Move gimplify_buildN API local to only remaining user

This moves the legacy gimplify_buildN API to tree-vect-generic.c,
its only user and elides the gimplification step, making it a wrapper
around gimple_build, adjusting tree_vec_extract for this.

I've noticed that vector CTOR expansion doesn't deal with unfolded
{} and thus this makes it more resilent.  I've also adjusted the
match.pd vector CTOR extraction code to make sure it doesn't
produce a CTOR when folding would make it a vector constant.

2021-04-15  Richard Biener  <rguenther@suse.de>

	* tree-cfg.h (gimplify_build1): Remove.
	(gimplify_build2): Likewise.
	(gimplify_build3): Likewise.
	* tree-cfg.c (gimplify_build1): Move to tree-vect-generic.c.
	(gimplify_build2): Likewise.
	(gimplify_build3): Likewise.
	* tree-vect-generic.c (gimplify_build1): Move from tree-cfg.c.
	Modernize.
	(gimplify_build2): Likewise.
	(gimplify_build3): Likewise.
	(tree_vec_extract): Use resimplify with following SSA edges.
	(expand_vector_parallel): Avoid passing NULL size/bitpos
	to tree_vec_extract.
	* expr.c (store_constructor): Deal with zero-element CTORs.
	* match.pd (bit_field_ref <vector CTOR>): Make sure to
	produce vector constants when possible.

1 files changed, 3 insertions, 1 deletions

diff --git a/gcc/expr.c b/gcc/expr.c
index a0e1946..5ed716c 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -7019,7 +7019,9 @@ store_constructor (tree exp, rtx target, int cleared, poly_int64 size,
 	/* Compute the size of the elements in the CTOR.  It differs
 	   from the size of the vector type elements only when the
 	   CTOR elements are vectors themselves.  */
-	tree val_type = TREE_TYPE (CONSTRUCTOR_ELT (exp, 0)->value);
+	tree val_type = (CONSTRUCTOR_NELTS (exp) != 0
+			 ? TREE_TYPE (CONSTRUCTOR_ELT (exp, 0)->value)
+			 : elttype);
 	if (VECTOR_TYPE_P (val_type))
 	  bitsize = tree_to_uhwi (TYPE_SIZE (val_type));
 	else