------- Additional Comments From joel at oarcorp dot com 2004-11-03 23:25 ------- Subject: Re: M68060 fails with libstdc++-v3/config/cpu/m68k/atomicity.h
cjohns at cybertec dot com dot au wrote: > ------- Additional Comments From cjohns at cybertec dot com dot au 2004-11-03 23:05 > ------- > Does this mean the instruction in question (cas) in atomicity.h cannot be used > on the 68060 if the stack can be aligned to a 2 byte boundary ? Not if the memory to be swapped is on the stack. The memory could be in global memory and be properly aligned. Grrr... I forgot you can do this with GCC: typedef unsigned int _Atomic_word __attribute__ ((aligned (4))); Wouldn't changing the definition for the m68k to the above fix this? > Would a stack aligned this way cause a slow down if the call/ret address being > pushed and popped is not aligned to a 32bit boundary ? I suspect it would but don't know the MC68060 enough to state that authoritatively. > I do not full understand the ABI issues hence my next question. RTEMS + > application is built as a single executable, typically all with the same tool > set, so does an ABI issue exist in our case ? If you can find something in a FreeScale document showing improved performance for aligned accesses on the MC68060, that would tell me that for RTEMS, we want mc68060 to imply stricter alignment. I would bet that others would as well if a performance increase is obtained. --joel -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17627
