ipa/104303 - miscompilation of gnatmake

ipa/104303 - miscompilation of gnatmake

Modref attempts to track memory accesses relative to the base pointers
which are parameters of functions.
If it fails, it still makes difference between unknown memory access and
global memory access.  The second makes it possible to disambiguate with
memory that is not accessible from outside world (i.e. everything that does
not escape from the caller function).  This is useful so we do not punt
when unknown function is called.

The added ref_may_access_global_memory_p ends up using
ptr_deref_may_alias_global_p which does not consider escaped automatic
variables as global.  For modref those are still global since they
can be accessed from functions called.

The following adds a flag to the *_global_p APIs indicating whether
escaped local memory should be considered as global or not and
removes ref_may_access_global_memory_p in favor of using
ref_may_alias_global_p with the flag set to true.

2022-04-07  Richard Biener  <rguenther@suse.de>
	    Jan Hubicka  <hubicka@ucw.cz>

	PR ipa/104303
	* tree-ssa-alias.h (ptr_deref_may_alias_global_p,
	ref_may_alias_global_p, ref_may_alias_global_p,
	stmt_may_clobber_global_p, pt_solution_includes_global): Add
	bool parameters indicating whether escaped locals should be
	considered global.
	* tree-ssa-structalias.cc (pt_solution_includes_global):
	When the new escaped_nonlocal_p flag is true also consider
	pt->vars_contains_escaped.
	* tree-ssa-alias.cc (ptr_deref_may_alias_global_p):
	Pass down new escaped_nonlocal_p flag.
	(ref_may_alias_global_p): Likewise.
	(stmt_may_clobber_global_p): Likewise.
	(ref_may_alias_global_p_1): Likewise.  For decls also
	query the escaped solution if true.
	(ref_may_access_global_memory_p): Remove.
	(modref_may_conflict): Use ref_may_alias_global_p with
	escaped locals considered global.
	(ref_maybe_used_by_stmt_p): Adjust.
	* ipa-fnsummary.cc (points_to_local_or_readonly_memory_p):
	Likewise.
	* tree-ssa-dse.cc (dse_classify_store): Likewise.
	* trans-mem.cc (thread_private_new_memory): Likewise, but
	consider escaped locals global.
	* tree-ssa-dce.cc (mark_stmt_if_obviously_necessary): Likewise.

	* gnat.dg/concat5.adb: New.
	* gnat.dg/concat5_pkg1.adb: Likewise.
	* gnat.dg/concat5_pkg1.ads: Likewise.
	* gnat.dg/concat5_pkg2.adb: Likewise.
	* gnat.dg/concat5_pkg2.ads: Likewise.