nonzero-3.C: New testcase.

	* g++.dg/tree-ssa/nonzero-3.C: New testcase.
	* tree-vrp.c (nonnull_arg_p): THIS pointers and references are non-zero.
	(gimple_stmt_nonzero_warnv_p): Reference return values are non-zero.

From-SVN: r222054

gcc/ChangeLog

 2015-04-12  Jan Hubicka  <hubicka@ucw.cz>
 
+	* tree-vrp.c (nonnull_arg_p): THIS pointers and references are non-zero.
+	(gimple_stmt_nonzero_warnv_p): Reference return values are non-zero.
+
+2015-04-12  Jan Hubicka  <hubicka@ucw.cz>
+
 	* ipa-profie.c (ipa_profile): Check number of parameters
 	and possible polymorphic call targets before
 	devirtualizing.

gcc/testsuite/ChangeLog

+2015-04-12  Jan Hubicka  <hubicka@ucw.cz>
+
+	* g++.dg/tree-ssa/nonzero-3.C: New testcase.
+
 2015-04-13  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/65204

gcc/testsuite/g++.dg/tree-ssa/nonzero-3.C

+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-vrp1 -fdelete-null-pointer-checks" } */
+struct A {int a;};
+struct B {int b;};
+struct C:A,B {int c;
+  void bar();};
+
+void foo (struct B *);
+void C::bar ()
+{
+  struct C *d = this;
+  foo(this);
+  foo(d);
+}
+void bar (struct C &c)
+{
+  struct C *d = &c;
+  foo(&c);
+  foo(d);
+}
+/* { dg-final { scan-tree-dump-not "if \\(" "vrp1"} } */
+/* { dg-final { cleanup-tree-dump "vrp1" } } */

gcc/tree-vrp.c

@@ -393,6 +393,17 @@ nonnull_arg_p (const_tree arg)
   if (arg == cfun->static_chain_decl)
     return true;
 
+  /* THIS argument of method is always non-NULL.  */
+  if (TREE_CODE (TREE_TYPE (current_function_decl)) == METHOD_TYPE
+      && arg == DECL_ARGUMENTS (current_function_decl)
+      && flag_delete_null_pointer_checks)
+    return true;
+
+  /* Values passed by reference are always non-NULL.  */
+  if (TREE_CODE (TREE_TYPE (arg)) == REFERENCE_TYPE
+      && flag_delete_null_pointer_checks)
+    return true;
+
   fntype = TREE_TYPE (current_function_decl);
   for (attrs = TYPE_ATTRIBUTES (fntype); attrs; attrs = TREE_CHAIN (attrs))
     {
@@ -1216,6 +1227,10 @@ gimple_stmt_nonzero_warnv_p (gimple stmt, bool *strict_overflow_p)
 	    && DECL_IS_OPERATOR_NEW (fndecl)
 	    && !TREE_NOTHROW (fndecl))
 	  return true;
+	/* References are always non-NULL.  */
+	if (flag_delete_null_pointer_checks
+	    && TREE_CODE (TREE_TYPE (fndecl)) == REFERENCE_TYPE)
+	  return true;
 	if (flag_delete_null_pointer_checks && 
 	    lookup_attribute ("returns_nonnull",
 			      TYPE_ATTRIBUTES (gimple_call_fntype (stmt))))