PR 23046. Folding predicates involving TYPE_MAX_VALUE/TYPE_MIN_VALUE (Ada RFC)

[Robert Dewar]

Laurent GUERBY wrote:

> My understanding is that VRP (the compiler) is free to remove all other
> language mandated range checks based on type min/max information but has
> to keep the ones generated for 'Valid. 

and any implicit validity checks, and for gnat, validity checks from
-gnatVa
> 
> An implementation model could be for the front-end to generate for each
> family of scalar type T a function Base_Type_Internal_Valid (X, Min,
> Max : in Base_Type_Of_T) return Boolean, generate a call to it at all
> 'Valid uses and then tell the compiler to never do any inlining at all
> on such generated function.

sounds ver inefficient, remember that many left hand side array
references require implicit validity checks.
> 
> Since I think there are not that many scalar base types around, I guess
> such functions could even be included in the Ada RTS and not generated
> on the fly.
> 
> Of course performance wouldn't be as good as possible, but if
> there's no other way...
> 
> Laurent
>