On Thu, Jun 26, 2025 at 2:17 PM H.J. Lu <hjl.to...@gmail.com> wrote:
>
> On Thu, Jun 26, 2025 at 2:11 PM Hongtao Liu <crazy...@gmail.com> wrote:
> >
> > On Thu, Jun 26, 2025 at 1:59 PM H.J. Lu <hjl.to...@gmail.com> wrote:
> > >
> > > Use the inner scalar mode of vector broadcast source in:
> > >
> > > (set (reg:V8DF 394)
> > > (vec_duplicate:V8DF (reg:V2DF 190 [ alpha ])))
> > >
> > > to compute the vector mode for broadcast from vector source.
> >
> > ix86_get_vector_cse_mode (unsigned int size, machine_mode smode)
> > {
> > + /* Use the inner scalar mode of vector broadcast source in:
> > +
> > + (set (reg:V8DF 394)
> > + (vec_duplicate:V8DF (reg:V2DF 190 [ alpha ])))
> > +
> > + to compute the vector mode for broadcast from vector source.
> > + */
> > + if (VECTOR_MODE_P (smode))
> > + smode = GET_MODE_INNER (smode);
> >
> > I think we need to figure out why vector mode is passed to
> > ix86_get_vector_cse_mode and fix there.
>
> There is nothing wrong with V2DF passed to ix86_get_vector_cse_mode.
> The testcase shows that there are
>
> (insn 14 12 40 3 (set (reg:V8DF 99 [ _11 ])
> (vec_duplicate:V8DF (reg:V2DF 102 [ pretmp_22 ])))
> "x.cc":68:64 9289 {*avx512dq_broadcastv8df_1}
> (expr_list:REG_DEAD (reg:V2DF 102 [ pretmp_22 ])
> (nil)))
> ...
> (insn 28 26 30 5 (set (reg:V8DF 109)
> (vec_duplicate:V8DF (reg:V2DF 102 [ pretmp_22 ])))
> "x.cc":68:64 9289 {*avx512dq_broadcastv8df_1}
> (expr_list:REG_DEAD (reg:V2DF 102 [ pretmp_22 ])
> (nil)))
>
> We add
>
> (insn 44 9 10 2 (set (reg:V8DF 116)
> (vec_duplicate:V8DF (reg:V2DF 102 [ pretmp_22 ]))) "x.cc":44:10 -1
> (nil))
>
> after:
>
> (insn 9 8 44 2 (set (reg:V2DF 102 [ pretmp_22 ])
> (mem/j:V2DF (plus:DI (reg/f:DI 19 frame)
> (const_int -20 [0xffffffffffffffec])) [3 +0 S16 A32]))
> "x.cc":44:10 2429 {movv2df_internal}
> (nil))
>
> to eliminate the redundant V2DF -> V8DF broadcast.
I notice that avx512dq_broadcastv8df_mask_1 allows vector mode as
inner mode of vec_duplicate.
Ok for the patch.
>
> > >
> > > gcc/
> > >
> > > PR target/120830
> > > * config/i386/i386-features.cc (ix86_get_vector_cse_mode): Handle
> > > vector broadcast source.
> > >
> > > gcc/testsuite/
> > >
> > > PR target/120830
> > > * g++.target/i386/pr120830.C: New test.
> > >
> > > OK for master?
> > >
> > > --
> > > H.J.
> >
> >
> >
> > --
> > BR,
> > Hongtao
>
>
>
> --
> H.J.
--
BR,
Hongtao
