https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98849
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
For #c2 I've tried:
--- gcc/tree-vect-generic.c.jj 2021-01-04 10:25:38.289239984 +0100
+++ gcc/tree-vect-generic.c 2021-01-27 13:53:28.457752505 +0100
@@ -2147,16 +2147,21 @@ expand_vector_operations_1 (gimple_stmt_
|| code == LROTATE_EXPR
|| code == RROTATE_EXPR)
{
- optab opv;
+ optab opv = optab_for_tree_code (code, type, optab_vector);
/* Check whether we have vector <op> {x,x,x,x} where x
could be a scalar variable or a constant. Transform
- vector <op> {x,x,x,x} ==> vector <op> scalar. */
+ vector <op> {x,x,x,x} ==> vector <op> scalar, unless
+ the backend only supports vector <op> by vector and not
+ vecot <op> by scalar. */
if (VECTOR_INTEGER_TYPE_P (TREE_TYPE (rhs2)))
{
tree first;
- if ((first = ssa_uniform_vector_p (rhs2)) != NULL_TREE)
+ op = optab_for_tree_code (code, type, optab_scalar);
+ if ((first = ssa_uniform_vector_p (rhs2)) != NULL_TREE
+ && (get_compute_type (code, opv, type) != type
+ || get_compute_type (code, op, type) == type))
{
gimple_assign_set_rhs2 (stmt, first);
update_stmt (stmt);
@@ -2164,7 +2169,6 @@ expand_vector_operations_1 (gimple_stmt_
}
}
- opv = optab_for_tree_code (code, type, optab_vector);
if (VECTOR_INTEGER_TYPE_P (TREE_TYPE (rhs2)))
op = opv;
else
but that doesn't really help, because while veclower21 doesn't undo what the
vectorizer carefully did, match.pd during fre5 breaks it again:
/* Prefer vector1 << scalar to vector1 << vector2
if vector2 is uniform. */
(for vec (VECTOR_CST CONSTRUCTOR)
(simplify
(shiftrotate @0 vec@1)
(with { tree tem = uniform_vector_p (@1); }
(if (tem)
(shiftrotate @0 { tem; }))))))
So, does ARM really only have vector shifts and not scalar?
Though, PowerPC seems to have that too, I'll check out what it does on these
testcases.
