On Wed, Jul 29, 2015 at 05:46:42PM -0500, Segher Boessenkool wrote:
> On Wed, Jul 29, 2015 at 06:38:45PM -0400, Michael Meissner wrote:
> > On Wed, Jul 29, 2015 at 04:59:23PM -0500, Segher Boessenkool wrote:
> > > On Wed, Jul 29, 2015 at 04:04:28PM -0400, Michael Meissner wrote:
> > > > +;; Return constant 0x80000000000000000000000000000000 in an Altivec
> > > > register.
> > > > +
> > > > +(define_expand "altivec_high_bit"
> > > > + [(set (match_dup 1)
> > > > + (vec_duplicate:V16QI (const_int 7)))
> > > > + (set (match_dup 2)
> > > > + (ashift:V16QI (match_dup 1)
> > > > + (match_dup 1)))
> > > > + (set (match_dup 3)
> > > > + (match_dup 4))
> > > > + (set (match_operand:V16QI 0 "register_operand" "")
> > > > + (unspec:V16QI [(match_dup 2)
> > > > + (match_dup 3)
> > > > + (const_int 15)] UNSPEC_VSLDOI))]
> > > > + "TARGET_ALTIVEC"
> > > > +{
> > > > + if (can_create_pseudo_p ())
> > > > + {
> > > > + operands[1] = gen_reg_rtx (V16QImode);
> > > > + operands[2] = gen_reg_rtx (V16QImode);
> > > > + operands[3] = gen_reg_rtx (V16QImode);
> > > > + }
> > > > + else
> > > > + operands[1] = operands[2] = operands[3] = operands[0];
> > >
> > > This won't work (in the pattern you write to op 3 before reading from op
> > > 2).
> > > Do you ever call this expander late, anyway?
> >
> > I'm not sure I follow you.
>
> I'm sorry, I meant that very last line I quoted, the !can_create_pseudo_p ()
> one. If that is executed operands[2] will be the same reg as operands[3],
> and things fall apart.
Yes, you are right. I'll put an abort in there if we can't allocate
pseudos. But since it is called during RTL expansion of abskf2, negkf2, etc. we
won't run into it. Thanks.
--
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meiss...@linux.vnet.ibm.com, phone: +1 (978) 899-4797
