From 032e6963fe78d8863252d0ee23dca61d9ca963ee Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Sur=C3=BD?= <ondrej@sury.org>
Date: Tue, 23 Oct 2018 09:27:02 +0200
Subject: [PATCH] Check for yield support on ARM and print helpfull error
 message about -march

---
 configure    | 31 +++++++++++++++++++++++++++++++
 configure.in | 14 ++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/configure b/configure
index 05ed9a2412..efbe6855fc 100755
--- a/configure
+++ b/configure
@@ -13618,6 +13618,37 @@ $as_echo "#define FLEXIBLE_ARRAY_MEMBER /**/" >>confdefs.h
   fi
 
 
+#
+# Check for yield support on ARM processors
+#
+case $host in #(
+  arm*) :
+
+	  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for yield instruction support" >&5
+$as_echo_n "checking for yield instruction support... " >&6; }
+	  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+__asm__ __volatile__ ("yield")
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+else
+  as_fn_error $? "no, try adding -march=native or -march=armv7-a to CFLAGS (see PLATFORM.md for more information)" "$LINENO" 5
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext ;; #(
+  *) :
+     ;;
+esac
+
 for ac_func in sysctlbyname
 do :
   ac_fn_c_check_func "$LINENO" "sysctlbyname" "ac_cv_func_sysctlbyname"
diff --git a/configure.in b/configure.in
index e26918d20d..914e5ae2c1 100644
--- a/configure.in
+++ b/configure.in
@@ -460,6 +460,20 @@ AC_C_INLINE
 AC_C_VOLATILE
 AC_C_FLEXIBLE_ARRAY_MEMBER
 
+#
+# Check for yield support on ARM processors
+#
+AS_CASE([$host],
+	[arm*],[
+	  AC_MSG_CHECKING([for yield instruction support])
+	  AC_COMPILE_IFELSE(
+	    [AC_LANG_PROGRAM(
+	       [[]],
+	       [[__asm__ __volatile__ ("yield")]]
+	     )],
+	    [AC_MSG_RESULT([yes])],
+	    [AC_MSG_ERROR([no, try adding -march=native or -march=armv7-a to CFLAGS (see PLATFORM.md for more information)])])])
+
 AC_CHECK_FUNCS([sysctlbyname])
 
 #