https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67334
--- Comment #2 from anmin_deng at yahoo dot com.tw --- In the said test code, variable "b" is never used later so in the 2nd "__asm__" (with "adds" and "adc" instructions), there is no proper dependency described between the 2 instructions. Problem fixed if separating the 2nd "__asm__" into 2 "__asm__"s (However, keyword "volatile" must be provided, or "adds" and "adc" instructions would be in incorrect order in generated result).