SSA usage question

[Diego Novillo]

On Mon, 2004-06-07 at 12:32, Richard Kenner wrote:
>     OK, but what's really important is that the computation needed to get
>     'v' and 'x' must be explicitly expanded in the GIMPLE code.  
> 
> Sure, but that's what gimplify_expr will do, right?
> 
Yes.  In theory, all you do is request a gimple_val in the 2nd and 3rd
operand to the ARRAY_REF.

>     Even if it's simple enough to be trivially dead.  
> 
> It can't be dead.
> 
> But it can be constant.  Is it worth filling in these fields even in
> the constant case?
>
Yes, we do need the information.  If the constants come from something
like:

x = 3
v = 8
... a[i,x,v]
...
x = 3
v = 8
a[j,x,v] ...

The dead assignments will be cleaned up by the optimizers.


Diego.