diff options
Diffstat (limited to 'absl/random/internal')
| -rw-r--r-- | absl/random/internal/BUILD.bazel | 27 | ||||
| -rw-r--r-- | absl/random/internal/distribution_impl.h | 66 | ||||
| -rw-r--r-- | absl/random/internal/distribution_impl_test.cc | 42 | ||||
| -rw-r--r-- | absl/random/internal/wide_multiply.h | 109 | ||||
| -rw-r--r-- | absl/random/internal/wide_multiply_test.cc | 66 |
5 files changed, 202 insertions, 108 deletions
diff --git a/absl/random/internal/BUILD.bazel b/absl/random/internal/BUILD.bazel index cd50982d8b36..ec58cecd43e9 100644 --- a/absl/random/internal/BUILD.bazel +++ b/absl/random/internal/BUILD.bazel @@ -201,6 +201,19 @@ cc_library( ) cc_library( + name = "wide_multiply", + hdrs = ["wide_multiply.h"], + copts = ABSL_DEFAULT_COPTS, + linkopts = ABSL_DEFAULT_LINKOPTS, + deps = [ + ":traits", + "//absl/base:bits", + "//absl/base:config", + "//absl/numeric:int128", + ], +) + +cc_library( name = "nonsecure_base", hdrs = ["nonsecure_base.h"], copts = ABSL_DEFAULT_COPTS, @@ -598,6 +611,20 @@ cc_test( ], ) +cc_test( + name = "wide_multiply_test", + size = "small", + srcs = ["wide_multiply_test.cc"], + copts = ABSL_TEST_COPTS, + linkopts = ABSL_DEFAULT_LINKOPTS, + deps = [ + ":wide_multiply", + "//absl/base:bits", + "//absl/numeric:int128", + "@com_google_googletest//:gtest_main", + ], +) + cc_library( name = "nanobenchmark", srcs = ["nanobenchmark.cc"], diff --git a/absl/random/internal/distribution_impl.h b/absl/random/internal/distribution_impl.h index 9b6ffb0fb504..49b3e1a6e33d 100644 --- a/absl/random/internal/distribution_impl.h +++ b/absl/random/internal/distribution_impl.h @@ -188,72 +188,6 @@ struct RandU64ToReal<float> { } }; -inline uint128 MultiplyU64ToU128(uint64_t a, uint64_t b) { -#if defined(ABSL_HAVE_INTRINSIC_INT128) - return uint128(static_cast<__uint128_t>(a) * b); -#elif defined(ABSL_INTERNAL_USE_UMUL128) - // uint64_t * uint64_t => uint128 multiply using imul intrinsic on MSVC. - uint64_t high = 0; - const uint64_t low = _umul128(a, b, &high); - return absl::MakeUint128(high, low); -#else - // uint128(a) * uint128(b) in emulated mode computes a full 128-bit x 128-bit - // multiply. However there are many cases where that is not necessary, and it - // is only necessary to support a 64-bit x 64-bit = 128-bit multiply. This is - // for those cases. - const uint64_t a00 = static_cast<uint32_t>(a); - const uint64_t a32 = a >> 32; - const uint64_t b00 = static_cast<uint32_t>(b); - const uint64_t b32 = b >> 32; - - const uint64_t c00 = a00 * b00; - const uint64_t c32a = a00 * b32; - const uint64_t c32b = a32 * b00; - const uint64_t c64 = a32 * b32; - - const uint32_t carry = - static_cast<uint32_t>(((c00 >> 32) + static_cast<uint32_t>(c32a) + - static_cast<uint32_t>(c32b)) >> - 32); - - return absl::MakeUint128(c64 + (c32a >> 32) + (c32b >> 32) + carry, - c00 + (c32a << 32) + (c32b << 32)); -#endif -} - -// wide_multiply<T> multiplies two N-bit values to a 2N-bit result. -template <typename UIntType> -struct wide_multiply { - static constexpr size_t kN = std::numeric_limits<UIntType>::digits; - using input_type = UIntType; - using result_type = typename random_internal::unsigned_bits<kN * 2>::type; - - static result_type multiply(input_type a, input_type b) { - return static_cast<result_type>(a) * b; - } - - static input_type hi(result_type r) { return r >> kN; } - static input_type lo(result_type r) { return r; } - - static_assert(std::is_unsigned<UIntType>::value, - "Class-template wide_multiply<> argument must be unsigned."); -}; - -#ifndef ABSL_HAVE_INTRINSIC_INT128 -template <> -struct wide_multiply<uint64_t> { - using input_type = uint64_t; - using result_type = uint128; - - static result_type multiply(uint64_t a, uint64_t b) { - return MultiplyU64ToU128(a, b); - } - - static uint64_t hi(result_type r) { return Uint128High64(r); } - static uint64_t lo(result_type r) { return Uint128Low64(r); } -}; -#endif - } // namespace random_internal } // namespace absl diff --git a/absl/random/internal/distribution_impl_test.cc b/absl/random/internal/distribution_impl_test.cc index 09e7a318ccc5..fcc169046d7e 100644 --- a/absl/random/internal/distribution_impl_test.cc +++ b/absl/random/internal/distribution_impl_test.cc @@ -461,46 +461,4 @@ TEST(DistributionImplTest, ExhaustiveFloat) { } } -TEST(DistributionImplTest, MultiplyU64ToU128Test) { - using absl::random_internal::MultiplyU64ToU128; - constexpr uint64_t k1 = 1; - constexpr uint64_t kMax = ~static_cast<uint64_t>(0); - - EXPECT_EQ(absl::uint128(0), MultiplyU64ToU128(0, 0)); - - // Max uint64 - EXPECT_EQ(MultiplyU64ToU128(kMax, kMax), - absl::MakeUint128(0xfffffffffffffffe, 0x0000000000000001)); - EXPECT_EQ(absl::MakeUint128(0, kMax), MultiplyU64ToU128(kMax, 1)); - EXPECT_EQ(absl::MakeUint128(0, kMax), MultiplyU64ToU128(1, kMax)); - for (int i = 0; i < 64; ++i) { - EXPECT_EQ(absl::MakeUint128(0, kMax) << i, - MultiplyU64ToU128(kMax, k1 << i)); - EXPECT_EQ(absl::MakeUint128(0, kMax) << i, - MultiplyU64ToU128(k1 << i, kMax)); - } - - // 1-bit x 1-bit. - for (int i = 0; i < 64; ++i) { - for (int j = 0; j < 64; ++j) { - EXPECT_EQ(absl::MakeUint128(0, 1) << (i + j), - MultiplyU64ToU128(k1 << i, k1 << j)); - EXPECT_EQ(absl::MakeUint128(0, 1) << (i + j), - MultiplyU64ToU128(k1 << i, k1 << j)); - } - } - - // Verified multiplies - EXPECT_EQ(MultiplyU64ToU128(0xffffeeeeddddcccc, 0xbbbbaaaa99998888), - absl::MakeUint128(0xbbbb9e2692c5dddc, 0xc28f7531048d2c60)); - EXPECT_EQ(MultiplyU64ToU128(0x0123456789abcdef, 0xfedcba9876543210), - absl::MakeUint128(0x0121fa00ad77d742, 0x2236d88fe5618cf0)); - EXPECT_EQ(MultiplyU64ToU128(0x0123456789abcdef, 0xfdb97531eca86420), - absl::MakeUint128(0x0120ae99d26725fc, 0xce197f0ecac319e0)); - EXPECT_EQ(MultiplyU64ToU128(0x97a87f4f261ba3f2, 0xfedcba9876543210), - absl::MakeUint128(0x96fbf1a8ae78d0ba, 0x5a6dd4b71f278320)); - EXPECT_EQ(MultiplyU64ToU128(0xfedcba9876543210, 0xfdb97531eca86420), - absl::MakeUint128(0xfc98c6981a413e22, 0x342d0bbf48948200)); -} - } // namespace diff --git a/absl/random/internal/wide_multiply.h b/absl/random/internal/wide_multiply.h new file mode 100644 index 000000000000..ebbfa1f2c10e --- /dev/null +++ b/absl/random/internal/wide_multiply.h @@ -0,0 +1,109 @@ +// Copyright 2017 The Abseil Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +#ifndef ABSL_RANDOM_INTERNAL_WIDE_MULTIPLY_H_ +#define ABSL_RANDOM_INTERNAL_WIDE_MULTIPLY_H_ + +#include <cstdint> +#include <limits> +#include <type_traits> + +#if (defined(_WIN32) || defined(_WIN64)) && defined(_M_IA64) +#include <intrin.h> // NOLINT(build/include_order) +#pragma intrinsic(_umul128) +#define ABSL_INTERNAL_USE_UMUL128 1 +#endif + +#include "absl/base/config.h" +#include "absl/base/internal/bits.h" +#include "absl/numeric/int128.h" +#include "absl/random/internal/traits.h" + +namespace absl { +namespace random_internal { + +// Helper object to multiply two 64-bit values to a 128-bit value. +// MultiplyU64ToU128 multiplies two 64-bit values to a 128-bit value. +// If an intrinsic is available, it is used, otherwise use native 32-bit +// multiplies to construct the result. +inline uint128 MultiplyU64ToU128(uint64_t a, uint64_t b) { +#if defined(ABSL_HAVE_INTRINSIC_INT128) + return uint128(static_cast<__uint128_t>(a) * b); +#elif defined(ABSL_INTERNAL_USE_UMUL128) + // uint64_t * uint64_t => uint128 multiply using imul intrinsic on MSVC. + uint64_t high = 0; + const uint64_t low = _umul128(a, b, &high); + return absl::MakeUint128(high, low); +#else + // uint128(a) * uint128(b) in emulated mode computes a full 128-bit x 128-bit + // multiply. However there are many cases where that is not necessary, and it + // is only necessary to support a 64-bit x 64-bit = 128-bit multiply. This is + // for those cases. + const uint64_t a00 = static_cast<uint32_t>(a); + const uint64_t a32 = a >> 32; + const uint64_t b00 = static_cast<uint32_t>(b); + const uint64_t b32 = b >> 32; + + const uint64_t c00 = a00 * b00; + const uint64_t c32a = a00 * b32; + const uint64_t c32b = a32 * b00; + const uint64_t c64 = a32 * b32; + + const uint32_t carry = + static_cast<uint32_t>(((c00 >> 32) + static_cast<uint32_t>(c32a) + + static_cast<uint32_t>(c32b)) >> + 32); + + return absl::MakeUint128(c64 + (c32a >> 32) + (c32b >> 32) + carry, + c00 + (c32a << 32) + (c32b << 32)); +#endif +} + +// wide_multiply<T> multiplies two N-bit values to a 2N-bit result. +template <typename UIntType> +struct wide_multiply { + static constexpr size_t kN = std::numeric_limits<UIntType>::digits; + using input_type = UIntType; + using result_type = typename random_internal::unsigned_bits<kN * 2>::type; + + static result_type multiply(input_type a, input_type b) { + return static_cast<result_type>(a) * b; + } + + static input_type hi(result_type r) { return r >> kN; } + static input_type lo(result_type r) { return r; } + + static_assert(std::is_unsigned<UIntType>::value, + "Class-template wide_multiply<> argument must be unsigned."); +}; + +#ifndef ABSL_HAVE_INTRINSIC_INT128 +template <> +struct wide_multiply<uint64_t> { + using input_type = uint64_t; + using result_type = uint128; + + static result_type multiply(uint64_t a, uint64_t b) { + return MultiplyU64ToU128(a, b); + } + + static uint64_t hi(result_type r) { return Uint128High64(r); } + static uint64_t lo(result_type r) { return Uint128Low64(r); } +}; +#endif + +} // namespace random_internal +} // namespace absl + +#endif // ABSL_RANDOM_INTERNAL_WIDE_MULTIPLY_H_ diff --git a/absl/random/internal/wide_multiply_test.cc b/absl/random/internal/wide_multiply_test.cc new file mode 100644 index 000000000000..922603f22629 --- /dev/null +++ b/absl/random/internal/wide_multiply_test.cc @@ -0,0 +1,66 @@ +// Copyright 2017 The Abseil Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +#include "absl/random/internal/wide_multiply.h" + +#include "gtest/gtest.h" +#include "absl/base/internal/bits.h" +#include "absl/numeric/int128.h" + +using absl::random_internal::MultiplyU64ToU128; + +namespace { + +TEST(WideMultiplyTest, MultiplyU64ToU128Test) { + constexpr uint64_t k1 = 1; + constexpr uint64_t kMax = ~static_cast<uint64_t>(0); + + EXPECT_EQ(absl::uint128(0), MultiplyU64ToU128(0, 0)); + + // Max uint64 + EXPECT_EQ(MultiplyU64ToU128(kMax, kMax), + absl::MakeUint128(0xfffffffffffffffe, 0x0000000000000001)); + EXPECT_EQ(absl::MakeUint128(0, kMax), MultiplyU64ToU128(kMax, 1)); + EXPECT_EQ(absl::MakeUint128(0, kMax), MultiplyU64ToU128(1, kMax)); + for (int i = 0; i < 64; ++i) { + EXPECT_EQ(absl::MakeUint128(0, kMax) << i, + MultiplyU64ToU128(kMax, k1 << i)); + EXPECT_EQ(absl::MakeUint128(0, kMax) << i, + MultiplyU64ToU128(k1 << i, kMax)); + } + + // 1-bit x 1-bit. + for (int i = 0; i < 64; ++i) { + for (int j = 0; j < 64; ++j) { + EXPECT_EQ(absl::MakeUint128(0, 1) << (i + j), + MultiplyU64ToU128(k1 << i, k1 << j)); + EXPECT_EQ(absl::MakeUint128(0, 1) << (i + j), + MultiplyU64ToU128(k1 << i, k1 << j)); + } + } + + // Verified multiplies + EXPECT_EQ(MultiplyU64ToU128(0xffffeeeeddddcccc, 0xbbbbaaaa99998888), + absl::MakeUint128(0xbbbb9e2692c5dddc, 0xc28f7531048d2c60)); + EXPECT_EQ(MultiplyU64ToU128(0x0123456789abcdef, 0xfedcba9876543210), + absl::MakeUint128(0x0121fa00ad77d742, 0x2236d88fe5618cf0)); + EXPECT_EQ(MultiplyU64ToU128(0x0123456789abcdef, 0xfdb97531eca86420), + absl::MakeUint128(0x0120ae99d26725fc, 0xce197f0ecac319e0)); + EXPECT_EQ(MultiplyU64ToU128(0x97a87f4f261ba3f2, 0xfedcba9876543210), + absl::MakeUint128(0x96fbf1a8ae78d0ba, 0x5a6dd4b71f278320)); + EXPECT_EQ(MultiplyU64ToU128(0xfedcba9876543210, 0xfdb97531eca86420), + absl::MakeUint128(0xfc98c6981a413e22, 0x342d0bbf48948200)); +} + +} // namespace |