On Thu, Nov 10, 2022 at 3:27 AM Hongyu Wang <wwwhhhyyy...@gmail.com> wrote:
>
> Hi Prathamesh and Richard,
>
> Thanks for the review and nice suggestions!
>
> > > I guess the transform should work as long as mask is same for both
> > > vectors even if it's
> > > not constant ?
> >
> > Yes, please change accordingly (and maybe push separately).
> >
>
> Removed VECTOR_CST for integer ops.
>
> > > If this transform is meant only for VLS vectors, I guess you should
> > > bail out if TYPE_VECTOR_SUBPARTS is not constant,
> > > otherwise it will crash for VLA vectors.
> >
> > I suppose it's difficult to create a VLA permute that covers all elements
> > and that is not trivial though. But indeed add ().is_constant to the
> > VECTOR_FLOAT_TYPE_P guard.
>
> Added.
>
> > Meh, that's quadratic! I suggest to check .encoding
> > ().encoded_full_vector_p ()
> > (as said I can't think of a non-full encoding that isn't trivial
> > but covers all elements) and then simply .qsort () the vector_builder
> > (it derives
> > from vec<>) so the scan is O(n log n).
>
> The .qsort () approach requires an extra cmp_func that IMO would not
> be feasible to be implemented in match.pd (I suppose lambda function
> would not be a good idea either).
> Another solution would be using hash_set but it does not work here for
> int64_t or poly_int64 type.
> So I kept current O(n^2) simple code here, and I suppose usually the
> permutation indices would be a small number even for O(n^2)
> complexity.
Well, with AVX512 v64qi that's 64*64 == 4096 cases to check. I think
a lambda function is fine to use. The alternative (used by the vectorizer
in some places) is to use sth like
auto_sbitmap seen (nelts);
for (i = 0; i < nelts; i++)
{
if (!bitmap_set_bit (seen, i))
break;
count++;
}
full_perm_p = count == nelts;
I'll note that you should still check .encoding ().encoded_full_vector_p ()
and only bother to check that case, that's a very simple check.
>
> Attached updated patch.
>
> Richard Biener via Gcc-patches <gcc-patches@gcc.gnu.org> 于2022年11月8日周二
> 22:38写道：
>
>
> >
> > On Fri, Nov 4, 2022 at 7:44 AM Prathamesh Kulkarni via Gcc-patches
> > <gcc-patches@gcc.gnu.org> wrote:
> > >
> > > On Fri, 4 Nov 2022 at 05:36, Hongyu Wang via Gcc-patches
> > > <gcc-patches@gcc.gnu.org> wrote:
> > > >
> > > > Hi,
> > > >
> > > > This is a follow-up patch for PR98167
> > > >
> > > > The sequence
> > > > c1 = VEC_PERM_EXPR (a, a, mask)
> > > > c2 = VEC_PERM_EXPR (b, b, mask)
> > > > c3 = c1 op c2
> > > > can be optimized to
> > > > c = a op b
> > > > c3 = VEC_PERM_EXPR (c, c, mask)
> > > > for all integer vector operation, and float operation with
> > > > full permutation.
> > > >
> > > > Bootstrapped & regrtested on x86_64-pc-linux-gnu.
> > > >
> > > > Ok for trunk?
> > > >
> > > > gcc/ChangeLog:
> > > >
> > > > PR target/98167
> > > > * match.pd: New perm + vector op patterns for int and fp vector.
> > > >
> > > > gcc/testsuite/ChangeLog:
> > > >
> > > > PR target/98167
> > > > * gcc.target/i386/pr98167.c: New test.
> > > > ---
> > > > gcc/match.pd | 49 +++++++++++++++++++++++++
> > > > gcc/testsuite/gcc.target/i386/pr98167.c | 44 ++++++++++++++++++++++
> > > > 2 files changed, 93 insertions(+)
> > > > create mode 100644 gcc/testsuite/gcc.target/i386/pr98167.c
> > > >
> > > > diff --git a/gcc/match.pd b/gcc/match.pd
> > > > index 194ba8f5188..b85ad34f609 100644
> > > > --- a/gcc/match.pd
> > > > +++ b/gcc/match.pd
> > > > @@ -8189,3 +8189,52 @@ and,
> > > > (bit_and (negate @0) integer_onep@1)
> > > > (if (!TYPE_OVERFLOW_SANITIZED (type))
> > > > (bit_and @0 @1)))
> > > > +
> > > > +/* Optimize
> > > > + c1 = VEC_PERM_EXPR (a, a, mask)
> > > > + c2 = VEC_PERM_EXPR (b, b, mask)
> > > > + c3 = c1 op c2
> > > > + -->
> > > > + c = a op b
> > > > + c3 = VEC_PERM_EXPR (c, c, mask)
> > > > + For all integer non-div operations. */
> > > > +(for op (plus minus mult bit_and bit_ior bit_xor
> > > > + lshift rshift)
> > > > + (simplify
> > > > + (op (vec_perm @0 @0 VECTOR_CST@2) (vec_perm @1 @1 VECTOR_CST@2))
> > > > + (if (VECTOR_INTEGER_TYPE_P (type))
> > > > + (vec_perm (op @0 @1) (op @0 @1) @2))))
> > > Just wondering, why should mask be CST here ?
> > > I guess the transform should work as long as mask is same for both
> > > vectors even if it's
> > > not constant ?
> >
> > Yes, please change accordingly (and maybe push separately).
> >
> > > > +
> > > > +/* Similar for float arithmetic when permutation constant covers
> > > > + all vector elements. */
> > > > +(for op (plus minus mult)
> > > > + (simplify
> > > > + (op (vec_perm @0 @0 VECTOR_CST@2) (vec_perm @1 @1 VECTOR_CST@2))
> > > > + (if (VECTOR_FLOAT_TYPE_P (type))
> > > > + (with
> > > > + {
> > > > + tree perm_cst = @2;
> > > > + vec_perm_builder builder;
> > > > + bool full_perm_p = false;
> > > > + if (tree_to_vec_perm_builder (&builder, perm_cst))
> > > > + {
> > > > + /* Create a vec_perm_indices for the integer vector. */
> > > > + int nelts = TYPE_VECTOR_SUBPARTS (type).to_constant ();
> > > If this transform is meant only for VLS vectors, I guess you should
> > > bail out if TYPE_VECTOR_SUBPARTS is not constant,
> > > otherwise it will crash for VLA vectors.
> >
> > I suppose it's difficult to create a VLA permute that covers all elements
> > and that is not trivial though. But indeed add ().is_constant to the
> > VECTOR_FLOAT_TYPE_P guard.
> >
> > >
> > > Thanks,
> > > Prathamesh
> > > > + vec_perm_indices sel (builder, 1, nelts);
> > > > +
> > > > + /* Check if perm indices covers all vector elements. */
> > > > + int count = 0, i, j;
> > > > + for (i = 0; i < nelts; i++)
> > > > + for (j = 0; j < nelts; j++)
> >
> > Meh, that's quadratic! I suggest to check .encoding
> > ().encoded_full_vector_p ()
> > (as said I can't think of a non-full encoding that isn't trivial
> > but covers all elements) and then simply .qsort () the vector_builder
> > (it derives
> > from vec<>) so the scan is O(n log n).
> >
> > Maybe Richard has a better idea here though.
> >
> > Otherwise looks OK, though with these kind of (* (op ..) (op ..)) patterns
> > it's
> > always that they explode the match decision tree, we'd ideally have a way to
> > match those with (op ..) (op ..) first to be able to share more of the
> > matching
> > code. That said, match.pd is a less than ideal place for these (but mostly
> > because of the way we code generate *-match.cc)
> >
> > Richard.
> >
> > > > + {
> > > > + if (sel[j].to_constant () == i)
> > > > + {
> > > > + count++;
> > > > + break;
> > > > + }
> > > > + }
> > > > + full_perm_p = count == nelts;
> > > > + }
> > > > + }
> > > > + (if (full_perm_p)
> > > > + (vec_perm (op @0 @1) (op @0 @1) @2))))))
> > > > diff --git a/gcc/testsuite/gcc.target/i386/pr98167.c
> > > > b/gcc/testsuite/gcc.target/i386/pr98167.c
> > > > new file mode 100644
> > > > index 00000000000..40e0ac11332
> > > > --- /dev/null
> > > > +++ b/gcc/testsuite/gcc.target/i386/pr98167.c
> > > > @@ -0,0 +1,44 @@
> > > > +/* PR target/98167 */
> > > > +/* { dg-do compile } */
> > > > +/* { dg-options "-O2 -mavx2" } */
> > > > +
> > > > +/* { dg-final { scan-assembler-times "vpshufd\t" 8 } } */
> > > > +/* { dg-final { scan-assembler-times "vpermilps\t" 3 } } */
> > > > +
> > > > +#define VEC_PERM_4 \
> > > > + 2, 3, 1, 0
> > > > +#define VEC_PERM_8 \
> > > > + 4, 5, 6, 7, 3, 2, 1, 0
> > > > +#define VEC_PERM_16 \
> > > > + 8, 9, 10, 11, 12, 13, 14, 15, 7, 6, 5, 4, 3, 2, 1, 0
> > > > +
> > > > +#define TYPE_PERM_OP(type, size, op, name) \
> > > > + typedef type v##size##s##type __attribute__ ((vector_size(4*size)));
> > > > \
> > > > + v##size##s##type type##foo##size##i_##name (v##size##s##type a, \
> > > > + v##size##s##type b) \
> > > > + { \
> > > > + v##size##s##type a1 = __builtin_shufflevector (a, a, \
> > > > + VEC_PERM_##size); \
> > > > + v##size##s##type b1 = __builtin_shufflevector (b, b, \
> > > > + VEC_PERM_##size); \
> > > > + return a1 op b1; \
> > > > + }
> > > > +
> > > > +#define INT_PERMS(op, name) \
> > > > + TYPE_PERM_OP (int, 4, op, name) \
> > > > +
> > > > +#define FP_PERMS(op, name) \
> > > > + TYPE_PERM_OP (float, 4, op, name) \
> > > > +
> > > > +INT_PERMS (+, add)
> > > > +INT_PERMS (-, sub)
> > > > +INT_PERMS (*, mul)
> > > > +INT_PERMS (|, ior)
> > > > +INT_PERMS (^, xor)
> > > > +INT_PERMS (&, and)
> > > > +INT_PERMS (<<, shl)
> > > > +INT_PERMS (>>, shr)
> > > > +FP_PERMS (+, add)
> > > > +FP_PERMS (-, sub)
> > > > +FP_PERMS (*, mul)
> > > > +
> > > > --
> > > > 2.18.1
> > > >
