It would be nice to remove other magic numbers from the patch as well. I have seen several "4" hardcoded in the patch (mostly in SB-VM part of it). It looks like the 32-bit pointer size, but this is not a justification. 

In general (not in this patch), magic numbers are quite common in SBCL's SB-VM code, and this is a problem. When I look at this code from call.lisp, I wonder why don't we name the things properly?

(+ (if named 5 0)
      (if variable 19 1)
        (if (eq return :tail) 0 10)
            (if (eq return :unknown) 25 0))


2010/12/30 Alastair Bridgewater <>

In the definition for +win32-tib-arbitrary-field-offset+, there is no
commentary as to what this offset corresponds to, it ends up just
being a magic number.