remove passes and achieve the same by translating

lib/arm/translator.rb

@@ -0,0 +1,88 @@
+module Arm
+  class Translator
+
+    # don't replace labels
+    def translate_Label code
+      nil
+    end
+
+    # Arm stores the return address in a register (not on the stack)
+    # The register is called link , or lr for short .
+    # Maybe because it provides the "link" back to the caller
+    # the vm defines a register for the location, so we store it there.
+    def translate_SaveReturn code
+      ArmMachine.str( :lr ,  code.register , 4 * code.index )
+    end
+
+    def translate_GetSlot code
+      # times 4 because arm works in bytes, but vm in words
+      ArmMachine.ldr( code.register ,  code.array , 4 * code.index )
+    end
+
+    def translate_RegisterTransfer code
+      # Register machine convention is from => to
+      # But arm has the receiver/result as the first
+      ArmMachine.mov( code.to , code.from)
+    end
+
+    def translate_SetSlot code
+      # times 4 because arm works in bytes, but vm in words
+      ArmMachine.str( code.register ,  code.array , 4 * code.index )
+    end
+
+    def translate_FunctionCall code
+      ArmMachine.call( code.method )
+    end
+
+    def translate_FunctionReturn code
+      ArmMachine.ldr( :pc ,  code.register , 4 * code.index )
+    end
+
+    def translate_LoadConstant code
+      constant = code.constant
+      if constant.is_a?(Parfait::Object) or constant.is_a? Symbol
+        return ArmMachine.add( code.register , constant )
+      else
+        return ArmMachine.mov( code.register ,  code.constant )
+      end
+    end
+
+    # This implements branch logic, which is simply assembler branch
+    #
+    # The only target for a call is a Block, so we just need to get the address for the code
+    # and branch to it.
+    def translate_Branch code
+      ArmMachine.b( code.block )
+    end
+    def translate_Syscall code
+      call_codes = { :putstring => 4 , :exit => 1    }
+      int_code = call_codes[code.name]
+      raise "Not implemented syscall, #{code.name}" unless int_code
+      send( code.name , int_code )
+    end
+
+    def putstring int_code
+      codes = ArmMachine.ldr( :r1 , Register.message_reg, 4 * Register.resolve_index(:message , :receiver))
+      codes.append ArmMachine.add( :r1 ,  :r1 , 8 )
+      codes.append ArmMachine.mov( :r0 ,  1 )
+      codes.append ArmMachine.mov( :r2 ,  12 ) # String length, obvious TODO
+      syscall(int_code , codes )
+    end
+
+    def exit int_code
+      codes = Register::Label.new(nil , "exit")
+      syscall int_code , codes
+    end
+
+    private
+
+    # syscall is always triggered by swi(0)
+    # The actual code (ie the index of the kernel function) is in r7
+    def syscall int_code , codes
+      codes.append ArmMachine.mov( :r7 ,  int_code )
+      codes.append ArmMachine.swi( 0 )
+      codes
+    end
+
+  end
+end

lib/register/instruction.rb

@@ -30,6 +30,13 @@ module Register
     end
     alias :<< :set_next
 
+    # during translation we replace one by one
+    def replace_next nekst
+      old = @next
+      @next = nekst
+      @next.append old.next
+    end
+
     # get the next instruction (without arg given )
     # when given an interger, advance along the line that many time and return.
     def next( amount = 1)
@@ -43,6 +50,19 @@ module Register
       @next = instruction
     end
 
+    # return last set instruction. ie follow the linked list until it stops
+    def last
+      code = self
+      code = code.next while( code.next )
+      return code
+    end
+
+    # set next for the last (see last)
+    # so append the given code to the linked list at the end
+    def append code
+      last.set_next code
+    end
+
     def length labels = []
       ret = 1
       ret += self.next.length( labels ) if self.next

lib/register/machine.rb

@@ -1,91 +1,56 @@
 require 'parslet/convenience'
 require_relative "collector"
 module Register
-  # The Register Machine is a object based virtual machine in which ruby is implemented.
+  # The Register Machine is a object based virtual machine on which ruby will be implemented.
   #
-  # It is minimal and realistic and low level
-  # - minimal means that if one thing can be implemented by another, it is left out. This is quite
-  #    the opposite from ruby, which has several loops, many redundant if forms and the like.
-  # - realistic means it is easy to implement on a 32 bit machine (arm) and possibly 64 bit.
-  #     Memory access,some registers of same size are the underlying hardware. (not ie byte machine)
-  # - low level means it's basic instructions are realively easily implemented in a register machine.
-  #      Low level means low level in oo terms though, so basic instruction to implement oo
-  #  #
+
   # The ast is transformed to virtual-machine objects, some of which represent code, some data.
   #
   # The next step transforms to the register machine layer, which is quite close to what actually
   #  executes. The step after transforms to Arm, which creates executables.
   #
-  # More concretely, a virtual machine is a sort of oo turing machine, it has a current instruction,
-  # executes the instructions, fetches the next one and so on.
-  # Off course the instructions are not soo simple, but in oo terms quite so.
-  #
-  # The machine is virtual in the sense that it is completely modeled in software,
-  # it's complete state explicitly available (not implicitly by walking stacks or something)
-
-  # The machine has a no register, but objects that represent it's state. There are four
-  # - message : the currently executing message (See Parfait::Message)
-  # - receiver : or self.  This is actually an instance of Message, but "hoisted" out
-  # -  frame : A pssible frame for temporary data. Also part of the message and "hoisted" out
-  # - next_message: A message object that the current activation wants to send.
-  #
-  # Messages form a linked list (not a stack) and the Space is responsible for storing
-  # and handing out empty messages
-  #
-  # The "machine" is not part of the run-time (Parfait)
 
   class Machine
     include Collector
 
     def initialize
       @parser  = Parser::Salama.new
-      @passes = [   ]
       @objects = {}
       @booted = false
     end
-    attr_reader  :passes , :space , :class_mappings , :init , :objects , :booted
+    attr_reader :space , :class_mappings , :init , :objects , :booted
 
-    # run all passes before the pass given
-    # also collect the  block to run the passes on and
-    # runs housekeeping Minimizer and Collector
-    # Has to be called before run_after
-    def run_before stop_at
-      @blocks = [@init]
+
+    # idea being that later method missing could catch translate_xxx and translate to target xxx
+    # now we just instantiate ArmTranslater and pass instructions
+    def translate_arm
+      translator = Arm::Translator.new
+      methods = []
       @space.classes.values.each do |c|
         c.instance_methods.each do |f|
-          nb = f.source.blocks
-          @blocks += nb
+          methods << f.source
         end
       end
-      @passes.each do |pass_class|
-        #puts "running #{pass_class}"
-        run_blocks_for pass_class
-        return if stop_at == pass_class
+      methods.each do |method|
+        instruction = method.instructions
+        begin
+          nekst = instruction.next
+          t = translate(translator , nekst) # returning nil means no replace
+          instruction.replace_next(t) if t
+          instruction = nekst
+        end while instruction.next
       end
     end
 
-    # run all passes after the pass given
-    # run_before MUST be called first.
-    # the two are meant as a poor mans breakoint
-    def run_after start_at
-      run = false
-      @passes.each do |pass_class|
-        if run
-          #puts "running #{pass_class}"
-          run_blocks_for pass_class
-        else
-          run = true if start_at == pass_class
-        end
-      end
+    # translator should translate from register instructio set to it's own (arm eg)
+    # for each instruction we call the translator with translate_XXX
+    #  with XXX being the class name.
+    # the result is replaced in the stream
+    def translate translator , instruction
+      class_name = instruction.class.name.split("::").last
+      translator.send( "translate_#{class_name}".to_sym , instruction)
     end
 
-    # as before, run all passes that are registered
-    # (but now finer control with before/after versions)
-    def run_passes
-      return if @passes.empty?
-      run_before @passes.first
-      run_after @passes.first
-    end
 
     # Objects are data and get assembled after functions
     def add_object o
@@ -96,25 +61,6 @@ module Register
       true
     end
 
-    # Passes may be added to by anyone who wants
-    # This is intentionally quite flexible, though one sometimes has to watch the order of them
-    # most ordering is achieved by ordering the requires and using add_pass
-    # but more precise control is possible with the _after and _before versions
-
-    def add_pass pass
-      @passes << pass
-    end
-    def add_pass_after( pass , after)
-      index = @passes.index(after)
-      raise "No such pass (#{pass}) to add after: #{after}" unless index
-      @passes.insert(index+1 , pass)
-    end
-    def add_pass_before( pass , after)
-      index = @passes.index(after)
-      raise "No such pass to add after: #{after}" unless index
-      @passes.insert(index , pass)
-    end
-
     def boot
       boot_parfait!
       @init =  Branch.new( "__init__" , self.space.get_init.source.instructions )

lib/salama.rb

@@ -13,3 +13,4 @@ require "salama-object-file"
 require "register"
 require "register/builtin/object"
 require "arm/arm_machine"
+require "arm/translator"

test/elf/test_hello.rb

@@ -4,19 +4,14 @@ class HelloTest < MiniTest::Test
 
   def check
     machine = Register.machine.boot
-    #TODO remove this hack: write proper aliases
-    statements = machine.parse_and_compile @string_input
-    output_at = "Register::CallImplementation"
-    #{}"Register::CallImplementation"
+    machine.parse_and_compile @string_input
     machine.collect
-    machine.run_before output_at
-    #puts Sof.write(machine.space)
-    machine.run_after output_at
+    machine.translate_arm
     writer = Elf::ObjectWriter.new(machine)
     writer.save "hello.o"
   end
 
-  def pest_string_put
+  def test_string_put
     @string_input    = <<HERE
 class Object
   int main()