[PATCH v2 1/2] kbuild: replace cc-name test with CONFIG_CC_IS_CLANG

From: Masahiro Yamada
Date: Tue Oct 30 2018 - 09:30:16 EST


Evaluating cc-name invokes the compiler every time even when you are
not compiling anything, like 'make help'. This is not efficient.

The compiler type has been already detected in the Kconfig stage.
Use CONFIG_CC_IS_CLANG, instead.

Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
Acked-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> (powerpc)
---

Changes in v2:
- Use ifdef/ifndef insteaed of ifeq/ifneq

Makefile | 2 +-
arch/mips/Makefile | 2 +-
arch/mips/vdso/Makefile | 2 +-
arch/powerpc/Makefile | 4 ++--
scripts/Makefile.extrawarn | 2 +-
5 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index 0a42d06..1c0696d 100644
--- a/Makefile
+++ b/Makefile
@@ -707,7 +707,7 @@ stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG) := -fstack-protector-strong

KBUILD_CFLAGS += $(stackp-flags-y)

-ifeq ($(cc-name),clang)
+ifdef CONFIG_CC_IS_CLANG
KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)
KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
diff --git a/arch/mips/Makefile b/arch/mips/Makefile
index 15a84cf..6841049 100644
--- a/arch/mips/Makefile
+++ b/arch/mips/Makefile
@@ -128,7 +128,7 @@ cflags-y += -ffreestanding
# clang's output will be based upon the build machine. So for clang we simply
# unconditionally specify -EB or -EL as appropriate.
#
-ifeq ($(cc-name),clang)
+ifdef CONFIG_CC_IS_CLANG
cflags-$(CONFIG_CPU_BIG_ENDIAN) += -EB
cflags-$(CONFIG_CPU_LITTLE_ENDIAN) += -EL
else
diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile
index 34605ca..58a0315 100644
--- a/arch/mips/vdso/Makefile
+++ b/arch/mips/vdso/Makefile
@@ -10,7 +10,7 @@ ccflags-vdso := \
$(filter -march=%,$(KBUILD_CFLAGS)) \
-D__VDSO__

-ifeq ($(cc-name),clang)
+ifdef CONFIG_CC_IS_CLANG
ccflags-vdso += $(filter --target=%,$(KBUILD_CFLAGS))
endif

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 17be664..8a2ce14 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -96,7 +96,7 @@ aflags-$(CONFIG_CPU_BIG_ENDIAN) += $(call cc-option,-mabi=elfv1)
aflags-$(CONFIG_CPU_LITTLE_ENDIAN) += -mabi=elfv2
endif

-ifneq ($(cc-name),clang)
+ifndef CONFIG_CC_IS_CLANG
cflags-$(CONFIG_CPU_LITTLE_ENDIAN) += -mno-strict-align
endif

@@ -175,7 +175,7 @@ endif
# Work around gcc code-gen bugs with -pg / -fno-omit-frame-pointer in gcc <= 4.8
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=44199
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52828
-ifneq ($(cc-name),clang)
+ifndef CONFIG_CC_IS_CLANG
CC_FLAGS_FTRACE += $(call cc-ifversion, -lt, 0409, -mno-sched-epilog)
endif
endif
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 24b2fb1..800a10f 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -64,7 +64,7 @@ endif
KBUILD_CFLAGS += $(warning)
else

-ifeq ($(cc-name),clang)
+ifdef CONFIG_CC_IS_CLANG
KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides)
KBUILD_CFLAGS += $(call cc-disable-warning, unused-value)
KBUILD_CFLAGS += $(call cc-disable-warning, format)
--
2.7.4