From: Sam James <sam@gentoo.org>
To: Paul Eggert <eggert@cs.ucla.edu>
Cc: arnold@skeeve.com, Gnulib bugs <bug-gnulib@gnu.org>,
concord@gentoo.org, bug-gawk@gnu.org
Subject: Re: Clang-built Gawk 5.2.1 regex oddity
Date: Tue, 3 Jan 2023 02:14:38 +0000 [thread overview]
Message-ID: <F4F78F36-49A9-4FB0-BF95-1984AF1FB6D1@gentoo.org> (raw)
In-Reply-To: <1cdb3d41-d675-cca1-7498-c3840f2ee8ad@cs.ucla.edu>
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> On 2 Jan 2023, at 06:10, Paul Eggert <eggert@cs.ucla.edu> wrote:
>
> This is a serious bug in Clang: it generates incorrect machine code.
>
> [snip]
>
> My guess is that Clang got confused because dfaerror is declared _Noreturn, so Clang mistakenly assumed that dfawarn is also _Noreturn, which it is not.
>
> I worked around the Clang bug by installed the attached patch into Gnulib. Please give it a try with Gawk.
Confirmed this mitigates the problem. I had to apply it manually to support/ as I couldn't immediately see how to sync gnulib myself, but that's no big deal.
>
> Incorrect code generation is a serious bug in Clang; can you please report it to the Clang folks? I am considering using a bigger hammer, and doing this:
>
Kenton's done this at https://github.com/llvm/llvm-project/issues/59792 now.
> #define _Noreturn /*empty*/
>
> whenever Clang is used, until the bug is fixed.
>
maskray's analysis so far at https://github.com/llvm/llvm-project/issues/59792#issuecomment-1369314436 agrees with yours, which would mean
this is likely a good idea.
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next prev parent reply other threads:[~2023-01-03 2:15 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20221230000119.hyui6umnspuyzqum@bubbles>
[not found] ` <202212300913.2BU9DV6V030160@freefriends.org>
[not found] ` <6DADB0FC-87EE-4028-91DF-C93A968A8982@gentoo.org>
2023-01-01 19:06 ` Clang-built Gawk 5.2.1 regex oddity arnold
2023-01-02 6:10 ` Paul Eggert
2023-01-03 2:14 ` Sam James [this message]
2023-01-03 2:43 ` Sam James
2023-01-05 23:06 ` Arsen Arsenović
2023-01-06 12:21 ` arnold
2023-01-13 7:03 ` Sam James
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