Group tree-vrp.c by functionality.

Group tree-vrp.c by functionality.

Earlier in this cycle there was some work by Giuliano Belinassi and
myself to refactor tree-vrp.c.  A lot of functions and globals were
moved into independent classes, but the haphazard layout remained.
Assertion methods were indispersed with the propagation code, and with
the jump threading code, etc etc.

This series of patches moves things around so that common
functionality is geographically close.  There is no change in
behavior.

I know this is all slated to go in the next release, but finding
things in the current code base, even if just to compare with the
ranger, is difficult.

Since I keep getting bit by aarch64 regressions, I've tested the whole
set of patches on aarch64, as well as individually on x86-64 Linux.

gcc/ChangeLog:

	* tree-vrp.c (struct assert_locus): Move.
	(class vrp_insert): Rename to vrp_asserts.
	(vrp_insert::build_assert_expr_for): Move to vrp_asserts.
	(fp_predicate): Same.
	(vrp_insert::dump): Same.
	(vrp_insert::register_new_assert_for): Same.
	(extract_code_and_val_from_cond_with_ops): Move.
	(vrp_insert::finish_register_edge_assert_for): Move to vrp_asserts.
	(maybe_set_nonzero_bits): Move.
	(vrp_insert::find_conditional_asserts): Move to vrp_asserts.
	(stmt_interesting_for_vrp): Move.
	(struct case_info): Move.
	(compare_case_labels): Move.
	(lhs_of_dominating_assert): Move.
	(find_case_label_index): Move.
	(find_case_label_range): Move.
	(class vrp_asserts): New.
	(vrp_asserts::build_assert_expr_for): Rename from vrp_insert.
	(vrp_asserts::dump): Same.
	(vrp_asserts::register_new_assert_for): Same.
	(vrp_asserts::finish_register_edge_assert_for): Same.
	(vrp_asserts::find_conditional_asserts): Same.
	(vrp_asserts::compare_case_labels): Same.
	(vrp_asserts::find_switch_asserts): Same.
	(vrp_asserts::find_assert_locations_in_bb): Same.
	(vrp_asserts::find_assert_locations): Same.
	(vrp_asserts::process_assert_insertions_for): Same.
	(vrp_asserts::compare_assert_loc): Same.
	(vrp_asserts::process_assert_insertions): Same.
	(vrp_asserts::insert_range_assertions): Same.
	(vrp_asserts::all_imm_uses_in_stmt_or_feed_cond): Same.
	(vrp_asserts::remove_range_assertions): Same.
	(class vrp_prop): Move.
	(all_imm_uses_in_stmt_or_feed_cond): Move.
	(vrp_prop::vrp_initialize): Move.
	(class vrp_folder): Move.
	(vrp_folder::fold_predicate_in): Move.
	(vrp_folder::fold_stmt): Move.
	(vrp_prop::initialize): Move.
	(vrp_prop::visit_stmt): Move.
	(enum ssa_prop_result): Move.
	(vrp_prop::visit_phi): Move.
	(vrp_prop::finalize): Move.
	(class vrp_dom_walker): Rename to...
	(class vrp_jump_threader): ...this.
	(vrp_jump_threader::before_dom_children): Rename from
	vrp_dom_walker.
	(simplify_stmt_for_jump_threading): Rename to...
	(vrp_jump_threader::simplify_stmt): ...here.
	(vrp_jump_threader::after_dom_children): Same.
	(identify_jump_threads): Move.
	(vrp_prop::vrp_finalize): Move array bounds setup code to...
	(execute_vrp): ...here.