diff --git a/gcc/ipa-modref-tree.c b/gcc/ipa-modref-tree.c
index 70ec71c3808..6fc2b7298f4 100644
--- a/gcc/ipa-modref-tree.c
+++ b/gcc/ipa-modref-tree.c
@@ -25,6 +25,8 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree.h"
 #include "ipa-modref-tree.h"
 #include "selftest.h"
+#include "tree-ssa-alias.h"
+#include "gimple.h"
 
 /* Return true if both accesses are the same.  */
 bool
@@ -603,6 +605,39 @@ modref_access_node::dump (FILE *out)
   fprintf (out, "\n");
 }
 
+/* Return tree corresponding to parameter of the range in STMT.  */
+tree
+modref_access_node::get_call_arg (const gcall *stmt) const
+{
+  if (parm_index == MODREF_UNKNOWN_PARM)
+    return NULL;
+  if (parm_index == MODREF_STATIC_CHAIN_PARM)
+    return gimple_call_chain (stmt);
+  /* MODREF_RETSLOT_PARM should not happen in access trees since the store
+     is seen explicitly in the caller.  */
+  gcc_checking_assert (parm_index >= 0);
+  if (parm_index >= (int)gimple_call_num_args (stmt))
+    return NULL;
+  return gimple_call_arg (stmt, parm_index);
+}
+
+/* Return tree corresponding to parameter of the range in STMT.  */
+bool
+modref_access_node::get_ao_ref (const gcall *stmt, ao_ref *ref) const
+{
+  tree arg;
+
+  if (!parm_offset_known || !(arg = get_call_arg (stmt)))
+    return false;
+  poly_offset_int off = (poly_offset_int)offset
+	+ ((poly_offset_int)parm_offset << LOG2_BITS_PER_UNIT);
+  poly_int64 off2;
+  if (!off.to_shwi (&off2))
+    return false;
+  ao_ref_init_from_ptr_and_range (ref, arg, true, off2, size, max_size);
+  return true;
+}
+
 #if CHECKING_P
 
 namespace selftest {
diff --git a/gcc/ipa-modref-tree.h b/gcc/ipa-modref-tree.h
index 1fafd59debe..2fcabe480bd 100644
--- a/gcc/ipa-modref-tree.h
+++ b/gcc/ipa-modref-tree.h
@@ -77,7 +77,7 @@ struct GTY(()) modref_access_node
      This has to be limited in order to keep dataflow finite.  */
   unsigned char adjustments;
 
-  /* Return true if access node holds no useful info.  */
+  /* Return true if access node holds some useful info.  */
   bool useful_p () const
     {
       return parm_index != MODREF_UNKNOWN_PARM;
@@ -88,10 +88,13 @@ struct GTY(()) modref_access_node
   bool operator == (modref_access_node &a) const;
   /* Return true if range info is useful.  */
   bool range_info_useful_p () const;
+  /* Return tree corresponding to parameter of the range in STMT.  */
+  tree get_call_arg (const gcall *stmt) const;
+  /* Build ao_ref corresponding to the access and return true if succesful.  */
+  bool get_ao_ref (const gcall *stmt, class ao_ref *ref) const;
   /* Insert A into vector ACCESSES.  Limit size of vector to MAX_ACCESSES and
      if RECORD_ADJUSTMENT is true keep track of adjustment counts.
-     Return 0 if nothing changed, 1 is insertion suceeded and -1 if
-     failed.  */
+     Return 0 if nothing changed, 1 is insertion suceeded and -1 if failed.  */
   static int insert (vec <modref_access_node, va_gc> *&accesses,
 		     modref_access_node a, size_t max_accesses,
 		     bool record_adjustments);
diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index 2965902912f..ba055730558 100644
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -2535,13 +2535,10 @@ refs_output_dependent_p (tree store1, tree store2)
    IF TBAA_P is true, use TBAA oracle.  */
 
 static bool
-modref_may_conflict (const gimple *stmt,
+modref_may_conflict (const gcall *stmt,
 		     modref_tree <alias_set_type> *tt, ao_ref *ref, bool tbaa_p)
 {
   alias_set_type base_set, ref_set;
-  modref_base_node <alias_set_type> *base_node;
-  modref_ref_node <alias_set_type> *ref_node;
-  size_t i, j, k;
 
   if (tt->every_base)
     return true;
@@ -2554,7 +2551,7 @@ modref_may_conflict (const gimple *stmt,
   ref_set = ao_ref_alias_set (ref);
 
   int num_tests = 0, max_tests = param_modref_max_tests;
-  FOR_EACH_VEC_SAFE_ELT (tt->bases, i, base_node)
+  for (auto base_node : tt->bases)
     {
       if (tbaa_p && flag_strict_aliasing)
 	{
@@ -2569,7 +2566,7 @@ modref_may_conflict (const gimple *stmt,
       if (base_node->every_ref)
 	return true;
 
-      FOR_EACH_VEC_SAFE_ELT (base_node->refs, j, ref_node)
+      for (auto ref_node : base_node->refs)
 	{
 	  /* Do not repeat same test as before.  */
 	  if ((ref_set != base_set || base_node->base != ref_node->ref)
@@ -2583,66 +2580,43 @@ modref_may_conflict (const gimple *stmt,
 	      num_tests++;
 	    }
 
-	  /* TBAA checks did not disambiguate,  try to use base pointer, for
-	     that we however need to have ref->ref or ref->base.  */
-	  if (ref_node->every_access || (!ref->ref && !ref->base))
+	  if (ref_node->every_access)
 	    return true;
 
-	  modref_access_node *access_node;
-	  FOR_EACH_VEC_SAFE_ELT (ref_node->accesses, k, access_node)
+	  /* TBAA checks did not disambiguate, try individual accesses.  */
+	  for (auto access_node : ref_node->accesses)
 	    {
 	      if (num_tests >= max_tests)
 		return true;
 
-	      if (access_node->parm_index == MODREF_UNKNOWN_PARM
-		  || access_node->parm_index
-		     >= (int)gimple_call_num_args (stmt))
+	      tree arg = access_node.get_call_arg (stmt);
+	      if (!arg)
 		return true;
 
 	      alias_stats.modref_baseptr_tests++;
-	      tree arg;
-
-	      if (access_node->parm_index == MODREF_STATIC_CHAIN_PARM)
-		arg = gimple_call_chain (stmt);
-	      else
-		arg = gimple_call_arg (stmt, access_node->parm_index);
 
 	      if (integer_zerop (arg) && flag_delete_null_pointer_checks)
 		continue;
 
+	      /* PTA oracle will be unhapy of arg is not an pointer.  */
 	      if (!POINTER_TYPE_P (TREE_TYPE (arg)))
 		return true;
 
-	      /* ao_ref_init_from_ptr_and_range assumes that memory access
-		 starts by the pointed to location.  If we did not track the
-		 offset it is possible that it starts before the actual
-		 pointer.  */
-	      if (!access_node->parm_offset_known)
-		{
-		  if (ptr_deref_may_alias_ref_p_1 (arg, ref))
-		    return true;
-		}
-	      else
+	      /* If we don't have base pointer, give up.  */
+ 	      if (!ref->ref && !ref->base)
+		continue;
+
+	      ao_ref ref2;
+	      if (access_node.get_ao_ref (stmt, &ref2))
 		{
-		  ao_ref ref2;
-		  poly_offset_int off = (poly_offset_int)access_node->offset
-			+ ((poly_offset_int)access_node->parm_offset
-			   << LOG2_BITS_PER_UNIT);
-		  poly_int64 off2;
-		  if (off.to_shwi (&off2))
-		    {
-		      ao_ref_init_from_ptr_and_range
-			     (&ref2, arg, true, off2,
-			      access_node->size,
-			      access_node->max_size);
-		      ref2.ref_alias_set = ref_set;
-		      ref2.base_alias_set = base_set;
-		      if (refs_may_alias_p_1 (&ref2, ref, tbaa_p))
-			return true;
-		    }
-		  else if (ptr_deref_may_alias_ref_p_1 (arg, ref))
+		  ref2.ref_alias_set = ref_node->ref;
+		  ref2.base_alias_set = base_node->base;
+		  if (refs_may_alias_p_1 (&ref2, ref, tbaa_p))
 		    return true;
 		}
+	      else if (ptr_deref_may_alias_ref_p_1 (arg, ref))
+		return true;
+
 	      num_tests++;
 	    }
 	}
diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c
index 0e8c4ed1435..ce0083a6dab 100644
--- a/gcc/tree-ssa-dse.c
+++ b/gcc/tree-ssa-dse.c
@@ -1079,35 +1079,25 @@ dse_optimize_call (gimple_stmt_iterator *gsi, sbitmap live_bytes)
   if (!summary || !summary->try_dse)
     return false;
 
-  modref_base_node <alias_set_type> *base_node;
-  modref_ref_node <alias_set_type> *ref_node;
-  modref_access_node *access_node;
-  size_t i, j, k;
   bool by_clobber_p = false;
 
   /* Walk all memory writes and verify that they are dead.  */
-  FOR_EACH_VEC_SAFE_ELT (summary->stores->bases, i, base_node)
-    FOR_EACH_VEC_SAFE_ELT (base_node->refs, j, ref_node)
-      FOR_EACH_VEC_SAFE_ELT (ref_node->accesses, k, access_node)
+  for (auto base_node : summary->stores->bases)
+    for (auto ref_node : base_node->refs)
+      for (auto access_node : ref_node->accesses)
 	{
-	  gcc_checking_assert (access_node->parm_offset_known);
+	  tree arg = access_node.get_call_arg (stmt);
 
-	  tree arg;
-	  if (access_node->parm_index == MODREF_STATIC_CHAIN_PARM)
-	    arg = gimple_call_chain (stmt);
-	  else
-	    arg = gimple_call_arg (stmt, access_node->parm_index);
+	  if (!arg)
+	    return false;
+
+	  if (integer_zerop (arg) && flag_delete_null_pointer_checks)
+	    continue;
 
 	  ao_ref ref;
-	  poly_offset_int off = (poly_offset_int)access_node->offset
-		+ ((poly_offset_int)access_node->parm_offset
-		   << LOG2_BITS_PER_UNIT);
-	  poly_int64 off2;
-	  if (!off.to_shwi (&off2))
+
+	  if (!access_node.get_ao_ref (stmt, &ref))
 	    return false;
-	  ao_ref_init_from_ptr_and_range
-		 (&ref, arg, true, off2, access_node->size,
-		  access_node->max_size);
 	  ref.ref_alias_set = ref_node->ref;
 	  ref.base_alias_set = base_node->base;
 
