Ada subtypes and base types

[Jeffrey A Law]

On Wed, 2006-02-22 at 13:25 -0500, Richard Kenner wrote:
>      When I speak about doing arithmetic in a type, I'm referring to the
>      type of the expression & its input operands in a gimplified
>      expression.  At that point I do not care about base types or anything
>      like that.  All that should matter is TREE_TYPE (expr), nothing more,
>      nothing less.  How the inputs are converted or how the output is later
>      converted is not a concern -- all that matters is TREE_TYPE (expr) in
>      a gimplified tree.
> 
>      Can we agree on that?
> 
> Yes.
> 
> The base type reference is that I'm *also* saying "If you see an arithmetic
> node where TREE_TYPE is *not* a base type, there's a bug someplace that
> has to be fixed". (Well, with the exception of such things as sizetypes
> or subtypes that don't actually change anything.)
Just to make sure I've dotted the i's and crossed the t's, this
is not what's happening when we hang in VRP when compiling a-textio.

We convert the incoming object from natural___XDLU_0___2147483647
into its base type, perform the addition in the base type, then
convert back to XDLU_0_2147483647.

Jeff