https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117140
--- Comment #7 from Tamar Christina <tnfchris at gcc dot gnu.org> ---
For this statement somehow the location of the gsi ends up having
first == last, so gsi_insert_before just silently ignores the insert.
The ICE happens because for this one BB, no vector statement is ever emitted to
the BB.
Reverting to the original code I had
diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
index 8727246c27a..c028594e18b 100644
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -11128,7 +11128,8 @@ vectorize_slp_instance_root_stmt (vec_info *vinfo,
slp_tree node, slp_instance i
can't support lane > 1 at this time. */
gcc_assert (instance->root_stmts.length () == 1);
auto root_stmt_info = instance->root_stmts[0];
- auto last_stmt = STMT_VINFO_STMT (root_stmt_info);
+ auto last_stmt = vect_find_first_scalar_stmt_in_slp (node)->stmt;
gimple_stmt_iterator rgsi = gsi_for_stmt (last_stmt);
gimple *vec_stmt = NULL;
gcc_assert (!SLP_TREE_VEC_DEFS (node).is_empty ());
works correctly, but I'd like to figure out why. So looking into that first.
