Re: [PATCH] Only add -fno-var-tracking-assignments workaround for old GCC versions.

Ian Rogers
2020-10-10T23:00:47Z

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
>