On Sat, Oct 10, 2020 at 10:58:36PM +0200, Mark Wielaard wrote:
> Yes, that would work. I don't know what the lowest supported GCC
> version is, but technically it was definitely fixed in 4.10.0, 4.8.4
> and 4.9.2. And various distros would probably have backported the
> fix. But checking for 5.0+ would certainly give you a good version.
>
> How about the attached?
Looks like vger just throws away emails with patch attachements. How
odd. I'll try sending it as reply to this message with git-send-email.
Cheers,
Mark
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 <[email protected]>
---
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