middle-end/38474 - fix alias walk budget accounting in IPA analysis

middle-end/38474 - fix alias walk budget accounting in IPA analysis

The walk_aliased_vdef calls do not update the walking budget until
it is hit by a single call (and then in one case it resumes with
no limit at all).  The following rectifies this in multiple places.
It also makes the updates more consistend and fixes
determine_known_aggregate_parts to account its own alias queries.

2021-02-12  Richard Biener  <rguenther@suse.de>

	PR middle-end/38474
	* ipa-fnsummary.c (unmodified_parm_1): Only walk when
	fbi->aa_walk_budget is bigger than zero.  Update
	fbi->aa_walk_budget.
	(param_change_prob): Likewise.
	* ipa-prop.c (detect_type_change_from_memory_writes):
	Properly account walk_aliased_vdefs.
	(parm_preserved_before_stmt_p): Canonicalize updates.
	(parm_ref_data_preserved_p): Likewise.
	(parm_ref_data_pass_through_p): Likewise.
	(determine_known_aggregate_parts): Account own alias queries.