re PR tree-optimization/16864 (Segmentation fault during tree tail call elimination)

	PR tree-optimization/16864
	* tree-tailcall.c (eliminate_tail_call): Do not create phi nodes
	for ssa names without default_def.

From-SVN: r85597

gcc/ChangeLog

+2004-08-05  Zdenek Dvorak  <rakdver@atrey.karlin.mff.cuni.cz>
+
+	PR tree-optimization/16864
+	* tree-tailcall.c (eliminate_tail_call): Do not create phi nodes
+	for ssa names without default_def.
+
 2004-08-05  Richard Sandiford  <rsandifo@redhat.com>
 
 	* config/i386/i386.c (ix86_expand_prologue): If the function uses a

gcc/tree-tailcall.c

@@ -730,7 +730,17 @@ eliminate_tail_call (struct tailcall *t)
       if (!phi)
 	{
 	  tree name = var_ann (param)->default_def;
-	  tree new_name = make_ssa_name (param, SSA_NAME_DEF_STMT (name));
+	  tree new_name;
+
+	  if (!name)
+	    {
+	      /* It may happen that the tag does not have a default_def in case
+		 when all uses of it are dominated by a MUST_DEF.  This however
+		 means that it is not necessary to add a phi node for this
+		 tag.  */
+	      continue;
+	    }
+	  new_name = make_ssa_name (param, SSA_NAME_DEF_STMT (name));
 
 	  var_ann (param)->default_def = new_name;
 	  phi = create_phi_node (name, first);