Use alternate linker (mold, gold, etc)

qgis · Jul 8, 2022 · db4cf8a · db4cf8a
1 parent 52a34cc
commit db4cf8a
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diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -731,6 +731,10 @@ if(ENABLE_COVERAGE)
   SETUP_TARGET_FOR_COVERAGE(qgis_coverage ctest coverage)
 endif()
 
+if(USE_ALTERNATE_LINKER)
+  include("cmake/modules/linker.cmake")
+endif()
+
 #############################################################
 # platform specific stuff
 if (WITH_CORE)

diff --git a/cmake/modules/linker.cmake b/cmake/modules/linker.cmake
@@ -0,0 +1,42 @@
+macro(set_alternate_linker linker)
+  if( NOT "${USE_ALTERNATE_LINKER}" STREQUAL "${USE_ALTERNATE_LINKER_OLD_CACHED}" )
+    unset(LINKER_EXECUTABLE CACHE)
+  endif()
+  find_program(LINKER_EXECUTABLE ld.${USE_ALTERNATE_LINKER} ${USE_ALTERNATE_LINKER})
+  if(LINKER_EXECUTABLE)
+    if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
+      if( "${CMAKE_CXX_COMPILER_VERSION}" VERSION_GREATER_EQUAL 12.0.0)
+        add_link_options("--ld-path=${LINKER_EXECUTABLE}")
+      else()
+        add_link_options("-fuse-ld=${LINKER_EXECUTABLE}")
+      endif()
+    elseif( "${linker}" STREQUAL "mold" AND
+            "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" AND
+            "${CMAKE_CXX_COMPILER_VERSION}" VERSION_LESS 12.1.0)
+      # GCC before 12.1.0: -fuse-ld does not accept mold as a valid argument,
+      # so you need to use -B option instead.
+      get_filename_component(_dir ${LINKER_EXECUTABLE} DIRECTORY)
+      get_filename_component(_dir ${_dir} DIRECTORY)
+      if( EXISTS "${_dir}/libexec/mold/ld" )
+          add_link_options(-B "${_dir}/libexec/mold")
+      else()
+          message(FATAL_ERROR "Cannot find ${_dir}/libexec/mold/ld")
+      endif()
+    else()
+      add_link_options("-fuse-ld=${USE_ALTERNATE_LINKER}")
+    endif()
+    message(STATUS "Using alternative linker: ${LINKER_EXECUTABLE}")
+  else()
+    message(FATAL_ERROR "Cannot find alternative linker ${USE_ALTERNATE_LINKER}")
+  endif()
+endmacro()
+
+if( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" )
+  set(USE_ALTERNATE_LINKER "" CACHE STRING "Use alternate linker. Leave empty for system default; potential alternatives are 'gold', 'lld', 'bfd', 'mold'")
+  if(NOT "${USE_ALTERNATE_LINKER}" STREQUAL "")
+    set_alternate_linker(${USE_ALTERNATE_LINKER})
+  endif()
+  set(USE_ALTERNATE_LINKER_OLD_CACHED
+      ${USE_ALTERNATE_LINKER}
+      CACHE INTERNAL "Previous value of USE_ALTERNATE_LINKER")
+endif()