linux-toolchains.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Ian Rogers <irogers@google.com>
To: Mark Wielaard <mark@klomp.org>
Cc: Andi Kleen <andi@firstfloor.org>,
	linux-toolchains@vger.kernel.org,
	LKML <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Stephane Eranian <eranian@google.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Ingo Molnar <mingo@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	"Phillips, Kim" <kim.phillips@amd.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: [PATCH] Only add -fno-var-tracking-assignments workaround for old GCC versions.
Date: Sat, 10 Oct 2020 15:21:28 -0700	[thread overview]
Message-ID: <CAP-5=fUT-1-CR-KMMsrpzgw9b3nBooeY05=YU9XKa5enO9SK+A@mail.gmail.com> (raw)
In-Reply-To: <20201010220712.5352-1-mark@klomp.org>

On Sat, Oct 10, 2020 at 3:08 PM Mark Wielaard <mark@klomp.org> wrote:
>
> Some old GCC versions between 4.5.0 and 4.9.1 might miscompile code
> with -fvar-tracking-assingments (which is enabled by default with -g -O2).
> commit 2062afb4f added -fno-var-tracking-assignments unconditionally to
> work around this. But newer versions of GCC no longer have this bug, so
> only add it for versions of GCC before 5.0.
>
> Signed-off-by: Mark Wielaard <mark@klomp.org>

Acked-by: Ian Rogers <irogers@google.com>

Thanks,
Ian

> ---
>  Makefile | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/Makefile b/Makefile
> index f84d7e4ca0be..4f4a9416a87a 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -813,7 +813,9 @@ KBUILD_CFLAGS       += -ftrivial-auto-var-init=zero
>  KBUILD_CFLAGS  += -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
>  endif
>
> -DEBUG_CFLAGS   := $(call cc-option, -fno-var-tracking-assignments)
> +# Workaround https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61801
> +# for old versions of GCC.
> +DEBUG_CFLAGS   := $(call cc-ifversion, -lt, 0500, $(call cc-option, -fno-var-tracking-assignments))
>
>  ifdef CONFIG_DEBUG_INFO
>  ifdef CONFIG_DEBUG_INFO_SPLIT
> --
> 2.18.4
>

  parent reply	other threads:[~2020-10-10 22:57 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-06 13:17 Additional debug info to aid cacheline analysis Peter Zijlstra
2020-10-06 19:00 ` Arnaldo Carvalho de Melo
2020-10-08  5:58 ` Stephane Eranian
2020-10-08  7:02   ` Peter Zijlstra
2020-10-08  9:32     ` Mark Wielaard
2020-10-08 21:23       ` Andi Kleen
2020-10-10 20:58         ` Mark Wielaard
2020-10-10 21:51           ` Mark Wielaard
     [not found]             ` <20201010220712.5352-1-mark@klomp.org>
2020-10-10 22:21               ` Ian Rogers [this message]
2020-10-12 18:59                 ` [PATCH] Only add -fno-var-tracking-assignments workaround for old GCC versions Nick Desaulniers
2020-10-12 19:12                   ` Mark Wielaard
2020-10-14 15:31                     ` Sedat Dilek
2020-10-14 11:01                 ` Mark Wielaard
2020-10-14 15:17                   ` Andi Kleen
2020-10-17 12:01                   ` [PATCH V2] " Mark Wielaard
2020-10-19 19:30                     ` Nick Desaulniers
2020-10-20 15:27                     ` Masahiro Yamada
2020-10-10 22:33             ` [PATCH] " Mark Wielaard
2020-10-11 11:04           ` Additional debug info to aid cacheline analysis Segher Boessenkool
2020-10-11 12:15           ` Florian Weimer
2020-10-11 12:23             ` Mark Wielaard
2020-10-11 12:28               ` Florian Weimer
2020-10-30  5:26       ` Namhyung Kim
2020-10-30  9:16         ` Mark Wielaard
2020-10-30 10:10           ` Peter Zijlstra
2020-11-02  8:27             ` Masami Hiramatsu
2020-11-03  4:22               ` Namhyung Kim

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAP-5=fUT-1-CR-KMMsrpzgw9b3nBooeY05=YU9XKa5enO9SK+A@mail.gmail.com' \
    --to=irogers@google.com \
    --cc=acme@kernel.org \
    --cc=andi@firstfloor.org \
    --cc=eranian@google.com \
    --cc=jolsa@kernel.org \
    --cc=kim.phillips@amd.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-toolchains@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=mark@klomp.org \
    --cc=mhiramat@kernel.org \
    --cc=mingo@kernel.org \
    --cc=namhyung@kernel.org \
    --cc=peterz@infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).