https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66790
--- Comment #30 from Eric Botcazou <ebotcazou at gcc dot gnu.org> --- > GEN and KILL are not the same for LR and MIR. > > 1) Sets and clobbers are handled differently. A set or clobber of r1 > _kills_ liveness, while for MIR sets _generate_ "initialized-ness" and only > clobbers kill it. > > 2) A use of r1 _creates_ liveness (which extends up, until it reaches the > sets for all reaching definitions of that use), while uses of r1 are > irrelevant for MIR. > > 3) For LR, GEN must override KILL if an insn has both a set and a use of r1. > For MIR, you cannot have a GEN (set) and a KILL (clobber) in the same insn. The issue is not LR vs MIR, it's the may-initialized part of LIVE vs MIR. It seem to me that the GEN and KILL of the may-initialized part of LIVE should be the same as those of MIR, since the difference between the 2 problems is only at the global level. Pierre-Marie's patch duplicates them, but ideally they should be factored and reused.
