Improve base tracking in ipa-modref

on exchange2 benchamrk we miss some useful propagation because modref gives
up very early on analyzing accesses through pointers.  For example in
int test (int *a)
{
  int i;
  for (i=0; a[i];i++);
  return i+a[i];
}

We are not able to determine that a[i] accesses are relative to a.
This is because get_access requires the SSA name that is in MEM_REF to be
PARM_DECL while on other places we use ipa-prop helper to work out the proper
base pointers.

This patch commonizes the code in get_access and parm_map_for_arg so both
use the check properly and extends it to also figure out that newly allocated
memory is not a side effect to caller.

gcc/ChangeLog:

2021-11-21  Jan Hubicka  <hubicka@ucw.cz>

	PR ipa/103227
	* ipa-modref.c (parm_map_for_arg): Rename to ...
	(parm_map_for_ptr): .. this one; handle static chain and calls to
	malloc functions.
	(modref_access_analysis::get_access): Use parm_map_for_ptr.
	(modref_access_analysis::process_fnspec): Update.
	(modref_access_analysis::analyze_load): Update.
	(modref_access_analysis::analyze_store): Update.

gcc/testsuite/ChangeLog:

2021-11-21  Jan Hubicka  <hubicka@ucw.cz>

	PR ipa/103227
	* gcc.dg/tree-ssa/modref-15.c: New test.

0 files changed, 0 insertions, 0 deletions