Re: [lttng-dev] [PATCH 02/11] urcu/uatomic: Use atomic builtins if configured

On Mon, May 15, 2023 at 04:17:09PM -0400, Olivier Dion wrote:
> Implement uatomic in term of atomic builtins if configured to do so.
> 
> Change-Id: I5814494c62ee507fd5d381c3ba4ccd0a80c4f4e3
> Co-authored-by: Mathieu Desnoyers <[email protected]>
> Signed-off-by: Olivier Dion <[email protected]>
> ---
>  include/Makefile.am                     |  3 +
>  include/urcu/uatomic.h                  |  5 +-
>  include/urcu/uatomic/builtins-generic.h | 85 +++++++++++++++++++++++++
>  include/urcu/uatomic/builtins-x86.h     | 85 +++++++++++++++++++++++++
>  include/urcu/uatomic/builtins.h         | 83 ++++++++++++++++++++++++
>  5 files changed, 260 insertions(+), 1 deletion(-)
>  create mode 100644 include/urcu/uatomic/builtins-generic.h
>  create mode 100644 include/urcu/uatomic/builtins-x86.h
>  create mode 100644 include/urcu/uatomic/builtins.h
> 
> diff --git a/include/Makefile.am b/include/Makefile.am
> index ba1fe60..fac941f 100644
> --- a/include/Makefile.am
> +++ b/include/Makefile.am
> @@ -63,6 +63,9 @@ nobase_include_HEADERS = \
>  	urcu/uatomic/alpha.h \
>  	urcu/uatomic_arch.h \
>  	urcu/uatomic/arm.h \
> +	urcu/uatomic/builtins.h \
> +	urcu/uatomic/builtins-generic.h \
> +	urcu/uatomic/builtins-x86.h \
>  	urcu/uatomic/gcc.h \
>  	urcu/uatomic/generic.h \
>  	urcu/uatomic.h \
> diff --git a/include/urcu/uatomic.h b/include/urcu/uatomic.h
> index 2fb5fd4..6b57c5f 100644
> --- a/include/urcu/uatomic.h
> +++ b/include/urcu/uatomic.h
> @@ -22,8 +22,11 @@
>  #define _URCU_UATOMIC_H
>  
>  #include <urcu/arch.h>
> +#include <urcu/config.h>
>  
> -#if defined(URCU_ARCH_X86)
> +#if defined(CONFIG_RCU_USE_ATOMIC_BUILTINS)
> +#include <urcu/uatomic/builtins.h>
> +#elif defined(URCU_ARCH_X86)
>  #include <urcu/uatomic/x86.h>
>  #elif defined(URCU_ARCH_PPC)
>  #include <urcu/uatomic/ppc.h>
> diff --git a/include/urcu/uatomic/builtins-generic.h b/include/urcu/uatomic/builtins-generic.h
> new file mode 100644
> index 0000000..8e6a9b5
> --- /dev/null
> +++ b/include/urcu/uatomic/builtins-generic.h
> @@ -0,0 +1,85 @@
> +/*
> + * urcu/uatomic/builtins-generic.h
> + *
> + * Copyright (c) 2023 Olivier Dion <[email protected]>
> + *
> + * This 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.
> + *
> + * This 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 this library; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +#ifndef _URCU_UATOMIC_BUILTINS_GENERIC_H
> +#define _URCU_UATOMIC_BUILTINS_GENERIC_H
> +
> +#include <urcu/system.h>
> +
> +#define uatomic_set(addr, v) __atomic_store_n(addr, v, __ATOMIC_RELAXED)
> +
> +#define uatomic_read(addr) __atomic_load_n(addr, __ATOMIC_RELAXED)

Does this lose the volatile semantics that the old-style definitions
had?

> +
> +#define uatomic_cmpxchg(addr, old, new)					\
> +	__extension__							\
> +	({								\
> +		__typeof__(*(addr)) _old = (__typeof__(*(addr)))old;	\
> +		__atomic_compare_exchange_n(addr, &_old, new, 0,	\
> +					    __ATOMIC_SEQ_CST,		\
> +					    __ATOMIC_SEQ_CST);		\
> +		_old;							\
> +	})
> +
> +#define uatomic_xchg(addr, v)				\
> +	__atomic_exchange_n(addr, v, __ATOMIC_SEQ_CST)
> +
> +#define uatomic_add_return(addr, v)			\
> +	__atomic_add_fetch(addr, v, __ATOMIC_SEQ_CST)
> +
> +#define uatomic_sub_return(addr, v)			\
> +	__atomic_sub_fetch(addr, v, __ATOMIC_SEQ_CST)
> +
> +#define uatomic_and(addr, mask)					\
> +	(void)__atomic_and_fetch(addr, mask, __ATOMIC_RELAXED)
> +
> +#define uatomic_or(addr, mask)					\
> +	(void)__atomic_or_fetch(addr, mask, __ATOMIC_RELAXED)
> +
> +#define uatomic_add(addr, v)					\
> +	(void)__atomic_add_fetch(addr, v, __ATOMIC_RELAXED)
> +
> +#define uatomic_sub(addr, v)					\
> +	(void)__atomic_sub_fetch(addr, v, __ATOMIC_RELAXED)
> +
> +#define uatomic_inc(addr)					\
> +	(void)__atomic_add_fetch(addr, 1, __ATOMIC_RELAXED)
> +
> +#define uatomic_dec(addr)					\
> +	(void)__atomic_sub_fetch(addr, 1, __ATOMIC_RELAXED)
> +
> +#define cmm_smp_mb__before_uatomic_and() cmm_smp_mb()
> +#define cmm_smp_mb__after_uatomic_and()  cmm_smp_mb()
> +
> +#define cmm_smp_mb__before_uatomic_or() cmm_smp_mb()
> +#define cmm_smp_mb__after_uatomic_or()  cmm_smp_mb()
> +
> +#define cmm_smp_mb__before_uatomic_add() cmm_smp_mb()
> +#define cmm_smp_mb__after_uatomic_add()  cmm_smp_mb()
> +
> +#define cmm_smp_mb__before_uatomic_sub() cmm_smp_mb()
> +#define cmm_smp_mb__after_uatomic_sub()  cmm_smp_mb()
> +
> +#define cmm_smp_mb__before_uatomic_inc() cmm_smp_mb()
> +#define cmm_smp_mb__after_uatomic_inc() cmm_smp_mb()
> +
> +#define cmm_smp_mb__before_uatomic_dec() cmm_smp_mb()
> +#define cmm_smp_mb__after_uatomic_dec() cmm_smp_mb()
> +
> +#endif /* _URCU_UATOMIC_BUILTINS_GENERIC_H */
> diff --git a/include/urcu/uatomic/builtins-x86.h b/include/urcu/uatomic/builtins-x86.h
> new file mode 100644
> index 0000000..a70f922
> --- /dev/null
> +++ b/include/urcu/uatomic/builtins-x86.h
> @@ -0,0 +1,85 @@
> +/*
> + * urcu/uatomic/builtins-x86.h
> + *
> + * Copyright (c) 2023 Olivier Dion <[email protected]>
> + *
> + * This 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.
> + *
> + * This 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 this library; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +#ifndef _URCU_UATOMIC_BUILTINS_X86_H
> +#define _URCU_UATOMIC_BUILTINS_X86_H
> +
> +#include <urcu/system.h>
> +
> +#define uatomic_set(addr, v) __atomic_store_n(addr, v, __ATOMIC_RELAXED)
> +
> +#define uatomic_read(addr) __atomic_load_n(addr, __ATOMIC_RELAXED)

And same question here.

							Thanx, Paul

> +
> +#define uatomic_cmpxchg(addr, old, new)					\
> +	__extension__							\
> +	({								\
> +		__typeof__(*(addr)) _old = (__typeof__(*(addr)))old;	\
> +		__atomic_compare_exchange_n(addr, &_old, new, 0,	\
> +					    __ATOMIC_SEQ_CST,		\
> +					    __ATOMIC_SEQ_CST);		\
> +		_old;							\
> +	})
> +
> +#define uatomic_xchg(addr, v)				\
> +	__atomic_exchange_n(addr, v, __ATOMIC_SEQ_CST)
> +
> +#define uatomic_add_return(addr, v)			\
> +	__atomic_add_fetch(addr, v, __ATOMIC_SEQ_CST)
> +
> +#define uatomic_sub_return(addr, v)			\
> +	__atomic_sub_fetch(addr, v, __ATOMIC_SEQ_CST)
> +
> +#define uatomic_and(addr, mask)					\
> +	(void)__atomic_and_fetch(addr, mask, __ATOMIC_SEQ_CST)
> +
> +#define uatomic_or(addr, mask)					\
> +	(void)__atomic_or_fetch(addr, mask, __ATOMIC_SEQ_CST)
> +
> +#define uatomic_add(addr, v)					\
> +	(void)__atomic_add_fetch(addr, v, __ATOMIC_SEQ_CST)
> +
> +#define uatomic_sub(addr, v)					\
> +	(void)__atomic_sub_fetch(addr, v, __ATOMIC_SEQ_CST)
> +
> +#define uatomic_inc(addr)					\
> +	(void)__atomic_add_fetch(addr, 1, __ATOMIC_SEQ_CST)
> +
> +#define uatomic_dec(addr)					\
> +	(void)__atomic_sub_fetch(addr, 1, __ATOMIC_SEQ_CST)
> +
> +#define cmm_smp_mb__before_uatomic_and() do { } while (0)
> +#define cmm_smp_mb__after_uatomic_and()  do { } while (0)
> +
> +#define cmm_smp_mb__before_uatomic_or() do { } while (0)
> +#define cmm_smp_mb__after_uatomic_or()  do { } while (0)
> +
> +#define cmm_smp_mb__before_uatomic_add() do { } while (0)
> +#define cmm_smp_mb__after_uatomic_add()  do { } while (0)
> +
> +#define cmm_smp_mb__before_uatomic_sub() do { } while (0)
> +#define cmm_smp_mb__after_uatomic_sub()  do { } while (0)
> +
> +#define cmm_smp_mb__before_uatomic_inc() do { } while (0)
> +#define cmm_smp_mb__after_uatomic_inc()  do { } while (0)
> +
> +#define cmm_smp_mb__before_uatomic_dec() do { } while (0)
> +#define cmm_smp_mb__after_uatomic_dec()  do { } while (0)
> +
> +#endif /* _URCU_UATOMIC_BUILTINS_X86_H */
> diff --git a/include/urcu/uatomic/builtins.h b/include/urcu/uatomic/builtins.h
> new file mode 100644
> index 0000000..164201b
> --- /dev/null
> +++ b/include/urcu/uatomic/builtins.h
> @@ -0,0 +1,83 @@
> +/*
> + * urcu/uatomic/builtins.h
> + *
> + * Copyright (c) 2023 Olivier Dion <[email protected]>
> + *
> + * This 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.
> + *
> + * This 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 this library; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +#ifndef _URCU_UATOMIC_BUILTINS_H
> +#define _URCU_UATOMIC_BUILTINS_H
> +
> +#include <urcu/arch.h>
> +
> +#if defined(__has_builtin)
> +#  if !__has_builtin(__atomic_store_n)
> +#    error "Toolchain does not support __atomic_store_n."
> +#  endif
> +#  if !__has_builtin(__atomic_load_n)
> +#    error "Toolchain does not support __atomic_load_n."
> +#  endif
> +#  if !__has_builtin(__atomic_exchange_n)
> +#    error "Toolchain does not support __atomic_exchange_n."
> +#  endif
> +#  if !__has_builtin(__atomic_compare_exchange_n)
> +#    error "Toolchain does not support __atomic_compare_exchange_n."
> +#  endif
> +#  if !__has_builtin(__atomic_add_fetch)
> +#    error "Toolchain does not support __atomic_add_fetch."
> +#  endif
> +#  if !__has_builtin(__atomic_sub_fetch)
> +#    error "Toolchain does not support __atomic_sub_fetch."
> +#  endif
> +#  if !__has_builtin(__atomic_or_fetch)
> +#    error "Toolchain does not support __atomic_or_fetch."
> +#  endif
> +#  if !__has_builtin(__atomic_thread_fence)
> +#    error "Toolchain does not support __atomic_thread_fence."
> +#  endif
> +#  if !__has_builtin(__atomic_signal_fence)
> +#    error "Toolchain does not support __atomic_signal_fence."
> +#  endif
> +#elif defined(__GNUC__)
> +#  define GCC_VERSION (__GNUC__       * 10000 + \
> +		       __GNUC_MINOR__ * 100   + \
> +		       __GNUC_PATCHLEVEL__)
> +#  if  GCC_VERSION < 40700
> +#    error "GCC version is too old. Version must be 4.7 or greater"
> +#  endif
> +#  undef  GCC_VERSION
> +#else
> +#  error "Toolchain is not supported."
> +#endif
> +
> +#if defined(__GNUC__)
> +#  define UATOMIC_HAS_ATOMIC_BYTE  __GCC_ATOMIC_CHAR_LOCK_FREE
> +#  define UATOMIC_HAS_ATOMIC_SHORT __GCC_ATOMIC_SHORT_LOCK_FREE
> +#elif defined(__clang__)
> +#  define UATOMIC_HAS_ATOMIC_BYTE  __CLANG_ATOMIC_CHAR_LOCK_FREE
> +#  define UATOMIC_HAS_ATOMIC_SHORT __CLANG_ATOMIC_SHORT_LOCK_FREE
> +#else
> +/* #  define UATOMIC_HAS_ATOMIC_BYTE  */
> +/* #  define UATOMIC_HAS_ATOMIC_SHORT */
> +#endif
> +
> +#if defined(URCU_ARCH_X86)
> +#  include <urcu/uatomic/builtins-x86.h>
> +#else
> +#  include <urcu/uatomic/builtins-generic.h>
> +#endif
> +
> +#endif	/* _URCU_UATOMIC_BUILTINS_H */
> -- 
> 2.39.2
> 
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