tree-optimization/102570 - teach VN about internal functions

tree-optimization/102570 - teach VN about internal functions

We're now using internal functions for a lot of stuff but there's
still missing VN support out of laziness.  The following instantiates
support and adds testcases for FRE and PRE (hoisting).

2021-10-04  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/102570
	* tree-ssa-sccvn.h (vn_reference_op_struct): Document
	we are using clique for the internal function code.
	* tree-ssa-sccvn.c (vn_reference_op_eq): Compare the
	internal function code.
	(print_vn_reference_ops): Print the internal function code.
	(vn_reference_op_compute_hash): Hash it.
	(copy_reference_ops_from_call): Record it.
	(visit_stmt): Remove the restriction around internal function
	calls.
	(fully_constant_vn_reference_p): Use fold_const_call and handle
	internal functions.
	(vn_reference_eq): Compare call return types.
	* tree-ssa-pre.c (create_expression_by_pieces): Handle
	generating calls to internal functions.
	(compute_avail): Remove the restriction around internal function
	calls.

	* gcc.dg/tree-ssa/ssa-fre-96.c: New testcase.
	* gcc.dg/tree-ssa/ssa-pre-33.c: Likewise.