Re: [PATCH 2/3] s390/bitops: Limit return value range of __flogr()

[Juergen Christ <jchrist@linux.ibm.com>]

> With the recent ffs() and ffs64() optimization a logical and operation was
> removed, which allows the compiler to tell that the return value range of
> both functions. This may lead to compile warnings as reported by the kernel
> test robot.
> 
> Instead of only adding the not needed mask again, also add an __assume()
> statement to tell newer compilers that they can assume a specific value
> range. This allows newer compilers to optimize the not-needed logical and
> operation away.
> 
> Also change the return type of flogr() to unsigned long and add the const
> attribute to the function.
> 
> With this the reported warning is away, and in addition the kernel image
> size is reduced by ~4kb.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202508211859.UoYsJbLN-lkp@intel.com/
> Fixes: de88e74889a3 ("s390/bitops: Slightly optimize ffs() and fls64()")
> Suggested-by: Juergen Christ <jchrist@linux.ibm.com>
> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>