Spring 2020, Programming Languages Class
- Objective: Building Simple Compiler
- Grammars:
Table 1 < Grammar >
prog ::= word "(" ")" block ;
decls ::= decls decl
| ;
decl ::= vtype words ";" ;
words ::= words "," word
| word ;
vtype ::= int | char
| ;
block ::= "{" decls slist "}"
| ;
slist ::= slist stat
| stat ;
stat ::= IF cond THEN block ELSE block
| WHILE cond block
| word "=" expr ";"
| RETURN expr ";"
| ;
cond ::= expr ">" expr
| expr "==" expr ;
expr ::= term
| term "+" term ;
term ::= fact
| fact "*" fact ;
fact ::= num
| word ;
word ::= ([a-z] | [A-Z])* ;
num ::= [0-9]*
- Instruction Sets:
LD Reg#1, addr(or num) Load var (or num) into the Reg#1
ST Reg#1, addr Store value of Reg#1 into var ADD Reg#1, Reg#2, Reg#3 Reg#1 = Reg#2 + Reg#3
MUL Reg#1, Reg#2, Reg#3 Reg#1 = Reg#2 x Reg#3
LT Reg#1, Reg#2, Reg#3 1 if (Reg#2 < Reg#3), 0 otherwise , store into Reg#1
JUMPF Reg#1 label Jump to label if Reg#1 contains 0
JUMPT Reg#1 label Jump to label if Reg#1 contains Non-0
JUMP label Jump to label without condition