diff mbox series

kbuild: consolidate Clang compiler flags

Message ID 1541386099-13118-1-git-send-email-yamada.masahiro@socionext.com
State Superseded
Headers show
Series kbuild: consolidate Clang compiler flags | expand

Commit Message

Masahiro Yamada Nov. 5, 2018, 2:48 a.m. UTC 
Add basic options for Clang such as --target, --prefix, --gcc-toolchain,
-no-integrated-as to a single variable CLANG_FLAGS.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

---

 Makefile | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

-- 
2.7.4

Comments

Stefan Agner Nov. 5, 2018, 9:09 a.m. UTC | #1 
On 05.11.2018 03:48, Masahiro Yamada wrote:
> Add basic options for Clang such as --target, --prefix, --gcc-toolchain,

> -no-integrated-as to a single variable CLANG_FLAGS.

> 

> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

> ---

> 

>  Makefile | 13 ++++++-------

>  1 file changed, 6 insertions(+), 7 deletions(-)

> 

> diff --git a/Makefile b/Makefile

> index 93315eb..58c838a 100644

> --- a/Makefile

> +++ b/Makefile

> @@ -487,18 +487,17 @@ endif

>  

>  ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)

>  ifneq ($(CROSS_COMPILE),)

> -CLANG_TARGET	:= --target=$(notdir $(CROSS_COMPILE:%-=%))

> +CLANG_FLAGS	= --target=$(notdir $(CROSS_COMPILE:%-=%))

>  GCC_TOOLCHAIN_DIR := $(dir $(shell which $(LD)))

> -CLANG_PREFIX	:= --prefix=$(GCC_TOOLCHAIN_DIR)

> +CLANG_FLAGS	+= --prefix=$(GCC_TOOLCHAIN_DIR)


So this will expand later now, is this ok?

--
Stefan

>  GCC_TOOLCHAIN	:= $(realpath $(GCC_TOOLCHAIN_DIR)/..)

>  endif

>  ifneq ($(GCC_TOOLCHAIN),)

> -CLANG_GCC_TC	:= --gcc-toolchain=$(GCC_TOOLCHAIN)

> +CLANG_FLAGS	+= --gcc-toolchain=$(GCC_TOOLCHAIN)

>  endif

> -KBUILD_CFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) $(CLANG_PREFIX)

> -KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) $(CLANG_PREFIX)

> -KBUILD_CFLAGS += $(call cc-option, -no-integrated-as)

> -KBUILD_AFLAGS += $(call cc-option, -no-integrated-as)

> +CLANG_FLAGS	+= $(call cc-option, -no-integrated-as)

> +KBUILD_CFLAGS	+= $(CLANG_FLAGS)

> +KBUILD_AFLAGS	+= $(CLANG_FLAGS)

>  endif

>  

>  RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern

> -mindirect-branch-register
Masahiro Yamada Nov. 5, 2018, 9:18 a.m. UTC | #2 
On Mon, Nov 5, 2018 at 6:10 PM Stefan Agner <stefan@agner.ch> wrote:
>

> On 05.11.2018 03:48, Masahiro Yamada wrote:

> > Add basic options for Clang such as --target, --prefix, --gcc-toolchain,

> > -no-integrated-as to a single variable CLANG_FLAGS.

> >

> > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

> > ---

> >

> >  Makefile | 13 ++++++-------

> >  1 file changed, 6 insertions(+), 7 deletions(-)

> >

> > diff --git a/Makefile b/Makefile

> > index 93315eb..58c838a 100644

> > --- a/Makefile

> > +++ b/Makefile

> > @@ -487,18 +487,17 @@ endif

> >

> >  ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)

> >  ifneq ($(CROSS_COMPILE),)

> > -CLANG_TARGET := --target=$(notdir $(CROSS_COMPILE:%-=%))

> > +CLANG_FLAGS  = --target=$(notdir $(CROSS_COMPILE:%-=%))

> >  GCC_TOOLCHAIN_DIR := $(dir $(shell which $(LD)))

> > -CLANG_PREFIX := --prefix=$(GCC_TOOLCHAIN_DIR)

> > +CLANG_FLAGS  += --prefix=$(GCC_TOOLCHAIN_DIR)

>

> So this will expand later now, is this ok?

>

> --

> Stefan

>

> >  GCC_TOOLCHAIN        := $(realpath $(GCC_TOOLCHAIN_DIR)/..)

> >  endif

> >  ifneq ($(GCC_TOOLCHAIN),)

> > -CLANG_GCC_TC := --gcc-toolchain=$(GCC_TOOLCHAIN)

> > +CLANG_FLAGS  += --gcc-toolchain=$(GCC_TOOLCHAIN)

> >  endif

> > -KBUILD_CFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) $(CLANG_PREFIX)

> > -KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) $(CLANG_PREFIX)

> > -KBUILD_CFLAGS += $(call cc-option, -no-integrated-as)

> > -KBUILD_AFLAGS += $(call cc-option, -no-integrated-as)

> > +CLANG_FLAGS  += $(call cc-option, -no-integrated-as)

> > +KBUILD_CFLAGS        += $(CLANG_FLAGS)

> > +KBUILD_AFLAGS        += $(CLANG_FLAGS)



CLANG_FLAGS is expanded here because KBUILD_CFLAGS and KBUILD_AFLAGS
are defined by using :=

So, it should be OK, but turning CLANG_FLAGS into a simple variable
will be a little more efficient since $(call cc-option, -no-integrated-as)
is evaluated just once.

(Or, this cc-option may not be necessary any longer.)

Will send v2.


Thanks.




> >  endif

> >

> >  RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern

> > -mindirect-branch-register




-- 
Best Regards
Masahiro Yamada
Nick Desaulniers Nov. 5, 2018, 5:59 p.m. UTC | #3 
On Mon, Nov 5, 2018 at 1:19 AM Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
>

> On Mon, Nov 5, 2018 at 6:10 PM Stefan Agner <stefan@agner.ch> wrote:

> >

> > On 05.11.2018 03:48, Masahiro Yamada wrote:

> > > Add basic options for Clang such as --target, --prefix, --gcc-toolchain,

> > > -no-integrated-as to a single variable CLANG_FLAGS.

> > >

> > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

> > > ---

> > >

> > >  Makefile | 13 ++++++-------

> > >  1 file changed, 6 insertions(+), 7 deletions(-)

> > >

> > > diff --git a/Makefile b/Makefile

> > > index 93315eb..58c838a 100644

> > > --- a/Makefile

> > > +++ b/Makefile

> > > @@ -487,18 +487,17 @@ endif

> > >

> > >  ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)

> > >  ifneq ($(CROSS_COMPILE),)

> > > -CLANG_TARGET := --target=$(notdir $(CROSS_COMPILE:%-=%))

> > > +CLANG_FLAGS  = --target=$(notdir $(CROSS_COMPILE:%-=%))

> > >  GCC_TOOLCHAIN_DIR := $(dir $(shell which $(LD)))

> > > -CLANG_PREFIX := --prefix=$(GCC_TOOLCHAIN_DIR)

> > > +CLANG_FLAGS  += --prefix=$(GCC_TOOLCHAIN_DIR)

> >

> > So this will expand later now, is this ok?

> >

> > --

> > Stefan

> >

> > >  GCC_TOOLCHAIN        := $(realpath $(GCC_TOOLCHAIN_DIR)/..)

> > >  endif

> > >  ifneq ($(GCC_TOOLCHAIN),)

> > > -CLANG_GCC_TC := --gcc-toolchain=$(GCC_TOOLCHAIN)

> > > +CLANG_FLAGS  += --gcc-toolchain=$(GCC_TOOLCHAIN)

> > >  endif

> > > -KBUILD_CFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) $(CLANG_PREFIX)

> > > -KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) $(CLANG_PREFIX)

> > > -KBUILD_CFLAGS += $(call cc-option, -no-integrated-as)

> > > -KBUILD_AFLAGS += $(call cc-option, -no-integrated-as)

> > > +CLANG_FLAGS  += $(call cc-option, -no-integrated-as)

> > > +KBUILD_CFLAGS        += $(CLANG_FLAGS)

> > > +KBUILD_AFLAGS        += $(CLANG_FLAGS)

>

>

> CLANG_FLAGS is expanded here because KBUILD_CFLAGS and KBUILD_AFLAGS

> are defined by using :=

>

> So, it should be OK, but turning CLANG_FLAGS into a simple variable

> will be a little more efficient since $(call cc-option, -no-integrated-as)

> is evaluated just once.

>

> (Or, this cc-option may not be necessary any longer.)

>

> Will send v2.


If the ultimate goal is not evaluate cc-option more than once,
removing cc-option from both KBUILD_CFLAGS and KBUILD_AFLAGS for clang
is the better approach; we always want those for clang
unconditionally. And if you by chance have an ancient version of clang
that doesn't support those flags, you wont be able to compile a kernel
anyways.  Eventually we want to get Clang's integrated assembler in
shape to be used to assemble the kernel, but I think we're a ways off
there still.


-- 
Thanks,
~Nick Desaulniers
diff mbox series

Patch

diff --git a/Makefile b/Makefile
index 93315eb..58c838a 100644
--- a/Makefile
+++ b/Makefile
@@ -487,18 +487,17 @@  endif
 
 ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)
 ifneq ($(CROSS_COMPILE),)
-CLANG_TARGET	:= --target=$(notdir $(CROSS_COMPILE:%-=%))
+CLANG_FLAGS	= --target=$(notdir $(CROSS_COMPILE:%-=%))
 GCC_TOOLCHAIN_DIR := $(dir $(shell which $(LD)))
-CLANG_PREFIX	:= --prefix=$(GCC_TOOLCHAIN_DIR)
+CLANG_FLAGS	+= --prefix=$(GCC_TOOLCHAIN_DIR)
 GCC_TOOLCHAIN	:= $(realpath $(GCC_TOOLCHAIN_DIR)/..)
 endif
 ifneq ($(GCC_TOOLCHAIN),)
-CLANG_GCC_TC	:= --gcc-toolchain=$(GCC_TOOLCHAIN)
+CLANG_FLAGS	+= --gcc-toolchain=$(GCC_TOOLCHAIN)
 endif
-KBUILD_CFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) $(CLANG_PREFIX)
-KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) $(CLANG_PREFIX)
-KBUILD_CFLAGS += $(call cc-option, -no-integrated-as)
-KBUILD_AFLAGS += $(call cc-option, -no-integrated-as)
+CLANG_FLAGS	+= $(call cc-option, -no-integrated-as)
+KBUILD_CFLAGS	+= $(CLANG_FLAGS)
+KBUILD_AFLAGS	+= $(CLANG_FLAGS)
 endif
 
 RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern -mindirect-branch-register