Merge IPA and late local modref flags

[Jan Hubicka]

Hi,
since at the time we compute local solution during late modref the
summaries from IPA are readily available (and I added logic to compare
them), it is easy to intersect both solutions to get around cases
where late optimization obstructate code enough so flags are no longer
analyzed correctly.  This improves PTA disabiguation rage by about 0.5%

Bootstrapped/regtested x86_64-linux, comitted.
gcc/ChangeLog:

	* ipa-modref.c (analyze_parms): Add past_flags, past_retslot_flags
	and past_static_chain; merge past summary with current one.
	(analyze_function): Update.

diff --git a/gcc/ipa-modref.c b/gcc/ipa-modref.c
index 4429bcea803..2f91b563745 100644
--- a/gcc/ipa-modref.c
+++ b/gcc/ipa-modref.c
@@ -2318,11 +2318,18 @@ modref_eaf_analysis::record_escape_points (tree name, int parm_index, int flags)
     }
 }
 
-/* Determine EAF flags for function parameters.  */
+/* Determine EAF flags for function parameters
+   and fill in SUMMARY/SUMMARY_LTO.  If IPA is true work in IPA mode
+   where we also collect scape points.
+   PAST_FLAGS, PAST_RETSLOT_FLAGS, PAST_STATIC_CHAIN_FLAGS can be
+   used to preserve flags from prevoius (IPA) run for cases where
+   late optimizations changed code in a way we can no longer analyze
+   it easily.  */
 
 static void
 analyze_parms (modref_summary *summary, modref_summary_lto *summary_lto,
-	       bool ipa)
+	       bool ipa, vec<eaf_flags_t> &past_flags,
+	       int past_retslot_flags, int past_static_chain_flags)
 {
   unsigned int parm_index = 0;
   unsigned int count = 0;
@@ -2395,6 +2402,25 @@ analyze_parms (modref_summary *summary, modref_summary_lto *summary_lto,
       flags = remove_useless_eaf_flags
 		 (flags, ecf_flags,
 		  VOID_TYPE_P (TREE_TYPE (TREE_TYPE (current_function_decl))));
+      if (past_flags.length () > parm_index)
+	{
+	  int past = past_flags[parm_index];
+	  past = remove_useless_eaf_flags
+		     (past, ecf_flags,
+		      VOID_TYPE_P (TREE_TYPE
+			  (TREE_TYPE (current_function_decl))));
+	  if (dump_file && (flags | past) != flags && !(flags & EAF_UNUSED))
+	    {
+	      fprintf (dump_file,
+		       "  Flags for param %i combined with IPA pass:",
+		       (int)parm_index);
+	      dump_eaf_flags (dump_file, past, false);
+	      fprintf (dump_file, " local ");
+	      dump_eaf_flags (dump_file, flags | past, true);
+	    }
+	  if (!(flags & EAF_UNUSED))
+	    flags |= past;
+	}
 
       if (flags)
 	{
@@ -2416,8 +2442,23 @@ analyze_parms (modref_summary *summary, modref_summary_lto *summary_lto,
   if (retslot)
     {
       int flags = eaf_analysis.get_ssa_name_flags (retslot);
+      int past = past_retslot_flags;
 
       flags = remove_useless_eaf_flags (flags, ecf_flags, false);
+      past = remove_useless_eaf_flags
+		 (past, ecf_flags,
+		  VOID_TYPE_P (TREE_TYPE
+		      (TREE_TYPE (current_function_decl))));
+      if (dump_file && (flags | past) != flags && !(flags & EAF_UNUSED))
+	{
+	  fprintf (dump_file,
+		   "  Retslot flags combined with IPA pass:");
+	  dump_eaf_flags (dump_file, past, false);
+	  fprintf (dump_file, " local ");
+	  dump_eaf_flags (dump_file, flags, true);
+	}
+      if (!(flags & EAF_UNUSED))
+	flags |= past;
       if (flags)
 	{
 	  if (summary)
@@ -2431,8 +2472,23 @@ analyze_parms (modref_summary *summary, modref_summary_lto *summary_lto,
   if (static_chain)
     {
       int flags = eaf_analysis.get_ssa_name_flags (static_chain);
+      int past = past_static_chain_flags;
 
       flags = remove_useless_eaf_flags (flags, ecf_flags, false);
+      past = remove_useless_eaf_flags
+		 (past, ecf_flags,
+		  VOID_TYPE_P (TREE_TYPE
+		      (TREE_TYPE (current_function_decl))));
+      if (dump_file && (flags | past) != flags && !(flags & EAF_UNUSED))
+	{
+	  fprintf (dump_file,
+		   "  Static chain flags combined with IPA pass:");
+	  dump_eaf_flags (dump_file, past, false);
+	  fprintf (dump_file, " local ");
+	  dump_eaf_flags (dump_file, flags, true);
+	}
+      if (!(flags & EAF_UNUSED))
+	lags |= past;
       if (flags)
 	{
 	  if (summary)
@@ -2567,7 +2623,8 @@ analyze_function (function *f, bool ipa)
       summary_lto->writes_errno = false;
     }
 
-  analyze_parms (summary, summary_lto, ipa);
+  analyze_parms (summary, summary_lto, ipa,
+		 past_flags, past_retslot_flags, past_static_chain_flags);
 
   int ecf_flags = flags_from_decl_or_type (current_function_decl);
   auto_vec <gimple *, 32> recursive_calls;
@@ -2662,15 +2719,12 @@ analyze_function (function *f, bool ipa)
 		 VOID_TYPE_P (TREE_TYPE (TREE_TYPE (current_function_decl))));
 	      if (old_flags != new_flags)
 		{
-		  if ((old_flags & ~new_flags) == 0)
+		  if ((old_flags & ~new_flags) == 0
+		      || (new_flags & EAF_UNUSED))
 		    fprintf (dump_file, "  Flags for param %i improved:",
 			     (int)i);
-		  else if ((new_flags & ~old_flags) == 0)
-		    fprintf (dump_file, "  Flags for param %i worsened:",
-			     (int)i);
 		  else
-		    fprintf (dump_file, "  Flags for param %i changed:",
-			     (int)i);
+		    gcc_unreachable ();
 		  dump_eaf_flags (dump_file, old_flags, false);
 		  fprintf (dump_file, " -> ");
 		  dump_eaf_flags (dump_file, new_flags, true);
@@ -2682,12 +2736,11 @@ analyze_function (function *f, bool ipa)
 		 VOID_TYPE_P (TREE_TYPE (TREE_TYPE (current_function_decl))));
 	  if (past_retslot_flags != summary->retslot_flags)
 	    {
-	      if ((past_retslot_flags & ~summary->retslot_flags) == 0)
+	      if ((past_retslot_flags & ~summary->retslot_flags) == 0
+		  || (summary->retslot_flags & EAF_UNUSED))
 		fprintf (dump_file, "  Flags for retslot improved:");
-	      else if ((summary->retslot_flags & ~past_retslot_flags) == 0)
-		fprintf (dump_file, "  Flags for retslot worsened:");
 	      else
-		fprintf (dump_file, "  Flags for retslot changed:");
+		gcc_unreachable ();
 	      dump_eaf_flags (dump_file, past_retslot_flags, false);
 	      fprintf (dump_file, " -> ");
 	      dump_eaf_flags (dump_file, summary->retslot_flags, true);
@@ -2698,13 +2751,11 @@ analyze_function (function *f, bool ipa)
 		 VOID_TYPE_P (TREE_TYPE (TREE_TYPE (current_function_decl))));
 	  if (past_static_chain_flags != summary->static_chain_flags)
 	    {
-	      if ((past_static_chain_flags & ~summary->static_chain_flags) == 0)
+	      if ((past_static_chain_flags & ~summary->static_chain_flags) == 0
+		  || (summary->static_chain_flags & EAF_UNUSED))
 		fprintf (dump_file, "  Flags for static chain improved:");
-	      else if ((summary->static_chain_flags
-			& ~past_static_chain_flags) == 0)
-		fprintf (dump_file, "  Flags for static chain worsened:");
 	      else
-		fprintf (dump_file, "  Flags for static chain changed:");
+		gcc_unreachable ();
 	      dump_eaf_flags (dump_file, past_static_chain_flags, false);
 	      fprintf (dump_file, " -> ");
 	      dump_eaf_flags (dump_file, summary->static_chain_flags, true);