objectfuse-global-state.js

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// |jit-test| --setpref=objectfuse_for_global=true

function markConstant(obj, key) {

  assertEq(getObjectFuseState(obj).properties[key], "Untracked");

  // This relies on the fact that storing to an Untracked property marks it

  // Constant. Use getOwnPropertyDescriptor to prevent interacting with JIT

  // optimizations.

  obj[key] = Object.getOwnPropertyDescriptor(obj, key).value;

function testGlobal() {

  var g = newGlobal({sameCompartmentAs: this, useWindowProxy: false});

  assertEq(getObjectFuseState(g).generation, 0);

  // Ensure global variables are marked untracked or constant.

  g.evaluate("var foo = 1; var bar; bar = function() {}; function baz() {};");

  var state = getObjectFuseState(g);

  assertEq(state.properties.foo, "Constant");

  assertEq(state.properties.bar, "Constant");

  assertEq(state.properties.baz, "Untracked");

  // Shadowing a non-constant global on the lexical environment doesn't change

  // the generation.

  g.evaluate("let Object = {};");

  assertEq(getObjectFuseState(g).generation, 0);

  // Shadowing a constant property does change the generation.

  markConstant(g, "Function");

  g.evaluate("let Function = {};");

  assertEq(getObjectFuseState(g).generation, 1);

  // Shadowing a no-longer-constant property must also change the generation because

  // IC stubs may still have guards for this property.

  g.Math = 1;

  g.Math = 2;

  g.evaluate("let Math = {};");

  assertEq(getObjectFuseState(g).generation, 2);

testGlobal();

testGlobal();