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let toBeIncremented = 0;
function megamorphicGetIncremented(thisIsMegamorphic, thisIsAlwaysTrue) {
// We need this to always evaluate as foo, and have an else clause which
// would bail if we ever hit it.
let key = thisIsAlwaysTrue ? "foo" : thisIsMegamorphic.bob;
// The first megamorphic load:
if (!thisIsMegamorphic[key]) {
// The store which invalidates it
thisIsMegamorphic[key] = ++toBeIncremented;
}
// The megamorphic load which was bugged
return thisIsMegamorphic[key];
}
// We just need enough shapes to go megamorphic. Put in a bunch though
// just to be sure
let objShapes = [
{a: 1},
// We need the shapes to occasionally have "foo" defined, but be false,
// otherwise stub folding will mean we don't go megamorphic because
// we'll just attach "Missing" which in our case just differs by a
// single shape guard.
{b: 1, baz: 2, foo: false},
{c: 1},
{d: 1, baz: 2, foo: false},
{e: 1},
{f: 1, baz: 2, foo: false},
{g: 1},
{h: 1, baz: 2, foo: false},
{i: 1},
{j: 1, baz: 2, foo: false},
{k: 1},
{l: 1, baz: 2, foo: false},
{m: 1},
{n: 1, baz: 2, foo: false},
{o: 1},
{p: 1, baz: 2, foo: false},
{q: 1},
{r: 1, baz: 2, foo: false},
{s: 1},
{t: 1, baz: 2, foo: false},
];
let objs = [];
for (let i = 0; i < 100; i++) {
let obj = Object.assign({}, objShapes[i % objShapes.length]);
objs.push(obj);
}
for (let i = 1; i < 100; i++) {
let id = megamorphicGetIncremented(objs[i], true);
assertEq(id, i);
}