http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54963
--- Comment #5 from Oleg Endo <olegendo at gcc dot gnu.org> 2012-10-29 11:13:19 UTC --- (In reply to comment #4) > (In reply to comment #3) > > Created attachment 28551 [details] > > Proposed patch > > > > This patch fixes the problem, by using 'emit_move_insn' instead of manually > > doing the DImode reg copy. > > Does the pattern in negdi_cond > > emit_insn (gen_negc (low_dst, low_src)); > emit_label_after (skip_neg_label, emit_insn (gen_negc (high_dst, > high_src))); > > work in the problematic situation? Perhaps I've missed something. Ugh, you're right. The negdi will go wrong if input and output regs overlap. I guess making the output operand a "=&r" for DImode should fix the issue (as it's done in the adddi3 or subdi3 patterns). Moreover, I think it should be OK to split up the absdi pattern before reload, except for negdi_cond. I'll try that out.
