Ok, now in the easy case it seems to be working. I've handled most cases but I was wondering about one problem that I don't seem to be able to handle.
Let's say I want to rename register r6 to r15. I can safely do that in the block if I know that r15 is not used in that basic block and that r6 is not a live-out of the basic block. However, how to handle the case where r6 is a live-out ? Then, I would have to make sure that r15 is not defined in another basic block, thus destroying my new live-out value? It seems to be a cat-mouse game: - I could copy back r15 to r6 in that case though I would like to try to not have to do that because that requires an extra copy at the end of the block - I could go through all the blocks and rename all the r6s into r15s and vice-versa. As long as they are regular registers (and not the return register for example), it should work. I don't see how to do to handle this case neatly, any ideas? Thanks in advance, Jc On Tue, Apr 21, 2009 at 5:23 PM, Jean Christophe Beyler <jean.christophe.bey...@gmail.com> wrote: > Ok, I've been working at this and have actually made a bit of progress. > > - I now have a framework that finds the group of loads (let's assume > they stay together). > > - With the DF framework, I'm able to figure out which registers are > being used and which are free to be used. > > - I've pretty much got it to change the registers to the ones I want > but there are still some corner cases where it seems to be badly > handling that and actually changing the semantics of the program. > > I'll look into that, thanks, > Jc > > On Mon, Apr 20, 2009 at 3:01 PM, Eric Botcazou <ebotca...@adacore.com> wrote: >>> Ok, I'll try to look at that. Is there an area where I can see how to >>> initialize the framework and get information about which registers are >>> free? >> >> The API is in df.h, see for example ifcvt.c. >> >> -- >> Eric Botcazou >> >
