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

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.

Differential Revision: https://reviews.llvm.org/D76527

cmake/modules/AddLLVM.cmake

@@ -1029,6 +1029,13 @@ function(export_executable_symbols target)
   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

tools/bugpoint/CMakeLists.txt

@@ -38,4 +38,4 @@ add_llvm_tool(bugpoint
   intrinsics_gen
   SUPPORT_PLUGINS
   )
-export_executable_symbols(bugpoint)
+export_executable_symbols_for_plugins(bugpoint)

tools/llc/CMakeLists.txt

@@ -27,4 +27,4 @@ add_llvm_tool(llc
   SUPPORT_PLUGINS
   )
 
-export_executable_symbols(llc)
+export_executable_symbols_for_plugins(llc)

tools/llvm-stress/CMakeLists.txt

@@ -10,4 +10,3 @@ add_llvm_tool(llvm-stress
   DEPENDS
   intrinsics_gen
   )
-export_executable_symbols(llvm-stress)

tools/opt/CMakeLists.txt

@@ -39,7 +39,7 @@ add_llvm_tool(opt
   intrinsics_gen
   SUPPORT_PLUGINS
   )
-export_executable_symbols(opt)
+export_executable_symbols_for_plugins(opt)
 
 if(LLVM_BUILD_EXAMPLES)
     target_link_libraries(opt PRIVATE ExampleIRTransforms)

unittests/Passes/CMakeLists.txt

@@ -16,7 +16,7 @@ if (NOT WIN32)
   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)