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

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 <redacted>
---

 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..bd93bc3 100644
--- a/Makefile
+++ b/Makefile

@@ -707,7 +707,7 @@ stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG)      := -fstack-protector-strong
 
 KBUILD_CFLAGS += $(stackp-flags-y)
 
-ifeq ($(cc-name),clang)
+ifeq ($(CONFIG_CC_IS_CLANG),y)
 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..ad1c418 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 ($(cc-name),clang)
+ifeq ($(CONFIG_CC_IS_CLANG),y)
 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..e2b055e 100644
--- a/arch/mips/vdso/Makefile
+++ b/arch/mips/vdso/Makefile

@@ -10,7 +10,7 @@ ccflags-vdso := \
 	$(filter -march=%,$(KBUILD_CFLAGS)) \
 	-D__VDSO__
 
-ifeq ($(cc-name),clang)
+ifeq ($(CONFIG_CC_IS_CLANG),y)
 ccflags-vdso += $(filter --target=%,$(KBUILD_CFLAGS))
 endif
 

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 17be664..338e827 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 ($(cc-name),clang)
+ifneq ($(CONFIG_CC_IS_CLANG),y)
   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 ($(cc-name),clang)
+ifneq ($(CONFIG_CC_IS_CLANG),y)
 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..88129e5 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn

@@ -64,7 +64,7 @@ endif
 KBUILD_CFLAGS += $(warning)
 else
 
-ifeq ($(cc-name),clang)
+ifeq ($(CONFIG_CC_IS_CLANG),y)
 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

Masahiro Yamada [off-list ref] writes:

Does this behave like other CONFIG variables, ie. it will not be defined
when it's false?

And if so can't we use ifdef/ifndef? eg:

ifndef CONFIG_CC_IS_CLANG
  CC_FLAGS_FTRACE	+= $(call cc-ifversion, -lt, 0409, -mno-sched-epilog)

That reads cleaner to me.

Still this patch is fine as is:

Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

cheers

On Tue, Oct 30, 2018 at 9:36 PM Michael Ellerman [off-list ref] wrote:

Masahiro Yamada [off-list ref] writes:

quoted

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 17be664..338e827 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 ($(cc-name),clang)
+ifneq ($(CONFIG_CC_IS_CLANG),y)
   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 ($(cc-name),clang)
+ifneq ($(CONFIG_CC_IS_CLANG),y)
 CC_FLAGS_FTRACE      += $(call cc-ifversion, -lt, 0409, -mno-sched-epilog)
 endif
 endif

Does this behave like other CONFIG variables, ie. it will not be defined
when it's false?

Right.

And if so can't we use ifdef/ifndef? eg:

ifndef CONFIG_CC_IS_CLANG
  CC_FLAGS_FTRACE       += $(call cc-ifversion, -lt, 0409, -mno-sched-epilog)

That reads cleaner to me.

OK, will do respin if you prefer ifdef/ifndef style.

Still this patch is fine as is:

Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

cheers

-- 
Best Regards
Masahiro Yamada

Masahiro Yamada [off-list ref] writes:

On Tue, Oct 30, 2018 at 9:36 PM Michael Ellerman [off-list ref] wrote:

quoted

Masahiro Yamada [off-list ref] writes:

quoted

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 17be664..338e827 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 ($(cc-name),clang)
+ifneq ($(CONFIG_CC_IS_CLANG),y)
   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 ($(cc-name),clang)
+ifneq ($(CONFIG_CC_IS_CLANG),y)
 CC_FLAGS_FTRACE      += $(call cc-ifversion, -lt, 0409, -mno-sched-epilog)
 endif
 endif

Does this behave like other CONFIG variables, ie. it will not be defined
when it's false?

Right.

quoted

And if so can't we use ifdef/ifndef? eg:

ifndef CONFIG_CC_IS_CLANG
  CC_FLAGS_FTRACE       += $(call cc-ifversion, -lt, 0409, -mno-sched-epilog)

That reads cleaner to me.

OK, will do respin if you prefer ifdef/ifndef style.

I do prefer it, but I can also fix it up later if you're in a hurry to
get this merged.

cheers