re PR tree-optimization/17749 (ICE with recursive function)

	PR tree-optimization/17749
	* tree-tailcall.c (find_tail_calls): Check that parameter is
	a gimple_reg.

From-SVN: r88689

gcc/ChangeLog

+2004-10-07  Zdenek Dvorak  <dvorakz@suse.cz>
+
+	PR tree-optimization/17749
+	* tree-tailcall.c (find_tail_calls): Check that parameter is
+	a gimple_reg.
+
 2004-10-07  Kazu Hirata  <kazu@cs.umass.edu>
 
 	* config/ia64/ia64.c: Fix a comment typo.

gcc/tree-tailcall.c

@@ -431,16 +431,28 @@ find_tail_calls (basic_block bb, struct tailcall **ret)
 	   param = TREE_CHAIN (param), args = TREE_CHAIN (args))
 	{
 	  tree arg = TREE_VALUE (args);
-	  if (param != arg
-	      /* Make sure there are no problems with copying.  Note we must
+	  if (param != arg)
+	    {
+	      /* Make sure there are no problems with copying.  The parameter
 	         have a copyable type and the two arguments must have reasonably
 	         equivalent types.  The latter requirement could be relaxed if
 	         we emitted a suitable type conversion statement.  */
-	      && (!is_gimple_reg_type (TREE_TYPE (param))
+	      if (!is_gimple_reg_type (TREE_TYPE (param))
 		  || !lang_hooks.types_compatible_p (TREE_TYPE (param),
-						     TREE_TYPE (arg))))
+						     TREE_TYPE (arg)))
+		break;
+
+	      /* The parameter should be a real operand, so that phi node
+		 created for it at the start of the function has the meaning
+		 of copying the value.  This test implies is_gimple_reg_type
+		 from the previous condition, however this one could be
+		 relaxed by being more careful with copying the new value
+		 of the parameter (emitting appropriate MODIFY_EXPR and
+		 updating the virtual operands).  */
+	      if (!is_gimple_reg (param))
 		break;
 	    }
+	}
       if (!args && !param)
 	tail_recursion = true;
     }