RE: How do we best make sure {Int,Word,Float,Double} to {Int,Word,Float,Double} conversions stay efficient
Best thing to do is to produce a concrete example, showing the code you think
is sub-optimal
Simon
From: glasgow-haskell-users-boun...@haskell.org
[mailto:glasgow-haskell-users-boun...@haskell.org] On Behalf Of Sean Leather
Sent: 14 December 2012 22:13
To: GHC Users List; Ian Lynagh
Subject: Re: How do we best make sure {Int,Word,Float,Double} to
{Int,Word,Float,Double} conversions stay efficient
On Fri, Dec 14, 2012 at 10:47 PM, Ian Lynagh wrote:
On Fri, Dec 14, 2012 at 04:34:29PM -0500, Carter Schonwald wrote:
> A related question I have is that I've some code that will map the
> singleton Nats to Ints, and last time I looked into this/ had a chat on the
> ghc-users list, it sounded like sometimes having Integer values constructed
> in between are unavoidable. Is that still the case with post 7.6.1 ghc?
> (And or, how might I be able to help?)
I don't know what a singleton Nat is, but if you mean Word then that's
what Johan's been working on.
I'm guessing Carter means Sing Nat:
http://www.haskell.org/ghc/docs/latest/html/libraries/base-4.6.0.0/src/GHC-TypeLits.html
Regards,
Sean
___
Glasgow-haskell-users mailing list
Glasgow-haskell-users@haskell.org
http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: How do we best make sure {Int,Word,Float,Double} to {Int,Word,Float,Double} conversions stay efficient
The sure-fire way is to make a loop that doesn't allocate if the rules fire;
after all that's the ultimate goal. Then you can put it in
tests/perf/should_run.
doing -ddump-simpl and greping for stuff that should/should-not be there is
another alternative we use in places.
Simon
| -Original Message-
| From: glasgow-haskell-users-boun...@haskell.org [mailto:glasgow-haskell-
| users-boun...@haskell.org] On Behalf Of Johan Tibell
| Sent: 14 December 2012 20:54
| To: glasgow-haskell-users
| Subject: How do we best make sure {Int,Word,Float,Double} to
| {Int,Word,Float,Double} conversions stay efficient
|
| Hi,
|
| I've been tracking down a few (unrelated) performance bugs related to
| conversions between primitive types. What these issues had in common is
| that some rule failed to fire and the conversion went via Integer,
| killing performance. How do we best write a test that make sure that
| fromIntegral conversions between these types don't regress? Is it
| possible to test the output of the simplifier or do we have to do
| something less direct, like writing a loop that does such conversions
| and make sure that the allocation stay low?
|
| -- Johan
|
| ___
| Glasgow-haskell-users mailing list
| Glasgow-haskell-users@haskell.org
| http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
___
Glasgow-haskell-users mailing list
Glasgow-haskell-users@haskell.org
http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: How do we best make sure {Int,Word,Float,Double} to {Int,Word,Float,Double} conversions stay efficient
I believe the testsuite now has support for inspecting assembly output. Not sure if that would be best for your use case, but something to consider. On 14 December 2012 12:53, Johan Tibell wrote: > Hi, > > I've been tracking down a few (unrelated) performance bugs related to > conversions between primitive types. What these issues had in common > is that some rule failed to fire and the conversion went via Integer, > killing performance. How do we best write a test that make sure that > fromIntegral conversions between these types don't regress? Is it > possible to test the output of the simplifier or do we have to do > something less direct, like writing a loop that does such conversions > and make sure that the allocation stay low? > > -- Johan > > ___ > Glasgow-haskell-users mailing list > Glasgow-haskell-users@haskell.org > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: How do we best make sure {Int,Word,Float,Double} to {Int,Word,Float,Double} conversions stay efficient
Yes, thanks Sean for helping clarify! yes, The TypeLits Nat I had a discussion on the list with Iavor and others a few months back http://www.haskell.org/pipermail/glasgow-haskell-users/2012-August/022789.html and there were some examples and dialogue beyond that with Iavor and SPJ, but it was off list. point being: for Word or Int sized instances of Nat singleton, theres a number of interesting ways having that information used to statically specialize a numerical computation with some constants is handy, and last time I asked it sounded like the story for this wasn't fully worked out. I hope I'm explaining clearly, if not I'll be happy to try to elaborate further -Carter On Fri, Dec 14, 2012 at 5:12 PM, Sean Leather wrote: > On Fri, Dec 14, 2012 at 10:47 PM, Ian Lynagh wrote: > > On Fri, Dec 14, 2012 at 04:34:29PM -0500, Carter Schonwald wrote: >> > A related question I have is that I've some code that will map the >> > singleton Nats to Ints, and last time I looked into this/ had a chat on >> the >> > ghc-users list, it sounded like sometimes having Integer values >> constructed >> > in between are unavoidable. Is that still the case with post 7.6.1 ghc? >> > (And or, how might I be able to help?) >> >> I don't know what a singleton Nat is, but if you mean Word then that's >> what Johan's been working on. >> > > I'm guessing Carter means Sing Nat: > > http://www.haskell.org/ghc/docs/latest/html/libraries/base-4.6.0.0/src/GHC-TypeLits.html > > Regards, > Sean > > ___ > Glasgow-haskell-users mailing list > Glasgow-haskell-users@haskell.org > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users > > ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: How do we best make sure {Int,Word,Float,Double} to {Int,Word,Float,Double} conversions stay efficient
On Fri, Dec 14, 2012 at 10:47 PM, Ian Lynagh wrote: > On Fri, Dec 14, 2012 at 04:34:29PM -0500, Carter Schonwald wrote: > > A related question I have is that I've some code that will map the > > singleton Nats to Ints, and last time I looked into this/ had a chat on > the > > ghc-users list, it sounded like sometimes having Integer values > constructed > > in between are unavoidable. Is that still the case with post 7.6.1 ghc? > > (And or, how might I be able to help?) > > I don't know what a singleton Nat is, but if you mean Word then that's > what Johan's been working on. > I'm guessing Carter means Sing Nat: http://www.haskell.org/ghc/docs/latest/html/libraries/base-4.6.0.0/src/GHC-TypeLits.html Regards, Sean ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: How do we best make sure {Int,Word,Float,Double} to {Int,Word,Float,Double} conversions stay efficient
Hi Carter, On Fri, Dec 14, 2012 at 04:34:29PM -0500, Carter Schonwald wrote: > A related question I have is that I've some code that will map the > singleton Nats to Ints, and last time I looked into this/ had a chat on the > ghc-users list, it sounded like sometimes having Integer values constructed > in between are unavoidable. Is that still the case with post 7.6.1 ghc? > (And or, how might I be able to help?) I don't know what a singleton Nat is, but if you mean Word then that's what Johan's been working on. Thanks Ian ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: How do we best make sure {Int,Word,Float,Double} to {Int,Word,Float,Double} conversions stay efficient
A related question I have is that I've some code that will map the singleton Nats to Ints, and last time I looked into this/ had a chat on the ghc-users list, it sounded like sometimes having Integer values constructed in between are unavoidable. Is that still the case with post 7.6.1 ghc? (And or, how might I be able to help?) On Friday, December 14, 2012, Ian Lynagh wrote: > On Fri, Dec 14, 2012 at 12:53:36PM -0800, Johan Tibell wrote: > > > > I've been tracking down a few (unrelated) performance bugs related to > > conversions between primitive types. What these issues had in common > > is that some rule failed to fire and the conversion went via Integer, > > killing performance. How do we best write a test that make sure that > > fromIntegral conversions between these types don't regress? Is it > > possible to test the output of the simplifier or do we have to do > > something less direct, like writing a loop that does such conversions > > and make sure that the allocation stay low? > > We have some tests looking at the -ddumjp-simpl output, e.g. > integerConstantFolding. I'm not sure if we have one for type conversions > OTTOMH. > > > Thanks > Ian > > > ___ > Glasgow-haskell-users mailing list > Glasgow-haskell-users@haskell.org > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users > ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: How do we best make sure {Int,Word,Float,Double} to {Int,Word,Float,Double} conversions stay efficient
On Fri, Dec 14, 2012 at 12:53:36PM -0800, Johan Tibell wrote: > > I've been tracking down a few (unrelated) performance bugs related to > conversions between primitive types. What these issues had in common > is that some rule failed to fire and the conversion went via Integer, > killing performance. How do we best write a test that make sure that > fromIntegral conversions between these types don't regress? Is it > possible to test the output of the simplifier or do we have to do > something less direct, like writing a loop that does such conversions > and make sure that the allocation stay low? We have some tests looking at the -ddumjp-simpl output, e.g. integerConstantFolding. I'm not sure if we have one for type conversions OTTOMH. Thanks Ian ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
