gcc/libatomic/config
Tamar Christina 5471f55f00 AArch32: Fix 128-bit sequential consistency atomic operations.
Similar to AArch64 the Arm implementation of 128-bit atomics is broken.

For 128-bit atomics we rely on pthread barriers to correct guard the address
in the pointer to get correct memory ordering.  However for 128-bit atomics the
address under the lock is different from the original pointer.

This means that one of the values under the atomic operation is not protected
properly and so we fail during when the user has requested sequential
consistency as there's no barrier to enforce this requirement.

As such users have resorted to adding an

#ifdef GCC
<emit barrier>
#endif

around the use of these atomics.

This corrects the issue by issuing a barrier only when __ATOMIC_SEQ_CST was
requested.  I have hand verified that the barriers are inserted
for atomic seq cst.

libatomic/ChangeLog:

	PR target/102218
	* config/arm/host-config.h (pre_seq_barrier, post_seq_barrier,
	pre_post_seq_barrier): Require barrier on __ATOMIC_SEQ_CST.
2022-08-08 14:37:42 +01:00
..
aarch64 AArch64: Fix 128-bit sequential consistency atomic operations. 2022-08-08 14:37:00 +01:00
arm AArch32: Fix 128-bit sequential consistency atomic operations. 2022-08-08 14:37:42 +01:00
ia64
linux Update copyright years. 2022-01-03 10:42:10 +01:00
mingw Update copyright years. 2022-01-03 10:42:10 +01:00
nvptx Update copyright years. 2022-01-03 10:42:10 +01:00
posix Update copyright years. 2022-01-03 10:42:10 +01:00
powerpc
rtems Update copyright years. 2022-01-03 10:42:10 +01:00
s390 Update copyright years. 2022-01-03 10:42:10 +01:00
x86 libatomic: Improve 16-byte atomics on Intel AVX [PR104688] 2022-03-17 18:49:00 +01:00
t-aix aix: remove libgomp and libatomic archives before creating FAT archives 2020-10-11 17:30:24 -04:00