From: Segher Boessenkool <segher@kernel.crashing.org>
To: Nadav Amit <namit@vmware.com>
Cc: Richard Biener <rguenther@suse.de>, Michael Matz <matz@suse.de>,
Borislav Petkov <bp@alien8.de>,
"gcc@gcc.gnu.org" <gcc@gcc.gnu.org>,
Ingo Molnar <mingo@redhat.com>,
LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Sam Ravnborg <sam@ravnborg.org>,
Alok Kataria <akataria@vmware.com>,
Christopher Li <sparse@chrisli.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"H. Peter Anvin" <hpa@zytor.com>, Jan Beulich <JBeulich@suse.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Juergen Gross <jgross@suse.com>,
Kate Stewart <kstewart@linuxfoundation.org>,
Kees Cook <keescook@chromium.org>,
"linux-sparse@vger.kernel.org" <linux-sparse@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Philippe Ombredanne <pombredanne@nexb.com>
Subject: Re: PROPOSAL: Extend inline asm syntax with size spec
Date: Wed, 10 Oct 2018 14:21:12 -0500 [thread overview]
Message-ID: <20181010192111.GD29268@gate.crashing.org> (raw)
In-Reply-To: <5ACDEDEA-0E42-45F2-BC80-B96EC2ABC01D@vmware.com>
Hi Nadav,
On Wed, Oct 10, 2018 at 04:31:41PM +0000, Nadav Amit wrote:
> at 7:53 AM, Segher Boessenkool <segher@kernel.crashing.org> wrote:
> > How does this look?
>
> It looks good to me in general. I have a couple of reservations, but I
> suspect you will not want to address them:
>
> 1. It is not backward compatible, requiring a C macro to wrap it, as the
> kernel might be built with different compilers.
How *could* it be backward compatible? There should be an error or at least
a warning if the compiler does not support this, in general.
For the kernel, the kernel already has plenty of infrastructure to support
this (compiler.h etc.) For other applications it is quite trivial, too.
> 2. It is specific to asm.
Yes, and that is on purpose.
> I do not have in mind another use case (excluding
> the __builtin_constant_p), but it would be nicer IMHO to have a builtin
> saying “ignore the cost of this statement” for the matter of optimizations.
That is a hundred or a thousand times more work to design and implement
(including testing etc.) I'm not going to do it, but feel free to try
yourself!
Segher
next prev parent reply other threads:[~2018-10-10 19:21 UTC|newest]
Thread overview: 85+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-03 21:30 [PATCH v9 00/10] x86: macrofying inline asm Nadav Amit
2018-10-03 21:30 ` [PATCH v9 02/10] Makefile: Prepare for using macros for " Nadav Amit
2018-11-06 18:57 ` Logan Gunthorpe
2018-11-06 19:18 ` Nadav Amit
2018-11-06 20:01 ` Logan Gunthorpe
2018-11-07 18:01 ` Nadav Amit
2018-11-07 18:53 ` Logan Gunthorpe
2018-11-07 18:56 ` Nadav Amit
2018-11-07 21:43 ` Logan Gunthorpe
2018-11-07 21:50 ` hpa
2018-11-08 6:18 ` Nadav Amit
2018-11-08 17:14 ` Logan Gunthorpe
2018-11-08 19:54 ` Nadav Amit
2018-11-08 20:00 ` Logan Gunthorpe
2018-11-08 20:18 ` Nadav Amit
2018-11-10 22:04 ` Nadav Amit
2018-11-13 4:56 ` Logan Gunthorpe
2018-10-03 21:30 ` [PATCH v9 03/10] x86: objtool: use asm macro for better compiler decisions Nadav Amit
2018-10-07 9:18 ` PROPOSAL: Extend inline asm syntax with size spec Borislav Petkov
2018-10-07 13:22 ` Segher Boessenkool
2018-10-07 14:13 ` Borislav Petkov
2018-10-07 14:13 ` Borislav Petkov
2018-10-07 15:14 ` Segher Boessenkool
2018-10-08 5:58 ` Ingo Molnar
2018-10-08 5:58 ` Ingo Molnar
2018-10-08 7:53 ` Segher Boessenkool
2018-10-07 15:53 ` Michael Matz
2018-10-08 6:13 ` Ingo Molnar
2018-10-08 8:18 ` Segher Boessenkool
2018-10-08 7:31 ` Segher Boessenkool
2018-10-08 9:07 ` Richard Biener
2018-10-08 10:02 ` Segher Boessenkool
2018-10-09 14:53 ` Segher Boessenkool
2018-10-10 6:35 ` Ingo Molnar
2018-10-10 7:12 ` Richard Biener
2018-10-10 7:22 ` Ingo Molnar
2018-10-10 8:03 ` Segher Boessenkool
2018-10-10 8:19 ` Borislav Petkov
2018-10-10 8:35 ` Richard Biener
2018-10-10 18:54 ` Segher Boessenkool
2018-10-10 19:14 ` Borislav Petkov
2018-10-13 19:33 ` Borislav Petkov
2018-10-13 21:14 ` Alexander Monakov
2018-10-13 21:30 ` Borislav Petkov
2018-10-25 10:24 ` Borislav Petkov
2018-10-25 10:24 ` Borislav Petkov
2018-10-31 12:55 ` Peter Zijlstra
2018-10-31 13:11 ` Peter Zijlstra
2018-10-31 16:31 ` Segher Boessenkool
2018-11-01 5:20 ` Joe Perches
2018-11-01 5:20 ` Joe Perches
2018-11-01 9:01 ` Peter Zijlstra
2018-11-01 9:20 ` Joe Perches
2018-11-01 9:20 ` Joe Perches
2018-11-01 11:15 ` Peter Zijlstra
2018-12-27 4:47 ` Masahiro Yamada
2018-10-10 19:14 ` Borislav Petkov
2018-10-10 8:19 ` Borislav Petkov
2018-10-10 10:29 ` Richard Biener
2018-10-10 7:53 ` Segher Boessenkool
2018-10-10 16:31 ` Nadav Amit
2018-10-10 19:21 ` Segher Boessenkool [this message]
2018-10-11 7:04 ` Richard Biener
2018-11-29 11:46 ` Masahiro Yamada
2018-11-29 12:25 ` Segher Boessenkool
2018-11-30 9:06 ` Boris Petkov via Virtualization
2018-11-30 9:06 ` Boris Petkov
2018-11-30 13:16 ` Segher Boessenkool
2018-12-10 8:16 ` Masahiro Yamada
2018-12-10 8:16 ` Masahiro Yamada
2018-11-29 13:07 ` Borislav Petkov via Virtualization
2018-11-29 13:09 ` Richard Biener
2018-11-29 13:16 ` Borislav Petkov
2018-11-29 13:24 ` Richard Biener
2018-11-29 13:16 ` Borislav Petkov via Virtualization
2018-11-29 11:46 ` Masahiro Yamada
2018-10-08 16:24 ` David Laight
2018-10-08 16:24 ` David Laight
2018-10-07 16:09 ` Nadav Amit
2018-10-07 16:13 ` [RESEND] " Nadav Amit
2018-10-07 16:46 ` Richard Biener
2018-10-07 19:06 ` Nadav Amit
2018-10-07 19:52 ` Jeff Law
2018-10-08 7:46 ` Richard Biener
2018-10-07 9:18 ` Borislav Petkov
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