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tree-optimization/96698 - fix ICE when vectorizing nested cycles

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This fixes vectorized PHI latch edge updating and delay it until
all of the loop is code generated to deal with the case that the
latch def is a PHI in the same block.

2020-08-26  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/96698
	* tree-vectorizer.h (loop_vec_info::reduc_latch_defs): New.
	(loop_vec_info::reduc_latch_slp_defs): Likewise.
	* tree-vect-stmts.c (vect_transform_stmt): Only record
	stmts to update PHI latches from, perform the update ...
	* tree-vect-loop.c (vect_transform_loop): ... here after
	vectorizing those PHIs.
	(info_for_reduction): Properly handle non-reduction PHIs.

	* gcc.dg/vect/pr96698.c: New testcase.
This commit is contained in:
Richard Biener 2020-08-26 15:12:17 +02:00
parent 3eefb302d2
commit 2130efe6ac
4 changed files with 63 additions and 25 deletions
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19
gcc/testsuite/gcc.dg/vect/pr96698.c Normal file
View file

@ -0,0 +1,19 @@
/* { dg-do compile } */
void test(int a, int* i)
{
for (; a < 5; ++a)
{
int b = 0;
int c = 0;
for (; b != -11; b--)
for (int d = 0; d ==0; d++)
{
*i += c & a;
c = b;
}
}
}
/* We should be able to vectorize the inner cycle. */
/* { dg-final { scan-tree-dump "OUTER LOOP VECTORIZED" "vect" { target vect_int } } } */

35
gcc/tree-vect-loop.c
View file

@ -4646,7 +4646,8 @@ info_for_reduction (vec_info *vinfo, stmt_vec_info stmt_info)
{
stmt_info = vect_orig_stmt (stmt_info);
gcc_assert (STMT_VINFO_REDUC_DEF (stmt_info));
if (!is_a <gphi *> (stmt_info->stmt))
if (!is_a <gphi *> (stmt_info->stmt)
|| !VECTORIZABLE_CYCLE_DEF (STMT_VINFO_DEF_TYPE (stmt_info)))
stmt_info = STMT_VINFO_REDUC_DEF (stmt_info);
gphi *phi = as_a <gphi *> (stmt_info->stmt);
if (STMT_VINFO_DEF_TYPE (stmt_info) == vect_double_reduction_def)
@ -9031,6 +9032,38 @@ vect_transform_loop (loop_vec_info loop_vinfo, gimple *loop_vectorized_call)
}
}
/* Fill in backedge defs of reductions. */
for (unsigned i = 0; i < loop_vinfo->reduc_latch_defs.length (); ++i)
{
stmt_vec_info stmt_info = loop_vinfo->reduc_latch_defs[i];
stmt_vec_info orig_stmt_info = vect_orig_stmt (stmt_info);
vec<gimple *> &phi_info
= STMT_VINFO_VEC_STMTS (STMT_VINFO_REDUC_DEF (orig_stmt_info));
vec<gimple *> &vec_stmt
= STMT_VINFO_VEC_STMTS (stmt_info);
gcc_assert (phi_info.length () == vec_stmt.length ());
gphi *phi
= dyn_cast <gphi *> (STMT_VINFO_REDUC_DEF (orig_stmt_info)->stmt);
edge e = loop_latch_edge (gimple_bb (phi_info[0])->loop_father);
for (unsigned j = 0; j < phi_info.length (); ++j)
add_phi_arg (as_a <gphi *> (phi_info[j]),
gimple_get_lhs (vec_stmt[j]), e,
gimple_phi_arg_location (phi, e->dest_idx));
}
for (unsigned i = 0; i < loop_vinfo->reduc_latch_slp_defs.length (); ++i)
{
slp_tree slp_node = loop_vinfo->reduc_latch_slp_defs[i].first;
slp_tree phi_node = loop_vinfo->reduc_latch_slp_defs[i].second;
gphi *phi = as_a <gphi *> (SLP_TREE_SCALAR_STMTS (phi_node)[0]->stmt);
e = loop_latch_edge (gimple_bb (phi)->loop_father);
gcc_assert (SLP_TREE_VEC_STMTS (phi_node).length ()
== SLP_TREE_VEC_STMTS (slp_node).length ());
for (unsigned j = 0; j < SLP_TREE_VEC_STMTS (phi_node).length (); ++j)
add_phi_arg (as_a <gphi *> (SLP_TREE_VEC_STMTS (phi_node)[j]),
vect_get_slp_vect_def (slp_node, j),
e, gimple_phi_arg_location (phi, e->dest_idx));
}
/* Stub out scalar statements that must not survive vectorization.
Doing this here helps with grouped statements, or statements that
are involved in patterns. */

29
gcc/tree-vect-stmts.c
View file

@ -10920,8 +10920,8 @@ vect_transform_stmt (vec_info *vinfo,
if (STMT_VINFO_TYPE (stmt_info) == store_vec_info_type)
return is_store;
/* If this stmt defines a value used on a backedge, update the
vectorized PHIs. */
/* If this stmt defines a value used on a backedge, record it so
we can update the vectorized PHIs later. */
stmt_vec_info orig_stmt_info = vect_orig_stmt (stmt_info);
stmt_vec_info reduc_info;
if (STMT_VINFO_REDUC_DEF (orig_stmt_info)
@ -10940,30 +10940,11 @@ vect_transform_stmt (vec_info *vinfo,
&& (e = loop_latch_edge (gimple_bb (phi)->loop_father))
&& (PHI_ARG_DEF_FROM_EDGE (phi, e)
== gimple_get_lhs (orig_stmt_info->stmt)))
{
vec<gimple *> &phi_info
= STMT_VINFO_VEC_STMTS (STMT_VINFO_REDUC_DEF (orig_stmt_info));
vec<gimple *> &vec_stmt
= STMT_VINFO_VEC_STMTS (stmt_info);
gcc_assert (phi_info.length () == vec_stmt.length ());
for (unsigned i = 0; i < phi_info.length (); ++i)
add_phi_arg (as_a <gphi *> (phi_info[i]),
gimple_get_lhs (vec_stmt[i]), e,
gimple_phi_arg_location (phi, e->dest_idx));
}
as_a <loop_vec_info> (vinfo)->reduc_latch_defs.safe_push (stmt_info);
else if (slp_node
&& slp_node != slp_node_instance->reduc_phis)
{
slp_tree phi_node = slp_node_instance->reduc_phis;
gphi *phi = as_a <gphi *> (SLP_TREE_SCALAR_STMTS (phi_node)[0]->stmt);
e = loop_latch_edge (gimple_bb (phi)->loop_father);
gcc_assert (SLP_TREE_VEC_STMTS (phi_node).length ()
== SLP_TREE_VEC_STMTS (slp_node).length ());
for (unsigned i = 0; i < SLP_TREE_VEC_STMTS (phi_node).length (); ++i)
add_phi_arg (as_a <gphi *> (SLP_TREE_VEC_STMTS (phi_node)[i]),
vect_get_slp_vect_def (slp_node, i),
e, gimple_phi_arg_location (phi, e->dest_idx));
}
as_a <loop_vec_info> (vinfo)->reduc_latch_slp_defs.safe_push
(std::make_pair (slp_node, slp_node_instance->reduc_phis));
}
/* Handle stmts whose DEF is used outside the loop-nest that is

5
gcc/tree-vectorizer.h
View file

@ -627,6 +627,11 @@ public:
stmt in the chain. */
auto_vec<stmt_vec_info> reduction_chains;
/* The vectorized stmts defining the latch values of the reduction
they are involved with. */
auto_vec<stmt_vec_info> reduc_latch_defs;
auto_vec<std::pair<slp_tree, slp_tree> > reduc_latch_slp_defs;
/* Cost vector for a single scalar iteration. */
auto_vec<stmt_info_for_cost> scalar_cost_vec;