On 05/17/2016 01:01 PM, Sergey Fedorov wrote: >> Sorry, I can't see reading ARMv6 ARM that 1-byte access can't be atomic. What >> I've found: >> >> B2.4.1 Normal memory attribute >> (snip) >> Shared Normal memory >> >> (snip) >> ... Reads to Shared Normal Memory that are aligned in memory to the >> size of the access must be atomic. ... > Looks like GCC has no trouble generating __atomic_store_n() for 1-byte bool...
Not loads and stores, but other atomic ops like xchg. The native atomic operations are all 4 bytes long. I suppose the compiler may well be able to synthesize sub-word atomic ops, but it'll be 2 or 3 times the size of a word-sized atomic op, and for no good reason. r~
