Re: [RFA] Altivec ABI patches

[Elena Zannoni <ezannoni@redhat.com>]

Kevin Buettner writes:
 > On Apr 26,  9:44pm, Elena Zannoni wrote:
 > 
 > >  > Note that the subsequent memcpy() ends up overwriting the memory
 > >  > zero'd by the assignment.  If the assignment does serve some useful
 > >  > purpose, I'd prefer to see memset() used instead.
 > >  > 
 > > 
 > > It does seem odd, I actually just cut and pasted the code from a few
 > > lines above. I thought there was some reason for it, after all.
 > > 
 > > 	    {
 > > 	      *(int *) &registers[REGISTER_BYTE (greg)] = 0;
 > > 	      memcpy (&registers[REGISTER_BYTE (greg)], val_buf, 4);
 > > 	      greg++;
 > > 	    }
 > > 
 > > Should this go as well, then?
 > 
 > Yes, definitely.  As written, this code could yield some very
 > unexpected results on certain hosts.
 > 
 > Thanks for pointing this out.  This is very likely a mistake that I
 > made a while back.
 > 
 > > Unless it always writes 4 bytes, but the
 > > size of the general register can be bigger?
 > 
 > Well, the code in question doesn't work for 64-bit ABIs, but then, as
 > I understand it, the 64-bit PowerPC SVR4 ABI resembles the old PowerOpen
 > ABI than it does the 32-bit SVR4 ABI.  (Actually, I don't know that
 > much about it.  If someone could give me a pointer to an ABI spec for
 > the 64-bit ABI, I would appreciate it very much.)
 > 
 > Kevin


OK, I have removed those 2 statements and committed the rest.

Elena