Revert of Add test to check PRNG quality.

test/cctest/test-random-number-generator.cc

Index: test/cctest/test-random-number-generator.cc
diff --git a/test/cctest/test-random-number-generator.cc b/test/cctest/test-random-number-generator.cc
index 9c15b69ecd4032ac77eb33dc1a1639dcff8c619f..f5e05cb39636353bf8022ad9015f89ed4b003919 100644
--- a/test/cctest/test-random-number-generator.cc
+++ b/test/cctest/test-random-number-generator.cc
@@ -51,89 +51,3 @@
     i->Dispose();
   }
 }
-
-
-// Chi squared for getting m 0s out of n bits.
-double ChiSquared(int m, int n) {
-  double ys_minus_np1 = (m - n / 2.0);
-  double chi_squared_1 = ys_minus_np1 * ys_minus_np1 * 2.0 / n;
-  double ys_minus_np2 = ((n - m) - n / 2.0);
-  double chi_squared_2 = ys_minus_np2 * ys_minus_np2 * 2.0 / n;
-  return chi_squared_1 + chi_squared_2;
-}
-
-
-// Test for correlations between recent bits from the PRNG, or bits that are
-// biased.
-TEST(RandomBitCorrelations) {
-  FLAG_random_seed = 31415926;
-  LocalContext env;
-  v8::Isolate* isolate = env->GetIsolate();
-  Isolate* i_isolate = reinterpret_cast<Isolate*>(isolate);
-  v8::base::RandomNumberGenerator* rng = i_isolate->random_number_generator();
-#ifdef DEBUG
-  const int kHistory = 2;
-  const int kRepeats = 1000;
-#else
-  const int kHistory = 8;
-  const int kRepeats = 10000;
-#endif
-  uint32_t history[kHistory];
-  // The predictor bit is either constant 0 or 1, or one of the bits from the
-  // history.
-  for (int predictor_bit = -2; predictor_bit < 32; predictor_bit++) {
-    // The predicted bit is one of the bits from the PRNG.
-    for (int random_bit = 0; random_bit < 32; random_bit++) {
-      // The predicted bit is taken from the previous output of the PRNG.
-      for (int ago = 0; ago < kHistory; ago++) {
-        // We don't want to check whether each bit predicts itself.
-        if (ago == 0 && predictor_bit == random_bit) continue;
-
-        // Enter the new random value into the history
-        for (int i = ago; i >= 0; i--) {
-          history[i] = bit_cast<uint32_t>(rng->NextInt());
-        }
-
-        // Find out how many of the bits are the same as the prediction bit.
-        int m = 0;
-        for (int i = 0; i < kRepeats; i++) {
-          v8::HandleScope scope(isolate);
-          uint32_t random = bit_cast<uint32_t>(rng->NextInt());
-          for (int j = ago - 1; j >= 0; j--) history[j + 1] = history[j];
-          history[0] = random;
-
-          int predicted;
-          if (predictor_bit >= 0) {
-            predicted = (history[ago] >> predictor_bit) & 1;
-          } else {
-            predicted = predictor_bit == -2 ? 0 : 1;
-          }
-          int bit = (random >> random_bit) & 1;
-          if (bit == predicted) m++;
-        }
-
-        // Chi squared analysis for k = 2 (2, states: same/not-same) and one
-        // degree of freedom (k - 1).
-        double chi_squared = ChiSquared(m, kRepeats);
-        if (chi_squared > 24) {
-          int percent = static_cast<int>(m * 100.0 / kRepeats);
-          if (predictor_bit < 0) {
-            PrintF("Bit %d is %d %d%% of the time\n", random_bit,
-                   predictor_bit == -2 ? 0 : 1, percent);
-          } else {
-            PrintF("Bit %d is the same as bit %d %d ago %d%% of the time\n",
-                   random_bit, predictor_bit, ago, percent);
-          }
-        }
-
-        // For 1 degree of freedom this corresponds to 1 in a million.  We are
-        // running ~8000 tests, so that would be surprising.
-        CHECK(chi_squared <= 24);
-
-        // If the predictor bit is a fixed 0 or 1 then it makes no sense to
-        // repeat the test with a different age.
-        if (predictor_bit < 0) break;
-      }
-    }
-  }
-}