Re: Might a -native-semantics switch, forcing native target optimization semantics, be reasonable?

[Mike Stump <mrs at apple dot com>]

On Dec 31, 2005, at 9:26 PM, Paul Schlie wrote:
> be able define NULL as being some value other than 0.

Do you have a specific chip in mind you want to do this for?  Why  
would you want to do this?  How many users would benefit from having  
done this?

> - enable the specification of arithmetic pointer and integer overflow
>   semantics, not limited to invoking an undefined or modulo  
> results, as
>   being able to support saturating integer arithmetic optimization  
> seems
>   increasingly attractive as signal processing becomes more pervasive.

Yes, but you didn't answer my other two question.  Anyway, what  
hardware does only saturating arithmetic?  If it does both, would you  
want + to be saturating?  If so, why?  How would you then want to get  
non-saturating arithmetic?

Saturating arithmetic is a good example of where the code should use  
a specialized form to denote the operation, and that form then makes  
the code completely portable, so, I cannot fathom why you'd want it  
in this class.

What compilers do this today?  What code bases do this today?

If none and none, why would we want to?

We don't yet have a clue why you want this, could you give us the  
real reason.  Theoretic beauty?  You wanna sell a chip that does this  
and have a compiler for it?  You want to define a new language  
because you think it'd be cool?  You want gcc to match the needs of  
DSP programmers better?

> - enable the specification of the result/behavior of a shift greater
>   than the width of a operand

This one I actually understand.