CMake: Avoid erroneous cross-compilation warnings

Co-authored-by: Matthias Diener <[email protected]>

Author: evan-charmworks

CMakeLists.txt

@@ -86,14 +86,40 @@ set(NETWORK "netlrts" CACHE STRING "Target network layer, can be one of mpi,mult
 set(TARGET "charm++" CACHE STRING "Target build type, can be one of charm++,AMPI,LIBS,charm4py,ChaNGa,everylb,all-test")
 set(ARCH "" CACHE STRING "Target architecture, can be one of i386,x86_64,arm7,arm8,ppc64le") # By default, detect arch we are running on.
 
-if(NOT ARCH STREQUAL CMAKE_HOST_SYSTEM_PROCESSOR)
-  if (ARCH STREQUAL "i386" AND CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL "x86_64")
-    message(WARNING "Attempting to cross-compile from ${CMAKE_HOST_SYSTEM_PROCESSOR} to ${ARCH}. This is only supported for x86_64 -> i386 currently.")
+function(charm_determine_arch output input)
+  if(input STREQUAL "x86_64" OR input STREQUAL "AMD64")
+    set(retval "x86_64")
+  elseif(input STREQUAL "i386" OR input STREQUAL "i686")
+    set(retval "i386")
+  elseif(input STREQUAL "powerpc" OR input MATCHES "^ppc")
+    set(retval "ppc64le")
+  elseif(input MATCHES "armv6" OR input MATCHES "armv7")
+    set(retval "arm7")
+  elseif(input MATCHES "aarch64" OR input MATCHES "arm64")
+    set(retval "arm8")
+  else()
+    set(retval ${input})
+  endif()
+
+  set(${output} ${retval} PARENT_SCOPE)
+endfunction()
+
+if(ARCH)
+  set(CHARM_CPU ${ARCH})
+else()
+  charm_determine_arch(CHARM_CPU ${CMAKE_SYSTEM_PROCESSOR})
+endif()
+
+charm_determine_arch(CHARM_HOST_CPU ${CMAKE_HOST_SYSTEM_PROCESSOR})
+
+if(NOT CHARM_CPU STREQUAL CHARM_HOST_CPU)
+  if (CHARM_CPU STREQUAL "i386" AND CHARM_HOST_CPU STREQUAL "x86_64")
+    message(STATUS "Attempting to cross-compile from ${CHARM_HOST_CPU} to ${CHARM_CPU}.")
     set(CMAKE_C_FLAGS -m32)
     set(CMAKE_CXX_FLAGS -m32)
     set(CMAKE_Fortran_FLAGS -m32)
   else()
-    message(WARNING "Cross-compiling from  ${CMAKE_HOST_SYSTEM_PROCESSOR} to ${ARCH} is not supported currently.")
+    message(WARNING "Cross-compiling from ${CHARM_HOST_CPU} to ${CHARM_CPU} is not supported currently.")
   endif()
 endif()
 
@@ -341,24 +367,11 @@ else()
 endif()
 
 set(CMK_POWER7 0)
-if(ARCH)
-  set(CHARM_CPU ${ARCH})
-elseif(CMAKE_SYSTEM_PROCESSOR STREQUAL "x86_64" OR CMAKE_SYSTEM_PROCESSOR STREQUAL "AMD64")
-  set(CHARM_CPU "x86_64")
-elseif(CMAKE_SYSTEM_PROCESSOR STREQUAL "i386" OR CMAKE_SYSTEM_PROCESSOR STREQUAL "i686")
-  set(CHARM_CPU "i386")
-elseif(CMAKE_SYSTEM_PROCESSOR STREQUAL "powerpc" OR CMAKE_SYSTEM_PROCESSOR MATCHES "^ppc")
-  set(CHARM_CPU "ppc64le")
+if(CHARM_CPU STREQUAL "ppc64le")
   execute_process(COMMAND grep f Makefile RESULT_VARIABLE isppc7 OUTPUT_QUIET ERROR_QUIET)
   if(${isppc7})
     set(CMK_POWER7 1)
   endif()
-elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "armv6" OR CMAKE_SYSTEM_PROCESSOR MATCHES "armv7")
-  set(CHARM_CPU "arm7")
-elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "aarch64" OR CMAKE_SYSTEM_PROCESSOR MATCHES "arm64")
-  set(CHARM_CPU "arm8")
-else()
-  message(FATAL_ERROR "Unsupported CPU ${CMAKE_SYSTEM_PROCESSOR}.")
 endif()
 
 # Adjust version number so it can be tested by numerical comparisons, e.g. 6.10.1 -> 61001:
@@ -566,6 +579,10 @@ set(VDIR ${CHARM_PLATFORM})
 set(CMK_VDIR ${VDIR})
 set(CMK_GDIR ${GDIR})
 
+if(NOT EXISTS ${CMAKE_SOURCE_DIR}/src/arch/${VDIR}/)
+  message(FATAL_ERROR "Unsupported platform ${VDIR}.")
+endif()
+
 configure_file(src/arch/common/cc-bluegene.sh                include/ COPYONLY)
 configure_file(src/arch/common/cc-clang.sh                   include/ COPYONLY)
 configure_file(src/arch/common/cc-clang.h                    include/ COPYONLY)