0.8.12.37:

[sbcl.git] / src / compiler / x86 / arith.lisp

diff --git a/src/compiler/x86/arith.lisp b/src/compiler/x86/arith.lisp
index 565a2e9..25d7091 100644 (file)
--- a/src/compiler/x86/arith.lisp
+++ b/src/compiler/x86/arith.lisp
@@ -176,9 +176,16 @@
                  (:translate ,translate)
                  (:generator ,untagged-penalty
                  (move r x)
-                 (inst ,op r y))))))
-
-  ;;(define-binop + 4 add)
+                 ,(if (eq translate 'logand)
+                      ;; for the -C/UNSIGNED=>UNSIGNED VOP, this case
+                      ;; is optimized away as an identity somewhere
+                      ;; along the lines.  However, this VOP is used in
+                      ;; -C/SIGNED=>UNSIGNED, below, when the
+                      ;; higher-level lisp code can't optimize away the
+                      ;; non-trivial identity.
+                      `(unless (= y #.(1- (ash 1 n-word-bits)))
+                         (inst ,op r y))
+                      `(inst ,op r y)))))))
   (define-binop - 4 sub)
   (define-binop logand 2 and)
   (define-binop logior 2 or)
@@ -249,7 +256,6 @@
           (move r x)
           (inst add r y)))))
 
-
 ;;;; Special logand cases: (logand signed unsigned) => unsigned
 
 (define-vop (fast-logand/signed-unsigned=>unsigned