toplev.c (warn_disabled_optimization): Declare new warning flag.

        * toplev.c (warn_disabled_optimization): Declare new warning flag.
        * flags.h (warn_disabled_optimization): Add it here.
        * gcse.c (gcse_main): Add warning when disabled.
        * invoke.texi: Document -Wdisabled-optimization

Co-Authored-By: Mark Mitchell <mark@codesourcery.com>

From-SVN: r36568

1 files changed, 6 insertions, 1 deletions

diff --git a/gcc/gcse.c b/gcc/gcse.c
index d32ddeb..ba07aa7 100644
--- a/gcc/gcse.c
+++ b/gcc/gcse.c
@@ -685,7 +685,12 @@ gcse_main (f, file)
      a couple switch statements.  So we require a relatively large number
      of basic blocks and the ratio of edges to blocks to be high.  */
   if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20)
-    return 0;
+    {
+      if (warn_disabled_optimization)
+      warning ("GCSE disabled: %d > 1000 basic blocks and %d >= 20 edges/basic block",
+               n_basic_blocks, n_edges / n_basic_blocks);
+      return 0;
+    }
 
   /* See what modes support reg/reg copy operations.  */
   if (! can_copy_init_p)