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From: Sedat Dilek <sedat.dilek@gmail.com>
To: Mark Wielaard <mark@klomp.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
	Ian Rogers <irogers@google.com>, 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: Wed, 14 Oct 2020 17:31:39 +0200	[thread overview]
Message-ID: <CA+icZUUp3LWYc67E_XNRMQkUtVkmUAv2udZ0tJMvpeRCNnP8yA@mail.gmail.com> (raw)
In-Reply-To: <f3a1cd68a3f8f83e9e78a6ac1e5b74ceccbdc8be.camel@klomp.org>

On Mon, Oct 12, 2020 at 9:12 PM Mark Wielaard <mark@klomp.org> wrote:
>
> Hi,
>
> On Mon, 2020-10-12 at 11:59 -0700, Nick Desaulniers wrote:
> > On Sat, Oct 10, 2020 at 3:57 PM Ian Rogers <irogers@google.com>
> > wrote:
> > > On Sat, Oct 10, 2020 at 3:08 PM Mark Wielaard <mark@klomp.org>
> > > wrote:
> > > > -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))
> >
> > Should this be wrapped in: `ifdef CONFIG_CC_IS_GCC`/`endif`?
>
> I don't think so. It wasn't before. And call cc-option makes sure to
> only add the flag if the compiler supports it (clang doesn't and it
> also has a much higher version).
>

I am also in favour of `ifdef CONFIG_CC_IS_GCC` to clearly say this is
a GCC bug.

For the comment something like:

# Workaround for GCC version <= 5.0
# GCC Bug: <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61801>

Think of people grepping in the Linux source code for supported or
broken compiler (versions)...
As a reference see ClangBuiltLinux issue #427 "audit use of __GNUC__".
[2] says:
"There's also a ton of __GNUC_MINOR__ checks against unsupported GCC versions."

- Sedat -

[1] https://github.com/ClangBuiltLinux/linux/issues/427
[2] https://github.com/ClangBuiltLinux/linux/issues/427#issuecomment-700935241

  reply	other threads:[~2020-10-14 15:31 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               ` [PATCH] Only add -fno-var-tracking-assignments workaround for old GCC versions Ian Rogers
2020-10-12 18:59                 ` Nick Desaulniers
2020-10-12 19:12                   ` Mark Wielaard
2020-10-14 15:31                     ` Sedat Dilek [this message]
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

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