[PATCH] LoongArch: Use builtins for ffs and ffsll

[Xi Ruoyao]

On LoongArch GCC compiles __builtin_ffs{,ll} to basically
`(x ? __builtin_ctz (x) : -1) + 1`.  Since a hardware ctz instruction is
available, this is much better than the table-driven generic
implementation.

Tested on loongarch64.

Signed-off-by: Xi Ruoyao <xry111@xry111.site>
---
 sysdeps/loongarch/math-use-builtins-ffs.h | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 sysdeps/loongarch/math-use-builtins-ffs.h

diff --git a/sysdeps/loongarch/math-use-builtins-ffs.h b/sysdeps/loongarch/math-use-builtins-ffs.h
new file mode 100644
index 0000000000..a83bb15414
--- /dev/null
+++ b/sysdeps/loongarch/math-use-builtins-ffs.h
@@ -0,0 +1,2 @@
+#define USE_FFS_BUILTIN   1
+#define USE_FFSLL_BUILTIN 1
-- 
2.43.0