GNU bug report logs - #17147
Performance regression by 3000000% for evaluating "and" form

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From: David Kastrup <dak <at> gnu.org>
To: 17147 <at> debbugs.gnu.org
Subject: bug#17147: Scalability front and back...
Date: Tue, 13 May 2014 15:03:17 +0200

[Message part 1 (text/plain, inline)]

The following code continues exploding in Guile 2.0.9 even after fixing
the VM exploding under the stock "reduce-right" and after chickening out
on syntax-case et al for "and" and using a procedural macro instead.

[zorpo.scm (text/plain, inline)]

(use-modules (srfi srfi-1))

(define (reduce-right f ridentity lst)
  "`reduce-right' is a variant of `fold-right', where the first call to
F is on two elements from LST, rather than one element and a given
initial value.  If LST is empty, RIDENTITY is returned.  If LST
has just one element then that's the return value."
  (reduce f ridentity (reverse lst)))

(define-macro (and . rest)
  (reduce-right
   (lambda (a b) `(if ,a ,b #f))
   #t
   rest))

(primitive-eval (cons 'and (make-list 10000 #f)))

[Message part 3 (text/plain, inline)]

Now I get
Backtrace:
In ice-9/psyntax.scm:
1259: 19 [#<procedure 8f2da28 (test then else)> #f (if #f (if #f # #f) #f) #f]
1259: 18 [#<procedure 8f2da00 (test then else)> #f (if #f (if #f # #f) #f) #f]
1259: 17 [#<procedure 8f2d9d8 (test then else)> #f (if #f (if #f # #f) #f) #f]
1259: 16 [#<procedure 8f2d9b0 (test then else)> #f (if #f (if #f # #f) #f) #f]
1259: 15 [#<procedure 8f2d988 (test then else)> #f (if #f (if #f # #f) #f) #f]
1259: 14 [#<procedure 8f2d960 (test then else)> #f (if #f (if #f # #f) #f) #f]
1259: 13 [#<procedure 8f2d938 (test then else)> #f (if #f (if #f # #f) #f) #f]
1259: 12 [#<procedure 8f2d910 (test then else)> #f (if #f (if #f # #f) #f) #f]
1259: 11 [#<procedure 8f2d8e8 (test then else)> #f (if #f (if #f # #f) #f) #f]
1259: 10 [#<procedure 8f2d8c0 (test then else)> #f (if #f (if #f # #f) #f) #f]
1259: 9 [#<procedure 8f2d898 (test then else)> #f (if #f (if #f # #f) #f) #f]
1259: 8 [#<procedure 8f2d870 (test then else)> #f (if #f (if #f # #f) #f) #f]
1257: 7 [#<procedure 8f2d848 (test then else)> #f (if #f (if #f # #f) #f) #f]
1186: 6 [syntax-type (if #f (if #f (if #f # ...) ...) ...) () ...]
 579: 5 [syntax-type if () ((top)) #f #f (hygiene guile-user) #t]
 293: 4 [get-global-definition-hook if (hygiene guile-user)]
In ice-9/boot-9.scm:
2697: 3 [#<procedure 8c38450 at ice-9/boot-9.scm:2696:4 (name #:optional autoload version #:key ensure)> # ...]
2512: 2 [nested-ref-module #<module () 8c25ca8> (guile-user)]
2294: 1 [module-ref-submodule #<module () 8c25ca8> guile-user]
1925: 0 [#<procedure 8c31240 at ice-9/boot-9.scm:1925:2 (module)> #]

ice-9/boot-9.scm:1925:2: In procedure #<procedure 8c31240 at ice-9/boot-9.scm:1925:2 (module)>:
ice-9/boot-9.scm:1925:2: Throw to key `vm-error' with args `(vm-run "VM: Stack overflow" ())'.


Using guile --no-auto-compile on the same file, I just get
Backtrace:
In ice-9/psyntax.scm:
1259: 19 Aborted (core dumped)


That's the stable version of GUILE included with Ubuntu 14.04.

-- 
David Kastrup

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