re PR middle-end/17278 (8% C++ compile-time regression in comparison with 3.4.1 at -O1 optimization level)

	PR middle-end/17278
	* opts.c (decode_options): Move flag_thread_jumps from -O1 and
	higher to -O2 and higher.  Likewise for tree PRE.
	* tree-ssa-dom.c (tree_ssa_dominator_optimize): Only iterate at -O2
	and better.

From-SVN: r94325

1 files changed, 7 insertions, 4 deletions

diff --git a/gcc/opts.c b/gcc/opts.c
index 1dd9da1..b5e2930 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -481,7 +481,6 @@ decode_options (unsigned int argc, const char **argv)
   if (optimize >= 1)
     {
       flag_defer_pop = 1;
-      flag_thread_jumps = 1;
 #ifdef DELAY_SLOTS
       flag_delayed_branch = 1;
 #endif
@@ -510,14 +509,12 @@ decode_options (unsigned int argc, const char **argv)
 	     the condition is satisfied in the first iteration and therefore
 	     to eliminate it.  Jump threading handles these cases now.  */
 	  flag_tree_ch = 1;
- 
-          /* PRE tends to generate bigger code.  */
-          flag_tree_pre = 1;
 	}
     }
 
   if (optimize >= 2)
     {
+      flag_thread_jumps = 1;
       flag_crossjumping = 1;
       flag_optimize_sibling_calls = 1;
       flag_cse_follow_jumps = 1;
@@ -540,6 +537,12 @@ decode_options (unsigned int argc, const char **argv)
       flag_reorder_blocks = 1;
       flag_reorder_functions = 1;
       flag_unit_at_a_time = 1;
+
+      if (!optimize_size)
+	{
+          /* PRE tends to generate bigger code.  */
+          flag_tree_pre = 1;
+	}
     }
 
   if (optimize >= 3)