Token, SemStack, AST (IR), Spim for Writeln Expressions and Strings

%%t
%%ss
%%dmp -- dump the symbol table - empty at first
beta := 2;
%%dmp
alfa := beta *3;
%%dmp -- symtab has 2 variable names now
writeln ("hi ", beta + 10 * alfa , beta);

simple -i -y -o q0_doitnow.s -l q0_doitnow.list q0_doitnow

in     simple.c
grammar: stmtlist -> lambda
 
Symbol table dump:
SymRoot is NULL => symbol table is empty

Token  : Id
grammar: identifier->Id 
After  : PushId Semstack is:
	 IdEntry (beta)	<+ SemTop
	 StLstEntry
grammar: memref   -> identifier
After  : IdToAddr Semstack is:
	 AddrEntry 	<+ SemTop
	 StLstEntry

Token  : Assignop

Token  : Iconst
grammar: integer_const-> Iconst
After  : PushInt Semstack is:
	 IconstEntry	<+ SemTop
	 AddrEntry 
	 StLstEntry
grammar: primary  -> integer_const
After  : IconstReduce Semstack is:
	 ExprEntry 	<+ SemTop
	 AddrEntry 
	 StLstEntry
grammar: fact     -> primary
grammar: term     -> fact

Token  : Termsym
grammar: expr     -> term
grammar: assignstmt->memeref Assignop expr
After  : Assign Semstack is:
	 StmtEntry 	<+ SemTop
	 StLstEntry
grammar: stmt     -> assignstmt Termsym
grammar: stmtlist -> stmtlist stmt
After  : MergeStmts Semstack is:
	 StLstEntry	<+ SemTop
 
Symbol table dump:
  beta

Token  : Id
grammar: identifier->Id 
After  : PushId Semstack is:
	 IdEntry (alfa)	<+ SemTop
	 StLstEntry
grammar: memref   -> identifier
After  : IdToAddr Semstack is:
	 AddrEntry 	<+ SemTop
	 StLstEntry

Token  : Assignop

Token  : Id
grammar: identifier->Id 
After  : PushId Semstack is:
	 IdEntry (beta)	<+ SemTop
	 AddrEntry 
	 StLstEntry
grammar: memref   -> identifier
After  : IdToAddr Semstack is:
	 AddrEntry 	<+ SemTop
	 AddrEntry 
	 StLstEntry
grammar: primary  -> memref
After  : AddrToPrimary Semstack is:
	 ExprEntry 	<+ SemTop
	 AddrEntry 
	 StLstEntry
grammar: fact     -> primary
grammar: term     -> fact

Token  : Mpysym
grammar: multop   -> Mpysym
After  : Operator  Semstack is:
	 OperEntry 	<+ SemTop
	 ExprEntry 
	 AddrEntry 
	 StLstEntry

Token  : Iconst
grammar: integer_const-> Iconst
After  : PushInt Semstack is:
	 IconstEntry	<+ SemTop
	 OperEntry 
	 ExprEntry 
	 AddrEntry 
	 StLstEntry
grammar: primary  -> integer_const
After  : IconstReduce Semstack is:
	 ExprEntry 	<+ SemTop
	 OperEntry 
	 ExprEntry 
	 AddrEntry 
	 StLstEntry
grammar: fact     -> primary
grammar: term     -> term multop fact
After  : DoArithOp Semstack is:
	 ExprEntry 	<+ SemTop
	 AddrEntry 
	 StLstEntry

Token  : Termsym
grammar: expr     -> term
grammar: assignstmt->memeref Assignop expr
After  : Assign Semstack is:
	 StmtEntry 	<+ SemTop
	 StLstEntry
grammar: stmt     -> assignstmt Termsym
grammar: stmtlist -> stmtlist stmt
After  : MergeStmts Semstack is:
	 StLstEntry	<+ SemTop
 
Symbol table dump:
  alfa
  beta

Token  : Writeln

Token  : Lparen

Token  : StrConst
grammar: actparam  -> StrConst
After  : PushString Semstack is:
	 StrEntry (hi )	<+ SemTop
	 StLstEntry
After  : CreateActParam Semstack is:
	 ParmEntry 	<+ SemTop
	 StLstEntry
grammar: actparamlist->actparam

Token  : Commasym

Token  : Id
grammar: identifier->Id 
After  : PushId Semstack is:
	 IdEntry (beta)	<+ SemTop
	 ParmEntry 
	 StLstEntry
grammar: memref   -> identifier
After  : IdToAddr Semstack is:
	 AddrEntry 	<+ SemTop
	 ParmEntry 
	 StLstEntry
grammar: primary  -> memref
After  : AddrToPrimary Semstack is:
	 ExprEntry 	<+ SemTop
	 ParmEntry 
	 StLstEntry
grammar: fact     -> primary
grammar: term     -> fact

Token  : Plussym
grammar: expr     -> term
grammar: addop    -> Plussym
After  : Operator  Semstack is:
	 OperEntry 	<+ SemTop
	 ExprEntry 
	 ParmEntry 
	 StLstEntry

Token  : Iconst
grammar: integer_const-> Iconst
After  : PushInt Semstack is:
	 IconstEntry	<+ SemTop
	 OperEntry 
	 ExprEntry 
	 ParmEntry 
	 StLstEntry
grammar: primary  -> integer_const
After  : IconstReduce Semstack is:
	 ExprEntry 	<+ SemTop
	 OperEntry 
	 ExprEntry 
	 ParmEntry 
	 StLstEntry
grammar: fact     -> primary
grammar: term     -> fact

Token  : Mpysym
grammar: multop   -> Mpysym
After  : Operator  Semstack is:
	 OperEntry 	<+ SemTop
	 ExprEntry 
	 OperEntry 
	 ExprEntry 
	 ParmEntry 
	 StLstEntry

Token  : Id
grammar: identifier->Id 
After  : PushId Semstack is:
	 IdEntry (alfa)	<+ SemTop
	 OperEntry 
	 ExprEntry 
	 OperEntry 
	 ExprEntry 
	 ParmEntry 
	 StLstEntry
grammar: memref   -> identifier
After  : IdToAddr Semstack is:
	 AddrEntry 	<+ SemTop
	 OperEntry 
	 ExprEntry 
	 OperEntry 
	 ExprEntry 
	 ParmEntry 
	 StLstEntry
grammar: primary  -> memref
After  : AddrToPrimary Semstack is:
	 ExprEntry 	<+ SemTop
	 OperEntry 
	 ExprEntry 
	 OperEntry 
	 ExprEntry 
	 ParmEntry 
	 StLstEntry
grammar: fact     -> primary
grammar: term     -> term multop fact
After  : DoArithOp Semstack is:
	 ExprEntry 	<+ SemTop
	 OperEntry 
	 ExprEntry 
	 ParmEntry 
	 StLstEntry

Token  : Commasym
grammar: expr     -> expr addop term
After  : DoArithOp Semstack is:
	 ExprEntry 	<+ SemTop
	 ParmEntry 
	 StLstEntry
grammar: actparam  -> expr
After  : CreateActParam Semstack is:
	 ParmEntry 	<+ SemTop
	 ParmEntry 
	 StLstEntry
grammar: actparamlist->actparamlist Commasym actparam
After  : MergeActParam Semstack is:
	 ParmEntry 	<+ SemTop
	 StLstEntry

Token  : Id
grammar: identifier->Id 
After  : PushId Semstack is:
	 IdEntry (beta)	<+ SemTop
	 ParmEntry 
	 StLstEntry
grammar: memref   -> identifier
After  : IdToAddr Semstack is:
	 AddrEntry 	<+ SemTop
	 ParmEntry 
	 StLstEntry
grammar: primary  -> memref
After  : AddrToPrimary Semstack is:
	 ExprEntry 	<+ SemTop
	 ParmEntry 
	 StLstEntry
grammar: fact     -> primary
grammar: term     -> fact

Token  : Rparen
grammar: expr     -> term
grammar: actparam  -> expr
After  : CreateActParam Semstack is:
	 ParmEntry 	<+ SemTop
	 ParmEntry 
	 StLstEntry
grammar: actparamlist->actparamlist Commasym actparam
After  : MergeActParam Semstack is:
	 ParmEntry 	<+ SemTop
	 StLstEntry
grammar: writestmt-> Writeln Lparen actparamlist Rparen
After  : Call Semstack is:
	 StmtEntry 	<+ SemTop
	 StLstEntry

Token  : Termsym
grammar: stmt     -> writestmt Termsym
grammar: stmtlist -> stmtlist stmt
After  : MergeStmts Semstack is:
	 StLstEntry	<+ SemTop
grammar: program  -> stmtlist
After  : Done Semstack is:
		EMPTY

Intermediate Representation (AST)
 
Intermediate Representation - the Abstract Syntax Tree
   Statements
      Assign
         beta
            gets
         Immediate Value 2
      Assign
         alfa
            gets
            beta
         multiply
            Immediate Value 3
      Writeln
         parameters
            hi 
               beta
            add
                  Immediate Value 10
               multiply
                  alfa
            beta


From codegen.c - DisplayRegs() marks used registers

Register: 0 1 2 3 4 5 6 7 8 9 
          - - - - - - - - - - 
Used = x:                    

COMPILATION COMPLETE
out    simple.c

Generated SPIM code
# Register Usage:
#     $s0 for global variables
#
        .text
        .globl main
 main:
        la      $t9, CONST
        la      $s0, GVARS
#
# Start Code
#
# Generate Assignment Statement
        li      $t0,2
        sw      $t0,4($s0)
#
# Generate Assignment Statement
        lw      $t0,4($s0)
        mul     $t0,$t0,3
        sw      $t0,0($s0)
#
# Generate Writeln statement
        la      $a0, S1
        li      $v0, 4
        syscall
        lw      $t0,0($s0)
        mul     $t0,$t0,10
        lw      $t1,4($s0)
        add     $t0,$t0,$t1
        li      $v0, 1
        move    $a0,$t0
        syscall
        li      $v0, 1
        lw      $a0,4($s0)
        syscall
        la      $a0, S0
        li      $v0, 4
        syscall

#
# Halt execution
        li      $v0 10
        syscall

#
# Finish up by writing out constants
        .word 0
CONST:          #Constant storage area
        .data
S0:     .asciiz "\n"
        .data
S1:     .asciiz "hi "
#
# Reserve space for global variables
        .word 0
GVARS:          # space for Global Variables
        .data
_alfa:  .word 0 # Offset at 0
        .data
_beta:  .word 0 # Offset at 4
        .data
Temp_Wr:
        .word 0 #just for alignment of write(exprtree)

Execute with spim
SPIM Version 6.2 of January 11, 1999
Copyright 1990-1998 by James R. Larus (larus@cs.wisc.edu).
All Rights Reserved.
See the file README for a full copyright notice.
Loaded: /opt/spim/bin/trap.handler
hi 622