[racket-dev] [plt] Push #27767: master branch updated

On 11/14/2013 03:22 PM, stamourv at racket-lang.org wrote:
> stamourv has updated `master' from 44f810aa72 to a87dcc252e.
>    http://git.racket-lang.org/plt/44f810aa72..a87dcc252e
>
> =====[ 4 Commits ]======================================================
> Directory summary:
>    20.3% pkgs/contract-profile/
>    39.5% pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/optimizer/
>    20.9% pkgs/typed-racket-pkgs/typed-racket-test/tests/typed-racket/optimizer/missed-optimizations/
>    17.2% pkgs/typed-racket-pkgs/typed-racket-test/tests/typed-racket/optimizer/tests/
>
> ~~~~~~~~~~
>
> 0dccecc Vincent St-Amour <stamourv at racket-lang.org> 2013-11-12 17:40
> :
> | Clarify impedance mismatch between profiler and blame info.
> :
>    M pkgs/contract-profile/boundary-view.rkt | 15 ++++++++-------
>
> ~~~~~~~~~~
>
> 04eeeb1 Vincent St-Amour <stamourv at racket-lang.org> 2013-11-13 18:24
> :
> | Log hidden prng parameter dereferences.
> :
>    M .../typed-racket-lib/typed-racket/optimizer/hidden-costs.rkt | 8 ++++++++
>
> ~~~~~~~~~~
>
> 7616e26 Vincent St-Amour <stamourv at racket-lang.org> 2013-11-14 11:04
> :
> | Add types and optimizations for flrandom and unsafe-flrandom.
> :
>    A pkgs/typed-racket-pkgs/typed-racket-test/tests/typed-racket/optimizer/tests/flrandom.rkt
>    M .../typed-racket/base-env/base-env-numeric.rkt     |  3 +++
>    M .../typed-racket/optimizer/float.rkt               | 19 ++++++++++++++++++-
>    M .../typed-racket/optimizer/hidden-costs.rkt        |  4 ++++
>
> ~~~~~~~~~~
>
> a87dcc2 Vincent St-Amour <stamourv at racket-lang.org> 2013-11-14 14:11
> :
> | Log non-optimized fixnum-specific ops as hidden costs.
> :
>    M .../optimizer/missed-optimizations/fixnum.rkt       |  6 +++---
>    M .../optimizer/tests/fixnum-bounded-expr.rkt         |  8 ++++----
>    M .../optimizer/tests/invalid-fxquotient.rkt          |  2 +-
>    A pkgs/typed-racket-pkgs/typed-racket-test/tests/typed-racket/optimizer/missed-optimizations/fixnum-no-bound.rkt
>    M .../typed-racket/optimizer/fixnum.rkt               | 18 ++++++++++++++++--
>
> =====[ Overall Diff ]===================================================
>

For the following program, on my computer, the new "random -> 
unsafe-flrandom" optimization slows down the first loop and speeds up 
the second:

#lang typed/racket

(require math/flonum
          racket/unsafe/ops)

(define g (current-pseudo-random-generator))
(define bx (make-flvector 1))

(for: ([_  (in-range 5)])
   (time (for: ([_  (in-range 5000000)])
           (unsafe-flvector-set! bx 0 (random)))))
(newline)

(for: ([_  (in-range 5)])
   (time (for: ([_  (in-range 5000000)])
           (unsafe-flvector-set! bx 0 (random g)))))


IOW, it appears the optimization only helps when passing in a 
pseudo-random generator. I suspected this might be the case when I ran a 
bunch of tests of the math library's sampling algorithms and some of 
them were a hair slower after updating my Racket repo.

The only reason I can think of that this would be the case is if the 
built-in's parameter retrieval is faster. Anyhow, changing (random) to 
(unsafe-flrandom (current-pseudo-random-generator)) looks like a 
pessimization for now.

(I'm going to speed up the math library's samplers by caching the 
parameter value and using the new `flrandom', but of course that's a 
separate issue.)

Neil ⊥