tree-flow.h (array_at_struct_end_p): Move declaration ...

2012-04-17  Richard Guenther  <rguenther@suse.de>

	* tree-flow.h (array_at_struct_end_p): Move declaration ...
	* tree.h (array_at_struct_end_p): ... here.
	* tree-ssa-loop-niter.c (array_at_struct_end_p): Move ...
	* expr.c (array_at_struct_end_p): ... here.  Rewrite.

From-SVN: r186527

1 files changed, 37 insertions, 0 deletions

diff --git a/gcc/expr.c b/gcc/expr.c
index 46282d1..479dacf 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -6778,6 +6778,43 @@ array_ref_low_bound (tree exp)
   return build_int_cst (TREE_TYPE (TREE_OPERAND (exp, 1)), 0);
 }
 
+/* Returns true if REF is an array reference to an array at the end of
+   a structure.  If this is the case, the array may be allocated larger
+   than its upper bound implies.  */
+
+bool
+array_at_struct_end_p (tree ref)
+{
+  if (TREE_CODE (ref) != ARRAY_REF
+      && TREE_CODE (ref) != ARRAY_RANGE_REF)
+    return false;
+
+  while (handled_component_p (ref))
+    {
+      /* If the reference chain contains a component reference to a
+         non-union type and there follows another field the reference
+	 is not at the end of a structure.  */
+      if (TREE_CODE (ref) == COMPONENT_REF
+	  && TREE_CODE (TREE_TYPE (TREE_OPERAND (ref, 0))) == RECORD_TYPE)
+	{
+	  tree nextf = DECL_CHAIN (TREE_OPERAND (ref, 1));
+	  while (nextf && TREE_CODE (nextf) != FIELD_DECL)
+	    nextf = DECL_CHAIN (nextf);
+	  if (nextf)
+	    return false;
+	}
+
+      ref = TREE_OPERAND (ref, 0);
+    }
+
+  /* If the reference is based on a declared entity, the size of the array
+     is constrained by its given domain.  */
+  if (DECL_P (ref))
+    return false;
+
+  return true;
+}
+
 /* Return a tree representing the upper bound of the array mentioned in
    EXP, an ARRAY_REF or an ARRAY_RANGE_REF.  */