GCC 10 appears to have changed -O2 in order to make compilation time faster when using -flto, seemingly at the expense of performance, in particular with regards to how the inliner works. Since -O3 these days shouldn't have the same set of bugs as 10 years ago, this commit defaults new kernel compiles to -O3 when using gcc >= 10. Cc: linux-kbuild@xxxxxxxxxxxxxxx Cc: x86@xxxxxxxxxx Cc: stable@xxxxxxxxxxxxxxx Cc: hjl.tools@xxxxxxxxx Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Jakub Jelinek <jakub@xxxxxxxxxx> Cc: Oleksandr Natalenko <oleksandr@xxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: David Laight <David.Laight@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx> --- Changes v1->v2: - [Oleksandr] Remove O3 dependency on ARC. init/Kconfig | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/init/Kconfig b/init/Kconfig index 9e22ee8fbd75..f76ec3ccc883 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1245,7 +1245,8 @@ config BOOT_CONFIG choice prompt "Compiler optimization level" - default CC_OPTIMIZE_FOR_PERFORMANCE + default CC_OPTIMIZE_FOR_PERFORMANCE_O3 if GCC_VERSION >= 100000 + default CC_OPTIMIZE_FOR_PERFORMANCE if (GCC_VERSION < 100000 || CC_IS_CLANG) config CC_OPTIMIZE_FOR_PERFORMANCE bool "Optimize for performance (-O2)" @@ -1256,7 +1257,6 @@ config CC_OPTIMIZE_FOR_PERFORMANCE config CC_OPTIMIZE_FOR_PERFORMANCE_O3 bool "Optimize more for performance (-O3)" - depends on ARC imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives help Choosing this option will pass "-O3" to your compiler to optimize -- 2.26.2
