X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcompiler%2Fstack.lisp;h=b71a128a7112cd45a7bfbed6f26b65ab9f9e94bc;hb=c3699db2053ff3b5ac6a98d4431c3789496002d8;hp=f04e92cf8f8de96830056ecdc897826e98e936b8;hpb=5ec8d0c1c8b7939818b75118b472fac1af554f9a;p=sbcl.git diff --git a/src/compiler/stack.lisp b/src/compiler/stack.lisp index f04e92c..b71a128 100644 --- a/src/compiler/stack.lisp +++ b/src/compiler/stack.lisp @@ -1,6 +1,6 @@ ;;;; This file implements the stack analysis phase in the compiler. We -;;;; do a graph walk to determine which unknown-values continuations -;;;; are on the stack at each point in the program, and then we insert +;;;; 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. ;;;; This software is part of the SBCL system. See the README file for @@ -14,29 +14,29 @@ (in-package "SB!C") -;;; Scan through Block looking for uses of :Unknown continuations that have -;;; their Dest outside of the block. We do some checking to verify the +;;; Scan through BLOCK looking for uses of :UNKNOWN lvars that have +;;; their DEST outside of the block. We do some checking to verify the ;;; invariant that all pushes come after the last pop. -(defun find-pushed-continuations (block) +(defun find-pushed-lvars (block) (let* ((2block (block-info block)) (popped (ir2-block-popped 2block)) (last-pop (if popped - (continuation-dest (car (last popped))) + (lvar-dest (car (last popped))) nil))) (collect ((pushed)) (let ((saw-last nil)) - (do-nodes (node cont block) + (do-nodes (node lvar block) (when (eq node last-pop) (setq saw-last t)) - (let ((dest (continuation-dest cont)) - (2cont (continuation-info cont))) - (when (and dest - (not (eq (node-block dest) block)) - 2cont - (eq (ir2-continuation-kind 2cont) :unknown)) - (aver (or saw-last (not last-pop))) - (pushed cont))))) + (when lvar + (let ((dest (lvar-dest lvar)) + (2lvar (lvar-info lvar))) + (when (and (not (eq (node-block dest) block)) + 2lvar + (eq (ir2-lvar-kind 2lvar) :unknown)) + (aver (or saw-last (not last-pop))) + (pushed lvar)))))) (setf (ir2-block-pushed 2block) (pushed)))) (values)) @@ -44,24 +44,23 @@ ;;;; annotation graph walk ;;; Do a backward walk in the flow graph simulating the run-time stack -;;; of unknown-values continuations and annotating the blocks with the -;;; result. +;;; 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 continuations in effect immediately after +;;; 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 continuations for +;;; 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 continuation isn't on +;;; 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 continuations that we have on our +;;; 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 @@ -113,32 +112,32 @@ (values)) ;;; Do stack annotation for any values generators in Block that were -;;; unreached by all walks (i.e. the continuation isn't live at the point that +;;; 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 continuations in Pushed that +;;; 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 -;;; continuation that isn't live, it must be the case that all continuations +;;; 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 continuation that is the CONT 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. +;;; 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. (defun annotate-dead-values (block) (declare (type cblock block)) (let* ((2block (block-info block)) (stack (ir2-block-end-stack 2block)) (last (block-last block)) - (tailp-cont (if (node-tail-p last) (node-cont last)))) + (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-cont) + ((eq push tailp-lvar) (aver (null (rest pushes)))) (t (push push (ir2-block-end-stack 2block)) @@ -147,20 +146,20 @@ (values)) ;;; This is called when we discover that the stack-top unknown-values -;;; continuation at the end of BLOCK1 is different from that at the -;;; start of BLOCK2 (its successor). +;;; lvar at the end of BLOCK1 is different from that at the start of +;;; BLOCK2 (its successor). ;;; ;;; We insert a call to a funny function in a new cleanup block ;;; introduced between BLOCK1 and BLOCK2. Since control analysis and ;;; LTN have already run, we must do make an IR2 block, then do -;;; ADD-TO-EMIT-ORDER and LTN-ANALYZE-BELATED-BLOCK on the new block. -;;; The new block is inserted after BLOCK1 in the emit order. +;;; ADD-TO-EMIT-ORDER and LTN-ANALYZE-BELATED-BLOCK on the new +;;; block. The new block is inserted after BLOCK1 in the emit order. ;;; ;;; If the control transfer between BLOCK1 and BLOCK2 represents a -;;; tail-recursive return (:DELETED IR2-continuation) or a non-local -;;; exit, then the cleanup code will never actually be executed. It -;;; doesn't seem to be worth the risk of trying to optimize this, -;;; since this rarely happens and wastes only space. +;;; tail-recursive return or a non-local exit, then the cleanup code +;;; will never actually be executed. It doesn't seem to be worth the +;;; risk of trying to optimize this, since this rarely happens and +;;; wastes only space. (defun discard-unused-values (block1 block2) (declare (type cblock block1 block2)) (let* ((block1-stack (ir2-block-end-stack (block-info block1))) @@ -172,7 +171,7 @@ (aver (tailp block2-stack block1-stack)) (let* ((block (insert-cleanup-code block1 block2 - (continuation-next (block-start block2)) + (block-start-node block2) `(%pop-values ',last-popped))) (2block (make-ir2-block block))) (setf (block-info block) 2block) @@ -183,9 +182,9 @@ ;;;; stack analysis -;;; Return a list of all the blocks containing genuine uses of one of the -;;; Receivers. Exits are excluded, since they don't drop through to the -;;; receiver. +;;; Return a list of all the blocks containing genuine uses of one of +;;; the RECEIVERS. Exits are excluded, since they don't drop through +;;; to the receiver. (defun find-values-generators (receivers) (declare (list receivers)) (collect ((res nil adjoin)) @@ -196,15 +195,17 @@ (res (node-block use)))))) (res))) -;;; Analyze the use of unknown-values continuations in Component, inserting -;;; cleanup code to discard values that are generated but never received. This -;;; phase doesn't need to be run when Values-Receivers is null, i.e. there are -;;; no unknown-values continuations used across block boundaries. +;;; Analyze the use of unknown-values lvars in COMPONENT, inserting +;;; cleanup code to discard values that are generated but never +;;; 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. +;;; 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)) @@ -212,7 +213,7 @@ (generators (find-values-generators receivers))) (dolist (block generators) - (find-pushed-continuations block)) + (find-pushed-lvars block)) (dolist (block receivers) (unless (ir2-block-start-stack (block-info block))