158 lines
6.2 KiB
Ruby
158 lines
6.2 KiB
Ruby
module Soml
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# Compiling is the conversion of the AST into 2 things:
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# - code (ie sequences of Instructions inside Methods)
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# - an object graph containing all the Methods, their classes and Constants
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#
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# Some compile methods just add code, some may add Instructions while
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# others instantiate Class and Method objects
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#
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# Everything in ruby is an statement, ie returns a value. So the effect of every compile
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# is that a value is put into the ReturnSlot of the current Message.
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# The compile method (so every compile method) returns the value that it deposits.
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#
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# The process uses a visitor pattern (from AST::Processor) to dispatch according to the
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# type the statement. So a s(:if xx) will become an on_if(node) call.
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# This makes the dispatch extensible, ie Expressions may be added by external code,
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# as long as matching compile methods are supplied too.
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#
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# A compiler can also be used to generate code for a method without AST nodes. In the same way
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# compile methods do, ie adding Instructions etc. In this way code may be generated that
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# has no code equivalent.
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#
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# The Compiler also keeps a list of used registers, from which one may take to use and return to
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# when done. The list may be reset.
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#
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# The Compiler also carries method and class instance variables. The method is where code is
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# added to (with add_code). To be more precise, the @current instruction is where code is added
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# to, and that may be changed with set_current
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# All Statements reset the registers and return nil.
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# Expressions use registers and return the register where their value is stored.
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# Helper function to create a new compiler and compie the statement(s)
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def self.compile statement
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compiler = Compiler.new
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compiler.process statement
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end
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class Compiler < AST::Processor
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def initialize( method = nil )
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@regs = []
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return unless method
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@method = method
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@clazz = method.for_class
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@current = method.instructions
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end
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attr_reader :clazz , :method
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def handler_missing node
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raise "No handler on_#{node.type}(node)"
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end
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# create the method, do some checks and set it as the current method to be added to
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# class_name and method_name are pretty clear, args are given as a ruby array
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def create_method( class_name , method_name , args)
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raise "create_method #{class_name}.#{class_name.class}" unless class_name.is_a? Symbol
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clazz = Register.machine.space.get_class_by_name class_name
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raise "No such class #{class_name}" unless clazz
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create_method_for( clazz , method_name , args)
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end
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# create a method for the given class ( Parfait class object)
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# method_name is a Symbol
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# args a ruby array
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# the created method is set as the current and the given class too
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# return the compiler (for chaining)
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def create_method_for clazz , method_name , args
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@clazz = clazz
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raise "create_method #{method_name}.#{method_name.class}" unless method_name.is_a? Symbol
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arguments = []
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args.each_with_index do | arg , index |
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unless arg.is_a? Parfait::Variable
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arg = Parfait::Variable.new arg , "arg#{index}".to_sym
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end
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arguments << arg
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end
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@method = clazz.create_instance_method( method_name , Register.new_list(arguments))
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self
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end
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# add method entry and exit code. Mainly save_return for the enter and
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# message shuffle and FunctionReturn for the return
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# return self for chaining
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def init_method
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source = "_init_method"
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@method.instructions = Register::Label.new(source, "#{method.for_class.name}.#{method.name}")
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@current = enter = method.instructions
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add_code Register::Label.new( source, "return")
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# move the current message to new_message
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add_code Register::RegisterTransfer.new(source, Register.message_reg , Register.new_message_reg )
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# and restore the message from saved value in new_message
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add_code Register.get_slot("_init_method_",:new_message , :caller , :message )
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#load the return address into pc, affecting return. (other cpus have commands for this, but not arm)
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add_code Register::FunctionReturn.new( source , Register.new_message_reg , Register.resolve_index(:message , :return_address) )
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@current = enter
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self
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end
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# set the insertion point (where code is added with add_code)
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def set_current c
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@current = c
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end
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# add an instruction after the current (insertion point)
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# the added instruction will become the new insertion point
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def add_code instruction
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unless instruction.is_a?(Register::Instruction)
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raise instruction.to_s
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end
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@current.insert(instruction) #insert after current
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@current = instruction
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self
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end
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# require a (temporary) register. code must give this back with release_reg
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def use_reg type , value = nil
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if @regs.empty?
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reg = Register.tmp_reg(type , value)
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else
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reg = @regs.last.next_reg_use(type , value)
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end
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@regs << reg
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return reg
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end
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# releasing a register (accuired by use_reg) makes it available for use again
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# thus avoiding possibly using too many registers
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def release_reg reg
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last = @regs.pop
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raise "released register in wrong order, expect #{last} but was #{reg}" if reg != last
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end
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# reset the registers to be used. Start at r4 for next usage.
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# Every statement starts with this, meaning each statement may use all registers, but none
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# get saved. Statements have affect on objects.
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def reset_regs
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@regs.clear
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end
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end
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end
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require_relative "ast_helper"
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require_relative "compiler/assignment"
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require_relative "compiler/basic_values"
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require_relative "compiler/call_site"
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require_relative "compiler/class_field"
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require_relative "compiler/class_statement"
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require_relative "compiler/collections"
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require_relative "compiler/field_def"
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require_relative "compiler/field_access"
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require_relative "compiler/function_definition"
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require_relative "compiler/if_statement"
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require_relative "compiler/name_expression"
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require_relative "compiler/operator_value"
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require_relative "compiler/return_statement"
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require_relative "compiler/statement_list"
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require_relative "compiler/while_statement"
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