Determine global memory accesses in ipa-modref

Determine global memory accesses in ipa-modref

As discussed in PR103585, fatigue2 is now only benchmark from my usual testing
set (SPEC2k6, SPEC2k17, CPP benchmarks, polyhedron, Firefox, clang) which sees
important regression when inlining functions called once is limited.  This
prevents us from solving runtime issues in roms benchmarks and elsewhere.

The problem is that there is perdida function that takes many arguments and
some of them are array descriptors.  We constant propagate most of their fields
but still keep their initialization. Because perdida is quite fast, the call
overhead dominates, since we need over 100 memory stores consuing about 35%
of the overall benchmark runtime.

The memory stores would be eliminated if perdida did not call fortran I/O which
makes modref to thin that the array descriptors could be accessed. We are
quite close discovering that they can't becuase they are non-escaping from
function.  This patch makes modref to distingush between global memory access
(only things that escapes) and unkonwn accesss (that may access also
nonescaping things reaching the function).  This makes disambiguation for
functions containing error handling better.

Unfortunately the patch hits two semi-latent issues in Fortran frontned.
First is wrong code in gfortran.dg/unlimited_polymorphic_3.f03. This can be
turned into wrong code testcase on both mainline and gcc11 if the runtime
call is removed, so I filled PR 103662 for it. There is TBAA mismatch for
structure produced in FE.

Second is issue with GOMP where Fortran marks certain parameters as non-escaping
and then makes them escape via GOMP_parallel.  For this I disabled the use of
escape info in verify_arg which also disables the useful transform on perdida
but still does useful work for e.g. GCC error handling.  I will work on this
incrementally.

Bootstrapped/regtested x86_64-linux, lto-bootstrapped and also tested with
clang build.  I plan to commit this tomorrow if there are no complains
(the patch is not completely short but conceptualy simple and handles a lot
of common cases).

gcc/ChangeLog:

2021-12-12  Jan Hubicka  <hubicka@ucw.cz>

	PR ipa/103585
	* ipa-modref-tree.c (modref_access_node::range_info_useful_p): Handle
	MODREF_GLOBAL_MEMORY_PARM.
	(modref_access_node::dump): Likewise.
	(modref_access_node::get_call_arg): Likewise.
	* ipa-modref-tree.h (enum modref_special_parms): Add
	MODREF_GLOBAL_MEMORY_PARM.
	(modref_access_node::useful_for_kill): Handle
	MODREF_GLOBAL_MEMORY_PARM.
	(modref:tree::merge): Add promote_unknown_to_global.
	* ipa-modref.c (verify_arg):New function.
	(may_access_nonescaping_parm_p): New function.
	(modref_access_analysis::record_global_memory_load): New member
	function.
	(modref_access_analysis::record_global_memory_store): Likewise.
	(modref_access_analysis::process_fnspec): Distingush global and local
	memory.
	(modref_access_analysis::analyze_call): Likewise.
	* tree-ssa-alias.c (ref_may_access_global_memory_p): New function.
	(modref_may_conflict): Use it.

gcc/testsuite/ChangeLog:

2021-12-12  Jan Hubicka  <hubicka@ucw.cz>

	* gcc.dg/analyzer/data-model-1.c: Disable ipa-modref.
	* gcc.dg/uninit-38.c: Likewise.
	* gcc.dg/uninit-pr98578.c: Liewise.