On Mon, Oct 19, 2020 at 5:55 PM Richard Biener
<richard.guent...@gmail.com> wrote:
>
> On Mon, Oct 19, 2020 at 11:37 AM Hongtao Liu <crazy...@gmail.com> wrote:
> >
> > 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?
>
> Oh, I see. Guess two back-to-back vpternlog could emulate
Yes, we can have something like vpternlogd %zmm0, %zmm1, %zmm2, 0xD8,
but since we don't have 512-bits bytes/word broadcast instruction,
It would need 2 broadcast and 1 vec_concat to get 1 512-bits vector.
it wouldn't save many instructions compared to my version(as below).
---
leal -16(%rsi), %eax
vmovd %edi, %xmm2
vmovdqa .LC0(%rip), %ymm4
vextracti64x4 $0x1, %zmm0, %ymm3
vmovd %eax, %xmm1
vpbroadcastw %xmm2, %ymm2
vpbroadcastw %xmm1, %ymm1
vpcmpeqw %ymm4, %ymm1, %ymm1
vpblendvb %ymm1, %ymm2, %ymm3, %ymm3
vmovd %esi, %xmm1
vpbroadcastw %xmm1, %ymm1
vpcmpeqw %ymm4, %ymm1, %ymm1
vpblendvb %ymm1, %ymm2, %ymm0, %ymm0
vinserti64x4 $0x1, %ymm3, %zmm0, %zmm0
---
> the blend? Not sure if important - I recall only knl didn't have bw?
>
Yes, after(including) SKX, all avx512 targets will support AVX512BW.
And i don't think performance for V32HI/V64QI without AVX512BW is important.
> > 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
--
BR,
Hongtao
