Re: [PATCH] mips: Use builtins for ffs and ffsll

[Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>]

On 05/02/24 11:19, Adhemerval Zanella Netto wrote:
> 
> 
> On 04/02/24 07:11, Junxian Zhu wrote:
>> From: Junxian Zhu <zhujunxian@oss.cipunited.com>
>>
>> __builtin_ffs{,ll} basically on __builtin_ctz{,ll} in MIPS GCC compiler.
>> The hardware ctz instructions were available after MIPS{32,64} Release1. By using builtin ctz. It can also reduce code size of ffs/ffsll.
>>
>> Checked on mips o32. mips64.
>>
>> Signed-off-by: Junxian Zhu <zhujunxian@oss.cipunited.com>
> 
> LGTM, thanks.
> 
> Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
> 
>> ---
>>  sysdeps/mips/math-use-builtins-ffs.h | 2 ++
>>  1 file changed, 2 insertions(+)
>>  create mode 100644 sysdeps/mips/math-use-builtins-ffs.h
>>
>> diff --git a/sysdeps/mips/math-use-builtins-ffs.h b/sysdeps/mips/math-use-builtins-ffs.h
>> new file mode 100644
>> index 0000000000..78b3f14fae
>> --- /dev/null
>> +++ b/sysdeps/mips/math-use-builtins-ffs.h
>> @@ -0,0 +1,2 @@
>> +#define USE_FFS_BUILTIN (__mips_isa_rev >= 1)
>> +#define USE_FFSLL_BUILTIN (__mips_isa_rev >= 1)

In fact you need to include <sysdep.h> since gcc only defines __mips_isa_rev
for -mips32 or higher.