commit fff3a6ba06e4942c77ada0e8c5c6f6706eb99c1d
author Jean Perier <jperier@nvidia.com> Thu Sep 30 06:26:00 2021 -0700
committer Copybara-Service <copybara-worker@google.com> Thu Sep 30 23:52:11 2021 -0700
tree 04abdb3a4f824acc3e22226e3e47d40d7c60bff6
parent 9f13dc2c38afa9038b71e7746da4f609593f3a70

[flang] Add a wrapper for Fortran main program

Add a C wrapper that calls the Fortran runtime initialization and
finalization routines as well as the compiled Fortran main program
_QQmain.

Place it in its own library to satisfy shared library builds since it
contains a C main function.

- https://github.com/flang-compiler/f18-llvm-project/commit/cc7ac498f916d32a9b197d3ace816f4de5d36aad#diff-fa35a5efa62731fd2845e5e982eca9a2e36439783e11a4e4a463753c2160ec10R53
- was created in flang/test/Examples/main.c in Eric's branch

GitOrigin-RevId: 2c1ce0755e09909c41db93845c4c3f42457cb9c8

cmake/modules/AddFlang.cmake

diff --git a/cmake/modules/AddFlang.cmake b/cmake/modules/AddFlang.cmake
index 5da58a5..82a3142 100644
--- a/cmake/modules/AddFlang.cmake
+++ b/cmake/modules/AddFlang.cmake
@@ -17,7 +17,7 @@
 
 macro(add_flang_library name)
   cmake_parse_arguments(ARG
-    "SHARED"
+    "SHARED;STATIC"
     ""
     "ADDITIONAL_HEADERS"
     ${ARGN})
@@ -52,7 +52,7 @@
   else()
     # llvm_add_library ignores BUILD_SHARED_LIBS if STATIC is explicitly set,
     # so we need to handle it here.
-    if (BUILD_SHARED_LIBS)
+    if (BUILD_SHARED_LIBS AND NOT ARG_STATIC)
       set(LIBTYPE SHARED OBJECT)
     else()
       set(LIBTYPE STATIC OBJECT)

runtime/CMakeLists.txt

diff --git a/runtime/CMakeLists.txt b/runtime/CMakeLists.txt
index b3e96fa..d7b6b79 100644
--- a/runtime/CMakeLists.txt
+++ b/runtime/CMakeLists.txt
@@ -1,15 +1,9 @@
-#===-- runtime/CMakeLists.txt ----------------------------------------------===#
-#
-# 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(CheckCXXSymbolExists)
 include(CheckCXXSourceCompiles)
 check_cxx_symbol_exists(strerror string.h HAVE_STRERROR)
 check_cxx_symbol_exists(strerror_r string.h HAVE_STRERROR_R)
+
 # Can't use symbol exists here as the function is overloaded in C++
 check_cxx_source_compiles(
   "#include <string.h>
@@ -30,7 +24,7 @@
 # with different names
 include_directories(AFTER ${CMAKE_CURRENT_BINARY_DIR})
 
-add_flang_library(FortranRuntime
+add_flang_library(FortranRuntime PARTIAL_SOURCES_INTENDED
   ISO_Fortran_binding.cpp
   allocatable.cpp
   assign.cpp
@@ -82,3 +76,7 @@
   LINK_LIBS
   FortranDecimal
 )
+
+add_flang_library(Fortran_main STATIC PARTIAL_SOURCES_INTENDED
+  Fortran_main.c
+)

runtime/Fortran_main.c

diff --git a/runtime/Fortran_main.c b/runtime/Fortran_main.c
new file mode 100644
index 0000000..88f0cdb
--- /dev/null
+++ b/runtime/Fortran_main.c
@@ -0,0 +1,14 @@
+#include "flang/Runtime/main.h"
+#include "flang/Runtime/stop.h"
+
+/* main entry into PROGRAM */
+void _QQmain();
+
+/* C main stub */
+int main(int argc, const char *argv[], const char *envp[])
+{
+  RTNAME(ProgramStart)(argc, argv, envp);
+  _QQmain();
+  RTNAME(ProgramEndStatement)();
+  return 0;
+}