Static chain support in ipa-modref

Teach ipa-modref about the static chain that is, like
retslot, a hiden argument.  The patch is pretty much symemtric to what
was done for retslot handling and I verified it does the intended job
for Ada LTO bootstrap.

gcc/ChangeLog:

	* gimple.c (gimple_call_static_chain_flags): New function.
	* gimple.h (gimple_call_static_chain_flags): Declare
	* ipa-modref.c (modref_summary::modref_summary): Initialize
	static_chain_flags.
	(modref_summary_lto::modref_summary_lto): Likewise.
	(modref_summary::useful_p): Test static_chain_flags.
	(modref_summary_lto::useful_p): Likewise.
	(struct modref_summary_lto): Add static_chain_flags.
	(modref_summary::dump): Dump static_chain_flags.
	(modref_summary_lto::dump): Likewise.
	(struct escape_point): Add static_cahin_arg.
	(analyze_ssa_name_flags): Use gimple_call_static_chain_flags.
	(analyze_parms): Handle static chains.
	(modref_summaries::duplicate): Duplicate static_chain_flags.
	(modref_summaries_lto::duplicate): Likewise.
	(modref_write): Stream static_chain_flags.
	(read_section): Likewise.
	(modref_merge_call_site_flags): Handle static_chain_flags.
	* ipa-modref.h (struct modref_summary): Add static_chain_flags.
	* tree-ssa-structalias.c (handle_rhs_call): Use
	gimple_static_chain_flags.

gcc/testsuite/ChangeLog:

	* gcc.dg/ipa/modref-3.c: New test.

1 files changed, 27 insertions, 0 deletions

diff --git a/gcc/gimple.c b/gcc/gimple.c
index 22dd641..76768c1 100644
--- a/gcc/gimple.c
+++ b/gcc/gimple.c
@@ -1647,6 +1647,33 @@ gimple_call_retslot_flags (const gcall *stmt)
   return flags;
 }
 
+/* Detects argument flags for static chain on call STMT.  */
+
+int
+gimple_call_static_chain_flags (const gcall *stmt)
+{
+  int flags = 0;
+
+  tree callee = gimple_call_fndecl (stmt);
+  if (callee)
+    {
+      cgraph_node *node = cgraph_node::get (callee);
+      modref_summary *summary = node ? get_modref_function_summary (node)
+				: NULL;
+
+      if (summary)
+	{
+	  int modref_flags = summary->static_chain_flags;
+
+	  /* We have possibly optimized out load.  Be conservative here.  */
+	  gcc_checking_assert (node->binds_to_current_def_p ());
+	  if (dbg_cnt (ipa_mod_ref_pta))
+	    flags |= modref_flags;
+	}
+    }
+  return flags;
+}
+
 /* Detects return flags for the call STMT.  */
 
 int