Compiler Design (AL-703 (A)) - Important Questions

Construct a Directed Acyclic Graph (DAG) for the following expression and show how common subexpressions are eliminated. Derive the optimized three-address code.

$a + a\times\left( b - c \right) + \left( b - c \right) \times d$

Define Directed Acyclic Graph (DAG). Construct a DAG for the following expression and indicate any opportunities for common-subexpression elimination and code reduction:

$p + p\times\left( q - r \right) + \left( q - r \right) \times s$

Explain in detail loop optimization techniques. Illustrate with a clear example how loop-invariant code motion and induction variable elimination reduce execution cost.

Discuss in brief about Constant Folding. Give a small example showing how constant folding transforms intermediate code.

Explain in detail about storage allocation strategies used by compilers (static, stack-dynamic, heap-dynamic). Discuss advantages and disadvantages of each strategy.

Explain Activation Records (stack frames) and run-time storage organization. Describe different parameter passing methods and show the sequence of actions during a procedure call and return.

Explain peephole optimization and dead-code elimination with examples. Show how a small sequence of three-address code can be simplified by peephole rules.

Write a short note on procedure calls. Discuss calling conventions, parameter passing, return values and compiler support for nested/procedural scopes.