[libc-commits] [libc] [libc] [startup] add cmake function to merge separated crt1 objects (PR #75413)

[Schrodinger ZHU Yifan via libc-commits]

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@@ -27,18 +70,24 @@ function(add_startup_object name)
   )
 endfunction()
 
+check_cxx_compiler_flag("-r" LIBC_LINKER_SUPPORTS_RELOCATABLE)
+
+if(NOT LIBC_LINKER_SUPPORTS_RELOCATABLE)
+  message(STATUS "Skipping startup for target architecture ${LIBC_TARGET_ARCHITECTURE}: linker does not support -r")
+  return()
+endif()
+
 if(NOT (EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_ARCHITECTURE}))
   message(STATUS "Skipping startup for target architecture ${LIBC_TARGET_ARCHITECTURE}")
   return()
 endif()
 
 add_subdirectory(${LIBC_TARGET_ARCHITECTURE})
 
-add_startup_object(
+# TODO: factor out crt1 into multiple objects
----------------
SchrodingerZhu wrote:

https://github.com/llvm/llvm-project/pull/75717 is another related change. The purpose of #75717 is to define `LIBC_NAMESPACE::app` symbol regardless it is in the full build or the overlay mode; but the patch also reduced "duplicated" definition of the same symbol.

https://github.com/llvm/llvm-project/pull/75413