From: Mark Wielaard Date: Sat, 17 Oct 2020 12:01:35 +0000 (+0200) Subject: kbuild: Only add -fno-var-tracking-assignments for old GCC versions X-Git-Tag: xarray-5.12~1146^2~1 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=121c5d08d53c;p=users%2Fwilly%2Fxarray.git kbuild: Only add -fno-var-tracking-assignments for old GCC versions 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 2062afb4f804 ("Fix gcc-4.9.0 miscompilation of load_balance() in scheduler") 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. This allows various tools such as a perf probe or gdb debuggers or systemtap to resolve variable locations using dwarf locations in more code. Signed-off-by: Mark Wielaard Acked-by: Ian Rogers Reviewed-by: Andi Kleen Signed-off-by: Masahiro Yamada --- diff --git a/Makefile b/Makefile index b76c4122c967..17a62e365a38 100644 --- a/Makefile +++ b/Makefile @@ -814,7 +814,11 @@ 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 for GCC versions < 5.0 +# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61801 +ifdef CONFIG_CC_IS_GCC +DEBUG_CFLAGS := $(call cc-ifversion, -lt, 0500, $(call cc-option, -fno-var-tracking-assignments)) +endif ifdef CONFIG_DEBUG_INFO