allow external prepare_builtins

In standalone cross builds, libclc can't build a native prepare_builtins.

Hack the CMake to allow it to use an existing binary, which we build in the recipe.

Upstream-Status: Inappropriate [discussion for a proper fix in llvm#149814]
Signed-off-by: Ross Burton <[email protected]>

Author: rossburton

libclc/CMakeLists.txt

@@ -178,17 +178,28 @@ set(LLVM_LINK_COMPONENTS
   IRReader
   Support
 )
+
 if( LIBCLC_STANDALONE_BUILD )
-  add_llvm_executable( prepare_builtins utils/prepare-builtins.cpp )
-  set( prepare_builtins_exe prepare_builtins )
-  set( prepare_builtins_target prepare_builtins )
+  message("cross ${CMAKE_CROSSCOMPILING}")
+  if(CMAKE_CROSSCOMPILING)
+    find_program(PREPARE_BUILTINS prepare_builtins REQUIRED)
+    message("found ${PREPARE_BUILTINS}")
+    set( prepare_builtins_exe ${PREPARE_BUILTINS} )
+  else()
+    add_llvm_executable( prepare_builtins utils/prepare-builtins.cpp )
+    set( prepare_builtins_exe prepare_builtins )
+    set( prepare_builtins_target prepare_builtins )
+    target_compile_definitions( prepare_builtins PRIVATE ${LLVM_VERSION_DEFINE} )
+    # These were not properly reported in early LLVM and we don't need them
+    target_compile_options( prepare_builtins PRIVATE -fno-rtti -fno-exceptions )
+  endif()
 else()
   add_llvm_utility( prepare_builtins utils/prepare-builtins.cpp )
   setup_host_tool( prepare_builtins PREPARE_BUILTINS prepare_builtins_exe prepare_builtins_target )
+  target_compile_definitions( prepare_builtins PRIVATE ${LLVM_VERSION_DEFINE} )
+  # These were not properly reported in early LLVM and we don't need them
+  target_compile_options( prepare_builtins PRIVATE -fno-rtti -fno-exceptions )
 endif()
-target_compile_definitions( prepare_builtins PRIVATE ${LLVM_VERSION_DEFINE} )
-# These were not properly reported in early LLVM and we don't need them
-target_compile_options( prepare_builtins PRIVATE -fno-rtti -fno-exceptions )
 
 # Setup arch devices
 set( r600--_devices cedar cypress barts cayman )