re PR tree-optimization/20458 (structure aliasing causes wrong code)

2005-03-14  Daniel Berlin <dberlin@dberlin.org>

	Fix PR tree-optimization/20458

	* tree-flow-inline.h (mark_call_clobbered): Don't fiddle
	DECL_EXTERNAL on STRUCT_FIELD tags.
	(clear_call_clobbered): Ditto.
	* tree-ssa-operands.c (note_addressable): Make sure the original
	variable doesn't slip into the addressable list if we have
	subvars.
	* tree-tailcall.c (suitable_for_tail_opt_p): Look at STRUCT_FIELD
	tags too.

From-SVN: r96462

gcc/ChangeLog

+2005-03-14  Daniel Berlin <dberlin@dberlin.org>
+
+	Fix PR tree-optimization/20458
+
+	* tree-flow-inline.h (mark_call_clobbered): Don't fiddle
+	DECL_EXTERNAL on STRUCT_FIELD tags.
+	(clear_call_clobbered): Ditto.
+	* tree-ssa-operands.c (note_addressable): Make sure the original
+	variable doesn't slip into the addressable list if we have
+	subvars.
+	* tree-tailcall.c (suitable_for_tail_opt_p): Look at STRUCT_FIELD
+	tags too.
+	
 2005-03-14  Geoffrey Keating  <geoffk@apple.com>
 
 	* doc/cppopts.texi (-fexec-charset): Add concept index entry.

gcc/testsuite/g++.dg/tree-ssa/pr20458.C

+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+/* The tail call optimization would inapproriately tail call the 
+   destructors due to not recognizing a call clobbered variable */
+namespace std
+{
+	class locale
+	{
+		public:
+			locale();
+			~locale();
+	};
+}
+
+struct B
+{
+	std::locale _M_buf_locale;
+	virtual ~B() {}
+};
+
+struct C : public B
+{
+	char *s;
+};
+
+void foo ()
+{
+	C c;
+}
+
+int main()
+{
+	foo ();
+	return 0;
+}
+

gcc/tree-flow-inline.h

@@ -619,7 +619,7 @@ mark_call_clobbered (tree var)
      variable.  This is because the pointer that VAR represents has
      been found to point to either an arbitrary location or to a known
      location in global memory.  */
-  if (ann->mem_tag_kind != NOT_A_TAG)
+  if (ann->mem_tag_kind != NOT_A_TAG && ann->mem_tag_kind != STRUCT_FIELD)
     DECL_EXTERNAL (var) = 1;
   bitmap_set_bit (call_clobbered_vars, ann->uid);
   ssa_call_clobbered_cache_valid = false;
@@ -631,7 +631,7 @@ static inline void
 clear_call_clobbered (tree var)
 {
   var_ann_t ann = var_ann (var);
-  if (ann->mem_tag_kind != NOT_A_TAG)
+  if (ann->mem_tag_kind != NOT_A_TAG && ann->mem_tag_kind != STRUCT_FIELD)
     DECL_EXTERNAL (var) = 0;
   bitmap_clear_bit (call_clobbered_vars, ann->uid);
   ssa_call_clobbered_cache_valid = false;

gcc/tree-ssa-operands.c

@@ -1729,7 +1729,7 @@ note_addressable (tree var, stmt_ann_t s_ann)
       if (s_ann->addresses_taken == NULL)
 	s_ann->addresses_taken = BITMAP_GGC_ALLOC ();      
       
-      bitmap_set_bit (s_ann->addresses_taken, var_ann (var)->uid);
+
       if (var_can_have_subvars (var)
 	  && (svars = get_subvars_for_var (var)))
 	{
@@ -1737,6 +1737,8 @@ note_addressable (tree var, stmt_ann_t s_ann)
 	  for (sv = svars; sv; sv = sv->next)
 	    bitmap_set_bit (s_ann->addresses_taken, var_ann (sv->var)->uid);
 	}
+      else
+	bitmap_set_bit (s_ann->addresses_taken, var_ann (var)->uid);
     }
 }
 

gcc/tree-tailcall.c

@@ -137,14 +137,15 @@ suitable_for_tail_opt_p (void)
   if (current_function_stdarg)
     return false;
 
-  /* No local variable should be call-clobbered.  We ignore any kind
-     of memory tag, as these are not real variables.  */
+  /* No local variable nor structure field should be call-clobbered.  We
+     ignore any kind of memory tag, as these are not real variables.  */
   for (i = 0; i < (int) VARRAY_ACTIVE_SIZE (referenced_vars); i++)
     {
       tree var = VARRAY_TREE (referenced_vars, i);
 
       if (!(TREE_STATIC (var) || DECL_EXTERNAL (var))
-	  && var_ann (var)->mem_tag_kind == NOT_A_TAG
+	  && (var_ann (var)->mem_tag_kind == NOT_A_TAG
+	      || var_ann (var)->mem_tag_kind == STRUCT_FIELD)
 	  && is_call_clobbered (var))
 	return false;
     }