* doc/tm.texi.in (Cond. Exec. Macros): Rename node from this ...

[pf3gnuchains/gcc-fork.git] / gcc / tree-nrv.c

diff --git a/gcc/tree-nrv.c b/gcc/tree-nrv.c
index defa8de..8ee3b8b 100644 (file)
--- a/gcc/tree-nrv.c
+++ b/gcc/tree-nrv.c
@@ -1,5 +1,6 @@
 /* Language independent return value optimizations
-   Copyright (C) 2004, 2005, 2007, 2008, 2009 Free Software Foundation, Inc.
+   Copyright (C) 2004, 2005, 2007, 2008, 2009, 2010
+   Free Software Foundation, Inc.
 
 This file is part of GCC.
 
@@ -22,16 +23,17 @@ along with GCC; see the file COPYING3.  If not see
 #include "coretypes.h"
 #include "tm.h"
 #include "tree.h"
-#include "rtl.h"
 #include "function.h"
 #include "basic-block.h"
-#include "expr.h"
-#include "diagnostic.h"
+#include "tree-pretty-print.h"
 #include "tree-flow.h"
 #include "timevar.h"
 #include "tree-dump.h"
 #include "tree-pass.h"
 #include "langhooks.h"
+#include "flags.h"     /* For "optimize" in gate_pass_return_slot.
+                          FIXME: That should be up to the pass manager,
+                          but pass_nrv is not in pass_all_optimizations.  */
 
 /* This file implements return value optimizations for functions which
    return aggregate types.
@@ -129,6 +131,12 @@ tree_nrv (void)
   if (DECL_NAME (result))
     return 0;
 
+  /* If the result has its address taken then it might be modified
+     by means not detected in the following loop.  Bail out in this
+     case.  */
+  if (TREE_ADDRESSABLE (result))
+    return 0;
+
   /* Look through each block for assignments to the RESULT_DECL.  */
   FOR_EACH_BB (bb)
     {
@@ -178,7 +186,7 @@ tree_nrv (void)
                  || TREE_ADDRESSABLE (found)
                  || DECL_ALIGN (found) > DECL_ALIGN (result)
                  || !useless_type_conversion_p (result_type,
-                                               TREE_TYPE (found)))
+                                                TREE_TYPE (found)))
                return 0;
            }
          else if (gimple_has_lhs (stmt))
@@ -218,7 +226,7 @@ tree_nrv (void)
       DECL_ABSTRACT_ORIGIN (result) = DECL_ABSTRACT_ORIGIN (found);
     }
 
-  TREE_ADDRESSABLE (result) = TREE_ADDRESSABLE (found);
+  TREE_ADDRESSABLE (result) |= TREE_ADDRESSABLE (found);
 
   /* Now walk through the function changing all references to VAR to be
      RESULT.  */
@@ -251,6 +259,9 @@ tree_nrv (void)
        }
     }
 
+  SET_DECL_VALUE_EXPR (found, result);
+  DECL_HAS_VALUE_EXPR_P (found) = 1;
+
   /* FOUND is no longer used.  Ensure it gets removed.  */
   var_ann (found)->used = 0;
   return 0;
@@ -285,23 +296,22 @@ 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 or used 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_used (dest))
+  if (call_may_clobber_ref_p (call, dest)
+      || ref_maybe_used_by_stmt_p (call, dest))
     return false;
 
   return true;
@@ -336,12 +346,11 @@ execute_return_slot_opt (void)
              && gimple_call_lhs (stmt)
              && !gimple_call_return_slot_opt_p (stmt)
              && aggregate_value_p (TREE_TYPE (gimple_call_lhs (stmt)),
-                                   gimple_call_fndecl (stmt))
-            )
+                                   gimple_call_fndecl (stmt)))
            {
              /* 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);
            }
        }