity.
exp = FPBits::MAX_BIASED_EXPONENT + 15;
ASSERT_FP_EQ(func(x, exp), inf);
}
};
#define LIST_LDEXP_TESTS(T, func) \
using LlvmLibcLdExpTest = LdExpTestTemplate<T>; \
TEST_F(LlvmLibcLdExpTest, SpecialNumbers) { testSpecialNumbers(&func); } \
TEST_F(LlvmLibcLdExpTest, PowersOfTwo) { testPowersOfTwo(&func); } \
TEST_F(LlvmLibcLdExpTest, OverFlow) { testOverflow(&func); } \
TEST_F(LlvmLibcLdExpTest, UnderflowToZeroOnNormal) { \
testUnderflowToZeroOnNormal(&func); \
} \
TEST_F(LlvmLibcLdExpTest, UnderflowToZeroOnSubnormal) { \
testUnderflowToZeroOnSubnormal(&func); \
} \
TEST_F(LlvmLibcLdExpTest, NormalOperation) { testNormalOperation(&func); }
#endif // LLVM_LIBC_TEST_SRC_MATH_LDEXPTEST_H
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