6.3.9. Memory access atomicity

An aligned memory access, using a single general-purpose register, is guaranteed to be atomic. Load pair and store pair instructions to a pair of general-purpose registers, using an aligned memory address are guaranteed to appear as two individual atomic accesses. Unaligned accesses are not atomic, as they typically require two separate accesses. Additionally, floating-point and SIMD memory accesses are not guaranteed to be atomic.

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