ipa: Better way of applying both IPA-CP and IPA-SRA (PR 103227)

ipa: Better way of applying both IPA-CP and IPA-SRA (PR 103227)

This is basically a better fix for PR 103227.  The one currently in
use, rushed in late at stage3, which means that IPA-CP transformation
simply does a replacement of default-definition of IPA-SRA-created
scalar parameters with a constant, meant that IPA-SRA actually often
led to creation of a bunch of unused parameters, which was rather
ironic and sub-optimal.

This patch rips that old way out and makes sure the clash is resolved
at clone-materialization time.  What happens is that:

1) IPA-SRA IPA analysis (decision) stage recognizes the clash and does
   not create a param adjustment entry for such a scalar component.

2) Clone materialization code checks the IPA-CP transformation
   summary and when it realizes that it is removing a parameter that
   is a base for a discovered IPA-CP aggregate constant, and:

   a) the value is passed by reference, it internally records that any
      load of the value is replaced directly with the known constant
      value.  IPA-SRA will not attempt to split values passed by
      reference when there is a write to it so we know such a load
      won't be on a a LHS.

   b) the value is passed by value, there can be stores to the
      corresponding bit of the aggregate and so all accesses are
      replaced with a new decl and an assignment of the constant to
      this decl is generated at the beginning of the function.

The new testcase contains an xfail as the patch does not fix PR 107640
but it is one that ICEs when one is not careful about remapping
indices of parameters, so I'd like to have it in testsuite/gcc.gd/ipa/
even now.

I don't think that PR 107640 should be attempted through
ipa-param-manipulation replacements because the information is not
really there any more and we'd either need to do the replacements
earlier or dig deep into the clone parent info.  Instead, we should
record somewhere that at the beginning of the function the bits of the
global decl have known values and use that in the value numbering.
That way we could one day encode also known constants in globals that
do not come through parameters.

gcc/ChangeLog:

2022-11-11  Martin Jambor  <mjambor@suse.cz>

	PR ipa/103227
	* ipa-param-manipulation.h (class ipa_param_adjustments): Removed
	member function get_updated_index_or_split.
	(class ipa_param_body_adjustments): New overload of
	register_replacement, new member function append_init_stmts, new
	member m_split_agg_csts_inits.
	* ipa-param-manipulation.cc: Include ipa-prop.h.
	(ipa_param_adjustments::get_updated_index_or_split): Removed.
	(ipa_param_body_adjustments::register_replacement): New overload, use
	it from the older one.
	(ipa_param_body_adjustments::common_initialization): Added the
	capability to create replacements for conflicting IPA-CP discovered
	constants.
	(ipa_param_body_adjustments::ipa_param_body_adjustments): Construct
	the new member.
	(ipa_param_body_adjustments::append_init_stmts): New function.
	* ipa-sra.cc: Include ipa-prop.h.
	(push_param_adjustments_for_index): Require IPA-CP transformation
	summary as a parameter, do not create replacements which are known to
	have constant values.
	(process_isra_node_results): Find and pass to the above function the
	IPA-CP transformation summary.
	* ipa-prop.cc (adjust_agg_replacement_values): Remove the
	functionality replacing IPA-SRA created scalar parameters with
	constants.  Simplify, do not require parameter descriptors, do not
	return anything.
	(ipcp_transform_function): Simplify now that
	adjust_agg_replacement_values does not change cfg.  Move definition
	and initialization of descriptors lower.
	* tree-inline.cc (tree_function_versioning): Call append_init_stmts of
	param_body_adjs, if there are any.

gcc/testsuite/ChangeLog:

2022-11-11  Martin Jambor  <mjambor@suse.cz>

	PR ipa/103227
	PR ipa/107640
	* gcc.dg/ipa/pr107640-2.c: New test.