Optimizer: Implement removal of no-op MOVs

lib/fisk/optimizer.rb

@@ -1,7 +1,14 @@
 class Fisk
   class Optimizer
     def optimize(insn)
-      insn
+      case insn.insn.name
+      when Instructions::MOV.name
+        if insn.operands[0].register? && insn.operands[1].register? && insn.operands[0].name == insn.operands[1].name
+          return nil
+        end
+      end
+
+      return insn
     end
   end
 end

test/test_performance_optimization.rb

@@ -22,5 +22,15 @@ def test_no_change
       #
       assert_equal buf.string, "\x4D\x89\xD1".b
     end
+
+    def test_remove_no_op_instruction
+      buf = StringIO.new(''.b)
+
+      fisk.mov R9, R9
+
+      fisk.write_to buf
+
+      assert_equal buf.string, "".b
+    end
   end
 end