anchor.diff:    (lap:mov64 :rbp :rsp)
     (:gc :frame)
     PHONY-RETURN-ADDRESS
  +  ;; Work with footholds inhibitied.
  +  (lap:gs)
  +  (lap:add64 (:object nil #.mezzano.supervisor::+thread-inhibit-footholds+)
  +             #.(ash 1 sys.int::+n-fixnum-bits+))
     ;; Find the top of the new stack.
     (lap:mov64 :rsp (:object :r11 1)) ; stack.base
     (lap:sar64 :rsp #.sys.int::+n-fixnum-bits+)
  
positive.code:   (lap:mov64 (:object :rbx #.sys.int::+delimited-continuation-prompt+) 0)
    (lap:mov64 (:object :rbx #.sys.int::+delimited-continuation-stack-pointer+) 0)
    (lap:mov64 (:object :rbx #.sys.int::+delimited-continuation-stack+) 0)
    ;; Now return to the function that originally aborted.
    (lap:leave)
    (:gc :no-frame :layout #*0 :multiple-values 0)
    (lap:ret)
    TOO-MANY-VALUES
    (:gc :frame)
    (lap:mov64 :r13 (:function error))
    (lap:mov64 :r8 (:constant "Resuming continuation ~S with too many values (MULTPLE-VALUES-LIMIT exceeded)"))
    (lap:mov32 :ecx #.(ash 1 sys.int::+n-fixnum-bits+))
  
negative.code:   (lap:mov64 :r9 (:stack 0)) ; r9 = prompt
    (lap:mov64 :r10 (:stack 1)) ; r10 = values
    ;; r8 = new continuation, r9 = prompt, r10 = values.
    ;; Work with footholds inhibitied.
    (lap:gs)
    (lap:add64 (:object nil #.mezzano.supervisor::+thread-inhibit-footholds+)
               #.(ash 1 sys.int::+n-fixnum-bits+))
    ;; Store the entry point...
    (lap:mov64 :r11 (:function %resume-delimited-continuation))
    (lap:mov64 :rax (:object :r11 #.sys.int::+fref-entry-point+))
  