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// Copyright 2022 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/crc/internal/crc_memcpy.h"
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <limits>
#include <memory>
#include <string>
#include <utility>
#include "gtest/gtest.h"
#include "absl/crc/crc32c.h"
#include "absl/memory/memory.h"
#include "absl/random/distributions.h"
#include "absl/random/random.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/string_view.h"
namespace {
enum CrcEngine {
X86 = 0,
NONTEMPORAL = 1,
FALLBACK = 2,
};
// Correctness tests:
// - Every source/destination byte alignment 0-15, every size 0-511 bytes
// - Arbitrarily aligned source, large size
template <size_t max_size>
class CrcMemcpyTest : public testing::Test {
protected:
CrcMemcpyTest() {
source_ = std::make_unique<char[]>(kSize);
destination_ = std::make_unique<char[]>(kSize);
}
static constexpr size_t kAlignment = 16;
static constexpr size_t kMaxCopySize = max_size;
static constexpr size_t kSize = kAlignment + kMaxCopySize;
std::unique_ptr<char[]> source_;
std::unique_ptr<char[]> destination_;
absl::BitGen gen_;
};
// Small test is slightly larger 4096 bytes to allow coverage of the "large"
// copy function. The minimum size to exercise all code paths in that function
// would be around 256 consecutive tests (getting every possible tail value
// and 0-2 small copy loops after the main block), so testing from 4096-4500
// will cover all of those code paths multiple times.
typedef CrcMemcpyTest<4500> CrcSmallTest;
typedef CrcMemcpyTest<(1 << 24)> CrcLargeTest;
// Parametrize the small test so that it can be done with all configurations.
template <typename ParamsT>
class x86ParamTestTemplate : public CrcSmallTest,
public ::testing::WithParamInterface<ParamsT> {
protected:
x86ParamTestTemplate() {
if (GetParam().crc_engine_selector == FALLBACK) {
engine_ = std::make_unique<absl::crc_internal::FallbackCrcMemcpyEngine>();
} else if (GetParam().crc_engine_selector == NONTEMPORAL) {
engine_ =
std::make_unique<absl::crc_internal::CrcNonTemporalMemcpyEngine>();
} else {
engine_ = absl::crc_internal::CrcMemcpy::GetTestEngine(
GetParam().vector_lanes, GetParam().integer_lanes);
}
}
// Convenience method.
ParamsT GetParam() const {
return ::testing::WithParamInterface<ParamsT>::GetParam();
}
std::unique_ptr<absl::crc_internal::CrcMemcpyEngine> engine_;
};
struct TestParams {
CrcEngine crc_engine_selector = X86;
int vector_lanes = 0;
int integer_lanes = 0;
};
using x86ParamTest = x86ParamTestTemplate<TestParams>;
// SmallCorrectness is designed to exercise every possible set of code paths
// in the memcpy code, not including the loop.
TEST_P(x86ParamTest, SmallCorrectnessCheckSourceAlignment) {
constexpr size_t kTestSizes[] = {0, 100, 255, 512, 1024, 4000, kMaxCopySize};
for (size_t source_alignment = 0; source_alignment < kAlignment;
source_alignment++) {
for (auto size : kTestSizes) {
char* base_data = static_cast<char*>(source_.get()) + source_alignment;
for (size_t i = 0; i < size; i++) {
*(base_data + i) =
static_cast<char>(absl::Uniform<unsigned char>(gen_));
}
absl::crc32c_t initial_crc =
absl::crc32c_t{absl::Uniform<uint32_t>(gen_)};
absl::crc32c_t experiment_crc =
engine_->Compute(destination_.get(), source_.get() + source_alignment,
size, initial_crc);
// Check the memory region to make sure it is the same
int mem_comparison =
memcmp(destination_.get(), source_.get() + source_alignment, size);
SCOPED_TRACE(absl::StrCat("Error in memcpy of size: ", size,
" with source alignment: ", source_alignment));
ASSERT_EQ(mem_comparison, 0);
absl::crc32c_t baseline_crc = absl::ExtendCrc32c(
initial_crc,
absl::string_view(
static_cast<char*>(source_.get()) + source_alignment, size));
ASSERT_EQ(baseline_crc, experiment_crc);
}
}
}
TEST_P(x86ParamTest, SmallCorrectnessCheckDestAlignment) {
constexpr size_t kTestSizes[] = {0, 100, 255, 512, 1024, 4000, kMaxCopySize};
for (size_t dest_alignment = 0; dest_alignment < kAlignment;
dest_alignment++) {
for (auto size : kTestSizes) {
char* base_data = static_cast<char*>(source_.get());
for (size_t i = 0; i < size; i++) {
*(base_data + i) =
static_cast<char>(absl::Uniform<unsigned char>(gen_));
}
absl::crc32c_t initial_crc =
absl::crc32c_t{absl::Uniform<uint32_t>(gen_)};
absl::crc32c_t experiment_crc =
engine_->Compute(destination_.get() + dest_alignment, source_.get(),
size, initial_crc);
// Check the memory region to make sure it is the same
int mem_comparison =
memcmp(destination_.get() + dest_alignment, source_.get(), size);
SCOPED_TRACE(absl::StrCat("Error in memcpy of size: ", size,
" with dest alignment: ", dest_alignment));
ASSERT_EQ(mem_comparison, 0);
absl::crc32c_t baseline_crc = absl::ExtendCrc32c(
initial_crc,
absl::string_view(static_cast<char*>(source_.get()), size));
ASSERT_EQ(baseline_crc, experiment_crc);
}
}
}
INSTANTIATE_TEST_SUITE_P(x86ParamTest, x86ParamTest,
::testing::Values(
// Tests for configurations that may occur in prod.
TestParams{X86, 3, 0}, TestParams{X86, 1, 2},
// Fallback test.
TestParams{FALLBACK, 0, 0},
// Non Temporal
TestParams{NONTEMPORAL, 0, 0}));
} // namespace
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