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llvm-mirror/tools/llvm-shlib/CMakeLists.txt
David Bolvansky cec4dea4a3 [RFC] Build LLVM-C.dll on MSVC that exports only the C API
Summary:
Hello!

This commit adds a LLVM-C target that is always built on MSVC. A big fat warning, this is my first cmake code ever so there is a fair bit of I-have-no-idea-what-I'm-doing going on here. Which is also why I placed it outside of llvm-shlib as I was afraid of breaking things of other people. Secondly llvm-shlib builds a LLVM.so which exports all symbols and then does a thin library that points to it, but on Windows we do not build a LLVM.dll so that would have complicated the code more.

The patch includes a python script that calls dumpbin.exe to get all of the symbols from the built libraries. It then grabs all the symbols starting with LLVM and generates the export file from those. The export file is then used to create the library just like the LLVM-C that is built on darwin.

Improvements that I need help with, to follow up this review.
  - Get cmake to make sure that dumpbin.exe is on the path and wire the full path to the script.
  - Use LLVM-C.dll when building llvm-c-test so we can verify that the symbols are exported.
  - Bundle the LLVM-C.dll with the windows installer.

Why do this?  I'm building a language frontend which is self-hosting, and on windows because of various tooling issues we have a problem of consuming the LLVM*.lib directly on windows. Me and the users of my projects using LLVM would be greatly helped by having LLVM-C.dll built and shipped by the Windows installer. Not only does LLVM takes forever to build, you have to run a extra python script in order to get the final DLL.

Any comments, thoughts or help is greatly appreciated.

Cheers, Jakob.

Patch by: Wallbraker (Jakob Bornecrantz)

Reviewers: compnerd, beanz, hans, smeenai

Reviewed By: beanz

Subscribers: xbolva00, bhelyer, Memnarch, rnk, fedor.sergeev, chapuni, smeenai, john.brawn, deadalnix, llvm-commits, mgorny

Differential Revision: https://reviews.llvm.org/D35077

llvm-svn: 339151
2018-08-07 15:54:50 +00:00

154 lines
5.7 KiB
CMake

# This tool creates a shared library from the LLVM libraries. Generating this
# library is enabled by setting LLVM_BUILD_LLVM_DYLIB=yes on the CMake
# commandline. By default the shared library only exports the LLVM C API.
set(SOURCES
libllvm.cpp
)
if(LLVM_LINK_LLVM_DYLIB AND LLVM_DYLIB_EXPORTED_SYMBOL_FILE)
message(WARNING "Using LLVM_LINK_LLVM_DYLIB with LLVM_DYLIB_EXPORTED_SYMBOL_FILE may not work. Use at your own risk.")
endif()
if(LLVM_BUILD_LLVM_DYLIB)
if(MSVC)
message(FATAL_ERROR "Generating libLLVM is not supported on MSVC")
endif()
llvm_map_components_to_libnames(LIB_NAMES ${LLVM_DYLIB_COMPONENTS})
# libLLVM.so should not have any dependencies on any other LLVM
# shared libraries. When using the "all" pseudo-component,
# LLVM_AVAILABLE_LIBS is added to the dependencies, which may
# contain shared libraries (e.g. libLTO).
#
# Also exclude libLLVMTableGen for the following reasons:
# - it is only used by internal *-tblgen utilities;
# - it pollutes the global options space.
foreach(lib ${LIB_NAMES})
get_target_property(t ${lib} TYPE)
if("${lib}" STREQUAL "LLVMTableGen")
elseif("x${t}" STREQUAL "xSTATIC_LIBRARY")
list(APPEND FILTERED_LIB_NAMES ${lib})
endif()
endforeach()
set(LIB_NAMES ${FILTERED_LIB_NAMES})
if(LLVM_DYLIB_EXPORTED_SYMBOL_FILE)
set(LLVM_EXPORTED_SYMBOL_FILE ${LLVM_DYLIB_EXPORTED_SYMBOL_FILE})
add_custom_target(libLLVMExports DEPENDS ${LLVM_EXPORTED_SYMBOL_FILE})
endif()
add_llvm_library(LLVM SHARED DISABLE_LLVM_LINK_LLVM_DYLIB SONAME ${SOURCES})
list(REMOVE_DUPLICATES LIB_NAMES)
if(("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux") OR (MINGW) OR (HAIKU)
OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "FreeBSD")
OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "OpenBSD")
OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "Fuchsia")
OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "DragonFly")
OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "SunOS")) # FIXME: It should be "GNU ld for elf"
configure_file(
${CMAKE_CURRENT_SOURCE_DIR}/simple_version_script.map.in
${LLVM_LIBRARY_DIR}/tools/llvm-shlib/simple_version_script.map)
# GNU ld doesn't resolve symbols in the version script.
set(LIB_NAMES -Wl,--whole-archive ${LIB_NAMES} -Wl,--no-whole-archive)
if (NOT LLVM_LINKER_IS_SOLARISLD)
# Solaris ld does not accept global: *; so there is no way to version *all* global symbols
set(LIB_NAMES -Wl,--version-script,${LLVM_LIBRARY_DIR}/tools/llvm-shlib/simple_version_script.map ${LIB_NAMES})
endif()
elseif("${CMAKE_SYSTEM_NAME}" STREQUAL "Darwin")
set(LIB_NAMES -Wl,-all_load ${LIB_NAMES})
endif()
target_link_libraries(LLVM PRIVATE ${LIB_NAMES})
if (APPLE)
set_property(TARGET LLVM APPEND_STRING PROPERTY
LINK_FLAGS
" -compatibility_version 1 -current_version ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH}")
endif()
if(TARGET libLLVMExports)
add_dependencies(LLVM libLLVMExports)
endif()
endif()
if(LLVM_BUILD_LLVM_C_DYLIB AND NOT MSVC)
if(NOT APPLE)
message(FATAL_ERROR "Generating libLLVM-c is only supported on Darwin")
endif()
if(NOT LLVM_BUILD_LLVM_DYLIB)
message(FATAL_ERROR "Generating libLLVM-c requires LLVM_BUILD_LLVM_C_DYLIB on Darwin")
endif()
# To get the export list for a single llvm library:
# nm ${LIB_PATH} | awk "/T _LLVM/ { print $3 }" | sort -u | sed -e "s/^_//g" > ${LIB_PATH}.exports
set(LLVM_EXPORTED_SYMBOL_FILE ${CMAKE_BINARY_DIR}/libllvm-c.exports)
set(LIB_DIR ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib${LLVM_LIBDIR_SUFFIX})
set(LIB_NAME ${LIB_DIR}/${CMAKE_SHARED_LIBRARY_PREFIX}LLVM)
set(LIB_PATH ${LIB_NAME}${CMAKE_SHARED_LIBRARY_SUFFIX})
set(LIB_EXPORTS_PATH ${LIB_NAME}.exports)
list(APPEND LLVM_DYLIB_REQUIRED_EXPORTS ${LIB_EXPORTS_PATH})
add_custom_command(OUTPUT ${LLVM_EXPORTED_SYMBOL_FILE}
COMMAND nm ${LIB_PATH} | awk "/T _LLVM/ || /T LLVM/ { print $3 }" | sort -u | sed -e "s/^_//g" > ${LLVM_EXPORTED_SYMBOL_FILE}
WORKING_DIRECTORY ${LIB_DIR}
DEPENDS LLVM
COMMENT "Generating Export list for LLVM..."
VERBATIM )
add_custom_target(libLLVMCExports DEPENDS ${LLVM_EXPORTED_SYMBOL_FILE})
add_llvm_library(LLVM-C SHARED ${SOURCES})
target_link_libraries(LLVM-C PUBLIC LLVM)
add_dependencies(LLVM-C libLLVMCExports)
set_property(TARGET LLVM-C APPEND_STRING PROPERTY
LINK_FLAGS
" -compatibility_version 1 -current_version ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH} -Wl,-reexport_library ${LIB_PATH}")
endif()
if(MSVC)
# Build the LLVM-C.dll library that exports the C API.
set(LLVM_LINK_COMPONENTS
${LLVM_DYLIB_COMPONENTS}
)
llvm_map_components_to_libnames(LIB_NAMES ${LLVM_DYLIB_COMPONENTS})
list(REMOVE_DUPLICATES LIB_NAMES)
# The python script needs to know whether symbols are prefixed with underscores or not.
if(LLVM_HOST_TRIPLE STREQUAL "i686-pc-win32")
set(GEN_UNDERSCORE "--underscore")
else()
set(GEN_UNDERSCORE "")
endif()
# Get the full name to the libs so the python script understands them.
foreach(lib ${LIB_NAMES})
list(APPEND FULL_LIB_NAMES ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib/${lib}.lib)
endforeach()
# Generate the exports file dynamically.
set(GEN_SCRIPT ${CMAKE_CURRENT_SOURCE_DIR}/gen-msvc-exports.py)
set(LLVM_EXPORTED_SYMBOL_FILE ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/libllvm-c.exports)
add_custom_command(OUTPUT ${LLVM_EXPORTED_SYMBOL_FILE}
COMMAND ${PYTHON_EXECUTABLE} ${GEN_SCRIPT} ${FULL_LIB_NAMES} ${GEN_UNDERSCORE} --nm ${LLVM_TOOLS_BINARY_DIR}/llvm-nm -o ${LLVM_EXPORTED_SYMBOL_FILE}
DEPENDS ${LIB_NAMES} llvm-nm
COMMENT "Generating export list for LLVM-C"
VERBATIM )
# Finally link the target.
add_llvm_library(LLVM-C SHARED ${SOURCES} DEPENDS intrinsics_gen)
endif()