From: Nick Desaulniers <ndesaulniers@google.com>
To: David Laight <David.Laight@aculab.com>
Cc: "'Heiko Carstens'" <hca@linux.ibm.com>,
"Jens Axboe" <axboe@kernel.dk>,
"Stefan Haberland" <sth@linux.ibm.com>,
"Jan Höppner" <hoeppner@linux.ibm.com>,
"Peter Oberparleiter" <oberpar@linux.ibm.com>,
"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
llvm@lists.linux.dev
Subject: Re: [PATCH 1/1] s390/dasd: fix string length handling
Date: Mon, 28 Aug 2023 15:51:00 -0700 [thread overview]
Message-ID: <ZO0k1Par4i4FBCWF@google.com> (raw)
In-Reply-To: <f0419f6428ad404386ebca813dc1ec03@AcuMS.aculab.com>
On Mon, Aug 28, 2023 at 05:18:37PM +0000, David Laight wrote:
> From: Heiko Carstens
> > Sent: 28 August 2023 16:32
> > if (strlen(uid.vduit) > 0)
>
> Does the compiler know enough to optimise that brain-dead test?
>
For the purposes of skipping diagnostics, no; clang performs semantic
analysis BEFORE optimization (which is handled by LLVM). As such, clang
will produce diagnostics on dead code.
Partly because LLVM isn't very ergonomic at emitting diagnostics from
the backend, partly because Clang code owner and developers don't want
clang to emit diagnostics dependent on optimization level.
I disagree with my compatriots, and you can read more thoughts here:
https://discourse.llvm.org/t/rfc-improving-clangs-middle-and-back-end-diagnostics/69261?u=nickdesaulniers
next prev parent reply other threads:[~2023-08-28 22:51 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230828153142.2843753-1-hca@linux.ibm.com>
[not found] ` <20230828153142.2843753-2-hca@linux.ibm.com>
2023-08-28 22:46 ` [PATCH 1/1] s390/dasd: fix string length handling Nick Desaulniers
2023-08-28 22:53 ` Nick Desaulniers
2023-08-29 8:02 ` Heiko Carstens
2023-08-29 15:41 ` Nick Desaulniers
[not found] ` <f0419f6428ad404386ebca813dc1ec03@AcuMS.aculab.com>
2023-08-28 22:51 ` Nick Desaulniers [this message]
2023-08-29 7:48 ` Heiko Carstens
2023-08-29 8:32 ` David Laight
2023-08-29 15:39 ` Nick Desaulniers
2023-08-29 15:42 ` Nick Desaulniers
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