[CMake] Add Python script to generate version script symbol exports

[andrewng]

Summary

Using a Python script instead of the various shell commands means that
it is now possible to cross compile LLVM for Linux on Windows.

[sylvestre.ledru]

llvm/utils/add_llvm_symbol_exports.py

2

please add the copyright section

12

please run black on this file.
Line 7 = 2 spaces
line 11 = 8 spaces

[andrewng]

Update for review comments.

[andrewng]

llvm/utils/add_llvm_symbol_exports.py

12

Sorry about this. Not sure what happened here but a mix of tabs, spaces and tab widths created a bit of a mess!

[sylvestre.ledru]

LGTM

llvm/utils/add_llvm_symbol_exports.py

12

no worries, we should have automation to catch this in a perfect world...

llvm/cmake/modules/AddLLVM.cmake

elseif(${CMAKE_SYSTEM_NAME} MATCHES "AIX")
     set_property(TARGET ${target_name} APPEND_STRING PROPERTY
                  LINK_FLAGS " -Wl,-bE:${export_file}")
   elseif(LLVM_HAVE_LINK_VERSION_SCRIPT)
     # Gold and BFD ld require a version script rather than a plain list.
     set(native_export_file "${target_name}.exports")
     # FIXME: Don't write the "local:" line on OpenBSD.
     # in the export file, also add a linker script to version LLVM symbols (form: LLVM_N.M)
     add_custom_command(OUTPUT ${native_export_file}
-      COMMAND echo "LLVM_${LLVM_VERSION_MAJOR} {" > ${native_export_file}
-      COMMAND grep -q "[[:alnum:]]" ${export_file} && echo "  global:" >> ${native_export_file} || :
-      COMMAND sed -e "s/$/;/" -e "s/^/    /" < ${export_file} >> ${native_export_file}
-      COMMAND echo "  local: *;" >> ${native_export_file}
-      COMMAND echo "};" >> ${native_export_file}
+      COMMAND "${Python3_EXECUTABLE}" ${LLVM_MAIN_SRC_DIR}/utils/add_llvm_symbol_exports.py ${LLVM_VERSION_MAJOR} ${export_file} ${native_export_file}
       DEPENDS ${export_file}
       VERBATIM
       COMMENT "Creating export file for ${target_name}")
     if (${LLVM_LINKER_IS_SOLARISLD})
       set_property(TARGET ${target_name} APPEND_STRING PROPERTY
                    LINK_FLAGS "  -Wl,-M,\"${CMAKE_CURRENT_BINARY_DIR}/${native_export_file}\"")
     else()
       set_property(TARGET ${target_name} APPEND_STRING PROPERTY

llvm/utils/add_llvm_symbol_exports.py

+#!/usr/bin/env python3
+#===----------------------------------------------------------------------===##
+#
+# 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
+#
+#===----------------------------------------------------------------------===##
+
+import os
+import sys
+
+if (len(sys.argv) != 4):
+    print('usage: ' + sys.argv[0] + ' <LLVM major version> <input> <output>')
+    sys.exit(1)
+
+with open(sys.argv[3], 'w') as out_fd:
+    out_fd.write('LLVM_' + sys.argv[1] + ' {\n')
+    if os.stat(sys.argv[2]).st_size > 0:
+        out_fd.write('  global:\n')
+        with open(sys.argv[2], 'r') as in_fd:
+            for e in in_fd.readlines():
+                out_fd.write('    ' + e.rstrip() + ';\n')
+    out_fd.write('  local: *;\n};\n')
+
+sys.exit(0)