[Gcl-devel] Chasing down a compiler bug

[Camm Maguire]

Greetings!  There is what in all likelihood appears to be a gcc
optimization bug on hppa which is erratically causing the acl2 full
test to fail when any optimization at all is enabled.  Some runs of
the book certifier pass, others fail, but when they fail, it is in
precisely the same point:

(defun remove-after-last-directory-separator (p)
  (let* ((p-rev (reverse p))
         (posn (position *directory-separator* p-rev)))
    (if posn
        (subseq p 0 (1- (- (length p) posn)))
      (er hard 'remove-after-last-directory-separator
          "Implementation error!  Unable to handle a directory string."))))

Evidently posn is nil at times when it shouldn't be.

I want to make sure this is not gcl's fault, preferably before
release. 

In any case, acl2 is so well isolated from the underlying lisp that I
am hard pressed to simply set a gdb break point at this failure.  I
can't use format, error, anything I can trap.  Do you have any advice? 

Take care,
-- 
Camm Maguire                                            address@hidden
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