From: Xi Ruoyao <xry111@xry111.site>
Date: Sun, 4 Feb 2024 00:27:50 +0000 (+0800)
Subject: LoongArch: Use builtins for ffs and ffsll
X-Git-Tag: glibc-2.40~422
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2e80f139376450acdb7d879d799439578a41810e;p=thirdparty%2Fglibc.git

LoongArch: Use builtins for ffs and ffsll

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>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
---

diff --git a/sysdeps/loongarch/math-use-builtins-ffs.h b/sysdeps/loongarch/math-use-builtins-ffs.h
new file mode 100644
index 00000000000..a83bb154143
--- /dev/null
+++ b/sysdeps/loongarch/math-use-builtins-ffs.h
@@ -0,0 +1,2 @@
+#define USE_FFS_BUILTIN   1
+#define USE_FFSLL_BUILTIN 1