[Guile-commits] 07/19: Fix effects analysis bug for synthesized definitions at allocations

[Andy Wingo]

wingo pushed a commit to branch main
in repository guile.

commit e7e625b7731c29f1777dd670381ef374588c26d0
Author: Andy Wingo <wingo@pobox.com>
AuthorDate: Thu Jun 22 14:34:49 2023 +0200

    Fix effects analysis bug for synthesized definitions at allocations
    
    * module/language/cps/effects-analysis.scm (compute-known-allocations):
    For a primcall that allocates, sometimes we will synthesize auxiliary
    definitions as part of CSE, for example to indicate that if (cons x y)
    is bound to z, that a later call to (car z) should give x unless there
    might be an intervening set-car!.  We had a bug in which aux definitions
    attached to allocations were being incorrectly associated with the first
    operand.  Probably this is a bug in other contexts but it really starts
    to hit with the high-level constructors, e.g. `box`.
---
 module/language/cps/effects-analysis.scm | 1 +
 1 file changed, 1 insertion(+)

diff --git a/module/language/cps/effects-analysis.scm 
b/module/language/cps/effects-analysis.scm
index c6439cfd1..3e81c3eb4 100644
--- a/module/language/cps/effects-analysis.scm
+++ b/module/language/cps/effects-analysis.scm
@@ -268,6 +268,7 @@ loads from objects created at known allocation sites."
     (lambda (label fx out)
       (cond
        ((causes-all-effects? fx) out)
+       ((logtest fx &allocation) out)
        ((logtest fx (logior &read &write))
         (match (intmap-ref conts label)
           ;; Assume that instructions which cause a known set of effects