linux-kernel - [alobakin:bitops 8/8] lib/test_bitmap.c:904:2: error: call to __compiletime_assert_233 declared with 'error' attribute: BUILD_BUG_ON failed: !__builtin_constant

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Date:   Wed, 22 Jun 2022 13:45:30 +0800
From:   kernel test robot <lkp@...el.com>
To:     Alexander Lobakin <alexandr.lobakin@...el.com>
Cc:     llvm@...ts.linux.dev, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [alobakin:bitops 8/8] lib/test_bitmap.c:904:2: error: call to
 __compiletime_assert_233 declared with 'error' attribute: BUILD_BUG_ON
 failed: !__builtin_constant_p(res)

tree:   https://github.com/alobakin/linux bitops
head:   53dc46e3f72d9b77c9c4ec23a3261d452b3bd67a
commit: 53dc46e3f72d9b77c9c4ec23a3261d452b3bd67a [8/8] lib: test_bitmap: add compile-time optimization/evaluations assertions
config: s390-randconfig-r044-20220622 (https://download.01.org/0day-ci/archive/20220622/202206221354.8jzbVLLL-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 8b8d126598ce7bd5243da7f94f69fa1104288bee)
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 s390 cross compiling tool for clang build
        # apt-get install binutils-s390x-linux-gnu
        # https://github.com/alobakin/linux/commit/53dc46e3f72d9b77c9c4ec23a3261d452b3bd67a
        git remote add alobakin https://github.com/alobakin/linux
        git fetch --no-tags alobakin bitops
        git checkout 53dc46e3f72d9b77c9c4ec23a3261d452b3bd67a
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash lib/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@...el.com>

All errors (new ones prefixed by >>):

>> lib/test_bitmap.c:904:2: error: call to __compiletime_assert_233 declared with 'error' attribute: BUILD_BUG_ON failed: !__builtin_constant_p(res)
           BUILD_BUG_ON(!__builtin_constant_p(res));
           ^
   include/linux/build_bug.h:50:2: note: expanded from macro 'BUILD_BUG_ON'
           BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
           ^
   include/linux/build_bug.h:39:37: note: expanded from macro 'BUILD_BUG_ON_MSG'
   #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
                                       ^
   include/linux/compiler_types.h:352:2: note: expanded from macro 'compiletime_assert'
           _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
           ^
   include/linux/compiler_types.h:340:2: note: expanded from macro '_compiletime_assert'
           __compiletime_assert(condition, msg, prefix, suffix)
           ^
   include/linux/compiler_types.h:333:4: note: expanded from macro '__compiletime_assert'
                           prefix ## suffix();                             \
                           ^
   <scratch space>:180:1: note: expanded from here
   __compiletime_assert_233
   ^
   1 error generated.


vim +/error +904 lib/test_bitmap.c

   871	
   872	static void __init test_bitmap_const_eval(void)
   873	{
   874		DECLARE_BITMAP(bitmap, BITS_PER_LONG);
   875		unsigned long initvar = BIT(2);
   876		unsigned long bitopvar = 0;
   877		unsigned long var = 0;
   878		int res;
   879	
   880		/*
   881		 * Compilers must be able to optimize all of those to compile-time
   882		 * constants on any supported optimization level (-O2, -Os) and any
   883		 * architecture. Otherwise, trigger a build bug.
   884		 * The whole function gets optimized out then, there's nothing to do
   885		 * in runtime.
   886		 */
   887	
   888		/* Equals to `unsigned long bitmap[1] = { BIT(5), }` */
   889		bitmap_clear(bitmap, 0, BITS_PER_LONG);
   890		if (!test_bit(7, bitmap))
   891			bitmap_set(bitmap, 5, 1);
   892	
   893		/* Equals to `unsigned long bitopvar = BIT(20)` */
   894		__change_bit(31, &bitopvar);
   895		bitmap_shift_right(&bitopvar, &bitopvar, 11, BITS_PER_LONG);
   896	
   897		/* Equals to `unsigned long var = BIT(25)` */
   898		var |= BIT(25);
   899		if (var & BIT(0))
   900			var ^= GENMASK(9, 6);
   901	
   902		/* __const_hweight<32|64>(BIT(5)) == 1 */
   903		res = bitmap_weight(bitmap, 20);
 > 904		BUILD_BUG_ON(!__builtin_constant_p(res));
   905	
   906		/* !(BIT(31) & BIT(18)) == 1 */
   907		res = !test_bit(18, &bitopvar);
   908		BUILD_BUG_ON(!__builtin_constant_p(res));
   909	
   910		/* BIT(2) & GENMASK(14, 8) == 0 */
   911		BUILD_BUG_ON(!__builtin_constant_p(initvar & GENMASK(14, 8)));
   912		/* ~BIT(25) */
   913		BUILD_BUG_ON(!__builtin_constant_p(~var));
   914	}
   915	

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