8248238: Implementation: JEP 388: Windows AArch64 Support

Co-authored-by: Monica Beckwith <mbeckwit@openjdk.org>
Co-authored-by: Ludovic Henry <luhenry@openjdk.org>
Co-authored-by: Bernhard Urban-Forster <burban@openjdk.org>
Reviewed-by: dholmes, cjplummer, aph, ihse

Author: 3 people

make/autoconf/basic.m4

@@ -117,6 +117,16 @@ AC_DEFUN([BASIC_EVAL_DEVKIT_VARIABLE],
   fi
 ])
 
+###############################################################################
+# Evaluates platform specific overrides for build devkit variables.
+# $1: Name of variable
+AC_DEFUN([BASIC_EVAL_BUILD_DEVKIT_VARIABLE],
+[
+  if test "x[$]$1" = x; then
+    eval $1="\${$1_${OPENJDK_BUILD_CPU}}"
+  fi
+])
+
 ###############################################################################
 AC_DEFUN_ONCE([BASIC_SETUP_DEVKIT],
 [

make/autoconf/flags-cflags.m4

@@ -666,7 +666,9 @@ AC_DEFUN([FLAGS_SETUP_CFLAGS_CPU_DEP],
 
   # toolchain dependend, per-cpu
   if test "x$TOOLCHAIN_TYPE" = xmicrosoft; then
-    if test "x$FLAGS_CPU" = xx86_64; then
+    if test "x$FLAGS_CPU" = xaarch64; then
+      $1_DEFINES_CPU_JDK="${$1_DEFINES_CPU_JDK} -D_ARM64_ -Darm64"
+    elif test "x$FLAGS_CPU" = xx86_64; then
       $1_DEFINES_CPU_JDK="${$1_DEFINES_CPU_JDK} -D_AMD64_ -Damd64"
     else
       $1_DEFINES_CPU_JDK="${$1_DEFINES_CPU_JDK} -D_X86_ -Dx86"