[PATCH, PR 46053] Devirtualization and thunks revisited

[Martin Jambor <mjambor at suse dot cz>]

Hi,

PR 46053 showed that my previous attempt to incorporate thunks to
devirtualization (fix to PR 45699) was only half-baked and did not
work when we do devirtualization after IPA propagation of type
information (rather obviously, I must admit).

Basically, some thunk or delta information has to be attached to
indirect edges representing polymorphic calls too.  However, I did not
like the idea of having thunks as callees of cgraph edges and,
moreover, there have been concerns that direct calls to thunks might
be unintelligible to some our analyses as well.

So I revisited the whole approach to devirtualization to thunks which
are there to adjust the this offset by a delta and resorted to adding
delta to the parameter directly in the caller.  In order to do this, I
save the delta in the indirect_info of an originally-indirect edge.

Because generating a delta addition statement is impossible when
folding a statement inplace, I rearranged the folding code a bit as
well. 

This patch is to be applied on top of
http://gcc.gnu.org/ml/gcc-patches/2010-10/msg01328.html
(It might apply and work without it but I have not tried it).

Bootstrapped and tested on x86_64-linux without any problems.  OK for
trunk (preferably after the patch referenced above)?

Thanks,

Martin


2010-10-19  Martin Jambor  <mjambor@suse.cz>

	PR tree-optimization/46053
	* cgraph.h (cgraph_indirect_call_info): New field.
	* gimple.h (gimple_fold_obj_type_ref): Declaration removed.
	(gimple_fold_call): Declare.
	(gimple_adjust_this_by_delta): Likewise.
	* cgraph.c (cgraph_make_edge_direct): New parameter delta.  Updated
	all users.
	(cgraph_clone_edge): Create a copy of indirect_info also for direct
	edges.
	* cgraphunit.c (cgraph_redirect_edge_call_stmt_to_callee): Adjust this
	parameters.
	* gimple-fold.c (gimple_fold_obj_type_ref_known_binfo): Renamed to
	gimple_get_virt_mehtod_for_binfo, new parameter delta.  Do not search
	through thunks, check that BINFO_VIRTUALS is not NULL.
	(gimple_adjust_this_by_delta): New function.
	(gimple_fold_obj_type_ref): Removed.
	(gimple_fold_obj_type_ref_call): New function.
	(fold_gimple_call): Renamed to gimple_fold_call, made external.
	Updated users.  Call gimple_fold_obj_type_ref_call instead of
	gimple_fold_obj_type_ref.
	* ipa-cp.c (ipcp_process_devirtualization_opportunities): Process
	thunk deltas.
	(ipcp_discover_new_direct_edges): Likewise.
	* ipa-prop.c (ipa_make_edge_direct_to_target): New parameter delta.
	Updated callers.
	(ipa_write_indirect_edge_info): Stream thunk_delta.
	(ipa_read_indirect_edge_info): Likewise.
	* tree-ssa-ccp.c (ccp_fold_stmt): Use gimple_fold_call instead of
	gimple_fold_obj_type_ref.

	* testsuite/g++.dg/ipa/pr46053.C: New test.

Index: icln/gcc/cgraph.c
===================================================================
--- icln.orig/gcc/cgraph.c
+++ icln/gcc/cgraph.c
@@ -847,7 +847,7 @@ cgraph_set_call_stmt (struct cgraph_edge
 	 indirect call into a direct one.  */
       struct cgraph_node *new_callee = cgraph_node (decl);
 
-      cgraph_make_edge_direct (e, new_callee);
+      cgraph_make_edge_direct (e, new_callee, NULL);
     }
 
   push_cfun (DECL_STRUCT_FUNCTION (e->caller->decl));
@@ -1184,12 +1184,15 @@ cgraph_redirect_edge_callee (struct cgra
 }
 
 /* Make an indirect EDGE with an unknown callee an ordinary edge leading to
-   CALLEE.  */
+   CALLEE.  DELTA, if non-NULL, is an integer constant that is to be added to
+   the this pointer (first parameter).  */
 
 void
-cgraph_make_edge_direct (struct cgraph_edge *edge, struct cgraph_node *callee)
+cgraph_make_edge_direct (struct cgraph_edge *edge, struct cgraph_node *callee,
+			 tree delta)
 {
   edge->indirect_unknown_callee = 0;
+  edge->indirect_info->thunk_delta = delta;
 
   /* Get the edge out of the indirect edge list. */
   if (edge->prev_callee)
@@ -2101,8 +2104,16 @@ cgraph_clone_edge (struct cgraph_edge *e
 	}
     }
   else
-    new_edge = cgraph_create_edge (n, e->callee, call_stmt, count, freq,
-				   e->loop_nest + loop_nest);
+    {
+      new_edge = cgraph_create_edge (n, e->callee, call_stmt, count, freq,
+				     e->loop_nest + loop_nest);
+      if (e->indirect_info)
+	{
+	  new_edge->indirect_info
+	    = ggc_alloc_cleared_cgraph_indirect_call_info ();
+	  *new_edge->indirect_info = *e->indirect_info;
+	}
+    }
 
   new_edge->inline_failed = e->inline_failed;
   new_edge->indirect_inlining_edge = e->indirect_inlining_edge;
Index: icln/gcc/cgraph.h
===================================================================
--- icln.orig/gcc/cgraph.h
+++ icln/gcc/cgraph.h
@@ -398,6 +398,9 @@ struct GTY(()) cgraph_indirect_call_info
   HOST_WIDE_INT otr_token;
   /* Type of the object from OBJ_TYPE_REF_OBJECT. */
   tree otr_type;
+  /* Delta by which must be added to this parameter.  For polymorphic calls
+     only.  */
+  tree thunk_delta;
   /* Index of the parameter that is called.  */
   int param_index;
   /* ECF flags determined from the caller.  */
@@ -585,7 +588,7 @@ struct cgraph_node * cgraph_clone_node (
 					int, bool, VEC(cgraph_edge_p,heap) *);
 
 void cgraph_redirect_edge_callee (struct cgraph_edge *, struct cgraph_node *);
-void cgraph_make_edge_direct (struct cgraph_edge *, struct cgraph_node *);
+void cgraph_make_edge_direct (struct cgraph_edge *, struct cgraph_node *, tree);
 
 struct cgraph_asm_node *cgraph_add_asm_node (tree);
 
Index: icln/gcc/cgraphunit.c
===================================================================
--- icln.orig/gcc/cgraphunit.c
+++ icln/gcc/cgraphunit.c
@@ -2115,6 +2115,8 @@ cgraph_redirect_edge_call_stmt_to_callee
 {
   tree decl = gimple_call_fndecl (e->call_stmt);
   gimple new_stmt;
+  gimple_stmt_iterator gsi;
+  bool gsi_computed = false;
 #ifdef ENABLE_CHECKING
   struct cgraph_node *node;
 #endif
@@ -2147,9 +2149,24 @@ cgraph_redirect_edge_call_stmt_to_callee
 	}
     }
 
+  if (e->indirect_info && e->indirect_info->thunk_delta
+      && integer_nonzerop (e->indirect_info->thunk_delta))
+    {
+      if (cgraph_dump_file)
+	{
+	  fprintf (cgraph_dump_file, "          Thunk delta is ");
+	  print_generic_expr (cgraph_dump_file,
+			      e->indirect_info->thunk_delta, 0);
+	  fprintf (cgraph_dump_file, "\n");
+	}
+      gsi = gsi_for_stmt (e->call_stmt);
+      gsi_computed = true;
+      gimple_adjust_this_by_delta (&gsi, e->indirect_info->thunk_delta);
+      e->indirect_info->thunk_delta = NULL_TREE;
+    }
+
   if (e->callee->clone.combined_args_to_skip)
     {
-      gimple_stmt_iterator gsi;
       int lp_nr;
 
       new_stmt
@@ -2161,7 +2178,8 @@ cgraph_redirect_edge_call_stmt_to_callee
 	  && TREE_CODE (gimple_vdef (new_stmt)) == SSA_NAME)
 	SSA_NAME_DEF_STMT (gimple_vdef (new_stmt)) = new_stmt;
 
-      gsi = gsi_for_stmt (e->call_stmt);
+      if (!gsi_computed)
+	gsi = gsi_for_stmt (e->call_stmt);
       gsi_replace (&gsi, new_stmt, false);
       /* We need to defer cleaning EH info on the new statement to
          fixup-cfg.  We may not have dominator information at this point
Index: icln/gcc/gimple-fold.c
===================================================================
--- icln.orig/gcc/gimple-fold.c
+++ icln/gcc/gimple-fold.c
@@ -1459,14 +1459,20 @@ gimple_get_relevant_ref_binfo (tree ref,
 
 /* Fold a OBJ_TYPE_REF expression to the address of a function. TOKEN is
    integer form of OBJ_TYPE_REF_TOKEN of the reference expression.  KNOWN_BINFO
-   carries the binfo describing the true type of OBJ_TYPE_REF_OBJECT(REF).  */
+   carries the binfo describing the true type of OBJ_TYPE_REF_OBJECT(REF).
+   Delta, if non-NULL, is an integer contant that should be added to this
+   pointer (first parameter). */
 
 tree
-gimple_fold_obj_type_ref_known_binfo (HOST_WIDE_INT token, tree known_binfo)
+gimple_get_virt_mehtod_for_binfo (HOST_WIDE_INT token, tree known_binfo,
+				  tree *delta)
 {
   HOST_WIDE_INT i;
-  tree v, fndecl, delta;
+  tree v, fndecl;
 
+  /* If there is no virtual methods leave the OBJ_TYPE_REF alone.  */
+  if (!BINFO_VIRTUALS (known_binfo))
+    return NULL_TREE;
   gcc_assert (BINFO_NEW_VTABLE_MARKED (known_binfo));
   v = BINFO_VIRTUALS (known_binfo);
   i = 0;
@@ -1478,62 +1484,77 @@ gimple_fold_obj_type_ref_known_binfo (HO
     }
 
   fndecl = TREE_VALUE (v);
-  delta = TREE_PURPOSE (v);
-  gcc_assert (host_integerp (delta, 0));
-
-  if (integer_nonzerop (delta))
-    {
-      struct cgraph_node *node = cgraph_get_node (fndecl);
-      HOST_WIDE_INT off = tree_low_cst (delta, 0);
-
-      if (!node)
-        return NULL;
-      for (node = node->same_body; node; node = node->next)
-        if (node->thunk.thunk_p && off == node->thunk.fixed_offset)
-          break;
-      if (node)
-        fndecl = node->decl;
-      else
-        return NULL;
-     }
+  *delta = TREE_PURPOSE (v);
+  gcc_checking_assert (host_integerp (*delta, 0));
 
   /* When cgraph node is missing and function is not public, we cannot
      devirtualize.  This can happen in WHOPR when the actual method
      ends up in other partition, because we found devirtualization
      possibility too late.  */
-  if (!can_refer_decl_in_current_unit_p (fndecl))
-    return NULL;
-  return build_fold_addr_expr (fndecl);
+  if (!can_refer_decl_in_current_unit_p (TREE_VALUE (v)))
+    return NULL_TREE;
+  return fndecl;
 }
 
+/* Generate code adjusting the first parameter of a call statement determined
+   by GSI by DELTA.  */
 
-/* Fold a OBJ_TYPE_REF expression to the address of a function.  If KNOWN_TYPE
-   is not NULL_TREE, it is the true type of the outmost encapsulating object if
-   that comes from a pointer SSA_NAME.  If the true outmost encapsulating type
-   can be determined from a declaration OBJ_TYPE_REF_OBJECT(REF), it is used
-   regardless of KNOWN_TYPE (which thus can be NULL_TREE).  */
+void
+gimple_adjust_this_by_delta (gimple_stmt_iterator *gsi, tree delta)
+{
+  gimple call_stmt = gsi_stmt (*gsi);
+  tree parm, tmp;
+  gimple new_stmt;
+
+  delta = fold_convert (sizetype, delta);
+  gcc_assert (gimple_call_num_args (call_stmt) >= 1);
+  parm = gimple_call_arg (call_stmt, 0);
+  gcc_assert (POINTER_TYPE_P (TREE_TYPE (parm)));
+  tmp = create_tmp_var (TREE_TYPE (parm), NULL);
+  add_referenced_var (tmp);
+
+  tmp = make_ssa_name (tmp, NULL);
+  new_stmt = gimple_build_assign_with_ops (POINTER_PLUS_EXPR, tmp, parm, delta);
+  SSA_NAME_DEF_STMT (tmp) = new_stmt;
+  gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
+  gimple_call_set_arg (call_stmt, 0, tmp);
+}
 
-tree
-gimple_fold_obj_type_ref (tree ref, tree known_type)
+/* Fold a call statement to OBJ_TYPE_REF to a direct call, if possible.  GSI
+   determines the statement, generating new statements is allowed only if
+   INPLACE is false.  Return true iff the statement was changed.  */
+
+static bool
+gimple_fold_obj_type_ref_call (gimple_stmt_iterator *gsi, bool inplace)
 {
+  gimple stmt = gsi_stmt (*gsi);
+  tree ref = gimple_call_fn (stmt);
   tree obj = OBJ_TYPE_REF_OBJECT (ref);
-  tree known_binfo = known_type ? TYPE_BINFO (known_type) : NULL_TREE;
-  tree binfo;
+  tree binfo, fndecl, delta;
+  HOST_WIDE_INT token;
 
   if (TREE_CODE (obj) == ADDR_EXPR)
     obj = TREE_OPERAND (obj, 0);
+  else
+    return false;
 
-  binfo = gimple_get_relevant_ref_binfo (obj, known_binfo);
-  if (binfo)
+  binfo = gimple_get_relevant_ref_binfo (obj, NULL_TREE);
+  if (!binfo)
+    return false;
+  token = tree_low_cst (OBJ_TYPE_REF_TOKEN (ref), 1);
+  fndecl = gimple_get_virt_mehtod_for_binfo (token, binfo, &delta);
+  if (!fndecl)
+    return false;
+
+  if (integer_nonzerop (delta))
     {
-      HOST_WIDE_INT token = tree_low_cst (OBJ_TYPE_REF_TOKEN (ref), 1);
-      /* If there is no virtual methods leave the OBJ_TYPE_REF alone.  */
-      if (!BINFO_VIRTUALS (binfo))
-	return NULL_TREE;
-      return gimple_fold_obj_type_ref_known_binfo (token, binfo);
+      if (inplace)
+        return false;
+      gimple_adjust_this_by_delta (gsi, delta);
     }
-  else
-    return NULL_TREE;
+
+  gimple_call_set_fndecl (stmt, fndecl);
+  return true;
 }
 
 /* Attempt to fold a call statement referenced by the statement iterator GSI.
@@ -1541,8 +1562,8 @@ gimple_fold_obj_type_ref (tree ref, tree
    simplifies to a constant value. Return true if any changes were made.
    It is assumed that the operands have been previously folded.  */
 
-static bool
-fold_gimple_call (gimple_stmt_iterator *gsi, bool inplace)
+bool
+gimple_fold_call (gimple_stmt_iterator *gsi, bool inplace)
 {
   gimple stmt = gsi_stmt (*gsi);
 
@@ -1568,18 +1589,8 @@ fold_gimple_call (gimple_stmt_iterator *
          copying EH region info to the new node.  Easier to just do it
          here where we can just smash the call operand.  */
       callee = gimple_call_fn (stmt);
-      if (TREE_CODE (callee) == OBJ_TYPE_REF
-          && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee)) == ADDR_EXPR)
-        {
-          tree t;
-
-          t = gimple_fold_obj_type_ref (callee, NULL_TREE);
-          if (t)
-            {
-              gimple_call_set_fn (stmt, t);
-              return true;
-            }
-        }
+      if (TREE_CODE (callee) == OBJ_TYPE_REF)
+	return gimple_fold_obj_type_ref_call (gsi, inplace);
     }
 
   return false;
@@ -1633,7 +1644,7 @@ fold_stmt_1 (gimple_stmt_iterator *gsi,
 		changed = true;
 	      }
 	  }
-      changed |= fold_gimple_call (gsi, inplace);
+      changed |= gimple_fold_call (gsi, inplace);
       break;
 
     case GIMPLE_ASM:
Index: icln/gcc/gimple.h
===================================================================
--- icln.orig/gcc/gimple.h
+++ icln/gcc/gimple.h
@@ -894,10 +894,10 @@ unsigned get_gimple_rhs_num_ops (enum tr
 #define gimple_alloc(c, n) gimple_alloc_stat (c, n MEM_STAT_INFO)
 gimple gimple_alloc_stat (enum gimple_code, unsigned MEM_STAT_DECL);
 const char *gimple_decl_printable_name (tree, int);
-tree gimple_fold_obj_type_ref (tree, tree);
+bool gimple_fold_call (gimple_stmt_iterator *gsi, bool inplace);
 tree gimple_get_relevant_ref_binfo (tree ref, tree known_binfo);
-tree gimple_fold_obj_type_ref_known_binfo (HOST_WIDE_INT, tree);
-
+tree gimple_get_virt_mehtod_for_binfo (HOST_WIDE_INT, tree, tree *);
+void gimple_adjust_this_by_delta (gimple_stmt_iterator *, tree);
 /* Returns true iff T is a valid GIMPLE statement.  */
 extern bool is_gimple_stmt (tree);
 
Index: icln/gcc/ipa-cp.c
===================================================================
--- icln.orig/gcc/ipa-cp.c
+++ icln/gcc/ipa-cp.c
@@ -1205,7 +1205,7 @@ ipcp_process_devirtualization_opportunit
     {
       int param_index, types_count, j;
       HOST_WIDE_INT token;
-      tree target;
+      tree target, delta;
 
       next_ie = ie->next_callee;
       if (!ie->indirect_info->polymorphic)
@@ -1222,7 +1222,8 @@ ipcp_process_devirtualization_opportunit
       for (j = 0; j < types_count; j++)
 	{
 	  tree binfo = VEC_index (tree, info->params[param_index].types, j);
-	  tree t = gimple_fold_obj_type_ref_known_binfo (token, binfo);
+	  tree d;
+	  tree t = gimple_get_virt_mehtod_for_binfo (token, binfo, &d);
 
 	  if (!t)
 	    {
@@ -1230,8 +1231,11 @@ ipcp_process_devirtualization_opportunit
 	      break;
 	    }
 	  else if (!target)
-	    target = t;
-	  else if (target != t)
+	    {
+	      target = t;
+	      delta = d;
+	    }
+	  else if (target != t || !tree_int_cst_equal (delta, d))
 	    {
 	      target = NULL_TREE;
 	      break;
@@ -1239,7 +1243,7 @@ ipcp_process_devirtualization_opportunit
 	}
 
       if (target)
-	ipa_make_edge_direct_to_target (ie, target);
+	ipa_make_edge_direct_to_target (ie, target, delta);
     }
 }
 
@@ -1279,6 +1283,7 @@ ipcp_discover_new_direct_edges (struct c
   for (ie = node->indirect_calls; ie; ie = next_ie)
     {
       struct cgraph_indirect_call_info *ici = ie->indirect_info;
+      tree target, delta = NULL_TREE;
 
       next_ie = ie->next_callee;
       if (ici->param_index != index)
@@ -1298,12 +1303,14 @@ ipcp_discover_new_direct_edges (struct c
 	    continue;
 	  gcc_assert (ie->indirect_info->anc_offset == 0);
 	  token = ie->indirect_info->otr_token;
-	  cst = gimple_fold_obj_type_ref_known_binfo (token, binfo);
-	  if (!cst)
+	  target = gimple_get_virt_mehtod_for_binfo (token, binfo, &delta);
+	  if (!target)
 	    continue;
 	}
+      else
+	target = cst;
 
-      ipa_make_edge_direct_to_target (ie, cst);
+      ipa_make_edge_direct_to_target (ie, target, delta);
     }
 }
 
Index: icln/gcc/ipa-prop.c
===================================================================
--- icln.orig/gcc/ipa-prop.c
+++ icln/gcc/ipa-prop.c
@@ -1432,35 +1432,43 @@ update_jump_functions_after_inlining (st
 }
 
 /* If TARGET is an addr_expr of a function declaration, make it the destination
-   of an indirect edge IE and return the edge.  Otherwise, return NULL.  */
+   of an indirect edge IE and return the edge.  Otherwise, return NULL.  Delta,
+   if non-NULL, is an integer constant that must be added to this pointer
+   (first parameter).  */
 
 struct cgraph_edge *
-ipa_make_edge_direct_to_target (struct cgraph_edge *ie, tree target)
+ipa_make_edge_direct_to_target (struct cgraph_edge *ie, tree target, tree delta)
 {
   struct cgraph_node *callee;
 
-  if (TREE_CODE (target) != ADDR_EXPR)
-    return NULL;
-  target = TREE_OPERAND (target, 0);
+  if (TREE_CODE (target) == ADDR_EXPR)
+    target = TREE_OPERAND (target, 0);
   if (TREE_CODE (target) != FUNCTION_DECL)
     return NULL;
   callee = cgraph_node (target);
   if (!callee)
     return NULL;
   ipa_check_create_node_params ();
-  cgraph_make_edge_direct (ie, callee);
+
+  cgraph_make_edge_direct (ie, callee, delta);
   if (dump_file)
     {
       fprintf (dump_file, "ipa-prop: Discovered %s call to a known target "
-	       "(%s/%i -> %s/%i) for stmt ",
+	       "(%s/%i -> %s/%i), for stmt ",
 	       ie->indirect_info->polymorphic ? "a virtual" : "an indirect",
 	       cgraph_node_name (ie->caller), ie->caller->uid,
 	       cgraph_node_name (ie->callee), ie->callee->uid);
-
       if (ie->call_stmt)
 	print_gimple_stmt (dump_file, ie->call_stmt, 2, TDF_SLIM);
       else
 	fprintf (dump_file, "with uid %i\n", ie->lto_stmt_uid);
+
+      if (delta)
+	{
+	  fprintf (dump_file, "          Thunk delta is ");
+	  print_generic_expr (dump_file, delta, 0);
+	  fprintf (dump_file, "\n");
+	}
     }
 
   if (ipa_get_cs_argument_count (IPA_EDGE_REF (ie))
@@ -1488,7 +1496,7 @@ try_make_edge_direct_simple_call (struct
   else
     return NULL;
 
-  return ipa_make_edge_direct_to_target (ie, target);
+  return ipa_make_edge_direct_to_target (ie, target, NULL_TREE);
 }
 
 /* Try to find a destination for indirect edge IE that corresponds to a
@@ -1500,7 +1508,7 @@ static struct cgraph_edge *
 try_make_edge_direct_virtual_call (struct cgraph_edge *ie,
 				   struct ipa_jump_func *jfunc)
 {
-  tree binfo, type, target;
+  tree binfo, type, target, delta;
   HOST_WIDE_INT token;
 
   if (jfunc->type == IPA_JF_KNOWN_TYPE)
@@ -1524,12 +1532,12 @@ try_make_edge_direct_virtual_call (struc
   type = ie->indirect_info->otr_type;
   binfo = get_binfo_at_offset (binfo, ie->indirect_info->anc_offset, type);
   if (binfo)
-    target = gimple_fold_obj_type_ref_known_binfo (token, binfo);
+    target = gimple_get_virt_mehtod_for_binfo (token, binfo, &delta);
   else
     return NULL;
 
   if (target)
-    return ipa_make_edge_direct_to_target (ie, target);
+    return ipa_make_edge_direct_to_target (ie, target, delta);
   else
     return NULL;
 }
@@ -2520,6 +2528,7 @@ ipa_write_indirect_edge_info (struct out
     {
       lto_output_sleb128_stream (ob->main_stream, ii->otr_token);
       lto_output_tree (ob, ii->otr_type, true);
+      lto_output_tree (ob, ii->thunk_delta, true);
     }
 }
 
@@ -2542,6 +2551,7 @@ ipa_read_indirect_edge_info (struct lto_
     {
       ii->otr_token = (HOST_WIDE_INT) lto_input_sleb128 (ib);
       ii->otr_type = lto_input_tree (ib, data_in);
+      ii->thunk_delta = lto_input_tree (ib, data_in);
     }
 }
 
Index: icln/gcc/ipa-prop.h
===================================================================
--- icln.orig/gcc/ipa-prop.h
+++ icln/gcc/ipa-prop.h
@@ -430,7 +430,8 @@ bool ipa_propagate_indirect_call_infos (
 					VEC (cgraph_edge_p, heap) **new_edges);
 
 /* Indirect edge and binfo processing.  */
-struct cgraph_edge *ipa_make_edge_direct_to_target (struct cgraph_edge *, tree);
+struct cgraph_edge *ipa_make_edge_direct_to_target (struct cgraph_edge *, tree,
+						    tree);
 
 
 /* Debugging interface.  */
Index: icln/gcc/tree-ssa-ccp.c
===================================================================
--- icln.orig/gcc/tree-ssa-ccp.c
+++ icln/gcc/tree-ssa-ccp.c
@@ -2314,16 +2314,8 @@ ccp_fold_stmt (gimple_stmt_iterator *gsi
 	  {
 	    tree expr = OBJ_TYPE_REF_EXPR (callee);
 	    OBJ_TYPE_REF_EXPR (callee) = valueize_op (expr);
-	    if (TREE_CODE (OBJ_TYPE_REF_EXPR (callee)) == ADDR_EXPR)
-	      {
-		tree t;
-		t = gimple_fold_obj_type_ref (callee, NULL_TREE);
-		if (t)
-		  {
-		    gimple_call_set_fn (stmt, t);
-		    changed = true;
-		  }
-	      }
+	    if (gimple_fold_call (gsi, false))
+	      changed = true;
 	    OBJ_TYPE_REF_EXPR (callee) = expr;
 	  }
 
Index: icln/gcc/testsuite/g++.dg/ipa/pr46053.C
===================================================================
--- /dev/null
+++ icln/gcc/testsuite/g++.dg/ipa/pr46053.C
@@ -0,0 +1,41 @@
+/* { dg-do run } */
+/* { dg-options "-O -fipa-cp -fno-early-inlining"  } */
+
+extern "C" void abort ();
+
+struct A
+{
+  virtual void foo () = 0;
+};
+
+struct B : A
+{
+  virtual void foo () = 0;
+};
+
+struct C : A
+{
+};
+
+struct D : C, B
+{
+  int i;
+  D () : i(0xaaaa) {}
+  virtual void foo ()
+  {
+    if (i != 0xaaaa)
+      abort();
+  }
+};
+
+static inline void bar (B &b)
+{
+  b.foo ();
+}
+
+int main()
+{
+  D d;
+  bar (d);
+  return 0;
+}