[runtimes] Fix crosscompiling after a7cad6680b4087eff8994f1f99ac40c661a6621f (D97451)

[tambre]

Summary

It moved the logic for CMake target arguments into llvm_ExternalProject_Add().
No handling was added for CMAKE_CROSSCOMPILING, which has a separate set of compiler_args.
This broke crosscompiling, as now the runtimes builds defaulted to the compiler's default.

I've also added passing of CMAKE_ASM_COMPILER, which was missing before although we were passing the triple for it.

[zero9178]

Sorry for the oversight and thanks for taking a look!

llvm/cmake/modules/LLVMExternalProjectUtils.cmake

236

I think this could potentially cause issues since callers might not specify TARGET_TRIPLE. Would it maybe make sense to move the block from line 214 further down to also affect the cross compiling build?

[tambre]

Move ARG_TARGET_TRIPLE block down to simplify code.

llvm/cmake/modules/LLVMExternalProjectUtils.cmake

236

Not specifying TARGET_TRIPLE probably means non-working crosscompiling for the caller. Only such caller seems to be for the LLVM test suite, which I imagine isn't supported for crosscompiling.

But moving the block down is simpler. Done, thanks!

[zero9178]

LGTM, but maybe wait half a day to a day or so in case anyone more reputable has anything to add.

llvm/cmake/modules/LLVMExternalProjectUtils.cmake

if(ARG_USE_TOOLCHAIN AND NOT CMAKE_CROSSCOMPILING)
     endif()
     list(APPEND ARG_DEPENDS ${TOOLCHAIN_TOOLS})
   endif()
 
   if(ARG_STRIP_TOOL)
     list(APPEND compiler_args -DCMAKE_STRIP=${ARG_STRIP_TOOL})
   endif()
 
-  if (ARG_TARGET_TRIPLE)
-    list(APPEND compiler_args -DCMAKE_C_COMPILER_TARGET=${ARG_TARGET_TRIPLE})
-    list(APPEND compiler_args -DCMAKE_CXX_COMPILER_TARGET=${ARG_TARGET_TRIPLE})
-    list(APPEND compiler_args -DCMAKE_ASM_COMPILER_TARGET=${ARG_TARGET_TRIPLE})
-  endif()
-
   add_custom_command(
     OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${name}-clobber-stamp
     DEPENDS ${ARG_DEPENDS}
     COMMAND ${CMAKE_COMMAND} -E touch ${BINARY_DIR}/CMakeCache.txt
     COMMAND ${CMAKE_COMMAND} -E touch ${STAMP_DIR}/${name}-mkdir
     COMMAND ${CMAKE_COMMAND} -E touch ${CMAKE_CURRENT_BINARY_DIR}/${name}-clobber-stamp
     COMMENT "Clobbering bootstrap build and stamp directories"
     )
 
   add_custom_target(${name}-clobber
     DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/${name}-clobber-stamp)
 
   if(ARG_EXCLUDE_FROM_ALL)
     set(exclude EXCLUDE_FROM_ALL 1)
   endif()
 
   if(CMAKE_SYSROOT)
     set(sysroot_arg -DCMAKE_SYSROOT=${CMAKE_SYSROOT})
   endif()
 
   if(CMAKE_CROSSCOMPILING)
-    set(compiler_args -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
+    set(compiler_args -DCMAKE_ASM_COMPILER=${CMAKE_ASM_COMPILER}
+                      -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
                       -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
                       -DCMAKE_LINKER=${CMAKE_LINKER}
                       -DCMAKE_AR=${CMAKE_AR}
                       -DCMAKE_RANLIB=${CMAKE_RANLIB}
                       -DCMAKE_NM=${CMAKE_NM}
                       -DCMAKE_OBJCOPY=${CMAKE_OBJCOPY}
                       -DCMAKE_OBJDUMP=${CMAKE_OBJDUMP}
                       -DCMAKE_STRIP=${CMAKE_STRIP})
if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
         list(APPEND cmake_args ${${type}_flag})
       endforeach()
     endif()
   else()
     set(llvm_config_path "$<TARGET_FILE:llvm-config>")
     set(cmake_args ${ARG_CMAKE_ARGS})
   endif()
 
+  if(ARG_TARGET_TRIPLE)
+    list(APPEND compiler_args -DCMAKE_C_COMPILER_TARGET=${ARG_TARGET_TRIPLE})
+    list(APPEND compiler_args -DCMAKE_CXX_COMPILER_TARGET=${ARG_TARGET_TRIPLE})
+    list(APPEND compiler_args -DCMAKE_ASM_COMPILER_TARGET=${ARG_TARGET_TRIPLE})
+  endif()
+
   ExternalProject_Add(${name}
     DEPENDS ${ARG_DEPENDS} llvm-config
     ${name}-clobber
     PREFIX ${CMAKE_BINARY_DIR}/projects/${name}
     SOURCE_DIR ${source_dir}
     STAMP_DIR ${STAMP_DIR}
     BINARY_DIR ${BINARY_DIR}
     ${exclude}