Substitute constants with modular equivalents more safely

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

diff --git a/src/compiler/srctran.lisp b/src/compiler/srctran.lisp
index 5858da9..f6369e6 100644 (file)
--- a/src/compiler/srctran.lisp
+++ b/src/compiler/srctran.lisp
@@ -3060,7 +3060,10 @@
                                        (ldb (byte width 0) constant-value))))
                    (unless (= constant-value new-value)
                      (change-ref-leaf node (make-constant new-value))
-                     (setf (lvar-%derived-type (node-lvar node)) (make-values-type :required (list (ctype-of new-value))))
+                     (let ((lvar (node-lvar node)))
+                       (setf (lvar-%derived-type lvar)
+                             (and (lvar-has-single-use-p lvar)
+                                  (make-values-type :required (list (ctype-of new-value))))))
                      (setf (block-reoptimize (node-block node)) t)
                      (reoptimize-component (node-component node) :maybe)
                      (return-from cut-node t))))