8e7241fdde
Rebuilding (after touching certain files) is crazy slow because includes are out of control. Many of these files we need to rebuild are cctests which pull in more includes than they need. BUG=v8:5294 Review-Url: https://codereview.chromium.org/2304553002 Cr-Commit-Position: refs/heads/master@{#39080}
177 lines
6.1 KiB
C++
177 lines
6.1 KiB
C++
// Copyright 2013 the V8 project authors. All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following
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// disclaimer in the documentation and/or other materials provided
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// with the distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "src/flags.h"
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#include "src/isolate.h"
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#include "src/v8.h"
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#include "test/cctest/cctest.h"
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#include "src/base/utils/random-number-generator.h"
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using namespace v8::internal;
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static const int64_t kRandomSeeds[] = {-1, 1, 42, 100, 1234567890, 987654321};
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TEST(RandomSeedFlagIsUsed) {
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for (unsigned n = 0; n < arraysize(kRandomSeeds); ++n) {
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FLAG_random_seed = static_cast<int>(kRandomSeeds[n]);
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v8::Isolate::CreateParams create_params;
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create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
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v8::Isolate* i = v8::Isolate::New(create_params);
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v8::base::RandomNumberGenerator& rng =
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*reinterpret_cast<Isolate*>(i)->random_number_generator();
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CHECK_EQ(kRandomSeeds[n], rng.initial_seed());
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i->Dispose();
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}
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}
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// Chi squared for getting m 0s out of n bits.
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double ChiSquared(int m, int n) {
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double ys_minus_np1 = (m - n / 2.0);
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double chi_squared_1 = ys_minus_np1 * ys_minus_np1 * 2.0 / n;
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double ys_minus_np2 = ((n - m) - n / 2.0);
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double chi_squared_2 = ys_minus_np2 * ys_minus_np2 * 2.0 / n;
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return chi_squared_1 + chi_squared_2;
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}
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// Test for correlations between recent bits from the PRNG, or bits that are
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// biased.
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void RandomBitCorrelation(int random_bit) {
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FLAG_random_seed = 31415926;
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v8::Isolate::CreateParams create_params;
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create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
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v8::Isolate* isolate = v8::Isolate::New(create_params);
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Isolate* i_isolate = reinterpret_cast<Isolate*>(isolate);
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v8::base::RandomNumberGenerator* rng = i_isolate->random_number_generator();
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#ifdef DEBUG
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const int kHistory = 2;
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const int kRepeats = 1000;
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#else
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const int kHistory = 8;
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const int kRepeats = 10000;
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#endif
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uint32_t history[kHistory];
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// The predictor bit is either constant 0 or 1, or one of the bits from the
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// history.
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for (int predictor_bit = -2; predictor_bit < 32; predictor_bit++) {
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// The predicted bit is one of the bits from the PRNG.
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for (int ago = 0; ago < kHistory; ago++) {
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// We don't want to check whether each bit predicts itself.
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if (ago == 0 && predictor_bit == random_bit) continue;
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// Enter the new random value into the history
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for (int i = ago; i >= 0; i--) {
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history[i] = bit_cast<uint32_t>(rng->NextInt());
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}
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// Find out how many of the bits are the same as the prediction bit.
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int m = 0;
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for (int i = 0; i < kRepeats; i++) {
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v8::HandleScope scope(isolate);
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uint32_t random = bit_cast<uint32_t>(rng->NextInt());
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for (int j = ago - 1; j >= 0; j--) history[j + 1] = history[j];
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history[0] = random;
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int predicted;
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if (predictor_bit >= 0) {
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predicted = (history[ago] >> predictor_bit) & 1;
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} else {
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predicted = predictor_bit == -2 ? 0 : 1;
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}
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int bit = (random >> random_bit) & 1;
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if (bit == predicted) m++;
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}
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// Chi squared analysis for k = 2 (2, states: same/not-same) and one
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// degree of freedom (k - 1).
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double chi_squared = ChiSquared(m, kRepeats);
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if (chi_squared > 24) {
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int percent = static_cast<int>(m * 100.0 / kRepeats);
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if (predictor_bit < 0) {
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PrintF("Bit %d is %d %d%% of the time\n", random_bit,
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predictor_bit == -2 ? 0 : 1, percent);
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} else {
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PrintF("Bit %d is the same as bit %d %d ago %d%% of the time\n",
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random_bit, predictor_bit, ago, percent);
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}
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}
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// For 1 degree of freedom this corresponds to 1 in a million. We are
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// running ~8000 tests, so that would be surprising.
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CHECK(chi_squared <= 24);
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// If the predictor bit is a fixed 0 or 1 then it makes no sense to
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// repeat the test with a different age.
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if (predictor_bit < 0) break;
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}
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}
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isolate->Dispose();
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}
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#define TEST_RANDOM_BIT(BIT) \
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TEST(RandomBitCorrelations##BIT) { RandomBitCorrelation(BIT); }
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TEST_RANDOM_BIT(0)
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TEST_RANDOM_BIT(1)
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TEST_RANDOM_BIT(2)
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TEST_RANDOM_BIT(3)
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TEST_RANDOM_BIT(4)
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TEST_RANDOM_BIT(5)
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TEST_RANDOM_BIT(6)
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TEST_RANDOM_BIT(7)
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TEST_RANDOM_BIT(8)
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TEST_RANDOM_BIT(9)
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TEST_RANDOM_BIT(10)
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TEST_RANDOM_BIT(11)
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TEST_RANDOM_BIT(12)
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TEST_RANDOM_BIT(13)
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TEST_RANDOM_BIT(14)
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TEST_RANDOM_BIT(15)
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TEST_RANDOM_BIT(16)
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TEST_RANDOM_BIT(17)
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TEST_RANDOM_BIT(18)
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TEST_RANDOM_BIT(19)
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TEST_RANDOM_BIT(20)
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TEST_RANDOM_BIT(21)
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TEST_RANDOM_BIT(22)
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TEST_RANDOM_BIT(23)
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TEST_RANDOM_BIT(24)
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TEST_RANDOM_BIT(25)
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TEST_RANDOM_BIT(26)
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TEST_RANDOM_BIT(27)
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TEST_RANDOM_BIT(28)
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TEST_RANDOM_BIT(29)
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TEST_RANDOM_BIT(30)
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TEST_RANDOM_BIT(31)
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#undef TEST_RANDOM_BIT
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