[Openmcl-devel] Erroneous results if function is untraced

Liam Healy lnp at healy.washington.dc.us
Wed Dec 31 02:05:48 UTC 2008


 (lisp-implementation-version)
"Version 1.2-r10552  (LinuxX8664)"

In testing my system GSLL, an interface to the GNU Scientific Library
(GSL), I have found a few failures under CCL.  These tests will run
correctly if the function is traced, or if the values are defined with
a defparameter.  In this example, #(0 0 0 0) is the wrong answer, #(3
2 1 0) is the correct answer:

Welcome to Clozure Common Lisp Version 1.2-r10552  (LinuxX8664)!
? (clc:clc-require :gsll-tests)
T
? (in-package :gsl)
#<Package "GSLL">

;; Call inside let, fails
? (let ((perm (make-permutation 4 T))) (permutation-reverse perm))
#<PERMUTATION #(0 0 0 0)>

;; Trace the function and repeat, suceeds:
? (trace permutation-reverse)
NIL
? (let ((perm (make-permutation 4 T))) (permutation-reverse perm))
0> Calling (PERMUTATION-REVERSE #<PERMUTATION #(0 1 2 3)>)
<0 PERMUTATION-REVERSE returned #<PERMUTATION #(3 2 1 0)>
#<PERMUTATION #(3 2 1 0)>

;; No tracing, use defparameter, succeeds:
? (defparameter *perm* (make-permutation 4 t))
*PERM*
? *perm*
#<PERMUTATION #(0 1 2 3)>
? (permutation-reverse *perm*)
#<PERMUTATION #(3 2 1 0)>

;; Direct call fails:
? (permutation-reverse (make-permutation 4 t))
#<PERMUTATION #(0 0 0 0)>

;; Tracing, direct call fails
? (permutation-reverse (make-permutation 4 t))
0> Calling (PERMUTATION-REVERSE #<PERMUTATION #(0 1 2 3)>)
<0 PERMUTATION-REVERSE returned #<PERMUTATION #(3 2 1 0)>
#<PERMUTATION #(3 2 1 0)>

All the calls that exhibit the problem are FFI calls via CFFI.  For example,
(DEFUN PERMUTATION-REVERSE (P)
    (DECLARE)
    "Reverse the order of the elements of the permutation p."
    (LET NIL
      (COPY-CL-TO-C P)
      (LET ((#:CRETURN (FOREIGN-FUNCALL "gsl_permutation_reverse"
:POINTER (MPOINTER P) :VOID)))
	(DECLARE (IGNORE #:CRETURN))
	(SETF (CL-INVALID P) T)
	(VALUES P))))
(from a macro expansion)

The repository web site for GSLL is http://repo.or.cz/w/gsll.git

Is this a known problem?

Thanks,
Liam



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