First pass at ARMv8 64-bit NEON SIMD support


git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1108 632fc199-4ca6-4c93-a231-07263d6284db
diff --git a/configure.ac b/configure.ac
index c327db5..6234641 100644
--- a/configure.ac
+++ b/configure.ac
@@ -430,7 +430,23 @@
           AC_MSG_ERROR([SIMD support can't be enabled.])
         else
           AC_MSG_WARN([SIMD support can't be enabled.  Performance will suffer.])
+        fi
       fi
+      ;;
+    aarch64*)
+      AC_MSG_RESULT([yes (arm64)])
+      AC_MSG_CHECKING([if the assembler is GNU-compatible and can be used])
+      AC_CHECK_COMPATIBLE_ARM64_ASSEMBLER_IFELSE(
+        [AC_MSG_RESULT([yes])
+         simd_arch=aarch64],
+        [AC_MSG_RESULT([no])
+         with_simd=no])
+      if test "x${with_simd}" = "xno"; then
+        if test "x${require_simd}" = "xyes"; then
+          AC_MSG_ERROR([SIMD support can't be enabled.])
+        else
+          AC_MSG_WARN([SIMD support can't be enabled.  Performance will suffer.])
+        fi
       fi
       ;;
     mipsel*)
@@ -472,6 +488,7 @@
 AM_CONDITIONAL([SIMD_I386], [test "x$simd_arch" = "xi386"])
 AM_CONDITIONAL([SIMD_X86_64], [test "x$simd_arch" = "xx86_64"])
 AM_CONDITIONAL([SIMD_ARM], [test "x$simd_arch" = "xarm"])
+AM_CONDITIONAL([SIMD_ARM_64], [test "x$simd_arch" = "xaarch64"])
 AM_CONDITIONAL([SIMD_MIPSEL], [test "x$simd_arch" = "xmipsel"])
 AM_CONDITIONAL([X86_64], [test "x$host_cpu" = "xx86_64" -o "x$host_cpu" = "xamd64"])
 AM_CONDITIONAL([WITH_TURBOJPEG], [test "x$with_turbojpeg" != "xno"])