* rtl.h (MEM_READONLY_P): Replace RTX_UNCHANGING_P.
* alias.c (true_dependence): Update to match new semantics.
(canon_true_dependence, write_dependence_p): Likewise.
(anti_dependence, output_dependence): Update write_dependence_p args.
(unchanging_anti_dependence): Remove.
* calls.c (purge_mem_unchanging_flag): Remove.
(fixup_tail_calls): Don't call it.
(expand_call): Don't add unchanging memory to function usage.
* expr.c (emit_block_move_via_libcall): Likewise.
(clear_storage_via_libcall): Don't clobber RTX_UNCHANGING_P mems.
(get_subtarget): Don't use RTX_UNCHANGING_P.
(expand_assignment, store_constructor, expand_expr_real_1): Likewise.
(do_tablejump): Set MEM_READONLY_P, not RTX_UNCHANGING_P.
* combine.c (get_last_value_validate): Use MEM_READONLY_P.
* cse.c (insert): Don't use RTX_UNCHANGING_P.
(cse_insn, canon_hash): Use MEM_READONLY_P.
* emit-rtl.c (set_mem_attributes_minus_bitpos): Use MEM_READONLY_P
instead of RTX_UNCHANGING_P.
* explow.c (maybe_set_unchanging): Remove.
* expr.h (maybe_set_unchanging): Remove.
* flow.c (insn_dead_p, mark_used_regs): Use anti_dependence.
* function.c (assign_stack_temp_for_type): Don't use RTX_UNCHANGING_P.
(assign_parm_setup_reg, expand_function_start): Likewise.
* integrate.c (copy_rtx_and_substitute): Likewise.
* ra-rewrite.c (emit_colors): Likewise.
* regmove.c (copy_src_to_dest, regmove_optimize): Likewise.
(fixup_match_1): Likewise.
* reload1.c (reload, alter_reg): Likewise.
* local-alloc.c (validate_equiv_mem): Check MEM_READONLY_P,
not RTX_UNCHANGING_P.
(equiv_init_varies_p): Likewise.
* loop-invariant.c (check_maybe_invariant): Likewise.
* resource.c (mark_referenced_resources, mark_set_resources): Likewise.
* loop.c (note_addr_stored): Likewise.
(prescan_loop): Likewise. Don't check function usage for clobbered
unchanging memory.
* rtlanal.c (rtx_unstable_p): Check MEM_READONLY_P,
not RTX_UNCHANGING_P.
(rtx_varies_p, modified_between_p, modified_in_p): Likewise.
* varasm.c (force_const_mem): Likewise.
* stmt.c (expand_decl): Don't set RTX_UNCHANGING_P.
* web.c (entry_register): Likewise.
* tree-gimple.h (get_base_address): Move decl ...
* tree.h: ... here.
* doc/rtl.texi (MEM_READONLY_P): Replace RTX_UNCHANGING_P.
* config/alpha/alpha.c (alpha_set_memflags_1): Rewrite to be
called via for_each_rtx. Copy MEM_SCALAR_P, MEM_NOTRAP_P too.
(alpha_set_memflags): Update to match.