[PATCH v2 06/13] vect: Make vect_maybe_permute_loop_masks optional and retargetable

Change vect_maybe_permute_loop_masks so that it can check if the
permutation is possible without code generation.

Additionally, allow overriding of what controls to use for source and
target.

gcc/ChangeLog:

	* tree-vect-loop-manip.cc (vect_maybe_permute_loop_masks):
	Make the function optional and retargetable.
---
 gcc/tree-vect-loop-manip.cc | 32 ++++++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
index cee3779e37f..10fc0353078 100644
--- a/gcc/tree-vect-loop-manip.cc
+++ b/gcc/tree-vect-loop-manip.cc
@@ -324,18 +324,30 @@ interleave_supported_p (vec_perm_indices *indices, tree vectype,
 			       *indices);
 }
 
-/* Try to use permutes to define the masks in DEST_RGM using the masks
-   in SRC_RGM, given that the former has twice as many masks as the
-   latter.  Return true on success, adding any new statements to SEQ.  */
+/* Check if its possible to use permutes to define the masks in DEST_RGM using
+   the masks in SRC_RGM, given that the former has twice as many masks as the
+   latter.  Return true on success.
+
+   Optionally, if SEQ is non-null add new statements for the permutation to SEQ.
+   Additionally, if SRC_MASKS and DST_MASKS are defined, use these instead
+   of the masks from SRC_RGM and DST_RGM.  */
 
 static bool
 vect_maybe_permute_loop_masks (gimple_seq *seq, rgroup_controls *dest_rgm,
-			       rgroup_controls *src_rgm)
+			       rgroup_controls *src_rgm,
+			       vec<tree> *dst_masks = NULL,
+			       vec<tree> *src_masks = NULL)
 {
   tree src_masktype = src_rgm->type;
   tree dest_masktype = dest_rgm->type;
+  if (!src_masktype && !seq)
+    return true;
   machine_mode src_mode = TYPE_MODE (src_masktype);
   insn_code icode1, icode2;
+
+  vec<tree> src_controls = src_masks ? *src_masks : src_rgm->controls;
+  vec<tree> dst_controls = dst_masks ? *dst_masks : dest_rgm->controls;
+
   if (dest_rgm->max_nscalars_per_iter <= src_rgm->max_nscalars_per_iter
       && (icode1 = optab_handler (vec_unpacku_hi_optab,
 				  src_mode)) != CODE_FOR_nothing
@@ -347,10 +359,12 @@ vect_maybe_permute_loop_masks (gimple_seq *seq, rgroup_controls *dest_rgm,
       machine_mode dest_mode = insn_data[icode1].operand[0].mode;
       gcc_assert (dest_mode == insn_data[icode2].operand[0].mode);
       tree unpack_masktype = vect_halve_mask_nunits (src_masktype, dest_mode);
+      if (!seq)
+	return true;
       for (unsigned int i = 0; i < dest_rgm->controls.length (); ++i)
 	{
-	  tree src = src_rgm->controls[i / 2];
-	  tree dest = dest_rgm->controls[i];
+	  tree src = src_controls[i / 2];
+	  tree dest = dst_controls[i];
 	  tree_code code = ((i & 1) == (BYTES_BIG_ENDIAN ? 0 : 1)
 			    ? VEC_UNPACK_HI_EXPR
 			    : VEC_UNPACK_LO_EXPR);
@@ -375,6 +389,8 @@ vect_maybe_permute_loop_masks (gimple_seq *seq, rgroup_controls *dest_rgm,
       && interleave_supported_p (&indices[0], src_masktype, 0)
       && interleave_supported_p (&indices[1], src_masktype, 1))
     {
+      if (!seq)
+	return true;
       /* The destination requires twice as many mask bits as the source, so
 	 we can use interleaving permutes to double up the number of bits.  */
       tree masks[2];
@@ -382,8 +398,8 @@ vect_maybe_permute_loop_masks (gimple_seq *seq, rgroup_controls *dest_rgm,
 	masks[i] = vect_gen_perm_mask_checked (src_masktype, indices[i]);
       for (unsigned int i = 0; i < dest_rgm->controls.length (); ++i)
 	{
-	  tree src = src_rgm->controls[i / 2];
-	  tree dest = dest_rgm->controls[i];
+	  tree src = src_controls[i / 2];
+	  tree dest = dst_controls[i];
 	  gimple *stmt = gimple_build_assign (dest, VEC_PERM_EXPR,
 					      src, src, masks[i & 1]);
 	  gimple_seq_add_stmt (seq, stmt);
-- 
2.43.0