Externalise register allocation into own class

On the way to the register allocation

lib/risc/allocator.rb

@@ -0,0 +1,62 @@
+module Risc
+  # just moved compilers register related stuff here
+  #
+  # Allocator keeps a list of registers and passes them out
+  # upon request. they must be returned in order
+  class Allocator
+
+    def initialize()
+      @regs = []
+      reset_regs
+    end
+    attr_reader :regs
+
+    def regs_empty?
+      @regs.empty?
+    end
+    def add_reg(reg)
+      raise "not reg #{reg.class}" unless reg.is_a?(RegisterValue)
+      @regs << reg
+    end
+    def pop
+      @regs.pop
+    end
+    def clear_regs
+      @regs.clear
+    end
+
+    # require a (temporary) register. code must give this back with release_reg
+    # Second extra parameter may give extra info about the value, see RegisterValue
+    def use_reg( type , extra = {} )
+      raise "Not type #{type.inspect}:#{type.class}" unless type.is_a?(Symbol) or type.is_a?(Parfait::Type)
+      if @regs.empty?
+        reg = Risc.tmp_reg(type , extra)
+      else
+        reg = @regs.last.next_reg_use(type , extra)
+      end
+      @regs << reg
+      return reg
+    end
+
+    def copy( reg , source )
+      copied = use_reg reg.type
+      add_code Register.transfer( source , reg , copied )
+      copied
+    end
+
+    # releasing a register (accuired by use_reg) makes it available for use again
+    # thus avoiding possibly using too many registers
+    def release_reg( reg )
+      last = @regs.pop
+      raise "released register in wrong order, expect #{last} but was #{reg}" if reg != last
+    end
+
+    # reset the registers to be used. Start at r4 for next usage.
+    # Every statement starts with this, meaning each statement may use all registers, but none
+    # get saved. Statements have affect on objects.
+    def reset_regs
+      @regs.clear
+    end
+
+  end
+end

lib/risc/callable_compiler.rb

@@ -18,10 +18,10 @@ module Risc
     def initialize( callable  , slot_label)
       raise "No method" unless callable
       @callable = callable
-      @regs = []
+      @allocator = Allocator.new
       @constants = []
       @current = @risc_instructions = slot_label.risc_label(self)
-      reset_regs
+      @allocator.reset_regs
     end
     attr_reader :risc_instructions , :constants , :callable , :current
 
@@ -54,14 +54,7 @@ module Risc
     # require a (temporary) register. code must give this back with release_reg
     # Second extra parameter may give extra info about the value, see RegisterValue
     def use_reg( type , extra = {} )
-      raise "Not type #{type.inspect}" unless type.is_a?(Symbol) or type.is_a?(Parfait::Type)
+      @allocator.use_reg(type, extra)
-      if @regs.empty?
-        reg = Risc.tmp_reg(type , extra)
-      else
-        reg = @regs.last.next_reg_use(type , extra)
-      end
-      @regs << reg
-      return reg
     end
 
     # resolve the type of the slot, by inferring from it's name, using the type
@@ -106,7 +99,7 @@ module Risc
     # releasing a register (accuired by use_reg) makes it available for use again
     # thus avoiding possibly using too many registers
     def release_reg( reg )
-      last = @regs.pop
+      last = @allocator.pop
       raise "released register in wrong order, expect #{last} but was #{reg}" if reg != last
     end
 
@@ -114,7 +107,7 @@ module Risc
     # Every statement starts with this, meaning each statement may use all registers, but none
     # get saved. Statements have affect on objects.
     def reset_regs
-      @regs.clear
+      @allocator.clear_regs
     end
 
     # Build with builder (see there), adding the created instructions
@@ -150,3 +143,4 @@ module Risc
 
   end
 end
+require_relative "allocator"

lib/slot_machine/slotted_object.rb

@@ -18,6 +18,7 @@ module SlotMachine
     # the register returned
     def to_register(compiler, source)
       type = known_object.get_type
+      raise "not sym for #{known_object}" if type.is_a?(String)
       right = compiler.use_reg( type )
       const = Risc.load_constant(source, known_object , right)
       compiler.add_code const

test/risc/test_allocator.rb

@@ -0,0 +1,34 @@
+require_relative "../helper"
+
+module Risc
+  class TestAllocator < MiniTest::Test
+
+    def setup
+      Parfait.boot!(Parfait.default_test_options)
+      @allocator = Allocator.new
+    end
+    def tmp_reg
+      Risc.tmp_reg(:Type)
+    end
+    def test_regs
+      assert_equal Array , @allocator.regs.class
+    end
+    def test_empty
+      assert @allocator.regs_empty?
+    end
+    def test_add_ok
+      assert_equal Array, @allocator.add_reg(tmp_reg).class
+    end
+    def test_add_fail
+      assert_raises{ @allocator.add_reg(1)}
+    end
+    def test_pop
+      @allocator.add_reg(tmp_reg)
+      assert_equal RegisterValue , @allocator.pop.class
+    end
+    def test_clear
+      @allocator.clear_regs
+      assert @allocator.regs_empty?
+    end
+  end
+end

test/risc/test_callable_compiler.rb

@@ -9,7 +9,32 @@ module Risc
     end
   end
   class TestCallableCompiler < MiniTest::Test
-
+    def setup
+      Parfait.boot!({})
+      label = SlotMachine::Label.new("hi","ho")
+      @compiler = CallableCompiler.new(FakeCallable.new  , label)
+    end
+    def test_ok
+      assert @compiler
+    end
+    def test_current
+      assert @compiler.current
+    end
+    def test_current_label
+      assert_equal Label , @compiler.current.class
+      assert_equal "ho" , @compiler.current.name
+    end
+    def test_slot
+      assert @compiler.risc_instructions
+    end
+    def test_const
+      assert_equal Array , @compiler.constants.class
+    end
+    def test_use_reg
+      @compiler.use_reg(:Type)
+    end
+  end
+  class TestFakeCallableCompiler < MiniTest::Test
     def setup
       Parfait.boot!({})
       label = SlotMachine::Label.new("hi","ho")