--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/c/c-convert.c	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,169 @@
+/* Language-level data type conversion for GNU C.
+   Copyright (C) 1987-2017 Free Software Foundation, Inc.
+
+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/>.  */
+
+
+/* This file contains the functions for converting C expressions
+   to different data types.  The only entry point is `convert'.
+   Every language front end must have a `convert' function
+   but what kind of conversions it does will depend on the language.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "target.h"
+#include "c-tree.h"
+#include "convert.h"
+#include "langhooks.h"
+#include "ubsan.h"
+#include "stringpool.h"
+#include "attribs.h"
+#include "asan.h"
+
+/* Change of width--truncation and extension of integers or reals--
+   is represented with NOP_EXPR.  Proper functioning of many things
+   assumes that no other conversions can be NOP_EXPRs.
+
+   Conversion between integer and pointer is represented with CONVERT_EXPR.
+   Converting integer to real uses FLOAT_EXPR
+   and real to integer uses FIX_TRUNC_EXPR.
+
+   Here is a list of all the functions that assume that widening and
+   narrowing is always done with a NOP_EXPR:
+     In convert.c, convert_to_integer.
+     In c-typeck.c, build_binary_op (boolean ops), and
+	c_common_truthvalue_conversion.
+     In expr.c: expand_expr, for operands of a MULT_EXPR.
+     In fold-const.c: fold.
+     In tree.c: get_narrower and get_unwidened.  */
+
+/* Subroutines of `convert'.  */
+
+
+
+/* Create an expression whose value is that of EXPR,
+   converted to type TYPE.  The TREE_TYPE of the value
+   is always TYPE.  This function implements all reasonable
+   conversions; callers should filter out those that are
+   not permitted by the language being compiled.  */
+
+tree
+convert (tree type, tree expr)
+{
+  tree e = expr;
+  enum tree_code code = TREE_CODE (type);
+  const char *invalid_conv_diag;
+  tree ret;
+  location_t loc = EXPR_LOCATION (expr);
+
+  if (type == error_mark_node
+      || error_operand_p (expr))
+    return error_mark_node;
+
+  if ((invalid_conv_diag
+       = targetm.invalid_conversion (TREE_TYPE (expr), type)))
+    {
+      error (invalid_conv_diag);
+      return error_mark_node;
+    }
+
+  if (type == TREE_TYPE (expr))
+    return expr;
+  ret = targetm.convert_to_type (type, expr);
+  if (ret)
+      return ret;
+
+  STRIP_TYPE_NOPS (e);
+
+  if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr))
+      && (TREE_CODE (TREE_TYPE (expr)) != COMPLEX_TYPE
+	  || TREE_CODE (e) == COMPLEX_EXPR))
+    return fold_convert_loc (loc, type, expr);
+  if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)
+    return error_mark_node;
+  if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE)
+    {
+      error ("void value not ignored as it ought to be");
+      return error_mark_node;
+    }
+
+  switch (code)
+    {
+    case VOID_TYPE:
+      return fold_convert_loc (loc, type, e);
+
+    case INTEGER_TYPE:
+    case ENUMERAL_TYPE:
+      if (sanitize_flags_p (SANITIZE_FLOAT_CAST)
+	  && current_function_decl != NULL_TREE
+	  && TREE_CODE (TREE_TYPE (expr)) == REAL_TYPE
+	  && COMPLETE_TYPE_P (type))
+	{
+	  expr = save_expr (expr);
+	  tree check = ubsan_instrument_float_cast (loc, type, expr);
+	  expr = fold_build1 (FIX_TRUNC_EXPR, type, expr);
+	  if (check == NULL_TREE)
+	    return expr;
+	  return fold_build2 (COMPOUND_EXPR, TREE_TYPE (expr), check, expr);
+	}
+      ret = convert_to_integer (type, e);
+      goto maybe_fold;
+
+    case BOOLEAN_TYPE:
+      return fold_convert_loc
+	(loc, type, c_objc_common_truthvalue_conversion (input_location, expr));
+
+    case POINTER_TYPE:
+    case REFERENCE_TYPE:
+      ret = convert_to_pointer (type, e);
+      goto maybe_fold;
+
+    case REAL_TYPE:
+      ret = convert_to_real (type, e);
+      goto maybe_fold;
+
+    case FIXED_POINT_TYPE:
+      ret = convert_to_fixed (type, e);
+      goto maybe_fold;
+
+    case COMPLEX_TYPE:
+      ret = convert_to_complex (type, e);
+      goto maybe_fold;
+
+    case VECTOR_TYPE:
+      ret = convert_to_vector (type, e);
+      goto maybe_fold;
+
+    case RECORD_TYPE:
+    case UNION_TYPE:
+      if (lang_hooks.types_compatible_p (type, TREE_TYPE (expr)))
+	return e;
+      break;
+
+    default:
+      break;
+
+    maybe_fold:
+      if (TREE_CODE (ret) != C_MAYBE_CONST_EXPR)
+	ret = fold (ret);
+      return ret;
+    }
+
+  error ("conversion to non-scalar type requested");
+  return error_mark_node;
+}