Revert "A simpler scheme for garbage collection of ureachable phi inputs."

runtime/vm/flow_graph.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/flow_graph.h"
 
 #include "vm/bit_vector.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/intermediate_language.h"
 #include "vm/longjump.h"
@@ skipping 33 matching lines @@
   graph_entry_->DiscoverBlocks(NULL,  // Entry block predecessor.
                                &preorder_,
                                &postorder_,
                                &parent_,
                                &assigned_vars_,
                                variable_count(),
                                num_non_copied_params());
   // Number blocks in reverse postorder.
   intptr_t block_count = postorder_.length();
   for (intptr_t i = 0; i < block_count; ++i) {
+    postorder_[i]->set_block_id(block_count - i - 1);
     reverse_postorder_.Add(postorder_[block_count - i - 1]);
   }
   // Link instructions backwards for optimized compilation.
   // TODO(zerny): The builder should do this at construction time.
   for (intptr_t i = 0; i < block_count; ++i) {
     BlockEntryInstr* entry = postorder_[i];
     Instruction* previous = entry;
     for (ForwardInstructionIterator it(entry); !it.Done(); it.Advance()) {
       Instruction* current = it.Current();
       current->set_previous(previous);
@@ skipping 725 matching lines @@
     // TODO(zerny): Support multiple exits.
     UNREACHABLE();
   }
 
   // TODO(zerny): Adjust pre/post orders.
   // TODO(zerny): Update dominator tree.
 }
 
 
 }  // namespace dart