Mixing C and assembly and its impact on registers

Consider the following C and (ARM) assembly snippet, which is to be compiled with GCC:

__asm__ __volatile__ (
        "vldmia.64 %[data_addr]!, {d0-d1}\n\t"
        "vmov.f32 q12, #0.0\n\t"
        : [data_addr] "+r" (data_addr)
        : : "q0", "q12");

for(int n=0; n<10; ++n){
    __asm__ __volatile__ (
            "vadd.f32 q12, q12, q0\n\t"
            "vldmia.64 %[data_addr]!, {d0-d1}\n\t"
            : [data_addr] "+r" (data_addr),
            :: "q0", "q12");
}

In this example, I am initialising some SIMD registers outside the loop and then having C handle the loop logic, with those initialised registers being used inside the loop.

This works in some test code, but I'm concerned of the risk of the compiler clobbering the registers between snippets. Is there any way of ensuring this doesn't happen? Can I infer any assurances about the type of registers that are going to be used in a snippet (in this case, that no SIMD registers will be clobbered)?