1. CC410: System Programming
Dr. Manal Helal – Fall 2014 – Lecture 13– Compilers 2

2. Chapter 5 - Compilers Optimization (optional) Source program
Intermediate
code
generator
(semantic
analyzer)
Code
generator
Lexical
analizer
Syntax
analizer
Intermediate
code
Lexical units
(Tokens)
Machine
language
Parse trees
Computer
Symbol table

3. Code Generation
Add S(id) to LIST and LISTCOUNT++

4. Code Generation (cont’d.)

5. Code Generation (cont’d.)

6. Code Generation (cont’d.)
Save to Register A
1. <term>2 already in Register A, or
2. <factor> already in Register A, or
3. <term>2 and <factor>both are not in Register A

7. Code Generation (cont’d.)
Node Specifier S(<term>1)
save to rA

9. Code Generation (cont’d.)

10. Code Generation (cont’d.) 9 and 10
S(<exp>) := S(<term>)
S(<exp>) <> rA =S(MEAN)

11. Code Generation (cont’d.) 10

12. Code Generation (cont’d.) 10
S(<exp>2) <> rA
Call GETA(<exp>2)
Generate [SUB S(MEAN)=T2]
S(<exp>1) := rA
REGA := <exp>1

13. Code Generation (cont’d.) 11
S(<term>) := S(SUMSQ)
S(<term>) <> rA
S(<term>) := S(MEAN)

14. Code Generation (cont’d.) 11
S(<term>2) <> rA
S(<factor>) <> rA
Call GETA(MEAN)
Generate [MUL MEAN]
S(MEAN) := rA
REGA:= MEAN

15. Code Generation (cont’d.) 11
S(<term>2) <> rA
Call GETA(SUMSQ)
Generate [DIV #100]
S(<term>1) := rA
REGA := <term>1

16. Code Generation (cont’d.) 12
S(<factor>) := S(SUMSQ)
S(<factor>) := S(MEAN)
S(<factor>) := S(#100)

17. Code Generation (cont’d.)
REGA <> NULL = SUMSQ
S(MEAN) <> rA = S(SUMSQ)
Generate [STA T1]
S(SUMSQ) = T1
Generate [LDA MEAN]
S(MEAN) := rA
REGA := MEAN
REGA = NULL
Generate [LDA SUMSQ]
S(SUMSQ) := rA
REGA := SUMSQ
REGA <> NULL = MEAN
S(SUMSQ) <> rA = S(MEAN)
Generate [STA T2]
S(MEAN) = T2
Generate [LDA S(SUMSQ)=T1]
S(SUMSQ) := rA
REGA := SUMSQ

18. Code Generation (cont’d.)

19. Code Generation (cont’d.) 1, 2, and 3

20. Code Generation (cont’d.) 4, 5, and 7

21. 8, 14, 15

22. Code Generation (cont’d.) 16 and 17

23. Code Generation (cont’d.)

24. Code Generation (cont’d.)