GATE CSE 1998 | Question: 1.27

Question

Type checking is normally done during

• A. lexical analysis
• B. syntax analysis
• C. syntax directed translation
• D. code optimization

Answer 1

The answer is c .

The use of syntax analyser is used to create parse Tree. But along with Grammar as input to Syntax Analyser we add even semantic rules which form the basis of Syntax Directed Translation That help us in Evaluation of Expression .Remember that

Syntax Directed Translation is used in following cases

1. Conversion of infix to Postfix
2. Calculation of infix expression
3. For creating a Acyclic graph
4. Type Checking
5. Conversion of Binary number to Decimal
6. Counting the numbers of bits (0 or 1 ) in a binary number
7. Creation of syntax tree
8. To generate Intermediate code
9. Storing the data into Symbol table

Comments

is syntax directed translation is done semantic analyser phase?

third phase of compiler.

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Yes. @Nirmalbbll . But not only semantic phase. It used during Intermediate code generation also.

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Type checking is done during the semantic analysis phase, and Syntax-Directed Translation (SDT) is the tool or method used to implement and perform those semantic checks.

Relationship Between Semantic Analysis and SDT

Semantic Analysis: This is a major semantic analysis phase of a compiler. Its job is to check the meaning of a program ensuring things like type consistency, variable declarations, and scope rules are correct.

Syntax-Directed Translation (SDT): This is the underlying mechanism or formal technique (using semantic rules attached to grammar productions) that the compiler uses to carry out these checks during parsing or tree traversal.