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
> >
