Dead Code Elimination

Your Task

Implement dead code elimination on the AST.

Requirements

1. Detect and remove unreachable code:

   • Code after return statements
   • Code after break/continue
   • Branches with constant false conditions

2. Detect and remove dead stores:

   • Variable assigned but never read
   • Variable assigned twice with no read between

3. Remove empty statements:

   • Empty blocks {}
   • Expression statements with no side effects

4. Handle control flow:

   • if (false) A else B → B
   • if (true) A else B → A
   • while (false) {...} → remove entirely

5. Preserve code with side effects:

   • Function calls (might have side effects)
   • Assignments to global/volatile variables
   • I/O operations

Success Criteria

• Remove code after return
• Simplify always-true/false conditions
• Report removed code (warnings)