re PR tree-optimization/14784 ([Tree-ssa] alias analysis deficiency)

	PR tree-optimization/14784
	* tree-flow.h (struct var_ann_d): Add is_heapvar bit.
	* tree-ssa-structalias.c (get_constraint_for,
	intra_create_variable_infos): Set is_heapvar.
	* tree-ssa-operands.c (access_can_touch_variable): Do not handle
	non-heapvar pointer variables specially.

	* gcc.dg/alias-10.c: New test.

From-SVN: r117986

gcc/ChangeLog

+2006-10-23  Zdenek Dvorak <dvorakz@suse.cz>
+
+	PR tree-optimization/14784
+	* tree-flow.h (struct var_ann_d): Add is_heapvar bit.
+	* tree-ssa-structalias.c (get_constraint_for,
+	intra_create_variable_infos): Set is_heapvar.
+	* tree-ssa-operands.c (access_can_touch_variable): Do not handle
+	non-heapvar pointer variables specially.
+
 2006-10-23  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
 	PR middle-end/29335

gcc/testsuite/ChangeLog

+2006-10-23  Zdenek Dvorak <dvorakz@suse.cz>
+
+	PR tree-optimization/14784
+	* gcc.dg/alias-10.c: New test.
+
 2006-10-23  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
 	* gcc.dg/torture/builtin-sin-mpfr-1.c: New test.

gcc/testsuite/gcc.dg/alias-10.c

+/* For PR tree-optimization/14784  */
+
+/* { dg-do compile } */
+/* { dg-options "-O2 -funswitch-loops -fdump-tree-unswitch-details" } */
+
+typedef struct bitmap_element_def
+{
+  unsigned int indx;
+} bitmap_element;
+
+typedef struct bitmap_head_def {
+    bitmap_element *first;
+    int using_obstack;
+} bitmap_head;
+typedef struct bitmap_head_def *bitmap;
+
+bitmap_element *bitmap_free;
+
+void foo (bitmap head, bitmap_element *elt)
+{
+  while (1)
+    {
+      /* Alias analysis problems used to prevent us from recognizing
+	 that this condition is invariant.  */
+      if (head->using_obstack)
+	bitmap_free = elt;
+    }
+}
+
+
+/* { dg-final { scan-tree-dump-times "Unswitching" 1 "unswitch"} } */
+/* { dg-final { cleanup-tree-dump "unswitch" } } */

gcc/tree-flow.h

@@ -184,6 +184,9 @@ struct var_ann_d GTY(())
      in the v_may_def list.  */
   unsigned in_v_may_def_list : 1;
 
+  /* True for HEAP and PARM_NOALIAS artificial variables.  */
+  unsigned is_heapvar : 1;
+
   /* An artificial variable representing the memory location pointed-to by
      all the pointer symbols that flow-insensitive alias analysis
      (mostly type-based) considers to be aliased.  If the variable is

gcc/tree-ssa-operands.c

@@ -1151,11 +1151,11 @@ access_can_touch_variable (tree ref, tree alias, HOST_WIDE_INT offset,
 	   && flag_strict_aliasing
 	   && TREE_CODE (ref) != INDIRECT_REF
 	   && !MTAG_P (alias)
+	   && !var_ann (alias)->is_heapvar
 	   && (TREE_CODE (base) != INDIRECT_REF
 	       || TREE_CODE (TREE_TYPE (base)) != UNION_TYPE)
 	   && !AGGREGATE_TYPE_P (TREE_TYPE (alias))
 	   && TREE_CODE (TREE_TYPE (alias)) != COMPLEX_TYPE
-	   && !POINTER_TYPE_P (TREE_TYPE (alias))
 	   /* When the struct has may_alias attached to it, we need not to
 	      return true.  */
 	   && get_alias_set (base))

gcc/tree-ssa-structalias.c

@@ -2640,6 +2640,7 @@ get_constraint_for (tree t, VEC (ce_s, heap) **results)
 		  {		    
 		    heapvar = create_tmp_var_raw (ptr_type_node, "HEAP");
 		    DECL_EXTERNAL (heapvar) = 1;
+		    get_var_ann (heapvar)->is_heapvar = 1;
 		    if (referenced_vars)
 		      add_referenced_var (heapvar);
 		    heapvar_insert (t, heapvar);
@@ -4281,6 +4282,7 @@ intra_create_variable_infos (void)
 	    {
 	      heapvar = create_tmp_var_raw (TREE_TYPE (TREE_TYPE (t)), 
 					    "PARM_NOALIAS");
+	      get_var_ann (heapvar)->is_heapvar = 1;
 	      DECL_EXTERNAL (heapvar) = 1;
 	      if (referenced_vars)
 		add_referenced_var (heapvar);