backend.fun

[Stephen Weeks]

> backend.fun is raising the no operand property again on a self-compile.  
> (Using the patch that Steve sent out last week.)1

Aha.  The bug is not in backend.fun.  The bug is in the definition of
Cps.PrimExp.maySideEffect.  Please replace the definition in cps-tree.fun with
the following.  This was actually the cause of the previous bug as well,
although my local fix to backend.fun caught some of the cases.

      fun maySideEffect(e: t): bool =
	 case e of
	    PrimApp{prim,...} => Prim.maySideEffect prim
	  | _ => false