cp-tree.h (BINFO_OVERRIDE_ALONG_VIRTUAL_PATH): New macro.

	* cp-tree.h (BINFO_OVERRIDE_ALONG_VIRTUAL_PATH): New macro.
	* class.c (dfs_find_final_overrider): Set it appropriately.
	(dfs_built_vtt_inits): Check BINFO_OVERRIDE_ALONG_VIRTUAL_PATH to
	avoid unneeded secondary vptrs.

From-SVN: r34549

gcc/cp/ChangeLog

+2000-06-14  Mark Mitchell  <mark@codesourcery.com>
+
+	* cp-tree.h (BINFO_OVERRIDE_ALONG_VIRTUAL_PATH): New macro.
+	* class.c (dfs_find_final_overrider): Set it appropriately.
+	(dfs_built_vtt_inits): Check BINFO_OVERRIDE_ALONG_VIRTUAL_PATH to
+	avoid unneeded secondary vptrs.
+
 2000-06-13  Jakub Jelinek  <jakub@redhat.com>
 
 	* class.c (build_secondary_vtable): Set DECL_USER_ALIGN.

gcc/cp/class.c

@@ -2453,9 +2453,11 @@ dfs_find_final_overrider (binfo, data)
       tree path;
       tree method;
 
+      /* We haven't found an overrider yet.  */
+      method = NULL_TREE;
       /* We've found a path to the declaring base.  Walk down the path
 	 looking for an overrider for FN.  */
-      for (path = reverse_path (binfo); 
+      for (path = reverse_path (binfo);
 	   path; 
 	   path = TREE_CHAIN (path))
 	{
@@ -2474,6 +2476,24 @@ dfs_find_final_overrider (binfo, data)
 	 the base from which it came.  */
       if (path)
 	{
+	  tree base;
+
+	  /* Assume the path is non-virtual.  See if there are any base from
+	     (but not including) the overrider up to and including the
+	     base where the function is defined. */
+	  for (base = TREE_CHAIN (path); base; base = TREE_CHAIN (base))
+	    if (TREE_VIA_VIRTUAL (TREE_VALUE (base)))
+	      {
+		base = ffod->declaring_base;
+		while (BINFO_PRIMARY_MARKED_P (base))
+		  {
+		    BINFO_OVERRIDE_ALONG_VIRTUAL_PATH_P (base) = 1;
+		    base = BINFO_INHERITANCE_CHAIN (base);
+		  }
+		BINFO_OVERRIDE_ALONG_VIRTUAL_PATH_P (base) = 1;
+		break;
+	      }
+
 	  if (ffod->overriding_fn && ffod->overriding_fn != method)
 	    {
 	      /* We've found a different overrider along a different
@@ -6729,10 +6749,19 @@ dfs_build_vtt_inits (binfo, data)
 
   /* If BINFO doesn't have virtual bases, then we have to look to see
      whether or not any virtual functions were overidden along a
-     virtual path between the declaration and T.  */
-  if (!TYPE_USES_VIRTUAL_BASECLASSES (BINFO_TYPE (binfo)))
-    /* FIXME: Implement this.  */
-    ;
+     virtual path.  The point is that given:
+
+       struct V { virtual void f(); int i; };
+       struct C : public V { void f (); };
+
+     when we constrct C we need a secondary vptr for V-in-C because we
+     don't know what the vcall offset for `f' should be.  If `V' ends
+     up in a different place in the complete object, then we'll need a
+     different vcall offset than that present in the normal V-in-C
+     vtable.  */
+  if (!TYPE_USES_VIRTUAL_BASECLASSES (BINFO_TYPE (binfo))
+      && !BINFO_OVERRIDE_ALONG_VIRTUAL_PATH_P (binfo))
+    return NULL_TREE;
 
   /* Record the index where this secondary vptr can be found.  */
   index = TREE_TYPE (l);

gcc/cp/cp-tree.h

@@ -55,11 +55,13 @@ Boston, MA 02111-1307, USA.  */
       BASELINK_P (in TREE_LIST)
       ICS_ELLIPSIS_FLAG (in _CONV)
       STMT_IS_FULL_EXPR_P (in _STMT)
+      BINFO_ACCESS (in BINFO)
    2: IDENTIFIER_OPNAME_P.
       TYPE_POLYMORHPIC_P (in _TYPE)
       ICS_THIS_FLAG (in _CONV)
       STMT_LINENO_FOR_FN_P (in _STMT)
       BINDING_HAS_LEVEL_P (in CPLUS_BINDING)
+      BINFO_OVERRIDE_ALONG_VIRTUAL_PATH_P (in BINFO)
    3: TYPE_USES_VIRTUAL_BASECLASSES (in a class TYPE).
       BINFO_VTABLE_PATH_MARKED.
       BINFO_PUSHDECLS_MARKED.
@@ -76,6 +78,7 @@ Boston, MA 02111-1307, USA.  */
       IDENTIFIER_TYPENAME_P (in IDENTIFIER_NODE)
    5: BINFO_PRIMARY_MARKED_P (in BINFO)
    6: BINFO_VBASE_PRIMARY_P (in BINFO)
+      BINFO_ACCESS (in BINFO)
 
    Usage of TYPE_LANG_FLAG_?:
    0: C_TYPE_FIELDS_READONLY (in RECORD_TYPE or UNION_TYPE).
@@ -1784,6 +1787,10 @@ struct lang_type
    found.  NULL_TREE if there is no secondary vptr in the VTT.  */
 #define BINFO_VPTR_INDEX(NODE) TREE_VEC_ELT ((NODE), 9)
 
+/* Nonzero if this binfo declares a virtual function which is
+   overridden along a virtual path.  */
+#define BINFO_OVERRIDE_ALONG_VIRTUAL_PATH_P(NODE) TREE_LANG_FLAG_2 (NODE)
+
 /* Used by various search routines.  */
 #define IDENTIFIER_MARKED(NODE) TREE_LANG_FLAG_0 (NODE)