adding another storage type: store_return; when generating a CALL, the generator can check the output value's storetype, and if it is NOT store_return, it needs to STORE_x the return value into the output value.

gmqcc.h

@@ -774,7 +774,8 @@ _MEM_VEC_FUN_FIND(Tself, Twhat, mem)
 enum store_types {
     store_global,
     store_local,  /* local, assignable for now, should get promoted later */
-    store_value   /* unassignable */
+    store_value,  /* unassignable */
+    store_return  /* unassignable, at OFS_RETURN */
 };
 
 typedef struct {

ir.c

@@ -2184,6 +2184,8 @@ tailcall:
         if (instr->opcode >= INSTR_CALL0 && instr->opcode <= INSTR_CALL8) {
             /* Trivial call translation:
              * copy all params to OFS_PARM*
+             * if the output's storetype is not store_return,
+             * add append a STORE instruction!
              *
              * NOTES on how to do it better without much trouble:
              * -) The liferanges!