549513 - (JaegerPIC) [meta] JM: PIC

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[David Mandelin [:dmandelin]]

This is a meta bug for tracking work on PICs for JaegerMonkey. 

We'll start out with some analysis; for all we know the property cache is already the ideal implementation, but we need to check into it.

Comment 1

[Brendan Eich [:brendan]]

The property cache was good for Firefox 3 / JS1.8, but it's far from ideal. See bug 497789, finally about to be (mega-)patched. You should start with that patch applied, don't waste time without it.

/be

Comment 2

[David Mandelin [:dmandelin]]

WebKit and V8 have pretty much the same PIC design, which pretty much follows the Self paper extended to property access (the paper mainly treated method calls), so I think it makes sense to go ahead with that.

ETA is May 1 for all basic patches submitted for review.

This is a very rough estimate, really just a guess. I should be able to do better once I've gotten at least one major chunk done. Initial plan is:

1. PIC for |o.x| 
   Once this is done the rest should be easier, basically variations on this
   theme.

2. PIC for |o.x = e|

3. PIC for |o.x()| 
   This one may be a bit harder; both V8 and WebKit have specialized
   optimizations for calls. I haven't studied them yet but my guess is they 
   are similar to the ones we have for the property cache.

4. PIC for |o[e]|

5. PIC for |o[e] = e'|

Comment 3

[David Mandelin [:dmandelin]]

Update on the estimate. It's been just about 3 weeks to "basically finish" PICs for getprop. There are 5 bugs to completely finish that. I'd estimate about 0.5 weeks for those. Going with the original estimate, that leaves 3 weeks to do callprop and setprop, meaning those could be done together in about the same time it took to do just getprop. For now, I'm going to say that seems right--the knowledge and utility code I've built up should make the rest go faster. So no revision to the estimate for now.

Comment 4

[David Mandelin [:dmandelin]]

PIC is now working on Win x64. Perf wins are similar to what they are on x86. There are probably still bugs in the PIC for Linux x64. I'm installing a VM to take care of that.