In Syntax-Directed Translation (SDT), what is the difference between a Parse Tree and an Abstract Syntax Tree (AST)?
An Abstract Syntax Tree (AST) is a condensed representation of the parse tree that strips out purely grammatical non-terminals and punctuation.
Which type of Intermediate Representation (IR) uses 3 memory address fields per instruction: op, arg1, arg2, result?
Quadruples explicitly store target variable results in a 4-field structure: (op, arg1, arg2, result).
How do Triples differ from Quadruples in Three-Address Code representations?
Triples use 3 fields: (op, arg1, arg2). The location/statement number implicitly serves as the temporary variable result name.
What advantage do Indirect Triples offer over standard Triples during code optimization passes?
Indirect Triples maintain an array of pointers to triple records. Re-locating or re-ordering code during optimization requires only updating pointer indices.
Convert the arithmetic expression (a + b) * (c - d) into Postfix (Reverse Polish) Notation:
(a + b) becomes a b +; (c - d) becomes c d -; product becomes a b + c d - *.