mips: Use builtins for ffs and ffsll
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Commit Message
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>
---
sysdeps/mips/math-use-builtins-ffs.h | 2 ++
1 file changed, 2 insertions(+)
create mode 100644 sysdeps/mips/math-use-builtins-ffs.h
Comments
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)
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.
new file mode 100644
@@ -0,0 +1,2 @@
+#define USE_FFS_BUILTIN (__mips_isa_rev >= 1)
+#define USE_FFSLL_BUILTIN (__mips_isa_rev >= 1)