re PR tree-optimization/43572 (FAIL: gfortran.dg/PR19872.f execution test; formatted read - wrong numbers)

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.

From-SVN: r158418

1 files changed, 9 insertions, 11 deletions

diff --git a/gcc/tree-nrv.c b/gcc/tree-nrv.c
index b85c5a7..c2e49d3 100644
--- a/gcc/tree-nrv.c
+++ b/gcc/tree-nrv.c
@@ -291,23 +291,21 @@ struct gimple_opt_pass pass_nrv =
    optimization, where DEST is expected to be the LHS of a modify
    expression where the RHS is a function returning an aggregate.
 
-   We search for a base VAR_DECL and look to see if it is call clobbered.
-   Note that we could do better, for example, by
-   attempting to doing points-to analysis on INDIRECT_REFs.  */
+   DEST is available if it is not clobbered by the call.  */
 
 static bool
-dest_safe_for_nrv_p (tree dest)
+dest_safe_for_nrv_p (gimple call)
 {
-  while (handled_component_p (dest))
-    dest = TREE_OPERAND (dest, 0);
+  tree dest = gimple_call_lhs (call);
 
-  if (! SSA_VAR_P (dest))
+  dest = get_base_address (dest);
+  if (! dest)
     return false;
 
   if (TREE_CODE (dest) == SSA_NAME)
-    dest = SSA_NAME_VAR (dest);
+    return true;
 
-  if (is_call_clobbered (dest))
+  if (call_may_clobber_ref_p (call, dest))
     return false;
 
   return true;
@@ -346,8 +344,8 @@ execute_return_slot_opt (void)
 	     )
 	    {
 	      /* Check if the location being assigned to is
-	         call-clobbered.  */
-	      slot_opt_p = dest_safe_for_nrv_p (gimple_call_lhs (stmt));
+	         clobbered by the call.  */
+	      slot_opt_p = dest_safe_for_nrv_p (stmt);
 	      gimple_call_set_return_slot_opt (stmt, slot_opt_p);
 	    }
 	}