Merge pull request #5005 from gottesmm/specify_lto_object_path_on_macos

Specify lto object path on macos

Author: gottesmm

cmake/modules/AddSwift.cmake

@@ -250,13 +250,14 @@ function(_add_variant_swift_compile_flags
 endfunction()
 
 function(_add_variant_link_flags)
-  set(oneValueArgs SDK ARCH BUILD_TYPE ENABLE_ASSERTIONS ANALYZE_CODE_COVERAGE DEPLOYMENT_VERSION_IOS RESULT_VAR_NAME ENABLE_LTO)
+  set(oneValueArgs SDK ARCH BUILD_TYPE ENABLE_ASSERTIONS ANALYZE_CODE_COVERAGE
+  DEPLOYMENT_VERSION_IOS RESULT_VAR_NAME ENABLE_LTO LTO_OBJECT_NAME)
   cmake_parse_arguments(LFLAGS
     ""
     "${oneValueArgs}"
     ""
     ${ARGN})
-  
+
   if("${LFLAGS_SDK}" STREQUAL "")
     message(FATAL_ERROR "Should specify an SDK")
   endif()
@@ -294,6 +295,19 @@ function(_add_variant_link_flags)
         "${SWIFT_ANDROID_NDK_PATH}/sources/cxx-stl/llvm-libc++/libs/armeabi-v7a/libc++_shared.so")
   else()
     list(APPEND result "-lobjc")
+
+    # If lto is enabled, we need to add the object path flag so that the LTO code
+    # generator leaves the intermediate object file in a place where it will not
+    # be touched. The reason why this must be done is that on OS X, debug info is
+    # left in object files. So if the object file is removed when we go to
+    # generate a dsym, the debug info is gone.
+    if (LFLAGS_ENABLE_LTO)
+      precondition(LFLAGS_LTO_OBJECT_NAME
+        MESSAGE "Should specify a unique name for the lto object")
+      set(lto_object_dir ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR})
+      set(lto_object ${lto_object_dir}/${LFLAGS_LTO_OBJECT_NAME}-lto.o)
+        list(APPEND result "-Wl,-object_path_lto,${lto_object}")
+      endif()
   endif()
 
   if(NOT "${SWIFT_${LFLAGS_SDK}_ICU_UC}" STREQUAL "")
@@ -932,6 +946,7 @@ function(_add_swift_library_single target name)
     ENABLE_ASSERTIONS "${enable_assertions}"
     ANALYZE_CODE_COVERAGE "${analyze_code_coverage}"
     ENABLE_LTO "${lto_type}"
+    LTO_OBJECT_NAME "${target}-${SWIFTLIB_SINGLE_SDK}-${SWIFTLIB_SINGLE_ARCHITECTURE}"
     DEPLOYMENT_VERSION_IOS "${SWIFTLIB_DEPLOYMENT_VERSION_IOS}"
     RESULT_VAR_NAME link_flags
       )
@@ -1643,6 +1658,7 @@ function(_add_swift_executable_single name)
     BUILD_TYPE "${CMAKE_BUILD_TYPE}"
     ENABLE_ASSERTIONS "${LLVM_ENABLE_ASSERTIONS}"
     ENABLE_LTO "${SWIFT_TOOLS_ENABLE_LTO}"
+    LTO_OBJECT_NAME "${name}-${SWIFTEXE_SINGLE_SDK}-${SWIFTEXE_SINGLE_ARCHITECTURE}"
     ANALYZE_CODE_COVERAGE "${SWIFT_ANALYZE_CODE_COVERAGE}"
     RESULT_VAR_NAME link_flags)
 

tools/SourceKit/CMakeLists.txt

@@ -83,6 +83,7 @@ function(add_sourcekit_default_compiler_flags target)
     BUILD_TYPE "${build_type}"
     ENABLE_ASSERTIONS "${enable_assertions}"
     ENABLE_LTO "${SWIFT_TOOLS_ENABLE_LTO}"
+    LTO_OBJECT_NAME "${target}-${sdk}-${arch}"
     ANALYZE_CODE_COVERAGE "${analyze_code_coverage}"
     RESULT_VAR_NAME link_flags)