7ac7e2868d
This patch splits can_vec_perm_p into two functions: can_vec_perm_var_p
for testing permute operations with variable selection vectors, and
can_vec_perm_const_p for testing permute operations with specific
constant selection vectors. This means that we can pass the constant
selection vector by reference.
Constant permutes can still use a variable permute as a fallback.
A later patch adds a check to makre sure that we don't truncate the
vector indices when doing this.
However, have_whole_vector_shift checked:
if (direct_optab_handler (vec_perm_const_optab, mode) == CODE_FOR_nothing)
return false;
which had the effect of disallowing the fallback to variable permutes.
I'm not sure whether that was the intention or whether it was just
supposed to short-cut the loop on targets that don't support permutes.
(But then why bother? The first check in the loop would fail and
we'd bail out straightaway.)
The patch adds a parameter for disallowing the fallback. I think it
makes sense to do this for the following code in the VEC_PERM_EXPR
folder:
/* Some targets are deficient and fail to expand a single
argument permutation while still allowing an equivalent
2-argument version. */
if (need_mask_canon && arg2 == op2
&& !can_vec_perm_p (TYPE_MODE (type), false, &sel)
&& can_vec_perm_p (TYPE_MODE (type), false, &sel2))
since it's really testing whether the expand_vec_perm_const code expects
a particular form.
2018-01-02 Richard Sandiford <richard.sandiford@linaro.org>
gcc/
* optabs-query.h (can_vec_perm_p): Delete.
(can_vec_perm_var_p, can_vec_perm_const_p): Declare.
* optabs-query.c (can_vec_perm_p): Split into...
(can_vec_perm_var_p, can_vec_perm_const_p): ...these two functions.
(can_mult_highpart_p): Use can_vec_perm_const_p to test whether a
particular selector is valid.
* tree-ssa-forwprop.c (simplify_vector_constructor): Likewise.
* tree-vect-data-refs.c (vect_grouped_store_supported): Likewise.
(vect_grouped_load_supported): Likewise.
(vect_shift_permute_load_chain): Likewise.
* tree-vect-slp.c (vect_build_slp_tree_1): Likewise.
(vect_transform_slp_perm_load): Likewise.
* tree-vect-stmts.c (perm_mask_for_reverse): Likewise.
(vectorizable_bswap): Likewise.
(vect_gen_perm_mask_checked): Likewise.
* fold-const.c (fold_ternary_loc): Likewise. Don't take
implementations of variable permutation vectors into account
when deciding which selector to use.
* tree-vect-loop.c (have_whole_vector_shift): Don't check whether
vec_perm_const_optab is supported; instead use can_vec_perm_const_p
with a false third argument.
* tree-vect-generic.c (lower_vec_perm): Use can_vec_perm_const_p
to test whether the constant selector is valid and can_vec_perm_var_p
to test whether a variable selector is valid.
From-SVN: r256091
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