invoke.texi (-fstrict-aliasing): Document.

	* invoke.texi (-fstrict-aliasing): Document.
	* rtl.texi (MEM_ALIAS_SET): Document.
	* flags.h (flag_strict_aliasing): Declare.
	* toplev.c (flag_strict_aliasing): Define.
	(f_options): Add -strict-aliasing.
	(main): Set flag_strict_aliasing if -O2 or higher.
	* tree.h (tree_type): Add alias_set field.
	(TYPE_ALIAS_SET): New macro.
	(TYPE_ALIAS_SET_KNOWN_P): Likewise.
	(get_alias_set): Declare.
	* tree.c (lang_get_alias_set): Define.
	(make_node): Initialize TYPE_ALIAS_SET.
	(get_alias_set): New function.
	* print-tree.c (print_node): Dump the alias set for a type.
	* c-tree.h (c_get_alias_set): Declare.
	* c-common.c (c_get_alias_set): New function.
	* c-decl.c (init_decl_processing): Set lang_get_alias_set.
	* expr.c (protect_from_queue): Propogage alias sets.
	(expand_assignment): Calculate alias set for new MEMs.
	(expand_expr): Likewise.
	* function.c (put_var_into_stack): Likewise.
	(put_reg_into_stack): Likewise.
	(gen_mem_addressof): Likewise.
	(assign_parms): Likewise.
	* stmt.c (expand_decl): Likewise.
	* varasm.c (make_decl_rtl): Eliminate redundant clearing of
	DECL_RTL.  Calculate alias set for new MEMs.
	* rtl.def (REG): Add dummy operand.
	(MEM): Add extra operand to store the MEM_ALIAS_SET.
	* rtl.h (MEM_ALIAS_SET): New macro.
	(gen_rtx_MEM): Declare.
	* emit-rtl.c (gen_rtx_MEM): New function.
	* gengenrtl.c (sepcial_rtx): Make MEMs special.
	* alias.c (CHECK_ALIAS_SETS_FOR_CONSISTENCY): New macro.
	(DIFFERENT_ALIAS_SETS_P): Likewise.
	(canon_rtx): Propogate the alias set to the new MEM.
	(true_dependence): Check the alias sets.
	(anti_dependence): Likewise.
	(output_dependence): Likewise.
	* explow.c (stabilize): Progoate alias sets.
	* integrate.c (copy_rtx_and_substitute): Likewise.
	* final.c (alter_subreg): Make sure not to leave MEM_IN_STRUCT_P
	in an unpredictable state.  Propogate alias sets.
	* reload1.c (reload): Clear MEM_ALIAS_SET for new MEMs about which
	we have no alias information.

From-SVN: r20719

1 files changed, 21 insertions, 0 deletions

diff --git a/gcc/tree.c b/gcc/tree.c
index baf4551..de5a179 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -261,6 +261,10 @@ static int next_decl_uid;
 /* Unique id for next type created.  */
 static int next_type_uid = 1;
 
+/* The language-specific function for alias analysis.  If NULL, the
+   language does not do any special alias analysis.  */
+int (*lang_get_alias_set) PROTO((tree));
+
 /* Here is how primitive or already-canonicalized types' hash
    codes are made.  */
 #define TYPE_HASH(TYPE) ((unsigned long) (TYPE) & 0777777)
@@ -1112,6 +1116,9 @@ make_node (code)
 #ifdef SET_DEFAULT_TYPE_ATTRIBUTES
       SET_DEFAULT_TYPE_ATTRIBUTES (t);
 #endif
+      /* Note that we have not yet computed the alias set for this
+	 type.  */
+      TYPE_ALIAS_SET (t) = -1;
       break;
 
     case 'c':
@@ -5019,3 +5026,17 @@ expr_check (node, ignored, file, line, nofatal)
   return node;
 }
 #endif
+
+/* Return the alias set for T, which may be either a type or an
+   expression.  */
+
+int get_alias_set (t)
+     tree t;
+{
+  if (!flag_strict_aliasing || !lang_get_alias_set)
+    /* If we're not doing any lanaguage-specific alias analysis, just
+       assume everything aliases everything else.  */
+    return 0;
+  else
+    return (*lang_get_alias_set) (t);
+}