On Sun, Mar 20, 2011 at 10:08 PM, Mike Frysinger <vap...@gentoo.org> wrote: > On Thursday, March 17, 2011 01:21:16 H.J. Lu wrote: >> On Wed, Mar 16, 2011 at 7:57 PM, Mike Frysinger <vap...@gentoo.org> wrote: >> > in looking at the gcc files, it doesnt seem like there's any defines >> > setup to declare x32 directly. instead, you'd have to do something >> > like: #ifdef __x86_64__ >> > # if __SIZEOF_LONG__ == 8 >> > /* x86_64 */ >> > # else >> > /* x32 */ >> > # endif >> > #endif >> > >> > any plans on adding an __x32__ (or whatever) cpp symbol to keep people >> > from coming up with their own special/broken crap ? or are there some >> > already that i'm not seeing ? >> >> The idea is in most cases, you only need to check __x86_64__ since x32 and >> x86-64 are very close. In some cases, x32 is very different from x86_64, >> like assembly codes on long and pointer, you can check __x86_64__ and >> __LP64__. In glibc, I used a different approach by using macros REG_RAX, >> .., MOV_LP, ADD_LP, SUB_LP and CMP_LP in assembly codes. > > while i agree with you in general that this is how people should be doing > things, in practice i often see people fishing around. education only goes so > far, so if there was an __x32__ define, i feel like people are more likely to > get it right than wrong. > > i dont have any use cases off the top of my head, but i wouldnt be surprised > if the heavy inline assembly people (like the multimedia peeps e.g. libav) > approached it this way. rather than google for documentation, look at the cpp > output between -m64 and -mx32 and see what sticks out. "__x32__" would > certainly do that.
My point is __x86_64__ version should work for both 64bit and x32. There should no need for a separate x32 version. -- H.J.
