rtl.h (MEM_READONLY_P): Replace RTX_UNCHANGING_P.

	* 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.

	* config/darwin.c (machopic_indirect_data_reference): Set
	MEM_READONLY_P instead of RTX_UNCHANGING_P.
	(machopic_indirect_call_target): Likewise.
	(machopic_legitimize_pic_address): Likewise.
	* config/arm/arm.c (legitimize_pic_address, arm_gen_load_multiple,
	arm_gen_store_multiple, arm_gen_movmemqi): Likewise.
	* config/arm/arm.md (load_multiple, store_multiple): Likewise.
	* config/frv/frv.md (symGOT2reg): Likewise.
	* config/i386/i386.c (legitimize_pic_address,
	legitimize_tls_address, ix86_split_to_parts): Likewise.
	* config/ia64/ia64.c (ia64_expand_tls_address): Likewise.
	* config/ia64/ia64.md (load_fptr): Likewise.
	* config/m32r/m32r.c (m32r_legitimize_pic_address): Likewise.
	* config/m68k/m68k.c (legitimize_pic_address): Likewise.
	* config/mcore/mcore.c (block_move_sequence): Likewise.
	* config/mn10300/mn10300.md (symGOT2reg): Likewise.
	* config/pa/pa.c (legitimize_pic_address): Likewise.
	* config/rs6000/rs6000.c (rs6000_legitimize_tls_address): Likewise.
	(rs6000_emit_move): Likewise.
	* config/s390/s390.c (legitimize_pic_address): Likewise.
	(legitimize_tls_address): Likewise.
	* config/s390/s390.md (casesi): Likewise.
	* config/sh/sh.c (prepare_move_operands, sh_reorg): Likewise.
	* config/sh/sh.md (symGOT2reg): Likewise.
	* config/sparc/sparc.c (legitimize_pic_address): Likewise.
	* config/v850/v850.md (casesi): Likewise.

	* config/ia64/ia64.c (gen_thread_pointer): Don't set RTX_UNCHANGING_P.
	* config/iq2000/iq2000.c (save_restore_insns): Likewise.
	* config/mips/mips.c (mips_restore_gp): Likewise.
	(mips_save_restore_reg, mips16_gp_pseudo_reg): Likewise.
	* config/sh/sh.c (sh_reorg): Likewise.

From-SVN: r86178

1 files changed, 11 insertions, 20 deletions

diff --git a/gcc/doc/rtl.texi b/gcc/doc/rtl.texi
index 210e182..a2dcfe7 100644
--- a/gcc/doc/rtl.texi
+++ b/gcc/doc/rtl.texi
@@ -735,27 +735,18 @@ prologues.
 resulted from an in-line function call.
 Stored in the @code{integrated} field and printed as @samp{/i}.
 
-@findex RTX_UNCHANGING_P
-@cindex @code{reg} and @samp{/u}
+@findex MEM_READONLY_P
 @cindex @code{mem} and @samp{/u}
-@cindex @code{concat} and @samp{/u}
-@cindex @code{unchanging}, in @code{reg} and @code{mem}
-@item RTX_UNCHANGING_P (@var{x})
-Nonzero in a @code{reg}, @code{mem}, or @code{concat} if the register or
-memory is set at most once, anywhere.  This does not mean that it is
-function invariant.
-
-GCC uses this flag to determine whether two references conflict.  As
-implemented by @code{true_dependence} in @file{alias.c} for memory
-references, unchanging memory can't conflict with non-unchanging memory;
-a non-unchanging read can conflict with a non-unchanging write; an
-unchanging read can conflict with an unchanging write (since there may
-be a single store to this address to initialize it); and an unchanging
-store can conflict with a non-unchanging read.  This means we must make
-conservative assumptions when choosing the value of this flag for a
-memory reference to an object containing both unchanging and
-non-unchanging fields: we must set the flag when writing to the object
-and clear it when reading from the object.
+@cindex @code{unchanging}, in @code{mem}
+@item MEM_READONLY_P (@var{x})
+Nonzero in a @code{mem}, if the memory is statically allocated and read-only.
+
+Read-only in this context never modified during the lifetime of the
+program, not necessarily in ROM or in write-disabled pages.  A common
+example of the later is a shared library's global offset table.  This
+table is initialized by the runtime loader, so the memory is technically
+writable, but after control is transfered from the runtime loader to the
+application, this memory will never be subsequently modified.
 
 Stored in the @code{unchanging} field and printed as @samp{/u}.