Your result is hardly surprising as Apple M1 is a different CPU architecture using the ARM instruction set. It is unlikely that the CPU circuitry related to this particular function would be similar to Intel x86. This might not even work with an AMD x86 CPU.

Out of curiosity, can you dump the relevant disassembly of the square_am_signal function (using `$ objdump -d mybinary`)?

Note that this instruction (_mm_stream_si128) is a SSE instruction that will write 128 bits to memory, more or less bypassing the cache (as long as you write whole cache lines). This instruction is highly specific to the memory architecture in Intel x86 CPUs. When compiling for ARM, I expect that this will just be compiled to a regular store instruction.