On Fri, Apr 9, 2021 at 10:28 AM Richard Biener <rguent...@suse.de> wrote:
>
> We can use TBAA even when we have a DR, do so. For the testcase
> that means fully vectorizing it instead of only vectorizing
> the first store group resulting in suboptimal code.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu, queued for stage1.
g:700e542971251b11623cce877075567815f72965
> 2021-04-09 Richard Biener <rguent...@suse.de>
>
> PR tree-optimization/99971
> * tree-vect-data-refs.c (vect_slp_analyze_node_dependences):
> Always use TBAA for loads.
>
> * g++.dg/vect/slp-pr99971.cc: New testcase.
> ---
> gcc/testsuite/g++.dg/vect/slp-pr99971.cc | 36 ++++++++++++++++++++++++
> gcc/tree-vect-data-refs.c | 18 +++++++-----
> 2 files changed, 47 insertions(+), 7 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/vect/slp-pr99971.cc
>
> diff --git a/gcc/testsuite/g++.dg/vect/slp-pr99971.cc
> b/gcc/testsuite/g++.dg/vect/slp-pr99971.cc
> new file mode 100644
> index 00000000000..bec6418d4e8
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/vect/slp-pr99971.cc
> @@ -0,0 +1,36 @@
> +// { dg-do compile }
> +// { dg-require-effective-target vect_int }
> +
> +struct A
> +{
> + unsigned int a, b, c, d;
> +
> + A& operator+= (A const& that)
> + {
> + a += that.a;
> + b += that.b;
> + c += that.c;
> + d += that.d;
> + return *this;
> + }
> +
> + A& operator-= (A const& that)
> + {
> + a -= that.a;
> + b -= that.b;
> + c -= that.c;
> + d -= that.d;
> + return *this;
> + }
> +};
> +
> +void test(A& x, A const& y1, A const& y2)
> +{
> + x += y1;
> + x -= y2;
> +}
> +
> +// We want to SLP vectorize a single connected SLP subgraph with two
> instances
> +// { dg-final { scan-tree-dump-not "removing SLP instance" "slp2" } }
> +// { dg-final { scan-tree-dump-times "SLPing BB part" 1 "slp2" } }
> +// { dg-final { scan-tree-dump-times "Vectorizing SLP" 2 "slp2" } }
> diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c
> index ee266ba62a8..6ea5e3a3eda 100644
> --- a/gcc/tree-vect-data-refs.c
> +++ b/gcc/tree-vect-data-refs.c
> @@ -780,16 +780,20 @@ vect_slp_analyze_node_dependences (vec_info *vinfo,
> slp_tree node,
> stmt we have to resort to the alias oracle. */
> stmt_vec_info stmt_info = vinfo->lookup_stmt (stmt);
> data_reference *dr_b = STMT_VINFO_DATA_REF (stmt_info);
> - if (!dr_b)
> +
> + /* We are hoisting a load - this means we can use
> + TBAA for disambiguation. */
> + if (!ref_initialized_p)
> + ao_ref_init (&ref, DR_REF (dr_a));
> + if (stmt_may_clobber_ref_p_1 (stmt, &ref, true))
> {
> - /* We are hoisting a load - this means we can use
> - TBAA for disambiguation. */
> - if (!ref_initialized_p)
> - ao_ref_init (&ref, DR_REF (dr_a));
> - if (stmt_may_clobber_ref_p_1 (stmt, &ref, true))
> + if (!dr_b)
> return false;
> - continue;
> + /* Resort to dependence checking below. */
> }
> + else
> + /* No dependence. */
> + continue;
>
> bool dependent = false;
> /* If we run into a store of this same instance (we've just
> --
> 2.26.2
