* [PATCH 1/3] init/Kconfig: rework help of CONFIG_CC_OPTIMIZE_FOR_SIZE
@ 2019-08-20 17:09 Masahiro Yamada
2019-08-20 17:09 ` [PATCH 2/3] kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC Masahiro Yamada
2019-08-20 17:09 ` [PATCH 3/3] kbuild: remove ARCH_{CPP,A,C}FLAGS Masahiro Yamada
0 siblings, 2 replies; 7+ messages in thread
From: Masahiro Yamada @ 2019-08-20 17:09 UTC (permalink / raw)
To: linux-kbuild
Cc: Vineet Gupta, linux-snps-arc, Arnd Bergmann, Masahiro Yamada,
linux-kernel
CONFIG_CC_OPTIMIZE_FOR_SIZE was originally an independent boolean
option, but commit 877417e6ffb9 ("Kbuild: change CC_OPTIMIZE_FOR_SIZE
definition") turned it into a choice between _PERFORMANCE and _SIZE.
The phrase "If unsure, say N." sounds like an independent option.
Reword the help text to make it appropriate for the choice menu.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---
init/Kconfig | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/init/Kconfig b/init/Kconfig
index bf971b5c707d..149efd82447f 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1219,10 +1219,8 @@ config CC_OPTIMIZE_FOR_SIZE
bool "Optimize for size"
imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives
help
- Enabling this option will pass "-Os" instead of "-O2" to
- your compiler resulting in a smaller kernel.
-
- If unsure, say N.
+ Choosing this option will pass "-Os" to your compiler resulting
+ in a smaller kernel.
endchoice
--
2.17.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH 2/3] kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC
2019-08-20 17:09 [PATCH 1/3] init/Kconfig: rework help of CONFIG_CC_OPTIMIZE_FOR_SIZE Masahiro Yamada
@ 2019-08-20 17:09 ` Masahiro Yamada
2019-08-28 16:36 ` Masahiro Yamada
2019-08-30 16:43 ` [PATCH 2/3] kbuild, arc: " Vineet Gupta
2019-08-20 17:09 ` [PATCH 3/3] kbuild: remove ARCH_{CPP,A,C}FLAGS Masahiro Yamada
1 sibling, 2 replies; 7+ messages in thread
From: Masahiro Yamada @ 2019-08-20 17:09 UTC (permalink / raw)
To: linux-kbuild
Cc: Vineet Gupta, linux-snps-arc, Arnd Bergmann, Masahiro Yamada,
Michal Marek, linux-kernel
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
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH 3/3] kbuild: remove ARCH_{CPP,A,C}FLAGS
2019-08-20 17:09 [PATCH 1/3] init/Kconfig: rework help of CONFIG_CC_OPTIMIZE_FOR_SIZE Masahiro Yamada
2019-08-20 17:09 ` [PATCH 2/3] kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC Masahiro Yamada
@ 2019-08-20 17:09 ` Masahiro Yamada
1 sibling, 0 replies; 7+ messages in thread
From: Masahiro Yamada @ 2019-08-20 17:09 UTC (permalink / raw)
To: linux-kbuild
Cc: Vineet Gupta, linux-snps-arc, Arnd Bergmann, Masahiro Yamada,
Jonathan Corbet, Michal Marek, linux-doc, linux-kernel
These flags were added by commit 61754c18752f ("kbuild: Allow arch
Makefiles to override {cpp,ld,c}flags") to allow ARC to override -O2.
We did not see any other usage after all. Now that ARC switched to
CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3, there is no more user of
these variables.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---
Documentation/kbuild/makefiles.rst | 7 -------
Makefile | 14 ++++----------
2 files changed, 4 insertions(+), 17 deletions(-)
diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst
index 36ba92e199d2..712cdbcdbe91 100644
--- a/Documentation/kbuild/makefiles.rst
+++ b/Documentation/kbuild/makefiles.rst
@@ -988,13 +988,6 @@ When kbuild executes, the following steps are followed (roughly):
$(KBUILD_ARFLAGS) set by the top level Makefile to "D" (deterministic
mode) if this option is supported by $(AR).
- ARCH_CPPFLAGS, ARCH_AFLAGS, ARCH_CFLAGS Overrides the kbuild defaults
-
- These variables are appended to the KBUILD_CPPFLAGS,
- KBUILD_AFLAGS, and KBUILD_CFLAGS, respectively, after the
- top-level Makefile has set any other flags. This provides a
- means for an architecture to override the defaults.
-
KBUILD_LDS
The linker script with full path. Assigned by the top-level Makefile.
diff --git a/Makefile b/Makefile
index 891e47da503f..6551f136afb0 100644
--- a/Makefile
+++ b/Makefile
@@ -661,11 +661,6 @@ RETPOLINE_VDSO_CFLAGS := $(call cc-option,$(RETPOLINE_VDSO_CFLAGS_GCC),$(call cc
export RETPOLINE_CFLAGS
export RETPOLINE_VDSO_CFLAGS
-# The arch Makefile can set ARCH_{CPP,A,C}FLAGS to override the default
-# values of the respective KBUILD_* variables
-ARCH_CPPFLAGS :=
-ARCH_AFLAGS :=
-ARCH_CFLAGS :=
include arch/$(SRCARCH)/Makefile
ifdef need-config
@@ -918,11 +913,10 @@ include scripts/Makefile.kasan
include scripts/Makefile.extrawarn
include scripts/Makefile.ubsan
-# Add any arch overrides and user supplied CPPFLAGS, AFLAGS and CFLAGS as the
-# last assignments
-KBUILD_CPPFLAGS += $(ARCH_CPPFLAGS) $(KCPPFLAGS)
-KBUILD_AFLAGS += $(ARCH_AFLAGS) $(KAFLAGS)
-KBUILD_CFLAGS += $(ARCH_CFLAGS) $(KCFLAGS)
+# Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
+KBUILD_CPPFLAGS += $(KCPPFLAGS)
+KBUILD_AFLAGS += $(KAFLAGS)
+KBUILD_CFLAGS += $(KCFLAGS)
KBUILD_LDFLAGS_MODULE += --build-id
LDFLAGS_vmlinux += --build-id
--
2.17.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH 2/3] kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC
2019-08-20 17:09 ` [PATCH 2/3] kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC Masahiro Yamada
@ 2019-08-28 16:36 ` Masahiro Yamada
2019-08-30 16:43 ` [PATCH 2/3] kbuild, arc: " Vineet Gupta
1 sibling, 0 replies; 7+ messages in thread
From: Masahiro Yamada @ 2019-08-28 16:36 UTC (permalink / raw)
To: Linux Kbuild mailing list
Cc: Vineet Gupta, arcml, Arnd Bergmann, Michal Marek,
Linux Kernel Mailing List
Hi Vineet,
On Wed, Aug 21, 2019 at 2:10 AM Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
>
> 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>
> ---
If it is OK to apply this to my kbuild tree,
can I get your ACK?
If you see any problem, please let me know.
Thanks.
>
> 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
>
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 2/3] kbuild, arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC
2019-08-20 17:09 ` [PATCH 2/3] kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC Masahiro Yamada
2019-08-28 16:36 ` Masahiro Yamada
@ 2019-08-30 16:43 ` Vineet Gupta
2019-09-03 15:08 ` Masahiro Yamada
1 sibling, 1 reply; 7+ messages in thread
From: Vineet Gupta @ 2019-08-30 16:43 UTC (permalink / raw)
To: Masahiro Yamada, linux-kbuild
Cc: Michal Marek, Arnd Bergmann, linux-kernel, linux-snps-arc
On 8/20/19 10:09 AM, Masahiro Yamada wrote:
> 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.
Why, it seems like a good generic facility for arches to over-ride stuff
(specially adding any toggles at the end of cmdline).
And even if there are no current users, it would be good to have. I understand we
don't keep code for future, but strictly this is meta-code ;-)
> 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.
But this is a separate issue and was done on purpose because of unbearable build
spew at the time. As an experiment I enabled it in current kernel and at -O3 we
still get the dreaded spew in net/sunrpc/xdr.c and some more in net/ipv4. The spew
doesn't happen at -O2 and seems not ARC specific as I can see this with ARM -O3
build with gcc 7.3 (buildroot 2018.08)
| $ make ARCH=arm CROSS_COMPILE=arm-linux- net
| ......
| ......
| ../net/sunrpc/xdr.c: In function ‘xdr_encode_word’:
| ../net/sunrpc/xdr.c:1199:2: warning: ‘subbuf.tail[0].iov_base’ may be used
| uninitialized in this function [-Wmaybe-uninitialized]
| memcpy(subbuf->tail[0].iov_base, obj, this_len);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| ../net/sunrpc/xdr.c:1205:17: note: ‘subbuf.tail[0].iov_base’ was declared here
| struct xdr_buf subbuf;
I understand the value of this toggle, but the spew is too much and at times
obfuscated likely other real issues.
> 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.
My first reaction to adding this to all defconfigs was that this was inelegant :
for lack of better word :-)
But indeed it seems better this way as we can now experiment with -O2 vs. -O3 from
config, rather than hardwiring to -O3.
So if you could please split out the Wmaybe-uninitialized change
Acked-by: Vineet Gupta <vgupta@synopsys.com>
> 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
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 2/3] kbuild, arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC
2019-08-30 16:43 ` [PATCH 2/3] kbuild, arc: " Vineet Gupta
@ 2019-09-03 15:08 ` Masahiro Yamada
2019-09-04 3:08 ` Vineet Gupta
0 siblings, 1 reply; 7+ messages in thread
From: Masahiro Yamada @ 2019-09-03 15:08 UTC (permalink / raw)
To: Vineet Gupta
Cc: Linux Kbuild mailing list, Michal Marek, Arnd Bergmann,
Linux Kernel Mailing List, arcml
On Sat, Aug 31, 2019 at 1:43 AM Vineet Gupta <vineetg76@gmail.com> wrote:
>
> On 8/20/19 10:09 AM, Masahiro Yamada wrote:
> > 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.
>
> Why, it seems like a good generic facility for arches to over-ride stuff
> (specially adding any toggles at the end of cmdline).
>
> And even if there are no current users, it would be good to have. I understand we
> don't keep code for future, but strictly this is meta-code ;-)
We can re-add it whenever we need it.
> > 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.
>
> But this is a separate issue and was done on purpose because of unbearable build
> spew at the time. As an experiment I enabled it in current kernel and at -O3 we
> still get the dreaded spew in net/sunrpc/xdr.c and some more in net/ipv4. The spew
> doesn't happen at -O2 and seems not ARC specific as I can see this with ARM -O3
> build with gcc 7.3 (buildroot 2018.08)
>
> | $ make ARCH=arm CROSS_COMPILE=arm-linux- net
> | ......
> | ......
> | ../net/sunrpc/xdr.c: In function ‘xdr_encode_word’:
> | ../net/sunrpc/xdr.c:1199:2: warning: ‘subbuf.tail[0].iov_base’ may be used
> | uninitialized in this function [-Wmaybe-uninitialized]
> | memcpy(subbuf->tail[0].iov_base, obj, this_len);
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> | ../net/sunrpc/xdr.c:1205:17: note: ‘subbuf.tail[0].iov_base’ was declared here
> | struct xdr_buf subbuf;
>
>
> I understand the value of this toggle, but the spew is too much and at times
> obfuscated likely other real issues.
> > 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.
>
> My first reaction to adding this to all defconfigs was that this was inelegant :
> for lack of better word :-)
>
> But indeed it seems better this way as we can now experiment with -O2 vs. -O3 from
> config, rather than hardwiring to -O3.
>
> So if you could please split out the Wmaybe-uninitialized change
I could not understand your request.
I added 'imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED'
for CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3.
I cannot split it out. Otherwise, you will see false-positive
maybe-uninitialized warnings.
> Acked-by: Vineet Gupta <vgupta@synopsys.com>
Thanks.
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 2/3] kbuild, arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC
2019-09-03 15:08 ` Masahiro Yamada
@ 2019-09-04 3:08 ` Vineet Gupta
0 siblings, 0 replies; 7+ messages in thread
From: Vineet Gupta @ 2019-09-04 3:08 UTC (permalink / raw)
To: Masahiro Yamada
Cc: Linux Kbuild mailing list, Michal Marek, Arnd Bergmann,
Linux Kernel Mailing List, arcml
On 9/3/19 8:08 AM, Masahiro Yamada wrote:
>> So if you could please split out the Wmaybe-uninitialized change
> I could not understand your request.
>
> I added 'imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED'
> for CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3.
>
> I cannot split it out. Otherwise, you will see false-positive
> maybe-uninitialized warnings.
Sorry I must have overlooked this part. So no issues now !
Thx,
-Vineet
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2019-09-04 3:08 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-08-20 17:09 [PATCH 1/3] init/Kconfig: rework help of CONFIG_CC_OPTIMIZE_FOR_SIZE Masahiro Yamada
2019-08-20 17:09 ` [PATCH 2/3] kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC Masahiro Yamada
2019-08-28 16:36 ` Masahiro Yamada
2019-08-30 16:43 ` [PATCH 2/3] kbuild, arc: " Vineet Gupta
2019-09-03 15:08 ` Masahiro Yamada
2019-09-04 3:08 ` Vineet Gupta
2019-08-20 17:09 ` [PATCH 3/3] kbuild: remove ARCH_{CPP,A,C}FLAGS Masahiro Yamada
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