0.8.16.25:

[sbcl.git] / src / compiler / copyprop.lisp

diff --git a/src/compiler/copyprop.lisp b/src/compiler/copyprop.lisp
index 41f886c..eefacbd 100644 (file)
--- a/src/compiler/copyprop.lisp
+++ b/src/compiler/copyprop.lisp
@@ -55,8 +55,8 @@
 ;;; The TN must be a :NORMAL TN. Other TNs might have hidden
 ;;; references or be otherwise bizarre.
 ;;;
-;;; A TN is also inelegible if it has interned name, policy is such
-;;; that we would dump it in the debug vars, and speed is not 3.
+;;; A TN is also inelegible if we want to preserve it to facilitate
+;;; debugging.
 ;;;
 ;;; The SCs of the TN's primitive types is a subset of the SCs of the
 ;;; copied TN. Moves between TNs of different primitive type SCs may
@@ -84,14 +84,22 @@
                                 (tn-primitive-type arg-tn)))
                       (let ((leaf (tn-leaf tn)))
                         (or (not leaf)
-                            (not (symbol-package (leaf-name leaf)))
-                            (policy (vop-node vop)
-                                    (or (= speed 3) (< debug 2)))))
+                             (and
+                              ;; Do we not care about preserving this this
+                              ;; TN for debugging?
+                              (or
+                               (not (symbol-package (leaf-debug-name leaf)))
+                               (policy (vop-node vop)
+                                       (or (= speed 3) (< debug 2))))
+                              ;; arguments of local functions have hidden write
+                              (not (and (lambda-var-p leaf)
+                                        (memq (functional-kind (lambda-var-home leaf))
+                                                   '(nil :optional)))))))
                       arg-tn)))))))
 
-;;; Init the sets in Block for copy propagation. To find Gen, we just
+;;; Init the sets in BLOCK for copy propagation. To find GEN, we just
 ;;; look for MOVE vops, and then see whether the result is a eligible
-;;; copy TN. To find Kill, we must look at all VOP results, seeing
+;;; copy TN. To find KILL, we must look at all VOP results, seeing
 ;;; whether any of the reads of the written TN are copies for eligible
 ;;; TNs.
 (defun init-copy-sets (block)
@@ -105,8 +113,9 @@
                     (when (tn-is-copy-of y)
                       (sset-adjoin y gen)
                       t)))
+        ;; WANTED: explanation of UNLESS above.
        (do ((res (vop-results vop) (tn-ref-across res)))
-           ((null res))
+           ((not res))
          (let ((res-tn (tn-ref-tn res)))
            (do ((read (tn-reads res-tn) (tn-ref-next read)))
                ((null read))
@@ -116,13 +125,12 @@
                    (when (tn-is-copy-of y)
                      (sset-delete y gen)
                      (sset-adjoin y kill))))))))))
-
     (setf (block-out block) (copy-sset gen))
     (setf (block-kill block) kill)
     (setf (block-gen block) gen))
   (values))
 
-;;; Do the flow analysis step for copy propagation on Block. We rely
+;;; Do the flow analysis step for copy propagation on BLOCK. We rely
 ;;; on OUT being initialized to GEN, and use SSET-UNION-OF-DIFFERENCE
 ;;; to incrementally build the union in OUT, rather than replacing OUT
 ;;; each time.
@@ -133,7 +141,9 @@
     (dolist (pred-block (rest pred))
       (sset-intersection in (block-out pred-block)))
     (setf (block-in block) in)
-    (sset-union-of-difference (block-out block) in (block-kill block))))
+    (sset-union-of-difference (block-out block)
+                             in
+                             (block-kill block))))
 
 (defevent copy-deleted-move "Copy propagation deleted a move.")