$9.-[$Stack mechanism and code generation$](11$ points$).$ Consider the program described below

and give the generated code for the statements at $1,2,$ and $3.$ Procedures are called as shown

below.

BIGSUB calls SUB$2$

SUB$2$ calls SUB$3$

SUB$3$ calls SUB$1$

$($Assume the ARs have SL$,$ DL$,$ and RA$.$ If errors occur, indicate where it is detected and what is

the cause of the error.

procedure BIGSUB;

var A$,$ B$,$ C : integer;

procedure SUB$1$;

var A$,$ K : integer;

begin $\{$ SUB$1\}$

B :$=$ C $+$ A; $<-----------------------1$

end; $\{$ SUB$1\}$

procedure SUB$2($X : integer$)$;

var B$,$ F$,$ E : integer;

procedure SUB$3$;

var C$,$ K$,$ E : integer;

begin $\{$ SUB$3\}$

SUB$1$;

K :$=$ B $*$ E; $<--------------------2$

end; $\{$ SUB$3\}$

begin $\{$ SUB$2\}$

SUB$3$;

K :$=$ E $+$ A; $<-----------------------3$

end; $\{$ SUB$2\}$

begin $\{$ BIGSUB $\}$

SUB$2(9)$;

end; $\{$ BIGSUB $\}$