re PR middle-end/43987 (type-punning causes broken binaries unless -O0 is used)

2010-05-06  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/43987
	* tree-ssa-structalias.c (could_have_pointers): For possibly
	address-taken variables force pointers to be recorded.
	(create_variable_info_for_1): Likewise.
	(push_fields_onto_fieldstack): Pass in wheter all fields
	must have pointers.
	(find_func_aliases): Query types instead of vars whether
	they contain pointers where appropriate.

	* gcc.c-torture/execute/pr43987.c: New testcase.
	* gcc.dg/torture/pta-escape-1.c: Adjust.
	* gcc.dg/tree-ssa/pta-escape-1.c: Likewise.
	* gcc.dg/tree-ssa/pta-escape-2.c: Likewise.
	* gcc.dg/tree-ssa/pta-escape-3.c: Likewise.
	* gcc.dg/ipa/ipa-pta-11.c: Likewise.

From-SVN: r159098

gcc/ChangeLog

+2010-05-06  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/43987
+	* tree-ssa-structalias.c (could_have_pointers): For possibly
+	address-taken variables force pointers to be recorded.
+	(create_variable_info_for_1): Likewise.
+	(push_fields_onto_fieldstack): Pass in wheter all fields
+	must have pointers.
+	(find_func_aliases): Query types instead of vars whether
+	they contain pointers where appropriate.
+
 2010-05-06  Jan Hubicka  <jh@suse.cz>
 
 	* cgraphbuild.c (record_reference_ctx): Add varpool_node.

gcc/testsuite/gcc.c-torture/execute/pr43987.c

+char B[256 * sizeof(void *)];
+typedef void *FILE;
+typedef struct globals {
+    int c;
+    FILE *l;
+} __attribute__((may_alias)) T;
+void add_input_file(FILE *file)
+{
+  (*(T*)&B).l[0] = file;
+}
+extern void abort (void);
+int main()
+{
+  FILE x;
+  (*(T*)&B).l = &x;
+  add_input_file ((void *)-1);
+  if ((*(T*)&B).l[0] != (void *)-1)
+    abort ();
+  return 0;
+}

gcc/testsuite/gcc.dg/ipa/ipa-pta-11.c

@@ -29,5 +29,5 @@ int main()
 /* It isn't clear if the escape if l is strictly necessary, if it were
    we should have i, r and s in ESCAPED as well.  */
 
-/* { dg-final { scan-ipa-dump "ESCAPED = { l k }" "pta" } } */
+/* { dg-final { scan-ipa-dump "ESCAPED = { ESCAPED NONLOCAL l k }" "pta" } } */
 /* { dg-final { cleanup-ipa-dump "pta" } } */

gcc/testsuite/gcc.dg/torture/pta-escape-1.c

@@ -30,5 +30,5 @@ main()
   return 0;
 }
 
-/* { dg-final { scan-tree-dump "ESCAPED = { i }" "alias" } } */
+/* { dg-final { scan-tree-dump "ESCAPED = { ESCAPED NONLOCAL i }" "alias" } } */
 /* { dg-final { cleanup-tree-dump "alias" } } */

gcc/testsuite/gcc.dg/tree-ssa/pta-escape-1.c

@@ -33,5 +33,5 @@ int main()
   return 0;
 }
 
-/* { dg-final { scan-tree-dump "ESCAPED, points-to vars: { x }" "alias" } } */
+/* { dg-final { scan-tree-dump "ESCAPED, points-to non-local, points-to vars: { x }" "alias" } } */
 /* { dg-final { cleanup-tree-dump "alias" } } */

gcc/testsuite/gcc.dg/tree-ssa/pta-escape-2.c

@@ -34,5 +34,5 @@ int main()
   return 0;
 }
 
-/* { dg-final { scan-tree-dump "ESCAPED, points-to vars: { x }" "alias" } } */
+/* { dg-final { scan-tree-dump "ESCAPED, points-to non-local, points-to vars: { x }" "alias" } } */
 /* { dg-final { cleanup-tree-dump "alias" } } */

gcc/testsuite/gcc.dg/tree-ssa/pta-escape-3.c

@@ -38,5 +38,5 @@ int main()
   return 0;
 }
 
-/* { dg-final { scan-tree-dump "ESCAPED, points-to vars: { x }" "alias" } } */
+/* { dg-final { scan-tree-dump "ESCAPED, points-to non-local, points-to vars: { x }" "alias" } } */
 /* { dg-final { cleanup-tree-dump "alias" } } */

gcc/tree-ssa-structalias.c

@@ -2959,7 +2959,11 @@ type_could_have_pointers (tree type)
 static bool
 could_have_pointers (tree t)
 {
-  return type_could_have_pointers (TREE_TYPE (t));
+  return (((TREE_CODE (t) == VAR_DECL
+	    || TREE_CODE (t) == PARM_DECL
+	    || TREE_CODE (t) == RESULT_DECL)
+	   && (TREE_PUBLIC (t) || DECL_EXTERNAL (t) || TREE_ADDRESSABLE (t)))
+	  || type_could_have_pointers (TREE_TYPE (t)));
 }
 
 /* Return the position, in bits, of FIELD_DECL from the beginning of its
@@ -4232,7 +4236,7 @@ find_func_aliases (gimple origt)
 	  /* If we are returning a value, assign it to the result.  */
 	  lhsop = gimple_call_lhs (t);
 	  if (lhsop
-	      && could_have_pointers (lhsop))
+	      && type_could_have_pointers (TREE_TYPE (lhsop)))
 	    {
 	      struct constraint_expr rhs;
 	      struct constraint_expr *lhsp;
@@ -4286,7 +4290,7 @@ find_func_aliases (gimple origt)
      operations with pointer result, others are dealt with as escape
      points if they have pointer operands.  */
   else if (is_gimple_assign (t)
-	   && could_have_pointers (gimple_assign_lhs (t)))
+	   && type_could_have_pointers (TREE_TYPE (gimple_assign_lhs (t))))
     {
       /* Otherwise, just a regular assignment statement.  */
       tree lhsop = gimple_assign_lhs (t);
@@ -4855,7 +4859,7 @@ var_can_have_subvars (const_tree v)
 
 static bool
 push_fields_onto_fieldstack (tree type, VEC(fieldoff_s,heap) **fieldstack,
-			     HOST_WIDE_INT offset)
+			     HOST_WIDE_INT offset, bool must_have_pointers_p)
 {
   tree field;
   bool empty_p = true;
@@ -4880,7 +4884,8 @@ push_fields_onto_fieldstack (tree type, VEC(fieldoff_s,heap) **fieldstack,
 	    || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE)
 	  push = true;
 	else if (!push_fields_onto_fieldstack
-		    (TREE_TYPE (field), fieldstack, offset + foff)
+		    (TREE_TYPE (field), fieldstack, offset + foff,
+		     must_have_pointers_p)
 		 && (DECL_SIZE (field)
 		     && !integer_zerop (DECL_SIZE (field))))
 	  /* Empty structures may have actual size, like in C++.  So
@@ -4906,6 +4911,7 @@ push_fields_onto_fieldstack (tree type, VEC(fieldoff_s,heap) **fieldstack,
 		&& !pair->has_unknown_size
 		&& !has_unknown_size
 		&& pair->offset + (HOST_WIDE_INT)pair->size == offset + foff
+		&& !must_have_pointers_p
 		&& !could_have_pointers (field))
 	      {
 		pair->size += TREE_INT_CST_LOW (DECL_SIZE (field));
@@ -4919,7 +4925,8 @@ push_fields_onto_fieldstack (tree type, VEC(fieldoff_s,heap) **fieldstack,
 		  pair->size = TREE_INT_CST_LOW (DECL_SIZE (field));
 		else
 		  pair->size = -1;
-		pair->may_have_pointers = could_have_pointers (field);
+		pair->may_have_pointers
+		  = must_have_pointers_p || could_have_pointers (field);
 		pair->only_restrict_pointers
 		  = (!has_unknown_size
 		     && POINTER_TYPE_P (TREE_TYPE (field))
@@ -5196,7 +5203,10 @@ create_variable_info_for_1 (tree decl, const char *name)
       bool notokay = false;
       unsigned int i;
 
-      push_fields_onto_fieldstack (decl_type, &fieldstack, 0);
+      push_fields_onto_fieldstack (decl_type, &fieldstack, 0,
+				   TREE_PUBLIC (decl)
+				   || DECL_EXTERNAL (decl)
+				   || TREE_ADDRESSABLE (decl));
 
       for (i = 0; !notokay && VEC_iterate (fieldoff_s, fieldstack, i, fo); i++)
 	if (fo->has_unknown_size