Gambit-list Avril 2007

gambit-list@iro.umontreal.ca

23 participants
47 discussions

What's new?
by Bradley Lucier 05 Avr '07

05 Avr '07

Marc: Do you want to say a few words about what's new in 4.0b22 since 4.0b20? Bug fixes, etc.? I searched the documentation and other files, but there's been a lot of source changes with not very many notes. Brad

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debugger problem
by |/|/ Bendick 04 Avr '07

04 Avr '07

I'm having a problem with the gambit debugger. If I understand correctly ",l" should differ from ",s" in that ",l" leaps over the expression in question without stepping through the call while ",s" will step through. If that is correct the problem is ",l" is performing the same function as ",s" -- it steps into the code. I'm having this problem with b21, b20, b19.. Is anyone else experiencing this? Anyone have a fix? Unrelated-- I've noticed that when using gambit in emacs it always thinks by screen width is 80 > (output-port-width (repl-output-port)) 80 even when the terminal is 164 characters wide. I started emacs and gambit with the terminal already at this width. The width is correctly reported if I just start gsi from command line. I've noticed these problems on mac os x and netbsd so I don't think it's something funky on my end. Can anyone help? Thanks in advance! -- |/|/ Bendick

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non-tail recursion segfaults
by Phil Dawes 03 Avr '07

03 Avr '07

Hi Gambit list, I've started getting segmentation faults whenever I compile srfi-1.scm[1] and use it within my program and was wondering if it was to do with non-tail recursion. I did a quick experiment and found that on my machine the following code compiled with gsc segfaults when i is just 20000 (it works fine interpreted): -------------- (define (loop i) (if (zero? i) '() (cons i (loop (- i 1))))) (loop 20000) -------------- This seems quite limiting - is there flag I can tweak to improve this? Many thanks, Phil [1] https://webmail.iro.umontreal.ca/pipermail/gambit-list/2005-March/000168.ht…

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Floating-point codes for testing register allocation
by Bradley Lucier 03 Avr '07

03 Avr '07

Marc: I've included below two files that I hope will eventually replace the fft bignum multiplication routines in _num.scm. (The advantage of the new approach is that it is provably correct; I'm waiting to see if there are any disadvantages.) The main loops in direct-fft-recursive and inverse-fft-recursive are scheduled to take 122 and 96 cycles, respectively, on my G5 using CC='gcc -mcpu=970 -m64' with the official Apple gcc 4.0.1; most of the time is taken in constantly reloading W and a from the stack. (You can find this information by passing -dR to gcc. BTW, why does b21 erase the .c file after compiling something with -dynamic? It's almost as if you're embarrassed by the C code that gsc generates ;-) If the number of registers are increased so that W and a are kept in registers, then these two loops are each scheduled in about 31 cycles, the same as a hand rewrite of the code in C. Please see whether some type of SSA form for GVM variables used in a basic block improves performance the same way that generating SSA- type code for F64 variables in each basic block helped the floating- point code. Some trivial timing comparisons with the existing code are given below. I hope that when I'm done the new code will be faster than the old. (For example, the new code is more "cache-oblivious" than the old.) Brad > [descartes:~/programs/gambc40b17/fftmul] lucier% gsc -:m100000 > Gambit Version 4.0 beta 21 > > > (load "fftmul-fast") > "/Users/lucier/programs/gambc40b17/fftmul/fftmul-fast.o2" > > (define a (expt 3 10000000)) > > (define b (expt 3 10000000)) > > (define c (time (* a a))) > (time (* a a)) > 2193 ms real time > 2090 ms cpu time (1948 user, 142 system) > 1 collection accounting for 22 ms real time (3 user, 19 system) > 110229552 bytes allocated > no minor faults > no major faults > > (define d (time (fft-mul a a))) > (time (fft-mul a a)) > 2621 ms real time > 2431 ms cpu time (2203 user, 228 system) > 1 collection accounting for 44 ms real time (4 user, 40 system) > 112555696 bytes allocated > no minor faults > no major faults > > (define e (time (* a b))) > (time (* a b)) > 3659 ms real time > 3002 ms cpu time (2777 user, 225 system) > 1 collection accounting for 77 ms real time (3 user, 74 system) > 171743360 bytes allocated > no minor faults > no major faults > > (define f (time (fft-mul a b))) > (time (fft-mul a b)) > 4007 ms real time > 3585 ms cpu time (3219 user, 366 system) > 1 collection accounting for 64 ms real time (3 user, 61 system) > 183596720 bytes allocated > no minor faults > no major faults > > (= c d) > #t > > (= e f) > #t

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Speeding up rational arithmetic
by Bradley Lucier 02 Avr '07

02 Avr '07

Marc: I thought that I might speed up rational arithmetic a bit in the common case where the numerators and denominators are small integers, so I tried some new declarations: (define-prim (##ratnum.* x y) (##declare (run-time-bindings) (mostly-fixnum)) (let ((p (macro-ratnum-numerator x)) (q (macro-ratnum-denominator x)) (r (macro-ratnum-numerator y)) (s (macro-ratnum-denominator y))) (if (##eq? x y) (macro-ratnum-make (* p p) (* q q)) ; already in lowest form (let* ((gcd-ps (gcd p s)) (gcd-rq (gcd r q)) (num (* (quotient p gcd-ps) (quotient r gcd-rq))) (den (* (quotient q gcd-rq) (quotient s gcd-ps)))) (if (##eq? den 1) num (macro-ratnum-make num den)))))) but this isn't quite right, since, e.g., for the form (* p p), if p is not a fixnum, then gsc generates calls to (* p p) instead of (##* p p) even though (declare (standard-bindings) is in effect. So a user could screw up rational arithmetic simply by redefining * (which is allowed, after all). Perhaps the code generator should be changed to call (##* p p) directly in this case. The full expansion is below. Brad (define ##ratnum.* (lambda (x y) (let ((s ('#<procedure #7 ##vector-ref> y 1)) (r ('#<procedure #7 ##vector-ref> y 0)) (q ('#<procedure #7 ##vector-ref> x 1)) (p ('#<procedure #7 ##vector-ref> x 0))) (if ('#<procedure #27 ##eq?> x y) ('#<procedure #75 ##subtype-set!> ('#<procedure #76 ##vector> (if (and ('#<procedure #14 ##fixnum?> p) ('#<procedure #14 ##fixnum?> p)) (if ('#<procedure #298 ##eqv?> p 0) 0 (let ((temp.236 (if ('#<procedure #298 ##eqv?> p -1) ('#<procedure #207 ##fx-?> p) ('#<procedure #208 ##fx*?> p p)))) (if temp.236 temp.236 (* p p)))) (* p p)) (if (and ('#<procedure #14 ##fixnum?> q) ('#<procedure #14 ##fixnum?> q)) (if ('#<procedure #298 ##eqv?> q 0) 0 (let ((temp.239 (if ('#<procedure #298 ##eqv?> q -1) ('#<procedure #207 ##fx-?> q) ('#<procedure #208 ##fx*?> q q)))) (if temp.239 temp.239 (* q q)))) (* q q))) 2) (let ((gcd-ps ('#<procedure #94 gcd> p s))) (let ((gcd-rq ('#<procedure #94 gcd> r q))) (let ((num (let ((temp.245 (if (and ('#<procedure #14 ##fixnum? > gcd-rq) (and ('#<procedure #14 ##fixnum?> r) ('#<procedure #21 ##not> ('#<procedure #298 ##eqv?> gcd-rq 0)))) (if ('#<procedure #298 ##eqv?> gcd-rq -1) (or ('#<procedure #207 ##fx-? > r) (quotient r gcd-rq)) ('#<procedure #216 ##fxquotient> r gcd-rq)) (quotient r gcd-rq))) (temp.244 (if (and ('#<procedure #14 ##fixnum? > gcd-ps) (and ('#<procedure #14 ##fixnum?> p) ('#<procedure #21 ##not> ('#<procedure #298 ##eqv?> gcd-ps 0)))) (if ('#<procedure #298 ##eqv?> gcd-ps -1) (or ('#<procedure #207 ##fx-? > p) (quotient p gcd-ps)) ('#<procedure #216 ##fxquotient> p gcd-ps)) (quotient p gcd-ps)))) (if (and ('#<procedure #14 ##fixnum?> temp.245) ('#<procedure #14 ##fixnum?> temp.244)) (if ('#<procedure #298 ##eqv?> temp. 245 0) 0 (let ((temp.246 (if ('#<procedure #298 ##eqv?> temp.245 -1) ('#<procedure #207 ##fx-?> temp.244) ('#<procedure #208 ##fx*?> temp.244 temp.245)))) (if temp.246 temp.246 (* temp.244 temp.245)))) (* temp.244 temp.245))))) (let ((den (let ((temp.252 (if (and ('#<procedure #14 ##fixnum?> gcd-ps) (and ('#<procedure #14 ##fixnum?> s) ('#<procedure #21 ##not> ('#<procedure #298 ##eqv?> gcd-ps 0)))) (if ('#<procedure #298 ##eqv?> gcd-ps -1) (or ('#<procedure #207 ##fx-?> s) (quotient s gcd-ps)) ('#<procedure #216 ##fxquotient> s gcd-ps)) (quotient s gcd-ps))) (temp.251 (if (and ('#<procedure #14 ##fixnum?> gcd-rq) (and ('#<procedure #14 ##fixnum?> q) ('#<procedure #21 ##not> ('#<procedure #298 ##eqv?> gcd-rq 0)))) (if ('#<procedure #298 ##eqv?> gcd-rq -1) (or ('#<procedure #207 ##fx-?> q) (quotient q gcd-rq)) ('#<procedure #216 ##fxquotient> q gcd-rq)) (quotient q gcd-rq)))) (if (and ('#<procedure #14 ##fixnum?> temp.252) ('#<procedure #14 ##fixnum?> temp.251)) (if ('#<procedure #298 ##eqv?> temp. 252 0) 0 (let ((temp.253 (if ('#<procedure #298 ##eqv?> temp.252 -1) ('#<procedure #207 ##fx-?> temp.251) ('#<procedure #208 ##fx*?> temp.251 temp.252)))) (if temp.253 temp.253 (* temp.251 temp.252)))) (* temp.251 temp.252))))) (if ('#<procedure #27 ##eq?> den 1) num ('#<procedure #75 ##subtype-set!> ('#<procedure #76 ##vector> num den) 2))))))))))

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Gambit-C submitted to MacPorts
by Arto Bendiken 02 Avr '07

02 Avr '07

I've submitted Gambit as a proposed new port [1] for inclusion in the MacPorts packaging system [2]. Once the port is accepted, installing Gambit on a Mac OS X system will be as simple as: # sudo port install gambit-c I had to do quite a bit of patching [3] of the installation paths in the makefiles to comply with the MacPorts directory structure. Perhaps some of the changes, like prefixing installation paths with $(DESTDIR), could be integrated into future Gambit versions to ensure easier interoperability with various packaging systems including MacPorts. Cheers, Arto [1] http://trac.macports.org/projects/macports/ticket/11688 [2] http://en.wikipedia.org/wiki/MacPorts [3] http://trac.macports.org/projects/macports/attachment/ticket/11688/Portfile -- Arto Bendiken | http://bendiken.net/

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Fwd: gaps in the mesh
by Oana Petrache 02 Avr '07

02 Avr '07

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Gambit-list Avril 2007