kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC

arch/arc/Makefile overrides -O2 with -O3. This is the only user of
ARCH_CFLAGS. There is no user of ARCH_CPPFLAGS or ARCH_AFLAGS.
My plan is to remove ARCH_{CPP,A,C}FLAGS after refactoring the ARC
Makefile.

Currently, ARC has no way to enable -Wmaybe-uninitialized because both
-O3 and -Os disable it. Enabling it will be useful for compile-testing.
This commit allows allmodconfig (, which defaults to -O2) to enable it.

Add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y to all the defconfig files
in arch/arc/configs/ in order to keep the current config settings.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/init/Kconfig b/init/Kconfig
index 149efd82447f..92118505dd33 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1209,14 +1209,22 @@ choice
         default CC_OPTIMIZE_FOR_PERFORMANCE
 
 config CC_OPTIMIZE_FOR_PERFORMANCE
-        bool "Optimize for performance"
+        bool "Optimize for performance (-O2)"
         help
           This is the default optimization level for the kernel, building
           with the "-O2" compiler flag for best performance and most
           helpful compile-time warnings.
 
+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
+          the kernel yet more for performance.
+
 config CC_OPTIMIZE_FOR_SIZE
-        bool "Optimize for size"
+        bool "Optimize for size (-Os)"
         imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED  # avoid false positives
         help
           Choosing this option will pass "-Os" to your compiler resulting