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  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

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  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

Re: [PATCH v4] Fixes for compiling with clang

[Peter Foley]

On Tue, Nov 29, 2016 at 6:22 AM, Michal Marek  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

[Peter Foley]

On Tue, Nov 29, 2016 at 6:22 AM, Michal Marek  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]

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 
> ---
>  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

[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 
> ---
>  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