Make vec_perm_indices use new vector encoding

This patch changes vec_perm_indices from a plain vec<> to a class
that stores a canonicalized permutation, using the same encoding
as for VECTOR_CSTs.  This means that vec_perm_indices now carries
information about the number of vectors being permuted (currently
always 1 or 2) and the number of elements in each input vector.

A new vec_perm_builder class is used to actually build up the vector,
like tree_vector_builder does for trees.  vec_perm_indices is the
completed representation, a bit like VECTOR_CST is for trees.

The patch just does a mechanical conversion of the code to
vec_perm_builder: a later patch uses explicit encodings where possible.

The point of all this is that it makes the representation suitable
for variable-length vectors.  It's no longer necessary for the
underlying vec<>s to store every element explicitly.

In int-vector-builder.h, "using the same encoding as tree and rtx constants"
describes the endpoint -- adding the rtx encoding comes later.

2018-01-02  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	* int-vector-builder.h: New file.
	* vec-perm-indices.h: Include int-vector-builder.h.
	(vec_perm_indices): Redefine as an int_vector_builder.
	(auto_vec_perm_indices): Delete.
	(vec_perm_builder): Redefine as a stand-alone class.
	(vec_perm_indices::vec_perm_indices): New function.
	(vec_perm_indices::clamp): Likewise.
	* vec-perm-indices.c: Include fold-const.h and tree-vector-builder.h.
	(vec_perm_indices::new_vector): New function.
	(vec_perm_indices::new_expanded_vector): Update for new
	vec_perm_indices class.
	(vec_perm_indices::rotate_inputs): New function.
	(vec_perm_indices::all_in_range_p): Operate directly on the
	encoded form, without computing elided elements.
	(tree_to_vec_perm_builder): Operate directly on the VECTOR_CST
	encoding.  Update for new vec_perm_indices class.
	* optabs.c (expand_vec_perm_const): Create a vec_perm_indices for
	the given vec_perm_builder.
	(expand_vec_perm_var): Update vec_perm_builder constructor.
	(expand_mult_highpart): Use vec_perm_builder instead of
	auto_vec_perm_indices.
	* optabs-query.c (can_mult_highpart_p): Use vec_perm_builder and
	vec_perm_indices instead of auto_vec_perm_indices.  Use a single
	or double series encoding as appropriate.
	* fold-const.c (fold_ternary_loc): Use vec_perm_builder and
	vec_perm_indices instead of auto_vec_perm_indices.
	* tree-ssa-forwprop.c (simplify_vector_constructor): Likewise.
	* tree-vect-data-refs.c (vect_grouped_store_supported): Likewise.
	(vect_permute_store_chain): Likewise.
	(vect_grouped_load_supported): Likewise.
	(vect_permute_load_chain): Likewise.
	(vect_shift_permute_load_chain): Likewise.
	* tree-vect-slp.c (vect_build_slp_tree_1): Likewise.
	(vect_transform_slp_perm_load): Likewise.
	(vect_schedule_slp_instance): Likewise.
	* tree-vect-stmts.c (perm_mask_for_reverse): Likewise.
	(vectorizable_mask_load_store): Likewise.
	(vectorizable_bswap): Likewise.
	(vectorizable_store): Likewise.
	(vectorizable_load): Likewise.
	* tree-vect-generic.c (lower_vec_perm): Use vec_perm_builder and
	vec_perm_indices instead of auto_vec_perm_indices.  Use
	tree_to_vec_perm_builder to read the vector from a tree.
	* tree-vect-loop.c (calc_vec_perm_mask_for_shift): Take a
	vec_perm_builder instead of a vec_perm_indices.
	(have_whole_vector_shift): Use vec_perm_builder and
	vec_perm_indices instead of auto_vec_perm_indices.  Leave the
	truncation to calc_vec_perm_mask_for_shift.
	(vect_create_epilog_for_reduction): Likewise.
	* config/aarch64/aarch64.c (expand_vec_perm_d::perm): Change
	from auto_vec_perm_indices to vec_perm_indices.
	(aarch64_expand_vec_perm_const_1): Use rotate_inputs on d.perm
	instead of changing individual elements.
	(aarch64_vectorize_vec_perm_const): Use new_vector to install
	the vector in d.perm.
	* config/arm/arm.c (expand_vec_perm_d::perm): Change
	from auto_vec_perm_indices to vec_perm_indices.
	(arm_expand_vec_perm_const_1): Use rotate_inputs on d.perm
	instead of changing individual elements.
	(arm_vectorize_vec_perm_const): Use new_vector to install
	the vector in d.perm.
	* config/powerpcspe/powerpcspe.c (rs6000_expand_extract_even):
	Update vec_perm_builder constructor.
	(rs6000_expand_interleave): Likewise.
	* config/rs6000/rs6000.c (rs6000_expand_extract_even): Likewise.
	(rs6000_expand_interleave): Likewise.

From-SVN: r256095

1 files changed, 10 insertions, 12 deletions

diff --git a/gcc/tree-vect-generic.c b/gcc/tree-vect-generic.c
index 7daf9aebd97..767721cd62c 100644
--- a/gcc/tree-vect-generic.c
+++ b/gcc/tree-vect-generic.c
@@ -1299,15 +1299,13 @@ lower_vec_perm (gimple_stmt_iterator *gsi)
 	mask = gimple_assign_rhs1 (def_stmt);
     }
 
-  if (TREE_CODE (mask) == VECTOR_CST)
-    {
-      auto_vec_perm_indices sel_int (elements);
-
-      for (i = 0; i < elements; ++i)
-	sel_int.quick_push (TREE_INT_CST_LOW (VECTOR_CST_ELT (mask, i))
-			    & (2 * elements - 1));
+  vec_perm_builder sel_int;
 
-      if (can_vec_perm_const_p (TYPE_MODE (vect_type), sel_int))
+  if (TREE_CODE (mask) == VECTOR_CST
+      && tree_to_vec_perm_builder (&sel_int, mask))
+    {
+      vec_perm_indices indices (sel_int, 2, elements);
+      if (can_vec_perm_const_p (TYPE_MODE (vect_type), indices))
 	{
 	  gimple_assign_set_rhs3 (stmt, mask);
 	  update_stmt (stmt);
@@ -1319,14 +1317,14 @@ lower_vec_perm (gimple_stmt_iterator *gsi)
 	  != CODE_FOR_nothing
 	  && TREE_CODE (vec1) == VECTOR_CST
 	  && initializer_zerop (vec1)
-	  && sel_int[0]
-	  && sel_int[0] < elements)
+	  && indices[0]
+	  && indices[0] < elements)
 	{
 	  for (i = 1; i < elements; ++i)
 	    {
-	      unsigned int expected = i + sel_int[0];
+	      unsigned int expected = i + indices[0];
 	      /* Indices into the second vector are all equivalent.  */
-	      if (MIN (elements, (unsigned) sel_int[i])
+	      if (MIN (elements, (unsigned) indices[i])
 		  != MIN (elements, expected))
  		break;
 	    }