[PATCH] tree-optimization/101809 - support emulated gather for double[int]

[Richard Biener <rguenther@suse.de>]

This adds emulated gather support for index vectors with more
elements than the data vector.  The internal function gather
vectorization code doesn't currently handle this (but the builtin
decl code does).  This allows vectorization of double data gather
with int indexes on 32bit platforms where there isn't an implicit
widening to 64bit present.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

2021-08-10  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/101809
	* tree-vect-stmts.c (get_load_store_type): Allow emulated
	gathers with offset vector nunits being a constant multiple
	of the data vector nunits.
	(vect_get_gather_scatter_ops): Use the appropriate nunits
	for the offset vector defs.
	(vectorizable_store): Adjust call to
	vect_get_gather_scatter_ops.
	(vectorizable_load): Likewise.  Handle the case of less
	offset vectors than data vectors.
---
 gcc/tree-vect-stmts.c | 47 +++++++++++++++++++++++++++----------------
 1 file changed, 30 insertions(+), 17 deletions(-)

diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
index 5a5a4dab3f2..ab402b57fb4 100644
--- a/gcc/tree-vect-stmts.c
+++ b/gcc/tree-vect-stmts.c
@@ -2377,9 +2377,11 @@ get_load_store_type (vec_info  *vinfo, stmt_vec_info stmt_info,
 	      return false;
 	    }
 	  else if (!TYPE_VECTOR_SUBPARTS (vectype).is_constant ()
-		   || !known_eq (TYPE_VECTOR_SUBPARTS (vectype),
-				 TYPE_VECTOR_SUBPARTS
-				   (gs_info->offset_vectype)))
+		   || !TYPE_VECTOR_SUBPARTS
+			 (gs_info->offset_vectype).is_constant ()
+		   || !constant_multiple_p (TYPE_VECTOR_SUBPARTS
+					      (gs_info->offset_vectype),
+					    TYPE_VECTOR_SUBPARTS (vectype)))
 	    {
 	      if (dump_enabled_p ())
 		dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
@@ -2928,11 +2930,10 @@ vect_build_gather_load_calls (vec_info *vinfo, stmt_vec_info stmt_info,
    containing loop.  */
 
 static void
-vect_get_gather_scatter_ops (vec_info *vinfo,
+vect_get_gather_scatter_ops (loop_vec_info loop_vinfo,
 			     class loop *loop, stmt_vec_info stmt_info,
 			     gather_scatter_info *gs_info,
-			     tree *dataref_ptr, vec<tree> *vec_offset,
-			     unsigned ncopies)
+			     tree *dataref_ptr, vec<tree> *vec_offset)
 {
   gimple_seq stmts = NULL;
   *dataref_ptr = force_gimple_operand (gs_info->base, &stmts, true, NULL_TREE);
@@ -2943,8 +2944,10 @@ vect_get_gather_scatter_ops (vec_info *vinfo,
       new_bb = gsi_insert_seq_on_edge_immediate (pe, stmts);
       gcc_assert (!new_bb);
     }
-  vect_get_vec_defs_for_operand (vinfo, stmt_info, ncopies, gs_info->offset,
-				 vec_offset, gs_info->offset_vectype);
+  unsigned ncopies = vect_get_num_copies (loop_vinfo, gs_info->offset_vectype);
+  vect_get_vec_defs_for_operand (loop_vinfo, stmt_info, ncopies,
+				 gs_info->offset, vec_offset,
+				 gs_info->offset_vectype);
 }
 
 /* Prepare to implement a grouped or strided load or store using
@@ -8072,8 +8075,9 @@ vectorizable_store (vec_info *vinfo,
 	    }
 	  else if (STMT_VINFO_GATHER_SCATTER_P (stmt_info))
 	    {
-	      vect_get_gather_scatter_ops (vinfo, loop, stmt_info, &gs_info,
-					   &dataref_ptr, &vec_offsets, ncopies);
+	      vect_get_gather_scatter_ops (loop_vinfo, loop, stmt_info,
+					   &gs_info, &dataref_ptr,
+					   &vec_offsets);
 	      vec_offset = vec_offsets[0];
 	    }
 	  else
@@ -9376,9 +9380,9 @@ vectorizable_load (vec_info *vinfo,
 	    }
 	  else if (STMT_VINFO_GATHER_SCATTER_P (stmt_info))
 	    {
-	      vect_get_gather_scatter_ops (vinfo, loop, stmt_info, &gs_info,
-					   &dataref_ptr, &vec_offsets, ncopies);
-	      vec_offset = vec_offsets[0];
+	      vect_get_gather_scatter_ops (loop_vinfo, loop, stmt_info,
+					   &gs_info, &dataref_ptr,
+					   &vec_offsets);
 	    }
 	  else
 	    dataref_ptr
@@ -9395,9 +9399,7 @@ vectorizable_load (vec_info *vinfo,
 	  if (dataref_offset)
 	    dataref_offset = int_const_binop (PLUS_EXPR, dataref_offset,
 					      bump);
-	  else if (STMT_VINFO_GATHER_SCATTER_P (stmt_info))
-	    vec_offset = vec_offsets[j];
-	  else
+	  else if (!STMT_VINFO_GATHER_SCATTER_P (stmt_info))
 	    dataref_ptr = bump_vector_ptr (vinfo, dataref_ptr, ptr_incr, gsi,
 					   stmt_info, bump);
 	  if (mask)
@@ -9490,6 +9492,7 @@ vectorizable_load (vec_info *vinfo,
 		    if (memory_access_type == VMAT_GATHER_SCATTER
 			&& gs_info.ifn != IFN_LAST)
 		      {
+			vec_offset = vec_offsets[j];
 			tree zero = build_zero_cst (vectype);
 			tree scale = size_int (gs_info.scale);
 			gcall *call;
@@ -9512,9 +9515,18 @@ vectorizable_load (vec_info *vinfo,
 			gcc_assert (!final_mask);
 			unsigned HOST_WIDE_INT const_nunits
 			  = nunits.to_constant ();
+			unsigned HOST_WIDE_INT const_offset_nunits
+			  = TYPE_VECTOR_SUBPARTS (gs_info.offset_vectype)
+			      .to_constant ();
 			vec<constructor_elt, va_gc> *ctor_elts;
 			vec_alloc (ctor_elts, const_nunits);
 			gimple_seq stmts = NULL;
+			/* We support offset vectors with more elements
+			   than the data vector for now.  */
+			unsigned HOST_WIDE_INT factor
+			  = const_offset_nunits / const_nunits;
+			vec_offset = vec_offsets[j / factor];
+			unsigned elt_offset = (j % factor) * const_nunits;
 			tree idx_type = TREE_TYPE (TREE_TYPE (vec_offset));
 			tree scale = size_int (gs_info.scale);
 			align
@@ -9525,7 +9537,8 @@ vectorizable_load (vec_info *vinfo,
 			  {
 			    tree boff = size_binop (MULT_EXPR,
 						    TYPE_SIZE (idx_type),
-						    bitsize_int (k));
+						    bitsize_int
+						      (k + elt_offset));
 			    tree idx = gimple_build (&stmts, BIT_FIELD_REF,
 						     idx_type, vec_offset,
 						     TYPE_SIZE (idx_type),
-- 
2.31.1