2010-04-16 Richard Guenther <rguenther@suse.de>

	PR tree-optimization/43572
	* tree-ssa-alias.h (call_may_clobber_ref_p): Declare.
	* tree-ssa-alias.c (call_may_clobber_ref_p): Export.
	* tree-flow.h (is_call_clobbered): Remove.
	* tree-flow-inline.h (is_call_clobbered): Likewise.
	* tree-dfa.c (dump_variable): Do not dump call clobber state.
	* tree-nrv.c (dest_safe_for_nrv_p): Use the alias oracle.
	(execute_return_slot_opt): Adjust.
	* tree-tailcall.c (suitable_for_tail_opt_p): Remove
	check for call clobbered vars here.
	(find_tail_calls): Move tailcall verification to the
	proper place.

	* gcc.dg/tree-ssa/tailcall-5.c: New testcase.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@158418 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 11 insertions, 33 deletions

diff --git a/gcc/tree-tailcall.c b/gcc/tree-tailcall.c
index e0d3f4844e9..ca3dffadc75 100644
--- a/gcc/tree-tailcall.c
+++ b/gcc/tree-tailcall.c
@@ -130,32 +130,9 @@ static void find_tail_calls (basic_block, struct tailcall **);
 static bool
 suitable_for_tail_opt_p (void)
 {
-  referenced_var_iterator rvi;
-  tree var;
-
   if (cfun->stdarg)
     return false;
 
-  /* No local variable nor structure field should escape to callees.  */
-  FOR_EACH_REFERENCED_VAR (var, rvi)
-    {
-      if (!is_global_var (var)
-	  /* ???  We do not have a suitable predicate for escaping to
-	     callees.  With IPA-PTA the following might be incorrect.
-	     We want to catch
-	       foo {
-	         int i;
-		 bar (&i);
-		 foo ();
-	       }
-	     where bar might store &i somewhere and in the next
-	     recursion should not be able to tell if it got the
-	     same (with tail-recursion applied) or a different
-	     address.  */
-	  && is_call_clobbered (var))
-	return false;
-    }
-
   return true;
 }
 /* Returns false when the function is not suitable for tail call optimization
@@ -387,6 +364,8 @@ find_tail_calls (basic_block bb, struct tailcall **ret)
   tree m, a;
   basic_block abb;
   size_t idx;
+  tree var;
+  referenced_var_iterator rvi;
 
   if (!single_succ_p (bb))
     return;
@@ -442,8 +421,7 @@ find_tail_calls (basic_block bb, struct tailcall **ret)
   func = gimple_call_fndecl (call);
   if (func == current_function_decl)
     {
-      tree arg, var;
-      referenced_var_iterator rvi;
+      tree arg;
 
       for (param = DECL_ARGUMENTS (func), idx = 0;
 	   param && idx < gimple_call_num_args (call);
@@ -474,15 +452,15 @@ find_tail_calls (basic_block bb, struct tailcall **ret)
 	}
       if (idx == gimple_call_num_args (call) && !param)
 	tail_recursion = true;
+    }
 
-      /* Make sure the tail invocation of this function does not refer
-	 to local variables.  */
-      FOR_EACH_REFERENCED_VAR (var, rvi)
-	{
-	  if (!is_global_var (var)
-	      && ref_maybe_used_by_stmt_p (call, var))
-	    return;
-	}
+  /* Make sure the tail invocation of this function does not refer
+     to local variables.  */
+  FOR_EACH_REFERENCED_VAR (var, rvi)
+    {
+      if (!is_global_var (var)
+	  && ref_maybe_used_by_stmt_p (call, var))
+	return;
     }
 
   /* Now check the statements after the call.  None of them has virtual