Senthil Kumar via Gcc-patches <gcc-patches@gcc.gnu.org> writes: > Hi, > > I'm working on converting the AVR backend to MODE_CC, following > the steps described for case #2 in the CC0 transition wiki page, > and I've implemented the first three bullet > points (https://github.com/saaadhu/gcc-avr-cc0/tree/avr-cc0-squashed). With > the below patch, there are zero regressions (for mega and xmega > subarchs) compared to the current mainline, as of yesterday. > > The wiki suggests using post-reload splitters, so that's the > direction I took, but I ran into an issue where split_insn > bails out early if RTX_FRAME_RELATED_P is true - this means > that splits for REG_CC clobbering insns with > RTX_FRAME_RELATED_P will never execute, resulting in a > could-not-split insn ICE in the final stage. > > I see that the recog.c:peep2_attempt allows splitting of a > RTX_FRAME_RELATED_P insn, provided the result of the split is a > single insn. Would it be ok to modify try_split also to > allow those kinds of insns (tentative patch attached, code > copied over from peep2_attempt, only setting old and new_insn)? Or is there > a different approach to fix this?
I agree there's no obvious reason why splitting to a single insn should be rejected but a peephole2 to a single instruction should be OK. And reusing the existing, tried-and-tested code is the way to go. But could you split the code out of peep2_attempt into a subroutine (probably still in recog.c) and reuse it in try_split? BTW, just to check: is your email address in MAINTAINERS still correct? Thanks, Richard
