--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/flang/runtime/main.cpp	Mon May 25 11:55:54 2020 +0900
@@ -0,0 +1,36 @@
+//===-- runtime/main.cpp ----------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "main.h"
+#include "environment.h"
+#include "terminator.h"
+#include <cfenv>
+#include <cstdio>
+#include <cstdlib>
+
+static void ConfigureFloatingPoint() {
+#ifdef feclearexcept // a macro in some environments; omit std::
+  feclearexcept(FE_ALL_EXCEPT);
+#else
+  std::feclearexcept(FE_ALL_EXCEPT);
+#endif
+#ifdef fesetround
+  fesetround(FE_TONEAREST);
+#else
+  std::fesetround(FE_TONEAREST);
+#endif
+}
+
+extern "C" {
+void RTNAME(ProgramStart)(int argc, const char *argv[], const char *envp[]) {
+  std::atexit(Fortran::runtime::NotifyOtherImagesOfNormalEnd);
+  Fortran::runtime::executionEnvironment.Configure(argc, argv, envp);
+  ConfigureFloatingPoint();
+  // I/O is initialized on demand so that it works for non-Fortran main().
+}
+}