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.

6 files changed, 109 insertions, 8 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
diff --git a/gcc/gimple.h b/gcc/gimple.h
index 23a124e..3cde3cd 100644
--- a/gcc/gimple.h
+++ b/gcc/gimple.h
@@ -1590,6 +1590,7 @@ bool gimple_call_same_target_p (const gimple *, const gimple *);
 int gimple_call_flags (const gimple *);
 int gimple_call_arg_flags (const gcall *, unsigned);
 int gimple_call_retslot_flags (const gcall *);
+int gimple_call_static_chain_flags (const gcall *);
 int gimple_call_return_flags (const gcall *);
 bool gimple_call_nonnull_result_p (gcall *);
 tree gimple_call_nonnull_arg (gcall *);
diff --git a/gcc/ipa-modref.c b/gcc/ipa-modref.c
index c0aae08..bb51312 100644
--- a/gcc/ipa-modref.c
+++ b/gcc/ipa-modref.c
@@ -272,7 +272,8 @@ static GTY(()) fast_function_summary <modref_summary_lto *, va_gc>
 /* Summary for a single function which this pass produces.  */
 
 modref_summary::modref_summary ()
-  : loads (NULL), stores (NULL), retslot_flags (0), writes_errno (false)
+  : loads (NULL), stores (NULL), retslot_flags (0), static_chain_flags (0),
+    writes_errno (false)
 {
 }
 
@@ -327,6 +328,9 @@ modref_summary::useful_p (int ecf_flags, bool check_flags)
   arg_flags.release ();
   if (check_flags && remove_useless_eaf_flags (retslot_flags, ecf_flags, false))
     return true;
+  if (check_flags
+      && remove_useless_eaf_flags (static_chain_flags, ecf_flags, false))
+    return true;
   if (ecf_flags & ECF_CONST)
     return false;
   if (loads && !loads->every_base)
@@ -369,6 +373,7 @@ struct GTY(()) modref_summary_lto
   modref_records_lto *stores;
   auto_vec<eaf_flags_t> GTY((skip)) arg_flags;
   eaf_flags_t retslot_flags;
+  eaf_flags_t static_chain_flags;
   bool writes_errno;
 
   modref_summary_lto ();
@@ -380,7 +385,8 @@ struct GTY(()) modref_summary_lto
 /* Summary for a single function which this pass produces.  */
 
 modref_summary_lto::modref_summary_lto ()
-  : loads (NULL), stores (NULL), retslot_flags (0), writes_errno (false)
+  : loads (NULL), stores (NULL), retslot_flags (0), static_chain_flags (0),
+    writes_errno (false)
 {
 }
 
@@ -408,6 +414,9 @@ modref_summary_lto::useful_p (int ecf_flags, bool check_flags)
   arg_flags.release ();
   if (check_flags && remove_useless_eaf_flags (retslot_flags, ecf_flags, false))
     return true;
+  if (check_flags
+      && remove_useless_eaf_flags (static_chain_flags, ecf_flags, false))
+    return true;
   if (ecf_flags & ECF_CONST)
     return false;
   if (loads && !loads->every_base)
@@ -621,6 +630,11 @@ modref_summary::dump (FILE *out)
       fprintf (out, "  Retslot flags:");
       dump_eaf_flags (out, retslot_flags);
     }
+  if (static_chain_flags)
+    {
+      fprintf (out, "  Static chain flags:");
+      dump_eaf_flags (out, static_chain_flags);
+    }
 }
 
 /* Dump summary.  */
@@ -648,6 +662,11 @@ modref_summary_lto::dump (FILE *out)
       fprintf (out, "  Retslot flags:");
       dump_eaf_flags (out, retslot_flags);
     }
+  if (static_chain_flags)
+    {
+      fprintf (out, "  Static chain flags:");
+      dump_eaf_flags (out, static_chain_flags);
+    }
 }
 
 /* Get function summary for FUNC if it exists, return NULL otherwise.  */
@@ -1417,7 +1436,8 @@ struct escape_point
   /* Extra hidden args we keep track of.  */
   enum hidden_args
   {
-    retslot_arg = -1
+    retslot_arg = -1,
+    static_chain_arg = -2
   };
   /* Value escapes to this call.  */
   gcall *call;
@@ -1787,11 +1807,9 @@ analyze_ssa_name_flags (tree name, vec<modref_lattice> &lattice, int depth,
 		    lattice[index].merge (gimple_call_retslot_flags (call));
 		}
 
-	      /* We do not track accesses to the static chain (we could)
-		 so give up.  */
 	      if (gimple_call_chain (call)
 		  && (gimple_call_chain (call) == name))
-		lattice[index].merge (0);
+		lattice[index].merge (gimple_call_static_chain_flags (call));
 
 	      /* Process internal functions and right away.  */
 	      bool record_ipa = ipa && !gimple_call_internal_p (call);
@@ -1983,6 +2001,7 @@ analyze_parms (modref_summary *summary, modref_summary_lto *summary_lto,
   unsigned int count = 0;
   int ecf_flags = flags_from_decl_or_type (current_function_decl);
   tree retslot = NULL;
+  tree static_chain = NULL;
 
   /* For novops functions we have nothing to gain by EAF flags.  */
   if (ecf_flags & ECF_NOVOPS)
@@ -1992,12 +2011,14 @@ analyze_parms (modref_summary *summary, modref_summary_lto *summary_lto,
   if (DECL_RESULT (current_function_decl)
       && DECL_BY_REFERENCE (DECL_RESULT (current_function_decl)))
     retslot = ssa_default_def (cfun, DECL_RESULT (current_function_decl));
+  if (cfun->static_chain_decl)
+    static_chain = ssa_default_def (cfun, cfun->static_chain_decl);
 
   for (tree parm = DECL_ARGUMENTS (current_function_decl); parm;
        parm = TREE_CHAIN (parm))
     count++;
 
-  if (!count && !retslot)
+  if (!count && !retslot && !static_chain)
     return;
 
   auto_vec<modref_lattice> lattice;
@@ -2071,6 +2092,22 @@ analyze_parms (modref_summary *summary, modref_summary_lto *summary_lto,
 				escape_point::retslot_arg, flags);
 	}
     }
+  if (static_chain)
+    {
+      analyze_ssa_name_flags (static_chain, lattice, 0, ipa);
+      int flags = lattice[SSA_NAME_VERSION (static_chain)].flags;
+
+      flags = remove_useless_eaf_flags (flags, ecf_flags, false);
+      if (flags)
+	{
+	  if (summary)
+	    summary->static_chain_flags = flags;
+	  if (summary_lto)
+	    summary_lto->static_chain_flags = flags;
+	  record_escape_points (lattice[SSA_NAME_VERSION (static_chain)],
+				escape_point::static_chain_arg, flags);
+	}
+    }
   if (ipa)
     for (unsigned int i = 0; i < num_ssa_names; i++)
       lattice[i].release ();
@@ -2355,6 +2392,7 @@ modref_summaries::duplicate (cgraph_node *, cgraph_node *dst,
   if (src_data->arg_flags.length ())
     dst_data->arg_flags = src_data->arg_flags.copy ();
   dst_data->retslot_flags = src_data->retslot_flags;
+  dst_data->static_chain_flags = src_data->static_chain_flags;
 }
 
 /* Called when new clone is inserted to callgraph late.  */
@@ -2381,6 +2419,7 @@ modref_summaries_lto::duplicate (cgraph_node *, cgraph_node *,
   if (src_data->arg_flags.length ())
     dst_data->arg_flags = src_data->arg_flags.copy ();
   dst_data->retslot_flags = src_data->retslot_flags;
+  dst_data->static_chain_flags = src_data->static_chain_flags;
 }
 
 namespace
@@ -2698,6 +2737,7 @@ modref_write ()
 	  for (unsigned int i = 0; i < r->arg_flags.length (); i++)
 	    streamer_write_uhwi (ob, r->arg_flags[i]);
 	  streamer_write_uhwi (ob, r->retslot_flags);
+	  streamer_write_uhwi (ob, r->static_chain_flags);
 
 	  write_modref_records (r->loads, ob);
 	  write_modref_records (r->stores, ob);
@@ -2799,6 +2839,13 @@ read_section (struct lto_file_decl_data *file_data, const char *data,
 	modref_sum->retslot_flags = flags;
       if (modref_sum_lto)
 	modref_sum_lto->retslot_flags = flags;
+
+      flags = streamer_read_uhwi (&ib);
+      if (modref_sum)
+	modref_sum->static_chain_flags = flags;
+      if (modref_sum_lto)
+	modref_sum_lto->static_chain_flags = flags;
+
       read_modref_records (&ib, data_in,
 			   modref_sum ? &modref_sum->loads : NULL,
 			   modref_sum_lto ? &modref_sum_lto->loads : NULL);
@@ -3888,6 +3935,8 @@ modref_merge_call_site_flags (escape_summary *sum,
 	{
 	  eaf_flags_t &f = ee->parm_index == escape_point::retslot_arg
 			   ? cur_summary->retslot_flags
+			   : ee->parm_index == escape_point::static_chain_arg
+			   ? cur_summary->static_chain_flags
 			   : cur_summary->arg_flags[ee->parm_index];
 	  if ((f & flags) != f)
 	    {
@@ -3903,6 +3952,8 @@ modref_merge_call_site_flags (escape_summary *sum,
 	{
 	  eaf_flags_t &f = ee->parm_index == escape_point::retslot_arg
 			   ? cur_summary_lto->retslot_flags
+			   : ee->parm_index == escape_point::static_chain_arg
+			   ? cur_summary_lto->static_chain_flags
 			   : cur_summary_lto->arg_flags[ee->parm_index];
 	  if ((f & flags_lto) != f)
 	    {
diff --git a/gcc/ipa-modref.h b/gcc/ipa-modref.h
index a4db274..ddc8686 100644
--- a/gcc/ipa-modref.h
+++ b/gcc/ipa-modref.h
@@ -32,6 +32,7 @@ struct GTY(()) modref_summary
   modref_records *stores;
   auto_vec<eaf_flags_t> GTY((skip)) arg_flags;
   eaf_flags_t retslot_flags;
+  eaf_flags_t static_chain_flags;
   bool writes_errno;
 
   modref_summary ();
diff --git a/gcc/testsuite/gcc.dg/ipa/modref-3.c b/gcc/testsuite/gcc.dg/ipa/modref-3.c
new file mode 100644
index 0000000..8401354
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ipa/modref-3.c
@@ -0,0 +1,20 @@
+/* { dg-options "-O2 -fdump-ipa-modref"  } */
+/* { dg-do link } */
+int *ptr;
+void linker_error ();
+int
+main ()
+{
+  int a;
+  __attribute__((noinline)) int test2 ()
+  {
+    ptr = 0;
+    return a;
+  }
+  a = 1;
+  test2 ();
+  if (a != 1)
+    linker_error ();
+  return 0;
+}
+/* { dg-final { scan-ipa-dump "Static chain flags: noclobber noescape nodirectescape" "modref" } } */
diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c
index 5f24c01..c70f5af 100644
--- a/gcc/tree-ssa-structalias.c
+++ b/gcc/tree-ssa-structalias.c
@@ -4254,7 +4254,8 @@ handle_rhs_call (gcall *stmt, vec<ce_s> *results,
   /* The static chain escapes as well.  */
   if (gimple_call_chain (stmt))
     handle_call_arg (stmt, gimple_call_chain (stmt), results,
-		     implicit_eaf_flags,
+		     implicit_eaf_flags
+		     | gimple_call_static_chain_flags (stmt),
 		     callescape->id, writes_global_memory);
 
   /* And if we applied NRV the address of the return slot escapes as well.  */