ee89927707
Implement double precision FMA (Fused Multiply-Add) for targets without FMA instructions using __uint128_t to store the intermediate results. Reviewed By: michaelrj, sivachandra Differential Revision: https://reviews.llvm.org/D124495
100 lines
3.8 KiB
C++
100 lines
3.8 KiB
C++
//===-- Utility class to test different flavors of fma --------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_TEST_SRC_MATH_FMATEST_H
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#define LLVM_LIBC_TEST_SRC_MATH_FMATEST_H
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#include "src/__support/FPUtil/FPBits.h"
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#include "utils/MPFRWrapper/MPFRUtils.h"
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#include "utils/UnitTest/FPMatcher.h"
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#include "utils/UnitTest/Test.h"
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#include "utils/testutils/RandUtils.h"
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namespace mpfr = __llvm_libc::testing::mpfr;
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template <typename T>
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class FmaTestTemplate : public __llvm_libc::testing::Test {
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private:
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using Func = T (*)(T, T, T);
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using FPBits = __llvm_libc::fputil::FPBits<T>;
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using UIntType = typename FPBits::UIntType;
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const T nan = T(__llvm_libc::fputil::FPBits<T>::build_nan(1));
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const T inf = T(__llvm_libc::fputil::FPBits<T>::inf());
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const T neg_inf = T(__llvm_libc::fputil::FPBits<T>::neg_inf());
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const T zero = T(__llvm_libc::fputil::FPBits<T>::zero());
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const T neg_zero = T(__llvm_libc::fputil::FPBits<T>::neg_zero());
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UIntType get_random_bit_pattern() {
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UIntType bits{0};
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for (UIntType i = 0; i < sizeof(UIntType) / 2; ++i) {
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bits =
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(bits << 2) + static_cast<uint16_t>(__llvm_libc::testutils::rand());
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}
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return bits;
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}
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public:
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void test_special_numbers(Func func) {
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EXPECT_FP_EQ(func(zero, zero, zero), zero);
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EXPECT_FP_EQ(func(zero, neg_zero, neg_zero), neg_zero);
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EXPECT_FP_EQ(func(inf, inf, zero), inf);
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EXPECT_FP_EQ(func(neg_inf, inf, neg_inf), neg_inf);
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EXPECT_FP_EQ(func(inf, zero, zero), nan);
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EXPECT_FP_EQ(func(inf, neg_inf, inf), nan);
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EXPECT_FP_EQ(func(nan, zero, inf), nan);
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EXPECT_FP_EQ(func(inf, neg_inf, nan), nan);
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// Test underflow rounding up.
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EXPECT_FP_EQ(func(T(0.5), T(FPBits(FPBits::MIN_SUBNORMAL)),
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T(FPBits(FPBits::MIN_SUBNORMAL))),
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T(FPBits(UIntType(2))));
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// Test underflow rounding down.
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T v = T(FPBits(FPBits::MIN_NORMAL + UIntType(1)));
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EXPECT_FP_EQ(func(T(1) / T(FPBits::MIN_NORMAL << 1), v,
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T(FPBits(FPBits::MIN_NORMAL))),
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v);
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// Test overflow.
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T z = T(FPBits(FPBits::MAX_NORMAL));
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EXPECT_FP_EQ(func(T(1.75), z, -z), T(0.75) * z);
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// Exact cancellation.
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EXPECT_FP_EQ(func(T(3.0), T(5.0), -T(15.0)), T(0.0));
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EXPECT_FP_EQ(func(T(-3.0), T(5.0), T(15.0)), T(0.0));
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}
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void test_subnormal_range(Func func) {
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constexpr UIntType COUNT = 1000001;
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constexpr UIntType STEP =
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(FPBits::MAX_SUBNORMAL - FPBits::MIN_SUBNORMAL) / COUNT;
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for (UIntType v = FPBits::MIN_SUBNORMAL, w = FPBits::MAX_SUBNORMAL;
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v <= FPBits::MAX_SUBNORMAL && w >= FPBits::MIN_SUBNORMAL;
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v += STEP, w -= STEP) {
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T x = T(FPBits(get_random_bit_pattern())), y = T(FPBits(v)),
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z = T(FPBits(w));
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mpfr::TernaryInput<T> input{x, y, z};
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ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Fma, input, func(x, y, z),
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0.5);
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}
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}
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void test_normal_range(Func func) {
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constexpr UIntType COUNT = 1000001;
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constexpr UIntType STEP = (FPBits::MAX_NORMAL - FPBits::MIN_NORMAL) / COUNT;
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for (UIntType v = FPBits::MIN_NORMAL, w = FPBits::MAX_NORMAL;
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v <= FPBits::MAX_NORMAL && w >= FPBits::MIN_NORMAL;
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v += STEP, w -= STEP) {
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T x = T(FPBits(v)), y = T(FPBits(w)),
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z = T(FPBits(get_random_bit_pattern()));
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mpfr::TernaryInput<T> input{x, y, z};
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ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Fma, input, func(x, y, z),
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0.5);
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}
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}
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};
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#endif // LLVM_LIBC_TEST_SRC_MATH_FMATEST_H
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