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.
