Hi,
As PR91790 exposed, when we have one slp node whose first_stmt_info_for_drptr
is different from first_stmt_info, it's possible that the first_stmt DR isn't
initialized yet before stmt SLP_TREE_SCALAR_STMTS[0] of slp node. So we
shouldn't use first_stmt_info for vect_setup_realignment, instead we can use
the one based on first_stmt_info_for_drptr DR with additional adjustment by
bumping the distance from first_stmt DR.
Bootstrapped and tested on powerpc64le-linux-gnu (P8LE) and
ppc64-redhat-linux (P7BE) which need to use realign_load.
Is it ok for trunk? and backport to GCC 9 after some burn-in time?
BR,
Kewen
----
gcc/ChangeLog
2019-11-27 Kewen Lin <li...@gcc.gnu.org>
PR tree-optimization/91790
* gcc/tree-vect-stmts.c (vectorizable_load): Use the adjusted DR for
vect_setup_realignment when first_stmt_info is different from
first_stmt_info_for_drptr.
diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
index fb669cd..422947b 100644
--- a/gcc/tree-vect-stmts.c
+++ b/gcc/tree-vect-stmts.c
@@ -9186,18 +9186,27 @@ vectorizable_load (stmt_vec_info stmt_info,
gimple_stmt_iterator *gsi,
compute_in_loop = true;
}
+ bool diff_first_stmt_info
+ = first_stmt_info_for_drptr && first_stmt_info !=
first_stmt_info_for_drptr;
+
if ((alignment_support_scheme == dr_explicit_realign_optimized
|| alignment_support_scheme == dr_explicit_realign)
&& !compute_in_loop)
{
- msq = vect_setup_realignment (first_stmt_info, gsi, &realignment_token,
- alignment_support_scheme, NULL_TREE,
- &at_loop);
+ /* If we have different first_stmt_info, we can't set up realignment
+ here, since we can't guarantee first_stmt_info DR has been
+ initialized yet, use first_stmt_info_for_drptr DR by bumping the
+ distance from first_stmt_info DR instead as below. */
+ if (!diff_first_stmt_info)
+ msq = vect_setup_realignment (first_stmt_info, gsi, &realignment_token,
+ alignment_support_scheme, NULL_TREE,
+ &at_loop);
if (alignment_support_scheme == dr_explicit_realign_optimized)
{
phi = as_a <gphi *> (SSA_NAME_DEF_STMT (msq));
byte_offset = size_binop (MINUS_EXPR, TYPE_SIZE_UNIT (vectype),
size_one_node);
+ gcc_assert (!first_stmt_info_for_drptr);
}
}
else
@@ -9253,8 +9262,7 @@ vectorizable_load (stmt_vec_info stmt_info,
gimple_stmt_iterator *gsi,
dataref_ptr = unshare_expr (DR_BASE_ADDRESS (first_dr_info->dr));
dataref_offset = build_int_cst (ref_type, 0);
}
- else if (first_stmt_info_for_drptr
- && first_stmt_info != first_stmt_info_for_drptr)
+ else if (diff_first_stmt_info)
{
dataref_ptr
= vect_create_data_ref_ptr (first_stmt_info_for_drptr,
@@ -9271,6 +9279,14 @@ vectorizable_load (stmt_vec_info stmt_info,
gimple_stmt_iterator *gsi,
DR_INIT (ptrdr)));
dataref_ptr = bump_vector_ptr (dataref_ptr, ptr_incr, gsi,
stmt_info, diff);
+ if (alignment_support_scheme == dr_explicit_realign)
+ {
+ msq = vect_setup_realignment (first_stmt_info_for_drptr, gsi,
+ &realignment_token,
+ alignment_support_scheme,
+ dataref_ptr, &at_loop);
+ gcc_assert (!compute_in_loop);
+ }
}
else if (STMT_VINFO_GATHER_SCATTER_P (stmt_info))
vect_get_gather_scatter_ops (loop, stmt_info, &gs_info,
