On Mon, Oct 19, 2020 at 5:07 PM Richard Biener
<richard.guent...@gmail.com> wrote:
>
> On Mon, Oct 19, 2020 at 10:21 AM Hongtao Liu <crazy...@gmail.com> wrote:
> >
> > Hi:
> > It's implemented as below:
> > V setg (V v, int idx, T val)
> >
> > {
> > V idxv = (V){idx, idx, idx, idx, idx, idx, idx, idx};
> > V valv = (V){val, val, val, val, val, val, val, val};
> > V mask = ((V){0, 1, 2, 3, 4, 5, 6, 7} == idxv);
> > v = (v & ~mask) | (valv & mask);
> > return v;
> > }
> >
> > Bootstrap is fine, regression test for i386/x86-64 backend is ok.
> > Ok for trunk?
>
> Hmm, I guess you're trying to keep the code for !AVX512BW simple
> but isn't just splitting the compare into
>
> clow = {0, 1, 2, 3 ... } == idxv
> chigh = {16, 17, 18, ... } == idxv;
> cmp = {clow, chigh}
>
We also don't have 512-bits byte/word blend instructions without
TARGET_AVX512W, so how to use 512-bits cmp?
cut from i386-expand.c:
in ix86_expand_sse_movcc
3682 case E_V64QImode:
3683 gen = gen_avx512bw_blendmv64qi; ---> TARGET_AVX512BW needed
3684 break;
3685 case E_V32HImode:
3686 gen = gen_avx512bw_blendmv32hi; --> TARGET_AVX512BW needed
3687 break;
3688 case E_V16SImode:
3689 gen = gen_avx512f_blendmv16si;
3690 break;
3691 case E_V8DImode:
3692 gen = gen_avx512f_blendmv8di;
3693 break;
3694 case E_V8DFmode:
> faster, smaller and eventually even easier during expansion?
>
> + gcc_assert (ix86_expand_vector_init_duplicate (false, mode, valv, val));
> + gcc_assert (ix86_expand_vector_init_duplicate (false, cmp_mode,
> idxv, idx_tmp));
>
> side-effects in gcc_assert is considered bad style, use
>
> ok = ix86_expand_vector_init_duplicate (false, mode, valv, val);
> gcc_assert (ok);
>
> + vec[5] = constv;
> + ix86_expand_int_vcond (vec);
>
> this also returns a bool you probably should assert true.
>
Yes, will change.
> Otherwise thanks for tackling this.
>
> Richard.
>
> > gcc/ChangeLog:
> >
> > PR target/97194
> > * config/i386/i386-expand.c (ix86_expand_vector_set_var): New
> > function.
> > * config/i386/i386-protos.h (ix86_expand_vector_set_var): New Decl.
> > * config/i386/predicates.md (vec_setm_operand): New predicate,
> > true for const_int_operand or register_operand under TARGET_AVX2.
> > * config/i386/sse.md (vec_set<mode>): Support both constant
> > and variable index vec_set.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * gcc.target/i386/avx2-vec-set-1.c: New test.
> > * gcc.target/i386/avx2-vec-set-2.c: New test.
> > * gcc.target/i386/avx512bw-vec-set-1.c: New test.
> > * gcc.target/i386/avx512bw-vec-set-2.c: New test.
> > * gcc.target/i386/avx512f-vec-set-2.c: New test.
> > * gcc.target/i386/avx512vl-vec-set-2.c: New test.
> >
> > --
> > BR,
> > Hongtao
--
BR,
Hongtao
