[debug] record the last cfg

src/cmp/cmpbackend-cxx/cmpc-util.lsp

@@ -21,6 +21,7 @@
     #-complex-float nil)
 
 (defvar *bir*)
+(defvar *last-bir*)                     ;debug
 
 ;;; Compiled code uses the following kinds of variables:
 ;;; 1. Vi, declared explicitely, either unboxed or not (*lcl*, next-lcl)
@@ -156,6 +157,7 @@
           (*unwind-exit* '(LEAVE))
           (*destination* *exit*)
           (*bir* (make-bir)))
+     (setf *last-bir* *bir*)
      (bir-embark *bir*)
      ,@body
      (bir-finish *bir*)))