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From: Adhemerval Zanella <azanella@sourceware.org>
To: glibc-cvs@sourceware.org
Subject: [glibc] LoongArch: Use builtins for ffs and ffsll
Date: Mon, 5 Feb 2024 18:39:55 +0000 (GMT) [thread overview]
Message-ID: <20240205183955.407DE38582AA@sourceware.org> (raw)
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=2e80f139376450acdb7d879d799439578a41810e
commit 2e80f139376450acdb7d879d799439578a41810e
Author: Xi Ruoyao <xry111@xry111.site>
Date: Sun Feb 4 08:27:50 2024 +0800
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:
---
sysdeps/loongarch/math-use-builtins-ffs.h | 2 ++
1 file changed, 2 insertions(+)
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
reply other threads:[~2024-02-05 18:39 UTC|newest]
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