re PR tree-optimization/54713 (error: non-trivial conversion at assignment in gcc.c-torture/compile/pr53410-2.c)

	PR tree-optimization/54713
	* expr.c (categorize_ctor_elements_1): Don't assume purpose is
	non-NULL.
	* tree-cfg.c (verify_gimple_assign_single): Add verification of
	vector CONSTRUCTORs.
	* tree-ssa-sccvn.c (vn_reference_lookup_3): For VECTOR_TYPE
	CONSTRUCTORs, don't do anything if element type is VECTOR_TYPE,
	and don't check index.
	* tree-vect-slp.c (vect_get_constant_vectors): VIEW_CONVERT_EXPR
	ctor elements first if their type isn't compatible with vector
	element type.

From-SVN: r191983