https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94727
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to rsand...@gcc.gnu.org from comment #5)
> Well, this is a bit of mess (surprise). We have a "<" comparison
> between two booleans that are leaves of the SLP tree, so
> vectorizable_comparison falls back on:
>
> /* Invariant comparison. */
> if (!vectype)
> {
> vectype = get_vectype_for_scalar_type (vinfo, TREE_TYPE (rhs1),
> slp_node);
> if (maybe_ne (TYPE_VECTOR_SUBPARTS (vectype), nunits))
> return false;
> }
>
> rhs1 and rhs2 are *unsigned* boolean types, so we get back a vector
> of unsigned integers. All is well, and "<" works as expected without
> the need for:
>
> /* Boolean values may have another representation in vectors
> and therefore we prefer bit operations over comparison for
> them (which also works for scalar masks). We store opcodes
> to use in bitop1 and bitop2. Statement is vectorized as
> BITOP2 (rhs1 BITOP1 rhs2) or
> rhs1 BITOP2 (BITOP1 rhs2)
> depending on bitop1 and bitop2 arity. */
> bool swap_p = false;
> if (VECTOR_BOOLEAN_TYPE_P (vectype))
> {
>
> However, we then defer to vect_get_slp_defs to get the actual operands.
> The expected vector type is not part of this interface.
Ah yeah - sth on my list to fix (not making the type part of that API
but assigning vector types to SLP nodes). I even have partly completed
"hacks" to do that. When we have (and use!) vector types on all SLP
nodes we can also get rid of the mismatch code.
> The request
> goes to vect_get_constant_vectors, which does:
>
> if (VECT_SCALAR_BOOLEAN_TYPE_P (TREE_TYPE (op))
> && vect_mask_constant_operand_p (stmt_vinfo))
> vector_type = truth_type_for (stmt_vectype);
> else
> vector_type = get_vectype_for_scalar_type (vinfo, TREE_TYPE (op),
> op_node);
>
> So the function gives back a vector of mask types, which here are
> vectors of *signed* booleans. This means that "<" gives:
>
> true (-1) < false (0)
>
> and so the boolean fixup above was needed after all.
>
> I'm going to try:
>
> diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
> index 7f3a9fb5fb3..88a1e2c51d2 100644
> --- a/gcc/tree-vect-stmts.c
> +++ b/gcc/tree-vect-stmts.c
> @@ -10566,8 +10566,11 @@ vectorizable_comparison (stmt_vec_info stmt_info,
> gimple_stmt_iterator *gsi,
> /* Invariant comparison. */
> if (!vectype)
> {
> - vectype = get_vectype_for_scalar_type (vinfo, TREE_TYPE (rhs1),
> - slp_node);
> + if (VECT_SCALAR_BOOLEAN_TYPE_P (TREE_TYPE (rhs1)))
> + vectype = mask_type;
> + else
> + vectype = get_vectype_for_scalar_type (vinfo, TREE_TYPE (rhs1),
> + slp_node);
> if (!vectype || maybe_ne (TYPE_VECTOR_SUBPARTS (vectype), nunits))
> return false;
> }
>
> which does at least fix the testcase.
LGTM.
