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From: "rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/110751] RISC-V: Suport undefined value that allows VSETVL PASS use TA/MA
Date: Thu, 20 Jul 2023 13:32:52 +0000 [thread overview]
Message-ID: <bug-110751-4-47ySVgS1rS@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-110751-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110751
--- Comment #14 from rguenther at suse dot de <rguenther at suse dot de> ---
On Thu, 20 Jul 2023, rsandifo at gcc dot gnu.org wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110751
>
> rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> changed:
>
> What |Removed |Added
> ----------------------------------------------------------------------------
> CC| |rsandifo at gcc dot gnu.org
>
> --- Comment #13 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
> I understand the concern with undefined values, since it then becomes less
> obvious whether e.g.:
>
> a = undef
> b = a == a
>
> is guaranteed to be true, or whether it reduces to:
>
> b = undef == undef
>
> which is presumably undef.
>
> But I don't think a null operand really helps. The same question would apply
> to:
>
> x = COND_LEN_ADD (a, b, null, len, bias)
> y = x == x
>
> vs.
>
> x1 = COND_LEN_ADD (a, b, null, len, bias)
> x2 = COND_LEN_ADD (a, b, null, len, bias)
> y = x1 == x2
>
> Do both of these ys evaluate to true, or is one or both be undefined?
>
> So if we're prepared to accept undefinedness, I'd prefer to have a ?proper?
> representation of it. We could probably adopt LLVM's semantics for undef.
>
> (SVE might have some uses for this too.)
Note I simply proposed 'NULL' as the "proper" representation of it.
That doesn't fix any of the semantic issues but I think neither does
any other representation ...
next prev parent reply other threads:[~2023-07-20 13:32 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-20 9:03 [Bug target/110751] New: " xuli1 at eswincomputing dot com
2023-07-20 9:10 ` [Bug target/110751] " juzhe.zhong at rivai dot ai
2023-07-20 9:30 ` rguenth at gcc dot gnu.org
2023-07-20 9:37 ` rguenth at gcc dot gnu.org
2023-07-20 9:58 ` kito at gcc dot gnu.org
2023-07-20 11:28 ` rguenther at suse dot de
2023-07-20 11:43 ` juzhe.zhong at rivai dot ai
2023-07-20 12:00 ` juzhe.zhong at rivai dot ai
2023-07-20 12:35 ` rguenther at suse dot de
2023-07-20 12:42 ` juzhe.zhong at rivai dot ai
2023-07-20 12:45 ` rguenther at suse dot de
2023-07-20 12:50 ` juzhe.zhong at rivai dot ai
2023-07-20 12:56 ` rguenther at suse dot de
2023-07-20 13:29 ` rsandifo at gcc dot gnu.org
2023-07-20 13:32 ` rguenther at suse dot de [this message]
2023-07-20 22:03 ` juzhe.zhong at rivai dot ai
2023-07-21 1:53 ` xuli1 at eswincomputing dot com
2023-07-21 6:17 ` rguenth at gcc dot gnu.org
2023-07-21 12:47 ` rsandifo at gcc dot gnu.org
2023-07-21 12:53 ` rguenth at gcc dot gnu.org
2023-07-21 13:23 ` rsandifo at gcc dot gnu.org
2023-07-24 6:20 ` rguenther at suse dot de
2023-07-25 7:05 ` juzhe.zhong at rivai dot ai
2023-09-12 11:44 ` juzhe.zhong at rivai dot ai
2023-09-12 14:24 ` rsandifo at gcc dot gnu.org
2023-09-12 14:53 ` juzhe.zhong at rivai dot ai
2023-09-12 15:59 ` rsandifo at gcc dot gnu.org
2023-09-12 16:21 ` juzhe.zhong at rivai dot ai
2023-09-12 16:27 ` juzhe.zhong at rivai dot ai
2023-09-12 16:31 ` juzhe.zhong at rivai dot ai
2023-09-12 22:44 ` juzhe.zhong at rivai dot ai
2023-09-13 7:56 ` rguenth at gcc dot gnu.org
2023-09-13 8:34 ` juzhe.zhong at rivai dot ai
2023-09-13 8:39 ` juzhe.zhong at rivai dot ai
2023-09-13 9:38 ` rguenth at gcc dot gnu.org
2023-09-13 9:39 ` rguenth at gcc dot gnu.org
2023-09-13 9:48 ` juzhe.zhong at rivai dot ai
2023-09-13 9:48 ` juzhe.zhong at rivai dot ai
2023-09-13 10:15 ` rguenther at suse dot de
2023-09-13 22:39 ` rsandifo at gcc dot gnu.org
2023-09-14 8:53 ` juzhe.zhong at rivai dot ai
2023-09-14 9:15 ` richard.sandiford at arm dot com
2023-09-20 16:27 ` cvs-commit at gcc dot gnu.org
2023-09-21 9:13 ` cvs-commit at gcc dot gnu.org
2023-09-21 9:28 ` juzhe.zhong at rivai dot ai
2023-09-22 7:31 ` xuli1 at eswincomputing dot com
2023-09-22 7:33 ` xuli1 at eswincomputing dot com
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