On Mon, Feb 11, 2019 at 2:04 AM H.J. Lu <hjl.to...@gmail.com> wrote:
>
> On Sun, Feb 10, 2019 at 1:49 PM Uros Bizjak <ubiz...@gmail.com> wrote:
> >
> > On Sun, Feb 10, 2019 at 10:45 PM Uros Bizjak <ubiz...@gmail.com> wrote:
> >
> > > > > > + [(const_int 0)]
> > > > > > +{
> > > > > > + /* Emulate MMX vec_dupv2si with SSE vec_dupv4si. */
> > > > > > + rtx op0 = gen_rtx_REG (V4SImode, REGNO (operands[0]));
> > > > > > + rtx insn = gen_vec_dupv4si (op0, operands[1]);
> > > > > > + emit_insn (insn);
> > > > > > + DONE;
> > > > >
> > > > > Please write this simple RTX explicitly in the place of (const_int 0)
> > > > > above.
> > > >
> > > > rtx insn = gen_vec_dupv4si (op0, operands[1]);
> > > >
> > > > is easy. How do I write
> > > >
> > > > rtx op0 = gen_rtx_REG (V4SImode, REGNO (operands[0]));
> > > >
> > > > in place of (const_int 0)?
> > >
> > > [(set (match_dup 2)
> > > (vec_duplicate:V4SI (match_dup 1)))]
> > >
> > > with
> > >
> > > "operands[2] = gen_rtx_REG (V4SImode, REGNO (operands[0]));"
> > >
> > > or even better:
> > >
> > > "operands[2] = gen_lowpart (V4SImode, operands[0]);"
> > >
> > > in the preparation statement.
> >
> > Even shorter is
> >
> > "operands[0] = gen_lowpart (V4SImode, operands[0]);"
> >
> > and use (match_dup 0) instead of (match_dup 2) in the RTX.
> >
> > There is plenty of examples throughout sse.md.
> >
>
> This works:
>
> (define_insn_and_split "*vec_dupv2si"
> [(set (match_operand:V2SI 0 "register_operand" "=y,x,Yv")
> (vec_duplicate:V2SI
> (match_operand:SI 1 "register_operand" "0,0,Yv")))]
> "TARGET_MMX || TARGET_MMX_WITH_SSE"
> "@
> punpckldq\t%0, %0
> #
> #"
> "TARGET_MMX_WITH_SSE && reload_completed"
> [(set (match_dup 0)
> (vec_duplicate:V4SI (match_dup 1)))]
> "operands[0] = gen_rtx_REG (V4SImode, REGNO (operands[0]));"
> [(set_attr "mmx_isa" "native,x64_noavx,x64_avx")
> (set_attr "type" "mmxcvt,ssemov,ssemov")
> (set_attr "mode" "DI,TI,TI")])
If it works, then gen_lowpart is preferred due to extra checks.
However, it would result in a paradoxical subreg, so I wonder if these
extra checks allow this transformation.
Uros.
