Greetings!
Waldek Hebisch <de...@fricas.org> writes:
> Looking more at the issue, I suspect that gcl is inlining definition
> of |*0;n;1;frame1;AUX|. I am not sure if Lisp standard allows
> such inlining (those are discrete definitions via separate evals,
> not parts of single file). In this case I can (re)define called
> function first and after that (re)define caller. Such change
> seem to fix this problem. However, FriCAS in many places
> assumes that redefinitions on the fly work as expected.
Yes, this is it. GCL collects a lot of information about compiled
functions and uses it (hopefully effectively) when optimizing the
caller. For example, 'reverse returns a sequence, and GCL will assume
this when compiling code that calls 'reverse, but if someone
subsequently changes 'reverse to return a number, that number will be
returned to the caller but will likely not be properly handled.
The ideal is if one can arrange to define (and optimally compile) the
callee before the caller. If the callee is expected to change, this
definition should be generic enough to encompass all allowed subsequent
changes.
Alternatively, one can set the assumed signature info with a
declaration:
(DEFUN |*0;n;1;frame1| (|envArg|)
(declare (ftype (function (t) t) |*0;n;1;frame1;AUX|))
(PROG (XG7)
(RETURN
(COND ((LETT XG7 (HGET |*0;n;1;frame1;AL| NIL)) XG7)
((QUOTE T) (HPUT |*0;n;1;frame1;AL| NIL (|*0;n;1;frame1;AUX|
|envArg|)))))))
One could use (function (t) integer) or (function (t) fixnum) as
appropriate. One can also declaim these declarations at the toplevel.
Other relevant function call declarations include (declare (notinline
fun)) and (declare (inline fun)). GCL will not inline the fun call
unless (declaim (inline fun)) was issued somewhere at the toplevel, but
one can override this setting with local declarations.
Not really relevant yet but on the horizon are other function
properties, including 'side-effects'. Many functions are known to
return atomic values given certain inputs, and further have no
'side-effects' as in making other changes to the global state. In such
situations GCL can skip the call altogether. I suppose we will have to
invent another declaration, as the spec allows, to override this
determination in the caller if/when this goes online.
One can see the current (default) signature info with (si::signature
'fun) or (si::signature #'fun).
With the |*0;n;1;frame1| above the test works as expected. Please let
me know if this clears the path for fricas or if we need to provide some
other facility.
Take care,
--
Camm Maguire c...@maguirefamily.org
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"The earth is but one country, and mankind its citizens." -- Baha'u'llah
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