Method: Voodoo::ARMGasGenerator#value_ref

Defined in:
lib/voodoo/generators/arm_gas_generator.rb

#value_ref(x, register) ⇒ Object

Returns a reference to a value. For immediate values that fit in 8 bits, this returns the value itself (in ARM syntax). For all other values, loads the value into a register and returns the name of the register. If the value is already in a register, the name of that register is returned. Else, the value is loaded into the register specified as the second argument.



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# File 'lib/voodoo/generators/arm_gas_generator.rb', line 963

def value_ref x, register
  if substitution? x
	x = substitute_number x[1]
  end
	
  if integer? x
    if x >= 0 && x <= 255
      return "\##{x}"
    elsif x >= -255 && x < 0
      emit "mvn #{register}, \##{-(x + 1)}\n"
      return register
    else
      lbl = add_constant x
      emit "ldr #{register}, #{lbl}\n"
      return register
    end
  elsif symbol? x
    binding = @environment[x]
	if binding.kind_of? Symbol
	  # Value is already in a register. Return register name.
	  return binding
	elsif binding.kind_of? Integer
	  # Value is on the stack. Load from the stack.
	  emit "ldr #{register}, #{offset_reference binding}\n"
	  return register
	else
      # Assume global
      @symbol_tracker.use x
      lbl = add_constant x
      emit "ldr #{register}, #{lbl}\n"
      return register
    end
  elsif at_expr? x
    load_at x[1], register
  else
    raise "Don't know how to load #{x.inspect}"
  end
end