[Sbcl-commits] CVS: sbcl/src/compiler debug.lisp,1.34,1.35 dfo.lisp,1.18,1.19 fndb.lisp,1.89,1.90 ir2tran.lisp,1.49,1.50 node.lisp,1.51,1.52 physenvanal.lisp,1.13,1.14 stack.lisp,1.12,1.13

[Alexey D. <ade...@us...>]

Update of /cvsroot/sbcl/sbcl/src/compiler
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv14118/src/compiler

Modified Files:
	debug.lisp dfo.lisp fndb.lisp ir2tran.lisp node.lisp 
	physenvanal.lisp stack.lisp 
Log Message:
0.8.10.3:
        * Merge with stack-analysis-branch.


Index: debug.lisp
===================================================================
RCS file: /cvsroot/sbcl/sbcl/src/compiler/debug.lisp,v
retrieving revision 1.34
retrieving revision 1.35
diff -u -d -r1.34 -r1.35
--- debug.lisp	4 Apr 2004 14:07:25 -0000	1.34
+++ debug.lisp	1 May 2004 11:22:39 -0000	1.35
@@ -952,6 +952,10 @@
       (format t " <deleted>"))
 
     (pprint-newline :mandatory)
+    (awhen (block-info block)
+      (format t "start stack:~{ v~D~}"
+              (mapcar #'cont-num (ir2-block-start-stack it)))
+      (pprint-newline :mandatory))
     (do ((ctran (block-start block) (node-next (ctran-next ctran))))
         ((not ctran))
       (let ((node (ctran-next ctran)))
@@ -1010,6 +1014,10 @@
                      (cast-asserted-type node)))))
         (pprint-newline :mandatory)))
 
+    (awhen (block-info block)
+      (format t "end stack:~{ v~D~}"
+              (mapcar #'cont-num (ir2-block-end-stack it)))
+      (pprint-newline :mandatory))
     (let ((succ (block-succ block)))
       (format t "successors~{ c~D~}~%"
               (mapcar (lambda (x) (cont-num (block-start x))) succ))))

Index: dfo.lisp
===================================================================
RCS file: /cvsroot/sbcl/sbcl/src/compiler/dfo.lisp,v
retrieving revision 1.18
retrieving revision 1.19
diff -u -d -r1.18 -r1.19
--- dfo.lisp	16 Nov 2003 10:19:13 -0000	1.18
+++ dfo.lisp	1 May 2004 11:22:39 -0000	1.19
@@ -91,6 +91,18 @@
     (setf (block-flag block) t)
     (dolist (succ (block-succ block))
       (find-dfo-aux succ head component))
+    (when (component-nlx-info-generated-p component)
+      ;; FIXME: We also need (and do) this walk before physenv
+      ;; analysis, but at that time we are probably not very
+      ;; interested in the actual DF order.
+      ;;
+      ;; TODO: It is probable that one of successors have the same (or
+      ;; similar) set of NLXes; try to shorten the walk (but think
+      ;; about a loop, the only exit from which is non-local).
+      (map-block-nlxes (lambda (nlx-info)
+                         (let ((nle (nlx-info-target nlx-info)))
+                         (find-dfo-aux nle head component)))
+                       block))
     (remove-from-dfo block)
     (add-to-dfo block head))
   (values))

Index: fndb.lisp
===================================================================
RCS file: /cvsroot/sbcl/sbcl/src/compiler/fndb.lisp,v
retrieving revision 1.89
retrieving revision 1.90
diff -u -d -r1.89 -r1.90
--- fndb.lisp	30 Mar 2004 16:58:26 -0000	1.89
+++ fndb.lisp	1 May 2004 11:22:39 -0000	1.90
@@ -1380,6 +1380,7 @@
 (defknown %nlx-entry (t) *)
 (defknown %%primitive (t t &rest t) *)
 (defknown %pop-values (t) t)
+(defknown %nip-values (t t &rest t) (values))
 (defknown %type-check-error (t t) nil)
 
 ;; FIXME: This function does not return, but due to the implementation

Index: ir2tran.lisp
===================================================================
RCS file: /cvsroot/sbcl/sbcl/src/compiler/ir2tran.lisp,v
retrieving revision 1.49
retrieving revision 1.50
diff -u -d -r1.49 -r1.50
--- ir2tran.lisp	13 Apr 2004 10:30:39 -0000	1.49
+++ ir2tran.lisp	1 May 2004 11:22:39 -0000	1.50
@@ -1210,16 +1210,16 @@
 (defoptimizer (sb!kernel:%caller-frame-and-pc ir2-convert) (() node block)
   (let ((ir2-physenv (physenv-info (node-physenv node))))
     (move-lvar-result node block
-			      (list (ir2-physenv-old-fp ir2-physenv)
-				    (ir2-physenv-return-pc ir2-physenv))
-			      (node-lvar node))))
+                      (list (ir2-physenv-old-fp ir2-physenv)
+                            (ir2-physenv-return-pc ir2-physenv))
+                      (node-lvar node))))
 
 ;;;; multiple values
 
 ;;; This is almost identical to IR2-CONVERT-LET. Since LTN annotates
-;;; the lvarinuation for the correct number of values (with the lvar
-;;; user responsible for defaulting), we can just pick them up from
-;;; the lvar.
+;;; the lvar for the correct number of values (with the lvar user
+;;; responsible for defaulting), we can just pick them up from the
+;;; lvar.
 (defun ir2-convert-mv-bind (node block)
   (declare (type mv-combination node) (type ir2-block block))
   (let* ((lvar (first (basic-combination-args node)))
@@ -1282,6 +1282,28 @@
     (vop reset-stack-pointer node block
 	 (first (ir2-lvar-locs 2lvar)))))
 
+(defoptimizer (%nip-values ir2-convert) ((last-nipped last-preserved &rest moved)
+                                         node block)
+  #!-x86
+  (bug "%NIP-VALUES is not implemented on this platform.")
+  #!+x86
+  (let ((2after (lvar-info (lvar-value last-nipped)))
+                                        ; pointer immediately after the nipped block
+        (2first (lvar-info (lvar-value last-preserved)))
+                                        ; pointer to the first nipped word
+        (moved-tns (loop for lvar-ref in moved
+                         for lvar = (lvar-value lvar-ref)
+                         for 2lvar = (lvar-info lvar)
+                         ;when 2lvar
+                         collect (first (ir2-lvar-locs 2lvar)))))
+    (aver (eq (ir2-lvar-kind 2after) :unknown))
+    (aver (eq (ir2-lvar-kind 2first) :unknown))
+    (vop* %%nip-values node block
+	 ((first (ir2-lvar-locs 2after))
+          (first (ir2-lvar-locs 2first))
+          (reference-tn-list moved-tns nil))
+         ((reference-tn-list moved-tns t)))))
+
 ;;; Deliver the values TNs to LVAR using MOVE-LVAR-RESULT.
 (defoptimizer (values ir2-convert) ((&rest values) node block)
   (let ((tns (mapcar (lambda (x)

Index: node.lisp
===================================================================
RCS file: /cvsroot/sbcl/sbcl/src/compiler/node.lisp,v
retrieving revision 1.51
retrieving revision 1.52
diff -u -d -r1.51 -r1.52
--- node.lisp	4 Apr 2004 14:07:25 -0000	1.51
+++ node.lisp	1 May 2004 11:22:39 -0000	1.52
@@ -373,7 +373,8 @@
   ;; inline expansion. Unlike NEW-FUNCTIONALS, this is not disjoint
   ;; from COMPONENT-LAMBDAS.
   (reanalyze-functionals nil :type list)
-  (delete-blocks nil :type list))
+  (delete-blocks nil :type list)
+  (nlx-info-generated-p nil :type boolean))
 (defprinter (component :identity t)
   name
   #!+sb-show id
@@ -1274,7 +1275,8 @@
 ;;; continuation and the exit continuation's DEST. Instead of using
 ;;; the returned value being delivered directly to the exit
 ;;; continuation, it is delivered to our VALUE lvar. The original exit
-;;; lvar is the exit node's LVAR.
+;;; lvar is the exit node's LVAR; physenv analysis also makes it the
+;;; lvar of %NLX-ENTRY call.
 (defstruct (exit (:include valued-node)
 		 (:copier nil))
   ;; the ENTRY node that this is an exit for. If null, this is a

Index: physenvanal.lisp
===================================================================
RCS file: /cvsroot/sbcl/sbcl/src/compiler/physenvanal.lisp,v
retrieving revision 1.13
retrieving revision 1.14
diff -u -d -r1.13 -r1.14
--- physenvanal.lisp	30 Mar 2004 16:58:27 -0000	1.13
+++ physenvanal.lisp	1 May 2004 11:22:39 -0000	1.14
@@ -50,6 +50,7 @@
 	  (setf (functional-kind fun) nil)
           (delete-functional fun)))))
 
+  (setf (component-nlx-info-generated-p component) t)
   (values))
 
 ;;; This is to be called on a COMPONENT with top level LAMBDAs before
@@ -232,8 +233,8 @@
 ;;; knows what entry is being done.
 ;;;
 ;;; The link from the EXIT block to the entry stub is changed to be a
-;;; link to the component head. Similarly, the EXIT block is linked to
-;;; the component tail. This leaves the entry stub reachable, but
+;;; link from the component head. Similarly, the EXIT block is linked
+;;; to the component tail. This leaves the entry stub reachable, but
 ;;; makes the flow graph less confusing to flow analysis.
 ;;;
 ;;; If a CATCH or an UNWIND-protect, then we set the LEXENV for the
@@ -280,9 +281,10 @@
 ;;;    function reference. This will cause the escape function to
 ;;;    be deleted (although not removed from the DFO.)  The escape
 ;;;    function is no longer needed, and we don't want to emit code
-;;;    for it. We then also change the %NLX-ENTRY call to use the
-;;;    NLX continuation so that there will be a use to represent
-;;;    the NLX use.
+;;;    for it.
+;;; -- Change the %NLX-ENTRY call to use the NLX lvar so that 1) there
+;;;    will be a use to represent the NLX use; 2) make life easier for
+;;;    the stack analysis.
 (defun note-non-local-exit (env exit)
   (declare (type physenv env) (type exit exit))
   (let ((lvar (node-lvar exit))
@@ -300,11 +302,13 @@
 	(mapc (lambda (x)
 		(setf (node-derived-type x) *wild-type*))
 	      (leaf-refs exit-fun))
-	(substitute-leaf (find-constant info) exit-fun)
-	(let ((node (block-last (nlx-info-target info))))
-	  (delete-lvar-use node)
-          (aver (eq lvar (node-lvar exit)))
-	  (add-lvar-use node lvar)))))
+	(substitute-leaf (find-constant info) exit-fun))
+      (when lvar
+        (let ((node (block-last (nlx-info-target info))))
+          (unless (node-lvar node)
+            (aver (eq lvar (node-lvar exit)))
+            (setf (node-derived-type node) (lvar-derived-type lvar))
+            (add-lvar-use node lvar))))))
   (values))
 
 ;;; Iterate over the EXITs in COMPONENT, calling NOTE-NON-LOCAL-EXIT

Index: stack.lisp
===================================================================
RCS file: /cvsroot/sbcl/sbcl/src/compiler/stack.lisp,v
retrieving revision 1.12
retrieving revision 1.13
diff -u -d -r1.12 -r1.13
--- stack.lisp	13 Apr 2004 10:30:39 -0000	1.12
+++ stack.lisp	1 May 2004 11:22:39 -0000	1.13
@@ -1,7 +1,7 @@
 ;;;; This file implements the stack analysis phase in the compiler. We
 ;;;; do a graph walk to determine which unknown-values lvars are on
 ;;;; the stack at each point in the program, and then we insert
-;;;; cleanup code to pop off unused values.
+;;;; cleanup code to remove unused values.
 
 ;;;; This software is part of the SBCL system. See the README file for
 ;;;; more information.
@@ -41,129 +41,129 @@
       (setf (ir2-block-pushed 2block) (pushed))))
   (values))
 
-;;;; annotation graph walk
+;;;; Computation of live UVL sets
+(defun nle-block-nlx-info (block)
+  (let* ((start-node (block-start-node block))
+         (nlx-ref (ctran-next (node-next start-node)))
+         (nlx-info (constant-value (ref-leaf nlx-ref))))
+    nlx-info))
+(defun nle-block-entry-block (block)
+  (let* ((nlx-info (nle-block-nlx-info block))
+         (mess-up (cleanup-mess-up (nlx-info-cleanup nlx-info)))
+         (entry-block (node-block mess-up)))
+    entry-block))
 
 ;;; Add LVARs from LATE to EARLY; use EQ to check whether EARLY has
 ;;; been changed.
-(defun merge-stacks (early late)
+(defun merge-uvl-live-sets (early late)
   (declare (type list early late))
-  (cond ((null early) late)
-        ((null late) early)
-        ((tailp early late) late)
-        ((tailp late early) early)
-        ;; FIXME
-        (t (bug "Lexical unwinding of UVL stack is not implemented."))))
+  (dolist (e late early)
+    (pushnew e early)))
 
 ;;; Update information on stacks of unknown-values LVARs on the
 ;;; boundaries of BLOCK. Return true if the start stack has been
 ;;; changed.
-(defun stack-update (block)
+;;;
+;;; An LVAR is live at the end iff it is live at some of blocks, which
+;;; BLOCK can transfer control to. There are two kind of control
+;;; transfers: normal, expressed with BLOCK-SUCC, and NLX.
+(defun update-uvl-live-sets (block)
   (declare (type cblock block))
-  (declare (optimize (debug 3)))
   (let* ((2block (block-info block))
+         (original-start (ir2-block-start-stack 2block))
          (end (ir2-block-end-stack 2block))
-         (new-end end)
-         (cleanup (block-end-cleanup block))
-         (found-similar-p nil))
-    (declare (ignore #-nil cleanup))
+         (new-end end))
     (dolist (succ (block-succ block))
-      #+nil
-      (when (and (< block succ)
-                 (eq cleanup (block-end-cleanup succ)))
-        (setq found-similar-p t))
-      (setq new-end (merge-stacks new-end (ir2-block-start-stack (block-info succ)))))
-    (unless found-similar-p
-      (map-block-nlxes (lambda (nlx-info)
-                         (let* ((nle (nlx-info-target nlx-info))
-                                (nle-start-stack (ir2-block-start-stack
-                                                  (block-info nle)))
-                                (exit-lvar (nlx-info-lvar nlx-info)))
-                           (when (eq exit-lvar (car nle-start-stack))
-                             (pop nle-start-stack))
-                           (setq new-end (merge-stacks new-end
-                                                       nle-start-stack))))
-                       block))
+      (setq new-end (merge-uvl-live-sets new-end
+                                         (ir2-block-start-stack (block-info succ)))))
+    (map-block-nlxes (lambda (nlx-info)
+                       (let* ((nle (nlx-info-target nlx-info))
+                              (nle-start-stack (ir2-block-start-stack
+                                                (block-info nle)))
+                              (exit-lvar (nlx-info-lvar nlx-info))
+                              (next-stack (if exit-lvar
+                                              (remove exit-lvar nle-start-stack)
+                                              nle-start-stack)))
+                         (setq new-end (merge-uvl-live-sets
+                                        new-end next-stack))))
+                     block)
 
     (setf (ir2-block-end-stack 2block) new-end)
+
     (let ((start new-end))
-      (dolist (push (reverse (ir2-block-pushed 2block)))
-        (if (eq (car start) push)
-            (pop start)
-            (aver (not (member push start)))))
+      (setq start (set-difference start (ir2-block-pushed 2block)))
+      (setq start (merge-uvl-live-sets start (ir2-block-popped 2block)))
 
-      (dolist (pop (reverse (ir2-block-popped 2block)))
-        (push pop start))
+      ;; We cannot delete unused UVLs during NLX, so all UVLs live at
+      ;; ENTRY will be actually live at NLE.
+      (when (and (eq (component-head (block-component block))
+                     (first (block-pred block)))
+                 (not (bind-p (block-start-node block))))
+        (let* ((entry-block (nle-block-entry-block block))
+               (entry-stack (ir2-block-start-stack (block-info entry-block))))
+          (setq start (merge-uvl-live-sets start entry-stack))))
 
-      (cond ((equal-but-no-car-recursion start
-                                         (ir2-block-start-stack 2block))
+      (when *check-consistency*
+        (aver (subsetp original-start start)))
+      (cond ((subsetp start original-start)
              nil)
             (t
              (setf (ir2-block-start-stack 2block) start)
              t)))))
 
-;;; Do stack annotation for any values generators in Block that were
-;;; unreached by all walks (i.e. the lvar isn't live at the point that
-;;; it is generated.)  This will only happen when the values receiver cannot be
-;;; reached from this particular generator (due to an unconditional control
-;;; transfer.)
-;;;
-;;; What we do is push on the End-Stack all lvars in Pushed that
-;;; aren't already present in the End-Stack. When we find any pushed
-;;; lvar that isn't live, it must be the case that all lvars
-;;; pushed after (on top of) it aren't live.
-;;;
-;;; If we see a pushed lvar that is the LVAR of a tail call, then we
-;;; ignore it, since the tail call didn't actually push anything. The
-;;; tail call must always the last in the block.
-;;;
-;;; [This function also fixes End-Stack in NLEs.]
-(defun annotate-dead-values (block)
-  (declare (type cblock block))
+
+;;;; Ordering of live UVL stacks
+
+;;; Put UVLs on the start/end stacks of BLOCK in the right order. PRED
+;;; is a predecessor of BLOCK with already sorted stacks; because all
+;;; UVLs being live at the BLOCK start are live in PRED, we just need
+;;; to delete dead UVLs.
+(defun order-block-uvl-sets (block pred)
   (let* ((2block (block-info block))
-	 (stack (ir2-block-end-stack 2block))
-	 (last (block-last block))
-	 (tailp-lvar (if (node-tail-p last) (node-lvar last))))
-    (do ((pushes (ir2-block-pushed 2block) (rest pushes))
-	 (popping nil))
-	((null pushes))
-      (let ((push (first pushes)))
-	(cond ((member push stack)
-	       (aver (not popping)))
-	      ((eq push tailp-lvar)
-	       (aver (null (rest pushes))))
-	      (t
-	       (push push (ir2-block-end-stack 2block))
-	       (setq popping t))))))
+         (pred-end-stack (ir2-block-end-stack (block-info pred)))
+         (start (ir2-block-start-stack 2block))
+         (start-stack (loop for lvar in pred-end-stack
+                            when (memq lvar start)
+                            collect lvar))
+         (end (ir2-block-end-stack 2block)))
+    (when *check-consistency*
+      (aver (subsetp start start-stack)))
+    (setf (ir2-block-start-stack 2block) start-stack)
 
-  (values))
+    (let* ((last (block-last block))
+           (tailp-lvar (if (node-tail-p last) (node-lvar last)))
+           (end-stack start-stack))
+      (dolist (pop (ir2-block-popped 2block))
+        (aver (eq pop (car end-stack)))
+        (pop end-stack))
+      (dolist (push (ir2-block-pushed 2block))
+        (aver (not (memq push end-stack)))
+        (push push end-stack))
+      (aver (subsetp end end-stack))
+      (when (and tailp-lvar
+                 (eq (ir2-lvar-kind (lvar-info tailp-lvar)) :unknown))
+        (aver (eq tailp-lvar (first end-stack)))
+        (pop end-stack))
+      (setf (ir2-block-end-stack 2block) end-stack))))
 
-;;; For every NLE block push all LVARs that are live in its ENTRY to
-;;; its start stack. (We cannot pop unused LVARs on a control transfer
-;;; to an NLE block, so we must do it later.)
-(defun fix-nle-block-stacks (component)
-  (declare (type component component))
-  (dolist (block (block-succ (component-head component)))
-    (let ((start-node (block-start-node block)))
-      (unless (bind-p start-node)
-        (let* ((2block (block-info block))
-               (start-stack (block-start-stack 2block))
-               (nlx-ref (ctran-next (node-next start-node)))
-               (nlx-info (constant-value (ref-leaf nlx-ref)))
-               (mess-up (cleanup-mess-up (nlx-info-cleanup nlx-info)))
-               (entry-block (node-block mess-up))
-               (entry-stack (ir2-block-start-stack (block-info entry-block)))
-               (exit-lvar (nlx-info-lvar nlx-info)))
-          (when (and exit-lvar
-                     (eq exit-lvar (car start-stack)))
-            (when *check-consistency*
-              (aver (not (memq exit-lvar entry-stack))))
-            (push exit-lvar entry-stack))
-          (when *check-consistency*
-            (aver (subsetp start-stack entry-stack)))
-          (setf (ir2-block-start-stack 2block) entry-stack)
-          (setf (ir2-block-end-stack 2block) entry-stack)
-                                        ; ANNOTATE-DEAD-VALUES will do the rest
-          )))))
+(defun order-uvl-sets (component)
+  (clear-flags component)
+  (loop with head = (component-head component)
+        with repeat-p do
+        (setq repeat-p nil)
+        (do-blocks (block component)
+          (unless (block-flag block)
+            (let ((pred (find-if #'block-flag (block-pred block))))
+              (when (and (eq pred head)
+                         (not (bind-p (block-start-node block))))
+                (let ((entry (nle-block-entry-block block)))
+                  (setq pred (if (block-flag entry) entry nil))))
+              (cond (pred
+                     (setf (block-flag block) t)
+                     (order-block-uvl-sets block pred))
+                    (t
+                     (setq repeat-p t))))))
+        while repeat-p))
 
 ;;; This is called when we discover that the stack-top unknown-values
 ;;; lvar at the end of BLOCK1 is different from that at the start of
@@ -183,20 +183,38 @@
 (defun discard-unused-values (block1 block2)
   (declare (type cblock block1 block2))
   (let* ((block1-stack (ir2-block-end-stack (block-info block1)))
-	 (block2-stack (ir2-block-start-stack (block-info block2)))
-	 (last-popped (elt block1-stack
-			   (- (length block1-stack)
-			      (length block2-stack)
-			      1))))
-    (aver (tailp block2-stack block1-stack))
-
-    (let* ((block (insert-cleanup-code block1 block2
-				       (block-start-node block2)
-				       `(%pop-values ',last-popped)))
-	   (2block (make-ir2-block block)))
-      (setf (block-info block) 2block)
-      (add-to-emit-order 2block (block-info block1))
-      (ltn-analyze-belated-block block)))
+         (block2-stack (ir2-block-start-stack (block-info block2)))
+         (cleanup-code
+          (cond ((eq (car block1-stack) (car block2-stack))
+                 (binding* ((preserved-count (mismatch block1-stack block2-stack)
+                              :exit-if-null)
+                            (n-last-preserved (1- preserved-count))
+                            (nipped-count (- (length block1-stack)
+                                             (length block2-stack)))
+                            (n-last-nipped (+ n-last-preserved nipped-count)))
+                   (aver (equal (nthcdr (1+ n-last-nipped) block1-stack)
+                                (nthcdr preserved-count block2-stack)))
+                   (compiler-notify "%NIP-VALUES emitted")
+                   `(%nip-values ',(elt block1-stack n-last-nipped)
+                                 ',(elt block1-stack n-last-preserved)
+                                 ,@(loop for moved in block1-stack
+                                         repeat preserved-count
+                                         collect `',moved))))
+                (t
+                 (let* ((n-popped (- (length block1-stack)
+                                     (length block2-stack)))
+                       (last-popped (elt block1-stack (1- n-popped))))
+                   (when *check-consistency*
+                     (aver (equal block2-stack (nthcdr n-popped block1-stack))))
+                   `(%pop-values ',last-popped))))))
+    (when cleanup-code
+      (let* ((block (insert-cleanup-code block1 block2
+                                         (block-start-node block2)
+                                         cleanup-code))
+             (2block (make-ir2-block block)))
+        (setf (block-info block) 2block)
+        (add-to-emit-order 2block (block-info block1))
+        (ltn-analyze-belated-block block))))
 
   (values))
 
@@ -220,12 +238,6 @@
 ;;; received. This phase doesn't need to be run when Values-Receivers
 ;;; is null, i.e. there are no unknown-values lvars used across block
 ;;; boundaries.
-;;;
-;;; Do the backward graph walk, starting at each values receiver. We
-;;; ignore receivers that already have a non-null START-STACK. These
-;;; are nested values receivers that have already been reached on
-;;; another walk. We don't want to clobber that result with our null
-;;; initial stack.
 (defun stack-analyze (component)
   (declare (type component component))
   (let* ((2comp (component-info component))
@@ -235,25 +247,20 @@
     (dolist (block generators)
       (find-pushed-lvars block))
 
+    ;;; Compute sets of live UVLs
     (loop for did-something = nil
           do (do-blocks-backwards (block component)
-               (when (stack-update block)
+               (when (update-uvl-live-sets block)
                  (setq did-something t)))
           while did-something)
 
-    (when *check-consistency*
-      (dolist (block (block-succ (component-head component)))
-        (when (bind-p (block-start-node block))
-          (aver (null (ir2-block-start-stack (block-info block)))))))
-
-    (dolist (block generators)
-      (annotate-dead-values block))
+    (order-uvl-sets component)
 
     (do-blocks (block component)
-      (let ((top (car (ir2-block-end-stack (block-info block)))))
+      (let ((top (ir2-block-end-stack (block-info block))))
 	(dolist (succ (block-succ block))
 	  (when (and (block-start succ)
-		     (not (eq (car (ir2-block-start-stack (block-info succ)))
+		     (not (eq (ir2-block-start-stack (block-info succ))
 			      top)))
 	    (discard-unused-values block succ))))))