[Polly][CMake] Fix exports (#122123)

If Polly is built with LLVM_POLLY_LINK_INTO_TOOLS=ON (the default for
monorepo builds), then Polly will become a dependency of the
LLVMExtensions component, which is part of LLVMExports. As such, all the
Polly libraries also have to be part of LLVMExports.

However, if Polly is built with LLVM_POLLY_LINK_INTO_TOOLS=OFF, we also
end up adding Polly libraries to LLVMExports. This is undesirable, as it
adds a hard dependency from llvm on polly.

Fix this by only exporting polly libraries from LLVMExports if
LLVM_POLLY_LINK_INTO_TOOLS is enabled.

Author: nikic

llvm/cmake/modules/AddLLVM.cmake

@@ -1220,9 +1220,9 @@ function(add_llvm_pass_plugin name)
     endif()
     set_property(GLOBAL APPEND PROPERTY LLVM_STATIC_EXTENSIONS ${name})
   elseif(NOT ARG_NO_MODULE)
-    add_llvm_library(${name} MODULE ${ARG_UNPARSED_ARGUMENTS})
+    add_llvm_library(${name} MODULE NO_EXPORT ${ARG_UNPARSED_ARGUMENTS})
   else()
-    add_llvm_library(${name} OBJECT ${ARG_UNPARSED_ARGUMENTS})
+    add_llvm_library(${name} OBJECT NO_EXPORT ${ARG_UNPARSED_ARGUMENTS})
   endif()
   message(STATUS "Registering ${name} as a pass plugin (static build: ${LLVM_${name_upper}_LINK_INTO_TOOLS})")
 

polly/CMakeLists.txt

@@ -112,6 +112,14 @@ if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
     )
 endif()
 
+# add_llvm_pass_plugin() already declares the option, but we need access to
+# it earlier than that.
+set(link_into_tools_default OFF)
+if (LLVM_TOOL_POLLY_BUILD)
+  set(link_into_tools_default ON)
+endif()
+option(LLVM_POLLY_LINK_INTO_TOOLS "Statically link Polly into tools (if available)" ${link_into_tools_default})
+
 add_definitions( -D_GNU_SOURCE )
 
 add_subdirectory(docs)

polly/cmake/polly_macros.cmake

@@ -39,15 +39,21 @@ macro(add_polly_library name)
     llvm_config(${name} ${LLVM_LINK_COMPONENTS})
   endif( LLVM_LINK_COMPONENTS )
   if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY OR ${name} STREQUAL "LLVMPolly")
+    set(exports)
+    if (LLVM_POLLY_LINK_INTO_TOOLS)
+      set(exports EXPORT LLVMExports)
+    endif()
     install(TARGETS ${name}
       COMPONENT ${name}
-      EXPORT LLVMExports
+      ${exports}
       LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
       ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX})
     add_llvm_install_targets(install-${name}
       COMPONENT ${name})
   endif()
-  set_property(GLOBAL APPEND PROPERTY LLVM_EXPORTS ${name})
+  if (LLVM_POLLY_LINK_INTO_TOOLS)
+    set_property(GLOBAL APPEND PROPERTY LLVM_EXPORTS ${name})
+  endif()
 endmacro(add_polly_library)
 
 macro(add_polly_loadable_module name)