1. Compiler Construction
CS 606
Sohail Aslam
Lecture 1
compiler: intro

2. Course Organization General course information
Homework and project information

3. General Information Instructor Sohail Aslam Lectures 45 Text
Compilers – Principles, Techniques and Tools by Aho, Sethi and Ullman

4. Work Distribution Theory Practice homeworks = 20% exams = 40%
build a compiler = 40%

5. Project Implementation language: subset of java
Generated code: Intel x86 assembly
Implementation language: C++
Six programming assignments

6. Why Take this Course Reason #1: understand compilers and languages
understand the code structure
understand language semantics
understand relation between source code and generated machine code
become a better programmer

7. Why Take this Course Reason #2: nice balance of theory and practice
mathematical models: regular expressions, automata, grammars, graphs
algorithms that use these models

8. Why Take this Course Reason #2: nice balance of theory and practice
Apply theoretical notions to build a real compiler

9. Why Take this Course Reason #3: programming experience
write a large program which manipulates complex data structures
learn more about C++ and Intel x86

10. What are Compilers
Translate information from one representation to another
Usually information = program

11. Examples Typical Compilers: Translators VC, VC++, GCC, JavaC
FORTRAN, Pascal, VB(?)
Translators
Word to PDF
PDF to Postscript

12. In This Course We will study typical compilation:
from programs written in high-level languages to low-level object code and machine code

13. Typical Compilation High-level source code Compiler
Low-level machine code

14. Source Code int expr( int n ) { int d; d = 4*n*n*(n+1)*(n+1);
return d; }

15. Source Code Optimized for human readability
Matches human notions of grammar
Uses named constructs such as variables and procedures

16. Assembly Code _expr: pushl %ebp movl %esp,%ebp movl 8(%ebp),%eax
.globl _expr
_expr:
pushl %ebp
movl %esp,%ebp
subl $24,%esp
movl 8(%ebp),%eax
movl %eax,%edx
leal 0(,%edx,4),%eax
imull 8(%ebp),%edx
incl %eax
imull %eax,%edx
movl 8(%ebp),%eax
incl %eax
movl %edx,-4(%ebp)
movl -4(%ebp),%edx
movl %edx,%eax
jmp L2
.align 4
L2:
leave
ret
compiler: intro

17. Assembly Code Optimized for hardware Consists of machine instructions
Uses registers and unnamed memory locations
Much harder to understand by humans

18. How to Translate Correctness:
the generated machine code must execute precisely the same computation as the source code

19. How to Translate Is there a unique translation? No!
Is there an algorithm for an “ideal translation”? No!

20. How to Translate Translation is a complex process
source language and generated code are very different
Need to structure the translation