On Thu, 7 Dec 2017, Bin.Cheng wrote:
> On Wed, Dec 6, 2017 at 1:29 PM, Richard Biener <rguent...@suse.de> wrote:
> >
> > The following fixes a vectorization issue that appears when trying
> > to vectorize the bwaves mat_times_vec kernel after interchange was
> > performed by the interchange pass. That interchange inserts the
> > following code for the former reduction created by LIM store-motion:
> I do observe more cases are vectorized by this patch on AArch64.
> Still want to find a way not generating the cond_expr, but for the moment
> I will have another patch make interchange even more conservative for
> small cases. In which the new cmp/select instructions do cost a lot against
> the small loop body.
Yeah. I thought about what it takes to avoid the conditional - basically
we'd need to turn the init value to a (non-nested) loop that we'd need
to insert on the preheader of the outer loop.
Richard.
> Thanks,
> bin
> >
> > <bb 13> [local count: 161061274]:
> > # m_58 = PHI <1(10), m_84(20)>
> > ...
> > <bb 14> [local count: 912680551]:
> > # l_35 = PHI <1(13), l_57(21)>
> > ...
> > y__I_lsm.113_140 = *y_139(D)[_31];
> > y__I_lsm.113_94 = m_58 != 1 ? y__I_lsm.113_140 : 0.0;
> > ...
> > *y_139(D)[_31] = _101;
> >
> >
> > so we have a COND_EXPR with a test on an integer IV m_58 with
> > double values. Note that the m_58 != 1 condition is invariant
> > in the l loop.
> >
> > Currently we vectorize this condition using V8SImode vectors
> > causing a vectorization factor of 8 and thus forcing the scalar
> > path for the bwaves case (the loops have an iteration count of 5).
> >
> > The following patch makes the vectorizer handle invariant conditions
> > in the first place and second handle widening of operands of invariant
> > conditions transparently (the promotion will happen on the invariant
> > scalars). This makes it possible to use a vectorization factor of 4,
> > reducing the bwaves runtime from 208s before interchange
> > (via 190s after interchange) to 172s after interchange and vectorization
> > with AVX256 (on a Haswell machine).
> >
> > For the vectorizable_condition part to work I need to avoid
> > pulling apart the condition from the COND_EXPR during pattern
> > detection.
> >
> > Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
> >
> > Richard.
> >
> > 2017-12-06 Richard Biener <rguent...@suse.de>
> >
> > PR tree-optimization/81303
> > * tree-vect-stmts.c (vect_is_simple_cond): For invariant
> > conditions try to create a comparison vector type matching
> > the data vector type.
> > (vectorizable_condition): Adjust.
> > * tree-vect-patterns.c (vect_recog_mask_conversion_pattern):
> > Leave invariant conditions alone in case we can vectorize those.
> >
> > * gcc.target/i386/vectorize9.c: New testcase.
> > * gcc.target/i386/vectorize10.c: New testcase.
> >
> > Index: gcc/tree-vect-stmts.c
> > ===================================================================
> > --- gcc/tree-vect-stmts.c (revision 255438)
> > +++ gcc/tree-vect-stmts.c (working copy)
> > @@ -7792,7 +7792,8 @@ vectorizable_load (gimple *stmt, gimple_
> >
> > static bool
> > vect_is_simple_cond (tree cond, vec_info *vinfo,
> > - tree *comp_vectype, enum vect_def_type *dts)
> > + tree *comp_vectype, enum vect_def_type *dts,
> > + tree vectype)
> > {
> > tree lhs, rhs;
> > tree vectype1 = NULL_TREE, vectype2 = NULL_TREE;
> > @@ -7845,6 +7846,20 @@ vect_is_simple_cond (tree cond, vec_info
> > return false;
> >
> > *comp_vectype = vectype1 ? vectype1 : vectype2;
> > + /* Invariant comparison. */
> > + if (! *comp_vectype)
> > + {
> > + tree scalar_type = TREE_TYPE (lhs);
> > + /* If we can widen the comparison to match vectype do so. */
> > + if (INTEGRAL_TYPE_P (scalar_type)
> > + && tree_int_cst_lt (TYPE_SIZE (scalar_type),
> > + TYPE_SIZE (TREE_TYPE (vectype))))
> > + scalar_type = build_nonstandard_integer_type
> > + (tree_to_uhwi (TYPE_SIZE (TREE_TYPE (vectype))),
> > + TYPE_UNSIGNED (scalar_type));
> > + *comp_vectype = get_vectype_for_scalar_type (scalar_type);
> > + }
> > +
> > return true;
> > }
> >
> > @@ -7942,7 +7957,7 @@ vectorizable_condition (gimple *stmt, gi
> > else_clause = gimple_assign_rhs3 (stmt);
> >
> > if (!vect_is_simple_cond (cond_expr, stmt_info->vinfo,
> > - &comp_vectype, &dts[0])
> > + &comp_vectype, &dts[0], vectype)
> > || !comp_vectype)
> > return false;
> >
> > Index: gcc/tree-vect-patterns.c
> > ===================================================================
> > --- gcc/tree-vect-patterns.c (revision 255438)
> > +++ gcc/tree-vect-patterns.c (working copy)
> > @@ -3976,6 +3976,32 @@ vect_recog_mask_conversion_pattern (vec<
> > || TYPE_VECTOR_SUBPARTS (vectype1) == TYPE_VECTOR_SUBPARTS
> > (vectype2))
> > return NULL;
> >
> > + /* If rhs1 is invariant and we can promote it leave the COND_EXPR
> > + in place, we can handle it in vectorizable_condition. This avoids
> > + unnecessary promotion stmts and increased vectorization factor. */
> > + if (COMPARISON_CLASS_P (rhs1)
> > + && INTEGRAL_TYPE_P (rhs1_type)
> > + && TYPE_VECTOR_SUBPARTS (vectype1) < TYPE_VECTOR_SUBPARTS
> > (vectype2))
> > + {
> > + gimple *dummy;
> > + enum vect_def_type dt;
> > + if (vect_is_simple_use (TREE_OPERAND (rhs1, 0), stmt_vinfo->vinfo,
> > + &dummy, &dt)
> > + && dt == vect_external_def
> > + && vect_is_simple_use (TREE_OPERAND (rhs1, 1),
> > stmt_vinfo->vinfo,
> > + &dummy, &dt)
> > + && (dt == vect_external_def
> > + || dt == vect_constant_def))
> > + {
> > + tree wide_scalar_type = build_nonstandard_integer_type
> > + (tree_to_uhwi (TYPE_SIZE (TREE_TYPE (vectype1))),
> > + TYPE_UNSIGNED (rhs1_type));
> > + tree vectype3 = get_vectype_for_scalar_type
> > (wide_scalar_type);
> > + if (expand_vec_cond_expr_p (vectype1, vectype3, TREE_CODE
> > (rhs1)))
> > + return NULL;
> > + }
> > + }
> > +
> > /* If rhs1 is a comparison we need to move it into a
> > separate statement. */
> > if (TREE_CODE (rhs1) != SSA_NAME)
> > Index: gcc/testsuite/gcc.target/i386/vectorize9.c
> > ===================================================================
> > --- gcc/testsuite/gcc.target/i386/vectorize9.c (nonexistent)
> > +++ gcc/testsuite/gcc.target/i386/vectorize9.c (working copy)
> > @@ -0,0 +1,16 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-O -ftree-loop-vectorize -fdump-tree-vect-details
> > -fno-tree-loop-im -mavx2 -mprefer-vector-width=256" } */
> > +
> > +double x[1024][1024], red[1024];
> > +void foo (void)
> > +{
> > + for (int i = 0; i < 1024; ++i)
> > + for (int j = 0; j < 1024; ++j)
> > + {
> > + double v = i == 0 ? 0.0 : red[j];
> > + v = v + x[i][j];
> > + red[j] = v;
> > + }
> > +}
> > +
> > +/* { dg-final { scan-tree-dump "vectorization factor = 4" "vect" } } */
> > Index: gcc/testsuite/gcc.target/i386/vectorize10.c
> > ===================================================================
> > --- gcc/testsuite/gcc.target/i386/vectorize10.c (nonexistent)
> > +++ gcc/testsuite/gcc.target/i386/vectorize10.c (working copy)
> > @@ -0,0 +1,16 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-O -ftree-loop-vectorize -fdump-tree-vect-details
> > -fno-tree-loop-im -msse2 -mno-avx" } */
> > +
> > +double x[1024][1024], red[1024];
> > +void foo (void)
> > +{
> > + for (int i = 0; i < 1024; ++i)
> > + for (int j = 0; j < 1024; ++j)
> > + {
> > + double v = i == 0 ? 0.0 : red[j];
> > + v = v + x[i][j];
> > + red[j] = v;
> > + }
> > +}
> > +
> > +/* { dg-final { scan-tree-dump "vectorized 1 loops" "vect" } } */
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
