tree-cfgcleanup.c (cleanup_tree_cfg): Verify dominance info if it claims to be available.

	* tree-cfgcleanup.c (cleanup_tree_cfg): Verify dominance info
	if it claims to be available.
	* tree-ssa-dce.c (remove_dead_stmt): Mark cfg as altered when
	edge is redirected.
	(perform_tree_ssa_dce): Always free postdominators.

From-SVN: r124236

gcc/ChangeLog

+2007-04-27  Zdenek Dvorak  <dvorakz@suse.cz>
+
+	* tree-cfgcleanup.c (cleanup_tree_cfg): Verify dominance info
+	if it claims to be available.
+	* tree-ssa-dce.c (remove_dead_stmt): Mark cfg as altered when
+	edge is redirected.
+	(perform_tree_ssa_dce): Always free postdominators.
+
 2007-04-27  Richard Henderson  <rth@redhat.com>
 
 	* config/alpha/predicates.md (aligned_memory_operand): Mark

gcc/tree-cfgcleanup.c

@@ -615,7 +615,12 @@ cleanup_tree_cfg (void)
       calculate_dominance_info (CDI_DOMINATORS);
     }
   else
-    changed = false;
+    {
+#ifdef ENABLE_CHECKING
+      verify_dominators (CDI_DOMINATORS);
+#endif
+      changed = false;
+    }
 
   changed |= cleanup_tree_cfg_1 ();
 

gcc/tree-ssa-dce.c

@@ -607,7 +607,6 @@ remove_dead_stmt (block_stmt_iterator *i, basic_block bb)
 	 3. If the post dominator has PHI nodes we may be able to compute
 	    the right PHI args for them.
 
-
 	 In each of these cases we must remove the control statement
 	 as it may reference SSA_NAMEs which are going to be removed and
 	 we remove all but one outgoing edge from the block.  */
@@ -620,6 +619,11 @@ remove_dead_stmt (block_stmt_iterator *i, basic_block bb)
 	  /* Redirect the first edge out of BB to reach POST_DOM_BB.  */
 	  redirect_edge_and_branch (EDGE_SUCC (bb, 0), post_dom_bb);
 	  PENDING_STMT (EDGE_SUCC (bb, 0)) = NULL;
+
+	  /* It is not sufficient to set cfg_altered below during edge
+	     removal, in case BB has two successors and one of them
+	     is POST_DOM_BB.  */
+	  cfg_altered = true;
 	}
       EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
       EDGE_SUCC (bb, 0)->count = bb->count;
@@ -718,6 +722,7 @@ eliminate_unnecessary_stmts (void)
 	    }
 	}
     }
+
   return something_changed;
 }
 
@@ -837,8 +842,8 @@ perform_tree_ssa_dce (bool aggressive)
   something_changed |= eliminate_unnecessary_stmts ();
   something_changed |= cfg_altered;
 
-  if (aggressive && something_changed)
-    free_dominance_info (CDI_POST_DOMINATORS);
+  /* We do not update postdominators, so free them unconditionally.  */
+  free_dominance_info (CDI_POST_DOMINATORS);
 
   /* If we removed paths in the CFG, then we need to update
      dominators as well.  I haven't investigated the possibility