ipa-sra: Restructure how cloning and call redirection communicate (PR 93385)

I was asked by Richi to split my fix for PR 93385 for easier review
into IPA-SRA materialization refactoring and the actual DCE addition.
Fortunately it was mostly natural except for a temporary weird
condition in ipa_param_body_adjustments::modify_call_stmt.
Additionally.  In addition to the patch I posted previously, this one
also deallocated the newly added summary in toplev::finalize and fixes
a mistakenly uninitialized field.

This is the first part which basically replaces performed_splits in
clone_info and the code which generates it, keeps it up-to-date and
consumes it with new edge summaries which are much nicer.  It simply
contains 1) a mapping from the original argument indices to the actual
indices in the call statement as it is now, 2) information needed to
identify arguments representing pass-through IPA-SRA splits with which
have been added to the call arguments in place of an original
argument/reference and 3) a delta to the index where va_args may start
- so basically directly all the information that the consumer of
performed_splits had to compute and we also do not need the weird
dummy declarations.

The main disadvantage is that the information has to be created (and
kept up-to-date) for all call graph edges associated with the given
statement from all clones (including inline clones) of the clone where
splitting or removal happened first.  But all of this happens during
clone materialization so the only effect on WPA memory consumption is
the removal of a pointer from clone_info.

The statement modification code also has to know the statement from
the original function in order to be able to locate the edge summaries
which at this point are still keyed to these.  However, the code is
already quite heavily dependant on how things are structured in
tree-inline.c and in order to fix bugs like these it probably has to
be.

The subsequent patch needs this new information to be able to remove
arguments from calls during materialization and communicate this
information to the call redirection.

gcc/ChangeLog:

2021-05-17  Martin Jambor  <mjambor@suse.cz>

	PR ipa/93385
	* symtab-clones.h (clone_info): Removed member param_adjustments.
	* ipa-param-manipulation.h: Adjust initial comment to reflect how we
	deal with pass-through splits now.
	(ipa_param_performed_split): Removed.
	(ipa_param_adjustments::modify_call): Adjusted parameters.
	(class ipa_param_body_adjustments): Adjusted parameters of
	register_replacement, modify_gimple_stmt and modify_call_stmt.
	(ipa_verify_edge_has_no_modifications): Declare.
	(ipa_edge_modifications_finalize): Declare.
	* cgraph.c (cgraph_edge::redirect_call_stmt_to_callee): Remove
	performed_splits processing, pas only edge to padjs->modify_call,
	check that call arguments were not modified if they should not have
	been.
	* cgraphclones.c (cgraph_node::create_clone): Do not copy performed
	splits.
	* ipa-param-manipulation.c (struct pass_through_split_map): New type.
	(ipa_edge_modification_info): Likewise.
	(ipa_edge_modification_sum): Likewise.
	(ipa_edge_modifications): New edge summary.
	(ipa_verify_edge_has_no_modifications): New function.
	(transitive_split_p): Removed.
	(transitive_split_map): Likewise.
	(init_transitive_splits): Likewise.
	(ipa_param_adjustments::modify_call): Adjusted to use the new edge
	summary instead of performed_splits.
	(ipa_param_body_adjustments::register_replacement): Drop dummy
	parameter, set base_index of the created ipa_param_body_replacement.
	(phi_arg_will_live_p): New function.
	(ipa_param_body_adjustments::common_initialization): Do not create
	IPA_SRA dummy decls.
	(simple_tree_swap_info): Removed.
	(remap_split_decl_to_dummy): Likewise.
	(record_argument_state_1): New function.
	(record_argument_state): Likewise.
	(ipa_param_body_adjustments::modify_call_stmt): New parameter
	orig_stmt.  Do not work with dummy decls, save necessary info about
	changes to ipa_edge_modifications.
	(ipa_param_body_adjustments::modify_gimple_stmt): New parameter
	orig_stmt, pass it to modify_call_stmt.
	(ipa_param_body_adjustments::modify_cfun_body): Adjust call to
	modify_gimple_stmt.
	(ipa_edge_modifications_finalize): New function.
	* tree-inline.c (remap_gimple_stmt): Pass original statement to
	modify_gimple_stmt.
	(copy_phis_for_bb): Do not copy dead PHI nodes.
	(expand_call_inline): Do not remap performed_splits.
	(update_clone_info): Likewise.
	* toplev.c: Include ipa-param-manipulation.h.
	(toplev::finalize): Call ipa_edge_modifications_finalize.