From: Segher Boessenkool <segher@kernel.crashing.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: kbuild test robot <lkp@intel.com>,
Nick Desaulniers <ndesaulniers@google.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
Paul Mackerras <paulus@samba.org>,
Nathan Chancellor <natechancellor@gmail.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH] powerpc: workaround clang codegen bug in dcbz
Date: Tue, 30 Jul 2019 12:07:28 -0500 [thread overview]
Message-ID: <20190730170728.GQ31406@gate.crashing.org> (raw)
In-Reply-To: <20190730161637.GP31406@gate.crashing.org>
On Tue, Jul 30, 2019 at 11:16:37AM -0500, Segher Boessenkool wrote:
> in_le32 and friends? Yeah, huh. If LLVM copies that to the stack as
> well, its (not byte reversing) read will be atomic just fine, so things
> will still work correctly.
>
> The things defined with DEF_MMIO_IN_D (instead of DEF_MMIO_IN_X) do not
> look like they will work correctly if an update form address is chosen,
> but that won't happen because the constraint is "m" instead of "m<>",
> making the %Un pretty useless (it will always be the empty string).
Btw, this is true since GCC 4.8; before 4.8, plain "m" *could* have an
automodify (autoinc, autodec, etc.) side effect. What is the minimum
GCC version required, these days?
https://gcc.gnu.org/PR44492
https://gcc.gnu.org/r161328
Segher
next prev parent reply other threads:[~2019-07-30 17:09 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-29 20:25 [PATCH] powerpc: workaround clang codegen bug in dcbz Nick Desaulniers
2019-07-29 20:32 ` Nathan Chancellor
2019-07-29 20:45 ` Nick Desaulniers
2019-07-29 20:47 ` Nathan Chancellor
2019-07-29 20:49 ` Nick Desaulniers
2019-07-29 21:52 ` Segher Boessenkool
2019-07-30 7:34 ` Arnd Bergmann
2019-07-30 11:17 ` Michael Ellerman
2019-08-09 18:21 ` [PATCH] powerpc: fix inline asm constraints for dcbz Nick Desaulniers
2019-08-09 18:28 ` Arnd Bergmann
2019-08-09 20:03 ` Christophe Leroy
2019-08-09 20:12 ` Arnd Bergmann
2019-08-09 22:03 ` Nick Desaulniers
2019-08-09 22:10 ` Segher Boessenkool
2019-08-09 22:00 ` Segher Boessenkool
2019-08-09 22:03 ` [PATCH v3] Revert "powerpc: slightly improve cache helpers" Nick Desaulniers
2019-08-10 9:09 ` Michael Ellerman
2019-08-09 21:55 ` [PATCH] powerpc: fix inline asm constraints for dcbz Segher Boessenkool
2019-08-09 20:36 ` Nathan Chancellor
2019-07-30 13:48 ` [PATCH] powerpc: workaround clang codegen bug in dcbz Segher Boessenkool
2019-07-30 14:30 ` Arnd Bergmann
2019-07-30 16:16 ` Segher Boessenkool
2019-07-30 17:07 ` Segher Boessenkool [this message]
2019-07-30 18:24 ` Arnd Bergmann
2019-07-30 18:24 ` Arnd Bergmann
2019-07-30 19:35 ` Segher Boessenkool
2019-07-30 5:31 ` Christophe Leroy
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