v8/test/mjsunit/allocation-folding.js

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// Flags: --allow-natives-syntax --nouse-osr --expose-gc

// Test loop barrier when folding allocations.

function f() {
  var elem1 = [1,2,3];
  for (var i=0; i < 100000; i++) {
    var bar = [1];
  }
  var elem2 = [1,2,3];
  return elem2;
}

f(); f(); f();
%OptimizeFunctionOnNextCall(f);
var result = f();

gc();

assertEquals(result[2], 3);

// Test allocation folding of doubles.

function doubles() {
  var elem1 = [1.1, 1.2];
  var elem2 = [2.1, 2.2];
  return elem2;
}

doubles(); doubles(); doubles();
%OptimizeFunctionOnNextCall(doubles);
result = doubles();

gc();

assertEquals(result[1], 2.2);

// Test allocation folding of doubles into non-doubles.

function doubles_int() {
  var elem1 = [2, 3];
  var elem2 = [2.1, 3.1];
  return elem2;
}

doubles_int(); doubles_int(); doubles_int();
%OptimizeFunctionOnNextCall(doubles_int);
result = doubles_int();

gc();

assertEquals(result[1], 3.1);

// Test allocation folding over a branch.

function branch_int(left) {
  var elem1 = [1, 2];
  var elem2;
  if (left) {
    elem2 = [3, 4];
  } else {
    elem2 = [5, 6];
  }
  return elem2;
}

branch_int(1); branch_int(1); branch_int(1);
%OptimizeFunctionOnNextCall(branch_int);
result = branch_int(1);
var result2 = branch_int(0);

gc();

assertEquals(result[1], 4);
assertEquals(result2[1], 6);