fix while statement

logic was broken, or inversed
had to lay the code out a bit funny, but it works and makes sense

lib/soml/compiler/while_statement.rb

@@ -6,24 +6,23 @@ module Soml
       branch_type , condition , statements = *statement
       condition = condition.first
 
-      add_code  start = Register::Label.new(statement , "while_start" )
+      condition_label = Register::Label.new(statement , "condition_label")
+      # unconditionally branch to the condition upon entering the loop
+      add_code Register::Branch.new(statement,condition_label)
 
+      add_code  start = Register::Label.new(statement , "while_start" )
+      reset_regs
+      process_all(statements)
+
+      # This is where the loop starts, though in subsequent iterations it's in the middle
+      add_code condition_label
       reset_regs
       process(condition)
 
       branch_class = Object.const_get "Register::Is#{branch_type.capitalize}"
       # this is where the while ends and both branches meet
-      merge = Register::Label.new(statement , "while_merge")
-      add_code branch_class.new( condition , merge )
+      add_code branch_class.new( condition , start )
 
-      reset_regs
-      process_all(statements)
-
-      # unconditionally branch to the start
-      add_code Register::Branch.new(statement,start)
-
-      # continue execution / compiling at the merge block
-      add_code merge
       nil # statements don't return anything
     end
   end