alias.c (record_component_aliases): New function.

	* alias.c (record_component_aliases): New function.
	* tree.h: Clean up some declarations and comments.
	(record_component_aliases): New declaration.
	* tree.c (get_alias_set): If type and has alias set, use it.

From-SVN: r34078

4 files changed, 74 insertions, 22 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 1d5ee90..ea4f517 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+Mon May 22 06:57:49 2000  Richard Kenner  <kenner@vlsi1.ultra.nyu.edu>
+
+	* alias.c (record_component_aliases): New function.
+	* tree.h: Clean up some declarations and comments.
+	(record_component_aliases): New declaration.
+	* tree.c (get_alias_set): If type and has alias set, use it.
+
 2000-05-22  Richard Henderson  <rth@cygnus.com>
 
 	* simplify-rtx.c (simplify_ternary_operation): Try to simplify
diff --git a/gcc/alias.c b/gcc/alias.c
index 2f0392b8..9d3ff8b 100644
--- a/gcc/alias.c
+++ b/gcc/alias.c
@@ -271,8 +271,7 @@ insert_subset_children (node, data)
    not vice versa.  For example, in C, a store to an `int' can alias a
    structure containing an `int', but not vice versa.  Here, the
    structure would be the SUPERSET and `int' the SUBSET.  This
-   function should be called only once per SUPERSET/SUBSET pair.  At
-   present any given alias set may only be a subset of one superset.  
+   function should be called only once per SUPERSET/SUBSET pair. 
 
    It is illegal for SUPERSET to be zero; everything is implicitly a
    subset of alias set zero.  */
@@ -317,6 +316,48 @@ record_alias_subset (superset, subset)
 		     (splay_tree_key) subset, 0);
 }
 
+/* Record that component types of TYPE, if any, are part of that type for
+   aliasing purposes.  For record types, we only record component types
+   for fields that are marked addressable.  For array types, we always
+   record the component types, so the front end should not call this
+   function if the individual component aren't addressable.  */
+
+void
+record_component_aliases (type)
+     tree type;
+{
+  int superset = get_alias_set (type);
+  int subset;
+  tree field;
+
+  if (superset == 0)
+    return;
+
+  switch (TREE_CODE (type))
+    {
+    case ARRAY_TYPE:
+    case COMPLEX_TYPE:
+      subset = get_alias_set (TREE_TYPE (type));
+      if (subset != 0)
+	record_alias_subset (superset, subset);
+      break;
+
+    case RECORD_TYPE:
+    case UNION_TYPE:
+    case QUAL_UNION_TYPE:
+      for (field = TYPE_FIELDS (type); field != 0; field = TREE_CHAIN (field))
+	{
+	  subset = get_alias_set (TREE_TYPE (field));
+	  if (TREE_ADDRESSABLE (field) && subset != 0 && subset != superset)
+	    record_alias_subset (superset, subset);
+	}
+      break;
+
+    default:
+      break;
+    }
+}
+
 /* Inside SRC, the source of a SET, find a base address.  */
 
 static rtx
diff --git a/gcc/tree.c b/gcc/tree.c
index f532afe..a62e130 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -5621,10 +5621,15 @@ int
 get_alias_set (t)
      tree t;
 {
+  /* If we're not doing any lanaguage-specific alias analysis, just
+     assume everything aliases everything else.  */
   if (! flag_strict_aliasing || lang_get_alias_set == 0)
-    /* If we're not doing any lanaguage-specific alias analysis, just
-       assume everything aliases everything else.  */
     return 0;
+
+  /* If this is a type with a known alias set, return it since this must
+     be the correct thing to do.  */
+  else if (TYPE_P (t) && TYPE_ALIAS_SET_KNOWN_P (t))
+    return TYPE_ALIAS_SET (t);
   else
     return (*lang_get_alias_set) (t);
 }
diff --git a/gcc/tree.h b/gcc/tree.h
index ccbb9c3..1257d0a 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -2605,18 +2605,17 @@ extern void rest_of_type_compilation PARAMS ((tree, int));
 extern void push_obstacks_nochange PARAMS ((void));
 
 extern void permanent_allocation PARAMS ((int));
-
 extern void push_momentary PARAMS ((void));
-
 extern void clear_momentary PARAMS ((void));
-
 extern void pop_momentary PARAMS ((void));
-
 extern void end_temporary_allocation PARAMS ((void));
 
 /* Pop the obstack selection stack.  */
 extern void pop_obstacks PARAMS ((void));
 
+/* In alias.c */
+void record_component_aliases		PARAMS ((tree));
+
 /* In tree.c */
 extern int really_constant_p		PARAMS ((tree));
 extern void push_obstacks		PARAMS ((struct obstack *,
@@ -2654,10 +2653,12 @@ extern void dump_tree_statistics	PARAMS ((void));
 extern void print_obstack_statistics	PARAMS ((const char *,
 						struct obstack *));
 #ifdef BUFSIZ
-extern void print_obstack_name		PARAMS ((char *, FILE *, const char *));
+extern void print_obstack_name		PARAMS ((char *, FILE *,
+						 const char *));
 #endif
 extern void expand_function_end		PARAMS ((const char *, int, int));
 extern void expand_function_start	PARAMS ((tree, int));
+
 extern int real_onep			PARAMS ((tree));
 extern int real_twop			PARAMS ((tree));
 extern void start_identifier_warnings	PARAMS ((void));
@@ -2707,8 +2708,10 @@ extern void print_rtl			PARAMS ((FILE *, struct rtx_def *));
 /* In print-tree.c */
 extern void debug_tree			PARAMS ((tree));
 #ifdef BUFSIZ
-extern void print_node			PARAMS ((FILE *, const char *, tree, int));
-extern void print_node_brief		PARAMS ((FILE *, const char *, tree, int));
+extern void print_node			PARAMS ((FILE *, const char *, tree,
+						 int));
+extern void print_node_brief		PARAMS ((FILE *, const char *, tree,
+						 int));
 extern void indent_to			PARAMS ((FILE *, int));
 #endif
 
@@ -2718,8 +2721,10 @@ extern int apply_args_register_offset		PARAMS ((int));
 extern struct rtx_def *expand_builtin_return_addr
 	PARAMS ((enum built_in_function, int, struct rtx_def *));
 extern void do_pending_stack_adjust		PARAMS ((void));
-extern struct rtx_def *expand_assignment	PARAMS ((tree, tree, int, int));
-extern struct rtx_def *store_expr		PARAMS ((tree, struct rtx_def *,
+extern struct rtx_def *expand_assignment	PARAMS ((tree, tree, int,
+							 int));
+extern struct rtx_def *store_expr		PARAMS ((tree,
+							 struct rtx_def *,
 							int));
 extern void check_max_integer_computation_mode	PARAMS ((tree));
 
@@ -2732,21 +2737,15 @@ extern struct rtx_def *emit_line_note_force	PARAMS ((const char *, int));
 
 /* In calls.c */
 
-/* Flags used by special_function_p.  */
 extern int setjmp_call_p		PARAMS ((tree));
 
-/* In c-typeck.c */
+/* In front end.  */
+
 extern int mark_addressable		PARAMS ((tree));
 extern void incomplete_type_error	PARAMS ((tree, tree));
-
-/* In c-lang.c */
 extern void print_lang_statistics	PARAMS ((void));
-
-/* In c-common.c */
 extern tree truthvalue_conversion	PARAMS ((tree));
 extern void split_specs_attrs		PARAMS ((tree, tree *, tree *));
-
-/* In c-decl.c */
 #ifdef BUFSIZ
 extern void print_lang_decl		PARAMS ((FILE *, tree, int));
 extern void print_lang_type		PARAMS ((FILE *, tree, int));
@@ -2762,7 +2761,7 @@ extern void set_decl_abstract_flags	PARAMS ((tree, int));
 extern void output_inline_function	PARAMS ((tree));
 extern void set_decl_origin_self	PARAMS ((tree));
 
-/* In c-lex.c */
+/* In front end.  */
 extern void set_yydebug			PARAMS ((int));
 
 /* In stor-layout.c */