[flang] Define the API for CPU_TIME

CPU_TIME takes a single real scalar INTENT(OUT) argument. We can
therefore return a double and let lowering handle casting that to the
precision used for the default real kind.

Differential Revision: https://reviews.llvm.org/D103805

1 files changed, 27 insertions, 0 deletions

diff --git a/flang/runtime/time-intrinsic.h b/flang/runtime/time-intrinsic.h
new file mode 100644
index 0000000..835f24c
--- /dev/null
+++ b/flang/runtime/time-intrinsic.h
@@ -0,0 +1,27 @@
+//===-- runtime/time-intrinsic.h --------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+// Defines the API between compiled code and the implementations of time-related
+// intrinsic subroutines in the runtime library.
+
+#ifndef FORTRAN_RUNTIME_TIME_INTRINSIC_H_
+#define FORTRAN_RUNTIME_TIME_INTRINSIC_H_
+
+#include "cpp-type.h"
+#include "entry-names.h"
+
+namespace Fortran::runtime {
+extern "C" {
+
+// Lowering may need to cast this result to match the precision of the default
+// real kind.
+double RTNAME(CpuTime)();
+
+} // extern "C"
+} // namespace Fortran::runtime
+#endif // FORTRAN_RUNTIME_TIME_INTRINSIC_H_