re PR middle-end/41006 (verify_stmts failed: error: non-trivial conversion at assignment)

2009-08-10  Richard Guenther  <rguenther@suse.de>

	PR middle-end/41006
	* tree-ssa.c (useless_type_conversion_p_1): Fold into ...
	(useless_type_conversion_p): ... here.  Require pointer targets
	to be compatible.

	* gcc.c-torture/compile/pr41006-1.c: New testcase.
	* gcc.c-torture/compile/pr41006-2.c: Likewise.

From-SVN: r150621

gcc/ChangeLog

+2009-08-10  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/41006
+	* tree-ssa.c (useless_type_conversion_p_1): Fold into ...
+	(useless_type_conversion_p): ... here.  Require pointer targets
+	to be compatible.
+
 2009-08-10  Dodji Seketeli  <dodji@redhat.com>
 
 	PR c++/40866

gcc/testsuite/ChangeLog

+2009-08-10  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/41006
+	* gcc.c-torture/compile/pr41006-1.c: New testcase.
+	* gcc.c-torture/compile/pr41006-2.c: Likewise.
+
 2009-08-10  Janus Weil  <janus@gcc.gnu.org>
 
 	PR fortran/40940

gcc/testsuite/gcc.c-torture/compile/pr41006-1.c

+typedef int (*FARPROC)();
+
+typedef int (*LPFN_ACCEPTEX)(void*);
+static LPFN_ACCEPTEX acceptex_fn;
+
+int xWSAIoctl(void*);
+static void get_fn(FARPROC* fn)
+{
+    FARPROC func;
+    if (!xWSAIoctl( &func))
+        *fn = func;
+}
+
+void get_fn_pointers()
+{
+    get_fn((FARPROC*)&acceptex_fn);
+}

gcc/testsuite/gcc.c-torture/compile/pr41006-2.c

+typedef int *FARPROC;
+static int * __restrict__ acceptex_fn;
+
+int xWSAIoctl(void*);
+static void get_fn(FARPROC* fn)
+{
+  FARPROC func;
+  if (!xWSAIoctl( &func))
+    *fn = func;
+}
+
+void get_fn_pointers()
+{
+  get_fn((FARPROC*)&acceptex_fn);
+}

gcc/tree-ssa.c

@@ -844,10 +844,31 @@ delete_tree_ssa (void)
   redirect_edge_var_map_destroy ();
 }
 
-/* Helper function for useless_type_conversion_p.  */
+/* Return true if the conversion from INNER_TYPE to OUTER_TYPE is a
+   useless type conversion, otherwise return false.
 
-static bool
-useless_type_conversion_p_1 (tree outer_type, tree inner_type)
+   This function implicitly defines the middle-end type system.  With
+   the notion of 'a < b' meaning that useless_type_conversion_p (a, b)
+   holds and 'a > b' meaning that useless_type_conversion_p (b, a) holds,
+   the following invariants shall be fulfilled:
+
+     1) useless_type_conversion_p is transitive.
+	If a < b and b < c then a < c.
+
+     2) useless_type_conversion_p is not symmetric.
+	From a < b does not follow a > b.
+
+     3) Types define the available set of operations applicable to values.
+	A type conversion is useless if the operations for the target type
+	is a subset of the operations for the source type.  For example
+	casts to void* are useless, casts from void* are not (void* can't
+	be dereferenced or offsetted, but copied, hence its set of operations
+	is a strict subset of that of all other data pointer types).  Casts
+	to const T* are useless (can't be written to), casts from const T*
+	to T* are not.  */
+
+bool
+useless_type_conversion_p (tree outer_type, tree inner_type)
 {
   /* Do the following before stripping toplevel qualifiers.  */
   if (POINTER_TYPE_P (inner_type)
@@ -909,6 +930,16 @@ useless_type_conversion_p_1 (tree outer_type, tree inner_type)
   else if (POINTER_TYPE_P (inner_type)
 	   && POINTER_TYPE_P (outer_type))
     {
+      /* If the outer type is (void *) or a pointer to an incomplete
+	 record type, then the conversion is not necessary.  */
+      if (VOID_TYPE_P (TREE_TYPE (outer_type))
+	  || (AGGREGATE_TYPE_P (TREE_TYPE (outer_type))
+	      && TREE_CODE (TREE_TYPE (outer_type)) != ARRAY_TYPE
+	      && (TREE_CODE (TREE_TYPE (outer_type))
+		  == TREE_CODE (TREE_TYPE (inner_type)))
+	      && !COMPLETE_TYPE_P (TREE_TYPE (outer_type))))
+	return true;
+
       /* Don't lose casts between pointers to volatile and non-volatile
 	 qualified types.  Doing so would result in changing the semantics
 	 of later accesses.  For function types the volatile qualifier
@@ -938,8 +969,11 @@ useless_type_conversion_p_1 (tree outer_type, tree inner_type)
       /* Otherwise pointers/references are equivalent if their pointed
 	 to types are effectively the same.  We can strip qualifiers
 	 on pointed-to types for further comparison, which is done in
-	 the callee.  */
-      return useless_type_conversion_p_1 (TREE_TYPE (outer_type),
+	 the callee.  Note we have to use true compatibility here
+	 because addresses are subject to propagation into dereferences
+	 and thus might get the original type exposed which is equivalent
+	 to a reverse conversion.  */
+      return types_compatible_p (TREE_TYPE (outer_type),
 				 TREE_TYPE (inner_type));
     }
 
@@ -1083,48 +1117,6 @@ useless_type_conversion_p_1 (tree outer_type, tree inner_type)
   return false;
 }
 
-/* Return true if the conversion from INNER_TYPE to OUTER_TYPE is a
-   useless type conversion, otherwise return false.
-
-   This function implicitly defines the middle-end type system.  With
-   the notion of 'a < b' meaning that useless_type_conversion_p (a, b)
-   holds and 'a > b' meaning that useless_type_conversion_p (b, a) holds,
-   the following invariants shall be fulfilled:
-
-     1) useless_type_conversion_p is transitive.
-	If a < b and b < c then a < c.
-
-     2) useless_type_conversion_p is not symmetric.
-	From a < b does not follow a > b.
-
-     3) Types define the available set of operations applicable to values.
-	A type conversion is useless if the operations for the target type
-	is a subset of the operations for the source type.  For example
-	casts to void* are useless, casts from void* are not (void* can't
-	be dereferenced or offsetted, but copied, hence its set of operations
-	is a strict subset of that of all other data pointer types).  Casts
-	to const T* are useless (can't be written to), casts from const T*
-	to T* are not.  */
-
-bool
-useless_type_conversion_p (tree outer_type, tree inner_type)
-{
-  /* If the outer type is (void *) or a pointer to an incomplete record type,
-     then the conversion is not necessary.
-     We have to make sure to not apply this while recursing though.  */
-  if (POINTER_TYPE_P (inner_type)
-      && POINTER_TYPE_P (outer_type)
-      && (VOID_TYPE_P (TREE_TYPE (outer_type))
-	  || (AGGREGATE_TYPE_P (TREE_TYPE (outer_type))
-	      && TREE_CODE (TREE_TYPE (outer_type)) != ARRAY_TYPE
-	      && (TREE_CODE (TREE_TYPE (outer_type))
-		  == TREE_CODE (TREE_TYPE (inner_type)))
-	      && !COMPLETE_TYPE_P (TREE_TYPE (outer_type)))))
-    return true;
-
-  return useless_type_conversion_p_1 (outer_type, inner_type);
-}
-
 /* Return true if a conversion from either type of TYPE1 and TYPE2
    to the other is not required.  Otherwise return false.  */