[CMake] Flag recursive cmake invocations for cross-compile

JosephTremoulet · JosephTremoulet · commit e5e75afe8fd4 · 2015-09-09T14:57:06.000Z
Summary: Cross-compilation uses recursive cmake invocations to build native host tools. These recursive invocations only forward a fixed set of variables/options, since the native environment is generally the default. This change adds -DLLVM_TARGET_IS_CROSSCOMPILE_HOST=TRUE to the recursive cmake invocations, so that cmake files can distinguish these recursive invocations from top-level ones, which can explain why expected options are unset. LLILC will use this to avoid trying to generate its build rules in the crosscompile native host target (where it is not needed), which would fail if attempted because LLILC requires a cmake variable passed on the command line, which is not forwarded in the recursive invocation. Reviewers: rnk, beanz Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D12679 llvm-svn: 247151
diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
@@ -560,6 +560,10 @@ include_directories( ${LLVM_INCLUDE_DIR} ${LLVM_MAIN_INCLUDE_DIR})
 if(LLVM_USE_HOST_TOOLS)
   include(CrossCompile)
 endif(LLVM_USE_HOST_TOOLS)
+if(LLVM_TARGET_IS_CROSSCOMPILE_HOST)
+# Dummy use to avoid CMake Wraning: Manually-specified variables were not used
+# (this is a variable that CrossCompile sets on recursive invocations)
+endif()
 
 if(${CMAKE_SYSTEM_NAME} MATCHES "(FreeBSD|DragonFly)")
   # On FreeBSD, /usr/local/* is not used by default. In order to build LLVM
diff --git a/llvm/cmake/modules/CrossCompile.cmake b/llvm/cmake/modules/CrossCompile.cmake
@@ -19,6 +19,7 @@ function(llvm_create_cross_target_internal target_name toochain buildtype)
   add_custom_command(OUTPUT ${LLVM_${target_name}_BUILD}/CMakeCache.txt
     COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}"
         ${CROSS_TOOLCHAIN_FLAGS_${target_name}} ${CMAKE_SOURCE_DIR}
+        -DLLVM_TARGET_IS_CROSSCOMPILE_HOST=TRUE
     WORKING_DIRECTORY ${LLVM_${target_name}_BUILD}
     DEPENDS ${LLVM_${target_name}_BUILD}
     COMMENT "Configuring ${target_name} LLVM...")
@@ -43,6 +44,7 @@ function(llvm_create_cross_target_internal target_name toochain buildtype)
     execute_process(COMMAND ${CMAKE_COMMAND} ${build_type_flags}
         -G "${CMAKE_GENERATOR}" -DLLVM_TARGETS_TO_BUILD=${LLVM_TARGETS_TO_BUILD}
         ${CROSS_TOOLCHAIN_FLAGS_${target_name}} ${CMAKE_SOURCE_DIR}
+        -DLLVM_TARGET_IS_CROSSCOMPILE_HOST=TRUE
       WORKING_DIRECTORY ${LLVM_${target_name}_BUILD} )
   endif(NOT IS_DIRECTORY ${LLVM_${target_name}_BUILD})
 
