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: Performance regression by 3000000% for evaluating "and" form
Date: Mon, 31 Mar 2014 11:58:00 +0200

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

The following program goes from 2.3ms execution time to 80s execution
time when going from Guile-1.8 to current master.

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

(use-modules (srfi srfi-19))
(define start-time (current-time))
(primitive-eval (cons 'and (make-list 10000 #f)))
(display (time-difference (current-time) start-time))

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

With Guile-2.0.9 (Ubuntu package), it crashes with
Backtrace:
In ice-9/psyntax.scm:
2683: 19 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 18 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 17 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 16 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 15 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 14 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 13 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 12 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 11 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 10 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 9 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 8 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 7 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 6 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 5 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 4 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 3 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 2 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 1 [match-each-any (#f #f #f ...) ((#f top) shift) ...]
2683: 0 [match-each-any (#f #f #f ...) ((#f top) shift) ...]

ice-9/psyntax.scm:2683:37: In procedure match-each-any:
ice-9/psyntax.scm:2683:37: Throw to key `vm-error' with args `(vm-run "VM: Stack overflow" ())'.

which might give a clue as to where Guile-v2 is spending all its time.

-- 
David Kastrup

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