Re: [RESEND,PATCH] ARM: fix __div64_32() error when compiling with clang

[kernel test robot]

Hi Antony,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v5.10-rc5 next-20201124]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Antony-Yu/ARM-fix-__div64_32-error-when-compiling-with-clang/20201123-154454
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 418baf2c28f3473039f2f7377760bd8f6897ae18
config: arm-randconfig-r036-20201124 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project df9ae5992889560a8f3c6760b54d5051b47c7bf5)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install arm cross compiling tool for clang build
        # apt-get install binutils-arm-linux-gnueabi
        # https://github.com/0day-ci/linux/commit/83df1f983ed4219556020bf30cc819e66bb7e69c
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Antony-Yu/ARM-fix-__div64_32-error-when-compiling-with-clang/20201123-154454
        git checkout 83df1f983ed4219556020bf30cc819e66bb7e69c
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All errors (new ones prefixed by >>):

   drivers/tty/serial/imx.c:359:19: warning: unused function 'imx_uart_is_imx21' [-Wunused-function]
   static inline int imx_uart_is_imx21(struct imx_port *sport)
                     ^
   drivers/tty/serial/imx.c:364:19: warning: unused function 'imx_uart_is_imx53' [-Wunused-function]
   static inline int imx_uart_is_imx53(struct imx_port *sport)
                     ^
   drivers/tty/serial/imx.c:369:19: warning: unused function 'imx_uart_is_imx6q' [-Wunused-function]
   static inline int imx_uart_is_imx6q(struct imx_port *sport)
                     ^
   In file included from drivers/tty/serial/imx.c:11:
   In file included from include/linux/module.h:12:
   In file included from include/linux/list.h:9:
   In file included from include/linux/kernel.h:19:
>> arch/arm/include/asm/div64.h:39:2: error: multiple outputs to hard register: r0
           asm(    __asmeq("%0", __xh)
           ^
   3 warnings and 1 error generated.
--
   In file included from drivers/gpu/drm/tegra/dc.c:7:
   In file included from include/linux/clk.h:13:
   In file included from include/linux/kernel.h:19:
>> arch/arm/include/asm/div64.h:39:2: error: multiple outputs to hard register: r0
           asm(    __asmeq("%0", __xh)
           ^
   1 error generated.

vim +39 arch/arm/include/asm/div64.h

^1da177e4c3f415 include/asm-arm/div64.h      Linus Torvalds 2005-04-16  32  
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02  33  static inline uint32_t __div64_32(uint64_t *n, uint32_t base)
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02  34  {
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02  35  	register unsigned int __base      asm("r4") = base;
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02  36  	register unsigned long long __n   asm("r0") = *n;
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02  37  	register unsigned long long __res asm("r2");
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02  38  	register unsigned int __rem       asm(__xh);
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02 @39  	asm(	__asmeq("%0", __xh)
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02  40  		__asmeq("%1", "r2")
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02  41  		__asmeq("%2", "r0")
83df1f983ed4219 arch/arm/include/asm/div64.h Antony Yu      2020-11-23  42  		__asmeq("%3", "r0")
83df1f983ed4219 arch/arm/include/asm/div64.h Antony Yu      2020-11-23  43  		__asmeq("%4", "r4")
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02  44  		"bl	__do_div64"
83df1f983ed4219 arch/arm/include/asm/div64.h Antony Yu      2020-11-23  45  		: "=r" (__rem), "=r" (__res), "=r" (__n)
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02  46  		: "r" (__n), "r" (__base)
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02  47  		: "ip", "lr", "cc");
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02  48  	*n = __res;
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02  49  	return __rem;
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02  50  }
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02  51  #define __div64_32 __div64_32
040b323b5012b55 arch/arm/include/asm/div64.h Nicolas Pitre  2015-11-02  52  

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