re PR middle-end/17278 (8% C++ compile-time regression in comparison with 3.4.1…

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

gcc/ChangeLog

+2005-01-27  Steven Bosscher  <stevenb@suse.de>
+
+	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.
+
 2005-01-27  Ian Lance Taylor  <ian@c2micro.com>
 
 	PR middle-end/19583

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)

gcc/tree-ssa-dom.c

@@ -479,7 +479,7 @@ tree_ssa_dominator_optimize (void)
 	    SSA_NAME_VALUE (name) = NULL;
 	}
     }
-  while (cfg_altered);
+  while (optimize > 1 && cfg_altered);
 
   /* Debugging dumps.  */
   if (dump_file && (dump_flags & TDF_STATS))