--- a/gcc/ipa-pure-const.c	Fri Feb 12 23:41:23 2010 +0900
+++ b/gcc/ipa-pure-const.c	Mon May 24 12:47:05 2010 +0900
@@ -1,5 +1,6 @@
 /* Callgraph based analysis of static variables.
-   Copyright (C) 2004, 2005, 2007, 2008, 2009 Free Software Foundation, Inc.
+   Copyright (C) 2004, 2005, 2007, 2008, 2009, 2010
+   Free Software Foundation, Inc.
    Contributed by Kenneth Zadeck <zadeck@naturalbridge.com>
 
 This file is part of GCC.
@@ -48,12 +49,16 @@
 #include "output.h"
 #include "flags.h"
 #include "timevar.h"
+#include "toplev.h"
 #include "diagnostic.h"
+#include "gimple-pretty-print.h"
 #include "langhooks.h"
 #include "target.h"
 #include "lto-streamer.h"
 #include "cfgloop.h"
 #include "tree-scalar-evolution.h"
+#include "intl.h"
+#include "opts.h"
 
 static struct pointer_set_t *visited_nodes;
 
@@ -105,6 +110,71 @@
 static struct cgraph_2node_hook_list *node_duplication_hook_holder;
 static struct cgraph_node_hook_list *node_removal_hook_holder;
 
+/* Try to guess if function body will always be visible to compiler
+   when compiling the call and whether compiler will be able
+   to propagate the information by itself.  */
+
+static bool
+function_always_visible_to_compiler_p (tree decl)
+{
+  return (!TREE_PUBLIC (decl) || DECL_DECLARED_INLINE_P (decl));
+}
+
+/* Emit suggestion about attribute ATTRIB_NAME for DECL.  KNOWN_FINITE
+   is true if the function is known to be finite.  The diagnostic is
+   controlled by OPTION.  WARNED_ABOUT is a pointer_set unique for
+   OPTION, this function may initialize it and it is always returned
+   by the function.  */
+
+static struct pointer_set_t *
+suggest_attribute (int option, tree decl, bool known_finite,
+		   struct pointer_set_t *warned_about,
+		   const char * attrib_name)
+{
+  if (!option_enabled (option))
+    return warned_about;
+  if (TREE_THIS_VOLATILE (decl)
+      || (known_finite && function_always_visible_to_compiler_p (decl)))
+    return warned_about;
+
+  if (!warned_about)
+    warned_about = pointer_set_create (); 
+  if (pointer_set_contains (warned_about, decl))
+    return warned_about;
+  pointer_set_insert (warned_about, decl);
+  warning_at (DECL_SOURCE_LOCATION (decl),
+	      option,
+	      known_finite
+	      ? _("function might be candidate for attribute %<%s%>")
+	      : _("function might be candidate for attribute %<%s%>"
+		  " if it is known to return normally"), attrib_name);
+  return warned_about;
+}
+
+/* Emit suggestion about __attribute_((pure)) for DECL.  KNOWN_FINITE
+   is true if the function is known to be finite.  */
+
+static void
+warn_function_pure (tree decl, bool known_finite)
+{
+  static struct pointer_set_t *warned_about;
+
+  warned_about 
+    = suggest_attribute (OPT_Wsuggest_attribute_pure, decl,
+			 known_finite, warned_about, "pure");
+}
+
+/* Emit suggestion about __attribute_((const)) for DECL.  KNOWN_FINITE
+   is true if the function is known to be finite.  */
+
+static void
+warn_function_const (tree decl, bool known_finite)
+{
+  static struct pointer_set_t *warned_about;
+  warned_about 
+    = suggest_attribute (OPT_Wsuggest_attribute_const, decl,
+			 known_finite, warned_about, "const");
+}
 /* Init the function state.  */
 
 static void
@@ -159,7 +229,7 @@
 
   /* If the variable has the "used" attribute, treat it as if it had a
      been touched by the devil.  */
-  if (lookup_attribute ("used", DECL_ATTRIBUTES (t)))
+  if (DECL_PRESERVE_P (t))
     {
       local->pure_const_state = IPA_NEITHER;
       if (dump_file)
@@ -324,7 +394,11 @@
 
   /* When not in IPA mode, we can still handle self recursion.  */
   if (!ipa && callee_t == current_function_decl)
-    local->looping = true;
+    {
+      if (dump_file)
+        fprintf (dump_file, "    Recursive call can loop.\n");
+      local->looping = true;
+    }
   /* Either calle is unknown or we are doing local analysis.
      Look to see if there are any bits available for the callee (such as by
      declaration or because it is builtin) and process solely on the basis of
@@ -352,12 +426,20 @@
       if (flags & ECF_CONST)
 	{
           if (callee_t && DECL_LOOPING_CONST_OR_PURE_P (callee_t))
-            local->looping = true;
+	    {
+	      if (dump_file)
+		fprintf (dump_file, "    calls looping pure.\n");
+              local->looping = true;
+	    }
 	 }
       else if (flags & ECF_PURE)
 	{
           if (callee_t && DECL_LOOPING_CONST_OR_PURE_P (callee_t))
-            local->looping = true;
+	    {
+	      if (dump_file)
+		fprintf (dump_file, "    calls looping const.\n");
+              local->looping = true;
+	    }
 	  if (dump_file)
 	    fprintf (dump_file, "    pure function call in not const\n");
 	  if (local->pure_const_state == IPA_CONST)
@@ -452,7 +534,7 @@
       for (i = 0; i < gimple_asm_nclobbers (stmt); i++)
 	{
 	  tree op = gimple_asm_clobber_op (stmt, i);
-	  if (simple_cst_equal(TREE_VALUE (op), memory_identifier_string) == 1)
+	  if (strcmp (TREE_STRING_POINTER (TREE_VALUE (op)), "memory") == 0)
 	    {
               if (dump_file)
                 fprintf (dump_file, "    memory asm clobber is not const/pure");
@@ -603,7 +685,8 @@
      since all we would be interested in are the addressof
      operations.  */
   visited_nodes = pointer_set_create ();
-  set_function_state (node, analyze_function (node, true));
+  if (cgraph_function_body_availability (node) > AVAIL_OVERWRITABLE)
+    set_function_state (node, analyze_function (node, true));
   pointer_set_destroy (visited_nodes);
   visited_nodes = NULL;
 }
@@ -689,7 +772,8 @@
 /* Serialize the ipa info for lto.  */
 
 static void
-pure_const_write_summary (cgraph_node_set set)
+pure_const_write_summary (cgraph_node_set set,
+			  varpool_node_set vset ATTRIBUTE_UNUSED)
 {
   struct cgraph_node *node;
   struct lto_simple_output_block *ob
@@ -937,19 +1021,27 @@
 	  switch (this_state)
 	    {
 	    case IPA_CONST:
-	      if (!TREE_READONLY (w->decl) && dump_file)
-		fprintf (dump_file, "Function found to be %sconst: %s\n",
-			 this_looping ? "looping " : "",
-			 cgraph_node_name (w));
+	      if (!TREE_READONLY (w->decl))
+		{
+		  warn_function_const (w->decl, !this_looping);
+		  if (dump_file)
+		    fprintf (dump_file, "Function found to be %sconst: %s\n",
+			     this_looping ? "looping " : "",
+			     cgraph_node_name (w));
+		}
 	      cgraph_set_readonly_flag (w, true);
 	      cgraph_set_looping_const_or_pure_flag (w, this_looping);
 	      break;
 
 	    case IPA_PURE:
-	      if (!DECL_PURE_P (w->decl) && dump_file)
-		fprintf (dump_file, "Function found to be %spure: %s\n",
-			 this_looping ? "looping " : "",
-			 cgraph_node_name (w));
+	      if (!DECL_PURE_P (w->decl))
+		{
+		  warn_function_pure (w->decl, !this_looping);
+		  if (dump_file)
+		    fprintf (dump_file, "Function found to be %spure: %s\n",
+			     this_looping ? "looping " : "",
+			     cgraph_node_name (w));
+		}
 	      cgraph_set_pure_flag (w, true);
 	      cgraph_set_looping_const_or_pure_flag (w, this_looping);
 	      break;
@@ -1094,13 +1186,37 @@
  generate_summary,		        /* generate_summary */
  pure_const_write_summary,		/* write_summary */
  pure_const_read_summary,		/* read_summary */
- NULL,					/* function_read_summary */
+ NULL,					/* write_optimization_summary */
+ NULL,					/* read_optimization_summary */
  NULL,					/* stmt_fixup */
  0,					/* TODOs */
  NULL,			                /* function_transform */
  NULL					/* variable_transform */
 };
 
+/* Return true if function should be skipped for local pure const analysis.  */
+
+static bool
+skip_function_for_local_pure_const (struct cgraph_node *node)
+{
+  /* Because we do not schedule pass_fixup_cfg over whole program after early optimizations
+     we must not promote functions that are called by already processed functions.  */
+
+  if (function_called_by_processed_nodes_p ())
+    {
+      if (dump_file)
+        fprintf (dump_file, "Function called in recursive cycle; ignoring\n");
+      return true;
+    }
+  if (cgraph_function_body_availability (node) <= AVAIL_OVERWRITABLE)
+    {
+      if (dump_file)
+        fprintf (dump_file, "Function is not available or overwrittable; not analyzing.\n");
+      return true;
+    }
+  return false;
+}
+
 /* Simple local pass for pure const discovery reusing the analysis from
    ipa_pure_const.   This pass is effective when executed together with
    other optimization passes in early optimization pass queue.  */
@@ -1110,25 +1226,15 @@
 {
   bool changed = false;
   funct_state l;
+  bool skip;
   struct cgraph_node *node;
 
-  /* Because we do not schedule pass_fixup_cfg over whole program after early optimizations
-     we must not promote functions that are called by already processed functions.  */
-
-  if (function_called_by_processed_nodes_p ())
-    {
-      if (dump_file)
-        fprintf (dump_file, "Function called in recursive cycle; ignoring\n");
-      return 0;
-    }
   node = cgraph_node (current_function_decl);
-  if (cgraph_function_body_availability (node) <= AVAIL_OVERWRITABLE)
-    {
-      if (dump_file)
-        fprintf (dump_file, "Function has wrong visibility; ignoring\n");
-      return 0;
-    }
-
+  skip = skip_function_for_local_pure_const (node);
+  if (!warn_suggest_attribute_const
+      && !warn_suggest_attribute_pure
+      && skip)
+    return 0;
   l = analyze_function (node, false);
 
   switch (l->pure_const_state)
@@ -1136,9 +1242,13 @@
     case IPA_CONST:
       if (!TREE_READONLY (current_function_decl))
 	{
-	  cgraph_set_readonly_flag (node, true);
-	  cgraph_set_looping_const_or_pure_flag (node, l->looping);
-	  changed = true;
+	  warn_function_const (current_function_decl, !l->looping);
+	  if (!skip)
+	    {
+	      cgraph_set_readonly_flag (node, true);
+	      cgraph_set_looping_const_or_pure_flag (node, l->looping);
+	      changed = true;
+	    }
 	  if (dump_file)
 	    fprintf (dump_file, "Function found to be %sconst: %s\n",
 		     l->looping ? "looping " : "",
@@ -1148,8 +1258,11 @@
       else if (DECL_LOOPING_CONST_OR_PURE_P (current_function_decl)
 	       && !l->looping)
 	{
-	  cgraph_set_looping_const_or_pure_flag (node, false);
-	  changed = true;
+	  if (!skip)
+	    {
+	      cgraph_set_looping_const_or_pure_flag (node, false);
+	      changed = true;
+	    }
 	  if (dump_file)
 	    fprintf (dump_file, "Function found to be non-looping: %s\n",
 		     lang_hooks.decl_printable_name (current_function_decl,
@@ -1158,11 +1271,15 @@
       break;
 
     case IPA_PURE:
-      if (!TREE_READONLY (current_function_decl))
+      if (!DECL_PURE_P (current_function_decl))
 	{
-	  cgraph_set_pure_flag (node, true);
-	  cgraph_set_looping_const_or_pure_flag (node, l->looping);
-	  changed = true;
+	  if (!skip)
+	    {
+	      cgraph_set_pure_flag (node, true);
+	      cgraph_set_looping_const_or_pure_flag (node, l->looping);
+	      changed = true;
+	    }
+	  warn_function_pure (current_function_decl, !l->looping);
 	  if (dump_file)
 	    fprintf (dump_file, "Function found to be %spure: %s\n",
 		     l->looping ? "looping " : "",
@@ -1172,8 +1289,11 @@
       else if (DECL_LOOPING_CONST_OR_PURE_P (current_function_decl)
 	       && !l->looping)
 	{
-	  cgraph_set_looping_const_or_pure_flag (node, false);
-	  changed = true;
+	  if (!skip)
+	    {
+	      cgraph_set_looping_const_or_pure_flag (node, false);
+	      changed = true;
+	    }
 	  if (dump_file)
 	    fprintf (dump_file, "Function found to be non-looping: %s\n",
 		     lang_hooks.decl_printable_name (current_function_decl,