v8/test/mjsunit/array-literal-feedback.js

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// Flags: --allow-natives-syntax --smi-only-arrays --expose-gc
// Flags: --track-allocation-sites --noalways-opt

// Test element kind of objects.
// Since --smi-only-arrays affects builtins, its default setting at compile
// time sticks if built with snapshot.  If --smi-only-arrays is deactivated
// by default, only a no-snapshot build actually has smi-only arrays enabled
// in this test case.  Depending on whether smi-only arrays are actually
// enabled, this test takes the appropriate code path to check smi-only arrays.

// support_smi_only_arrays = %HasFastSmiElements(new Array(1,2,3,4,5,6,7,8));
support_smi_only_arrays = true;

if (support_smi_only_arrays) {
  print("Tests include smi-only arrays.");
} else {
  print("Tests do NOT include smi-only arrays.");
}

if (support_smi_only_arrays) {

  function get_literal(x) {
    var literal = [1, 2, x];
    return literal;
  }

  get_literal(3);
  get_literal(3);
  %OptimizeFunctionOnNextCall(get_literal);
  a = get_literal(3);
  assertOptimized(get_literal);
  assertTrue(%HasFastSmiElements(a));
  a[0] = 3.5;

  // We should have transitioned the boilerplate array to double, and
  // crankshafted code should de-opt on the unexpected elements kind
  b = get_literal(3);
  assertTrue(%HasFastDoubleElements(b));
  assertEquals([1, 2, 3], b);
  assertUnoptimized(get_literal);

  // Optimize again
  get_literal(3);
  %OptimizeFunctionOnNextCall(get_literal);
  b = get_literal(3);
  assertTrue(%HasFastDoubleElements(b));
  assertOptimized(get_literal);
}