Computer Science
Give the names of the 4 Stages of compilation
- Lexical Analysis
- Syntax Analysis
- Code Generation
- Optimisation
Describe what happens during lexical analysis
The lexer converts lexemes(words) in the source code into tokens. It scans letter by letter & any irrelevant elements e.g. white spaces, comments are removed
Describe what happens during syntax analysis
Tokens are then analysed according to the grammar of the programming language to build a syntax tree (parse tree). Syntax errors are detected in this stage
Describe what happens during code generation
Traverses through the syntax tree to generate object code that can be executed by the computer
Describe what hapens during code optimisation
It aims to reduce the execution time of the program
Give a few ways that code optimisation can reduce execution time
- Spotting and removing redundant code
- Removing subroutines that have never been called
- Removing variables and constants that have never been referenced
What assumptions can be made about the lexer
- Only creates one table
- Doesn't store duplicate entries
- Uses indexing instead of hashing