master: Speed up looking in the ctype-list-hash-set

The branch "master" has been updated in SBCL:
       via  ed2340f71ac49df95e0fe4fd201f3ac5a0e3c13b (commit)
      from  1285374c8c7ae0538d70803fae11c9f627cfb3ad (commit)

- Log -----------------------------------------------------------------
commit ed2340f71ac49df95e0fe4fd201f3ac5a0e3c13b
Author: Douglas Katzman <[email protected]>
Date:   Fri Jul 31 03:13:59 2026 +0000

    Speed up looking in the ctype-list-hash-set
    
    In a particular compile-file, this hashset grew to have a maximum probe
    sequence length of 14, and with 2 million lookups, it was a performance
    bottleneck. A better hash mixer cut the max PSL down to 7.
---
 src/code/type-class.lisp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/code/type-class.lisp b/src/code/type-class.lisp
index 2699471d9..7e4b6b952 100644
--- a/src/code/type-class.lisp
+++ b/src/code/type-class.lisp
@@ -623,6 +623,12 @@
         do (setq res (logxor (ash res -1) (type-%bits type)))
         ;; This returns a positive number so that it can be passed to MIX
         finally (return (ldb (byte (1- ctype-hash-size) 0) res))))
+(defun mix-hash-ctype-list (types)
+  (declare (optimize (speed 3) (safety 0)))
+  (loop with res of-type (and sb-xc:fixnum unsigned-byte) = 0
+        for type in types
+        do (setq res (mix (type-hash-value type) res))
+        finally (return (ldb (byte (1- ctype-hash-size) 0) res))))
 
 (defun hash-ctype-set (types) ; ctype list hashed order-insensitively
   (let ((hash (type-%bits (car types)))
@@ -643,7 +649,7 @@
   (and (= (length a) (length b)) (every (lambda (x) (memq x b)) a)))
 
 (define-load-time-global *ctype-list-hashset*
-  (make-hashset 32 #'list-elts-eq #'hash-ctype-list :weakness t :synchronized t))
+  (make-hashset 32 #'list-elts-eq #'mix-hash-ctype-list :weakness t :synchronized t))
 (define-load-time-global *ctype-set-hashset*
   (make-hashset 32 #'ctype-set= #'hash-ctype-set :weakness t :synchronized t))
 

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