[LLVMdev] some superoptimizer results

[John Regehr]

One last cost function idea: the cost is the number of inputs. So here the 
LHS has cost 1 and the RHS has cost 0:

%0:i32 = var
%1:i32 = shlnsw %0, 1:i32
%2:i32 = or 1:i32, %1
%3:i1 = slt %1, %2
infer %3
result 1:i1

The rationale, of course, is that these are likely to enable subsequent 
optimizations.  There aren't that many of these so perhaps a separate run 
would be reasonable?

John