2011-06-10 Richard Guenther <rguenther@suse.de>

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

diff --git a/gcc/tree-ssa-forwprop.c b/gcc/tree-ssa-forwprop.c
index 56ba522..77a6264 100644 (file)
--- a/gcc/tree-ssa-forwprop.c
+++ b/gcc/tree-ssa-forwprop.c
@@ -2212,7 +2212,8 @@ ssa_forward_propagate_and_combine (void)
 
   FOR_EACH_BB (bb)
     {
-      gimple_stmt_iterator gsi;
+      gimple_stmt_iterator gsi, prev;
+      bool prev_initialized;
 
       /* Apply forward propagation to all stmts in the basic-block.
         Note we update GSI within the loop as necessary.  */
@@ -2304,7 +2305,8 @@ ssa_forward_propagate_and_combine (void)
 
       /* Combine stmts with the stmts defining their operands.
         Note we update GSI within the loop as necessary.  */
-      for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi);)
+      prev_initialized = false;
+      for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
        {
          gimple stmt = gsi_stmt (gsi);
          bool changed = false;
@@ -2386,9 +2388,24 @@ ssa_forward_propagate_and_combine (void)
            default:;
            }
 
-         /* If the stmt changed try combining it again.  */
-         if (!changed)
-           gsi_prev (&gsi);
+         if (changed)
+           {
+             /* If the stmt changed then re-visit it and the statements
+                inserted before it.  */
+             if (!prev_initialized)
+               gsi = gsi_start_bb (bb);
+             else
+               {
+                 gsi = prev;
+                 gsi_next (&gsi);
+               }
+           }
+         else
+           {
+             prev = gsi;
+             prev_initialized = true;
+             gsi_next (&gsi);
+           }
        }
     }