Remove atomic-machine headers

  Remove the last few unnecessary defines from all the atomic-machine headers so almost
all can be removed. Set __HAVE_64B_ATOMICS as part of configure - this is not only
simpler but also more correct since it depends on the compiler and settings. Note that
__atomic_always_lock_free is quite buggy, but the expression used works correctly,
including on LLVM. Remove the odd ATOMIC_EXCHANGE_USES_CAS as it is only used once and
set incorrectly by many targets.

Passes regress on AArch64 and buildmanyglibc.

---
  

* Wilco Dijkstra via Libc-alpha:

> diff --git a/configure b/configure
> index ff2c406b3b573484c843742d292fc2e0ee0e3008..3efdf45f99af71a482509f559d9de90aa294700c 100755
> --- a/configure
> +++ b/configure
> @@ -727,6 +727,7 @@ infodir
>  docdir
>  oldincludedir
>  includedir
> +runstatedir
>  localstatedir
>  sharedstatedir
>  sysconfdir

Spurious difference.

> +typedef struct { long long t; } X;
> +extern void has_64b_atomics(void);
> +void f(void)
> +{
> +  X x;
> +  /* Use address of structure with 64-bit type.  This avoids incorrect
> +     implementations which return true even if long long is not 64-bit aligned.
> +     This works on GCC and LLVM - other cases have bugs and they disagree.  */
> +  if (__atomic_always_lock_free (sizeof (x), &x))
> +    has_64b_atomics();

Can you use _static_assert, given that it's supposed to yield a
compile-time constant?

I'd be suprised if __atomic_always_lock_free is correct on all
glibc-supported architectures, though.

> diff --git a/sysdeps/x86/atomic-machine.h b/sysdeps/x86/atomic-machine.h
> index 98541a2d06ff5e4aa8c789ab7405215097471971..303458d1296e4b1cd7cd654e0904ace0ffc52fae 100644
> --- a/sysdeps/x86/atomic-machine.h
> +++ b/sysdeps/x86/atomic-machine.h
> @@ -21,17 +21,6 @@
>  
>  #include <tls.h>			/* For mach.  */
>  
> -#ifdef __x86_64__
> -# define __HAVE_64B_ATOMICS		1
> -#else
> -/* Since the Pentium, i386 CPUs have supported 64-bit atomics, but the
> -   i386 psABI supplement provides only 4-byte alignment for uint64_t
> -   inside structs, so it is currently not possible to use 64-bit
> -   atomics on this platform.  */
> -# define __HAVE_64B_ATOMICS		0
> -#endif
> -#define ATOMIC_EXCHANGE_USES_CAS	0
> -
>  #define atomic_spin_nop() __asm ("pause")
>  
>  #endif /* atomic-machine.h */

Please preserve this comment somewhere.  Maybe folod it into the
configure test example.

Thanks,
Florian
  

Hi Florian,

>> +runstatedir
>
> Spurious difference.

I've removed it from v2, but it reappears whenever I run autoconf...

> Can you use _static_assert, given that it's supposed to yield a
> compile-time constant?

Yes that works fine. I've also used that in include/atomic.h so you get better
error messages if it does fail.

> I'd be suprised if __atomic_always_lock_free is correct on all
> glibc-supported architectures, though.

It passes build-many-glibcs, so it works well enough. I double-checked the
config output, and it is as expected: 64-bit targets say yes, 32-bit targets say no
except for armv7-a (which is correct).

> -/* Since the Pentium, i386 CPUs have supported 64-bit atomics, but the
> -   i386 psABI supplement provides only 4-byte alignment for uint64_t
> -   inside structs, so it is currently not possible to use 64-bit
> -   atomics on this platform.  */

> Please preserve this comment somewhere.  Maybe folod it into the
> configure test example.

This comment is in the configure test:

> +  /* Use address of structure with 64-bit type.  This avoids incorrect
> +     implementations which return true even if long long is not 64-bit aligned.
> +     This works on GCC and LLVM - other cases have bugs and they disagree.  */

This is more generic since unaligned 64-bit types are common on many 32-bit targets.

Cheers,
Wilco

v2: Add llongarch, fix leon3, use _Static_assert

Remove the last few unnecessary defines from all the atomic-machine headers so almost
all can be removed. Set __HAVE_64B_ATOMICS as part of configure - this is not only
simpler but also more correct since it depends on the compiler and settings. Note that
__atomic_always_lock_free is quite buggy, but the expression used works correctly,
including on LLVM. Remove the odd ATOMIC_EXCHANGE_USES_CAS as it is only used once and
set incorrectly by many targets.

Passes regress on AArch64 and buildmanyglibc.

---
diff --git a/config.h.in b/config.h.in
index 43d32518ab34c048d51f2586ed1762c95d14ef68..a7607a3ddfaedd014c8890100ef76795888a10be 100644
--- a/config.h.in
+++ b/config.h.in
@@ -292,4 +292,7 @@
 /* Define if -mmovbe is enabled by default on x86.  */
 #undef HAVE_X86_MOVBE
 
+/* Set to 1 if 64 bit atomics are supported.  */
+#define __HAVE_64B_ATOMICS 0
+
 #endif
diff --git a/configure b/configure
index ff2c406b3b573484c843742d292fc2e0ee0e3008..fdbc9a6c2e6b84ff60e833eaf2719310444a5dac 100755
--- a/configure
+++ b/configure
@@ -6316,6 +6316,43 @@ if test "$libc_cv_gcc_builtin_memset" = yes ; then
 
 fi
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for 64-bit atomic support" >&5
+$as_echo_n "checking for 64-bit atomic support... " >&6; }
+if ${libc_cv_gcc_has_64b_atomics+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat > conftest.c <<\EOF
+typedef struct { long long t; } X;
+extern void has_64b_atomics(void);
+void f(void)
+{
+  X x;
+  /* Use address of structure with 64-bit type.  This avoids incorrect
+     implementations which return true even if long long is not 64-bit aligned.
+     This works on GCC and LLVM - other cases have bugs and they disagree.  */
+  _Static_assert (__atomic_always_lock_free (sizeof (x), &x), "no_64b_atomics");
+}
+EOF
+if { ac_try='${CC-cc} -O2 -S conftest.c'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; };
+then
+  libc_cv_gcc_has_64b_atomics=yes
+else
+  libc_cv_gcc_has_64b_atomics=no
+fi
+rm -f conftest*
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_has_64b_atomics" >&5
+$as_echo "$libc_cv_gcc_has_64b_atomics" >&6; }
+if test "$libc_cv_gcc_has_64b_atomics" = yes; then
+  $as_echo "#define __HAVE_64B_ATOMICS 1" >>confdefs.h
+
+fi
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for redirection of built-in functions" >&5
 $as_echo_n "checking for redirection of built-in functions... " >&6; }
 if ${libc_cv_gcc_builtin_redirection+:} false; then :
diff --git a/configure.ac b/configure.ac
index eb5bc6a1313acb3f3614645739adeb7638f19617..ab1a248f50e7a4c0e36f8af6e2d6f7d8bf4c1787 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1443,6 +1443,31 @@ if test "$libc_cv_gcc_builtin_memset" = yes ; then
   AC_DEFINE(HAVE_BUILTIN_MEMSET)
 fi
 
+AC_CACHE_CHECK(for 64-bit atomic support, libc_cv_gcc_has_64b_atomics, [dnl
+cat > conftest.c <<\EOF
+typedef struct { long long t; } X;
+extern void has_64b_atomics(void);
+void f(void)
+{
+  X x;
+  /* Use address of structure with 64-bit type.  This avoids incorrect
+     implementations which return true even if long long is not 64-bit aligned.
+     This works on GCC and LLVM - other cases have bugs and they disagree.  */
+  _Static_assert (__atomic_always_lock_free (sizeof (x), &x), "no_64b_atomics");
+}
+EOF
+dnl
+if AC_TRY_COMMAND([${CC-cc} -O2 -S conftest.c]);
+then
+  libc_cv_gcc_has_64b_atomics=yes
+else
+  libc_cv_gcc_has_64b_atomics=no
+fi
+rm -f conftest* ])
+if test "$libc_cv_gcc_has_64b_atomics" = yes; then
+  AC_DEFINE(__HAVE_64B_ATOMICS, 1)
+fi
+
 AC_CACHE_CHECK(for redirection of built-in functions, libc_cv_gcc_builtin_redirection, [dnl
 cat > conftest.c <<\EOF
 extern char *strstr (const char *, const char *) __asm ("my_strstr");
diff --git a/include/atomic.h b/include/atomic.h
index e9ec063228b5aeeccb4c5d14d7c894f00617eefb..4494650f03d20299dcf0d6ee314e93ed7fcf7043 100644
--- a/include/atomic.h
+++ b/include/atomic.h
@@ -27,11 +27,6 @@
    - support functions like barriers.  They also have the prefix
      "atomic_".
 
-   Architectures must provide a few lowlevel macros (the compare
-   and exchange definitions).  All others are optional.  They
-   should only be provided if the architecture has specific
-   support for the operation.
-
    As <atomic.h> macros are usually heavily nested and often use local
    variables to make sure side-effects are evaluated properly, use for
    macro local variables a per-macro unique prefix.  This file uses
@@ -74,43 +69,17 @@
      __atg11_oldval; })
 #endif
 
-
-/* This is equal to 1 iff the architecture supports 64b atomic operations.  */
-#ifndef __HAVE_64B_ATOMICS
-#error Unable to determine if 64-bit atomics are present.
-#endif
-
 /* The following functions are a subset of the atomic operations provided by
    C11.  Usually, a function named atomic_OP_MO(args) is equivalent to C11's
    atomic_OP_explicit(args, memory_order_MO); exceptions noted below.  */
 
-
-/* We require 32b atomic operations; some archs also support 64b atomic
-   operations.  */
-void __atomic_link_error (void);
-# if __HAVE_64B_ATOMICS == 1
-#  define __atomic_check_size(mem) \
-   if ((sizeof (*mem) != 4) && (sizeof (*mem) != 8))			      \
-     __atomic_link_error ();
-# else
-#  define __atomic_check_size(mem) \
-   if (sizeof (*mem) != 4)						      \
-     __atomic_link_error ();
-# endif
-/* We additionally provide 8b and 16b atomic loads and stores; we do not yet
-   need other atomic operations of such sizes, and restricting the support to
-   loads and stores makes this easier for archs that do not have native
-   support for atomic operations to less-than-word-sized data.  */
-# if __HAVE_64B_ATOMICS == 1
-#  define __atomic_check_size_ls(mem) \
-   if ((sizeof (*mem) != 1) && (sizeof (*mem) != 2) && (sizeof (*mem) != 4)   \
-       && (sizeof (*mem) != 8))						      \
-     __atomic_link_error ();
-# else
-#  define __atomic_check_size_ls(mem) \
-   if ((sizeof (*mem) != 1) && (sizeof (*mem) != 2) && sizeof (*mem) != 4)    \
-     __atomic_link_error ();
-# endif
+/* Check atomic operations are lock free.  Since this doesn't work correctly
+   on all targets (eg. if uint64_t is 4-byte aligned), use__HAVE_64B_ATOMICS
+   for 64-bit types.  */
+#define __atomic_check_size(mem) \
+  _Static_assert (__atomic_always_lock_free (sizeof (*(mem)), 0) &&	      \
+		  !(sizeof (*(mem)) == 8 && __HAVE_64B_ATOMICS == 0),	      \
+		  "atomic not lock free!")
 
 # define atomic_thread_fence_acquire() \
   __atomic_thread_fence (__ATOMIC_ACQUIRE)
@@ -120,20 +89,20 @@ void __atomic_link_error (void);
   __atomic_thread_fence (__ATOMIC_SEQ_CST)
 
 # define atomic_load_relaxed(mem) \
-  ({ __atomic_check_size_ls((mem));					      \
+  ({ __atomic_check_size ((mem));					      \
      __atomic_load_n ((mem), __ATOMIC_RELAXED); })
 # define atomic_load_acquire(mem) \
-  ({ __atomic_check_size_ls((mem));					      \
+  ({ __atomic_check_size ((mem));					      \
      __atomic_load_n ((mem), __ATOMIC_ACQUIRE); })
 
 # define atomic_store_relaxed(mem, val) \
   do {									      \
-    __atomic_check_size_ls((mem));					      \
+    __atomic_check_size ((mem));					      \
     __atomic_store_n ((mem), (val), __ATOMIC_RELAXED);			      \
   } while (0)
 # define atomic_store_release(mem, val) \
   do {									      \
-    __atomic_check_size_ls((mem));					      \
+    __atomic_check_size ((mem));					      \
     __atomic_store_n ((mem), (val), __ATOMIC_RELEASE);			      \
   } while (0)
 
@@ -218,12 +187,4 @@ void __atomic_link_error (void);
 # define atomic_spin_nop() do { /* nothing */ } while (0)
 #endif
 
-/* ATOMIC_EXCHANGE_USES_CAS is non-zero if atomic_exchange operations
-   are implemented based on a CAS loop; otherwise, this is zero and we assume
-   that the atomic_exchange operations could provide better performance
-   than a CAS loop.  */
-#ifndef ATOMIC_EXCHANGE_USES_CAS
-# error ATOMIC_EXCHANGE_USES_CAS has to be defined.
-#endif
-
 #endif	/* atomic.h */
diff --git a/nptl/pthread_spin_lock.c b/nptl/pthread_spin_lock.c
index 19d1759f9aa350d5a711ac8abe6f9db1464a1012..9122a260303a4356d7ee68274f04b542090de380 100644
--- a/nptl/pthread_spin_lock.c
+++ b/nptl/pthread_spin_lock.c
@@ -26,29 +26,12 @@ __pthread_spin_lock (pthread_spinlock_t *lock)
   int val = 0;
 
   /* We assume that the first try mostly will be successful, thus we use
-     atomic_exchange if it is not implemented by a CAS loop (we also assume
-     that atomic_exchange can be faster if it succeeds, see
-     ATOMIC_EXCHANGE_USES_CAS).  Otherwise, we use a weak CAS and not an
-     exchange so we bail out after the first failed attempt to change the
-     state.  For the subsequent attempts we use atomic_compare_and_exchange
-     after we observe that the lock is not acquired.
-     See also comment in pthread_spin_trylock.
+     atomic_exchange.
      We use acquire MO to synchronize-with the release MO store in
      pthread_spin_unlock, and thus ensure that prior critical sections
      happen-before this critical section.  */
-#if ! ATOMIC_EXCHANGE_USES_CAS
-  /* Try to acquire the lock with an exchange instruction as this architecture
-     has such an instruction and we assume it is faster than a CAS.
-     The acquisition succeeds if the lock is not in an acquired state.  */
   if (__glibc_likely (atomic_exchange_acquire (lock, 1) == 0))
     return 0;
-#else
-  /* Try to acquire the lock with a CAS instruction as this architecture
-     has no exchange instruction.  The acquisition succeeds if the lock is not
-     acquired.  */
-  if (__glibc_likely (atomic_compare_exchange_weak_acquire (lock, &val, 1)))
-    return 0;
-#endif
 
   do
     {
diff --git a/nptl/pthread_spin_trylock.c b/nptl/pthread_spin_trylock.c
index f2b12f9b4fe34340c9a2e449f2652908a7ff469d..3bd870401cdb336fe05469c3944b82fa563869be 100644
--- a/nptl/pthread_spin_trylock.c
+++ b/nptl/pthread_spin_trylock.c
@@ -24,57 +24,8 @@
 int
 __pthread_spin_trylock (pthread_spinlock_t *lock)
 {
-  /* For the spin try lock, we have the following possibilities:
-
-     1) If we assume that trylock will most likely succeed in practice:
-     * We just do an exchange.
-
-     2) If we want to bias towards cases where trylock succeeds, but don't
-     rule out contention:
-     * If exchange is not implemented by a CAS loop, and exchange is faster
-     than CAS, do an exchange.
-     * If exchange is implemented by a CAS loop, use a weak CAS and not an
-     exchange so we bail out after the first failed attempt to change the state.
-
-     3) If we expect contention to be likely:
-     * If CAS always brings the cache line into an exclusive state even if the
-     spinlock is already acquired, then load the value first with
-     atomic_load_relaxed and test if lock is not acquired. Then do 2).
-
-     We assume that 2) is the common case, and that this won't be slower than
-     1) in the common case.
-
-     We use acquire MO to synchronize-with the release MO store in
-     pthread_spin_unlock, and thus ensure that prior critical sections
-     happen-before this critical section.  */
-#if ! ATOMIC_EXCHANGE_USES_CAS
-  /* Try to acquire the lock with an exchange instruction as this architecture
-     has such an instruction and we assume it is faster than a CAS.
-     The acquisition succeeds if the lock is not in an acquired state.  */
   if (atomic_exchange_acquire (lock, 1) == 0)
     return 0;
-#else
-  /* Try to acquire the lock with a CAS instruction as this architecture
-     has no exchange instruction.  The acquisition succeeds if the lock is not
-     acquired.  */
-  do
-    {
-      int val = 0;
-      if (atomic_compare_exchange_weak_acquire (lock, &val, 1))
-	return 0;
-    }
-  /* atomic_compare_exchange_weak_acquire can fail spuriously.  Whereas
-     C++11 and C11 make it clear that trylock operations can fail spuriously,
-     POSIX does not explicitly specify this; it only specifies that failing
-     synchronization operations do not need to have synchronization effects
-     themselves, but a spurious failure is something that could contradict a
-     happens-before established earlier (e.g., that we need to observe that
-     the lock is acquired).  Therefore, we emulate a strong CAS by simply
-     checking with a relaxed MO load that the lock is really acquired before
-     returning EBUSY; the additional overhead this may cause is on the slow
-     path.  */
-  while (atomic_load_relaxed (lock) == 0);
-#endif
 
   return EBUSY;
 }
diff --git a/sysdeps/aarch64/atomic-machine.h b/sysdeps/aarch64/atomic-machine.h
deleted file mode 100644
index 2dc1c524e40e2e805161e6d9b1b385b85c53a5c8..0000000000000000000000000000000000000000
--- a/sysdeps/aarch64/atomic-machine.h
+++ /dev/null
@@ -1,25 +0,0 @@
-/* Copyright (C) 2003-2022 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/>.  */
-
-#ifndef _AARCH64_ATOMIC_MACHINE_H
-#define _AARCH64_ATOMIC_MACHINE_H	1
-
-#define __HAVE_64B_ATOMICS 1
-#define ATOMIC_EXCHANGE_USES_CAS 0
-
-#endif
diff --git a/sysdeps/alpha/atomic-machine.h b/sysdeps/alpha/atomic-machine.h
deleted file mode 100644
index 7fbe5b87eebf323d38fe1349b02aa56fe199cab3..0000000000000000000000000000000000000000
--- a/sysdeps/alpha/atomic-machine.h
+++ /dev/null
@@ -1,23 +0,0 @@
-/* Copyright (C) 2003-2022 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 <stdint.h>
-
-#define __HAVE_64B_ATOMICS 1
-
-/* XXX Is this actually correct?  */
-#define ATOMIC_EXCHANGE_USES_CAS 1
diff --git a/sysdeps/arc/atomic-machine.h b/sysdeps/arc/atomic-machine.h
deleted file mode 100644
index 2d519e3bbfa9ce77f4a41e313b67a690569d032e..0000000000000000000000000000000000000000
--- a/sysdeps/arc/atomic-machine.h
+++ /dev/null
@@ -1,28 +0,0 @@
-/* Low-level functions for atomic operations. ARC version.
-   Copyright (C) 2020-2022 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/>.  */
-
-#ifndef _ARC_BITS_ATOMIC_H
-#define _ARC_BITS_ATOMIC_H 1
-
-#define __HAVE_64B_ATOMICS 0
-
-/* ARC does have legacy atomic EX reg, [mem] instruction but the micro-arch
-   is not as optimal as LLOCK/SCOND specially for SMP.  */
-#define ATOMIC_EXCHANGE_USES_CAS 1
-
-#endif /* _ARC_BITS_ATOMIC_H */
diff --git a/sysdeps/arm/atomic-machine.h b/sysdeps/arm/atomic-machine.h
deleted file mode 100644
index b172573ae74dc9d6c7618bfdb76f5fb0429469f8..0000000000000000000000000000000000000000
--- a/sysdeps/arm/atomic-machine.h
+++ /dev/null
@@ -1,20 +0,0 @@
-/* Atomic operations.  Pure ARM version.
-   Copyright (C) 2002-2022 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 __HAVE_64B_ATOMICS 0
-#define ATOMIC_EXCHANGE_USES_CAS 1
diff --git a/sysdeps/csky/atomic-machine.h b/sysdeps/csky/atomic-machine.h
deleted file mode 100644
index 4a7dc63be2044990852c52500943c90c898363be..0000000000000000000000000000000000000000
--- a/sysdeps/csky/atomic-machine.h
+++ /dev/null
@@ -1,25 +0,0 @@
-/* Atomic operations.  C-SKY version.
-   Copyright (C) 2018-2022 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/>.  */
-
-#ifndef __CSKY_ATOMIC_H_
-#define __CSKY_ATOMIC_H_
-
-#define __HAVE_64B_ATOMICS 0
-#define ATOMIC_EXCHANGE_USES_CAS 1
-
-#endif /* atomic-machine.h */
diff --git a/sysdeps/ia64/atomic-machine.h b/sysdeps/ia64/atomic-machine.h
deleted file mode 100644
index 6f31c7b2eea67b5d8766dea1c38df6eedc168ebf..0000000000000000000000000000000000000000
--- a/sysdeps/ia64/atomic-machine.h
+++ /dev/null
@@ -1,23 +0,0 @@
-/* Copyright (C) 2003-2022 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 <ia64intrin.h>
-
-#define __HAVE_64B_ATOMICS 1
-
-/* XXX Is this actually correct?  */
-#define ATOMIC_EXCHANGE_USES_CAS 0
diff --git a/sysdeps/m68k/coldfire/atomic-machine.h b/sysdeps/m68k/coldfire/atomic-machine.h
deleted file mode 100644
index 1503703ed36b825f6e9f2cb2ed1516cd80bd9947..0000000000000000000000000000000000000000
--- a/sysdeps/m68k/coldfire/atomic-machine.h
+++ /dev/null
@@ -1,27 +0,0 @@
-/* Copyright (C) 2003-2022 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/>.  */
-
-#ifndef _ATOMIC_MACHINE_H
-#define _ATOMIC_MACHINE_H	1
-
-/* If we have just non-atomic operations, we can as well make them wide.  */
-#define __HAVE_64B_ATOMICS 1
-
-/* XXX Is this actually correct?  */
-#define ATOMIC_EXCHANGE_USES_CAS 1
-
-#endif
diff --git a/sysdeps/m68k/m680x0/m68020/atomic-machine.h b/sysdeps/m68k/m680x0/m68020/atomic-machine.h
deleted file mode 100644
index d356b55c9f9082db8dde734c254e01a631201206..0000000000000000000000000000000000000000
--- a/sysdeps/m68k/m680x0/m68020/atomic-machine.h
+++ /dev/null
@@ -1,22 +0,0 @@
-/* Copyright (C) 2003-2022 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/>.  */
-
-/* GCC does not support lock-free 64-bit atomic_load/store.  */
-#define __HAVE_64B_ATOMICS 0
-
-/* XXX Is this actually correct?  */
-#define ATOMIC_EXCHANGE_USES_CAS 1
diff --git a/sysdeps/microblaze/atomic-machine.h b/sysdeps/microblaze/atomic-machine.h
deleted file mode 100644
index 4e7ccce21e59453f5233bdf82b22215d9a6d17b3..0000000000000000000000000000000000000000
--- a/sysdeps/microblaze/atomic-machine.h
+++ /dev/null
@@ -1,24 +0,0 @@
-/* Copyright (C) 2003-2022 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>
-
-#define __HAVE_64B_ATOMICS 0
-
-/* XXX Is this actually correct?  */
-#define ATOMIC_EXCHANGE_USES_CAS 1
diff --git a/sysdeps/mips/atomic-machine.h b/sysdeps/mips/atomic-machine.h
deleted file mode 100644
index 1e611c2153996d28e14611c60189f52d0919b79c..0000000000000000000000000000000000000000
--- a/sysdeps/mips/atomic-machine.h
+++ /dev/null
@@ -1,38 +0,0 @@
-/* Low-level functions for atomic operations. Mips version.
-   Copyright (C) 2005-2022 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/>.  */
-
-#ifndef _MIPS_ATOMIC_MACHINE_H
-#define _MIPS_ATOMIC_MACHINE_H 1
-
-#include <sgidefs.h>
-
-#if _MIPS_SIM == _ABIO32 || _MIPS_SIM == _ABIN32
-#define __HAVE_64B_ATOMICS 0
-#else
-#define __HAVE_64B_ATOMICS 1
-#endif
-
-/* MIPS is an LL/SC machine.  However, XLP has a direct atomic exchange
-   instruction which will be used by __atomic_exchange_n.  */
-#ifdef _MIPS_ARCH_XLP
-# define ATOMIC_EXCHANGE_USES_CAS 0
-#else
-# define ATOMIC_EXCHANGE_USES_CAS 1
-#endif
-
-#endif /* atomic-machine.h */
diff --git a/sysdeps/or1k/atomic-machine.h b/sysdeps/or1k/atomic-machine.h
deleted file mode 100644
index 90a10867b3f9cf97a0f2f521f6759a0008ef5b82..0000000000000000000000000000000000000000
--- a/sysdeps/or1k/atomic-machine.h
+++ /dev/null
@@ -1,27 +0,0 @@
-/* Atomic operations.  OpenRISC version.
-   Copyright (C) 2022 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/>.  */
-
-#ifndef __OR1K_ATOMIC_H_
-#define __OR1K_ATOMIC_H_
-
-#include <stdint.h>
-
-#define __HAVE_64B_ATOMICS 0
-#define ATOMIC_EXCHANGE_USES_CAS 1
-
-#endif /* atomic-machine.h */
diff --git a/sysdeps/powerpc/powerpc32/atomic-machine.h b/sysdeps/powerpc/powerpc32/atomic-machine.h
index 6a2aae8bdb34281144e6810924377a6a62857d15..5d1d1ca120530371daaf97d5d0c5b545b2327a78 100644
--- a/sysdeps/powerpc/powerpc32/atomic-machine.h
+++ b/sysdeps/powerpc/powerpc32/atomic-machine.h
@@ -33,6 +33,3 @@
 #endif
 
 #define __ARCH_ACQ_INSTR	"isync"
-
-#define __HAVE_64B_ATOMICS 0
-#define ATOMIC_EXCHANGE_USES_CAS 1
diff --git a/sysdeps/powerpc/powerpc64/atomic-machine.h b/sysdeps/powerpc/powerpc64/atomic-machine.h
index 2932f889c5bc6d0fa49d5ad36875b50c27ad07e9..cdee4b84827bcb8455972302725edb3fb76a744c 100644
--- a/sysdeps/powerpc/powerpc64/atomic-machine.h
+++ b/sysdeps/powerpc/powerpc64/atomic-machine.h
@@ -33,6 +33,3 @@
 #endif
 
 #define __ARCH_ACQ_INSTR	"isync"
-
-#define __HAVE_64B_ATOMICS 1
-#define ATOMIC_EXCHANGE_USES_CAS 1
diff --git a/sysdeps/s390/atomic-machine.h b/sysdeps/s390/atomic-machine.h
deleted file mode 100644
index 3e25dcf44126001382e3b98aa2f82d29e29f1424..0000000000000000000000000000000000000000
--- a/sysdeps/s390/atomic-machine.h
+++ /dev/null
@@ -1,24 +0,0 @@
-/* Copyright (C) 2003-2022 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/>.  */
-
-#ifdef __s390x__
-# define __HAVE_64B_ATOMICS 1
-#else
-# define __HAVE_64B_ATOMICS 0
-#endif
-
-#define ATOMIC_EXCHANGE_USES_CAS 1
diff --git a/sysdeps/sparc/atomic-machine.h b/sysdeps/sparc/atomic-machine.h
index 1f0eb0a9b1171c06dc19dc21c4fe7de94adc4bce..7ea88d598b9a36735004fe03cb52e46fe4807140 100644
--- a/sysdeps/sparc/atomic-machine.h
+++ b/sysdeps/sparc/atomic-machine.h
@@ -19,15 +19,6 @@
 #ifndef _ATOMIC_MACHINE_H
 #define _ATOMIC_MACHINE_H	1
 
-#ifdef __arch64__
-# define __HAVE_64B_ATOMICS          1
-#else
-# define __HAVE_64B_ATOMICS          0
-#endif
-
-/* XXX Is this actually correct?  */
-#define ATOMIC_EXCHANGE_USES_CAS     __HAVE_64B_ATOMICS
-
 #ifdef __sparc_v9__
 
 extern void __cpu_relax (void);
diff --git a/sysdeps/unix/sysv/linux/hppa/atomic-machine.h b/sysdeps/unix/sysv/linux/hppa/atomic-machine.h
deleted file mode 100644
index 9c9fecbefef037e3b7e8c291e722d093b811dd69..0000000000000000000000000000000000000000
--- a/sysdeps/unix/sysv/linux/hppa/atomic-machine.h
+++ /dev/null
@@ -1,27 +0,0 @@
-/* Copyright (C) 2003-2022 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/>.  */
-
-#ifndef _ATOMIC_MACHINE_H
-#define _ATOMIC_MACHINE_H	1
-
-#define __HAVE_64B_ATOMICS 0
-
-/* XXX Is this actually correct?  */
-#define ATOMIC_EXCHANGE_USES_CAS 1
-
-#endif
-/* _ATOMIC_MACHINE_H */
diff --git a/sysdeps/unix/sysv/linux/loongarch/atomic-machine.h b/sysdeps/unix/sysv/linux/loongarch/atomic-machine.h
deleted file mode 100644
index c94144605fcd16c1dd3e35a86eb325e1acb4d282..0000000000000000000000000000000000000000
--- a/sysdeps/unix/sysv/linux/loongarch/atomic-machine.h
+++ /dev/null
@@ -1,27 +0,0 @@
-/* Atomic operations.
-   Copyright (C) 2022 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/>.  */
-
-#ifndef _LINUX_LOONGARCH_BITS_ATOMIC_H
-#define _LINUX_LOONGARCH_BITS_ATOMIC_H 1
-
-#define atomic_full_barrier() __sync_synchronize ()
-
-#define __HAVE_64B_ATOMICS (__loongarch_grlen >= 64)
-#define ATOMIC_EXCHANGE_USES_CAS 0
-
-#endif /* bits/atomic.h */
diff --git a/sysdeps/unix/sysv/linux/m68k/coldfire/atomic-machine.h b/sysdeps/unix/sysv/linux/m68k/coldfire/atomic-machine.h
deleted file mode 100644
index 02e54847a42bfbc93ae1e07b7e32965be644daba..0000000000000000000000000000000000000000
--- a/sysdeps/unix/sysv/linux/m68k/coldfire/atomic-machine.h
+++ /dev/null
@@ -1,28 +0,0 @@
-/* Copyright (C) 2010-2022 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/>.  */
-
-#ifndef _ATOMIC_MACHINE_H
-#define _ATOMIC_MACHINE_H	1
-
-#include <sysdep.h>
-
-#define __HAVE_64B_ATOMICS 0
-
-/* XXX Is this actually correct?  */
-#define ATOMIC_EXCHANGE_USES_CAS 1
-
-#endif
diff --git a/sysdeps/unix/sysv/linux/nios2/atomic-machine.h b/sysdeps/unix/sysv/linux/nios2/atomic-machine.h
deleted file mode 100644
index 4b4b714f93f4c4b9f7f650d70d2301299a45e2f5..0000000000000000000000000000000000000000
--- a/sysdeps/unix/sysv/linux/nios2/atomic-machine.h
+++ /dev/null
@@ -1,27 +0,0 @@
-/* Low-level functions for atomic operations. Nios II version.
-   Copyright (C) 2012-2022 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/>.  */
-
-#ifndef _NIOS2_ATOMIC_MACHINE_H
-#define _NIOS2_ATOMIC_MACHINE_H 1
-
-#define __HAVE_64B_ATOMICS 0
-
-/* XXX Is this actually correct?  */
-#define ATOMIC_EXCHANGE_USES_CAS 1
-
-#endif /* _NIOS2_ATOMIC_MACHINE_H */
diff --git a/sysdeps/unix/sysv/linux/riscv/atomic-machine.h b/sysdeps/unix/sysv/linux/riscv/atomic-machine.h
index b0ebe09ce1fa4e15064dd57d83cadb8a1976f86d..90c48b301e8dad46017fe8d6497756cdd74268c8 100644
--- a/sysdeps/unix/sysv/linux/riscv/atomic-machine.h
+++ b/sysdeps/unix/sysv/linux/riscv/atomic-machine.h
@@ -21,9 +21,6 @@
 
 #ifdef __riscv_atomic
 
-# define __HAVE_64B_ATOMICS (__riscv_xlen >= 64)
-# define ATOMIC_EXCHANGE_USES_CAS 0
-
 /* Miscellaneous.  */
 
 # define asm_amo(which, ordering, mem, value) ({ 		\
diff --git a/sysdeps/unix/sysv/linux/sh/atomic-machine.h b/sysdeps/unix/sysv/linux/sh/atomic-machine.h
deleted file mode 100644
index 71848194daa98ad0391c029a8c7d9dba5ba5fe3d..0000000000000000000000000000000000000000
--- a/sysdeps/unix/sysv/linux/sh/atomic-machine.h
+++ /dev/null
@@ -1,22 +0,0 @@
-/* Atomic operations used inside libc.  Linux/SH version.
-   Copyright (C) 2003-2022 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 __HAVE_64B_ATOMICS 0
-
-/* XXX Is this actually correct?  */
-#define ATOMIC_EXCHANGE_USES_CAS 1
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/Makefile b/sysdeps/unix/sysv/linux/sparc/sparc32/Makefile
index 21c7dc1680caf19cb21a36ade3cb4baaee188159..1b8b1c516ac1e70b36650e00f06c8d2425a4d882 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/Makefile
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/Makefile
@@ -11,7 +11,7 @@ endif
 
 # When I get this to work, this is the right thing
 ifeq ($(subdir),elf)
-CFLAGS-rtld.c += -mcpu=v8
+#CFLAGS-rtld.c += -mcpu=v8 # causes leon3 builds to fail
 #rtld-routines += dl-sysdepsparc
 sysdep-others += lddlibc4
 install-bin += lddlibc4
diff --git a/sysdeps/x86/atomic-machine.h b/sysdeps/x86/atomic-machine.h
index 98541a2d06ff5e4aa8c789ab7405215097471971..303458d1296e4b1cd7cd654e0904ace0ffc52fae 100644
--- a/sysdeps/x86/atomic-machine.h
+++ b/sysdeps/x86/atomic-machine.h
@@ -21,17 +21,6 @@
 
 #include <tls.h>			/* For mach.  */
 
-#ifdef __x86_64__
-# define __HAVE_64B_ATOMICS		1
-#else
-/* Since the Pentium, i386 CPUs have supported 64-bit atomics, but the
-   i386 psABI supplement provides only 4-byte alignment for uint64_t
-   inside structs, so it is currently not possible to use 64-bit
-   atomics on this platform.  */
-# define __HAVE_64B_ATOMICS		0
-#endif
-#define ATOMIC_EXCHANGE_USES_CAS	0
-
 #define atomic_spin_nop() __asm ("pause")
 
 #endif /* atomic-machine.h */