2008-03-04 Uros Bizjak <ubizjak@gmail.com>

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

diff --git a/gcc/tree-ssa-loop-ch.c b/gcc/tree-ssa-loop-ch.c
index 30db10c..ff62c68 100644 (file)
--- a/gcc/tree-ssa-loop-ch.c
+++ b/gcc/tree-ssa-loop-ch.c
@@ -1,11 +1,11 @@
 /* Loop header copying on trees.
-   Copyright (C) 2004, 2005 Free Software Foundation, Inc.
+   Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
    
 This file is part of GCC.
    
 GCC is free software; you can redistribute it and/or modify it
 under the terms of the GNU General Public License as published by the
-Free Software Foundation; either version 2, or (at your option) any
+Free Software Foundation; either version 3, or (at your option) any
 later version.
    
 GCC is distributed in the hope that it will be useful, but WITHOUT
@@ -14,9 +14,8 @@ FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 for more details.
    
 You should have received a copy of the GNU General Public License
-along with GCC; see the file COPYING.  If not, write to the Free
-Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
-02110-1301, USA.  */
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
 
 #include "config.h"
 #include "system.h"
@@ -87,7 +86,7 @@ should_duplicate_loop_header_p (basic_block header, struct loop *loop,
       if (get_call_expr_in (last))
        return false;
 
-      *limit -= estimate_num_insns (last);
+      *limit -= estimate_num_insns (last, &eni_size_weights);
       if (*limit < 0)
        return false;
     }
@@ -123,7 +122,7 @@ do_while_loop_p (struct loop *loop)
 static unsigned int
 copy_loop_headers (void)
 {
-  unsigned i;
+  loop_iterator li;
   struct loop *loop;
   basic_block header;
   edge exit, entry;
@@ -133,25 +132,25 @@ copy_loop_headers (void)
 
   loop_optimizer_init (LOOPS_HAVE_PREHEADERS
                       | LOOPS_HAVE_SIMPLE_LATCHES);
-  if (!current_loops)
-    return 0;
+  if (number_of_loops () <= 1)
+    {
+      loop_optimizer_finalize ();
+      return 0;
+    }
 
 #ifdef ENABLE_CHECKING
-  verify_loop_structure (current_loops);
+  verify_loop_structure ();
 #endif
 
   bbs = XNEWVEC (basic_block, n_basic_blocks);
   copied_bbs = XNEWVEC (basic_block, n_basic_blocks);
   bbs_size = n_basic_blocks;
 
-  for (i = 1; i < current_loops->num; i++)
+  FOR_EACH_LOOP (li, loop, 0)
     {
       /* Copy at most 20 insns.  */
       int limit = 20;
 
-      loop = current_loops->parray[i];
-      if (!loop)
-       continue;
       header = loop->header;
 
       /* If the loop is already a do-while style one (either because it was
@@ -203,6 +202,38 @@ copy_loop_headers (void)
          continue;
        }
 
+      /* If the loop has the form "for (i = j; i < j + 10; i++)" then
+        this copying can introduce a case where we rely on undefined
+        signed overflow to eliminate the preheader condition, because
+        we assume that "j < j + 10" is true.  We don't want to warn
+        about that case for -Wstrict-overflow, because in general we
+        don't warn about overflow involving loops.  Prevent the
+        warning by setting TREE_NO_WARNING.  */
+      if (warn_strict_overflow > 0)
+       {
+         unsigned int i;
+
+         for (i = 0; i < n_bbs; ++i)
+           {
+             block_stmt_iterator bsi;
+
+             for (bsi = bsi_start (copied_bbs[i]);
+                  !bsi_end_p (bsi);
+                  bsi_next (&bsi))
+               {
+                 tree stmt = bsi_stmt (bsi);
+                 if (TREE_CODE (stmt) == COND_EXPR)
+                   TREE_NO_WARNING (stmt) = 1;
+                 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
+                   {
+                     tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
+                     if (COMPARISON_CLASS_P (rhs))
+                       TREE_NO_WARNING (stmt) = 1;
+                   }
+               }
+           }
+       }
+
       /* Ensure that the latch and the preheader is simple (we know that they
         are not now, since there was the loop exit condition.  */
       split_edge (loop_preheader_edge (loop));