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From: "rsandifo at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/94899] Failure to optimize out add before compare with INT_MIN
Date: Fri, 01 May 2020 08:47:46 +0000 [thread overview]
Message-ID: <bug-94899-4-KjsmbXk9Ts@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-94899-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94899
rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |easyhack
Status|RESOLVED |NEW
Last reconfirmed| |2020-05-01
CC| |rsandifo at gcc dot gnu.org
Resolution|INVALID |---
Ever confirmed|0 |1
--- Comment #4 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
Reopening because...
(In reply to Andrew Pinski from comment #2)
> This is invalid as 0x80000000 is unsigned (C90/C++03) or long (C99/C++11) in
> type.
> Which means then overflow is not undefined but rather wrapping.
It's unsigned int for C99/C++11 too (see the different handling of
decimal-literals and other integer-literals in [lex.icon.type]).
This means that the result of the addition is also unsigned,
For the specific value of 0x80000000, the transformation is monotonic,
so the optimisation is valid and well-defined.
next prev parent reply other threads:[~2020-05-01 8:47 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-01 0:17 [Bug tree-optimization/94899] New: Failure to optimize out add before compare gabravier at gmail dot com
2020-05-01 1:30 ` [Bug tree-optimization/94899] Failure to optimize out add before compare with INT_MIN pinskia at gcc dot gnu.org
2020-05-01 1:37 ` pinskia at gcc dot gnu.org
2020-05-01 1:38 ` pinskia at gcc dot gnu.org
2020-05-01 8:47 ` rsandifo at gcc dot gnu.org [this message]
2022-06-21 10:22 ` cvs-commit at gcc dot gnu.org
2022-06-22 22:37 ` gabravier at gmail dot com
2023-02-17 20:46 ` gabravier at gmail dot com
2023-02-17 20:50 ` pinskia at gcc dot gnu.org
2023-05-17 21:31 ` pinskia at gcc dot gnu.org
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