Re: TaggedArrays (Proposal)
Hi Jim I was wondering if you could post the use case that led you develop the TaggedArray? I looked over our Smalltalk app and I could not see an obvious pattern where mixing primitives and references in a collection is common. On a similar note I was curious how you are avoiding the integer allocation when using a 'for' like pattern to index over an array. That is a real performance hit for me so I am looking for a good solution thanks mark___ mlvm-dev mailing list mlvm-dev@openjdk.java.net http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev
Re: TaggedArrays (Proposal)
Fairly common patterns like
var p = {
fontsize: 15,
lineheight: 22,
color: 0x000,
fontfamily: "Georgia, FreeSerif, Times, serif"
};
p.color = "white";
We need flexible slots without allocating 2x memory.
For "for like" constructs we typically use static analysis to reduce to
integer. With TaggedArray slots for frames we could use integer dynamically.
Cheers,
-- Jim
On 2012-07-05, at 5:26 PM, Mark Roos wrote:
> Hi Jim
>
> I was wondering if you could post the use case that led you develop the
> TaggedArray?
> I looked over our Smalltalk app and I could not see an obvious pattern where
> mixing
> primitives and references in a collection is common.
>
> On a similar note I was curious how you are avoiding the integer allocation
> when using
> a 'for' like pattern to index over an array. That is a real performance hit
> for me so I
> am looking for a good solution
>
> thanks
> mark___
> mlvm-dev mailing list
> mlvm-dev@openjdk.java.net
> http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev
___
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Re: TaggedArrays (Proposal)
On 07/05/2012 10:42 PM, Jim Laskey wrote:
> Fairly common patterns like
>
> var p = {
> fontsize: 15,
> lineheight: 22,
> color: 0x000,
> fontfamily: "Georgia, FreeSerif, Times, serif"
> };
>
> p.color = "white";
>
> We need flexible slots without allocating 2x memory.
>
> For "for like" constructs we typically use static analysis to reduce
> to integer.
Not having such kind of analysis is almost a crime.
Jim, do you have a paper explaining the static analysis you use,
I have some trouble to keep mine linear.
> With TaggedArray slots for frames we could use integer dynamically.
yes, but performance will be awful (ok, better than using boxing but 2x
or 3x slower
than C or Java) if you don't have any kind of type propagation.
>
> Cheers,
>
> -- Jim
cheers,
Rémi
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Re: TaggedArrays (Proposal)
On 2012-07-05, at 9:26 PM, Rémi Forax wrote:
> On 07/05/2012 10:42 PM, Jim Laskey wrote:
>> Fairly common patterns like
>>
>> var p = {
>> fontsize: 15,
>> lineheight: 22,
>> color: 0x000,
>> fontfamily: "Georgia, FreeSerif, Times, serif"
>> };
>>
>> p.color = "white";
>>
>> We need flexible slots without allocating 2x memory.
>>
>> For "for like" constructs we typically use static analysis to reduce
>> to integer.
>
> Not having such kind of analysis is almost a crime.
>
> Jim, do you have a paper explaining the static analysis you use,
> I have some trouble to keep mine linear.
>
Marcus Lagergren will be doing a talk at JavaOne on type specific optimizations
that we use.
>> With TaggedArray slots for frames we could use integer dynamically.
>
> yes, but performance will be awful (ok, better than using boxing but 2x
> or 3x slower
> than C or Java) if you don't have any kind of type propagation.
We're seeing 2x using C2, but the benefit is that if you have to roll over into
another type (ex. box) you can use the same slot.
One subtlety I should point out, the plan is to have the copy method optimized
to inline small copies, so that constant length copies of 1-4 (or so) will be
native memory to memory moves. This means you can move values,
object/frame/stack to object/frame/stack without any type checking (1-1 with
C/Java.)
>
>>
>> Cheers,
>>
>> -- Jim
>
> cheers,
> Rémi
>
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Re: TaggedArrays (Proposal)
I see, it looks like you are using them to hold instance vars of objects.
I was looking for
large arrays/collections.
I have looked at this before in our app but the number of integers used
like this did not seem to
warrant much concern ( Double Vectors and byte[] are the dominant memory
users).
thanks
mark
From: Jim Laskey
To: Da Vinci Machine Project
Date: 07/05/2012 01:51 PM
Subject:Re: TaggedArrays (Proposal)
Sent by:mlvm-dev-boun...@openjdk.java.net
Fairly common patterns like
var p = {
fontsize: 15,
lineheight: 22,
color: 0x000,
fontfamily: "Georgia, FreeSerif, Times, serif"
};
p.color = "white";
We need flexible slots without allocating 2x memory.
For "for like" constructs we typically use static analysis to reduce to
integer. With TaggedArray slots for frames we could use integer
dynamically.
Cheers,
-- Jim
On 2012-07-05, at 5:26 PM, Mark Roos wrote:
Hi Ji! m
I was wondering if you could post the use case that led you develop the
TaggedArray?
I looked over our Smalltalk app and I could not see an obvious pattern
where mixing
primitives and references in a collection is common.
On a similar note I was curious how you are avoiding the integer
allocation when using
a 'for' like pattern to index over an array. That is a real performance
hit for me so I
am looking for a good solution
thanks
mark___
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mlvm-dev@openjdk.java.net
http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev
___
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