Confusion about different clobber description for arm inline assembly

I'm learning ARM inline assembly, and is confused about a very simple function: assign the value of x to y (both are int type), on arm32 and arm64 why different clobber description required?

Here is the code:

#include <arm_neon.h>
#include <stdio.h>

void asm_test()
{
    int x = 10;
    int y = 0;

#ifdef __aarch64__
    asm volatile(
        "mov %w[in], %w[out]"
        : [out] "=r"(y)
        : [in] "r"(x)
        : "r0" // r0 not working, but r1 or x1 works
    );
#else
    asm volattile(
        "mov %[in], %[out]"
        : [out] "=r"(y)
        : [in] "r"(x)
        : "r0"    // r0 works, but r1 not working
    );
#endif
    printf("y is %d\n", y);
}

int main() {
    arm_test();

    return 0;
}

Tested on my rooted android phone, for arm32, r0 generates correct result but r1 won't. For arm64, r1 or x1 generate correct result, and r0 won't. Why on arm32 and arm64 they are different? What is the concrete rule for this and where can I find it?