Add LTO and gold plugin to the CMake build. Linux-only, support for

other systems pending.

PR9456.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127466 91177308-0d34-0410-b5e6-96231b3b80d8

tools/gold/CMakeLists.txt

@@ -0,0 +1,37 @@
+set(LLVM_BINUTILS_INCDIR "/usr/include" CACHE PATH
+  "PATH to binutils/include containing plugin-api.h for gold plugin.")
+
+if( NOT EXISTS "${LLVM_BINUTILS_INCDIR}/plugin-api.h" )
+  message(STATUS "plugin-api.h not found. gold plugin excluded from the build.")
+else()
+  include_directories( ${LLVM_BINUTILS_INCDIR} )
+
+  # Because off_t is used in the public API, the largefile parts are required for
+  # ABI compatibility.
+  add_definitions( -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 )
+
+  set(LLVM_LINK_COMPONENTS support)
+
+  add_llvm_loadable_module(LLVMgold
+    gold-plugin.cpp
+    )
+
+  # Makefile.rules contains a special cases for OpenBSD, Darwin and
+  # Windows. We restrict ourselves to Linux for the time being.
+  set(srcexp ${CMAKE_CURRENT_SOURCE_DIR}/gold.exports)
+  add_custom_command(OUTPUT exportsfile
+    COMMAND echo "{" > exportsfile
+    COMMAND grep -q "\\<" ${srcexp} && echo "  global:" >> exportsfile || :
+    COMMAND sed -e "s/\$\$/;/" -e "s/^/    /" < ${srcexp} >> exportsfile
+    COMMAND echo "  local: *;" >> exportsfile
+    COMMAND echo "};" >> exportsfile
+    DEPENDS ${srcexp}
+    VERBATIM
+    COMMENT "Creating export file for gold plugin")
+  add_custom_target(gold_exports DEPENDS exportsfile)
+  set_property(DIRECTORY APPEND
+    PROPERTY ADDITIONAL_MAKE_CLEAN_FILES exportsfile)
+
+  target_link_libraries(LLVMgold LTO -Wl,--version-script,exportsfile)
+  add_dependencies(LLVMgold gold_exports)
+endif()