892931 - IonMonkey: CallKnown: Don't emit slow path if callee can't be Ion-compiled but can be Baseline-compiled

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Jan de Mooij [:jandem]]

Attachment: Patch

CallKnown emits a slow path if the callee can't be Ion-compiled. However, nowadays we can also call into Baseline scripts using the same code so going through the VM in this case is no longer necessary in most cases (since Baseline compiles almost everything).

Here's a simple micro-benchmark:

function g() {
    try { } catch(e) {}
    return 3;
}
function f() {
    for (var i=0; i<10000000; i++)
	g();
}
var t = new Date;
f();
print(new Date - t);

Before: 1747 ms
After :   98 ms

(Noticed this while looking at some fuzz bug.)

Comment 1

[Hannes Verschore [:h4writer]]

Comment on attachment 774576 [details] [diff] [review]
Patch

Review of attachment 774576 [details] [diff] [review]:
-----------------------------------------------------------------

Nice catch !!

Comment 2

[Jan de Mooij [:jandem]]

Thanks for another quick review!

https://hg.mozilla.org/integration/mozilla-inbound/rev/d1f17915555b

Comment 3

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/d1f17915555b