Re: [PATCH 3/5] lib/mpi: Fix for building for MIPS32 with Clang

From: Jussi Kivilinna <jussi.kivilinna@iki.fi>
To: Nathan Chancellor <natechancellor@gmail.com>,
	Ralf Baechle <ralf@linux-mips.org>,
	Paul Burton <paul.burton@mips.com>,
	James Hogan <jhogan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
	linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
	clang-built-linux@googlegroups.com,
	Vladimir Serbinenko <phcoder@gmail.com>
Subject: Re: [PATCH 3/5] lib/mpi: Fix for building for MIPS32 with Clang
Date: Mon, 12 Aug 2019 10:35:53 +0300
Message-ID: <ec4666a6-c7db-247b-de81-bb784bb9d649@iki.fi> (raw)
In-Reply-To: <20190812033120.43013-4-natechancellor@gmail.com>

Hello,

On 12.8.2019 6.31, Nathan Chancellor wrote:
> From: Vladimir Serbinenko <phcoder@gmail.com>
> 
> clang doesn't recognise =l / =h assembly operand specifiers but apparently
> handles C version well.
> 
> lib/mpi/generic_mpih-mul1.c:37:24: error: invalid use of a cast in a
> inline asm context requiring an l-value: remove the cast or build with
> -fheinous-gnu-extensions
>                 umul_ppmm(prod_high, prod_low, s1_ptr[j], s2_limb);
>                 ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> lib/mpi/longlong.h:652:20: note: expanded from macro 'umul_ppmm'
>         : "=l" ((USItype)(w0)), \
>                 ~~~~~~~~~~^~~
> lib/mpi/generic_mpih-mul1.c:37:3: error: invalid output constraint '=h'
> in asm
>                 umul_ppmm(prod_high, prod_low, s1_ptr[j], s2_limb);
>                 ^
> lib/mpi/longlong.h:653:7: note: expanded from macro 'umul_ppmm'
>              "=h" ((USItype)(w1)) \
>              ^
> 2 errors generated.
> 
> Fixes: 5ce3e312ec5c ("crypto: GnuPG based MPI lib - header files (part 2)")
> Link: https://github.com/ClangBuiltLinux/linux/issues/605
> Link: https://github.com/gpg/libgcrypt/commit/1ecbd0bca31d462719a2a6590c1d03244e76ef89
> Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
> [jk: add changelog, rebase on libgcrypt repository, reformat changed
>  line so it does not go over 80 characters]
> Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>

This is my signed-off-by for libgcrypt project, not kernel. I do not think
signed-offs can be passed from other projects in this way.

-Jussi

> [nc: Added build error and tags to commit message
>      Added Vladimir's signoff with his permission
>      Adjusted Jussi's comment to wrap at 73 characters
>      Modified commit subject to mirror MIPS64 commit
>      Removed space between defined and (__clang__)]
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
>  lib/mpi/longlong.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/mpi/longlong.h b/lib/mpi/longlong.h
> index 3bb6260d8f42..8a1507fc94dd 100644
> --- a/lib/mpi/longlong.h
> +++ b/lib/mpi/longlong.h
> @@ -639,7 +639,8 @@ do { \
>  	**************  MIPS  *****************
>  	***************************************/
>  #if defined(__mips__) && W_TYPE_SIZE == 32
> -#if (__GNUC__ >= 5) || (__GNUC__ >= 4 && __GNUC_MINOR__ >= 4)
> +#if defined(__clang__) || (__GNUC__ >= 5) || (__GNUC__ == 4 && \
> +					      __GNUC_MINOR__ >= 4)
>  #define umul_ppmm(w1, w0, u, v)			\
>  do {						\
>  	UDItype __ll = (UDItype)(u) * (v);	\
> 