[PATCH] D48201: [cmake] Add linker detection for Apple platforms

[Shoaib Meenai via Phabricator via llvm-commits]

smeenai created this revision.
smeenai added reviewers: beanz, phosek.
Herald added subscribers: llvm-commits, mgorny.

LLVM currently assumes that Apple platforms will always use ld64. In the
future, LLD Mach-O might also be supported, so add the beginnings of
linker detection support. ld64 is currently the only detected linker,
since `ld64.lld -v` doesn't yield any useful version output, but we can
add that detection later, and in the meantime it's still useful to have
the ld64 identification.

Switch clang's order file check to use this new detection rather than
just checking for the presence of an ld64 executable.


Repository:
  rL LLVM

https://reviews.llvm.org/D48201

Files:
  clang/tools/driver/CMakeLists.txt
  llvm/cmake/modules/AddLLVM.cmake


Index: llvm/cmake/modules/AddLLVM.cmake
===================================================================
--- llvm/cmake/modules/AddLLVM.cmake
+++ llvm/cmake/modules/AddLLVM.cmake
@@ -147,7 +147,20 @@
   set(LLVM_COMMON_DEPENDS ${LLVM_COMMON_DEPENDS} PARENT_SCOPE)
 endfunction(add_llvm_symbol_exports)
 
-if(NOT WIN32 AND NOT APPLE)
+if(APPLE)
+  execute_process(
+    COMMAND "${CMAKE_LINKER}" -v
+    ERROR_VARIABLE stderr
+    )
+  set(LLVM_LINKER_DETECTED ON)
+  if("${stderr}" MATCHES "PROJECT:ld64")
+    set(LLVM_LINKER_IS_LD64 ON)
+    message(STATUS "Linker detection: ld64")
+  else()
+    set(LLVM_LINKER_DETECTED OFF)
+    message(STATUS "Linker detection: unknown")
+  endif()
+elseif(NOT WIN32)
   # Detect what linker we have here
   if( LLVM_USE_LINKER )
     set(command ${CMAKE_C_COMPILER} -fuse-ld=${LLVM_USE_LINKER} -Wl,--version)
Index: clang/tools/driver/CMakeLists.txt
===================================================================
--- clang/tools/driver/CMakeLists.txt
+++ clang/tools/driver/CMakeLists.txt
@@ -99,10 +99,10 @@
 endif()
 
 if(CLANG_ORDER_FILE AND
-   (LD64_EXECUTABLE OR LLVM_LINKER_IS_GOLD OR LLVM_LINKER_IS_LLD))
+    (LLVM_LINKER_IS_LD64 OR LLVM_LINKER_IS_GOLD OR LLVM_LINKER_IS_LLD))
   include(CheckLinkerFlag)
 
-  if (LD64_EXECUTABLE)
+  if (LLVM_LINKER_IS_LD64)
     set(LINKER_ORDER_FILE_OPTION "-Wl,-order_file,${CLANG_ORDER_FILE}")
   elseif (LLVM_LINKER_IS_GOLD)
     set(LINKER_ORDER_FILE_OPTION "-Wl,--section-ordering-file,${CLANG_ORDER_FILE}")


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