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From: Pip Cet <pipcet@gmail.com>
To: Andrea Corallo <akrl@sdf.org>
Cc: 46540@debbugs.gnu.org, qythium@gmail.com
Subject: bug#46540: 28.0.50; Native-comp optimization bug
Date: Wed, 17 Feb 2021 07:50:00 +0000	[thread overview]
Message-ID: <CAOqdjBc_-v61DJUoxuD6obANFmvU33Yg8o_PndVFeugj14dKNg@mail.gmail.com> (raw)
In-Reply-To: <xjfzh03r8n2.fsf@sdf.org>

On Tue, Feb 16, 2021 at 9:44 PM Andrea Corallo wrote:
> The following constrain insn clearly resolves in the wrong way:
>
> (assume #(mvar 79140560 0 (integer 0 0)) (<= #(mvar 79118120 0 (integer 0 *)) #(mvar 79118988 3 (integer 0 *))))
>
> Will come-up with a fix.

My guess is that this code in comp-cstr.el:

(defun comp-cstr-<= (dst old-dst src)
  "Constraint DST being <= than SRC.
SRC can be either a comp-cstr or an integer."
  (with-comp-cstr-accessors
    (let ((ext-range
           (if (integerp src)
               `((- . ,src))
             (when-let* ((range (range src))
                         (low (comp-cstr-smallest-in-range range))
                         (okay (integerp low)))
               `((- . ,low))))))
      (comp-cstr-set-cmp-range dst old-dst ext-range))))

should use comp-cstr-greatest-in-range rather than
comp-cstr-smallest-in-range. Same for comp-cstr-<. Analogous for
comp-cstr->, comp-cstr->=.

(If A's possible values are {3, 4, 5}, and B is <= A, we can only
conclude B <= 5, not that B <= 3, since A = 5, B = 5 is a solution to
the constraint problem).





  reply	other threads:[~2021-02-17  7:50 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-15 19:19 bug#46540: 28.0.50; Native-comp optimization bug Yu Han Quek
2021-02-15 20:08 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-02-16 21:43   ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-02-17  7:50     ` Pip Cet [this message]
2021-02-17 21:11       ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
     [not found]         ` <CAGCUw0iUhX4xJK=2LYYVDECV7qo7RtS_Z2JewyFLu3dLXD_tYg@mail.gmail.com>
2021-02-18  8:01           ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors

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