2009-04-03 Richard Guenther <rguenther@suse.de>

[thirdparty/gcc.git] / gcc / tree-tailcall.c

diff --git a/gcc/tree-tailcall.c b/gcc/tree-tailcall.c
index 061d6c95a4e74fcccd316958a4c8ef9de20b96f1..59a7694f095d3d77fd61f623c40823a12a0eabd8 100644 (file)
--- a/gcc/tree-tailcall.c
+++ b/gcc/tree-tailcall.c
@@ -136,15 +136,11 @@ suitable_for_tail_opt_p (void)
   if (cfun->stdarg)
     return false;
 
-  /* No local variable nor structure field should be call-used.  We
-     ignore any kind of memory tag, as these are not real variables.  */
-
+  /* No local variable nor structure field should be call-used.  */
   FOR_EACH_REFERENCED_VAR (var, rvi)
     {
       if (!is_global_var (var)
-         && !MTAG_P (var)
-         && (gimple_aliases_computed_p (cfun)? is_call_used (var)
-             : TREE_ADDRESSABLE (var)))
+         && is_call_used (var))
        return false;
     }
 
@@ -410,11 +406,9 @@ find_tail_calls (basic_block bb, struct tailcall **ret)
          break;
        }
 
-      /* If the statement has virtual or volatile operands, fail.  */
-      if (!ZERO_SSA_OPERANDS (stmt, (SSA_OP_VUSE | SSA_OP_VIRTUAL_DEFS))
-         || gimple_has_volatile_ops (stmt)
-         || (!gimple_aliases_computed_p (cfun)
-             && gimple_references_memory_p (stmt)))
+      /* If the statement references memory or volatile operands, fail.  */
+      if (gimple_references_memory_p (stmt)
+         || gimple_has_volatile_ops (stmt))
        return;
     }
 
@@ -914,8 +908,10 @@ tree_optimize_tail_calls_1 (bool opt_tailcalls)
 
       if (!phis_constructed)
        {
-         /* Ensure that there is only one predecessor of the block.  */
-         if (!single_pred_p (first))
+         /* Ensure that there is only one predecessor of the block
+            or if there are existing degenerate PHI nodes.  */
+         if (!single_pred_p (first)
+             || !gimple_seq_empty_p (phi_nodes (first)))
            first = split_edge (single_succ_edge (ENTRY_BLOCK_PTR));
 
          /* Copy the args if needed.  */