[4.4] Backport of the fix for PR 49886 (again)

Index: gcc/testsuite/gcc.dg/torture/pr49886.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr49886.c	(revision 178885)
+++ gcc/testsuite/gcc.dg/torture/pr49886.c	(working copy)
@@ -1,5 +1,4 @@ 
 /* { dg-do run } */
-/* { dg-xfail-run-if "" { "*-*-*" } { "-O2" "-O3" "-Os" } } */
 
 struct PMC {
     unsigned flags;
Index: gcc/testsuite/gcc.dg/torture/pr50287.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr50287.c	(revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr50287.c	(revision 0)
@@ -0,0 +1,109 @@ 
+/* { dg-do compile } */
+
+struct PMC {
+    unsigned flags;
+};
+
+struct PVC {
+  unsigned flags, other_stuff;
+};
+
+
+typedef struct Pcc_cell
+{
+    struct PMC *p;
+    long bla;
+    long type;
+} Pcc_cell;
+
+int gi;
+int cond;
+
+struct PVC g_pvc;
+
+extern void abort ();
+extern void never_ever(int interp, struct PMC *pmc)
+  __attribute__((noinline,noclone));
+
+void never_ever (int interp, struct PMC *pmc)
+{
+  abort ();
+}
+
+static void mark_cell(int * interp, Pcc_cell *c, struct PVC pvc)
+  __attribute__((__nonnull__(1)));
+
+static void
+mark_cell(int * interp, Pcc_cell *c, struct PVC pvc)
+{
+  if (!cond)
+    return;
+
+  if (c && c->type == 4 && c->p
+      && !(c->p->flags & (1<<8)))
+    never_ever(gi + 1, c->p);
+  if (c && c->type == 4 && c->p
+      && !(c->p->flags & (1<<7)))
+    never_ever(gi + 2, c->p);
+  if (c && c->type == 4 && c->p
+      && !(c->p->flags & (1<<6)))
+    never_ever(gi + 3, c->p);
+  if (c && c->type == 4 && c->p
+      && !(c->p->flags & (1<<5)))
+    never_ever(gi + 4, c->p);
+  if (c && c->type == 4 && c->p
+      && !(c->p->flags & (1<<4)))
+    never_ever(gi + 5, c->p);
+  if (c && c->type == 4 && c->p
+      && !(c->p->flags & (1<<3)))
+    never_ever(gi + 6, c->p);
+  if (c && c->type == 4 && c->p
+      && !(c->p->flags & (1<<2)))
+    never_ever(gi + 7, c->p);
+  if (c && c->type == 4 && c->p
+      && !(c->p->flags & (1<<1)))
+    never_ever(gi + 8, c->p);
+  if (c && c->type == 4 && c->p
+      && !(c->p->flags & (1<<9)))
+    never_ever(gi + 9, c->p);
+}
+
+static void
+foo(int * interp, Pcc_cell *c)
+{
+  mark_cell(interp, c, g_pvc);
+}
+
+static struct Pcc_cell *
+__attribute__((noinline,noclone))
+getnull(void)
+{
+  return (struct Pcc_cell *) 0;
+}
+
+
+int main()
+{
+  int i;
+
+  cond = 1;
+  for (i = 0; i < 100; i++)
+    foo (&gi, getnull ());
+  return 0;
+}
+
+
+void
+bar_1 (int * interp, Pcc_cell *c)
+{
+  c->bla += 1;
+  mark_cell(interp, c, g_pvc);
+}
+
+void
+bar_2 (int * interp, Pcc_cell *c, struct PVC pvc)
+{
+  c->bla += 2;
+  mark_cell(interp, c, pvc);
+}
+
Index: gcc/ipa-split.c
===================================================================
--- gcc/ipa-split.c	(revision 178885)
+++ gcc/ipa-split.c	(working copy)
@@ -946,7 +946,7 @@  split_function (struct split_point *spli
   bitmap args_to_skip = BITMAP_ALLOC (NULL);
   tree parm;
   int num = 0;
-  struct cgraph_node *node;
+  struct cgraph_node *node, *cur_node = cgraph_node (current_function_decl);
   basic_block return_bb = find_return_bb ();
   basic_block call_bb;
   gimple_stmt_iterator gsi;
@@ -966,17 +966,39 @@  split_function (struct split_point *spli
       dump_split_point (dump_file, split_point);
     }
 
+  if (cur_node->local.can_change_signature
+      && !TYPE_ATTRIBUTES (TREE_TYPE (cur_node->decl)))
+    args_to_skip = BITMAP_ALLOC (NULL);
+  else
+    args_to_skip = NULL;
+
   /* Collect the parameters of new function and args_to_skip bitmap.  */
   for (parm = DECL_ARGUMENTS (current_function_decl);
        parm; parm = DECL_CHAIN (parm), num++)
-    if (!is_gimple_reg (parm)
-	|| !gimple_default_def (cfun, parm)
-	|| !bitmap_bit_p (split_point->ssa_names_to_pass,
-			  SSA_NAME_VERSION (gimple_default_def (cfun, parm))))
+    if (args_to_skip
+	&& (!is_gimple_reg (parm)
+	    || !gimple_default_def (cfun, parm)
+	    || !bitmap_bit_p (split_point->ssa_names_to_pass,
+			      SSA_NAME_VERSION (gimple_default_def (cfun,
+								    parm)))))
       bitmap_set_bit (args_to_skip, num);
     else
       {
-	arg = gimple_default_def (cfun, parm);
+	/* This parm might not have been used up to now, but is going to be
+	   used, hence register it.  */
+	add_referenced_var (parm);
+	if (is_gimple_reg (parm))
+	  {
+	    arg = gimple_default_def (cfun, parm);
+	    if (!arg)
+	      {
+		arg = make_ssa_name (parm, gimple_build_nop ());
+		set_default_def (parm, arg);
+	      }
+	  }
+	else
+	  arg = parm;
+
 	if (TYPE_MAIN_VARIANT (DECL_ARG_TYPE (parm))
 	    != TYPE_MAIN_VARIANT (TREE_TYPE (arg)))
 	  {
@@ -1057,9 +1079,7 @@  split_function (struct split_point *spli
 
   /* Now create the actual clone.  */
   rebuild_cgraph_edges ();
-  node = cgraph_function_versioning (cgraph_node (current_function_decl),
-				     NULL, NULL,
-				     args_to_skip,
+  node = cgraph_function_versioning (cur_node, NULL, NULL, args_to_skip,
 				     split_point->split_bbs,
 				     split_point->entry_bb, "part");
   /* For usual cloning it is enough to clear builtin only when signature
@@ -1070,7 +1090,7 @@  split_function (struct split_point *spli
       DECL_BUILT_IN_CLASS (node->decl) = NOT_BUILT_IN;
       DECL_FUNCTION_CODE (node->decl) = (enum built_in_function) 0;
     }
-  cgraph_node_remove_callees (cgraph_node (current_function_decl));
+  cgraph_node_remove_callees (cur_node);
   if (!split_part_return_p)
     TREE_THIS_VOLATILE (node->decl) = 1;
   if (dump_file)