Don't export symbols from clang/opt/llc if plugins are disabled.

[efriedma]

Summary

The only reason we export symbols from these tools is to support plugins; if we don't have plugins, exporting symbols just bloats the executable and makes LTO less effective.

See review of D75879 for the discussion that led to this patch.

clang/tools/driver/CMakeLists.txt

 if(WIN32 AND NOT CYGWIN)
   # Prevent versioning if the buildhost is targeting for Win32.
 else()
   set_target_properties(clang PROPERTIES VERSION ${CLANG_EXECUTABLE_VERSION})
 endif()
 
 # Support plugins.
 if(CLANG_PLUGIN_SUPPORT)
-  export_executable_symbols(clang)
+  export_executable_symbols_for_plugins(clang)
 endif()
 
 add_dependencies(clang clang-resource-headers)
 
 if(NOT CLANG_LINKS_TO_CREATE)
   set(CLANG_LINKS_TO_CREATE clang++ clang-cl clang-cpp)
 endif()
 

llvm/cmake/modules/AddLLVM.cmake

elseif(NOT (WIN32 OR CYGWIN))
     set_target_properties(${target} PROPERTIES ENABLE_EXPORTS 1)
     if (APPLE)
       set_property(TARGET ${target} APPEND_STRING PROPERTY
         LINK_FLAGS " -rdynamic")
     endif()
   endif()
 endfunction()
 
+# Export symbols if LLVM plugins are enabled.
+function(export_executable_symbols_for_plugins target)
+  if(LLVM_ENABLE_PLUGINS)
+    export_executable_symbols(${target})
+  endif()
+endfunction()
+
 if(NOT LLVM_TOOLCHAIN_TOOLS)
   set (LLVM_TOOLCHAIN_TOOLS
     llvm-ar
     llvm-cov
     llvm-cxxfilt
     llvm-ranlib
     llvm-lib
     llvm-nm

llvm/tools/bugpoint/CMakeLists.txt

add_llvm_tool(bugpoint
   bugpoint.cpp
 
   ENABLE_PLUGINS
 
   DEPENDS
   intrinsics_gen
   SUPPORT_PLUGINS
   )
-export_executable_symbols(bugpoint)
+export_executable_symbols_for_plugins(bugpoint)

llvm/tools/llc/CMakeLists.txt

 add_llvm_tool(llc
   llc.cpp
 
   DEPENDS
   intrinsics_gen
   SUPPORT_PLUGINS
   )
 
-export_executable_symbols(llc)
+export_executable_symbols_for_plugins(llc)

llvm/tools/llvm-stress/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
   Analysis
   Core
   Support
   )
 
 add_llvm_tool(llvm-stress
   llvm-stress.cpp
 
   DEPENDS
   intrinsics_gen
   )
-export_executable_symbols(llvm-stress)

llvm/tools/opt/CMakeLists.txt

add_llvm_tool(opt
   opt.cpp
 
   ENABLE_PLUGINS
 
   DEPENDS
   intrinsics_gen
   SUPPORT_PLUGINS
   )
-export_executable_symbols(opt)
+export_executable_symbols_for_plugins(opt)
 
 if(LLVM_BUILD_EXAMPLES)
     target_link_libraries(opt PRIVATE ExampleIRTransforms)
 endif(LLVM_BUILD_EXAMPLES)

llvm/unittests/Passes/CMakeLists.txt

 # but expects them to exist in the process loading the plugin. This doesn't
 # work with DLLs on Windows (where a shared library can't have undefined
 # references), so just skip this testcase on Windows.
 if (NOT WIN32)
   set(LLVM_LINK_COMPONENTS Support Passes Core)
   add_llvm_unittest(PluginsTests
     PluginsTest.cpp
     )
-  export_executable_symbols(PluginsTests)
+  export_executable_symbols_for_plugins(PluginsTests)
   target_link_libraries(PluginsTests PRIVATE LLVMTestingSupport)
 
   set(LLVM_LINK_COMPONENTS)
   add_llvm_library(TestPlugin MODULE BUILDTREE_ONLY
     TestPlugin.cpp
     )
 
   # Put plugin next to the unit test executable.