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From: "jsm28 at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/114469] gcc.dg/torture/bitint-64.c failure with -O2 -flto -std=c23 -fwrapv
Date: Mon, 25 Mar 2024 18:19:56 +0000	[thread overview]
Message-ID: <bug-114469-4-bLHV4myHYh@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-114469-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114469

--- Comment #1 from Joseph S. Myers <jsm28 at gcc dot gnu.org> ---
I'd expect _Atomic _BitInt(5) to follow the same ABI (regarding upper bits
being defined or not) as plain _BitInt(5), and any simplification needs to deal
with that.

(In principle for atomics with _BitInt with padding bits there are the same
concerns as for any types with padding bits - any compare-and-exchange loop
needs to succeed eventually when the underlying memory isn't being modified,
rather than failing in comparison of padding bits that might not have been
consistently loaded / preserved. My guess is this is unlikely to be a concern
in practice for _BitInt the way it is e.g. for x86 long double where the
padding bits only exist in memory and not in registers.)

  reply	other threads:[~2024-03-25 18:19 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-25 13:57 [Bug tree-optimization/114469] New: " jakub at gcc dot gnu.org
2024-03-25 18:19 ` jsm28 at gcc dot gnu.org [this message]
2024-03-27 18:39 ` [Bug tree-optimization/114469] " cvs-commit at gcc dot gnu.org

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