From: Nathan Chancellor <nathan@kernel.org>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: phoebe.pf.w@gmail.com, Arnd Bergmann <arnd@kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
llvm@lists.linux.dev
Subject: Re: [PATCH] power: reset: ltc2952: fix float conversion error
Date: Tue, 7 Dec 2021 12:21:40 -0700 [thread overview]
Message-ID: <Ya+0RKps7oAvdWl8@archlinux-ax161> (raw)
In-Reply-To: <CAKwvOdkxFrO0+WWqcQ9ZVHbT+TVpks1gE-SWG8yUF5U7E+HPHw@mail.gmail.com>
On Tue, Dec 07, 2021 at 11:16:31AM -0800, Nick Desaulniers wrote:
> (Minus most folks, plus Phoebe)
>
> On Tue, Dec 7, 2021 at 11:06 AM Nathan Chancellor <nathan@kernel.org> wrote:
> >
> > On Tue, Dec 07, 2021 at 10:41:24AM -0800, Nick Desaulniers wrote:
> > > On Sat, Dec 4, 2021 at 2:02 PM Arnd Bergmann <arnd@kernel.org> wrote:
> > > >
> > > > From: Arnd Bergmann <arnd@arndb.de>
> > > >
> > > > clang-14 does not like the way this driver converts a 'long double'
> > > > to an integer when the target architecture disables floating point
> > > > support:
> > > >
> > > > drivers/power/reset/ltc2952-poweroff.c:162:28: error: expression requires 'long double' type support, but target 'x86_64-unknown-linux' does not support it
> > > > data->wde_interval = 300L * 1E6L;
> > > > ^
> > > >
> > > > Turn this into pure integer math and make it more readable at the
> > > > same time using the NSEC_PER_MSEC macro instead.
> > > >
> > > > Fixes: 6647156c00cc ("power: reset: add LTC2952 poweroff driver")
> > > > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > >
> > > Thanks for the patch! The change in clang-14 (ToT) that triggered this
> > > has had another patch on top reverting these diagnostics.
> > > https://reviews.llvm.org/D114162
> >
> > I can still reproduce this failure on current ToT (33e3554ea33d) on
> > x86_64 allmodconfig; it seems like that patch only fixes it for 32-bit
> > x86.
>
> As a heads up Phoebe, in case there's any interest in doing something
> similar to https://reviews.llvm.org/D114162 but for 64b.
Phoebe pointed out on our issue tracker that GCC will error when long
double is used with -mno-80837 as well:
https://github.com/ClangBuiltLinux/linux/issues/1497#issuecomment-983245202
It just appears that GCC is able to avoid these errors in the particular
cases that the kernel triggers in clang:
https://github.com/ClangBuiltLinux/linux/issues/1497#issuecomment-983739365
Cheers,
Nathan
prev parent reply other threads:[~2021-12-07 19:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-04 22:01 [PATCH] power: reset: ltc2952: fix float conversion error Arnd Bergmann
2021-12-07 18:41 ` Nick Desaulniers
2021-12-07 19:00 ` Nick Desaulniers
2021-12-07 19:05 ` Nathan Chancellor
2021-12-07 19:16 ` Nick Desaulniers
2021-12-07 19:21 ` Nathan Chancellor [this message]
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