* cgraph.c (cgraph_edge_cannot_lead_to_return): Also check

	if caller is noreturn.
	* ipa-reference.c (analyze_function): Use ipa_ref_cannot_lead_to_return
	* ipa-ref.h (ipa_ref_cannot_lead_to_return): New function.
	* ipa-ref.c (ipa_ref_cannot_lead_to_return): New function.
	* ipa-pure-const.c (check_decl): Add IPA parameter.
	(state_from_flags): New function.
	(better_state, worse_state): New functions.
	(check_call): When in IPA mode, do not care about callees.
	(check_load, check_store): Update.
	(check_ipa_load, check_ipa_store): New.
	(check_stmt): When in IPA mode, use IPA checkers.
	(analyze_function): Use state_from_flags.
	(propagate): Check indirect edges and references.


git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@160380 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 224 insertions, 121 deletions

diff --git a/gcc/ipa-pure-const.c b/gcc/ipa-pure-const.c
index 299019a145c..9055a66e94a 100644
--- a/gcc/ipa-pure-const.c
+++ b/gcc/ipa-pure-const.c
@@ -227,7 +227,7 @@ set_function_state (struct cgraph_node *node, funct_state s)
 
 static inline void
 check_decl (funct_state local,
-	    tree t, bool checking_write)
+	    tree t, bool checking_write, bool ipa)
 {
   /* Do not want to do anything with volatile except mark any
      function that uses one to be not const or pure.  */
@@ -253,6 +253,11 @@ check_decl (funct_state local,
       return;
     }
 
+  /* In IPA mode we are not interested in checking actual loads and stores;
+     they will be processed at propagation time using ipa_ref.  */
+  if (ipa)
+    return;
+
   /* Since we have dealt with the locals and params cases above, if we
      are CHECKING_WRITE, this cannot be a pure or constant
      function.  */
@@ -333,6 +338,78 @@ check_op (funct_state local, tree t, bool checking_write)
     }
 }
 
+/* compute state based on ECF FLAGS and store to STATE and LOOPING.  */
+
+static void
+state_from_flags (enum pure_const_state_e *state, bool *looping,
+	          int flags, bool cannot_lead_to_return)
+{
+  *looping = false;
+  if (flags & ECF_LOOPING_CONST_OR_PURE)
+    {
+      *looping = true;
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file, " looping");
+    }
+  if (flags & ECF_CONST)
+    {
+      *state = IPA_CONST;
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file, " const\n");
+    }
+  else if (flags & ECF_PURE)
+    {
+      *state = IPA_PURE;
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file, " pure\n");
+    }
+  else if (cannot_lead_to_return)
+    {
+      *state = IPA_PURE;
+      *looping = true;
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file, " ignoring side effects->pure looping\n");
+    }
+  else
+    {
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file, " neihter\n");
+      *state = IPA_NEITHER;
+      *looping = true;
+    }
+}
+
+/* Merge STATE and STATE2 and LOOPING and LOOPING2 and store
+   into STATE and LOOPING better of the two variants.
+   Be sure to merge looping correctly.  IPA_NEITHER functions
+   have looping 0 even if they don't have to return.  */
+
+static inline void
+better_state (enum pure_const_state_e *state, bool *looping,
+	      enum pure_const_state_e state2, bool looping2)
+{
+  if (state2 < *state)
+    {
+      if (*state == IPA_NEITHER)
+	*looping = looping2;
+      else
+	*looping = MIN (*looping, looping2);
+    }
+  else if (state2 != IPA_NEITHER)
+    *looping = MIN (*looping, looping2);
+}
+
+/* Merge STATE and STATE2 and LOOPING and LOOPING2 and store
+   into STATE and LOOPING worse of the two variants.  */
+
+static inline void
+worse_state (enum pure_const_state_e *state, bool *looping,
+	     enum pure_const_state_e state2, bool looping2)
+{
+  *state = MAX (*state, state2);
+  *looping = MAX (*looping, looping2);
+}
+
 /* Check the parameters of a function call to CALL_EXPR to see if
    there are any references in the parameters that are not allowed for
    pure or const functions.  Also check to see if this is either an
@@ -422,8 +499,10 @@ check_call (funct_state local, gimple call, bool ipa)
      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
      those bits. */
-  else if (!ipa || !callee_t)
+  else if (!ipa)
     {
+      enum pure_const_state_e call_state;
+      bool call_looping;
       if (possibly_throws && cfun->can_throw_non_call_exceptions)
         {
 	  if (dump_file)
@@ -442,68 +521,61 @@ check_call (funct_state local, gimple call, bool ipa)
 	    }
           local->can_throw = true;
 	}
-      if (flags & ECF_CONST)
-	{
-          if (callee_t && DECL_LOOPING_CONST_OR_PURE_P (callee_t))
-	    {
-	      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))
-	    {
-	      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)
-	    local->pure_const_state = IPA_PURE;
-	}
-      else if ((flags & (ECF_NORETURN | ECF_NOTHROW))
-	       == (ECF_NORETURN | ECF_NOTHROW)
-	       || (!flag_exceptions && (flags & ECF_NORETURN)))
-	{
-	  if (dump_file)
-	    fprintf (dump_file, "    noreturn nothrow call is looping pure\n");
-	  if (local->pure_const_state == IPA_CONST)
-	    local->pure_const_state = IPA_PURE;
-          local->looping = true;
-	}
-      else
-	{
-	  if (dump_file)
-	    fprintf (dump_file, "    uknown function call is not const/pure\n");
-	  local->pure_const_state = IPA_NEITHER;
-          local->looping = true;
-	}
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file, "    checking flags for call:");
+      state_from_flags (&call_state, &call_looping, flags,
+			((flags & (ECF_NORETURN | ECF_NOTHROW))
+			 == (ECF_NORETURN | ECF_NOTHROW))
+			|| (!flag_exceptions && (flags & ECF_NORETURN)));
+      worse_state (&local->pure_const_state, &local->looping,
+		   call_state, call_looping);
     }
   /* Direct functions calls are handled by IPA propagation.  */
 }
 
-/* Wrapper around check_decl for loads.  */
+/* Wrapper around check_decl for loads in local more.  */
 
 static bool
 check_load (gimple stmt ATTRIBUTE_UNUSED, tree op, void *data)
 {
   if (DECL_P (op))
-    check_decl ((funct_state)data, op, false);
+    check_decl ((funct_state)data, op, false, false);
   else
     check_op ((funct_state)data, op, false);
   return false;
 }
 
-/* Wrapper around check_decl for stores.  */
+/* Wrapper around check_decl for stores in local more.  */
 
 static bool
 check_store (gimple stmt ATTRIBUTE_UNUSED, tree op, void *data)
 {
   if (DECL_P (op))
-    check_decl ((funct_state)data, op, true);
+    check_decl ((funct_state)data, op, true, false);
+  else
+    check_op ((funct_state)data, op, true);
+  return false;
+}
+
+/* Wrapper around check_decl for loads in ipa mode.  */
+
+static bool
+check_ipa_load (gimple stmt ATTRIBUTE_UNUSED, tree op, void *data)
+{
+  if (DECL_P (op))
+    check_decl ((funct_state)data, op, false, true);
+  else
+    check_op ((funct_state)data, op, false);
+  return false;
+}
+
+/* Wrapper around check_decl for stores in ipa mode.  */
+
+static bool
+check_ipa_store (gimple stmt ATTRIBUTE_UNUSED, tree op, void *data)
+{
+  if (DECL_P (op))
+    check_decl ((funct_state)data, op, true, true);
   else
     check_op ((funct_state)data, op, true);
   return false;
@@ -527,7 +599,9 @@ check_stmt (gimple_stmt_iterator *gsip, funct_state local, bool ipa)
     }
 
   /* Look for loads and stores.  */
-  walk_stmt_load_store_ops (stmt, local, check_load, check_store);
+  walk_stmt_load_store_ops (stmt, local,
+			    ipa ? check_ipa_load : check_load,
+			    ipa ? check_ipa_store :  check_store);
 
   if (gimple_code (stmt) != GIMPLE_CALL
       && stmt_could_throw_p (stmt))
@@ -669,21 +743,15 @@ end:
 	}
     }
 
-  if (TREE_READONLY (decl))
-    {
-      l->pure_const_state = IPA_CONST;
-      l->state_previously_known = IPA_CONST;
-      if (!DECL_LOOPING_CONST_OR_PURE_P (decl))
-        l->looping = false, l->looping_previously_known = false;
-    }
-  if (DECL_PURE_P (decl))
-    {
-      if (l->pure_const_state != IPA_CONST)
-        l->pure_const_state = IPA_PURE;
-      l->state_previously_known = IPA_PURE;
-      if (!DECL_LOOPING_CONST_OR_PURE_P (decl))
-        l->looping = false, l->looping_previously_known = false;
-    }
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    fprintf (dump_file, "    checking previously known:");
+  state_from_flags (&l->state_previously_known, &l->looping_previously_known,
+		    flags_from_decl_or_type (fn->decl),
+		    cgraph_node_cannot_return (fn));
+
+  better_state (&l->pure_const_state, &l->looping,
+		l->state_previously_known,
+		l->looping_previously_known);
   if (TREE_NOTHROW (decl))
     l->can_throw = false;
 
@@ -953,6 +1021,7 @@ self_recursive_p (struct cgraph_node *node)
   return false;
 }
 
+
 /* Produce the global information by preforming a transitive closure
    on the local information that was produced by generate_summary.
    Note that there is no function_transform pass since this only
@@ -995,9 +1064,13 @@ propagate (void)
 
       /* Find the worst state for any node in the cycle.  */
       w = node;
-      while (w)
+      while (w && pure_const_state != IPA_NEITHER)
 	{
 	  struct cgraph_edge *e;
+	  struct cgraph_edge *ie;
+	  int i;
+	  struct ipa_ref *ref;
+
 	  funct_state w_l = get_function_state (w);
 	  if (dump_file && (dump_flags & TDF_DETAILS))
 	    fprintf (dump_file, "  Visiting %s/%i state:%s looping %i\n",
@@ -1005,16 +1078,19 @@ propagate (void)
 		     w->uid,
 		     pure_const_names[w_l->pure_const_state],
 		     w_l->looping);
-	  if (pure_const_state < w_l->pure_const_state)
-	    pure_const_state = w_l->pure_const_state;
 
-	  if (w_l->looping)
-	    looping = true;
+	  /* First merge in function body properties.  */
+	  worse_state (&pure_const_state, &looping,
+		       w_l->pure_const_state, w_l->looping);
+	  if (pure_const_state == IPA_NEITHER)
+	    break;
+
+	  /* For overwritable nodes we can not assume anything.  */
 	  if (cgraph_function_body_availability (w) == AVAIL_OVERWRITABLE)
 	    {
-	      looping |= w_l->looping_previously_known;
-	      if (pure_const_state < w_l->state_previously_known)
-	        pure_const_state = w_l->state_previously_known;
+	      worse_state (&pure_const_state, &looping,
+			   w_l->state_previously_known,
+			   w_l->looping_previously_known);
 	      if (dump_file && (dump_flags & TDF_DETAILS))
 		{
 		  fprintf (dump_file,
@@ -1022,16 +1098,18 @@ propagate (void)
 			   pure_const_names[w_l->state_previously_known],
 			   w_l->looping_previously_known);
 		}
+	      break;
 	    }
 
-	  if (pure_const_state == IPA_NEITHER)
-	    break;
-
 	  count++;
 
+	  /* We consider recursive cycles as possibly infinite.
+	     This might be relaxed since infinite recursion leads to stack
+	     overflow.  */
 	  if (count > 1)
 	    looping = true;
 
+	  /* Now walk the edges and merge in callee properties.  */
 	  for (e = w->callees; e; e = e->next_callee)
 	    {
 	      struct cgraph_node *y = e->callee;
@@ -1059,10 +1137,9 @@ propagate (void)
 		      && cgraph_edge_cannot_lead_to_return (e))
 		    {
 		      if (dump_file && (dump_flags & TDF_DETAILS))
-			{	
-			  fprintf (dump_file,
-				   "        Ignoring side effects -> pure, looping\n");
-			}
+			fprintf (dump_file,
+				 "        Ignoring side effects"
+				 " -> pure, looping\n");
 		      edge_state = IPA_PURE;
 		      edge_looping = true;
 		    }
@@ -1073,55 +1150,78 @@ propagate (void)
 		    }
 		}
 	      else
-	        {
-		  int flags = flags_from_decl_or_type (y->decl);
+		state_from_flags (&edge_state, &edge_looping,
+			          flags_from_decl_or_type (y->decl),
+			          cgraph_edge_cannot_lead_to_return (e));
+
+	      /* Merge the results with what we already know.  */
+	      better_state (&edge_state, &edge_looping,
+			    w_l->state_previously_known,
+			    w_l->looping_previously_known);
+	      worse_state (&pure_const_state, &looping,
+			   edge_state, edge_looping);
+	      if (pure_const_state == IPA_NEITHER)
+	        break;
+	    }
+	  if (pure_const_state == IPA_NEITHER)
+	    break;
 
-		  if (flags & ECF_LOOPING_CONST_OR_PURE)
-		    {
-		      edge_looping = true;
-		      if (dump_file && (dump_flags & TDF_DETAILS))
-			fprintf (dump_file, " unavailable looping");
-		    }
-		  if (flags & ECF_CONST)
-		    {
-		      if (dump_file && (dump_flags & TDF_DETAILS))
-		        fprintf (dump_file, " const\n");
-		    }
-		  else if (flags & ECF_PURE)
-		    {
-		      edge_state = IPA_PURE;
-		      if (dump_file && (dump_flags & TDF_DETAILS))
-		        fprintf (dump_file, " pure\n");
-		    }
-		  else if (cgraph_edge_cannot_lead_to_return (e))
-		    {
-		      edge_state = IPA_PURE;
-		      edge_looping = true;
-		      if (dump_file && (dump_flags & TDF_DETAILS))
-		        fprintf (dump_file, " ignoring side effects->pure looping\n");
-		    }
-		  else
-		    {
-		      if (dump_file && (dump_flags & TDF_DETAILS))
-		        fprintf (dump_file, " neihter\n");
-		      edge_state = IPA_NEITHER;
-		      edge_looping = true;
-		    }
-		}
+	  /* Now process the indirect call.  */
+          for (ie = node->indirect_calls; ie; ie = ie->next_callee)
+	    {
+	      enum pure_const_state_e edge_state = IPA_CONST;
+	      bool edge_looping = false;
 
-	      /* Merge the results with what we already know.
-		 When we found function to be NEITHER, but we know
-		 it is looping pure const, be sure to set the looping flag. */
-	      pure_const_state = MAX (pure_const_state, MIN (edge_state,
-				      w_l->state_previously_known));
-	      if (edge_state > w_l->state_previously_known)
-		looping = MAX (looping, w_l->looping_previously_known);
-	      else
-		looping = MAX (looping, MIN (edge_looping,
-					     w_l->looping_previously_known));
+	      if (dump_file && (dump_flags & TDF_DETAILS))
+		fprintf (dump_file, "    Indirect call");
+	      state_from_flags (&edge_state, &edge_looping,
+			        ie->indirect_info->ecf_flags,
+			        cgraph_edge_cannot_lead_to_return (ie));
+	      /* Merge the results with what we already know.  */
+	      better_state (&edge_state, &edge_looping,
+			    w_l->state_previously_known,
+			    w_l->looping_previously_known);
+	      worse_state (&pure_const_state, &looping,
+			   edge_state, edge_looping);
 	      if (pure_const_state == IPA_NEITHER)
 	        break;
 	    }
+	  if (pure_const_state == IPA_NEITHER)
+	    break;
+
+	  /* And finally all loads and stores.  */
+	  for (i = 0; ipa_ref_list_reference_iterate (&node->ref_list, i, ref); i++)
+	    {
+	      enum pure_const_state_e ref_state = IPA_CONST;
+	      bool ref_looping = false;
+	      switch (ref->use)
+		{
+		case IPA_REF_LOAD:
+		  /* readonly reads are safe.  */
+		  if (TREE_READONLY (ipa_ref_varpool_node (ref)->decl))
+		    break;
+		  if (dump_file && (dump_flags & TDF_DETAILS))
+		    fprintf (dump_file, "    nonreadonly global var read\n");
+		  ref_state = IPA_PURE;
+		  break;
+		case IPA_REF_STORE:
+		  if (ipa_ref_cannot_lead_to_return (ref))
+		    break;
+		  ref_state = IPA_NEITHER;
+		  if (dump_file && (dump_flags & TDF_DETAILS))
+		    fprintf (dump_file, "    global var write\n");
+		  break;
+		case IPA_REF_ADDR:
+		  break;
+		}
+	      better_state (&ref_state, &ref_looping,
+			    w_l->state_previously_known,
+			    w_l->looping_previously_known);
+	      worse_state (&pure_const_state, &looping,
+			   ref_state, ref_looping);
+	      if (pure_const_state == IPA_NEITHER)
+		break;
+	    }
 	  w_info = (struct ipa_dfs_info *) w->aux;
 	  w = w_info->next_cycle;
 	}
@@ -1220,7 +1320,7 @@ propagate (void)
       w = node;
       while (w)
 	{
-	  struct cgraph_edge *e;
+	  struct cgraph_edge *e, *ie;
 	  funct_state w_l = get_function_state (w);
 
 	  if (w_l->can_throw
@@ -1247,6 +1347,9 @@ propagate (void)
 	      else if (e->can_throw_external && !TREE_NOTHROW (y->decl))
 	        can_throw = true;
 	    }
+          for (ie = node->indirect_calls; ie; ie = ie->next_callee)
+	    if (ie->can_throw_external)
+	      can_throw = true;
 	  w_info = (struct ipa_dfs_info *) w->aux;
 	  w = w_info->next_cycle;
 	}