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SubjectRe: [PATCH] x86: work around clang IAS bug referencing __force_order
On Sat 2020-08-22 11:51:56, Sedat Dilek wrote:
> On Sat, Aug 22, 2020 at 11:23 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >
> > On Sat, Aug 22, 2020 at 10:42 AM Segher Boessenkool
> > <segher@kernel.crashing.org> wrote:
> > >
> > > Hi Arvind,
> > >
> > > On Fri, Aug 21, 2020 at 11:55:52PM -0400, Arvind Sankar wrote:
> > > > Cc Segher.
> > > >
> > > > Segher, we were looking at gcc PR82602, where IRA could reorder volatile
> > > > asm's (reported on ARM). The fix was backported to gcc-6.
> > >
> > > I know ;-)
> > >
> > > > Do you know if
> > > > there is any reason the problem couldn't occur on x86 on older gcc
> > > > without the fix?
> > >
> > > No, I see no particular reason, at least GCC 5 seems vulnerable. (The
> > > GCC 5 release branch was closed at the time this bug report was made,
> > > already). There is no reason I see why it would work on x86 but fail
> > > elsewhere, either.
> > >
> >
> > [1] says:
> >
> > Current Minimal Requirements
> > ...
> > ====================== =============== ========================================
> > Program Minimal version Command to check the version
> > ====================== =============== ========================================
> > GNU C 4.9 gcc --version
> >
> > - Sedat -
> >
> > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/changes.rst#n32
>
> [ CC Miguel Ojeda (Compiler Attributes maintainer) ]
>
> There exist gcc-4.8 and gcc-4.9 for Debian/jessie where EOL was June
> 30, 2020 (see [1] and [2]).
>
> In the latest available version "4.9.2-10+deb8u1" I see no PR82602 was
> backported (see [3] and [4]).
>
> I am asking myself who is using such ancient compilers?
> Recently, I threw away GCC-8 from my Debian system.

I do have 4.9.2 on some systems. They work well, and are likely to compile
significantly faster than newer ones.

Please don't break them.

Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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