tree-vect-stmts.c (vectorizable_store): Perform vector extracts via vectors if supported...

2017-08-02  Richard Biener  <rguenther@suse.de>

	* tree-vect-stmts.c (vectorizable_store): Perform vector extracts
	via vectors if supported, integer extracts via punning if supported
	or otherwise vector extracts.

From-SVN: r250813

gcc/ChangeLog

 2017-08-02  Richard Biener  <rguenther@suse.de>
 
+	* tree-vect-stmts.c (vectorizable_store): Perform vector extracts
+	via vectors if supported, integer extracts via punning if supported
+	or otherwise vector extracts.
+
+2017-08-02  Richard Biener  <rguenther@suse.de>
+
 	* tree-ssa-pre.c (bitmap_insert_into_set_1): Remove and inline
 	into ...
 	(bitmap_insert_into_set): ... this.

gcc/tree-vect-stmts.c

@@ -6002,6 +6002,7 @@ vectorizable_store (gimple *stmt, gimple_stmt_iterator *gsi, gimple **vec_stmt,
       unsigned nstores = nunits;
       unsigned lnel = 1;
       tree ltype = elem_type;
+      tree lvectype = vectype;
       if (slp)
 	{
 	  if (group_size < nunits
@@ -6010,6 +6011,45 @@ vectorizable_store (gimple *stmt, gimple_stmt_iterator *gsi, gimple **vec_stmt,
 	      nstores = nunits / group_size;
 	      lnel = group_size;
 	      ltype = build_vector_type (elem_type, group_size);
+	      lvectype = vectype;
+
+	      /* First check if vec_extract optab doesn't support extraction
+		 of vector elts directly.  */
+	      machine_mode elmode = TYPE_MODE (elem_type);
+	      machine_mode vmode = mode_for_vector (elmode, group_size);
+	      if (! VECTOR_MODE_P (vmode)
+		  || (convert_optab_handler (vec_extract_optab,
+					     TYPE_MODE (vectype), vmode)
+		      == CODE_FOR_nothing))
+		{
+		  /* Try to avoid emitting an extract of vector elements
+		     by performing the extracts using an integer type of the
+		     same size, extracting from a vector of those and then
+		     re-interpreting it as the original vector type if
+		     supported.  */
+		  unsigned lsize
+		    = group_size * GET_MODE_BITSIZE (elmode);
+		  elmode = mode_for_size (lsize, MODE_INT, 0);
+		  vmode = mode_for_vector (elmode, nunits / group_size);
+		  /* If we can't construct such a vector fall back to
+		     element extracts from the original vector type and
+		     element size stores.  */
+		  if (VECTOR_MODE_P (vmode)
+		      && (convert_optab_handler (vec_extract_optab,
+						 vmode, elmode)
+			  != CODE_FOR_nothing))
+		    {
+		      nstores = nunits / group_size;
+		      lnel = group_size;
+		      ltype = build_nonstandard_integer_type (lsize, 1);
+		      lvectype = build_vector_type (ltype, nstores);
+		    }
+		  /* Else fall back to vector extraction anyway.
+		     Fewer stores are more important than avoiding spilling
+		     of the vector we extract from.  Compared to the
+		     construction case in vectorizable_load no store-forwarding
+		     issue exists here for reasonable archs.  */
+		}
 	    }
 	  else if (group_size >= nunits
 		   && group_size % nunits == 0)
@@ -6017,6 +6057,7 @@ vectorizable_store (gimple *stmt, gimple_stmt_iterator *gsi, gimple **vec_stmt,
 	      nstores = 1;
 	      lnel = nunits;
 	      ltype = vectype;
+	      lvectype = vectype;
 	    }
 	  ltype = build_aligned_type (ltype, TYPE_ALIGN (elem_type));
 	  ncopies = SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node);
@@ -6087,7 +6128,16 @@ vectorizable_store (gimple *stmt, gimple_stmt_iterator *gsi, gimple **vec_stmt,
 		      vec_oprnd = vect_get_vec_def_for_stmt_copy (dt, vec_oprnd);
 		    }
 		}
-
+	      /* Pun the vector to extract from if necessary.  */
+	      if (lvectype != vectype)
+		{
+		  tree tem = make_ssa_name (lvectype);
+		  gimple *pun
+		    = gimple_build_assign (tem, build1 (VIEW_CONVERT_EXPR,
+							lvectype, vec_oprnd));
+		  vect_finish_stmt_generation (stmt, pun, gsi);
+		  vec_oprnd = tem;
+		}
 	      for (i = 0; i < nstores; i++)
 		{
 		  tree newref, newoff;