Merge pull request #743 from jdemel/fix-64bit-cpu

cmake: Fix 64bit host CPU detection

Author: jdemel

CMakeLists.txt

@@ -10,7 +10,9 @@
 ########################################################################
 # Project setup
 ########################################################################
-cmake_minimum_required(VERSION 3.8)
+# We use `IS_64BIT now: https://cmake.org/cmake/help/latest/command/cmake_host_system_information.html
+cmake_minimum_required(VERSION 3.10)
+
 set(CMAKE_BUILD_TYPE
     ${CMAKE_BUILD_TYPE}
     CACHE STRING "Choose build type: None Debug Release RelWithDebInfo MinSizeRel")

lib/CMakeLists.txt

@@ -255,17 +255,16 @@ endif()
 ########################################################################
 if(NOT CROSSCOMPILE_MULTILIB AND CPU_IS_x86)
     include(CheckTypeSize)
-    check_type_size("void*[8]" SIZEOF_CPU BUILTIN_TYPES_ONLY)
-    if(${SIZEOF_CPU} EQUAL 64)
+    cmake_host_system_information(RESULT ASSUME_64BIT_HOST QUERY IS_64BIT)
+    if(ASSUME_64BIT_HOST)
         overrule_arch(32 "CPU width is 64 bits")
-    endif()
-    if(${SIZEOF_CPU} EQUAL 32)
+    else()
         overrule_arch(64 "CPU width is 32 bits")
     endif()
 
     #MSVC 64 bit does not have MMX, overrule it
     if(MSVC)
-        if(${SIZEOF_CPU} EQUAL 64)
+        if(ASSUME_64BIT_HOST)
             overrule_arch(mmx "No MMX for Win64")
         endif()
         force_arch(sse "Built-in for MSVC > 2013")