696409 - Give Call slot 2 a more useful tracing detail

Status: RESOLVED INCOMPLETE

(Core :: JavaScript Engine, defect)

Description

[Andrew McCreight [:mccr8]]

The tracing details for a Call don't seem to be set to a useful value:

0x120cbc848 0x117a3d000 Call 0
> 0x120cbc230 parent
> 0x118306c00 shape
> 0x12108dc90 **UNKNOWN SLOT 0**
> 0x118308280 aProp

It looks like this is a Function?  I guess the slot name could be function or something?

Comment 1

[Andrew McCreight [:mccr8]]

This is now **UNKNOWN SLOT 2**.

0x12052bd00 [gc] JS Object (Call)
> 0x1205d2580 **UNKNOWN SLOT 2**
> 0x12059dc00 self
> 0x1205d80a0 boundargs

Do you know what slot 2 is in a call, Luke? It points to some kind of arguments object like this:

0x1205d2580 [gc] JS Object (Arguments)
> 0x12059dc00 arguments[1]

Comment 2

[Luke Wagner [:luke]]

That would be the "arguments" slot of the call object :)  (See CallObject::ARGUMENTS_SLOT)

Comment 3

[Andrew McCreight [:mccr8]]

Ah, cool.  I guess boundargs are a different kind of argument then.

Comment 4

[Luke Wagner [:luke]]

I'm not positive, but I think those would be hanging off "bound function objects", i.e., the objects produced by Function.prototype.bind.

Comment 5

[Andrew McCreight [:mccr8]]

I looked into this recently, and I couldn't figure out exactly what this was referring to, so I'm just going to close it.