new (and successful :) ) story for 'parent/overridden irtrees'. basically, if we have a rule which maps some eval X's type from A -> B, we preserve the original ir-tree compilation of A in the 'history' when we inevitably produce the ir-tree compilation of B. this can be used for accesses on overridden evaluations, and it allows us to implement $ in auto view rules.

src/mule/mule_main.cpp

@@ -1624,7 +1624,7 @@ struct Bitmap
   int width;
   int height;
 };
-// raddbg_auto_view_rule(Bitmap, bitmap(base, width, height));
+raddbg_auto_view_rule(Bitmap, lens:bitmap($.base, $.width, $.height));
 
 static unsigned int
 mule_bswap_u32(unsigned int x)