Use of DI mode on 32-bit hosts

[Frank Ch. Eigler]

Hi -


On Mon, Jun 02, 2003 at 03:04:21PM -0700, Doug Evans wrote:
>  > I guess I don't see the abstraction and simplicity this
>  > indirection is to provide.  Do you have an example?
> 
> - I'd rather have one version of "add" for sparc 32/64

I would rather use macros that expand to SI or DI as appropriate
for the two different targets, or perhaps use DI only (and rely
on implicit truncation for 32-bit hardware registers).

> - I'd rather write 'IAI in the .scm sources when refering to 'pc
>   than doing something else

Likewise -- the PC register is likewise an inherently target-sized
quantity.

This whole argument sounds like going backward from the SI-vs-USI
issue from a few weeks ago.  It encodes in the type some notion of
purpose, or even a deliberate lack of specificity, instead of
leaving these solely in the operators.


>  > In what circumstances do you consider it reasonable for cgen
>  > model files to deal with host data types/sizes?
> 
> [...]
> Sometimes the code will need a mode but imposing a specific
> width muddies the waters.  If one wanted to write some rtl
> that looped over something, picking one of QI/HI/SI/DI
> may be less appealing than "just give me a big enough int". [...]

Not to me...  Given the low level nature of modelling semantics
in rtl, I don't consider it natural to pick "a big enough" int.


- FChE
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