VM: Move redundancy elimination phases into a separate file.

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/il_printer.h"
 #include "vm/intermediate_language.h"
@@ skipping 34 matching lines @@
     loop_invariant_loads_(NULL),
     guarded_fields_(parsed_function.guarded_fields()),
     deoptimize_dependent_code_(),
     deferred_prefixes_(parsed_function.deferred_prefixes()),
     captured_parameters_(new(zone()) BitVector(zone(), variable_count())),
     inlining_id_(-1) {
   DiscoverBlocks();
 }
 
 
+void FlowGraph::EnsureSSATempIndex(Definition* defn,
+                                   Definition* replacement) {
+  if ((replacement->ssa_temp_index() == -1) &&
+      (defn->ssa_temp_index() != -1)) {
+    AllocateSSAIndexes(replacement);
+  }
+}
+
+
+void FlowGraph::ReplaceCurrentInstruction(ForwardInstructionIterator* iterator,
+                                          Instruction* current,
+                                          Instruction* replacement) {
+  Definition* current_defn = current->AsDefinition();
+  if ((replacement != NULL) && (current_defn != NULL)) {
+    Definition* replacement_defn = replacement->AsDefinition();
+    ASSERT(replacement_defn != NULL);
+    current_defn->ReplaceUsesWith(replacement_defn);
+    EnsureSSATempIndex(current_defn, replacement_defn);
+
+    if (FLAG_trace_optimization) {
+      THR_Print("Replacing v%" Pd " with v%" Pd "\n",
+                current_defn->ssa_temp_index(),
+                replacement_defn->ssa_temp_index());
+    }
+  } else if (FLAG_trace_optimization) {
+    if (current_defn == NULL) {
+      THR_Print("Removing %s\n", current->DebugName());
+    } else {
+      ASSERT(!current_defn->HasUses());
+      THR_Print("Removing v%" Pd ".\n", current_defn->ssa_temp_index());
+    }
+  }
+  iterator->RemoveCurrentFromGraph();
+}
+
+
+
 void FlowGraph::AddToGuardedFields(
     ZoneGrowableArray<const Field*>* array,
     const Field* field) {
   if ((field->guarded_cid() == kDynamicCid) ||
       (field->guarded_cid() == kIllegalCid)) {
     return;
   }
   for (intptr_t j = 0; j < array->length(); j++) {
     if ((*array)[j]->raw() == field->raw()) {
       return;
@@ skipping 1326 matching lines @@
 }
 
 
 bool BlockEffects::IsSideEffectFreePath(BlockEntryInstr* from,
                                         BlockEntryInstr* to) const {
   return available_at_[to->postorder_number()]->Contains(
       from->postorder_number());
 }
 
 }  // namespace dart