diff --git a/tcg/tcg.h b/tcg/tcg.h
index 231082e..11e9d8a 100644
--- a/tcg/tcg.h
+++ b/tcg/tcg.h
@@ -275,7 +275,8 @@
 #define TCG_CT_CONST  0x02 /* any constant of register size */
 
 typedef struct TCGArgConstraint {
-    uint32_t ct;
+    uint16_t ct;
+    uint8_t alias_index;
     union {
         TCGRegSet regs;
     } u;
@@ -286,6 +287,7 @@
 #define TCG_OPF_BB_END     0x01 /* instruction defines the end of a basic
                                    block */
 #define TCG_OPF_CALL_CLOBBER 0x02 /* instruction clobbers call registers */
+#define TCG_OPF_SIDE_EFFECTS 0x04 /* instruction has side effects */
 
 typedef struct TCGOpDef {
     const char *name;