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Implementing Parameter Passing

• ALGOL 60 and most of its descendants use the run-time stack

• Value--copy it to the stack; references are indirect to the stack

• Result--same

• Reference--regardless of form, put the address in the stack

• Name:
  • Run-time resident code segments or subprograms evaluate the address of the parameter
  • Called for each reference to the formal
  • These are called thunks
  • Very expensive, compared to reference or value-result