X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcompiler%2Fstack.lisp;h=1f4d546b1fab181bcda4865aae3be4393a2e55c1;hb=98a76d4426660876dec6649b1e228d2e5b47f579;hp=00dd5a6e30860a1ffa412cc5586c48d9a76ed791;hpb=7fd2eb4b1bc68e8aaec233c4a39bdfc40225bda2;p=sbcl.git

diff --git a/src/compiler/stack.lisp b/src/compiler/stack.lisp
index 00dd5a6..1f4d546 100644
--- a/src/compiler/stack.lisp
+++ b/src/compiler/stack.lisp
@@ -14,9 +14,9 @@
 
 (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
-;;; invariant that all pushes come after the last pop.
+;;; Scan through BLOCK looking for uses of :UNKNOWN continuations 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)
   (let* ((2block (block-info block))
 	 (popped (ir2-block-popped 2block))
@@ -43,44 +43,47 @@
 
 ;;;; 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.
+;;; Do a backward walk in the flow graph simulating the run-time stack
+;;; of unknown-values continuations 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 block. We
-;;; simulate the stack by popping off the unknown-values generated by this
-;;; block (if any) and pushing the continuations for values received by this
-;;; block. (The role of push and pop are interchanged because we are doing a
-;;; backward walk.)
+;;; BLOCK is the block that is currently being walked and STACK is the
+;;; stack of unknown-values continuations 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
+;;; 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 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 we run into a values generator whose continuation 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 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.
+;;; 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
+;;; 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.
+;;; 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.
+;;; 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.
+;;; 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)))
@@ -181,7 +184,7 @@
 ;;;; 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
+;;; RECEIVERS. Exits are excluded, since they don't drop through to the
 ;;; receiver.
 (defun find-values-generators (receivers)
   (declare (list receivers))
@@ -193,15 +196,17 @@
 	    (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 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.
 ;;;
-;;; 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))