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Re: [PATCH, rs6000] Fix order of TDmode in FPRs in little-endian mode


David Edelsohn wrote:
> On Mon, Nov 18, 2013 at 3:07 PM, Ulrich Weigand <uweigand@de.ibm.com> wrote:
> > Also note that this patch does not change how TDmode values are loaded
> > into GPRs: on little-endian, this means we do get the usual LE subreg
> > order there (least significant word in lowest-numbered register).  This
> > does still seem the right thing to do, because there are no instructions
> > that operate on DFP values in GPRs, and because this allows us to keep
> > using subregs on GPRs in that case, and it allows moving TDmode between
> > memory and GPRs (e.g. for vararg arguments) in the usual way.
> 
> Does this require special support in GDB so that it understands how to
> interpret this type in different classes of registers?  However, the
> interpretation always will be consistent for a particular class of
> register.

Ah, good point.  Yes, GDB will need to be changed, but this looks
to be straightforward.  GDB already uses "pseudo" registers to
represent _Decimal128 in FPR pairs, they simply need to be glued
together the right way on little-endian.  I'll fix this.

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  GNU/Linux compilers and toolchain
  Ulrich.Weigand@de.ibm.com


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