From 90c8094aec494df062b383d439874b380cf03925 Mon Sep 17 00:00:00 2001
From: Andy Wingo <wingo@pobox.com>
Date: Sat, 22 Feb 2014 15:34:46 +0100
Subject: [PATCH] Avoid attempting to eta-reduce self-loops.

* module/language/cps/simplify.scm (compute-eta-reductions): Avoid
  trying to eta-reduce a jump-to-self, as in (let lp () (lp)).  This
  caused the compiler to hang.
---
 module/language/cps/simplify.scm | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/module/language/cps/simplify.scm b/module/language/cps/simplify.scm
index bd7909806..1733161bb 100644
--- a/module/language/cps/simplify.scm
+++ b/module/language/cps/simplify.scm
@@ -60,7 +60,7 @@
          (for-each visit-fun funs)
          (visit-term body term-k term-args))
         (($ $continue k src ($ $values args))
-         (when (equal? term-args args)
+         (when (and (equal? term-args args) (not (eq? k term-k)))
            (hashq-set! table term-k k)))
         (($ $continue k src (and fun ($ $fun)))
          (visit-fun fun))