tree 3e7286b299e940dac4fec5f82ac210b88e9b227d
parent 8402ee182c417a32d5e5a702f2fa2b01e76dc220
author Mark Wielaard <mark@klomp.org> 1602936095 +0200
committer Masahiro Yamada <masahiroy@kernel.org> 1603207733 +0900

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 <mark@klomp.org>
Acked-by: Ian Rogers <irogers@google.com>
Reviewed-by: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>