re PR tree-optimization/21839 (ICE for missing V_DEFS caused by salias with empty structures)

2005-06-01  Daniel Berlin  <dberlin@dberlin.org>

	Fix PR tree-optimization/21839

	* gimplify.c (zero_sized_field_decl): New function.
	(gimplify_init_ctor_eval): Use it.

From-SVN: r100477

gcc/ChangeLog

+2005-06-01  Daniel Berlin  <dberlin@dberlin.org>
+
+	Fix PR tree-optimization/21839
+
+	* gimplify.c (zero_sized_field_decl): New function.
+	(gimplify_init_ctor_eval): Use it.
+
 2005-06-01  Josh Conner <jconner@apple.com>
 
 	PR 21478
@@ -199,7 +206,6 @@
 	
 	* Makefile.in: Update dependencies.
 	
-
 2005-06-01  Danny Smith  <dannysmith@users.sourceforge.net>
 
 	* config/i386/cygming.h (NO_PROFILE_COUNTERS): Define.

gcc/gimplify.c

@@ -2501,6 +2501,17 @@ gimplify_init_ctor_eval_range (tree object, tree lower, tree upper,
 			    pre_p);
 }
 
+/* Return true if FDECL is accessing a field that is zero sized.  */
+   
+static bool
+zero_sized_field_decl (tree fdecl)
+{
+  if (TREE_CODE (fdecl) == FIELD_DECL && DECL_SIZE (fdecl) 
+      && integer_zerop (DECL_SIZE (fdecl)))
+    return true;
+  return false;
+}
+
 /* A subroutine of gimplify_init_constructor.  Generate individual
    MODIFY_EXPRs for a CONSTRUCTOR.  OBJECT is the LHS against which the
    assignments should happen.  LIST is the CONSTRUCTOR_ELTS of the
@@ -2533,6 +2544,9 @@ gimplify_init_ctor_eval (tree object, tree list, tree *pre_p, bool cleared)
 	 so we don't have to figure out what's missing ourselves.  */
       gcc_assert (purpose);
 
+      if (zero_sized_field_decl (purpose))
+	continue;
+
       /* If we have a RANGE_EXPR, we have to build a loop to assign the
 	 whole range.  */
       if (TREE_CODE (purpose) == RANGE_EXPR)

gcc/testsuite/gcc.c-torture/compile/pr21839.c

+ typedef struct { } spinlock_t;
+typedef struct {
+ unsigned sequence;
+ spinlock_t lock;
+} seqlock_t;
+void ext3_new_inode(seqlock_t *rsv_seqlock)
+{
+ *rsv_seqlock = (seqlock_t) { 0, (spinlock_t) { } };
+
+}
+
+