birthpoints in rtl.

[Diego Novillo]

On 3/1/08 5:13 AM, Jan Hubicka wrote:

> while I am with Diego that would preffer PHI nodes on side especially in
> FUD chain where rest of your SSA is on side too.  But if we go with the
> extra instruction scheme, I think you are much better to use RTL USE
> instruction.  The moves are generated by target machinery and can do
> funny things, like clobbering flags or whatever.  USEs are transparent
> this way.

One step at a time, though.  Changing the current dense UD chains in DF 
should be fairly easy.  However, going to a rewriting SSA form in RTL is 
going to be more involved.  We may even need to do the same split we do 
in GIMPLE and have both a rewriting form and a FUD-chain form.


Diego.