Understanding Symbol Table Management in Program Compilation

Symbol table management is crucial in program compilation as it involves gathering information about names and constants, constructing storage structures, and aiding different phases like lexical and syntactic analysis, semantic analysis, code generation, and error handling. The symbol table serves as a data structure where program objects' details are stored and utilized throughout the compilation process.

• Symbol Table Management
• Program Compilation
• Compiler Phases
• Semantic Analysis
• Code Generation

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1. Symbol Tables Symbol Tables Gather information about names and constants which are in a program. Symbol table management refers to the symbol table s storage structure, its construction in the analysis phase and its use during the whole compilation. 1. A symbol table is a data structure, where information about program objects is gathered. 2. Is used in all phases of compiler. 3. The symbol table is built up during the lexical and syntactic analysis. 4. Help for other phases during compilation: Semantic analysis: type conflict? Code generation: how much and what type of run-time space is to be allocated? Error handling: Has the error message "Variable A undefined"

2. Example: Example: Let the following segment of source program is input to lexical analysis: Identifier Index Name Constant Tokens Table Type Index Name Token Index

3. Tokens Table Type Keyword Token If Index Identifier Index Name Constant Index Value

4. Tokens Table Type Keyword Identifier Token If A Index 1 Identifier Index 1 Name A Constant Index Value

5. Tokens Table Type Keyword Identifier Identifier Relation operator Tokens Table Type Keyword Token If A A >= Index Index Token If 1 1 Identifier Index 1 Name A Constant Index Value

6. Tokens Table Type Keyword Identifier Relation operator Relation operator Constant Tokens Table Type Keyword Identifier Token If A >= >= 100 Index Index Token If A 1 1 1 Identifier Index 1 Name A Constant Constant Index Index Value Value 1 100

7. Tokens Table Type Keyword Identifier Relation operator Constant Keyword Token If A >= 100 Then Index 1 1 Identifier Index 1 Name A Constant Index Value 1 100

8. Tokens Table Type Keyword Identifier Relation operator Constant Keyword Keyword Token If A >= 100 Then Begin Index 1 1 Identifier Index 1 Name A Constant Index Value 1 100

9. Tokens Table Type Keyword Identifier Relation operator Constant Keyword Keyword Identifier Token If A >= 100 Then Begin X Index 1 1 Identifier 2 Index 1 2 Name A X Constant Index Value 1 100

10. Tokens Table Type Keyword Identifier Relation operator Constant Keyword Keyword Identifier Assignment operator Token If A >= 100 Then Begin X := Index 1 1 2 Identifier Index 1 2 Name A X Constant Index Value 1 100

11. Tokens Table Type Keyword Identifier Relation operator Constant Keyword Keyword Identifier Assignment operator Identifier Token If A >= 100 Then Begin X := y1 Index 1 1 2 Identifier 3 Index 1 2 3 Name A X y1 Constant Index Value 1 100

12. Tokens Table Type Keyword Identifier Relation operator Constant Keyword Keyword Identifier Assignment operator Identifier Operation operator Token If A >= 100 Then Begin X := y1 + Index 1 1 2 Identifier Index 1 2 3 Name A X y1 3 Constant Index Value 1 100

13. Tokens Table Type Keyword Identifier Relation operator Constant Keyword Keyword Identifier Assignment operator Identifier Operation operator Constant Token If A >= 100 Then Begin X := y1 + 5.6 Index 1 1 2 Identifier 3 Index 1 2 3 Name A X y1 2 Constant Index Value 1 100 2 5.6

14. Tokens Table Type Keyword Identifier Relation operator Constant Keyword Keyword Identifier Assignment operator Identifier Operation operator Constant Punctuation Token If A >= 100 Then Begin X := y1 + 5.6 ; Index 1 1 2 Identifier Index 1 2 3 Name A X y1 3 2 Constant Index Value 1 100 2 5.6

15. Tokens Table Type Keyword Identifier Relation operator Constant Keyword Keyword Identifier Assignment operator Identifier Operation operator Constant Punctuation Identifier Token If A >= 100 Then Begin X := y1 + 5.6 ; Count Index 1 1 2 Identifier Index 1 2 3 4 Name A X y1 Count 3 2 4 Constant Index Value 1 100 2 5.6

16. Tokens Table Type Keyword Identifier Relation operator Constant Keyword Keyword Identifier Assignment operator Identifier Operation operator Constant Punctuation Identifier Assignment operator Token If A >= 100 Then Begin X := y1 + 5.6 ; Count := Index 1 1 2 Identifier Index 1 2 3 4 Name A X y1 Count 3 2 4 Constant Index Value 1 100 2 5.6

17. Tokens Table Type Keyword Identifier Relation operator Constant Keyword Keyword Identifier Assignment operator Identifier Operation operator Constant Punctuation Identifier Assignment operator Identifier Token If A >= 100 Then Begin X := y1 + 5.6 ; Count := A Index 1 1 Identifier 2 Index 1 2 3 4 Name A X y1 Count 3 2 4 Constant 1 Index Value 1 100 2 5.6

18. Tokens Table Type Keyword Identifier Relation operator Constant Keyword Keyword Identifier Assignment operator Identifier Operation operator Constant Punctuation Identifier Assignment operator Identifier Operation operator Token If A >= 100 Then Begin X := y1 + 5.6 ; Count := A * Index 1 1 Identifier 2 Index 1 2 3 4 Name A X y1 Count 3 2 4 Constant 1 Index Value 1 100 2 5.6 3 4

19. Tokens Table Type Keyword Identifier Relation operator Constant Keyword Keyword Identifier Assignment operator Identifier Operation operator Constant Punctuation Identifier Assignment operator Identifier Operation operator Constant Token If A >= 100 Then Begin X := y1 + 5.6 ; Count := A * 4 Index 1 1 Identifier 2 Index 1 2 3 4 Name A X y1 Count 3 2 4 Constant 1 Index Value 1 100 3 2 5.6 3 4

20. Tokens Table Type Keyword Identifier Relation operator Constant Keyword Keyword Identifier Assignment operator Identifier Operation operator Constant Punctuation Identifier Assignment operator Identifier Operation operator Constant Punctuation Token If A >= 100 Then Begin X := y1 + 5.6 ; Count := A * 4 ; Index 1 1 2 Identifier Index 1 2 3 4 Name A X y1 Count 3 2 4 Constant 1 Index Value 1 100 3 2 5.6 3 4

21. Tokens Table Type Keyword Identifier Relation operator Constant Keyword Keyword Identifier Assignment operator Identifier Operation operator Constant Punctuation Identifier Assignment operator Identifier Operation operator Constant Punctuation Keyword Token If A >= 100 Then Begin X := y1 + 5.6 ; Count := A * 4 ; End Index 1 1 Identifier 2 Index 1 2 3 4 Name A X y1 Count 3 2 4 Constant Index Value 1 1 100 3 2 5.6 3 4

22. Tokens Table Type Keyword Identifier Relation operator Constant Keyword Keyword Identifier Assignment operator Identifier Operation operator Constant Punctuation Identifier Assignment operator Identifier Operation operator Constant Punctuation Keyword Punctuation Token If A >= 100 Then Begin X := y1 + 5.6 ; Count := A * 4 ; End ; Note: These tables in above are saving in storage structure which called Symbol Table. Index 1 1 2 Identifier Index 1 2 3 4 Name A X y1 Count 3 2 4 Constant 1 Index Value 1 100 3 2 5.6 3 4