44 lines
1.5 KiB
Ruby
44 lines
1.5 KiB
Ruby
module Mom
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# Transering the arguments from the current frame into the next frame
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#
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# This could be _done_ at this level, and in fact used to be.
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# The instruction was introduced to
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# 1. make optimisations easier
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# 2. localise the inevitable change
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#
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# 1. The optimal risc implementation for this loads old and new frames into registers
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# and does a whole bunch of transfers
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# But if we do individual SlotMoves here, each one has to load the frames,
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# thus making advanced analysis/optimisation neccessary to achieve the same effect.
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#
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# 2. Closures will have to have access to variables after the frame goes out of scope
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# and in fact be able to change the parents variables. The current design does not allow
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# for this, and so will have to be change in the not so distant future.
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#
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class ArgumentTransfer < Instruction
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attr_reader :receiver , :arguments
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# receiver is a slot_definition
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# arguments is an array of SlotLoads
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def initialize( receiver,arguments )
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@receiver , @arguments = receiver , arguments
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raise "Receiver not SlotDefinition #{@receiver}" unless @receiver.is_a?(SlotDefinition)
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@arguments.each{|a| raise "args not SlotLoad #{a}" unless a.is_a?(SlotLoad)}
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end
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def to_risc(compiler)
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transfer = SlotLoad.new([:message , :next_message , :receiver] , @receiver).to_risc(compiler)
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compiler.reset_regs
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@arguments.each do |arg|
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transfer << arg.to_risc(compiler)
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compiler.reset_regs
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end
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transfer
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end
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end
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end
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