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From: Sebastian Huber <sh@sourceware.org> To: newlib-cvs@sourceware.org Subject: [newlib-cygwin] Make the system C11 atomics headers fully compatible with external GCC. Date: Mon, 26 Oct 2020 13:31:27 +0000 (GMT) [thread overview] Message-ID: <20201026133127.8FDC83850412@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=c25de3a3c51e3d27133947a3d943c2a2127445d5 commit c25de3a3c51e3d27133947a3d943c2a2127445d5 Author: jhb <jhb@FreeBSD.org> Date: Mon Aug 6 23:51:08 2018 +0000 Make the system C11 atomics headers fully compatible with external GCC. The <sys/cdefs.h> and <stdatomic.h> headers already included support for C11 atomics via intrinsincs in modern versions of GCC, but these versions tried to "hide" atomic variables inside a wrapper structure. This wrapper is not compatible with GCC's internal <stdatomic.h> header, so that if GCC's <stdatomic.h> was used together with <sys/cdefs.h>, use of C11 atomics would fail to compile. Fix this by not hiding atomic variables in a structure for modern versions of GCC. The headers already avoid using a wrapper structure on clang. Note that this wrapper was only used if C11 was not enabled (e.g. via -std=c99), so this also fixes compile failures if a modern version of GCC was used with -std=c11 but with FreeBSD's <stdatomic.h> instead of GCC's <stdatomic.h> and this change fixes that case as well. Reported by: Mark Millard Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D16585 Diff: --- newlib/libc/include/stdatomic.h | 25 +++++++++++-------------- newlib/libc/include/sys/cdefs.h | 2 +- 2 files changed, 12 insertions(+), 15 deletions(-) diff --git a/newlib/libc/include/stdatomic.h b/newlib/libc/include/stdatomic.h index 09c0cf73e..1441c9e3b 100644 --- a/newlib/libc/include/stdatomic.h +++ b/newlib/libc/include/stdatomic.h @@ -169,12 +169,9 @@ atomic_signal_fence(memory_order __order __unused) /* Atomics in kernelspace are always lock-free. */ #define atomic_is_lock_free(obj) \ ((void)(obj), (_Bool)1) -#elif defined(__CLANG_ATOMICS) +#elif defined(__CLANG_ATOMICS) || defined(__GNUC_ATOMICS) #define atomic_is_lock_free(obj) \ __atomic_is_lock_free(sizeof(*(obj)), obj) -#elif defined(__GNUC_ATOMICS) -#define atomic_is_lock_free(obj) \ - __atomic_is_lock_free(sizeof((obj)->__val), &(obj)->__val) #else #define atomic_is_lock_free(obj) \ ((void)(obj), sizeof((obj)->__val) <= sizeof(void *)) @@ -260,28 +257,28 @@ typedef _Atomic(uintmax_t) atomic_uintmax_t; #elif defined(__GNUC_ATOMICS) #define atomic_compare_exchange_strong_explicit(object, expected, \ desired, success, failure) \ - __atomic_compare_exchange_n(&(object)->__val, expected, \ + __atomic_compare_exchange_n(object, expected, \ desired, 0, success, failure) #define atomic_compare_exchange_weak_explicit(object, expected, \ desired, success, failure) \ - __atomic_compare_exchange_n(&(object)->__val, expected, \ + __atomic_compare_exchange_n(object, expected, \ desired, 1, success, failure) #define atomic_exchange_explicit(object, desired, order) \ - __atomic_exchange_n(&(object)->__val, desired, order) + __atomic_exchange_n(object, desired, order) #define atomic_fetch_add_explicit(object, operand, order) \ - __atomic_fetch_add(&(object)->__val, operand, order) + __atomic_fetch_add(object, operand, order) #define atomic_fetch_and_explicit(object, operand, order) \ - __atomic_fetch_and(&(object)->__val, operand, order) + __atomic_fetch_and(object, operand, order) #define atomic_fetch_or_explicit(object, operand, order) \ - __atomic_fetch_or(&(object)->__val, operand, order) + __atomic_fetch_or(object, operand, order) #define atomic_fetch_sub_explicit(object, operand, order) \ - __atomic_fetch_sub(&(object)->__val, operand, order) + __atomic_fetch_sub(object, operand, order) #define atomic_fetch_xor_explicit(object, operand, order) \ - __atomic_fetch_xor(&(object)->__val, operand, order) + __atomic_fetch_xor(object, operand, order) #define atomic_load_explicit(object, order) \ - __atomic_load_n(&(object)->__val, order) + __atomic_load_n(object, order) #define atomic_store_explicit(object, desired, order) \ - __atomic_store_n(&(object)->__val, desired, order) + __atomic_store_n(object, desired, order) #else #define __atomic_apply_stride(object, operand) \ (((__typeof__((object)->__val))0) + (operand)) diff --git a/newlib/libc/include/sys/cdefs.h b/newlib/libc/include/sys/cdefs.h index ccb47ea40..9a0466fff 100644 --- a/newlib/libc/include/sys/cdefs.h +++ b/newlib/libc/include/sys/cdefs.h @@ -288,7 +288,7 @@ #endif #if !defined(__cplusplus) && !__has_extension(c_atomic) && \ - !__has_extension(cxx_atomic) + !__has_extension(cxx_atomic) && !__GNUC_PREREQ__(4, 7) /* * No native support for _Atomic(). Place object in structure to prevent * most forms of direct non-atomic access.
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