Hi all, I am trying to use define_split, but it seems to me that I don't understand how it is used. It says in the gccint.pdf (which I use as my tutorial (is there anything better or more up to date?)) that the combiner only uses the define_split if it doesn't find any define_insn to match. This is not clear to me: If there is no define_insn to match a pattern in the combine stage, then how is this pattern there in the first place? The only way I can think for it to happen is that such a pattern was created by the combiner itself (but it seems unreasonable to me that we now want to split what the combiner just combined). Can someone please explain this to me?
Thanks, Roy.
