#ifndef ALIGN_6
#define ALIGN_6 .align 64
+
+// ffreep %st(0).
+// Because Clang didn't support ffreep, we directly use the opcode.
+// Please check out http://www.sandpile.org/x86/opc_fpu.htm
+#ifndef ffreep
+#define ffreep .byte 0xdf, 0xc0 #
+#endif
#endif