https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81766
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> --- So, it seems the CODE_LABEL in the first bb (successor of entry bb) is added by ix86_init_large_pic_reg called by called by ix86_init_pic_reg from: 5135 /* Perform target specific PIC register initialization. */ 5136 targetm.init_pic_reg (); in ira. In particular, the seq including the CODE_LABEL is added to: 8887 entry_edge = single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun)); 8888 insert_insn_on_edge (seq, entry_edge); 8889 commit_one_edge_insertion (entry_edge); so I'd say this is a backend bug, it should have created the extra bb, or called find_many_sub_basic_blocks (blocks); using a similar technique I've added in r250815, because it doesn't really know where the edge insertion will insert stuff. I think we were just extremely lucky no other pass in between ira and pro_and_epilogue was upset on the invalid RTL. That said, for 7.2 my preference is above patch, and for 8.0 I think we should fix the i386 backend (the only one that has targetm.init_pic_reg implemented). This stuff is weird anyway, do we really need it at the beginning of the function, even if we say shrink-wrap (i.e. shouldn't it be done in the prologue)?
