--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/gimple-ssa-nonnull-compare.c	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,152 @@
+/* -Wnonnull-compare warning support.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   Contributed by Jakub Jelinek <jakub@redhat.com>
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "backend.h"
+#include "tree.h"
+#include "gimple.h"
+#include "tree-pass.h"
+#include "ssa.h"
+#include "diagnostic-core.h"
+#include "tree-dfa.h"
+
+/* Warn about comparison of nonnull_arg_p argument initial values
+   with NULL.  */
+
+static void
+do_warn_nonnull_compare (function *fun, tree arg)
+{
+  if (!POINTER_TYPE_P (TREE_TYPE (arg))
+      && TREE_CODE (TREE_TYPE (arg)) != OFFSET_TYPE)
+    return;
+
+  if (!nonnull_arg_p (arg))
+    return;
+
+  tree d = ssa_default_def (fun, arg);
+  if (d == NULL_TREE)
+    return;
+
+  use_operand_p use_p;
+  imm_use_iterator iter;
+
+  FOR_EACH_IMM_USE_FAST (use_p, iter, d)
+    {
+      gimple *stmt = USE_STMT (use_p);
+      tree op = NULL_TREE;
+      location_t loc = gimple_location (stmt);
+      if (gimple_code (stmt) == GIMPLE_COND)
+	switch (gimple_cond_code (stmt))
+	  {
+	  case EQ_EXPR:
+	  case NE_EXPR:
+	    if (gimple_cond_lhs (stmt) == d)
+	      op = gimple_cond_rhs (stmt);
+	    break;
+	  default:
+	    break;
+	  }
+      else if (is_gimple_assign (stmt))
+	switch (gimple_assign_rhs_code (stmt))
+	  {
+	  case EQ_EXPR:
+	  case NE_EXPR:
+	    if (gimple_assign_rhs1 (stmt) == d)
+	      op = gimple_assign_rhs2 (stmt);
+	    break;
+	  case COND_EXPR:
+	    switch (TREE_CODE (gimple_assign_rhs1 (stmt)))
+	      {
+	      case EQ_EXPR:
+	      case NE_EXPR:
+		op = gimple_assign_rhs1 (stmt);
+		if (TREE_OPERAND (op, 0) != d)
+		  {
+		    op = NULL_TREE;
+		    break;
+		  }
+		loc = EXPR_LOC_OR_LOC (op, loc);
+		op = TREE_OPERAND (op, 1);
+		break;
+	      default:
+		break;
+	      }
+	    break;
+	  default:
+	    break;
+	  }
+      if (op
+	  && (POINTER_TYPE_P (TREE_TYPE (arg))
+	      ? integer_zerop (op) : integer_minus_onep (op))
+	  && !gimple_no_warning_p (stmt))
+	warning_at (loc, OPT_Wnonnull_compare,
+		    "nonnull argument %qD compared to NULL", arg);
+    }
+}
+
+namespace {
+
+const pass_data pass_data_warn_nonnull_compare =
+{
+  GIMPLE_PASS, /* type */
+  "*nonnullcmp", /* name */
+  OPTGROUP_NONE, /* optinfo_flags */
+  TV_NONE, /* tv_id */
+  PROP_ssa, /* properties_required */
+  0, /* properties_provided */
+  0, /* properties_destroyed */
+  0, /* todo_flags_start */
+  0, /* todo_flags_finish */
+};
+
+class pass_warn_nonnull_compare : public gimple_opt_pass
+{
+public:
+  pass_warn_nonnull_compare (gcc::context *ctxt)
+    : gimple_opt_pass (pass_data_warn_nonnull_compare, ctxt)
+  {}
+
+  /* opt_pass methods: */
+  virtual bool gate (function *) { return warn_nonnull_compare; }
+
+  virtual unsigned int execute (function *);
+
+}; // class pass_warn_nonnull_compare
+
+unsigned int
+pass_warn_nonnull_compare::execute (function *fun)
+{
+  if (fun->static_chain_decl)
+    do_warn_nonnull_compare (fun, fun->static_chain_decl);
+
+  for (tree arg = DECL_ARGUMENTS (cfun->decl); arg; arg = DECL_CHAIN (arg))
+    do_warn_nonnull_compare (fun, arg);
+  return 0;
+}
+
+} // anon namespace
+
+gimple_opt_pass *
+make_pass_warn_nonnull_compare (gcc::context *ctxt)
+{
+  return new pass_warn_nonnull_compare (ctxt);
+}