Code optimization


A compiler can be divided into two phases based on the way they compile:
  1. Analysis phase, also known as front end as shown in diagram below.
  2. Synthesis phase, also known as back end as shown in diagram below.

The code optimization in the synthesis phase is a program transformation technique, which tries to improve the intermediate code by making it consume fewer resources (i.e. CPU, Memory) so that faster-running machine code will result. Compiler optimizing process should meet the following objectives:

  • The optimization must be correct, it must not , in any way, change the meaning of the program.
  • Optimization should increase the speed and performance of the program.
  • The compilation time must be kept reasonable.
  • The optimization process should not delay the overall compiling process.

When to optimize the code?
Optimization of the code is often performed at the end of the development stage since it reduces readability and adds code that is used to increase the performance.
Types of code optimization:
  1. Machine independent optimization
  2. Machine dependent optimization
1.    MACHINE INDEPENDENT OPTIMIZATION: It is done before the target code get generated as the output. It does not involve any CPU registers or memory hierarchy.
2.   MACHINE DEPENDENT OPTIMIZATION: It is done after the target code get generated as the output. I involves the maximum use of CPU registers or memory hierarchy.

unoptimized code
i := j;
until p;
optimized code
i := j;
until p;

Compiler Design covered following topics in Compiler Design.

Python Programming ↓ 👆
Java Programming ↓ 👆
JAVA covered following topics in these notes.
JAVA Programs
Principles of Programming Languages ↓ 👆
Principles of Programming Languages covered following topics in these notes.

Previous years solved papers:
A list of Video lectures References:
  1. Sebesta,”Concept of programming Language”, Pearson Edu 
  2. Louden, “Programming Languages: Principles & Practices” , Cengage Learning 
  3. Tucker, “Programming Languages: Principles and paradigms “, Tata McGraw –Hill. 
  4. E Horowitz, "Programming Languages", 2nd Edition, Addison Wesley

    Computer Organization and Architecture ↓ 👆

    Computer Organization and Architecture covered following topics in these notes.

    1. Structure of desktop computers
    2. Logic gates
    3. Register organization
    4. Bus structure
    5. Addressing modes
    6. Register transfer language
    7. Direct mapping numericals
    8. Register in Assembly Language Programming
    9. Arrays in Assembly Language Programming


    1. William stalling ,“Computer Architecture and Organization” PHI
    2. Morris Mano , “Computer System Organization ”PHI

    Computer Network ↓ 👆
    Computer Network covered following topics in these notes.
    1. Data Link Layer
    2. Framing
    3. Byte count framing method
    4. Flag bytes with byte stuffing framing method
    5. Flag bits with bit stuffing framing method
    6. Physical layer coding violations framing method
    7. Error control in data link layer
    8. Stop and Wait scheme
    9. Sliding Window Protocol
    10. One bit sliding window protocol
    11. A protocol Using Go-Back-N
    12. Selective repeat protocol
    13. Application layer
    1. Andrew S. Tanenbaum, David J. Wetherall, “Computer Networks” Pearson Education.
    2. Douglas E Comer, “Internetworking with TCP/IP Principles, Protocols, And Architecture",Pearson Education
    3. KavehPahlavan, Prashant Krishnamurthy, “Networking Fundamentals”, Wiley Publication.
    4. Ying-Dar Lin, Ren-Hung Hwang, Fred Baker, “Computer Networks: An Open Source Approach”, McGraw Hill.