http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52139
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-02-07 11:42:35 UTC --- Created attachment 26602 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26602 gcc47-pr52139.patch Ugh, this is ugly. The main problem is that delete_insn/remove_insn refuse to remove insns with NEXT_INSN (insn) == NULL_RTX (unless they are in the current sequence or in the sequence stack). Unfortunately in the cfglayout mode BB_END or end of bb->il.rtl->{header,footer} often/always have it NULL. In this testcase, we are merging two bbs where the first bb ends with an unconditional jump to the second and second bb contains switch table followed by barrier in its header, then deleted label, then NOTE_INSN_BASIC_BLOCK and that is the last insn in that bb. The first problem is that we delete_insn_chain in the header just all but the last insn, so BB_END (a) points to a BARRIER. And the second problem is that when removing the NOTE_INSN_BASIC_BLOCK note using delete_insn, NEXT_INSN (note) is NULL and thus remove_insn ICEs. The following ugly hacks fix it, but am not very happy about them.
