Fix integration of pass plugins with llvm dylib

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Summary

• Call llvm_process_pass_plugin from clang when in standalone mode
• bug spotted in https://github.com/llvm/llvm-project/issues/120 and recorded as https://bugs.llvm.org/show_bug.cgi?id=44870

[hans]

I don't know enough about the cmake and dylib build to properly review this. Maybe Tom can help?

Please add a mention of https://github.com/llvm/llvm-project/issues/120 / https://bugs.llvm.org/show_bug.cgi?id=44870 in the change description.

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Need to pull in the symbols, provide the appropriate anchor

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tested with

cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/tmp/inst -DLLVM_LINK_LLVM_DYLIB=ON -DLLVM_BUILD_LLVM_DYLIB=ON   -DLLVM_POLLY_LINK_INTO_TOOLS=ON -DLLVM_TOOL_POLLY_BUILD=ON -DPOLLY_BUNDLED_ISL=ON ../llvm && make -j30  && nm -DC lib/libLLVM-11git.so | grep getPollyPluginInfo

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Also pass with

cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/tmp/inst -DLLVM_LINK_LLVM_DYLIB=OFF -DLLVM_BUILD_LLVM_DYLIB=OFF   -DLLVM_POLLY_LINK_INTO_TOOLS=ON -DLLVM_TOOL_POLLY_BUILD=ON -DPOLLY_BUNDLED_ISL=ON ../llvm && make -j30 && make check-polly -j20

(i.e. when no using DYLIB but still linking polly statically)

and

cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/tmp/inst -DLLVM_LINK_LLVM_DYLIB=OFF -DLLVM_BUILD_LLVM_DYLIB=OFF   -DLLVM_POLLY_LINK_INTO_TOOLS=OFF -DLLVM_TOOL_POLLY_BUILD=ON -DPOLLY_BUNDLED_ISL=ON ../llvm && make -j30 && make check-polly -j20

(i.e. when not using dylib and not linking polly statically)

and

cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/tmp/inst -DLLVM_LINK_LLVM_DYLIB=ON -DLLVM_BUILD_LLVM_DYLIB=ON   -DLLVM_POLLY_LINK_INTO_TOOLS=OFF -DLLVM_TOOL_POLLY_BUILD=ON -DPOLLY_BUNDLED_ISL=ON ../llvm && make -j30 && make check-polly -j20

(i.e. when using dylib but without polly linked in statically)

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But it fails (registered twice) when using LLVM_ENABLE_PROJECTS instead... That's definitively a lot of configuration :-

Actually a configuration issue on my side, everything works file with that config too.

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Totally different, and much cleaner approach of the issue.

[hans]

Looks reasonable to me.

llvm/cmake/modules/AddLLVM.cmake

if(ARG_ADDITIONAL_HEADERS)
     # Pass through ADDITIONAL_HEADERS.
     set(ARG_ADDITIONAL_HEADERS ADDITIONAL_HEADERS ${ARG_ADDITIONAL_HEADERS})
   endif()
   if(ARG_OBJLIBS)
     set(ALL_FILES ${ARG_OBJLIBS})
   else()
     llvm_process_sources(ALL_FILES ${ARG_UNPARSED_ARGUMENTS} ${ARG_ADDITIONAL_HEADERS})
   endif()
-  if(ARG_ENABLE_PLUGINS)
+  if(ARG_ENABLE_PLUGINS) 
+    if(ARG_DISABLE_LLVM_LINK_LLVM_DYLIB OR NOT ARG_LLVM_LINK_LLVM_DYLIB)
       set_property(GLOBAL APPEND PROPERTY LLVM_PLUGIN_TARGETS ${name})
     endif()
+  endif()
 
   if(ARG_MODULE)
     if(ARG_SHARED OR ARG_STATIC)
       message(WARNING "MODULE with SHARED|STATIC doesn't make sense.")
     endif()
     # Plugins that link against a tool are allowed even when plugins in general are not
     if(NOT LLVM_ENABLE_PLUGINS AND NOT (ARG_PLUGIN_TOOL AND LLVM_EXPORT_SYMBOLS_FOR_PLUGINS))
       message(STATUS "${name} ignored -- Loadable modules not supported on this platform.")
if(NOT ARG_IGNORE_EXTERNALIZE_DEBUGINFO)
     llvm_externalize_debuginfo(${name})
   endif()
   if (LLVM_PTHREAD_LIB)
     # libpthreads overrides some standard library symbols, so main
     # executable must be linked with it in order to provide consistent
     # API for all shared libaries loaded by this executable.
     target_link_libraries(${name} PRIVATE ${LLVM_PTHREAD_LIB})
   endif()
-  if(ARG_ENABLE_PLUGINS)
+  if(ARG_ENABLE_PLUGINS AND NOT LLVM_LINK_LLVM_DYLIB)
     set_property(GLOBAL APPEND PROPERTY LLVM_PLUGIN_TARGETS ${name})
   endif()
 
   llvm_codesign(${name} ENTITLEMENTS ${ARG_ENTITLEMENTS} BUNDLE_PATH ${ARG_BUNDLE_PATH})
 endmacro(add_llvm_executable name)
 
 # add_llvm_pass_plugin(name [NO_MODULE] ...)
 #   Add ${name} as an llvm plugin.

llvm/lib/Passes/PassPlugin.cpp

Expected<PassPlugin> PassPlugin::Load(const std::string &Filename) {
 
   if (!P.Info.RegisterPassBuilderCallbacks)
     return make_error<StringError>(Twine("Empty entry callback in plugin '") +
                                        Filename + "'.'",
                                    inconvertibleErrorCode());
 
   return P;
 }
+
+// Provide an anchor that pull statically linked plugin symbols.
+#define HANDLE_EXTENSION(Ext)                                                  \
+  llvm::PassPluginLibraryInfo get##Ext##PluginInfo();
+#include "llvm/Support/Extension.def"
+
+llvm::PassPluginLibraryInfo (*PluginsAnchor[])() = {
+#define HANDLE_EXTENSION(Ext)                                                  \
+  get##Ext##PluginInfo,
+#include "llvm/Support/Extension.def"
+  nullptr
+};

llvm/tools/llvm-shlib/CMakeLists.txt

if(LLVM_BUILD_LLVM_DYLIB)
   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()
 
   if (LLVM_LINK_LLVM_DYLIB)
     set(INSTALL_WITH_TOOLCHAIN INSTALL_WITH_TOOLCHAIN)
   endif()
-  add_llvm_library(LLVM SHARED DISABLE_LLVM_LINK_LLVM_DYLIB SONAME ${INSTALL_WITH_TOOLCHAIN} ${SOURCES})
+  add_llvm_library(LLVM SHARED DISABLE_LLVM_LINK_LLVM_DYLIB ENABLE_PLUGINS SONAME ${INSTALL_WITH_TOOLCHAIN} ${SOURCES})
 
   list(REMOVE_DUPLICATES LIB_NAMES)
   if(("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux") OR (MINGW) OR (HAIKU)
      OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "FreeBSD")
      OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "GNU")
      OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "OpenBSD")
      OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "Fuchsia")
      OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "DragonFly")
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} INSTALL_WITH_TOOLCHAIN)
+  add_llvm_library(LLVM-C SHARED ${SOURCES} INSTALL_WITH_TOOLCHAIN ENABLE_PLUGINS)
   
   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)
 
   add_custom_command(OUTPUT ${LLVM_EXPORTED_SYMBOL_FILE}
     COMMAND ${PYTHON_EXECUTABLE} ${GEN_SCRIPT} --libsfile ${LIBSFILE} ${GEN_UNDERSCORE} --nm "${llvm_nm}" -o ${LLVM_EXPORTED_SYMBOL_FILE}
     DEPENDS ${LIB_NAMES} ${llvm_nm_target}
     COMMENT "Generating export list for LLVM-C"
     VERBATIM )
 
   # Finally link the target.
-  add_llvm_library(LLVM-C SHARED INSTALL_WITH_TOOLCHAIN ${SOURCES} DEPENDS intrinsics_gen)
+  add_llvm_library(LLVM-C SHARED INSTALL_WITH_TOOLCHAIN ENABLE_PLUGINS ${SOURCES} DEPENDS intrinsics_gen)
 
 endif()

polly/lib/CMakeLists.txt

 
 # Polly-ACC requires the NVPTX backend to work. Ask LLVM about its libraries.
 set(nvptx_libs)
 if (GPU_CODEGEN)
   # This call emits an error if they NVPTX backend is not enable.
   llvm_map_components_to_libnames(nvptx_libs NVPTX)
 endif ()
 
-if (LLVM_LINK_LLVM_DYLIB)
-  # The shlib/dylib contains all the LLVM components
-  # (including NVPTX is enabled) already. Adding them to target_link_libraries
-  # would cause them being twice in the address space
-  # (their LLVM*.a/so and their copies in libLLVM.so)
-  # which results in errors when the two instances try to register the same
-  # command-line switches.
-  target_link_libraries(Polly PUBLIC LLVM)
-else ()
+if (NOT LLVM_LINK_LLVM_DYLIB)
   target_link_libraries(Polly PUBLIC
     LLVMSupport
     LLVMCore
     LLVMScalarOpts
     LLVMInstCombine
     LLVMTransformUtils
     LLVMAnalysis
     LLVMipo