768270 - IonMonkey: Inline calls to constructors

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[David Anderson [:dvander] - inactive, e-mail if emergency]

Right now we skip inlining a scripted function if the function is being called as a constructor.

Comment 1

[Sean Stangl [:sstangl]]

Attachment: Inline calls to constructors.

Straightforward. Allocation of |this| is performed caller-side; return value stitching is done by the caller to the callee's blocks.

Perf gains are minimal -- many inlining sites are denied by the Oracle due to a likely-bogus TypeBarrier on the return. Also affects non-constructors. Leaving for a separate bug.

Comment 2

[Sean Stangl [:sstangl]]

Results from x86 on a tiny benchmark that does not suffer from TI denial:

> function Foo() {
>   this.x = 5;
>   this.y = 6;
> }
> 
> function f() {
>   var a = 0;
>   for (var i = 0; i < 100000000; i++) {
>     var x = new Foo();
>     a += x.y;
>   }
>   return a;
> }
>
> f();

with patch: 2.56s
--ion-inlining=off: 3.11s
--no-ion: 2.95s

v8: 0.60s (generational)

Comment 3

[David Anderson [:dvander] - inactive, e-mail if emergency]

Comment on attachment 637725 [details] [diff] [review]
Inline calls to constructors.

Review of attachment 637725 [details] [diff] [review]:
-----------------------------------------------------------------

::: js/src/ion/MIR.h
@@ +1524,5 @@
> +// Given a MIRType_Value A and a MIRType_Object B:
> +// If the Value may be safely unboxed to an Object, return Object(A).
> +// Otherwise, return B.
> +// Used to implement return behavior for inlined constructors.
> +class MFilterObject

MReturnFromCtor?

Comment 4

[Sean Stangl [:sstangl]]

https://hg.mozilla.org/projects/ionmonkey/rev/f79d7ca811e6