make operator_instruction single ass

create result register automatically
usually not used, but register allocation will sort that

test/risc/instructions/test_operator_instruction.rb

@@ -0,0 +1,23 @@
+require_relative "../helper"
+
+module Risc
+  class TestOperatorInstruction < MiniTest::Test
+    def setup
+      Parfait.boot!({})
+      @left = RegisterValue.new(:left , :Integer)
+      @right = RegisterValue.new(:right , :Integer)
+    end
+    def risc(i)
+      @left.op :- , @right
+    end
+    def test_min
+      assert_operator 1 , :- , :left , :right , "op_-_"
+    end
+    def test_reg
+      result = risc(1).result
+      assert_equal RegisterValue , result.class
+      assert_equal "Integer_Type" , result.type.name
+      assert result.symbol.to_s.start_with?("op_-_")
+    end
+  end
+end