[PATCH 2/3] kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC

Masahiro Yamada
2019-08-20T17:10:26Z

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>
---

Makefile | 10 ++++++----
arch/arc/Makefile | 8 --------
arch/arc/configs/axs101_defconfig | 1 +
arch/arc/configs/axs103_defconfig | 1 +
arch/arc/configs/axs103_smp_defconfig | 1 +
arch/arc/configs/haps_hs_defconfig | 1 +
arch/arc/configs/haps_hs_smp_defconfig | 1 +
arch/arc/configs/hsdk_defconfig | 1 +
arch/arc/configs/nps_defconfig | 1 +
arch/arc/configs/nsim_700_defconfig | 1 +
arch/arc/configs/nsim_hs_defconfig | 1 +
arch/arc/configs/nsim_hs_smp_defconfig | 1 +
arch/arc/configs/nsimosci_defconfig | 1 +
arch/arc/configs/nsimosci_hs_defconfig | 1 +
arch/arc/configs/nsimosci_hs_smp_defconfig | 1 +
arch/arc/configs/tb10x_defconfig | 1 +
arch/arc/configs/vdk_hs38_defconfig | 1 +
arch/arc/configs/vdk_hs38_smp_defconfig | 1 +
init/Kconfig | 12 ++++++++++--
19 files changed, 32 insertions(+), 14 deletions(-)

diff --git a/Makefile b/Makefile
index bc55f366677d..891e47da503f 100644
--- a/Makefile
+++ b/Makefile
@@ -716,10 +716,12 @@ KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation)
KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow)
KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)

-ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
-KBUILD_CFLAGS += -Os
-else
-KBUILD_CFLAGS += -O2
+ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE
+KBUILD_CFLAGS += -O2
+else ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3
+KBUILD_CFLAGS += -O3
+else ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
+KBUILD_CFLAGS += -Os
endif

ifdef CONFIG_CC_DISABLE_WARN_MAYBE_UNINITIALIZED
diff --git a/arch/arc/Makefile b/arch/arc/Makefile
index ee6d1184c2b1..f1c44cccf8d6 100644
--- a/arch/arc/Makefile
+++ b/arch/arc/Makefile
@@ -48,14 +48,6 @@ endif
cfi := $(call as-instr,.cfi_startproc\n.cfi_endproc,-DARC_DW2_UNWIND_AS_CFI)
cflags-$(CONFIG_ARC_DW2_UNWIND) += -fasynchronous-unwind-tables $(cfi)

-ifndef CONFIG_CC_OPTIMIZE_FOR_SIZE
-# Generic build system uses -O2, we want -O3
-# Note: No need to add to cflags-y as that happens anyways
-#
-# Disable the false maybe-uninitialized warings gcc spits out at -O3
-ARCH_CFLAGS += -O3 $(call cc-disable-warning,maybe-uninitialized,)
-endif
-
# small data is default for elf32 tool-chain. If not usable, disable it
# This also allows repurposing GP as scratch reg to gcc reg allocator
disable_small_data := y
diff --git a/arch/arc/configs/axs101_defconfig b/arch/arc/configs/axs101_defconfig
index e31a8ebc3ecc..0016149f9583 100644
--- a/arch/arc/configs/axs101_defconfig
+++ b/arch/arc/configs/axs101_defconfig
@@ -9,6 +9,7 @@ CONFIG_NAMESPACES=y
# CONFIG_UTS_NS is not set
# CONFIG_PID_NS is not set
CONFIG_BLK_DEV_INITRD=y
+CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y
CONFIG_EMBEDDED=y
CONFIG_PERF_EVENTS=y
# CONFIG_VM_EVENT_COUNTERS is not set
diff --git a/arch/arc/configs/axs103_defconfig b/arch/arc/configs/axs103_defconfig
index e0e8567f0d75..5b031582a1cf 100644
--- a/arch/arc/configs/axs103_defconfig
+++ b/arch/arc/configs/axs103_defconfig
@@ -9,6 +9,7 @@ CONFIG_NAMESPACES=y
# CONFIG_UTS_NS is not set
# CONFIG_PID_NS is not set
CONFIG_BLK_DEV_INITRD=y
+CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y
CONFIG_EMBEDDED=y
CONFIG_PERF_EVENTS=y
# CONFIG_VM_EVENT_COUNTERS is not set
diff --git a/arch/arc/configs/axs103_smp_defconfig b/arch/arc/configs/axs103_smp_defconfig
index fcbc952bc75b..d4eec39e0112 100644
--- a/arch/arc/configs/axs103_smp_defconfig
+++ b/arch/arc/configs/axs103_smp_defconfig
@@ -9,6 +9,7 @@ CONFIG_NAMESPACES=y
# CONFIG_UTS_NS is not set
# CONFIG_PID_NS is not set
CONFIG_BLK_DEV_INITRD=y
+CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y
CONFIG_EMBEDDED=y
CONFIG_PERF_EVENTS=y
# CONFIG_VM_EVENT_COUNTERS is not set
diff --git a/arch/arc/configs/haps_hs_defconfig b/arch/arc/configs/haps_hs_defconfig
index 436f2135bdc1..47ff8a97e42d 100644
--- a/arch/arc/configs/haps_hs_defconfig
+++ b/arch/arc/configs/haps_hs_defconfig
@@ -10,6 +10,7 @@ CONFIG_NAMESPACES=y
# CONFIG_UTS_NS is not set
# CONFIG_PID_NS is not set
CONFIG_BLK_DEV_INITRD=y
+CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y
CONFIG_EXPERT=y
CONFIG_PERF_EVENTS=y
# CONFIG_COMPAT_BRK is not set
diff --git a/arch/arc/configs/haps_hs_smp_defconfig b/arch/arc/configs/haps_hs_smp_defconfig
index 33a787c375e2..9685fd5f57a4 100644
--- a/arch/arc/configs/haps_hs_smp_defconfig
+++ b/arch/arc/configs/haps_hs_smp_defconfig
@@ -10,6 +10,7 @@ CONFIG_NAMESPACES=y
# CONFIG_UTS_NS is not set
# CONFIG_PID_NS is not set
CONFIG_BLK_DEV_INITRD=y
+CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y
CONFIG_EMBEDDED=y
CONFIG_PERF_EVENTS=y
# CONFIG_VM_EVENT_COUNTERS is not set
diff --git a/arch/arc/configs/hsdk_defconfig b/arch/arc/configs/hsdk_defconfig
index 403125d9c9a3..9b9a74444ce2 100644
--- a/arch/arc/configs/hsdk_defconfig
+++ b/arch/arc/configs/hsdk_defconfig
@@ -9,6 +9,7 @@ CONFIG_NAMESPACES=y
# CONFIG_PID_NS is not set
CONFIG_BLK_DEV_INITRD=y
CONFIG_BLK_DEV_RAM=y
+CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y
CONFIG_EMBEDDED=y
CONFIG_PERF_EVENTS=y
# CONFIG_VM_EVENT_COUNTERS is not set
diff --git a/arch/arc/configs/nps_defconfig b/arch/arc/configs/nps_defconfig
index f0a077c00efa..5978d4d7d5b0 100644
--- a/arch/arc/configs/nps_defconfig
+++ b/arch/arc/configs/nps_defconfig
@@ -6,6 +6,7 @@ CONFIG_HIGH_RES_TIMERS=y
CONFIG_IKCONFIG=y
CONFIG_IKCONFIG_PROC=y
CONFIG_BLK_DEV_INITRD=y
+CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y
CONFIG_SYSCTL_SYSCALL=y
# CONFIG_EPOLL is not set
# CONFIG_SIGNALFD is not set
diff --git a/arch/arc/configs/nsim_700_defconfig b/arch/arc/configs/nsim_700_defconfig
index de398c7b10b3..2b9b11474640 100644
--- a/arch/arc/configs/nsim_700_defconfig
+++ b/arch/arc/configs/nsim_700_defconfig
@@ -10,6 +10,7 @@ CONFIG_NAMESPACES=y
# CONFIG_UTS_NS is not set
# CONFIG_PID_NS is not set
CONFIG_BLK_DEV_INITRD=y
+CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y
CONFIG_KALLSYMS_ALL=y
CONFIG_EMBEDDED=y
CONFIG_PERF_EVENTS=y
diff --git a/arch/arc/configs/nsim_hs_defconfig b/arch/arc/configs/nsim_hs_defconfig
index 2dbd34a9ff07..bab3dd255841 100644
--- a/arch/arc/configs/nsim_hs_defconfig
+++ b/arch/arc/configs/nsim_hs_defconfig
@@ -10,6 +10,7 @@ CONFIG_NAMESPACES=y
# CONFIG_UTS_NS is not set
# CONFIG_PID_NS is not set
CONFIG_BLK_DEV_INITRD=y
+CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y
CONFIG_KALLSYMS_ALL=y
CONFIG_EMBEDDED=y
CONFIG_PERF_EVENTS=y
diff --git a/arch/arc/configs/nsim_hs_smp_defconfig b/arch/arc/configs/nsim_hs_smp_defconfig
index c7135f1e2583..90d2d50fb8dc 100644
--- a/arch/arc/configs/nsim_hs_smp_defconfig
+++ b/arch/arc/configs/nsim_hs_smp_defconfig
@@ -8,6 +8,7 @@ CONFIG_NAMESPACES=y
# CONFIG_UTS_NS is not set
# CONFIG_PID_NS is not set
CONFIG_BLK_DEV_INITRD=y
+CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y
CONFIG_KALLSYMS_ALL=y
CONFIG_EMBEDDED=y
CONFIG_PERF_EVENTS=y
diff --git a/arch/arc/configs/nsimosci_defconfig b/arch/arc/configs/nsimosci_defconfig
index 385a71d3c478..5dd470b6609e 100644
--- a/arch/arc/configs/nsimosci_defconfig
+++ b/arch/arc/configs/nsimosci_defconfig
@@ -10,6 +10,7 @@ CONFIG_NAMESPACES=y
# CONFIG_UTS_NS is not set
# CONFIG_PID_NS is not set
CONFIG_BLK_DEV_INITRD=y
+CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y
CONFIG_KALLSYMS_ALL=y
CONFIG_EMBEDDED=y
CONFIG_PERF_EVENTS=y
diff --git a/arch/arc/configs/nsimosci_hs_defconfig b/arch/arc/configs/nsimosci_hs_defconfig
index 248a2c3bdc12..3532e86f7bff 100644
--- a/arch/arc/configs/nsimosci_hs_defconfig
+++ b/arch/arc/configs/nsimosci_hs_defconfig
@@ -10,6 +10,7 @@ CONFIG_NAMESPACES=y
# CONFIG_UTS_NS is not set
# CONFIG_PID_NS is not set
CONFIG_BLK_DEV_INITRD=y
+CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y
CONFIG_KALLSYMS_ALL=y
CONFIG_EMBEDDED=y
CONFIG_PERF_EVENTS=y
diff --git a/arch/arc/configs/nsimosci_hs_smp_defconfig b/arch/arc/configs/nsimosci_hs_smp_defconfig
index 1a4bc7b660fb..d90448bee064 100644
--- a/arch/arc/configs/nsimosci_hs_smp_defconfig
+++ b/arch/arc/configs/nsimosci_hs_smp_defconfig
@@ -8,6 +8,7 @@ CONFIG_IKCONFIG_PROC=y
# CONFIG_UTS_NS is not set
# CONFIG_PID_NS is not set
CONFIG_BLK_DEV_INITRD=y
+CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y
CONFIG_PERF_EVENTS=y
# CONFIG_COMPAT_BRK is not set
CONFIG_KPROBES=y
diff --git a/arch/arc/configs/tb10x_defconfig b/arch/arc/configs/tb10x_defconfig
index dc739bd093e3..3a138f8c7299 100644
--- a/arch/arc/configs/tb10x_defconfig
+++ b/arch/arc/configs/tb10x_defconfig
@@ -14,6 +14,7 @@ CONFIG_INITRAMFS_SOURCE="../tb10x-rootfs.cpio"
CONFIG_INITRAMFS_ROOT_UID=2100
CONFIG_INITRAMFS_ROOT_GID=501
# CONFIG_RD_GZIP is not set
+CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y
CONFIG_SYSCTL_SYSCALL=y
CONFIG_KALLSYMS_ALL=y
# CONFIG_AIO is not set
diff --git a/arch/arc/configs/vdk_hs38_defconfig b/arch/arc/configs/vdk_hs38_defconfig
index 0c3b21416819..d7c858df520c 100644
--- a/arch/arc/configs/vdk_hs38_defconfig
+++ b/arch/arc/configs/vdk_hs38_defconfig
@@ -4,6 +4,7 @@ CONFIG_HIGH_RES_TIMERS=y
CONFIG_IKCONFIG=y
CONFIG_IKCONFIG_PROC=y
CONFIG_BLK_DEV_INITRD=y
+CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y
CONFIG_EMBEDDED=y
CONFIG_PERF_EVENTS=y
# CONFIG_VM_EVENT_COUNTERS is not set
diff --git a/arch/arc/configs/vdk_hs38_smp_defconfig b/arch/arc/configs/vdk_hs38_smp_defconfig
index f9ad9d3ee702..015c1d43889e 100644
--- a/arch/arc/configs/vdk_hs38_smp_defconfig
+++ b/arch/arc/configs/vdk_hs38_smp_defconfig
@@ -4,6 +4,7 @@ CONFIG_HIGH_RES_TIMERS=y
CONFIG_IKCONFIG=y
CONFIG_IKCONFIG_PROC=y
CONFIG_BLK_DEV_INITRD=y
+CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y
CONFIG_EMBEDDED=y
CONFIG_PERF_EVENTS=y
# CONFIG_VM_EVENT_COUNTERS is not set
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
--
2.17.1