GNU bug report logs - #46540
28.0.50; Native-comp optimization bug

Previous Next

To add a comment to this bug, you must first unarchive it, by sending
a message to control AT debbugs.gnu.org, with unarchive 46540 in the body.
You can then email your comments to 46540 AT debbugs.gnu.org in the normal way.

Toggle the display of automated, internal messages from the tracker.

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Yu Han Quek <qythium <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 28.0.50; Native-comp optimization bug
Date: Tue, 16 Feb 2021 03:19:18 +0800

[Message part 1 (text/plain, inline)]

The following function gives an incorrect result when compiled natively
with comp-speed >= 2.

;; -*- lexical-binding: t; -*-

(defun native-comp-bug (body)
  (let ((x (car body))
        (y (cadr body)))
    (unless (and
             (natnump x)
             (natnump y)
             (<= x y))
      (error ""))
    x))

(native-comp-bug '(3 4))

;; Expected result: 3
;; Actual result: 0

The car of the argument is ignored and treated as 0.

This appears to be a minimal repro, manually shrunk from the original
function
discovered in rx.el (rx--translate-bounded-repetition).

If either lexical binding, natnump/inequality checks, or error form is
removed,
the function behaves as expected.

Setting comp-speed to 0 or 1 also causes the function to behave as
expected, but
setting it to 2 or 3 produces the error.

In GNU Emacs 28.0.50 (build 1, x86_64-apple-darwin20.2.0, NS appkit-2022.20
Version 11.1 (Build 20C69))
 of 2021-02-03 built on QYH2.local
Repository revision: e56c26d06f72b58acdc59c7e2958be9b691d3e78
Repository branch: master
System Description:  macOS 11.2.1

Configured using:
 'configure --with-ns --with-modules
 '--enable-locallisppath=/Library/Application
 Support/Emacs/${version}/site-lisp:/Library/Application
 Support/Emacs/site-lisp' --with-xwidgets --with-nativecomp
 --without-rsvg 'CFLAGS=-I/usr/local/opt/gcc/include -O2 -march=native'
 'LDFLAGS=-L/usr/local/opt/gcc/lib/gcc/10
 -L/usr/local/opt/libgccjit/lib/gcc/10
 -L/usr/local/opt/gcc/lib/gcc/10/gcc/x86_64-apple-darwin20/10.2.0
 -I/usr/local/opt/gcc/include -I/usr/local/opt/libgccjit/include''

Configured features:
ACL GIF GMP GNUTLS JPEG JSON LCMS2 LIBXML2 MODULES NATIVE_COMP NOTIFY
KQUEUE NS PDUMPER PNG THREADS TIFF TOOLKIT_SCROLL_BARS XWIDGETS ZLIB

Important settings:
  value of $LC_ALL: en_US.UTF-8
  value of $LC_CTYPE: UTF-8
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
rfc822 mml mml-sec epa derived epg epg-config gnus-util rmail
rmail-loaddefs auth-source eieio eieio-core eieio-loaddefs
password-cache json map text-property-search time-date mm-decode
mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader
sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils
term/xterm xterm comp comp-cstr warnings subr-x rx cl-seq cl-macs
cl-extra help-mode easymenu seq byte-opt gv cl-loaddefs cl-lib bytecomp
byte-compile cconv iso-transl tooltip eldoc electric uniquify ediff-hook
vc-hooks lisp-float-type mwheel term/ns-win ns-win ucs-normalize
mule-util term/common-win tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode elisp-mode lisp-mode
prog-mode register page tab-bar menu-bar rfn-eshadow isearch timer
select scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame minibuffer cl-generic cham georgian utf-8-lang
misc-lang vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms
cp51932 hebrew greek romanian slovak czech european ethiopic indian
cyrillic chinese composite charscript charprop case-table epa-hook
jka-cmpr-hook help simple abbrev obarray cl-preloaded nadvice button
loaddefs faces cus-face pcase macroexp files window text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote threads xwidget-internal kqueue cocoa
ns lcms2 multi-tty make-network-process nativecomp emacs)

Memory information:
((conses 16 79127 4281)
 (symbols 48 8088 1)
 (strings 32 20784 4357)
 (string-bytes 1 680668)
 (vectors 16 13082)
 (vector-slots 8 220094 8657)
 (floats 8 27 13)
 (intervals 56 213 0)
 (buffers 984 11))

[Message part 2 (text/html, inline)]

Message #8 received at 46540 <at> debbugs.gnu.org (full text, mbox):

From: Andrea Corallo <akrl <at> sdf.org>
To: Yu Han Quek <qythium <at> gmail.com>
Cc: 46540 <at> debbugs.gnu.org
Subject: Re: bug#46540: 28.0.50; Native-comp optimization bug
Date: Mon, 15 Feb 2021 20:08:54 +0000

Yu Han Quek <qythium <at> gmail.com> writes:

> The following function gives an incorrect result when compiled natively
> with comp-speed >= 2.
>
> ;; -*- lexical-binding: t; -*-
>
> (defun native-comp-bug (body)
>   (let ((x (car body))
>         (y (cadr body)))
>     (unless (and
>              (natnump x)
>              (natnump y)
>              (<= x y))
>       (error ""))
>     x))

Cool thanks for the reduced reproducer!

I'll have a in the coming days.

  Andrea

Message #11 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Andrea Corallo <akrl <at> sdf.org>
To: Andrea Corallo via "Bug reports for GNU Emacs, the Swiss army knife of
 text editors" <bug-gnu-emacs <at> gnu.org>
Cc: 46540 <at> debbugs.gnu.org, Yu Han Quek <qythium <at> gmail.com>
Subject: Re: bug#46540: 28.0.50; Native-comp optimization bug
Date: Tue, 16 Feb 2021 21:43:29 +0000

Andrea Corallo via "Bug reports for GNU Emacs, the Swiss army knife of
text editors" <bug-gnu-emacs <at> gnu.org> writes:

> Yu Han Quek <qythium <at> gmail.com> writes:
>
>> The following function gives an incorrect result when compiled natively
>> with comp-speed >= 2.
>>
>> ;; -*- lexical-binding: t; -*-
>>
>> (defun native-comp-bug (body)
>>   (let ((x (car body))
>>         (y (cadr body)))
>>     (unless (and
>>              (natnump x)
>>              (natnump y)
>>              (<= x y))
>>       (error ""))
>>     x))
>
> Cool thanks for the reduced reproducer!
>
> I'll have a in the coming days.
>
>   Andrea

Ok here a slightly simplified reproducer:

;; -*- lexical-binding: t; -*-
(defun native-comp-bug (x y)
  (if (and (natnump x)
           (natnump y)
           (<= x y))
      x
    (error "")))

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.

  Andrea

Message #17 received at 46540 <at> debbugs.gnu.org (full text, mbox):

From: Pip Cet <pipcet <at> gmail.com>
To: Andrea Corallo <akrl <at> sdf.org>
Cc: 46540 <at> debbugs.gnu.org, qythium <at> gmail.com
Subject: Re: bug#46540: 28.0.50; Native-comp optimization bug
Date: Wed, 17 Feb 2021 07:50:00 +0000

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).

Message #20 received at 46540 <at> debbugs.gnu.org (full text, mbox):

From: Andrea Corallo <akrl <at> sdf.org>
To: qythium <at> gmail.com
Cc: 46540 <at> debbugs.gnu.org, Pip Cet <pipcet <at> gmail.com>
Subject: Re: bug#46540: 28.0.50; Native-comp optimization bug
Date: Wed, 17 Feb 2021 21:11:53 +0000

Pip Cet <pipcet <at> gmail.com> writes:

> 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).

Yep, Pip spot on.  Small oversight from me... :D

1fe5994bcb should fix.

Yu Han Quek would you mind to confirm rx now works as excpected for you?

Thanks

  Andrea

Message #25 received at 46540-done <at> debbugs.gnu.org (full text, mbox):

From: Andrea Corallo <akrl <at> sdf.org>
To: Yu Han Quek <qythium <at> gmail.com>
Cc: 46540-done <at> debbugs.gnu.org
Subject: Re: bug#46540: 28.0.50; Native-comp optimization bug
Date: Thu, 18 Feb 2021 08:01:52 +0000

[re-adding the bug in Cc]

Yu Han Quek <qythium <at> gmail.com> writes:

[...]

>  Yep, Pip spot on.  Small oversight from me... :D
>
>  1fe5994bcb should fix.
>
>  Yu Han Quek would you mind to confirm rx now works as excpected for you?
>
>  Thanks
>
>    Andrea
>
> Thanks for the quick fix! I can confirm that the rx issue I ran into (rx (repeat 4 5 ?a)) now works as expected :)

Nice, closing then.

Thanks for reporting and testing!

  Andrea

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.