refactor SLP constant insertion and provde entry insert helper

This provides helpers to insert stmts on region entry abstracted
from loop/basic-block split out from vec_init_vector and used
from the SLP constant code generation path.  The SLP constant
code generation path is also changed to avoid needless SSA
copying since we can store VECTOR_CSTs directly in the vectorized
defs array, improving the IL from the vectorizer.

2020-07-03  Richard Biener  <rguenther@suse.de>

	* tree-vectorizer.h (vec_info::insert_on_entry): New.
	(vec_info::insert_seq_on_entry): Likewise.
	* tree-vectorizer.c (vec_info::insert_on_entry): Implement.
	(vec_info::insert_seq_on_entry): Likewise.
	* tree-vect-stmts.c (vect_init_vector_1): Use
	vec_info::insert_on_entry.
	(vect_finish_stmt_generation): Set modified bit after
	adjusting VUSE.
	* tree-vect-slp.c (vect_create_constant_vectors): Simplify
	by using vec_info::insert_seq_on_entry and bypassing
	vec_init_vector.
	(vect_schedule_slp_instance): Deal with all-constant
	children later.

1 files changed, 40 insertions, 0 deletions

diff --git a/gcc/tree-vectorizer.c b/gcc/tree-vectorizer.c
index 78d9da6..26a1846 100644
--- a/gcc/tree-vectorizer.c
+++ b/gcc/tree-vectorizer.c
@@ -625,6 +625,46 @@ vec_info::replace_stmt (gimple_stmt_iterator *gsi, stmt_vec_info stmt_info,
   gsi_replace (gsi, new_stmt, true);
 }
 
+/* Insert stmts in SEQ on the VEC_INFO region entry.  If CONTEXT is
+   not NULL it specifies whether to use the sub-region entry
+   determined by it, currently used for loop vectorization to insert
+   on the inner loop entry vs. the outer loop entry.  */
+
+void
+vec_info::insert_seq_on_entry (stmt_vec_info context, gimple_seq seq)
+{
+  if (loop_vec_info loop_vinfo = dyn_cast <loop_vec_info> (this))
+    {
+      class loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
+      basic_block new_bb;
+      edge pe;
+
+      if (context && nested_in_vect_loop_p (loop, context))
+	loop = loop->inner;
+
+      pe = loop_preheader_edge (loop);
+      new_bb = gsi_insert_seq_on_edge_immediate (pe, seq);
+      gcc_assert (!new_bb);
+    }
+  else
+    {
+      bb_vec_info bb_vinfo = as_a <bb_vec_info> (this);
+      gimple_stmt_iterator gsi_region_begin = bb_vinfo->region_begin;
+      gsi_insert_seq_before (&gsi_region_begin, seq, GSI_SAME_STMT);
+    }
+}
+
+/* Like insert_seq_on_entry but just inserts the single stmt NEW_STMT.  */
+
+void
+vec_info::insert_on_entry (stmt_vec_info context, gimple *new_stmt)
+{
+  gimple_seq seq = NULL;
+  gimple_stmt_iterator gsi = gsi_start (seq);
+  gsi_insert_before_without_update (&gsi, new_stmt, GSI_SAME_STMT);
+  insert_seq_on_entry (context, seq);
+}
+
 /* Create and initialize a new stmt_vec_info struct for STMT.  */
 
 stmt_vec_info