Merge pull request swiftlang#812 from hjyamauchi/arm64

Support Windows ARM64 builds

Author: compnerd

cmake/modules/DispatchWindowsSupport.cmake

@@ -6,7 +6,7 @@ function(dispatch_windows_arch_spelling arch var)
     set(${var} x64 PARENT_SCOPE)
   elseif(${arch} STREQUAL armv7)
     set(${var} arm PARENT_SCOPE)
-  elseif(${arch} STREQUAL aarch64)
+  elseif(${arch} STREQUAL aarch64 OR ${arch} STREQUAL ARM64)
     set(${var} arm64 PARENT_SCOPE)
   else()
     message(FATAL_ERROR "do not know MSVC spelling for ARCH: `${arch}`")

cmake/modules/SwiftSupport.cmake

@@ -9,7 +9,7 @@
 function(get_swift_host_arch result_var_name)
   if("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "x86_64")
     set("${result_var_name}" "x86_64" PARENT_SCOPE)
-  elseif ("${CMAKE_SYSTEM_PROCESSOR}" MATCHES "AArch64|aarch64|arm64")
+  elseif ("${CMAKE_SYSTEM_PROCESSOR}" MATCHES "AArch64|aarch64|arm64|ARM64")
     if(CMAKE_SYSTEM_NAME MATCHES Darwin)
       set("${result_var_name}" "arm64" PARENT_SCOPE)
     else()