1 files changed, 56 insertions, 0 deletions
diff --git a/gcc/tree.c b/gcc/tree.c
index 8c0ed4e..f00f82e 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -10779,4 +10779,60 @@ lhd_gcc_personality (void)
   return gcc_eh_personality_decl;
 }
 
+/* Try to find a base info of BINFO that would have its field decl at offset
+   OFFSET within the BINFO type and which is of EXPECTED_TYPE.  If it can be
+   found, return, otherwise return NULL_TREE.  */
+
+tree
+get_binfo_at_offset (tree binfo, HOST_WIDE_INT offset, tree expected_type)
+{
+  tree type;
+
+  if (offset == 0)
+    return binfo;
+
+  type = TREE_TYPE (binfo);
+  while (offset > 0)
+    {
+      tree base_binfo, found_binfo;
+      HOST_WIDE_INT pos, size;
+      tree fld;
+      int i;
+
+      if (TREE_CODE (type) != RECORD_TYPE)
+	return NULL_TREE;
+
+      for (fld = TYPE_FIELDS (type); fld; fld = TREE_CHAIN (fld))
+	{
+	  if (TREE_CODE (fld) != FIELD_DECL)
+	    continue;
+
+	  pos = int_bit_position (fld);
+	  size = tree_low_cst (DECL_SIZE (fld), 1);
+	  if (pos <= offset && (pos + size) > offset)
+	    break;
+	}
+      if (!fld)
+	return NULL_TREE;
+
+      found_binfo = NULL_TREE;
+      for (i = 0; BINFO_BASE_ITERATE (binfo, i, base_binfo); i++)
+	if (TREE_TYPE (base_binfo) == TREE_TYPE (fld))
+	  {
+	    found_binfo = base_binfo;
+	    break;
+	  }
+
+      if (!found_binfo)
+	return NULL_TREE;
+
+      type = TREE_TYPE (fld);
+      binfo = found_binfo;
+      offset -= pos;
+    }
+  if (type != expected_type)
+    return NULL_TREE;
+  return binfo;
+}
+
 #include "gt-tree.h"