Dévai Gergely @ ELTE

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=== Sample exam questions (theory part) ===

  - What is the task of the lexer?
  - Which part of the compiler is usually defined by a context-free grammar?
  - What is JIT (Just in time compilation)?
  - Write 3 token sequences that are accepted by the following grammar and 5 that are not accepted!
    - S->ab | aSb
  - Is LL(1) top-down or bottom-up?
  - How do the two basic actions of an LR(1) parser change the stack?
  - In which direction do synthesized attributes propagate information in the syntax tree?
  - What is the esp register used for?
  - Write an example assembly line with the and instruction and explain what does it do!
  - Write a code generation rule for an assignment!

=== Answers ===

  - The lexer breaks up the input character sequence to a token sequence.
  - Parser.
  - Some parts of interpreted code (eg. bytecode) are compiled to machine code in runtime to speed up program execution.
  - Accepted: ab, aabb, aaabbb; Not accepted: a, b, ba.
  - Top-down.
  - Shift pushes the next token into the stack, reduction removes the right-hand side and pushes the left-hand side of the selected grammar rule.
  - Bottom-up.
  - The esp register points to the top of the stack.
  - and eax,1: All bits of eax become zero, except the last one, which is preserved.
  - For integer type: code of the expression + mov [label of the variable],eax

Dévai Gergely @ ELTE

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