From: Robert Pluim <rpluim@gmail.com>
To: Eli Zaretskii <eliz@gnu.org>
Cc: eggert@cs.ucla.edu, Pip Cet <pipcet@gmail.com>, emacs-devel@gnu.org
Subject: Re: Floating-point constant folding in Emacs byte compiler
Date: Mon, 26 Mar 2018 11:39:25 +0200 [thread overview]
Message-ID: <87d0zr2n1u.fsf@gmail.com> (raw)
In-Reply-To: <83vadmgfbz.fsf@gnu.org> (Eli Zaretskii's message of "Sat, 24 Mar 2018 09:25:36 +0300")
Eli Zaretskii <eliz@gnu.org> writes:
>> From: Pip Cet <pipcet@gmail.com>
>> Date: Fri, 23 Mar 2018 20:52:52 +0000
>> Cc: Emacs development discussions <emacs-devel@gnu.org>
>>
>> Is this really specific to floating-point expressions, though?
>>
>> (byte-compile (lambda (x) (* #x10000 #x10000 #x10000 #x10000)))
>> #[(x) "À\207" [0] 1]
>>
>> (at least on this somewhat oudated version of Emacs). Note the 0 in
>> the constant vector, which hardcodes the <65-bit-ness of fixnums.
>>
>> I imagine that on a 32-bit version of emacs, (byte-compile (lambda (x)
>> (* #x10000 #x10000))) similarly produces a constant-zero function,
>
> The result depends on whether Emacs was build --with-wide-int. If it
> was, the result is #[(x) "\300\207" [4294967296] 1], if it wasn't, I
> get #[(x) "\300\207" [0] 1].
Hmm, would it be worthwhile to have Emacs signal overflow in such a
situation (perhaps controlled by a configuration variable) so we could
fix such issues?
Robert
next prev parent reply other threads:[~2018-03-26 9:39 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-22 23:04 Floating-point constant folding in Emacs byte compiler Paul Eggert
2018-03-23 1:26 ` Stefan Monnier
2018-03-23 5:22 ` Paul Eggert
2018-03-23 8:24 ` Eli Zaretskii
2018-03-23 20:00 ` Paul Eggert
2018-03-23 8:15 ` Eli Zaretskii
2018-03-23 20:52 ` Pip Cet
2018-03-24 6:25 ` Eli Zaretskii
2018-03-26 9:39 ` Robert Pluim [this message]
2018-03-26 15:13 ` Eli Zaretskii
2018-03-26 15:57 ` Robert Pluim
2018-03-26 16:02 ` Eli Zaretskii
2018-03-26 18:23 ` Pip Cet
2018-03-26 18:29 ` Eli Zaretskii
2018-03-27 0:28 ` Paul Eggert
2018-03-27 23:28 ` Paul Eggert
2018-03-30 16:26 ` Pip Cet
2018-03-30 16:31 ` Noam Postavsky
2018-03-30 16:39 ` Paul Eggert
2018-04-02 10:56 ` Pip Cet
2018-04-02 11:22 ` Eli Zaretskii
2018-04-02 11:42 ` Pip Cet
2018-04-02 12:50 ` Eli Zaretskii
2018-04-02 14:50 ` Stefan Monnier
2018-04-02 15:02 ` Pip Cet
2018-04-02 12:57 ` Noam Postavsky
2018-04-02 13:30 ` Eli Zaretskii
2018-04-02 14:48 ` Stefan Monnier
2018-04-02 19:20 ` Paul Eggert
2018-04-02 19:39 ` Pip Cet
2018-04-02 19:58 ` Eli Zaretskii
2018-04-02 20:55 ` Pip Cet
[not found] ` <<83y3i568i0.fsf@gnu.org>
2018-04-02 13:37 ` Drew Adams
2018-04-02 14:05 ` Eli Zaretskii
2018-04-02 14:54 ` Pip Cet
2018-04-02 15:02 ` Drew Adams
2018-03-26 17:52 ` Stefan Monnier
2018-03-26 18:30 ` Eli Zaretskii
2018-03-27 0:08 ` Paul Eggert
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