dense-to-sparse.js

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// |jit-test| allow-oom

// Appending elements to a dense array should make the array sparse when the

// length exceeds the limit.

function test() {

  const MAX_DENSE_ELEMENTS_ALLOCATION = (1 << 28) - 1;

  const VALUES_PER_HEADER = 2;

  const MAX_DENSE_ELEMENTS_COUNT = MAX_DENSE_ELEMENTS_ALLOCATION - VALUES_PER_HEADER;

  const SPARSE_DENSITY_RATIO = 8;

  const MIN_DENSE = MAX_DENSE_ELEMENTS_COUNT / SPARSE_DENSITY_RATIO;

  const MARGIN = 16;

  let a = [];

  // Fill the beginning of array to make it keep dense until length exceeds

  // MAX_DENSE_ELEMENTS_COUNT.

  for (let i = 0; i < MIN_DENSE; i++)

    a[i] = i;

  // Skip from MIN_DENSE to MAX_DENSE_ELEMENTS_COUNT - MARGIN, to reduce the

  // time taken by test.

  // Fill the ending of array to make it sparse at MAX_DENSE_ELEMENTS_COUNT.

  for (let i = MAX_DENSE_ELEMENTS_COUNT - MARGIN; i < MAX_DENSE_ELEMENTS_COUNT + MARGIN; i++)

    a[i] = i;

  // Make sure the last element is defined.

  assertEq(a.length, MAX_DENSE_ELEMENTS_COUNT + MARGIN);

  assertEq(a[a.length - 1], MAX_DENSE_ELEMENTS_COUNT + MARGIN - 1);

  // Make sure elements around MAX_DENSE_ELEMENTS_COUNT are also defined.

  assertEq(a[MAX_DENSE_ELEMENTS_COUNT - 1], MAX_DENSE_ELEMENTS_COUNT - 1);

  assertEq(a[MAX_DENSE_ELEMENTS_COUNT], MAX_DENSE_ELEMENTS_COUNT);

  assertEq(a[MAX_DENSE_ELEMENTS_COUNT + 1], MAX_DENSE_ELEMENTS_COUNT + 1);

// Takes too long time on debug build.

if (!getBuildConfiguration("debug")) {

  test();