83 lines
3.1 KiB
Ruby
83 lines
3.1 KiB
Ruby
module Risc
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# Passes, or BlockPasses, could have been procs that just get each block passed.
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# Instead they are proper objects in case they want to save state.
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# The idea is
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# - reduce noise in the main code by having this code seperately (aspect/concern style)
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# - abstract the iteration
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# - allow not yet written code to hook in
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class RemoveStubs
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def run block
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block.codes.dup.each_with_index do |kode , index|
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next unless kode.is_a? StackInstruction
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if kode.registers.empty?
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block.codes.delete(kode)
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puts "deleted stack instruction in #{b.name}"
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end
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end
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end
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end
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# Operators eg a + b , must assign their result somewhere and as such create temporary variables.
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# but if code is c = a + b , the generated instructions would be more like tmp = a + b ; c = tmp
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# SO if there is an move instruction just after a logic instruction where the result of the logic
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# instruction is moved straight away, we can undo that mess and remove one instruction.
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class LogicMoveReduction
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def run block
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org = block.codes.dup
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org.each_with_index do |kode , index|
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n = org[index+1]
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next if n.nil?
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next unless kode.is_a? LogicInstruction
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next unless n.is_a? MoveInstruction
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# specific arm instructions, don't optimize as don't know what the extra mean
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# small todo. This does not catch condition_code that are not :al
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next if (n.attributes.length > 3) or (kode.attributes.length > 3)
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if kode.result == n.from
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puts "Logic reduction #{kode} removes #{n}"
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kode.result = n.to
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block.codes.delete(n)
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end
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end
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end
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end
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# Sometimes there are double moves ie mov a, b and mov b , c . We reduce that to move a , c
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# (but don't check if that improves register allocation. Yet ?)
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class MoveMoveReduction
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def run block
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org = block.codes.dup
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org.each_with_index do |kode , index|
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n = org[index+1]
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next if n.nil?
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next unless kode.is_a? MoveInstruction
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next unless n.is_a? MoveInstruction
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# specific arm instructions, don't optimize as don't know what the extra mean
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# small todo. This does not catch condition_code that are not :al
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next if (n.attributes.length > 3) or (kode.attributes.length > 3)
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if kode.to == n.from
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puts "Move reduction #{kode}: removes #{n} "
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kode.to = n.to
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block.codes.delete(n)
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end
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end
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end
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end
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#As the name says, remove no-ops. Currently mov x , x supported
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class NoopReduction
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def run block
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block.codes.dup.each_with_index do |kode , index|
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next unless kode.is_a? MoveInstruction
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# specific arm instructions, don't optimize as don't know what the extra mean
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# small todo. This does not catch condition_code that are not :al
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next if (kode.attributes.length > 3)
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if kode.to == kode.from
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block.codes.delete(kode)
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puts "deleted noop move in #{block.name} #{kode}"
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end
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end
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end
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end
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end
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