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How do we construct a top-down parser that can evaluate semantic rules during the parsing for an L-attributed definition? Illustrate with an example. Describe the parse tree method of evaluating semantic rules. What are its limitations? How do we evaluate semantic rules using the rule-based method? Describe a recursive evaluator with an example. How do […]

1.       What is a symbol table? Explain how the symbol table in a compiler can be implemented by a hash table. 2.       Explain some of the productions and the semantic actions pertaining to the processing of the declarations in a semantic analyser for C language. 3.       Explain static and dynamic type checking with examples 4.      

1.       What is name equivalence? In what context is name equivalence used during the type checking? Illustrate with an example in C language. 2.       Write an algorithm to check the equivalence of two type expressions in C language represented by a linked list. 3.       Explain some of the productions and the semantic actions pertaining to

A compiler can choose one of the two options (a) Translate the input source into intermediate code and then convert it to final machine code; (b) Directly generate the final machine code from the input source. What is the preferred option and why? Describe the three address code form of the intermediate code. List out

Compare the different methods of implementing three address code. How is an abstract syntax tree different from a parse tree? List out some of the nodes in the AST for a C compiler? Translate a C statement ‘a = b + c – (4ab + 3*c);’ into TAC. How are the binary operators like +,

1.       How is the offset calculated for a multidimensional array reference? Derive the formula. 2.       Translate the C statements ‘p=& arr[3]; *p=10;’ into TAC. What TAC operators are useful during the translation of pointer accesses? 3.       Translate the C statement ‘x.age = 30;’ into TAC. Assume that the field ‘age’ is at an offset of

1.       In semantic analysis, the global variables declared in the input source are converted to symbol table entries. How are the symbol table entries translated into corresponding declarations in x86 assembly language by the target code generator? Illustrate by example for   (a) simple variables   (b) arrays. 2.       How do you generate target code for arithmetic

Illustrate by example, the calling and return sequences in C runtime environment. Explain the terms (a) Actual parameters. (b) Formal parameters. Illustrate with an example. Explain (a) call-by-reference and (b) call-by-value parameter-passing mechanisms. Illustrate with an example. Explain (a) call-by-value-result and (b) call-by-name parameter-passing mechanisms. Illustrate with an example. How do the run-time environments of

The target code generator takes the intermediate code as the input and generates a target program as output. The target program can take one of the three forms (1) assembly language program; (2) relocatable code; (3) absolute code. The memory organisation of FORTRAN77 runtime environment does not have a stack or a heap for dynamic

1.       How are local variables resolved to memory addresses during the translation of intermediate code to target code by the code generator? Draw the stack layout showing the local variables. 2.       How are numeric and string literals in the intermediate code translated to the target code? Illustrate with an example each.