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[pf3gnuchains/gcc-fork.git] / gcc / tree-ssa-copy.c

diff --git a/gcc/tree-ssa-copy.c b/gcc/tree-ssa-copy.c
index 4b8d0b9..5c738f2 100644 (file)
--- a/gcc/tree-ssa-copy.c
+++ b/gcc/tree-ssa-copy.c
@@ -1,5 +1,6 @@
 /* Copy propagation and SSA_NAME replacement support routines.
-   Copyright (C) 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
+   Copyright (C) 2004, 2005, 2006, 2007, 2008, 2010
+   Free Software Foundation, Inc.
 
 This file is part of GCC.
 
@@ -749,6 +750,7 @@ init_copy_prop (void)
     {
       gimple_stmt_iterator si;
       int depth = bb->loop_depth;
+      bool loop_exit_p = false;
 
       for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
        {
@@ -786,6 +788,18 @@ init_copy_prop (void)
              cached_last_copy_of[SSA_NAME_VERSION (def)] = def;
        }
 
+      /* In loop-closed SSA form do not copy-propagate through
+        PHI nodes in blocks with a loop exit edge predecessor.  */
+      if (current_loops
+         && loops_state_satisfies_p (LOOP_CLOSED_SSA))
+       {
+         edge_iterator ei;
+         edge e;
+         FOR_EACH_EDGE (e, ei, bb->preds)
+           if (loop_exit_edge_p (e->src->loop_father, e))
+             loop_exit_p = true;
+       }
+
       for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))
        {
           gimple phi = gsi_stmt (si);
@@ -793,12 +807,7 @@ init_copy_prop (void)
 
          def = gimple_phi_result (phi);
          if (!is_gimple_reg (def)
-             /* In loop-closed SSA form do not copy-propagate through
-                PHI nodes.  Technically this is only needed for loop
-                exit PHIs, but this is difficult to query.  */
-             || (current_loops
-                 && gimple_phi_num_args (phi) == 1
-                 && loops_state_satisfies_p (LOOP_CLOSED_SSA)))
+             || loop_exit_p)
             prop_set_simulate_again (phi, false);
          else
             prop_set_simulate_again (phi, true);