%apply-in-frame has bitrotted

[SuperDisk]

I'm sure you're aware of this already, but I was just curious what it would take to make this work again:

ccl/lib/x86-backtrace.lisp

Line 399 in 0c0dcfa

(error "%apply-in-frame has bitrotted"))))

Right now this message appears when using r to restart a frame in the SLIME debugger.

[xrme]

I think what happened here is a side effect of a new, partly working, register allocator being added to the x86-64 backend. This allocator is opt-in-only; it's not used by default. The file Clozure/ccl/doc/compiler-changes-in-CCL-trunk.pdf contains some notes about the allocator.

Prior to that change, it was possible to know where all the frame locals, etc., were.

ccl/lib/x86-backtrace.lisp

Lines 426 to 462 in 55ebe5d

	(defun %apply-in-frame (frame function arglist)
	(target-arch-case
	(:x8632 (error "%apply-in-frame doesn't work for x8632 yet"))
	(:x8664
	(let* ((target-catch (last-catch-since frame nil))
	(start-fp (if target-catch
	(uvref target-catch x8664::catch-frame.rbp-cell)
	(%get-frame-ptr)))
	(target-xcf (last-xcf-since frame start-fp nil))
	(target-db-link (last-binding-before frame))
	(target-tsp (last-tsp-before frame))
	(target-foreign-sp (last-foreign-sp-before frame)))
	(multiple-value-bind (save0-loc save1-loc save2-loc save3-loc)
	(find-x8664-saved-nvrs frame start-fp nil)
	(let* ((thunk (%clone-x86-function #'%%apply-in-frame-proto
	frame
	target-catch
	target-db-link
	target-xcf
	target-tsp
	target-foreign-sp
	(if save0-loc
	(- save0-loc frame)
	0)
	(if save1-loc
	(- save1-loc frame)
	0)
	(if save2-loc
	(- save2-loc frame)
	0)
	(if save3-loc
	(- save3-loc frame)
	0)
	(coerce-to-function function)
	arglist
	0)))
	(funcall thunk)))))))

I think in order for this to work again, the "new" allocator would have to record debugging information about where to find the frame locals, etc.

I'm not sure, frankly, whether to try to press ahead with this "new" allocator, or to back it out.