diff mbox series

[v3] string: Use builtins for ffs and ffsll

Message ID 20230825163058.2667528-1-adhemerval.zanella@linaro.org
State New
Headers show
Series [v3] string: Use builtins for ffs and ffsll | expand

Commit Message

Adhemerval Zanella Netto Aug. 25, 2023, 4:30 p.m. UTC
It allows to remove a lot of arch-specific implementations.

Checked on x86_64, aarch64, powerpc64.
--
Changes from v2:
* Fix arm math-use-builtins-ffs.h placement.
---
 string/ffs.c                                |  6 +-
 string/ffsll.c                              | 10 ++-
 sysdeps/aarch64/math-use-builtins-ffs.h     |  2 +
 sysdeps/alpha/alphaev67/ffs.S               | 51 ------------
 sysdeps/alpha/alphaev67/ffsll.S             | 44 ----------
 sysdeps/alpha/ffs.S                         | 90 ---------------------
 sysdeps/alpha/ffsll.S                       |  1 -
 sysdeps/alpha/math-use-builtins-ffs.h       |  7 ++
 sysdeps/arc/math-use-builtins-ffs.h         |  2 +
 sysdeps/arm/armv6t2/ffs.S                   | 36 ---------
 sysdeps/arm/armv6t2/ffsll.S                 | 50 ------------
 sysdeps/arm/armv6t2/math-use-builtins-ffs.h |  2 +
 sysdeps/generic/math-use-builtins-ffs.h     |  2 +
 sysdeps/generic/math-use-builtins.h         |  1 +
 sysdeps/i386/ffs.c                          | 49 -----------
 sysdeps/i386/i686/ffs.c                     | 47 -----------
 sysdeps/i386/math-use-builtins-ffs.h        |  2 +
 sysdeps/ia64/math-use-builtins-ffs.h        |  2 +
 sysdeps/m68k/ffs.c                          | 46 -----------
 sysdeps/m68k/math-use-builtins-ffs.h        |  7 ++
 sysdeps/powerpc/ffs.c                       | 46 -----------
 sysdeps/powerpc/math-use-builtins-ffs.h     |  6 ++
 sysdeps/powerpc/powerpc64/ffsll.c           | 36 ---------
 sysdeps/s390/ffs.c                          | 69 ----------------
 sysdeps/x86_64/ffs.c                        | 38 ---------
 sysdeps/x86_64/ffsll.c                      | 41 ----------
 sysdeps/x86_64/math-use-builtins-ffs.h      |  2 +
 sysdeps/x86_64/x32/ffs.c                    |  4 -
 28 files changed, 48 insertions(+), 651 deletions(-)
 create mode 100644 sysdeps/aarch64/math-use-builtins-ffs.h
 delete mode 100644 sysdeps/alpha/alphaev67/ffs.S
 delete mode 100644 sysdeps/alpha/alphaev67/ffsll.S
 delete mode 100644 sysdeps/alpha/ffs.S
 delete mode 100644 sysdeps/alpha/ffsll.S
 create mode 100644 sysdeps/alpha/math-use-builtins-ffs.h
 create mode 100644 sysdeps/arc/math-use-builtins-ffs.h
 delete mode 100644 sysdeps/arm/armv6t2/ffs.S
 delete mode 100644 sysdeps/arm/armv6t2/ffsll.S
 create mode 100644 sysdeps/arm/armv6t2/math-use-builtins-ffs.h
 create mode 100644 sysdeps/generic/math-use-builtins-ffs.h
 delete mode 100644 sysdeps/i386/ffs.c
 delete mode 100644 sysdeps/i386/i686/ffs.c
 create mode 100644 sysdeps/i386/math-use-builtins-ffs.h
 create mode 100644 sysdeps/ia64/math-use-builtins-ffs.h
 delete mode 100644 sysdeps/m68k/ffs.c
 create mode 100644 sysdeps/m68k/math-use-builtins-ffs.h
 delete mode 100644 sysdeps/powerpc/ffs.c
 create mode 100644 sysdeps/powerpc/math-use-builtins-ffs.h
 delete mode 100644 sysdeps/powerpc/powerpc64/ffsll.c
 delete mode 100644 sysdeps/s390/ffs.c
 delete mode 100644 sysdeps/x86_64/ffs.c
 delete mode 100644 sysdeps/x86_64/ffsll.c
 create mode 100644 sysdeps/x86_64/math-use-builtins-ffs.h
 delete mode 100644 sysdeps/x86_64/x32/ffs.c

Comments

Carlos O'Donell Jan. 10, 2024, 7:19 p.m. UTC | #1
On 8/25/23 12:30, Adhemerval Zanella via Libc-alpha wrote:
> It allows to remove a lot of arch-specific implementations.

The ffs/ffsll issue came up again in downstream discussions.

I read through the initial patch, the following discussion, and points
from Florian, Andreas, Wilco, Richard, Andrew etc. It seems to me that
there is consensus that complete removal is the best overall long term
option.

Generated code for x86_64 looks like this (without CET on):

0000000000095460 <__ffs>:
__GI___ffs():
/mnt/ssd/carlos/src/glibc-review/string/ffs.c:29
   95460:       0f bc c7                bsf    %edi,%eax
   95463:       ba ff ff ff ff          mov    $0xffffffff,%edx
   95468:       0f 44 c2                cmove  %edx,%eax
   9546b:       83 c0 01                add    $0x1,%eax
/mnt/ssd/carlos/src/glibc-review/string/ffs.c:49
   9546e:       c3                      ret    
__GI_ffs():
   9546f:       90                      nop

0000000000095470 <ffsl>:
__ffsll():
/mnt/ssd/carlos/src/glibc-review/string/ffsll.c:30
   95470:       48 0f bc ff             bsf    %rdi,%rdi
   95474:       48 c7 c0 ff ff ff ff    mov    $0xffffffffffffffff,%rax
   9547b:       48 0f 44 f8             cmove  %rax,%rdi
   9547f:       8d 47 01                lea    0x1(%rdi),%eax
/mnt/ssd/carlos/src/glibc-review/string/ffsll.c:39
   95482:       c3                      ret    
   95483:       66 2e 0f 1f 84 00 00    cs nopw 0x0(%rax,%rax,1)
   9548a:       00 00 00 
   9548d:       0f 1f 00                nopl   (%rax)

This looks about what I would expect.

Performance critical applications should allow the compiler to use the
builtin and much much more.

OK for glibc 2.40 (not the upcoming 2.39 release).

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
 
> Checked on x86_64, aarch64, powerpc64.
> --
> Changes from v2:
> * Fix arm math-use-builtins-ffs.h placement.
> ---
>  string/ffs.c                                |  6 +-
>  string/ffsll.c                              | 10 ++-
>  sysdeps/aarch64/math-use-builtins-ffs.h     |  2 +
>  sysdeps/alpha/alphaev67/ffs.S               | 51 ------------
>  sysdeps/alpha/alphaev67/ffsll.S             | 44 ----------
>  sysdeps/alpha/ffs.S                         | 90 ---------------------
>  sysdeps/alpha/ffsll.S                       |  1 -
>  sysdeps/alpha/math-use-builtins-ffs.h       |  7 ++
>  sysdeps/arc/math-use-builtins-ffs.h         |  2 +
>  sysdeps/arm/armv6t2/ffs.S                   | 36 ---------
>  sysdeps/arm/armv6t2/ffsll.S                 | 50 ------------
>  sysdeps/arm/armv6t2/math-use-builtins-ffs.h |  2 +
>  sysdeps/generic/math-use-builtins-ffs.h     |  2 +
>  sysdeps/generic/math-use-builtins.h         |  1 +
>  sysdeps/i386/ffs.c                          | 49 -----------
>  sysdeps/i386/i686/ffs.c                     | 47 -----------
>  sysdeps/i386/math-use-builtins-ffs.h        |  2 +
>  sysdeps/ia64/math-use-builtins-ffs.h        |  2 +
>  sysdeps/m68k/ffs.c                          | 46 -----------
>  sysdeps/m68k/math-use-builtins-ffs.h        |  7 ++
>  sysdeps/powerpc/ffs.c                       | 46 -----------
>  sysdeps/powerpc/math-use-builtins-ffs.h     |  6 ++
>  sysdeps/powerpc/powerpc64/ffsll.c           | 36 ---------
>  sysdeps/s390/ffs.c                          | 69 ----------------
>  sysdeps/x86_64/ffs.c                        | 38 ---------
>  sysdeps/x86_64/ffsll.c                      | 41 ----------
>  sysdeps/x86_64/math-use-builtins-ffs.h      |  2 +
>  sysdeps/x86_64/x32/ffs.c                    |  4 -
>  28 files changed, 48 insertions(+), 651 deletions(-)
>  create mode 100644 sysdeps/aarch64/math-use-builtins-ffs.h
>  delete mode 100644 sysdeps/alpha/alphaev67/ffs.S
>  delete mode 100644 sysdeps/alpha/alphaev67/ffsll.S
>  delete mode 100644 sysdeps/alpha/ffs.S
>  delete mode 100644 sysdeps/alpha/ffsll.S
>  create mode 100644 sysdeps/alpha/math-use-builtins-ffs.h
>  create mode 100644 sysdeps/arc/math-use-builtins-ffs.h
>  delete mode 100644 sysdeps/arm/armv6t2/ffs.S
>  delete mode 100644 sysdeps/arm/armv6t2/ffsll.S
>  create mode 100644 sysdeps/arm/armv6t2/math-use-builtins-ffs.h
>  create mode 100644 sysdeps/generic/math-use-builtins-ffs.h
>  delete mode 100644 sysdeps/i386/ffs.c
>  delete mode 100644 sysdeps/i386/i686/ffs.c
>  create mode 100644 sysdeps/i386/math-use-builtins-ffs.h
>  create mode 100644 sysdeps/ia64/math-use-builtins-ffs.h
>  delete mode 100644 sysdeps/m68k/ffs.c
>  create mode 100644 sysdeps/m68k/math-use-builtins-ffs.h
>  delete mode 100644 sysdeps/powerpc/ffs.c
>  create mode 100644 sysdeps/powerpc/math-use-builtins-ffs.h
>  delete mode 100644 sysdeps/powerpc/powerpc64/ffsll.c
>  delete mode 100644 sysdeps/s390/ffs.c
>  delete mode 100644 sysdeps/x86_64/ffs.c
>  delete mode 100644 sysdeps/x86_64/ffsll.c
>  create mode 100644 sysdeps/x86_64/math-use-builtins-ffs.h
>  delete mode 100644 sysdeps/x86_64/x32/ffs.c
> 
> diff --git a/string/ffs.c b/string/ffs.c
> index bf58f0b7ca..8302ae8420 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 0cc461a1cf..2315fe1bd7 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
> diff --git a/sysdeps/aarch64/math-use-builtins-ffs.h b/sysdeps/aarch64/math-use-builtins-ffs.h
> new file mode 100644
> index 0000000000..a83bb15414
> --- /dev/null
> +++ b/sysdeps/aarch64/math-use-builtins-ffs.h
> @@ -0,0 +1,2 @@
> +#define USE_FFS_BUILTIN   1
> +#define USE_FFSLL_BUILTIN 1
> diff --git a/sysdeps/alpha/alphaev67/ffs.S b/sysdeps/alpha/alphaev67/ffs.S
> deleted file mode 100644
> index 48361bd8c5..0000000000
> --- a/sysdeps/alpha/alphaev67/ffs.S
> +++ /dev/null
> @@ -1,51 +0,0 @@
> -/* Copyright (C) 2000-2023 Free Software Foundation, Inc.
> -   This file is part of the GNU C Library.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library.  If not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -/* Finds the first bit set in an integer.  */
> -
> -#include <sysdep.h>
> -
> -	.arch ev6
> -	.set noreorder
> -	.set noat
> -
> -
> -ENTRY(__ffs)
> -#ifdef PROF
> -	ldgp	gp, 0(pv)
> -	lda	AT, _mcount
> -	jsr	AT, (AT), _mcount
> -	.prologue 1
> -#else
> -	.prologue 0
> -#endif
> -
> -	zap	$16, 0xF0, $16
> -	cttz	$16, $0
> -	addq	$0, 1, $0
> -	cmoveq	$16, 0, $0
> -
> -	nop
> -	nop
> -	nop
> -	ret
> -
> -END(__ffs)
> -
> -weak_alias (__ffs, ffs)
> -libc_hidden_def (__ffs)
> -libc_hidden_builtin_def (ffs)
> diff --git a/sysdeps/alpha/alphaev67/ffsll.S b/sysdeps/alpha/alphaev67/ffsll.S
> deleted file mode 100644
> index 52f406ec32..0000000000
> --- a/sysdeps/alpha/alphaev67/ffsll.S
> +++ /dev/null
> @@ -1,44 +0,0 @@
> -/* Copyright (C) 2000-2023 Free Software Foundation, Inc.
> -   This file is part of the GNU C Library.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library.  If not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -/* Finds the first bit set in a long.  */
> -
> -#include <sysdep.h>
> -
> -	.arch ev6
> -	.set noreorder
> -	.set noat
> -
> -ENTRY(ffsl)
> -#ifdef PROF
> -	ldgp	gp, 0(pv)
> -	lda	AT, _mcount
> -	jsr	AT, (AT), _mcount
> -	.prologue 1
> -#else
> -	.prologue 0
> -#endif
> -
> -	cttz	$16, $0
> -	addq	$0, 1, $0
> -	cmoveq	$16, 0, $0
> -	ret
> -
> -END(ffsl)
> -
> -weak_extern (ffsl)
> -weak_alias (ffsl, ffsll)
> diff --git a/sysdeps/alpha/ffs.S b/sysdeps/alpha/ffs.S
> deleted file mode 100644
> index 047fd60352..0000000000
> --- a/sysdeps/alpha/ffs.S
> +++ /dev/null
> @@ -1,90 +0,0 @@
> -/* Copyright (C) 1996-2023 Free Software Foundation, Inc.
> -   This file is part of the GNU C Library.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library.  If not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -/* Finds the first bit set in an integer.  Optimized for the Alpha
> -   architecture.  */
> -
> -#include <sysdep.h>
> -
> -	.set noreorder
> -	.set noat
> -
> -
> -ENTRY(__ffs)
> -#ifdef PROF
> -	ldgp	gp, 0(pv)
> -	lda	AT, _mcount
> -	jsr	AT, (AT), _mcount
> -	.prologue 1
> -	zap	$16, 0xF0, $16
> -	br	$ffsl..ng
> -#else
> -	.prologue 0
> -	zap	$16, 0xF0, $16
> -	# FALLTHRU
> -#endif
> -END(__ffs)
> -
> -	.align 4
> -ENTRY(ffsl)
> -#ifdef PROF
> -	ldgp	gp, 0(pv)
> -	lda	AT, _mcount
> -	jsr	AT, (AT), _mcount
> -	.prologue 1
> -$ffsl..ng:
> -#else
> -	.prologue 0
> -#endif
> -	not	$16, $1		# e0    :
> -	ldi	$2, -1		# .. e1 :
> -	cmpbge	$1, $2, $3	# e0    : bit N == 1 for byte N == 0
> -	clr	$0		# .. e1 :
> -	addq	$3, 1, $4	# e0    :
> -	bic	$4, $3, $3	# e1    : bit N == 1 for first byte N != 0
> -	and	$3, 0xF0, $4	# e0    :
> -	and	$3, 0xCC, $5	# .. e1 :
> -	and	$3, 0xAA, $6	# e0    :
> -	cmovne	$4, 4, $0	# .. e1 :
> -	cmovne	$5, 2, $5	# e0    :
> -	cmovne  $6, 1, $6	# .. e1 :
> -	addl	$0, $5, $0	# e0    :
> -	addl	$0, $6, $0	# e1    : $0 == N
> -	extbl	$16, $0, $1	# e0    : $1 == byte N
> -	ldi	$2, 1		# .. e1 :
> -	negq	$1, $3		# e0    :
> -	and	$3, $1, $3	# e1    : bit N == least bit set of byte N
> -	and	$3, 0xF0, $4	# e0    :
> -	and	$3, 0xCC, $5	# .. e1 :
> -	and	$3, 0xAA, $6	# e0    :
> -	cmovne	$4, 5, $2	# .. e1 :
> -	cmovne	$5, 2, $5	# e0    :
> -	cmovne	$6, 1, $6	# .. e1 :
> -	s8addl	$0, $2, $0	# e0    : mult byte ofs by 8 and sum
> -	addl	$5, $6, $5	# .. e1 :
> -	addl	$0, $5, $0	# e0    :
> -	nop			# .. e1 :
> -	cmoveq	$16, 0, $0	# e0    : trap input == 0 case.
> -	ret			# .. e1 : 18
> -
> -END(ffsl)
> -
> -weak_alias (__ffs, ffs)
> -libc_hidden_def (__ffs)
> -libc_hidden_builtin_def (ffs)
> -weak_extern (ffsl)
> -weak_alias (ffsl, ffsll)
> diff --git a/sysdeps/alpha/ffsll.S b/sysdeps/alpha/ffsll.S
> deleted file mode 100644
> index b2f46d899c..0000000000
> --- a/sysdeps/alpha/ffsll.S
> +++ /dev/null
> @@ -1 +0,0 @@
> -/* This function is defined in ffs.S.  */
> diff --git a/sysdeps/alpha/math-use-builtins-ffs.h b/sysdeps/alpha/math-use-builtins-ffs.h
> new file mode 100644
> index 0000000000..9925e374ac
> --- /dev/null
> +++ b/sysdeps/alpha/math-use-builtins-ffs.h
> @@ -0,0 +1,7 @@
> +#ifdef __alpha_cix__
> +# define USE_FFS_BUILTIN   1
> +# define USE_FFSLL_BUILTIN 1
> +#else
> +# define USE_FFS_BUILTIN   0
> +# define USE_FFSLL_BUILTIN 0
> +#endif
> diff --git a/sysdeps/arc/math-use-builtins-ffs.h b/sysdeps/arc/math-use-builtins-ffs.h
> new file mode 100644
> index 0000000000..c0f108c264
> --- /dev/null
> +++ b/sysdeps/arc/math-use-builtins-ffs.h
> @@ -0,0 +1,2 @@
> +#define USE_FFS_BUILTIN   1
> +#define USE_FFSLL_BUILTIN 0
> diff --git a/sysdeps/arm/armv6t2/ffs.S b/sysdeps/arm/armv6t2/ffs.S
> deleted file mode 100644
> index 870957a4bb..0000000000
> --- a/sysdeps/arm/armv6t2/ffs.S
> +++ /dev/null
> @@ -1,36 +0,0 @@
> -/* ffs -- find first set bit in an int, from least significant end.
> -   Copyright (C) 2013-2023 Free Software Foundation, Inc.
> -   This file is part of the GNU C Library.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library.  If not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -#include <sysdep.h>
> -
> -	.syntax unified
> -	.text
> -
> -ENTRY (__ffs)
> -	cmp	r0, #0
> -	rbit	r0, r0
> -	itt	ne
> -	clzne	r0, r0
> -	addne	r0, r0, #1
> -	bx	lr
> -END (__ffs)
> -
> -weak_alias (__ffs, ffs)
> -weak_alias (__ffs, ffsl)
> -libc_hidden_def (__ffs)
> -libc_hidden_builtin_def (ffs)
> diff --git a/sysdeps/arm/armv6t2/ffsll.S b/sysdeps/arm/armv6t2/ffsll.S
> deleted file mode 100644
> index bc3cbf81b0..0000000000
> --- a/sysdeps/arm/armv6t2/ffsll.S
> +++ /dev/null
> @@ -1,50 +0,0 @@
> -/* ffsll -- find first set bit in a long long, from least significant end.
> -   Copyright (C) 2013-2023 Free Software Foundation, Inc.
> -   This file is part of the GNU C Library.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library.  If not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -#include <sysdep.h>
> -
> -	.syntax unified
> -	.text
> -
> -ENTRY (ffsll)
> -	@ If low part is 0, operate on the high part.  Ensure that the
> -	@ word on which we operate is in r0.  Set r2 to the bit offset
> -	@ of the word being considered.  Set the flags for the word
> -	@ being operated on.
> -#ifdef __ARMEL__
> -	cmp	r0, #0
> -	itee	ne
> -	movne	r2, #0
> -	moveq	r2, #32
> -	movseq	r0, r1
> -#else
> -	cmp	r1, #0
> -	ittee	ne
> -	movne	r2, #0
> -	movne	r0, r1
> -	moveq	r2, #32
> -	cmpeq	r0, #0
> -#endif
> -	@ Perform the ffs on r0.
> -	rbit	r0, r0
> -	ittt	ne
> -	clzne	r0, r0
> -	addne	r2, r2, #1
> -	addne	r0, r0, r2
> -	bx	lr
> -END (ffsll)
> diff --git a/sysdeps/arm/armv6t2/math-use-builtins-ffs.h b/sysdeps/arm/armv6t2/math-use-builtins-ffs.h
> new file mode 100644
> index 0000000000..c0f108c264
> --- /dev/null
> +++ b/sysdeps/arm/armv6t2/math-use-builtins-ffs.h
> @@ -0,0 +1,2 @@
> +#define USE_FFS_BUILTIN   1
> +#define USE_FFSLL_BUILTIN 0
> diff --git a/sysdeps/generic/math-use-builtins-ffs.h b/sysdeps/generic/math-use-builtins-ffs.h
> new file mode 100644
> index 0000000000..add8537470
> --- /dev/null
> +++ b/sysdeps/generic/math-use-builtins-ffs.h
> @@ -0,0 +1,2 @@
> +#define USE_FFS_BUILTIN   0
> +#define USE_FFSLL_BUILTIN 0
> diff --git a/sysdeps/generic/math-use-builtins.h b/sysdeps/generic/math-use-builtins.h
> index 04b1d0d5ab..038eb2c523 100644
> --- a/sysdeps/generic/math-use-builtins.h
> +++ b/sysdeps/generic/math-use-builtins.h
> @@ -40,5 +40,6 @@
>  #include <math-use-builtins-lrint.h>
>  #include <math-use-builtins-llrint.h>
>  #include <math-use-builtins-logb.h>
> +#include <math-use-builtins-ffs.h>
>  
>  #endif /* MATH_USE_BUILTINS_H  */
> diff --git a/sysdeps/i386/ffs.c b/sysdeps/i386/ffs.c
> deleted file mode 100644
> index b8e798420b..0000000000
> --- a/sysdeps/i386/ffs.c
> +++ /dev/null
> @@ -1,49 +0,0 @@
> -/* ffs -- find first set bit in a word, counted from least significant end.
> -   For Intel 80x86, x>=3.
> -   This file is part of the GNU C Library.
> -   Copyright (C) 1991-2023 Free Software Foundation, Inc.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library; if not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -#define ffsl __something_else
> -#include <string.h>
> -
> -#undef	ffs
> -
> -#ifdef	__GNUC__
> -
> -int
> -__ffs (int x)
> -{
> -  int cnt;
> -  int tmp;
> -
> -  asm ("xorl %0,%0\n"		/* Set CNT to zero.  */
> -       "bsfl %2,%1\n"		/* Count low bits in X and store in %1.  */
> -       "jz 1f\n"		/* Jump if OK, i.e. X was non-zero.  */
> -       "leal 1(%1),%0\n"	/* Return bsfl-result plus one on %0.  */
> -       "1:" : "=&a" (cnt), "=r" (tmp) : "rm" (x));
> -
> -  return cnt;
> -}
> -weak_alias (__ffs, ffs)
> -libc_hidden_def (__ffs)
> -libc_hidden_builtin_def (ffs)
> -#undef ffsl
> -weak_alias (__ffs, ffsl)
> -
> -#else
> -#include <string/ffs.c>
> -#endif
> diff --git a/sysdeps/i386/i686/ffs.c b/sysdeps/i386/i686/ffs.c
> deleted file mode 100644
> index a522077cfe..0000000000
> --- a/sysdeps/i386/i686/ffs.c
> +++ /dev/null
> @@ -1,47 +0,0 @@
> -/* ffs -- find first set bit in a word, counted from least significant end.
> -   For Intel 80x86, x>=6.
> -   This file is part of the GNU C Library.
> -   Copyright (C) 1991-2023 Free Software Foundation, Inc.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library; if not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -#define ffsl __something_else
> -#include <string.h>
> -
> -#undef	ffs
> -
> -#ifdef	__GNUC__
> -
> -int
> -__ffs (int x)
> -{
> -  int cnt;
> -  int tmp;
> -
> -  asm ("bsfl %2,%0\n"		/* Count low bits in X and store in %1.  */
> -       "cmovel %1,%0\n"		/* If number was zero, use -1 as result.  */
> -       : "=&r" (cnt), "=r" (tmp) : "rm" (x), "1" (-1));
> -
> -  return cnt + 1;
> -}
> -weak_alias (__ffs, ffs)
> -libc_hidden_def (__ffs)
> -libc_hidden_builtin_def (ffs)
> -#undef ffsl
> -weak_alias (__ffs, ffsl)
> -
> -#else
> -#include <string/ffs.c>
> -#endif
> diff --git a/sysdeps/i386/math-use-builtins-ffs.h b/sysdeps/i386/math-use-builtins-ffs.h
> new file mode 100644
> index 0000000000..c0f108c264
> --- /dev/null
> +++ b/sysdeps/i386/math-use-builtins-ffs.h
> @@ -0,0 +1,2 @@
> +#define USE_FFS_BUILTIN   1
> +#define USE_FFSLL_BUILTIN 0
> diff --git a/sysdeps/ia64/math-use-builtins-ffs.h b/sysdeps/ia64/math-use-builtins-ffs.h
> new file mode 100644
> index 0000000000..a83bb15414
> --- /dev/null
> +++ b/sysdeps/ia64/math-use-builtins-ffs.h
> @@ -0,0 +1,2 @@
> +#define USE_FFS_BUILTIN   1
> +#define USE_FFSLL_BUILTIN 1
> diff --git a/sysdeps/m68k/ffs.c b/sysdeps/m68k/ffs.c
> deleted file mode 100644
> index 4415bb0cff..0000000000
> --- a/sysdeps/m68k/ffs.c
> +++ /dev/null
> @@ -1,46 +0,0 @@
> -/* ffs -- find first set bit in a word, counted from least significant end.
> -   For mc68020, mc68030, mc68040.
> -   This file is part of the GNU C Library.
> -   Copyright (C) 1991-2023 Free Software Foundation, Inc.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library.  If not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -#define ffsl __something_else
> -#include <string.h>
> -
> -#undef	ffs
> -
> -#if	defined (__GNUC__) && defined (__mc68020__)
> -
> -int
> -__ffs (int x)
> -{
> -  int cnt;
> -
> -  asm ("bfffo %1{#0:#0},%0" : "=d" (cnt) : "dm" (x & -x));
> -
> -  return 32 - cnt;
> -}
> -weak_alias (__ffs, ffs)
> -libc_hidden_def (__ffs)
> -libc_hidden_builtin_def (ffs)
> -#undef ffsl
> -weak_alias (__ffs, ffsl)
> -
> -#else
> -
> -#include <string/ffs.c>
> -
> -#endif
> diff --git a/sysdeps/m68k/math-use-builtins-ffs.h b/sysdeps/m68k/math-use-builtins-ffs.h
> new file mode 100644
> index 0000000000..4e1d994453
> --- /dev/null
> +++ b/sysdeps/m68k/math-use-builtins-ffs.h
> @@ -0,0 +1,7 @@
> +#if defined __mc68020__ || defined __mc68030__ || defined __mc68040__ \
> +    || defined __mc68060__
> +# define USE_FFS_BUILTIN  1
> +#else
> +# define USE_FFS_BUILTIN  0
> +#endif
> +#define USE_FFSLL_BUILTIN 0
> diff --git a/sysdeps/powerpc/ffs.c b/sysdeps/powerpc/ffs.c
> deleted file mode 100644
> index 0a046dab99..0000000000
> --- a/sysdeps/powerpc/ffs.c
> +++ /dev/null
> @@ -1,46 +0,0 @@
> -/* Find first set bit in a word, counted from least significant end.
> -   For PowerPC.
> -   Copyright (C) 1991-2023 Free Software Foundation, Inc.
> -   This file is part of the GNU C Library.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library; if not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -#define ffsl __something_else
> -#include <limits.h>
> -#include <string.h>
> -
> -#undef	ffs
> -
> -#ifdef 	__GNUC__
> -
> -int
> -__ffs (int x)
> -{
> -  int cnt;
> -
> -  asm ("cntlzw %0,%1" : "=r" (cnt) : "r" (x & -x));
> -  return 32 - cnt;
> -}
> -weak_alias (__ffs, ffs)
> -libc_hidden_def (__ffs)
> -libc_hidden_builtin_def (ffs)
> -#if ULONG_MAX == UINT_MAX
> -#undef ffsl
> -weak_alias (__ffs, ffsl)
> -#endif
> -
> -#else
> -#include <string/ffs.c>
> -#endif
> diff --git a/sysdeps/powerpc/math-use-builtins-ffs.h b/sysdeps/powerpc/math-use-builtins-ffs.h
> new file mode 100644
> index 0000000000..7b1d401823
> --- /dev/null
> +++ b/sysdeps/powerpc/math-use-builtins-ffs.h
> @@ -0,0 +1,6 @@
> +#define USE_FFS_BUILTIN    1
> +#ifdef __powerpc64__
> +# define USE_FFSLL_BUILTIN 1
> +#else
> +# define USE_FFSLL_BUILTIN 0
> +#endif
> diff --git a/sysdeps/powerpc/powerpc64/ffsll.c b/sysdeps/powerpc/powerpc64/ffsll.c
> deleted file mode 100644
> index d17cdd1c6b..0000000000
> --- a/sysdeps/powerpc/powerpc64/ffsll.c
> +++ /dev/null
> @@ -1,36 +0,0 @@
> -/* Find first set bit in a word, counted from least significant end.
> -   For PowerPC.
> -   Copyright (C) 1991-2023 Free Software Foundation, Inc.
> -   This file is part of the GNU C Library.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library; if not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -#define ffsl __something_else
> -#include <limits.h>
> -#include <string.h>
> -
> -#undef	ffs
> -
> -int
> -__ffsll (long long int x)
> -{
> -  int cnt;
> -
> -  asm ("cntlzd %0,%1" : "=r" (cnt) : "r" (x & -x));
> -  return 64 - cnt;
> -}
> -weak_alias (__ffsll, ffsll)
> -#undef ffsl
> -weak_alias (__ffsll, ffsl)
> diff --git a/sysdeps/s390/ffs.c b/sysdeps/s390/ffs.c
> deleted file mode 100644
> index 7627bd3346..0000000000
> --- a/sysdeps/s390/ffs.c
> +++ /dev/null
> @@ -1,69 +0,0 @@
> -/* ffs -- find first set bit in a word, counted from least significant end.
> -   S/390 version.
> -   Copyright (C) 2000-2023 Free Software Foundation, Inc.
> -   This file is part of the GNU C Library.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library; if not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -#include <limits.h>
> -#define ffsl __something_else
> -#include <string.h>
> -
> -#undef	ffs
> -
> -/* ffs: find first bit set. This is defined the same way as
> -   the libc and compiler builtin ffs routines, therefore
> -   differs in spirit from the above ffz (man ffs).  */
> -
> -int
> -__ffs (int x)
> -{
> -	int r;
> -
> -	if (x == 0)
> -	  return 0;
> -	__asm__("    lr	  %%r1,%1\n"
> -		"    sr	  %0,%0\n"
> -		"    tml  %%r1,0xFFFF\n"
> -		"    jnz  0f\n"
> -		"    ahi  %0,16\n"
> -		"    srl  %%r1,16\n"
> -		"0:  tml  %%r1,0x00FF\n"
> -		"    jnz  1f\n"
> -		"    ahi  %0,8\n"
> -		"    srl  %%r1,8\n"
> -		"1:  tml  %%r1,0x000F\n"
> -		"    jnz  2f\n"
> -		"    ahi  %0,4\n"
> -		"    srl  %%r1,4\n"
> -		"2:  tml  %%r1,0x0003\n"
> -		"    jnz  3f\n"
> -		"    ahi  %0,2\n"
> -		"    srl  %%r1,2\n"
> -		"3:  tml  %%r1,0x0001\n"
> -		"    jnz  4f\n"
> -		"    ahi  %0,1\n"
> -		"4:"
> -		: "=&d" (r) : "d" (x) : "cc", "1" );
> -	return r+1;
> -}
> -
> -weak_alias (__ffs, ffs)
> -libc_hidden_def (__ffs)
> -libc_hidden_builtin_def (ffs)
> -#if ULONG_MAX == UINT_MAX
> -#undef ffsl
> -weak_alias (__ffs, ffsl)
> -#endif
> diff --git a/sysdeps/x86_64/ffs.c b/sysdeps/x86_64/ffs.c
> deleted file mode 100644
> index a31202969e..0000000000
> --- a/sysdeps/x86_64/ffs.c
> +++ /dev/null
> @@ -1,38 +0,0 @@
> -/* ffs -- find first set bit in a word, counted from least significant end.
> -   For AMD x86-64.
> -   This file is part of the GNU C Library.
> -   Copyright (C) 1991-2023 Free Software Foundation, Inc.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library; if not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -#include <string.h>
> -
> -#undef	ffs
> -
> -int
> -__ffs (int x)
> -{
> -  int cnt;
> -  int tmp;
> -
> -  asm ("bsfl %2,%0\n"		/* Count low bits in X and store in %1.  */
> -       "cmovel %1,%0\n"		/* If number was zero, use -1 as result.  */
> -       : "=&r" (cnt), "=r" (tmp) : "rm" (x), "1" (-1));
> -
> -  return cnt + 1;
> -}
> -weak_alias (__ffs, ffs)
> -libc_hidden_def (__ffs)
> -libc_hidden_builtin_def (ffs)
> diff --git a/sysdeps/x86_64/ffsll.c b/sysdeps/x86_64/ffsll.c
> deleted file mode 100644
> index a1c13d4906..0000000000
> --- a/sysdeps/x86_64/ffsll.c
> +++ /dev/null
> @@ -1,41 +0,0 @@
> -/* ffsll -- find first set bit in a word, counted from least significant end.
> -   For AMD x86-64.
> -   This file is part of the GNU C Library.
> -   Copyright (C) 1991-2023 Free Software Foundation, Inc.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library; if not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -#define ffsl __something_else
> -#include <string.h>
> -
> -#undef	ffsll
> -
> -int
> -ffsll (long long int x)
> -{
> -  long long int cnt;
> -  long long int tmp;
> -
> -  asm ("bsfq %2,%0\n"		/* Count low bits in X and store in %1.  */
> -       "cmoveq %1,%0\n"		/* If number was zero, use -1 as result.  */
> -       : "=&r" (cnt), "=r" (tmp) : "rm" (x), "1" (-1));
> -
> -  return cnt + 1;
> -}
> -
> -#ifndef __ILP32__
> -#undef	ffsl
> -weak_alias (ffsll, ffsl)
> -#endif
> diff --git a/sysdeps/x86_64/math-use-builtins-ffs.h b/sysdeps/x86_64/math-use-builtins-ffs.h
> new file mode 100644
> index 0000000000..a83bb15414
> --- /dev/null
> +++ b/sysdeps/x86_64/math-use-builtins-ffs.h
> @@ -0,0 +1,2 @@
> +#define USE_FFS_BUILTIN   1
> +#define USE_FFSLL_BUILTIN 1
> diff --git a/sysdeps/x86_64/x32/ffs.c b/sysdeps/x86_64/x32/ffs.c
> deleted file mode 100644
> index fa7de8b887..0000000000
> --- a/sysdeps/x86_64/x32/ffs.c
> +++ /dev/null
> @@ -1,4 +0,0 @@
> -#define ffsl __something_else
> -#include <sysdeps/x86_64/ffs.c>
> -#undef ffsl
> -weak_alias (__ffs, ffsl)
diff mbox series

Patch

diff --git a/string/ffs.c b/string/ffs.c
index bf58f0b7ca..8302ae8420 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 0cc461a1cf..2315fe1bd7 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
diff --git a/sysdeps/aarch64/math-use-builtins-ffs.h b/sysdeps/aarch64/math-use-builtins-ffs.h
new file mode 100644
index 0000000000..a83bb15414
--- /dev/null
+++ b/sysdeps/aarch64/math-use-builtins-ffs.h
@@ -0,0 +1,2 @@ 
+#define USE_FFS_BUILTIN   1
+#define USE_FFSLL_BUILTIN 1
diff --git a/sysdeps/alpha/alphaev67/ffs.S b/sysdeps/alpha/alphaev67/ffs.S
deleted file mode 100644
index 48361bd8c5..0000000000
--- a/sysdeps/alpha/alphaev67/ffs.S
+++ /dev/null
@@ -1,51 +0,0 @@ 
-/* Copyright (C) 2000-2023 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library.  If not, see
-   <https://www.gnu.org/licenses/>.  */
-
-/* Finds the first bit set in an integer.  */
-
-#include <sysdep.h>
-
-	.arch ev6
-	.set noreorder
-	.set noat
-
-
-ENTRY(__ffs)
-#ifdef PROF
-	ldgp	gp, 0(pv)
-	lda	AT, _mcount
-	jsr	AT, (AT), _mcount
-	.prologue 1
-#else
-	.prologue 0
-#endif
-
-	zap	$16, 0xF0, $16
-	cttz	$16, $0
-	addq	$0, 1, $0
-	cmoveq	$16, 0, $0
-
-	nop
-	nop
-	nop
-	ret
-
-END(__ffs)
-
-weak_alias (__ffs, ffs)
-libc_hidden_def (__ffs)
-libc_hidden_builtin_def (ffs)
diff --git a/sysdeps/alpha/alphaev67/ffsll.S b/sysdeps/alpha/alphaev67/ffsll.S
deleted file mode 100644
index 52f406ec32..0000000000
--- a/sysdeps/alpha/alphaev67/ffsll.S
+++ /dev/null
@@ -1,44 +0,0 @@ 
-/* Copyright (C) 2000-2023 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library.  If not, see
-   <https://www.gnu.org/licenses/>.  */
-
-/* Finds the first bit set in a long.  */
-
-#include <sysdep.h>
-
-	.arch ev6
-	.set noreorder
-	.set noat
-
-ENTRY(ffsl)
-#ifdef PROF
-	ldgp	gp, 0(pv)
-	lda	AT, _mcount
-	jsr	AT, (AT), _mcount
-	.prologue 1
-#else
-	.prologue 0
-#endif
-
-	cttz	$16, $0
-	addq	$0, 1, $0
-	cmoveq	$16, 0, $0
-	ret
-
-END(ffsl)
-
-weak_extern (ffsl)
-weak_alias (ffsl, ffsll)
diff --git a/sysdeps/alpha/ffs.S b/sysdeps/alpha/ffs.S
deleted file mode 100644
index 047fd60352..0000000000
--- a/sysdeps/alpha/ffs.S
+++ /dev/null
@@ -1,90 +0,0 @@ 
-/* Copyright (C) 1996-2023 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library.  If not, see
-   <https://www.gnu.org/licenses/>.  */
-
-/* Finds the first bit set in an integer.  Optimized for the Alpha
-   architecture.  */
-
-#include <sysdep.h>
-
-	.set noreorder
-	.set noat
-
-
-ENTRY(__ffs)
-#ifdef PROF
-	ldgp	gp, 0(pv)
-	lda	AT, _mcount
-	jsr	AT, (AT), _mcount
-	.prologue 1
-	zap	$16, 0xF0, $16
-	br	$ffsl..ng
-#else
-	.prologue 0
-	zap	$16, 0xF0, $16
-	# FALLTHRU
-#endif
-END(__ffs)
-
-	.align 4
-ENTRY(ffsl)
-#ifdef PROF
-	ldgp	gp, 0(pv)
-	lda	AT, _mcount
-	jsr	AT, (AT), _mcount
-	.prologue 1
-$ffsl..ng:
-#else
-	.prologue 0
-#endif
-	not	$16, $1		# e0    :
-	ldi	$2, -1		# .. e1 :
-	cmpbge	$1, $2, $3	# e0    : bit N == 1 for byte N == 0
-	clr	$0		# .. e1 :
-	addq	$3, 1, $4	# e0    :
-	bic	$4, $3, $3	# e1    : bit N == 1 for first byte N != 0
-	and	$3, 0xF0, $4	# e0    :
-	and	$3, 0xCC, $5	# .. e1 :
-	and	$3, 0xAA, $6	# e0    :
-	cmovne	$4, 4, $0	# .. e1 :
-	cmovne	$5, 2, $5	# e0    :
-	cmovne  $6, 1, $6	# .. e1 :
-	addl	$0, $5, $0	# e0    :
-	addl	$0, $6, $0	# e1    : $0 == N
-	extbl	$16, $0, $1	# e0    : $1 == byte N
-	ldi	$2, 1		# .. e1 :
-	negq	$1, $3		# e0    :
-	and	$3, $1, $3	# e1    : bit N == least bit set of byte N
-	and	$3, 0xF0, $4	# e0    :
-	and	$3, 0xCC, $5	# .. e1 :
-	and	$3, 0xAA, $6	# e0    :
-	cmovne	$4, 5, $2	# .. e1 :
-	cmovne	$5, 2, $5	# e0    :
-	cmovne	$6, 1, $6	# .. e1 :
-	s8addl	$0, $2, $0	# e0    : mult byte ofs by 8 and sum
-	addl	$5, $6, $5	# .. e1 :
-	addl	$0, $5, $0	# e0    :
-	nop			# .. e1 :
-	cmoveq	$16, 0, $0	# e0    : trap input == 0 case.
-	ret			# .. e1 : 18
-
-END(ffsl)
-
-weak_alias (__ffs, ffs)
-libc_hidden_def (__ffs)
-libc_hidden_builtin_def (ffs)
-weak_extern (ffsl)
-weak_alias (ffsl, ffsll)
diff --git a/sysdeps/alpha/ffsll.S b/sysdeps/alpha/ffsll.S
deleted file mode 100644
index b2f46d899c..0000000000
--- a/sysdeps/alpha/ffsll.S
+++ /dev/null
@@ -1 +0,0 @@ 
-/* This function is defined in ffs.S.  */
diff --git a/sysdeps/alpha/math-use-builtins-ffs.h b/sysdeps/alpha/math-use-builtins-ffs.h
new file mode 100644
index 0000000000..9925e374ac
--- /dev/null
+++ b/sysdeps/alpha/math-use-builtins-ffs.h
@@ -0,0 +1,7 @@ 
+#ifdef __alpha_cix__
+# define USE_FFS_BUILTIN   1
+# define USE_FFSLL_BUILTIN 1
+#else
+# define USE_FFS_BUILTIN   0
+# define USE_FFSLL_BUILTIN 0
+#endif
diff --git a/sysdeps/arc/math-use-builtins-ffs.h b/sysdeps/arc/math-use-builtins-ffs.h
new file mode 100644
index 0000000000..c0f108c264
--- /dev/null
+++ b/sysdeps/arc/math-use-builtins-ffs.h
@@ -0,0 +1,2 @@ 
+#define USE_FFS_BUILTIN   1
+#define USE_FFSLL_BUILTIN 0
diff --git a/sysdeps/arm/armv6t2/ffs.S b/sysdeps/arm/armv6t2/ffs.S
deleted file mode 100644
index 870957a4bb..0000000000
--- a/sysdeps/arm/armv6t2/ffs.S
+++ /dev/null
@@ -1,36 +0,0 @@ 
-/* ffs -- find first set bit in an int, from least significant end.
-   Copyright (C) 2013-2023 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library.  If not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#include <sysdep.h>
-
-	.syntax unified
-	.text
-
-ENTRY (__ffs)
-	cmp	r0, #0
-	rbit	r0, r0
-	itt	ne
-	clzne	r0, r0
-	addne	r0, r0, #1
-	bx	lr
-END (__ffs)
-
-weak_alias (__ffs, ffs)
-weak_alias (__ffs, ffsl)
-libc_hidden_def (__ffs)
-libc_hidden_builtin_def (ffs)
diff --git a/sysdeps/arm/armv6t2/ffsll.S b/sysdeps/arm/armv6t2/ffsll.S
deleted file mode 100644
index bc3cbf81b0..0000000000
--- a/sysdeps/arm/armv6t2/ffsll.S
+++ /dev/null
@@ -1,50 +0,0 @@ 
-/* ffsll -- find first set bit in a long long, from least significant end.
-   Copyright (C) 2013-2023 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library.  If not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#include <sysdep.h>
-
-	.syntax unified
-	.text
-
-ENTRY (ffsll)
-	@ If low part is 0, operate on the high part.  Ensure that the
-	@ word on which we operate is in r0.  Set r2 to the bit offset
-	@ of the word being considered.  Set the flags for the word
-	@ being operated on.
-#ifdef __ARMEL__
-	cmp	r0, #0
-	itee	ne
-	movne	r2, #0
-	moveq	r2, #32
-	movseq	r0, r1
-#else
-	cmp	r1, #0
-	ittee	ne
-	movne	r2, #0
-	movne	r0, r1
-	moveq	r2, #32
-	cmpeq	r0, #0
-#endif
-	@ Perform the ffs on r0.
-	rbit	r0, r0
-	ittt	ne
-	clzne	r0, r0
-	addne	r2, r2, #1
-	addne	r0, r0, r2
-	bx	lr
-END (ffsll)
diff --git a/sysdeps/arm/armv6t2/math-use-builtins-ffs.h b/sysdeps/arm/armv6t2/math-use-builtins-ffs.h
new file mode 100644
index 0000000000..c0f108c264
--- /dev/null
+++ b/sysdeps/arm/armv6t2/math-use-builtins-ffs.h
@@ -0,0 +1,2 @@ 
+#define USE_FFS_BUILTIN   1
+#define USE_FFSLL_BUILTIN 0
diff --git a/sysdeps/generic/math-use-builtins-ffs.h b/sysdeps/generic/math-use-builtins-ffs.h
new file mode 100644
index 0000000000..add8537470
--- /dev/null
+++ b/sysdeps/generic/math-use-builtins-ffs.h
@@ -0,0 +1,2 @@ 
+#define USE_FFS_BUILTIN   0
+#define USE_FFSLL_BUILTIN 0
diff --git a/sysdeps/generic/math-use-builtins.h b/sysdeps/generic/math-use-builtins.h
index 04b1d0d5ab..038eb2c523 100644
--- a/sysdeps/generic/math-use-builtins.h
+++ b/sysdeps/generic/math-use-builtins.h
@@ -40,5 +40,6 @@ 
 #include <math-use-builtins-lrint.h>
 #include <math-use-builtins-llrint.h>
 #include <math-use-builtins-logb.h>
+#include <math-use-builtins-ffs.h>
 
 #endif /* MATH_USE_BUILTINS_H  */
diff --git a/sysdeps/i386/ffs.c b/sysdeps/i386/ffs.c
deleted file mode 100644
index b8e798420b..0000000000
--- a/sysdeps/i386/ffs.c
+++ /dev/null
@@ -1,49 +0,0 @@ 
-/* ffs -- find first set bit in a word, counted from least significant end.
-   For Intel 80x86, x>=3.
-   This file is part of the GNU C Library.
-   Copyright (C) 1991-2023 Free Software Foundation, Inc.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#define ffsl __something_else
-#include <string.h>
-
-#undef	ffs
-
-#ifdef	__GNUC__
-
-int
-__ffs (int x)
-{
-  int cnt;
-  int tmp;
-
-  asm ("xorl %0,%0\n"		/* Set CNT to zero.  */
-       "bsfl %2,%1\n"		/* Count low bits in X and store in %1.  */
-       "jz 1f\n"		/* Jump if OK, i.e. X was non-zero.  */
-       "leal 1(%1),%0\n"	/* Return bsfl-result plus one on %0.  */
-       "1:" : "=&a" (cnt), "=r" (tmp) : "rm" (x));
-
-  return cnt;
-}
-weak_alias (__ffs, ffs)
-libc_hidden_def (__ffs)
-libc_hidden_builtin_def (ffs)
-#undef ffsl
-weak_alias (__ffs, ffsl)
-
-#else
-#include <string/ffs.c>
-#endif
diff --git a/sysdeps/i386/i686/ffs.c b/sysdeps/i386/i686/ffs.c
deleted file mode 100644
index a522077cfe..0000000000
--- a/sysdeps/i386/i686/ffs.c
+++ /dev/null
@@ -1,47 +0,0 @@ 
-/* ffs -- find first set bit in a word, counted from least significant end.
-   For Intel 80x86, x>=6.
-   This file is part of the GNU C Library.
-   Copyright (C) 1991-2023 Free Software Foundation, Inc.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#define ffsl __something_else
-#include <string.h>
-
-#undef	ffs
-
-#ifdef	__GNUC__
-
-int
-__ffs (int x)
-{
-  int cnt;
-  int tmp;
-
-  asm ("bsfl %2,%0\n"		/* Count low bits in X and store in %1.  */
-       "cmovel %1,%0\n"		/* If number was zero, use -1 as result.  */
-       : "=&r" (cnt), "=r" (tmp) : "rm" (x), "1" (-1));
-
-  return cnt + 1;
-}
-weak_alias (__ffs, ffs)
-libc_hidden_def (__ffs)
-libc_hidden_builtin_def (ffs)
-#undef ffsl
-weak_alias (__ffs, ffsl)
-
-#else
-#include <string/ffs.c>
-#endif
diff --git a/sysdeps/i386/math-use-builtins-ffs.h b/sysdeps/i386/math-use-builtins-ffs.h
new file mode 100644
index 0000000000..c0f108c264
--- /dev/null
+++ b/sysdeps/i386/math-use-builtins-ffs.h
@@ -0,0 +1,2 @@ 
+#define USE_FFS_BUILTIN   1
+#define USE_FFSLL_BUILTIN 0
diff --git a/sysdeps/ia64/math-use-builtins-ffs.h b/sysdeps/ia64/math-use-builtins-ffs.h
new file mode 100644
index 0000000000..a83bb15414
--- /dev/null
+++ b/sysdeps/ia64/math-use-builtins-ffs.h
@@ -0,0 +1,2 @@ 
+#define USE_FFS_BUILTIN   1
+#define USE_FFSLL_BUILTIN 1
diff --git a/sysdeps/m68k/ffs.c b/sysdeps/m68k/ffs.c
deleted file mode 100644
index 4415bb0cff..0000000000
--- a/sysdeps/m68k/ffs.c
+++ /dev/null
@@ -1,46 +0,0 @@ 
-/* ffs -- find first set bit in a word, counted from least significant end.
-   For mc68020, mc68030, mc68040.
-   This file is part of the GNU C Library.
-   Copyright (C) 1991-2023 Free Software Foundation, Inc.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library.  If not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#define ffsl __something_else
-#include <string.h>
-
-#undef	ffs
-
-#if	defined (__GNUC__) && defined (__mc68020__)
-
-int
-__ffs (int x)
-{
-  int cnt;
-
-  asm ("bfffo %1{#0:#0},%0" : "=d" (cnt) : "dm" (x & -x));
-
-  return 32 - cnt;
-}
-weak_alias (__ffs, ffs)
-libc_hidden_def (__ffs)
-libc_hidden_builtin_def (ffs)
-#undef ffsl
-weak_alias (__ffs, ffsl)
-
-#else
-
-#include <string/ffs.c>
-
-#endif
diff --git a/sysdeps/m68k/math-use-builtins-ffs.h b/sysdeps/m68k/math-use-builtins-ffs.h
new file mode 100644
index 0000000000..4e1d994453
--- /dev/null
+++ b/sysdeps/m68k/math-use-builtins-ffs.h
@@ -0,0 +1,7 @@ 
+#if defined __mc68020__ || defined __mc68030__ || defined __mc68040__ \
+    || defined __mc68060__
+# define USE_FFS_BUILTIN  1
+#else
+# define USE_FFS_BUILTIN  0
+#endif
+#define USE_FFSLL_BUILTIN 0
diff --git a/sysdeps/powerpc/ffs.c b/sysdeps/powerpc/ffs.c
deleted file mode 100644
index 0a046dab99..0000000000
--- a/sysdeps/powerpc/ffs.c
+++ /dev/null
@@ -1,46 +0,0 @@ 
-/* Find first set bit in a word, counted from least significant end.
-   For PowerPC.
-   Copyright (C) 1991-2023 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#define ffsl __something_else
-#include <limits.h>
-#include <string.h>
-
-#undef	ffs
-
-#ifdef 	__GNUC__
-
-int
-__ffs (int x)
-{
-  int cnt;
-
-  asm ("cntlzw %0,%1" : "=r" (cnt) : "r" (x & -x));
-  return 32 - cnt;
-}
-weak_alias (__ffs, ffs)
-libc_hidden_def (__ffs)
-libc_hidden_builtin_def (ffs)
-#if ULONG_MAX == UINT_MAX
-#undef ffsl
-weak_alias (__ffs, ffsl)
-#endif
-
-#else
-#include <string/ffs.c>
-#endif
diff --git a/sysdeps/powerpc/math-use-builtins-ffs.h b/sysdeps/powerpc/math-use-builtins-ffs.h
new file mode 100644
index 0000000000..7b1d401823
--- /dev/null
+++ b/sysdeps/powerpc/math-use-builtins-ffs.h
@@ -0,0 +1,6 @@ 
+#define USE_FFS_BUILTIN    1
+#ifdef __powerpc64__
+# define USE_FFSLL_BUILTIN 1
+#else
+# define USE_FFSLL_BUILTIN 0
+#endif
diff --git a/sysdeps/powerpc/powerpc64/ffsll.c b/sysdeps/powerpc/powerpc64/ffsll.c
deleted file mode 100644
index d17cdd1c6b..0000000000
--- a/sysdeps/powerpc/powerpc64/ffsll.c
+++ /dev/null
@@ -1,36 +0,0 @@ 
-/* Find first set bit in a word, counted from least significant end.
-   For PowerPC.
-   Copyright (C) 1991-2023 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#define ffsl __something_else
-#include <limits.h>
-#include <string.h>
-
-#undef	ffs
-
-int
-__ffsll (long long int x)
-{
-  int cnt;
-
-  asm ("cntlzd %0,%1" : "=r" (cnt) : "r" (x & -x));
-  return 64 - cnt;
-}
-weak_alias (__ffsll, ffsll)
-#undef ffsl
-weak_alias (__ffsll, ffsl)
diff --git a/sysdeps/s390/ffs.c b/sysdeps/s390/ffs.c
deleted file mode 100644
index 7627bd3346..0000000000
--- a/sysdeps/s390/ffs.c
+++ /dev/null
@@ -1,69 +0,0 @@ 
-/* ffs -- find first set bit in a word, counted from least significant end.
-   S/390 version.
-   Copyright (C) 2000-2023 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#include <limits.h>
-#define ffsl __something_else
-#include <string.h>
-
-#undef	ffs
-
-/* ffs: find first bit set. This is defined the same way as
-   the libc and compiler builtin ffs routines, therefore
-   differs in spirit from the above ffz (man ffs).  */
-
-int
-__ffs (int x)
-{
-	int r;
-
-	if (x == 0)
-	  return 0;
-	__asm__("    lr	  %%r1,%1\n"
-		"    sr	  %0,%0\n"
-		"    tml  %%r1,0xFFFF\n"
-		"    jnz  0f\n"
-		"    ahi  %0,16\n"
-		"    srl  %%r1,16\n"
-		"0:  tml  %%r1,0x00FF\n"
-		"    jnz  1f\n"
-		"    ahi  %0,8\n"
-		"    srl  %%r1,8\n"
-		"1:  tml  %%r1,0x000F\n"
-		"    jnz  2f\n"
-		"    ahi  %0,4\n"
-		"    srl  %%r1,4\n"
-		"2:  tml  %%r1,0x0003\n"
-		"    jnz  3f\n"
-		"    ahi  %0,2\n"
-		"    srl  %%r1,2\n"
-		"3:  tml  %%r1,0x0001\n"
-		"    jnz  4f\n"
-		"    ahi  %0,1\n"
-		"4:"
-		: "=&d" (r) : "d" (x) : "cc", "1" );
-	return r+1;
-}
-
-weak_alias (__ffs, ffs)
-libc_hidden_def (__ffs)
-libc_hidden_builtin_def (ffs)
-#if ULONG_MAX == UINT_MAX
-#undef ffsl
-weak_alias (__ffs, ffsl)
-#endif
diff --git a/sysdeps/x86_64/ffs.c b/sysdeps/x86_64/ffs.c
deleted file mode 100644
index a31202969e..0000000000
--- a/sysdeps/x86_64/ffs.c
+++ /dev/null
@@ -1,38 +0,0 @@ 
-/* ffs -- find first set bit in a word, counted from least significant end.
-   For AMD x86-64.
-   This file is part of the GNU C Library.
-   Copyright (C) 1991-2023 Free Software Foundation, Inc.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#include <string.h>
-
-#undef	ffs
-
-int
-__ffs (int x)
-{
-  int cnt;
-  int tmp;
-
-  asm ("bsfl %2,%0\n"		/* Count low bits in X and store in %1.  */
-       "cmovel %1,%0\n"		/* If number was zero, use -1 as result.  */
-       : "=&r" (cnt), "=r" (tmp) : "rm" (x), "1" (-1));
-
-  return cnt + 1;
-}
-weak_alias (__ffs, ffs)
-libc_hidden_def (__ffs)
-libc_hidden_builtin_def (ffs)
diff --git a/sysdeps/x86_64/ffsll.c b/sysdeps/x86_64/ffsll.c
deleted file mode 100644
index a1c13d4906..0000000000
--- a/sysdeps/x86_64/ffsll.c
+++ /dev/null
@@ -1,41 +0,0 @@ 
-/* ffsll -- find first set bit in a word, counted from least significant end.
-   For AMD x86-64.
-   This file is part of the GNU C Library.
-   Copyright (C) 1991-2023 Free Software Foundation, Inc.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#define ffsl __something_else
-#include <string.h>
-
-#undef	ffsll
-
-int
-ffsll (long long int x)
-{
-  long long int cnt;
-  long long int tmp;
-
-  asm ("bsfq %2,%0\n"		/* Count low bits in X and store in %1.  */
-       "cmoveq %1,%0\n"		/* If number was zero, use -1 as result.  */
-       : "=&r" (cnt), "=r" (tmp) : "rm" (x), "1" (-1));
-
-  return cnt + 1;
-}
-
-#ifndef __ILP32__
-#undef	ffsl
-weak_alias (ffsll, ffsl)
-#endif
diff --git a/sysdeps/x86_64/math-use-builtins-ffs.h b/sysdeps/x86_64/math-use-builtins-ffs.h
new file mode 100644
index 0000000000..a83bb15414
--- /dev/null
+++ b/sysdeps/x86_64/math-use-builtins-ffs.h
@@ -0,0 +1,2 @@ 
+#define USE_FFS_BUILTIN   1
+#define USE_FFSLL_BUILTIN 1
diff --git a/sysdeps/x86_64/x32/ffs.c b/sysdeps/x86_64/x32/ffs.c
deleted file mode 100644
index fa7de8b887..0000000000
--- a/sysdeps/x86_64/x32/ffs.c
+++ /dev/null
@@ -1,4 +0,0 @@ 
-#define ffsl __something_else
-#include <sysdeps/x86_64/ffs.c>
-#undef ffsl
-weak_alias (__ffs, ffsl)