[PATCH] Fixes for compiling with clang

[PATCH] Fixes for compiling with clang

[Peter Foley]

Move definition of HOSTCC to allow use of cc-name.
Suppress warnings about unsupported optimization options.
Disable clang's integrated assembler which is incompatible with kernel
asm constructs.

Signed-off-by: Peter Foley <pefoley2@pefoley.com>
---
 Makefile | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/Makefile b/Makefile
index 0ede48ba5aaf..b69ad7e4a6d2 100644
--- a/Makefile
+++ b/Makefile
@@ -299,16 +299,6 @@ CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \
 	  else if [ -x /bin/bash ]; then echo /bin/bash; \
 	  else echo sh; fi ; fi)
 
-HOSTCC       = gcc
-HOSTCXX      = g++
-HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89
-HOSTCXXFLAGS = -O2
-
-ifeq ($(shell $(HOSTCC) -v 2>&1 | grep -c "clang version"), 1)
-HOSTCFLAGS  += -Wno-unused-value -Wno-unused-parameter \
-		-Wno-missing-field-initializers -fno-delete-null-pointer-checks
-endif
-
 # Decide whether to build built-in, modular, or both.
 # Normally, just do built-in.
 
@@ -343,6 +333,16 @@ export KBUILD_CHECKSRC KBUILD_SRC KBUILD_EXTMOD
 scripts/Kbuild.include: ;
 include scripts/Kbuild.include
 
+HOSTCC       = gcc
+HOSTCXX      = g++
+HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89 \
+               -Wno-unused-value -Wno-unused-parameter -Wno-missing-field-initializers
+HOSTCXXFLAGS = -O2
+
+ifneq ($(cc-name),clang)
+HOSTCFLAGS +=  -fno-delete-null-pointer-checks
+endif
+
 # Make variables (CC, etc...)
 AS		= $(CROSS_COMPILE)as
 LD		= $(CROSS_COMPILE)ld
@@ -685,6 +685,7 @@ KBUILD_CFLAGS += $(stackp-flag)
 ifeq ($(cc-name),clang)
 KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
 KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
+KBUILD_CFLAGS += $(call cc-disable-warning, ignored-optimization-argument)
 KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
 KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)
 KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
@@ -695,6 +696,8 @@ KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)
 # See modpost pattern 2
 KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)
 KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)
+KBUILD_CFLAGS += $(call cc-option, -fno-integrated-as)
+KBUILD_AFLAGS += $(call cc-option, -fno-integrated-as)
 else
 
 # These warnings generated too much noise in a regular build.
-- 
2.11.0.rc2

Re: [PATCH] Fixes for compiling with clang

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1529 bytes --]

Hi Peter,

[auto build test ERROR on kbuild/for-next]
[also build test ERROR on v4.9-rc6 next-20161125]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Peter-Foley/Fixes-for-compiling-with-clang/20161126-124017
base:   https://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild.git for-next
config: avr32-atngw100_defconfig (attached as .config)
compiler: avr-gcc (GCC) 4.9.2
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=avr32 

All errors (new ones prefixed by >>):

>> /bin/sh: 0: Illegal option - 
--
>> /bin/sh: 0: Illegal option - 
   kernel/time/Kconfig:155:warning: range is invalid
--
>> /bin/sh: 0: Illegal option - 
   kernel/time/Kconfig:155:warning: range is invalid
>> /bin/sh: 0: Illegal option - 
   avr-gcc: error: unrecognized command line option '-mno-pic'
   avr-gcc: error: unrecognized command line option '-march=ap'
   make[2]: *** [kernel/bounds.s] Error 1
   make[2]: Target '__build' not remade because of errors.
   make[1]: *** [prepare0] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [sub-make] Error 2

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 12514 bytes --]

Re: [PATCH] Fixes for compiling with clang

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1546 bytes --]

Hi Peter,

[auto build test ERROR on kbuild/for-next]
[also build test ERROR on v4.9-rc6 next-20161125]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Peter-Foley/Fixes-for-compiling-with-clang/20161126-124017
base:   https://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild.git for-next
config: alpha-allyesconfig (attached as .config)
compiler: alpha-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=alpha 

All errors (new ones prefixed by >>):

>> /bin/bash: - : invalid option
   Usage:	/bin/bash [GNU long option] [option] ...
   	/bin/bash [GNU long option] [option] script-file ...
   GNU long options:
   	--debug
   	--debugger
   	--dump-po-strings
   	--dump-strings
   	--help
   	--init-file
   	--login
   	--noediting
   	--noprofile
   	--norc
   	--posix
   	--rcfile
   	--restricted
   	--verbose
   	--version
   Shell options:
   	-ilrsD or -c command or -O shopt_option		(invocation only)
   	-abefhkmnptuvxBCHP or -o option
   make[1]: *** [vmlinux] Error 1
   make[1]: Target '_all' not remade because of errors.

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 46888 bytes --]

[PATCH v2] Fixes for compiling with clang

[Peter Foley]

Move definition of HOSTCC to allow use of cc-name.
Suppress warnings about unsupported optimization options.
Disable clang's integrated assembler which is incompatible with kernel
asm constructs.

Changes from v1:
* Move the $(cc-name) conditional below the definition of $(CC)

Signed-off-by: Peter Foley <pefoley2@pefoley.com>
---
 Makefile | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/Makefile b/Makefile
index 0ede48ba5aaf..b69ad7e4a6d2 100644
--- a/Makefile
+++ b/Makefile
@@ -299,16 +299,6 @@ CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \
 	  else if [ -x /bin/bash ]; then echo /bin/bash; \
 	  else echo sh; fi ; fi)
 
-HOSTCC       = gcc
-HOSTCXX      = g++
-HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89
-HOSTCXXFLAGS = -O2
-
-ifeq ($(shell $(HOSTCC) -v 2>&1 | grep -c "clang version"), 1)
-HOSTCFLAGS  += -Wno-unused-value -Wno-unused-parameter \
-		-Wno-missing-field-initializers -fno-delete-null-pointer-checks
-endif
-
 # Decide whether to build built-in, modular, or both.
 # Normally, just do built-in.
 
@@ -343,6 +333,16 @@ export KBUILD_CHECKSRC KBUILD_SRC KBUILD_EXTMOD
 scripts/Kbuild.include: ;
 include scripts/Kbuild.include
 
+HOSTCC       = gcc
+HOSTCXX      = g++
+HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89 \
+               -Wno-unused-value -Wno-unused-parameter -Wno-missing-field-initializers
+HOSTCXXFLAGS = -O2
+
+ifneq ($(cc-name),clang)
+HOSTCFLAGS +=  -fno-delete-null-pointer-checks
+endif
+
 # Make variables (CC, etc...)
 AS		= $(CROSS_COMPILE)as
 LD		= $(CROSS_COMPILE)ld
@@ -685,6 +685,7 @@ KBUILD_CFLAGS += $(stackp-flag)
 ifeq ($(cc-name),clang)
 KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
 KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
+KBUILD_CFLAGS += $(call cc-disable-warning, ignored-optimization-argument)
 KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
 KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)
 KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
@@ -695,6 +696,8 @@ KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)
 # See modpost pattern 2
 KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)
 KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)
+KBUILD_CFLAGS += $(call cc-option, -fno-integrated-as)
+KBUILD_AFLAGS += $(call cc-option, -fno-integrated-as)
 else
 
 # These warnings generated too much noise in a regular build.
-- 
2.11.0.rc2

[PATCH v3] Fixes for compiling with clang

[Peter Foley]

Move definition of HOSTCC to allow use of cc-name.
Suppress warnings about unsupported optimization options.
Disable clang's integrated assembler which is incompatible with kernel
asm constructs.

Changes from v1:
* Move the $(cc-name) conditional below the definition of $(CC)
Changes from v2:
* Actually commit the changes in v2.

Signed-off-by: Peter Foley <pefoley2@pefoley.com>
---
 Makefile | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/Makefile b/Makefile
index 0ede48ba5aaf..94402cef6622 100644
--- a/Makefile
+++ b/Makefile
@@ -299,16 +299,6 @@ CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \
 	  else if [ -x /bin/bash ]; then echo /bin/bash; \
 	  else echo sh; fi ; fi)
 
-HOSTCC       = gcc
-HOSTCXX      = g++
-HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89
-HOSTCXXFLAGS = -O2
-
-ifeq ($(shell $(HOSTCC) -v 2>&1 | grep -c "clang version"), 1)
-HOSTCFLAGS  += -Wno-unused-value -Wno-unused-parameter \
-		-Wno-missing-field-initializers -fno-delete-null-pointer-checks
-endif
-
 # Decide whether to build built-in, modular, or both.
 # Normally, just do built-in.
 
@@ -373,6 +363,15 @@ LDFLAGS_vmlinux =
 CFLAGS_GCOV	= -fprofile-arcs -ftest-coverage -fno-tree-loop-im -Wno-maybe-uninitialized
 CFLAGS_KCOV	:= $(call cc-option,-fsanitize-coverage=trace-pc,)
 
+HOSTCC       = gcc
+HOSTCXX      = g++
+HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89 \
+               -Wno-unused-value -Wno-unused-parameter -Wno-missing-field-initializers
+HOSTCXXFLAGS = -O2
+
+ifneq ($(cc-name),clang)
+HOSTCFLAGS +=  -fno-delete-null-pointer-checks
+endif
 
 # Use USERINCLUDE when you must reference the UAPI directories only.
 USERINCLUDE    := \
@@ -685,6 +684,7 @@ KBUILD_CFLAGS += $(stackp-flag)
 ifeq ($(cc-name),clang)
 KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
 KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
+KBUILD_CFLAGS += $(call cc-disable-warning, ignored-optimization-argument)
 KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
 KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)
 KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
@@ -695,6 +695,8 @@ KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)
 # See modpost pattern 2
 KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)
 KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)
+KBUILD_CFLAGS += $(call cc-option, -fno-integrated-as)
+KBUILD_AFLAGS += $(call cc-option, -fno-integrated-as)
 else
 
 # These warnings generated too much noise in a regular build.
-- 
2.11.0.rc2

[PATCH v4] Fixes for compiling with clang

[Peter Foley]

Fix reversed conditional checking if HOSTCC is clang.
Suppress warnings about unsupported optimization options.
Suppress warnings about unused functions, as they are generated for
every module and are therefore far too spammy.
Disable clang's integrated assembler which is incompatible with kernel
asm constructs.

Changes from v1:
* Move the $(cc-name) conditional below the definition of $(CC)
Changes from v2:
* Actually commit the changes in v2.
Changes from v3:
* HOSTCC is not guaranteed to be the same as CC, adjust accordingly.

Signed-off-by: Peter Foley <pefoley2@pefoley.com>
---
 Makefile | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index 694111b43cf8..9c4803a74117 100644
--- a/Makefile
+++ b/Makefile
@@ -301,12 +301,12 @@ CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \
 
 HOSTCC       = gcc
 HOSTCXX      = g++
-HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89
+HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89 \
+               -Wno-unused-value -Wno-unused-parameter -Wno-missing-field-initializers
 HOSTCXXFLAGS = -O2
 
-ifeq ($(shell $(HOSTCC) -v 2>&1 | grep -c "clang version"), 1)
-HOSTCFLAGS  += -Wno-unused-value -Wno-unused-parameter \
-		-Wno-missing-field-initializers -fno-delete-null-pointer-checks
+ifneq ($(shell $(HOSTCC) -v 2>&1 | grep -c "clang version"), 1)
+HOSTCFLAGS +=  -fno-delete-null-pointer-checks
 endif
 
 # Decide whether to build built-in, modular, or both.
@@ -685,7 +685,9 @@ KBUILD_CFLAGS += $(stackp-flag)
 ifeq ($(cc-name),clang)
 KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
 KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
+KBUILD_CFLAGS += $(call cc-disable-warning, ignored-optimization-argument)
 KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-function)
 KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)
 KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
 # Quiet clang warning: comparison of unsigned expression < 0 is always false
@@ -695,6 +697,8 @@ KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)
 # See modpost pattern 2
 KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)
 KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)
+KBUILD_CFLAGS += $(call cc-option, -fno-integrated-as)
+KBUILD_AFLAGS += $(call cc-option, -fno-integrated-as)
 else
 
 # These warnings generated too much noise in a regular build.
-- 
2.11.0.rc2

Re: [PATCH v4] Fixes for compiling with clang

[Michal Marek]

Dne 28.11.2016 v 07:44 Peter Foley napsal(a):
> Fix reversed conditional checking if HOSTCC is clang.
> Suppress warnings about unsupported optimization options.
> Suppress warnings about unused functions, as they are generated for
> every module and are therefore far too spammy.
> Disable clang's integrated assembler which is incompatible with kernel
> asm constructs.
> 
> Changes from v1:
> * Move the $(cc-name) conditional below the definition of $(CC)
> Changes from v2:
> * Actually commit the changes in v2.
> Changes from v3:
> * HOSTCC is not guaranteed to be the same as CC, adjust accordingly.
> 
> Signed-off-by: Peter Foley <pefoley2@pefoley.com>
> ---
>  Makefile | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 694111b43cf8..9c4803a74117 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -301,12 +301,12 @@ CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \
>  
>  HOSTCC       = gcc
>  HOSTCXX      = g++
> -HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89
> +HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89 \
> +               -Wno-unused-value -Wno-unused-parameter -Wno-missing-field-initializers
>  HOSTCXXFLAGS = -O2

This adds new -Wno-* options also for the gcc case, is there a reason
for this? Also, the -Wno-missing-field-initializers option is not
available in some old gccs, so we would need a HOSTCC equivalent of
cc-disable-warning.

Michal

Re: [PATCH v4] Fixes for compiling with clang

[Peter Foley]

On Tue, Nov 29, 2016 at 6:22 AM, Michal Marek <mmarek@suse.com> wrote:
> Dne 28.11.2016 v 07:44 Peter Foley napsal(a):
> This adds new -Wno-* options also for the gcc case, is there a reason
> for this? Also, the -Wno-missing-field-initializers option is not
> available in some old gccs, so we would need a HOSTCC equivalent of
> cc-disable-warning.
>
> Michal

It appeared that the conditional was simply reversed, as
-fno-delete-null-pointer-checks is only supported by gcc, and
explicitly not supported by clang.
(see https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/Makefile?id=61163efae02040f66a95c8ed17f4407951ba58fa)
It could be that the fno-delete-null-pointer-checks option was simply
misplaced, and the Wno-options should still be guarded by if(clang),
would that be a better approach?

Thanks,

Peter

Re: [PATCH v4] Fixes for compiling with clang

[Michal Marek]

On 2016-12-01 19:13, Peter Foley wrote:
> On Tue, Nov 29, 2016 at 6:22 AM, Michal Marek <mmarek@suse.com> wrote:
>> Dne 28.11.2016 v 07:44 Peter Foley napsal(a):
>> This adds new -Wno-* options also for the gcc case, is there a reason
>> for this? Also, the -Wno-missing-field-initializers option is not
>> available in some old gccs, so we would need a HOSTCC equivalent of
>> cc-disable-warning.
>>
>> Michal
> 
> It appeared that the conditional was simply reversed, as
> -fno-delete-null-pointer-checks is only supported by gcc, and
> explicitly not supported by clang.
> (see https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/Makefile?id=61163efae02040f66a95c8ed17f4407951ba58fa)
> It could be that the fno-delete-null-pointer-checks option was simply
> misplaced, and the Wno-options should still be guarded by if(clang),
> would that be a better approach?

I think so. The -Wno-* options had not been present before clang support
was added. It really looks like the -fno-delete-null-pointer-checks
should not be there. Added Behan to CC.

Michal