[PATCH] D15133: [CMake] Add option LLVM_EXTERNALIZE_DEBUGINFO

[Justin Bogner via llvm-commits]

Chris Bieneman <beanz at apple.com> writes:
> beanz updated this revision to Diff 41660.
> beanz added a comment.
>
> For LTO builds, dsymutil doesn't need to run against the intermediate
> object, we just need to make sure it sticks around.
>
>
> http://reviews.llvm.org/D15133
>
> Files:
>   CMakeLists.txt
>   cmake/modules/AddLLVM.cmake
>
> Index: cmake/modules/AddLLVM.cmake
> ===================================================================
> --- cmake/modules/AddLLVM.cmake
> +++ cmake/modules/AddLLVM.cmake
> @@ -512,6 +512,10 @@
>        add_dependencies(${objlib} ${LLVM_COMMON_DEPENDS})
>      endforeach()
>    endif()
> +
> +  if(ARG_SHARED OR ARG_MODULE)
> +    llvm_externalize_darwin_debuginfo(${name})
> +  endif()
>  endfunction()
>  
>  macro(add_llvm_library name)
> @@ -655,6 +659,8 @@
>    if( LLVM_COMMON_DEPENDS )
>      add_dependencies( ${name} ${LLVM_COMMON_DEPENDS} )
>    endif( LLVM_COMMON_DEPENDS )
> +
> +  llvm_externalize_darwin_debuginfo(${name})
>  endmacro(add_llvm_executable name)
>  
>  function(export_executable_symbols target)
> @@ -1168,3 +1174,18 @@
>      endif()
>    endif()
>  endfunction()
> +
> +function(llvm_externalize_darwin_debuginfo name)
> +  if(APPLE AND LLVM_EXTERNALIZE_DEBUGINFO)

Better to early exit `if (NOT LLVM_EXTERNALIZE_DEBUGINFO)` before
checking APPLE.

I'd also prefer if we error'd out on non-darwin for now. I don't like
silently ignored flags, and if someone wants to implement it later this
is the obvious place to do split-dwarf on linux-like platforms. Then
presumably the "_darwin" isn't necessary in the function name.

> +    if(CMAKE_CXX_FLAGS MATCHES "-flto"
> +      OR CMAKE_CXX_FLAGS_${uppercase_CMAKE_BUILD_TYPE} MATCHES "-flto")
> +
> +      set(lto_object ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}/${name}.o)

Can this collide with anything? Maybe ${name}.lto.o is safer?

Other than those couple of points, this LGTM.

> +      set_target_properties(${name} PROPERTIES
> +        LINK_FLAGS "-Wl,-object_path_lto -Wl,${lto_object}")
> +    endif()
> +    add_custom_command(TARGET ${name} POST_BUILD
> +      COMMAND xcrun dsymutil $<TARGET_FILE:${name}>
> +      COMMAND xcrun strip -Sl $<TARGET_FILE:${name}>)
> +  endif()
> +endfunction()
> Index: CMakeLists.txt
> ===================================================================
> --- CMakeLists.txt
> +++ CMakeLists.txt
> @@ -301,6 +301,9 @@
>  option(LLVM_USE_OPROFILE
>    "Use opagent JIT interface to inform OProfile about JIT code" OFF)
>  
> +option(LLVM_EXTERNALIZE_DEBUGINFO
> +  "Generate dSYM files and strip executables and libraries (Darwin Only)" OFF)
> +
>  # If enabled, verify we are on a platform that supports oprofile.
>  if( LLVM_USE_OPROFILE )
>    if( NOT CMAKE_SYSTEM_NAME MATCHES "Linux" )
>
>