1422726 - Optimize NativeObject::addEnumerableDataProperty

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect, P3)

Description

[Jan de Mooij [:jandem]]

Attachment: Patch

addEnumerableDataProperty is one of the hottest functions on Speedometer and adding new properties to objects is still slower than it should be.

The attached patch adds a fast path to addEnumerableDataProperty for non-dictionary objects that have a single kid shape that matches the new property. This fast path hits most of the time on both Octane and Speedometer.

For the micro-benchmark below I get the following, best of 5 runs:

before: 945 ms
after:  811 ms

It also improves six-speed's object-assign-es6 test from 237 ms to 208 ms.

There's more to optimize here but this is a good start.

function g(a) {
    var o = {};
    for (var i = 0; i < a.length; i++) {
        o[a[i]] = i;
    }
    return o;
}
function f() {
    var arr = ["a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9"];
    var t = new Date;
    for (var i = 0; i < 1000000; i++)
        res = g(arr);
    print(new Date - t);
}
f();

Comment 1

[Jan de Mooij [:jandem]]

Oops, that micro-benchmark is wrong, the numbers are for this slightly simpler one:

function f() {
    var arr = ["a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9"];
    var t = new Date;
    for (var i = 0; i < 1000000; i++) {
        res = {};
        for (var j = 0; j < arr.length; j++) {
            res[arr[j]] = i;
        }
    }
    print(new Date - t);
}
f();

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/10aa5c0593fa
Optimize addEnumerableDataProperty by adding a fast path for the most common case. r=bhackett

Comment 3

[Bogdan Tara[:bogdan_tara | bogdant]]

https://hg.mozilla.org/mozilla-central/rev/10aa5c0593fa