Hi Andy,
> commit 59c557056cff1ce6146b4d689eeee922300b6278
> Author: Andy Wingo <[email protected]>
> Date: Tue Apr 10 15:56:23 2012 -0700
>
> peval: elide redundant predicates; eliminate some common subexpressions
>
> * module/language/tree-il/peval.scm (fold-constants): Returns #f instead
> of the expression, as all continuations handle #f themselves.
> (negate, bailout?, extract-facts, infer, infer-defined?)
> (infer-struct-vtable): New helpers.
I haven't looked at the code, but it sounds like you are trying to
eliminate redundant 'struct-vtable' checks. Unfortunately, it seems to
me that this cannot be done safely. In practice, the checks look like:
(eq? (struct-vtable s) <foo>)
Both of the values being compared here are fetched from mutable
locations. The 'struct-vtable' field is mutable, and <foo> is usually a
top-level variable that is also mutable. Furthermore, both of these
things are mutated in practice when a GOOPS class is redefined, IIUC.
Am I missing something?
Thanks,
Mark
