On Thu, Sep 05, 2002 at 04:09:11PM +0200, Maciej W. Rozycki wrote: > On Thu, 5 Sep 2002, Kevin D. Kissell wrote: > > > n32 has the same data types as o32, an "ILP32" C integer > > model. n64 is a pretty normal "LP64" C integer model. > > > > What do you consider to be broken, and how would you > > have preferred it to have been done? > > For n32 it would be natural to have: > > - sizeof(int) = 32 > > - sizeof(long) = 64 > > - sizeof(void *) = 32 > > as the underlying hardware directly supports 64-bit operations (n32 > requires at least MIPS III). Thus there is no penalty for 64-bit > arithmetics and if one uses longs one normally wants the largest native > integer type -- using long long typically (i.e. on most platforms) implies > double-precision arithmetics with all the drawbacks, especially for the > division and multiplication operations. > > With 32-bit long on 64-bit hardware software has no easy way to figure > using 64-bit operations is still optimal performance-wise. I can't see > any technical benefit from such a setup -- is there any? I doubt it. Well, here's one - while we all know that C code which assumes a pointer and int are the same size is buggy, it makes everything substantially simpler if long and void* are the same size. That's true for both normal LP64 and ILP32 models. Since n32 was mostly a transitional tool (SGI was primarily interested in n64 as I understand it), I imagine they wanted path of least damage... -- Daniel Jacobowitz MontaVista Software Debian GNU/Linux Developer
