From: "Mattias Engdegård" <mattiase@acm.org>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: Paul Eggert <eggert@cs.ucla.edu>,
Andrea Corallo <andrea_corallo@yahoo.it>,
42147@debbugs.gnu.org
Subject: bug#42147: 28.0.50; pure vs side-effect-free, missing optimizations?
Date: Fri, 3 Jul 2020 20:43:57 +0200 [thread overview]
Message-ID: <DCA1D4B6-C03B-42DA-B2D2-5576774C730F@acm.org> (raw)
In-Reply-To: <E1D62559-E2E4-4576-B495-F83363EB981C@acm.org>
[-- Attachment #1: Type: text/plain, Size: 25 bytes --]
> patch attached
Now.
[-- Attachment #2: 0001-Relax-portable-number-check-in-byte-compiler-bug-421.patch --]
[-- Type: application/octet-stream, Size: 4540 bytes --]
From 7b0a5329706a6c73e49b5e3b464543f8ba94f21d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mattias=20Engdeg=C3=A5rd?= <mattiase@acm.org>
Date: Fri, 3 Jul 2020 20:13:50 +0200
Subject: [PATCH] Relax portable number check in byte compiler (bug#42147)
With bignums, the set of representable integers is no longer
platform-dependent, and since we use nothing but IEEE754 64-bit
floats, all numbers are now portable. Take advantage of this fact
to simplify constant-folding in the byte compiler, allowing it to
be applied more widely.
* lisp/emacs-lisp/byte-opt.el (byte-opt--portable-max)
(byte-opt--portable-min, byte-opt--portable-numberp): Remove.
(byte-opt--arith-reduce, byte-optimize-minus, byte-optimize-1+)
(byte-optimize-1-): Simplify: any number will do, and if N is a
number, then so are -N, N+1 and N-1.
---
lisp/emacs-lisp/byte-opt.el | 39 +++++++++----------------------------
1 file changed, 9 insertions(+), 30 deletions(-)
diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el
index 12bde8faf3..bf9e6a728a 100644
--- a/lisp/emacs-lisp/byte-opt.el
+++ b/lisp/emacs-lisp/byte-opt.el
@@ -672,36 +672,18 @@ byte-optimize-associative-math
(apply (car form) constants))
form)))
-;; Portable Emacs integers fall in this range.
-(defconst byte-opt--portable-max #x1fffffff)
-(defconst byte-opt--portable-min (- -1 byte-opt--portable-max))
-
-;; True if N is a number that works the same on all Emacs platforms.
-;; Portable Emacs fixnums are exactly representable as floats on all
-;; Emacs platforms, and (except for -0.0) any floating-point number
-;; that equals one of these integers must be the same on all
-;; platforms. Although other floating-point numbers such as 0.5 are
-;; also portable, it can be tricky to characterize them portably so
-;; they are not optimized.
-(defun byte-opt--portable-numberp (n)
- (and (numberp n)
- (<= byte-opt--portable-min n byte-opt--portable-max)
- (= n (floor n))
- (not (and (floatp n) (zerop n)
- (condition-case () (< (/ n) 0) (error))))))
-
-;; Use OP to reduce any leading prefix of portable numbers in the list
-;; (cons ACCUM ARGS) down to a single portable number, and return the
+;; Use OP to reduce any leading prefix of constant numbers in the list
+;; (cons ACCUM ARGS) down to a single number, and return the
;; resulting list A of arguments. The idea is that applying OP to A
;; is equivalent to (but likely more efficient than) applying OP to
;; (cons ACCUM ARGS), on any Emacs platform. Do not make any special
;; provision for (- X) or (/ X); for example, it is the caller’s
;; responsibility that (- 1 0) should not be "optimized" to (- 1).
(defun byte-opt--arith-reduce (op accum args)
- (when (byte-opt--portable-numberp accum)
+ (when (numberp accum)
(let (accum1)
- (while (and (byte-opt--portable-numberp (car args))
- (byte-opt--portable-numberp
+ (while (and (numberp (car args))
+ (numberp
(setq accum1 (condition-case ()
(funcall op accum (car args))
(error))))
@@ -746,12 +728,11 @@ byte-optimize-minus
;; (- x -1) --> (1+ x)
((equal (cdr args) '(-1))
(list '1+ (car args)))
- ;; (- n) -> -n, where n and -n are portable numbers.
+ ;; (- n) -> -n, where n and -n are constant numbers.
;; This must be done separately since byte-opt--arith-reduce
;; is not applied to (- n).
((and (null (cdr args))
- (byte-opt--portable-numberp (car args))
- (byte-opt--portable-numberp (- (car args))))
+ (numberp (car args)))
(- (car args)))
;; not further optimized
((equal args (cdr form)) form)
@@ -761,8 +742,7 @@ byte-optimize-1+
(let ((args (cdr form)))
(when (null (cdr args))
(let ((n (car args)))
- (when (and (byte-opt--portable-numberp n)
- (byte-opt--portable-numberp (1+ n)))
+ (when (numberp n)
(setq form (1+ n))))))
form)
@@ -770,8 +750,7 @@ byte-optimize-1-
(let ((args (cdr form)))
(when (null (cdr args))
(let ((n (car args)))
- (when (and (byte-opt--portable-numberp n)
- (byte-opt--portable-numberp (1- n)))
+ (when (numberp n)
(setq form (1- n))))))
form)
--
2.21.1 (Apple Git-122.3)
next prev parent reply other threads:[~2020-07-03 18:43 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1583748933.1069307.1593556032592.ref@mail.yahoo.com>
2020-06-30 22:27 ` bug#42147: 28.0.50; pure vs side-effect-free, missing optimizations? Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-06-30 23:14 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-01 12:46 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-01 12:44 ` Mattias Engdegård
2020-07-01 16:08 ` Mattias Engdegård
2020-07-01 21:31 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-02 10:26 ` Mattias Engdegård
2020-07-02 10:59 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-02 12:46 ` Mattias Engdegård
2020-07-02 13:56 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-02 14:51 ` Mattias Engdegård
2020-07-02 15:32 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-02 15:49 ` Stefan Monnier
2020-07-02 18:01 ` Mattias Engdegård
2020-07-02 18:55 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-02 19:38 ` Stefan Monnier
2020-07-02 20:09 ` Paul Eggert
2020-07-03 9:32 ` Mattias Engdegård
2020-07-03 13:39 ` bug#42147: Hash-consing bignums (was: bug#42147: 28.0.50; pure vs side-effect-free, missing optimizations?) Stefan Monnier
2020-07-02 20:31 ` bug#42147: 28.0.50; pure vs side-effect-free, missing optimizations? Paul Eggert
2020-07-02 21:41 ` Stefan Monnier
2020-07-02 23:16 ` Paul Eggert
2020-07-03 8:32 ` Mattias Engdegård
2020-07-03 13:11 ` Stefan Monnier
2020-07-03 18:35 ` Mattias Engdegård
2020-07-03 18:43 ` Mattias Engdegård [this message]
2020-07-03 19:05 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-04 14:58 ` Mattias Engdegård
2020-07-04 15:06 ` Stefan Monnier
2020-07-04 16:13 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-05 13:00 ` Mattias Engdegård
2020-07-05 13:16 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-06 17:20 ` Mattias Engdegård
2020-07-06 21:23 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-07 15:54 ` Mattias Engdegård
2020-07-07 16:24 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-07 16:55 ` Mattias Engdegård
2020-07-07 17:42 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-08 19:14 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-08 21:25 ` Mattias Engdegård
2020-07-08 22:19 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-09 10:20 ` Mattias Engdegård
2020-07-09 12:47 ` Stefan Monnier
2020-07-09 12:57 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-09 14:35 ` Stefan Monnier
2020-07-09 15:19 ` Paul Eggert
2020-07-09 15:37 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-05 15:26 ` Mattias Engdegård
2020-07-03 18:31 ` Paul Eggert
2020-07-03 18:47 ` Mattias Engdegård
2020-07-04 15:57 ` Paul Eggert
2020-07-04 16:15 ` Eli Zaretskii
2020-07-04 16:27 ` Paul Eggert
2020-07-04 16:33 ` Stefan Monnier
2020-07-04 16:44 ` Mattias Engdegård
2020-07-04 17:00 ` Paul Eggert
2020-07-04 18:37 ` Pip Cet
2020-07-04 21:05 ` Stefan Monnier
2020-07-04 22:25 ` Pip Cet
2020-07-05 2:38 ` Eli Zaretskii
2020-07-05 8:28 ` Paul Eggert
2020-07-05 8:39 ` Andreas Schwab
2020-07-05 14:47 ` Eli Zaretskii
2020-07-05 15:30 ` Stefan Monnier
2020-07-06 0:14 ` Paul Eggert
2020-07-05 15:11 ` Stefan Monnier
2020-07-06 0:10 ` Paul Eggert
2020-07-05 9:56 ` Paul Eggert
2020-07-05 10:03 ` Andrea Corallo via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-07-05 23:57 ` Paul Eggert
2020-07-04 19:01 ` Mattias Engdegård
2020-07-04 17:10 ` Eli Zaretskii
2020-07-04 19:26 ` Paul Eggert
2020-07-02 19:09 ` Philipp Stephani
2020-07-03 9:25 ` Mattias Engdegård
2020-07-25 17:09 ` Philipp Stephani
2020-07-25 18:10 ` Stefan Monnier
2020-07-25 20:03 ` Philipp Stephani
2020-07-25 20:07 ` Stefan Monnier
2020-07-25 20:11 ` Philipp Stephani
2020-07-25 21:00 ` Mattias Engdegård
2020-07-25 21:29 ` Stefan Monnier
2020-07-25 21:39 ` Philipp Stephani
2020-07-25 22:27 ` Stefan Monnier
2020-07-29 12:53 ` Philipp Stephani
2020-07-29 14:28 ` Stefan Monnier
2020-07-25 21:54 ` Mattias Engdegård
2020-07-25 22:30 ` Stefan Monnier
2020-07-26 9:05 ` Mattias Engdegård
2020-07-29 16:03 ` Mattias Engdegård
2020-07-29 20:39 ` Stefan Monnier
2020-08-03 15:07 ` Mattias Engdegård
2020-08-10 13:39 ` Philipp Stephani
2020-08-10 22:07 ` Stefan Monnier
2020-08-10 13:42 ` Philipp Stephani
2020-08-10 22:10 ` Stefan Monnier
2020-07-29 13:10 ` Philipp Stephani
2020-07-25 21:09 ` Stefan Monnier
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