Convert SimpleCall to new regs

Also fix bug in RegsiterValue/Slot with chain, where logic was dodgy and compiler not set

lib/risc/register_value.rb

@@ -143,8 +143,8 @@ module Risc
       when RegisterValue
         ins = Risc.transfer("#{right.type} to #{self.type}" , right , self)
       when RegisterSlot
-        raise "logic error, after creating the reg, need to transfer"
-        ins = Risc::SlotToReg.new("#{right.register.type}[#{right.index}] -> #{self.type}" , right.register , right.index , self)
+        index = right.register.resolve_index(right.index)
+        ins = SlotToReg.new("#{right.register.type}[#{right.index}] -> #{self.type}" , right.register , index , self)
       else
         raise "not implemented for #{right.class}:#{right}"
       end