Backport of:

https://github.com/php/php-src/commit/8c8679207ae5ada8751288e75b78c928a4d34d1d

diff -u -r ../php-7.1.7/Zend/zend_multiply.h ./Zend/zend_multiply.h
--- ../php-7.1.7/Zend/zend_multiply.h	2017-07-06 11:30:11.000000000 +0200
+++ ./Zend/zend_multiply.h	2017-07-10 00:54:43.550300703 +0200
@@ -53,8 +53,8 @@
 	__asm__("mul %0, %2, %3\n"										\
 		"smulh %1, %2, %3\n"										\
 		"sub %1, %1, %0, asr #63\n"									\
-			: "=X"(__tmpvar), "=X"(usedval)							\
-			: "X"(a), "X"(b));										\
+			: "=&r"(__tmpvar), "=&r"(usedval)						\
+			: "r"(a), "r"(b));										\
 	if (usedval) (dval) = (double) (a) * (double) (b);				\
 	else (lval) = __tmpvar;											\
 } while (0)