From ae4b8d6a0e0dc502e3d8307474a2e5691b7434da Mon Sep 17 00:00:00 2001
From: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Date: Fri, 25 Aug 2023 13:30:58 -0300
Subject: string: Use builtins for ffs and ffsll

It allows to remove a lot of arch-specific implementations.

Checked on x86_64, aarch64, powerpc64.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
---
 string/ffs.c   |  6 +++++-
 string/ffsll.c | 10 ++++++++--
 2 files changed, 13 insertions(+), 3 deletions(-)

(limited to 'string')

diff --git a/string/ffs.c b/string/ffs.c
index 6a05ef8386..760c2bdd8d 100644
--- a/string/ffs.c
+++ b/string/ffs.c
@@ -18,13 +18,16 @@
 #include <limits.h>
 #define ffsl __something_else
 #include <string.h>
-
 #undef	ffs
+#include <math-use-builtins.h>
 
 /* Find the first bit set in I.  */
 int
 __ffs (int i)
 {
+#if USE_FFS_BUILTIN
+  return __builtin_ffs (i);
+#else
   static const unsigned char table[] =
     {
       0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
@@ -42,6 +45,7 @@ __ffs (int i)
   a = x <= 0xffff ? (x <= 0xff ? 0 : 8) : (x <= 0xffffff ?  16 : 24);
 
   return table[x >> a] + a;
+#endif
 }
 weak_alias (__ffs, ffs)
 libc_hidden_def (__ffs)
diff --git a/string/ffsll.c b/string/ffsll.c
index 7d16250026..0ec39a0c56 100644
--- a/string/ffsll.c
+++ b/string/ffsll.c
@@ -18,20 +18,26 @@
 #include <limits.h>
 #define ffsl __something_else
 #include <string.h>
-
 #undef	ffsll
+#include <math-use-builtins.h>
+#include <libc-diag.h>
 
 /* Find the first bit set in I.  */
 int
-ffsll (long long int i)
+__ffsll (long long int i)
 {
+#if USE_FFSLL_BUILTIN
+  return __builtin_ffsll (i);
+#else
   unsigned long long int x = i & -i;
 
   if (x <= 0xffffffff)
     return ffs (i);
   else
     return 32 + ffs (i >> 32);
+#endif
 }
+weak_alias (__ffsll, ffsll)
 
 #if ULONG_MAX != UINT_MAX
 #undef ffsl
-- 
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