1.2.2.6 Stages of Compilation

Question 1

What are the 4 stages of compilation?

Answer 1

1) Lexical analysis

2) Syntax analysis

3) Code generation

4) Code optimisation

Question 2

What happens in the lexical analysis stage?

Answer 2

• The Lexer starts by converting lexemes from the source code into a series of tokens
• Scanned spaces, symbols are taken as indicators that word is complete
• It then checks if the lexeme is valid using a predefined set of rules that allow every lexeme to be identified as a valid token

Question 3

What can be considered a token?

Answer 3

Keywords, constants, identifiers, strings, numbers, operators and punctuation symbols

Question 4

What happens in the syntax analysis stage?

Answer 4

• Receives its inputs in the form of tokens from lexical analysers.
• Analyses the syntactical structure of the input, checking if it is in the correct syntax of the programming language it has been written in.
• It does this by analysing the token stream against production rules to detect any errors in the code

Question 5

What does the syntax analysis accomplish?

Answer 5

• Checking for errors and reporting them.
• Building an abstract syntax tree (parse tree)

Question 6

What does code optimisation do?

Answer 6

• Spotting redundant instructions and producing object code that achieves the same effect as the source program but not necessarily by the same means.
• Removing subroutines that are never called.
• Removing variables and constants that are never referenced.