On Sat, Jul 21, 2012 at 10:56 AM, Iain Sandoe <i...@codesourcery.com> wrote: > Hi Mike, > > On 21 Jul 2012, at 18:27, Mike Stump wrote: > >> On Jul 21, 2012, at 9:12 AM, Iain Sandoe wrote: >>> At present, if a G5 or 970 processor is selected (-mcpu=), we can (and do) >>> generate 64 bit register usage for m32 code. This appears to be a >>> long-standing bug. >> >> Hum, do you have an example of something that fails? > > I can look for something, if necessary. > >> I ask, cause I think the if you say that you have a 64-bit processor, then, >> generating code for a 64-bit processor isn't necessarily wrong. > > indeed, highly desirable to make use of any improvements available. > >> If you say you have a 64-bit processor, then you likely have an OS that runs >> on that processor, and that OS I'm thinking will save and restore the full >> 64-bit registers. If not, do you have a pointer to documentation that says >> this won't work? > > Mac_OS_X_ABI_Function_Calls.pdf pp 19 para 2 (box). This stipulates that > even on a 64 bit processor, only the lower 32 bits of nonvolatile registers > are saved/restored. All 64 bits are saved across context > switches/asynchronous events. > > That is to quote the doc: one can *only* use the full 64 bits 'between > function calls' safely. > > If there's a different mechanism for enforcing what's implied above, then we > could use
Yes HARD_REGNO_CALL_PART_CLOBBERED should work. If that is not working there is a bug somewhere else in the compiler. Thanks, Andrew Pinski
