compiler/leb128_encoder_test.cc

/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * 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
 *
 *      http://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 "base/histogram-inl.h"
#include "common_test.h"
#include "leb128.h"
#include "leb128_encoder.h"

namespace art {

class Leb128Test : public CommonTest {};

struct DecodeUnsignedLeb128TestCase {
  uint32_t decoded;
  uint8_t leb128_data[5];
};

static DecodeUnsignedLeb128TestCase uleb128_tests[] = {
    {0,          {0, 0, 0, 0, 0}},
    {1,          {1, 0, 0, 0, 0}},
    {0x7F,       {0x7F, 0, 0, 0, 0}},
    {0x80,       {0x80, 1, 0, 0, 0}},
    {0x81,       {0x81, 1, 0, 0, 0}},
    {0xFF,       {0xFF, 1, 0, 0, 0}},
    {0x4000,     {0x80, 0x80, 1, 0, 0}},
    {0x4001,     {0x81, 0x80, 1, 0, 0}},
    {0x4081,     {0x81, 0x81, 1, 0, 0}},
    {0x0FFFFFFF, {0xFF, 0xFF, 0xFF, 0x7F, 0}},
    {0xFFFFFFFF, {0xFF, 0xFF, 0xFF, 0xFF, 0xF}},
};

TEST_F(Leb128Test, Singles) {
  // Test individual encodings.
  for (size_t i = 0; i < arraysize(uleb128_tests); ++i) {
    UnsignedLeb128EncodingVector builder;
    builder.PushBack(uleb128_tests[i].decoded);
    const uint8_t* data_ptr = &uleb128_tests[i].leb128_data[0];
    const uint8_t* encoded_data_ptr = &builder.GetData()[0];
    for (size_t j = 0; j < 5; ++j) {
      if (j < builder.GetData().size()) {
        EXPECT_EQ(data_ptr[j], encoded_data_ptr[j]) << " i = " << i << " j = " << j;
      } else {
        EXPECT_EQ(data_ptr[j], 0U) << " i = " << i << " j = " << j;
      }
    }
    EXPECT_EQ(DecodeUnsignedLeb128(&data_ptr), uleb128_tests[i].decoded) << " i = " << i;
  }
}

TEST_F(Leb128Test, Stream) {
  // Encode a number of entries.
  UnsignedLeb128EncodingVector builder;
  for (size_t i = 0; i < arraysize(uleb128_tests); ++i) {
    builder.PushBack(uleb128_tests[i].decoded);
  }
  const uint8_t* encoded_data_ptr = &builder.GetData()[0];
  for (size_t i = 0; i < arraysize(uleb128_tests); ++i) {
    const uint8_t* data_ptr = &uleb128_tests[i].leb128_data[0];
    for (size_t j = 0; j < 5; ++j) {
      if (data_ptr[j] != 0) {
        EXPECT_EQ(data_ptr[j], encoded_data_ptr[j]) << " i = " << i << " j = " << j;
      }
    }
    EXPECT_EQ(DecodeUnsignedLeb128(&encoded_data_ptr), uleb128_tests[i].decoded) << " i = " << i;
  }
}

TEST_F(Leb128Test, Speed) {
  UniquePtr<Histogram<uint64_t> > enc_hist(new Histogram<uint64_t>("Leb128EncodeSpeedTest", 5));
  UniquePtr<Histogram<uint64_t> > dec_hist(new Histogram<uint64_t>("Leb128DecodeSpeedTest", 5));
  UnsignedLeb128EncodingVector builder;
  // Push back 1024 chunks of 1024 values measuring encoding speed.
  uint64_t last_time = NanoTime();
  for (size_t i = 0; i < 1024; i++) {
    for (size_t j = 0; j < 1024; j++) {
      builder.PushBack((i * 1024) + j);
    }
    uint64_t cur_time = NanoTime();
    enc_hist->AddValue(cur_time - last_time);
    last_time = cur_time;
  }
  // Verify encoding and measure decode speed.
  const uint8_t* encoded_data_ptr = &builder.GetData()[0];
  last_time = NanoTime();
  for (size_t i = 0; i < 1024; i++) {
    for (size_t j = 0; j < 1024; j++) {
      EXPECT_EQ(DecodeUnsignedLeb128(&encoded_data_ptr), (i * 1024) + j);
    }
    uint64_t cur_time = NanoTime();
    dec_hist->AddValue(cur_time - last_time);
    last_time = cur_time;
  }

  Histogram<uint64_t>::CumulativeData enc_data;
  enc_hist->CreateHistogram(&enc_data);
  enc_hist->PrintConfidenceIntervals(std::cout, 0.99, enc_data);

  Histogram<uint64_t>::CumulativeData dec_data;
  dec_hist->CreateHistogram(&dec_data);
  dec_hist->PrintConfidenceIntervals(std::cout, 0.99, dec_data);
}

}  // namespace art