Different values computed in optimized vs. unopt code (random testing)

[Paul F. Dietz]

This was found by random testing on an SBCL x86 64 image built from source downloaded from github on 13/9/2017.

(defparameter *body*
  '(deposit-field
    (if (>= a 0)
 0
 131072)
    (byte 12 14)
    (logandc2 (* a c)
     (unwind-protect 5233637))))

(defun ftest3 ()
  (let ((fn1
  `(lambda (a c)
     (declare (type (integer -329826015068 198680020865) a))
     (declare (type (integer -25542480 21150532) c))
     (declare (optimize (safety 2) (debug 0) (space 0)
          (compilation-speed 1) (speed 2)))
     ,*body*))
 (fn2
  `(lambda (a c)
     ,*body*))
 (vals '(-25845520859 -20524970)))
    (values
     (apply (compile nil fn1) vals)
     (apply (compile nil fn2) vals))))

(ftest3) ==> 530478540240461834, 530478540240592906

The first value appears to be incorrect.

[Paul F. Dietz (paul-f-dietz)]

By the way, this does not occur in 1.3.21.

[Stas Boukarev (stassats)]

In 86dc287bb9343e454154ad7682636f47632bc348.

[Stas Boukarev (stassats)]

Rather eb26de5438e49a4d7b55d258fb8e4c5f15d8dfee.