X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcompiler%2Fstack.lisp;h=02839bf983c167fe144a95c822e98936f7d4402d;hb=1d46d379bb7a6424524b978f213ef69be5f1ad69;hp=b71a128a7112cd45a7bfbed6f26b65ab9f9e94bc;hpb=6053e7f804b430144bb09e2d107ad4ab3fb97db4;p=sbcl.git diff --git a/src/compiler/stack.lisp b/src/compiler/stack.lisp index b71a128..02839bf 100644 --- a/src/compiler/stack.lisp +++ b/src/compiler/stack.lisp @@ -43,73 +43,62 @@ ;;;; annotation graph walk -;;; Do a backward walk in the flow graph simulating the run-time stack -;;; of unknown-values lvars and annotating the blocks with the result. -;;; -;;; BLOCK is the block that is currently being walked and STACK is the -;;; stack of unknown-values lvars in effect immediately after -;;; block. We simulate the stack by popping off the unknown-values -;;; generated by this block (if any) and pushing the lvars for -;;; values received by this block. (The role of push and pop are -;;; interchanged because we are doing a backward walk.) -;;; -;;; If we run into a values generator whose lvar isn't on -;;; stack top, then the receiver hasn't yet been reached on any walk -;;; to this use. In this case, we ignore the push for now, counting on -;;; Annotate-Dead-Values to clean it up if we discover that it isn't -;;; reachable at all. -;;; -;;; If our final stack isn't empty, then we walk all the predecessor -;;; blocks that don't have all the lvars that we have on our -;;; START-STACK on their END-STACK. This is our termination condition -;;; for the graph walk. We put the test around the recursive call so -;;; that the initial call to this function will do something even -;;; though there isn't initially anything on the stack. -;;; -;;; We can use the tailp test, since the only time we want to bottom -;;; out with a non-empty stack is when we intersect with another path -;;; from the same top level call to this function that has more values -;;; receivers on that path. When we bottom out in this way, we are -;;; counting on DISCARD-UNUSED-VALUES doing its thing. -;;; -;;; When we do recurse, we check that predecessor's END-STACK is a -;;; subsequence of our START-STACK. There may be extra stuff on the -;;; top of our stack because the last path to the predecessor may have -;;; discarded some values that we use. There may be extra stuff on the -;;; bottom of our stack because this walk may be from a values -;;; receiver whose lifetime encloses that of the previous walk. -;;; -;;; If a predecessor block is the component head, then it must be the -;;; case that this is a NLX entry stub. If so, we just stop our walk, -;;; since the stack at the exit point doesn't have anything to do with -;;; our stack. -(defun stack-simulation-walk (block stack) - (declare (type cblock block) (list stack)) - (let ((2block (block-info block))) - (setf (ir2-block-end-stack 2block) stack) - (let ((new-stack stack)) - (dolist (push (reverse (ir2-block-pushed 2block))) - (if (eq (car new-stack) push) - (pop new-stack) - (aver (not (member push new-stack))))) +;;; Add LVARs from LATE to EARLY; use EQ to check whether EARLY has +;;; been changed. +(defun merge-stacks (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 (pop (reverse (ir2-block-popped 2block))) - (push pop new-stack)) +;;; 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) + (declare (type cblock block)) + (declare (optimize (debug 3))) + (let* ((2block (block-info block)) + (end (ir2-block-end-stack 2block)) + (new-end end) + (cleanup (block-end-cleanup block)) + (found-similar-p nil)) + (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)) - (setf (ir2-block-start-stack 2block) new-stack) + (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))))) - (when new-stack - (dolist (pred (block-pred block)) - (if (eq pred (component-head (block-component block))) - (aver (find block - (physenv-nlx-info (block-physenv block)) - :key #'nlx-info-target)) - (let ((pred-stack (ir2-block-end-stack (block-info pred)))) - (unless (tailp new-stack pred-stack) - (aver (search pred-stack new-stack)) - (stack-simulation-walk pred new-stack)))))))) + (dolist (pop (reverse (ir2-block-popped 2block))) + (push pop start)) - (values)) + (cond ((equal-but-no-car-recursion start + (ir2-block-start-stack 2block)) + 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 @@ -125,6 +114,8 @@ ;;; 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)) (let* ((2block (block-info block)) @@ -144,6 +135,34 @@ (setq popping t)))))) (values)) + +;;; 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 + ))))) ;;; 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 @@ -215,9 +234,16 @@ (dolist (block generators) (find-pushed-lvars block)) - (dolist (block receivers) - (unless (ir2-block-start-stack (block-info block)) - (stack-simulation-walk block ()))) + (loop for did-something = nil + do (do-blocks-backwards (block component) + (when (stack-update 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))