Merge evrp uses of substitute_and_fold_engine into the engine itself.

Merge evrp uses of substitute_and_fold_engine into the engine itself.

This patch merges the evrp uses of the substitute and fold engine into
the engine itself, at least the parts that can be re-used by other
engine uses.  It also adds a context parameter to get_value() for
further use.

gcc/
	* gimple-loop-versioning.cc (loop_versioning::name_prop::get_value):
	Add stmt parameter.
	* gimple-ssa-evrp.c (class evrp_folder): New.
	(class evrp_dom_walker): Remove.
	(execute_early_vrp): Use evrp_folder instead of evrp_dom_walker.
	* tree-ssa-ccp.c (ccp_folder::get_value): Add stmt parameter.
	* tree-ssa-copy.c (copy_folder::get_value): Same.
	* tree-ssa-propagate.c (substitute_and_fold_engine::replace_uses_in):
	Pass stmt to get_value.
	(substitute_and_fold_engine::replace_phi_args_in): Same.
	(substitute_and_fold_dom_walker::after_dom_children): Call
	post_fold_bb.
	(substitute_and_fold_dom_walker::foreach_new_stmt_in_bb): New.
	(substitute_and_fold_dom_walker::propagate_into_phi_args): New.
	(substitute_and_fold_dom_walker::before_dom_children): Adjust to
	call virtual functions for folding, pre_folding, and post folding.
	Call get_value with PHI.  Tweak dump.
	* tree-ssa-propagate.h (class substitute_and_fold_engine):
	New argument to get_value.
	New virtual function pre_fold_bb.
	New virtual function post_fold_bb.
	New virtual function pre_fold_stmt.
	New virtual function post_new_stmt.
	New function propagate_into_phi_args.
	* tree-vrp.c (vrp_folder::get_value): Add stmt argument.
	* vr-values.c (vr_values::extract_range_from_stmt): Adjust dump
	output.
	(vr_values::fold_cond): New.
	(vr_values::simplify_cond_using_ranges_1): Call fold_cond.
	* vr-values.h (class vr_values): Add
	simplify_cond_using_ranges_when_edge_is_known.
gcc/testsuite/
	* gcc.dg/tree-ssa/ssa-dse-30.c: Adjust test for folding of
	memmove happening later.