added some M1 support

- added arm64 discovery for M1 via CMAKE_SYSTEM_PROCESSOR

detectplatform.cmake

@@ -56,7 +56,11 @@ endif(CMAKE_SYSTEM_NAME STREQUAL Linux)
 
 if(CMAKE_SYSTEM_NAME STREQUAL Darwin)
   set(CLR_CMAKE_PLATFORM_UNIX 1)
-  set(CLR_CMAKE_PLATFORM_UNIX_AMD64 1)
+  if(CMAKE_SYSTEM_PROCESSOR STREQUAL arm64)
+    set(CLR_CMAKE_PLATFORM_UNIX_ARM64 1)
+  else()
+    set(CLR_CMAKE_PLATFORM_UNIX_AMD64 1)
+  endif()
   set(CLR_CMAKE_PLATFORM_DARWIN 1)
   if(CMAKE_VERSION VERSION_LESS "3.4.0")
     set(CMAKE_ASM_COMPILE_OBJECT "${CMAKE_C_COMPILER} <FLAGS> <DEFINES> -o <OBJECT> -c <SOURCE>")

platformdefinitions.cmake

@@ -7,17 +7,21 @@ if (CLR_CMAKE_PLATFORM_ARCH_AMD64)
   add_definitions(-DAMD64)
   add_definitions(-DBIT64=1)          # CoreClr <= 3.x
   add_definitions(-DHOST_64BIT=1)     # CoreClr > 3.x
+  add_definitions(-DHOST_AMD64)
 elseif (CLR_CMAKE_PLATFORM_ARCH_I386)
   add_definitions(-D_X86_)
+  add_definitions(-DHOST_X86)
 elseif (CLR_CMAKE_PLATFORM_ARCH_ARM)
   add_definitions(-D_ARM_)
   add_definitions(-DARM)
+  add_definitions(-DHOST_ARM)
 elseif (CLR_CMAKE_PLATFORM_ARCH_ARM64)
   add_definitions(-D_ARM64_)
   add_definitions(-DARM64)
   add_definitions(-D_WIN64)
   add_definitions(-DBIT64=1)          # CoreClr <= 3.x
   add_definitions(-DHOST_64BIT=1)     # CoreClr > 3.x
+  add_definitions(-DHOST_ARM64)
 else ()
   clr_unknown_arch()
 endif ()
@@ -46,8 +50,12 @@ if (CLR_CMAKE_PLATFORM_UNIX)
   add_definitions(-DPLATFORM_UNIX=1)
 
   if(CLR_CMAKE_PLATFORM_DARWIN)
-    message("Detected OSX x86_64")
-  endif(CLR_CMAKE_PLATFORM_DARWIN)
+    if(CLR_CMAKE_PLATFORM_UNIX_ARM64)
+      message("Detected OSX ARM64")
+    else()
+      message("Detected OSX x86_64")
+    endif()
+  endif()
 
   if(CLR_CMAKE_PLATFORM_FREEBSD)
     message("Detected FreeBSD amd64")