GCC-Inline-Assembly-HOWTO

       asm ( assembler template
           : output operands                  /* optional */
           : input operands                   /* optional */
           : list of clobbered registers      /* optional */
           );

A clobbered register is a register which is trashed i.e. modified in unpredictable way by inline assembler. This usually happens when you need a temp.

fsanitize=address

fsanitize=thread