[CMake] Flag recursive cmake invocations for cross-compile

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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@247151 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3518a68ac52d90b12b92af0101d772a3e1d83f8b..dac209765a89802f7faff9f2e2edc77599885670 100644 (file)
--- a/CMakeLists.txt
+++ b/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/cmake/modules/CrossCompile.cmake b/cmake/modules/CrossCompile.cmake
index 76a3078a54405f12cc811142e244d918488c0ca5..c136dfaa612e0e535182313df3a7566fe4f43d31 100644 (file)
--- a/cmake/modules/CrossCompile.cmake
+++ b/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})