test/hotspot/gtest/utilities/test_count_trailing_zeros.cpp

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#include "precompiled.hpp"
#include "utilities/count_trailing_zeros.hpp"
#include "utilities/globalDefinitions.hpp"
#include "unittest.hpp"

TEST(count_trailing_zeros, one_or_two_set_bits) {
  unsigned i = 0;               // Position of a set bit.
  for (uintx ix = 1; ix != 0; ix <<= 1, ++i) {
    unsigned j = 0;             // Position of a set bit.
    for (uintx jx = 1; jx != 0; jx <<= 1, ++j) {
      uintx value = ix | jx;
      EXPECT_EQ(MIN2(i, j), count_trailing_zeros(value))
        << "value = " << value;
    }
  }
}

TEST(count_trailing_zeros, all_ones_followed_by_all_zeros) {
  unsigned i = BitsPerWord - 1; // Index of most significant set bit.
  uintx value = ~(uintx)0;
  for ( ; value != 0; value >>= 1, --i) {
    EXPECT_EQ(0u, count_trailing_zeros(value))
      << "value = " << value;
  }
}

TEST(count_trailing_zeros, all_zeros_followed_by_all_ones) {
  unsigned i = 0;               // Index of least significant set bit.
  uintx value = ~(uintx)0;
  for ( ; value != 0; value <<= 1, ++i) {
    EXPECT_EQ(i, count_trailing_zeros(value))
      << "value = " << value;
  }
}