[tree-ssa] Out of SSA status and issues

[Diego Novillo]

On Mon, 2003-05-12 at 14:45, Andrew MacLeod wrote:

> ie it would look something like this hacked up example:
>  
>       #   (*T.6)_13 = VDEF <(*T.6)_7>;
>       T.6_12 = T.2_8 + T.5_11;
> 
>       #   VUSE <T.6_12>;
>       i_14 = (*T.6)_13
> 
>       #   (*T.6)_22 = VDEF <(*T.6)_13>      
>       #   VUSE <T.6_12>
>       *T.6 = 30;
>     };
>   #   i_1 = PHI <i_6(0), (*T.6)_13(1)>;
> 
> Or is there a reason that copyprop would never happen?
>
Correctness wise?  No, there's no reason.  We can safely do the
propagation in this case.

But I wouldn't think it's efficient.  Pointer dereferences are bound to
be slower than a straight scalar reference.  The copy propagator in the
SSA renamer blocks propagation of INDIRECT_REF nodes.  The stand-alone
copy propagator should probably do the same.


Diego.