[Guile-commits] branch master updated: Make CSE more robust

[Andy Wingo]

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wingo pushed a commit to branch master
in repository guile.

The following commit(s) were added to refs/heads/master by this push:
     new fc13923  Make CSE more robust
fc13923 is described below

commit fc139231a67d97aaa29509e61c8f616c6b7f23ac
Author: Andy Wingo <wingo@pobox.com>
AuthorDate: Fri Jun 12 15:58:54 2020 +0200

    Make CSE more robust
    
    * module/language/cps/cse.scm (eliminate-common-subexpressions-in-fun):
      I think it's possible to get an orphan loop, with predecessors
      after successors in the original RPO.  Handle that here.
---
 module/language/cps/cse.scm | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/module/language/cps/cse.scm b/module/language/cps/cse.scm
index 5fe89ce..3cc48cd 100644
--- a/module/language/cps/cse.scm
+++ b/module/language/cps/cse.scm
@@ -551,7 +551,11 @@ false.  It could be that both true and false proofs are 
available."
                       (prune-successors analysis label (term-successors 
term))))
              ((trivial-intset preds)
               => (lambda (pred)
-                   (match (intmap-ref out pred)
+                   (match (and (< pred label) (intmap-ref out pred))
+                     (#f
+                      ;; Orphan loop; branch folding must have removed
+                      ;; entry.  Could still be alive though.
+                      (visit-term-normally))
                      (($ $kargs names' vars' ($ $continue _ _ ($ $values 
vals)))
                       ;; Substitute dominating definitions, and try to elide 
the
                       ;; predecessor entirely.
@@ -583,7 +587,7 @@ false.  It could be that both true and false proofs are 
available."
                          ;; those as well.
                          (add-auxiliary-definitions! pred vars substs 
term-key)))
                       (visit-term-normally))
-                     (_
+                     ((or ($ $kclause) ($ $kreceive))
                       (visit-term-normally)))))
              (else
               (visit-term-normally)))))))