unsigned int sp;

void fxn()
{
    /* Compilation fails as the compiler selects a `Dx` register instead of a `Ax` register to load the address of `sp`. */
    __asm volatile("ST.32 *%0, A15" : : "r"(&sp));

}

% c29clang -c file.c
file.c:7:20: error: illegal base register for indirect
    7 |     __asm volatile("ST.32 *%0, A15" : : "r"(&sp));
      |                    ^
<inline asm>:1:11: note: instantiated into assembly here
    1 |         ST.32 *D0, A15
      |                  ^
1 error generated.