High-level Optimizations (Cont.)

• Many powerful transformations no longer possible at logic optimization

  • Comparator sharing for relational operations
  • Function transformations
  • Resource sharing/allocation; e.g., ALU to perform numerous operations
  • Bit-pruning: providing only bits that are needed
  • Constant folding: replacing operators whose arguments are constants with constants
  • Constant propagation
  • Expression sharing
  • Expression migration: moving repeated expressions out of loops, if clauses, and case statement clauses where possible
  • Dead code removal

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From [MGC92].