pgsql: Add RISC-V spinlock support in s_lock.h.

Add RISC-V spinlock support in s_lock.h.

Like the ARM case, just use gcc's __sync_lock_test_and_set();
that will compile into AMOSWAP.W.AQ which does what we need.

At some point it might be worth doing some work on atomic ops
for RISC-V, but this should be enough for a creditable port.

Back-patch to all supported branches, just in case somebody
wants to try them on RISC-V.

Marek Szuba

Discussion: https://postgr.es/m/dea97b6d-f55f-1f6d-9109-504aa7dfa421@gentoo.org

Branch
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REL_10_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/7915a9515cfb867d34c45f564daf70888274929f

Modified Files
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src/include/storage/s_lock.h | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)