[Timber] 64 bit?

[Johan Nordlander]

> Also, since this is supposed to be a bit of a bare metal run time  
> system, wouldn't it make sense to have Int match the size of the  
> architecture? It would remove a superfluous (IMO) abstraction.

It is reasonable, although the big drawback is that the meaning of  
programs will then be platform-dependent in a very unfortunate way.   
For example, the expression 60000 + 10000 > 60000 will be true on some  
platforms but false on 16-bit architectures.  I have no problem with  
the wrap-around semantics for integers (it's what we want!), but it  
should be specified by the language to mean the same thing on all  
platforms.  Programs written with the specific aim to fit well on  
smaller/bigger architectures should instead indicate this by using  
integer types with other wrap-around limits (we ought to add Int8,  
Int16 and Int64 as primitives).

Using the machine-dependent WORD type when casting to and from  
pointers is a different thing -- this change doesn't affect the  
meaning of any Timber programs.

-- Johan

> On Sun, May 24, 2009 at 10:54 AM, Johan Nordlander <johan.nordlander at ltu.se 
> > wrote:
> Some experiments have been made (although no code were checked in),  
> and they mostly involved fixing rts.h.  The underlying problem is,  
> though, that there's a risk parts of the code silently assume that  
> an Int is of the same size as a polymorphic parameter (that is, the  
> size of a pointer).  And ideally we would like to keep the Int size  
> at 32 bits in order to preserve platform independence, and introduce  
> an Int64 type for those cases this size is needed.
>
> So it's essentially a matter of searching the source code for any  
> such size dependencies, and perhaps also extended it with Int types  
> of other common sizes.  I can't foresee any deep technical  
> difficulies, it's just tedious work.
>
> You're welcome to give it a try!
>
> -- Johan
>
>
> I haven't looked too deeply into the source, but it would appear  
> that the bulk of the 64-bit problems are relegated to rts.h.
> Is there any effort under way to address this? If not, I will take a  
> whack at correcting it. If there is some experimental code out  
> there, I'd be happy to test it on my 64 bit fedora machine.
>
> -- 
> We can't solve problems by using the same kind of thinking we used  
> when we created them.
>   - A. Einstein
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> We can't solve problems by using the same kind of thinking we used  
> when we created them.
>    - A. Einstein
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