Re: array type declaration problems

On Sun, 21 Sep 2003, james anderson wrote:

>
> this function
>
> (defun matrix-identity (&optional (nm (matrix) result-p))
>    "initialize an optional argument matrix to the diagonal = 1.0d0.
>     if no result matrix is provided a new matrix is constructed."
>    #|(declare  (optimize (speed 3) (safety 0)) (type double-matrix nm))|#
>    (when result-p (assert-type nm double-matrix))
>    (let ((i-max (array-dimension nm 0))
>          (j-max (array-dimension nm 1)))
>      (declare (type fixnum i-max j-max))
>      (dotimes (i i-max)
>        (dotimes (j j-max)
>          (if (= i j)
>            (setf (aref nm i j) 1.0d0)
>            (when result-p                  ; a defaulted result is
> already initialized
>              (setf (aref nm i j) 0.0d0))))))
>    nm)
>
> produces incorrect result if the type declaration is included.
> independent of the optimize declaration.
>

Sorry for not responding sooner.

This is fixed in CVS.  The compiler was sort of unsure about whether or
not (SETF (AREF a i j) ...) has side-effects, so it generated correct code
and a branch instruction that skipped that code completely.