From: Mark Wielaard <mark@klomp.org>
To: linux-kernel@vger.kernel.org,
Masahiro Yamada <masahiroy@kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
linux-kbuild@vger.kernel.org
Cc: Ian Rogers <irogers@google.com>, Mark Wielaard <mark@klomp.org>,
linux-toolchains@vger.kernel.org,
Andi Kleen <andi@firstfloor.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Segher Boessenkool <segher@kernel.crashing.org>,
Florian Weimer <fw@deneb.enyo.de>
Subject: [PATCH] Only add -fno-var-tracking-assignments workaround for old GCC versions.
Date: Wed, 14 Oct 2020 13:01:32 +0200 [thread overview]
Message-ID: <20201014110132.2680-1-mark@klomp.org> (raw)
In-Reply-To: <CAP-5=fUT-1-CR-KMMsrpzgw9b3nBooeY05=YU9XKa5enO9SK+A@mail.gmail.com>
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>
Cc: linux-toolchains@vger.kernel.org
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Florian Weimer <fw@deneb.enyo.de>
---
Makefile | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/Makefile b/Makefile
index 51540b291738..8477fee5f309 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
next prev parent reply other threads:[~2020-10-14 11:02 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
2020-10-14 11:01 ` Mark Wielaard [this message]
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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