gcc/
* rtl.h (PREV_INSN): Split macro in two: the existing one,
for rvalues, and...
(SET_PREV_INSN): New macro, for use as an lvalue.
(NEXT_INSN, SET_NEXT_INSN): Likewise.
* caller-save.c (save_call_clobbered_regs): Convert lvalue use of
PREV_INSN/NEXT_INSN into SET_PREV_INSN/SET_NEXT_INSN.
* cfgrtl.c (try_redirect_by_replacing_jump): Likewise.
(fixup_abnormal_edges): Likewise.
(unlink_insn_chain): Likewise.
(fixup_reorder_chain): Likewise.
(cfg_layout_delete_block): Likewise.
(cfg_layout_merge_blocks): Likewise.
* combine.c (update_cfg_for_uncondjump): Likewise.
* emit-rtl.c (link_insn_into_chain): Likewise.
(remove_insn): Likewise.
(delete_insns_since): Likewise.
(reorder_insns_nobb): Likewise.
(emit_insn_after_1): Likewise.
* final.c (rest_of_clean_state): Likewise.
(final_scan_insn): Likewise.
* gcse.c (can_assign_to_reg_without_clobbers_p): Likewise.
* haifa-sched.c (concat_note_lists): Likewise.
(remove_notes): Likewise.
(restore_other_notes): Likewise.
(move_insn): Likewise.
(unlink_bb_notes): Likewise.
(restore_bb_notes): Likewise.
* jump.c (delete_for_peephole): Likewise.
* optabs.c (emit_libcall_block_1): Likewise.
* reorg.c (emit_delay_sequence): Likewise.
(fill_simple_delay_slots): Likewise.
* sel-sched-ir.c (sel_move_insn): Likewise.
(sel_remove_insn): Likewise.
(get_bb_note_from_pool): Likewise.
* sel-sched.c (move_nop_to_previous_block): Likewise.
* config/bfin/bfin.c (reorder_var_tracking_notes): Likewise.
* config/c6x/c6x.c (gen_one_bundle): Likewise.
(c6x_gen_bundles): Likewise.
(hwloop_optimize): Likewise.
* config/frv/frv.c (frv_function_prologue): Likewise.
(frv_register_nop): Likewise.
* config/ia64/ia64.c (ia64_init_dfa_pre_cycle_insn): Likewise.
(ia64_reorg): Likewise.
* config/mep/mep.c (mep_reorg_addcombine): Likewise.
(mep_make_bundle): Likewise.
(mep_bundle_insns): Likewise.
* config/picochip/picochip.c (reorder_var_tracking_notes): Likewise.
* config/tilegx/tilegx.c (reorder_var_tracking_notes): Likewise.
* config/tilepro/tilepro.c (reorder_var_tracking_notes): Likewise.