Re: [Sbcl-devel] turning off note

[Travis C. <tr...@cr...>]

Dimitry Gashinsky wrote:
> ; in: LAMBDA NIL
> ;     (SB-KERNEL:FLOAT-WAIT)
> ;
> ; note: deleting unreachable code

I'm not familiar with 'sb-aclrepl, but my guess is that this has to do with
the CLX hack in the sb-ext:with-timeout code.

(sb-ext:with-timeout 5
  (princ "foo))

expands into (timer.lisp):

(IF (> 5 0)
    (LET ((#:TIMER975 (MAKE-TIMER (LAMBDA () (CERROR "Continue" 'TIMEOUT)))))
      (SCHEDULE-TIMER #:TIMER975 5)
      (UNWIND-PROTECT (PROGN (PRINC "foo")) (UNSCHEDULE-TIMER #:TIMER975)))
    (PROGN (PRINC "foo")))

which clearly does in fact delete code.  This issue seems to generate a lot of
messages about deleting sb-kernel:float-wait when sb-ext:with-timeout is
combined with handler-bind and related macros.  The reason that the message
only shows up on x86 platforms is the handler-bind macro includes a special case
for x86 (defboot.lisp):

;; Wait for any float exceptions.
#!+x86 (float-wait))))

I am not familiar with why this particular hack for CLX was needed, and it
does seem to generate a substantial amount of needless notes and messages.

Without fixing this bug, this noise can be muffled by wrapping any calls to
sb-ext:with-timeout with:

(locally (declare (sb-ext:muffle-conditions sb-ext:code-deletion-note)) ...)

This is, of course, an ugly hack in and of itself.

Cheers,

-- Travis