Compiling a Program

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Compiling a Program

You need to know the process a piece of code undergoes when it is compiled by a program.

Compiling a program

When code is compiled through a compiler, it has to go through 4 stages before it is ready to run.

Stages of compilation

Those stages are:
1. Lexical analysis.
2. Syntax analysis.
3. Code generation.
4. Code optimisation.

Lexical Analysis

Lexical analysis is the first stage a compiled language goes through to compile code.

White space

Firstly, white space is removed from the code.
This is the white space that is present to help humans read the code.
The compiler doesn’t need the white space so it is removed.

Tokens

The compiler will then look through the code and create tokens out of the keywords and operators it finds (lexemes).
A token is a string that is recognised by the computer.
- For example, the number 8 might be assigned the token 'number:8'.
Any comments are ignored by the compiler.

Symbol table

These tokens are assembled into a symbol table ready for the next step of the compiling process.

Syntax Analysis, Code Generation & Optimisation

When code is compiled through a compiler, it has to go through 4 stages before it is ready to run.

Step 2: syntax analysis

During syntax analysis, the tokenised code from the lexical analysis is compared to the rules of the programming language.
If a section or part of the code is found to not fit with these rules, an error is generated with details of what and where it is.
It will continue to perform syntax analysis of all of the code and generate more errors if found.
A full error report will be given back to the user of all errors found.
This differs to interpreted languages as they return one error at a time.

Step 3: code generation

Once the code has successfully passed the first two stages, it’s time to generate the code.
During this stage object or machine code is generated.
This is what the CPU actually works with to make your program run.

Step 4: optimisation

After your code has been generated into machine or object code it will be optimised for efficiency.
The purpose is to make the binary footprint as small as possible and will remove procedures and variables that are written into the code but never used.

1Components of a Computer

1.1Structure & Function of the Processor

1.1.1Structure of the CPU

1.1.2Fetch, Decode, Execute Cycle

1.1.3Factors Affecting CPU Performance

1.1.4CPU Architecture

1.2Types of Processors

1.2.1CISC & RISC

1.2.2Multicore & Parallel Cores

1.3Input, Output & Storage

1.3.1Computer Systems

1.3.2Magnetic Storage

1.3.3Optical Storage

1.3.4Types of Optical Storage

1.3.5Types of Memory

1.3.6Flash Memory

1.3.7Virtual Memory

2Software & Software Development

3Exchanging Data

4Data Types, Data Structures & Algorithms

4.1Data Types

4.1.1Data Types

4.1.2Arrays & Strings

4.1.3Representing Numbers

4.1.4Binary Arithmetic

4.1.5Hexadecimal

4.1.6Converting Binary Numbers

4.1.7Floating Points in Binary

4.1.8Floating Point Arithmetic

4.1.9Bitwise Manipulation

4.1.10Character Sets

4.2Data Structures

4.2.1Arrays, Linked Lists & Queues

4.2.2Graphs, Hash Tables & Stacks

4.2.3Trees

4.3Boolean Algebra

4.3.1Computational Logic

4.3.2Boolean Logic

4.3.3Karnaugh Maps

4.3.4Boolean Identities

4.3.5Flip Flops & Adder Circuits

5Legal, Moral, Cultural & Ethical Issues

5.1Computing Related Legislation

5.1.1Data Protection Act (1998)

5.1.2Computer Misuse Act (1990)

5.1.3Copyright Designs and Patents Act (1988)

5.1.4Regulation of Investigatory Powers Act (2000)

5.2Moral & Ethical Issues

5.2.1Online Activity Tracking

5.2.2Censorship

5.2.3Cultural Issues

5.2.4Environmental Issues

5.2.5Layout, Colour Paradigms & Character Sets

6Elements of Computational Thinking

6.1Thinking Abstractly

6.1.1Abstraction

6.2Thinking Procedurally

6.2.1Decomposition

6.3Thinking Logically

6.3.1Pseudocode & Flow Diagrams

7Problem Solving & Programming

7.1Programming Techniques

7.1.1Programming Fundamentals

7.1.2Modularity

7.2Programming Construction

7.2.1Integrated Development Environments

7.2.2Testing

8Algorithms

8.1Algorithms

8.1.1Interpreting, Correcting & Completing Algorithm

8.1.2Sort Algorithms

8.1.3Insertion & Merge Sort

8.1.4Search Algorithms

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