[turbofan] Run DeadCodeElimination as part of the generic lowering phase.

This way we don't need the separate late control reduction pass over the
graph, plus we can also reduce dead code recognized by generic lowering.

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/1198923002

Cr-Commit-Position: refs/heads/master@{#29174}

src/compiler/pipeline.cc

@@ -651,20 +651,6 @@ struct EarlyControlReductionPhase {
 };
 
 
-struct LateControlReductionPhase {
-  static const char* phase_name() { return "late control reduction"; }
-  void Run(PipelineData* data, Zone* temp_zone) {
-    GraphReducer graph_reducer(temp_zone, data->graph());
-    DeadCodeElimination dce(&graph_reducer, data->graph(), data->common());
-    CommonOperatorReducer common(&graph_reducer, data->graph(), data->common(),
-                                 data->machine());
-    graph_reducer.AddReducer(&dce);
-    graph_reducer.AddReducer(&common);
-    graph_reducer.ReduceGraph();
-  }
-};
-
-
 struct EarlyGraphTrimmingPhase {
   static const char* phase_name() { return "early graph trimming"; }
   void Run(PipelineData* data, Zone* temp_zone) {
@@ -706,13 +692,20 @@ struct GenericLoweringPhase {
   static const char* phase_name() { return "generic lowering"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
-    JSGenericLowering generic(data->info()->is_typing_enabled(),
+    JSGraphReducer graph_reducer(data->jsgraph(), temp_zone);
+    DeadCodeElimination dead_code_elimination(&graph_reducer, data->graph(),
+                                              data->common());
+    CommonOperatorReducer common_reducer(&graph_reducer, data->graph(),
+                                         data->common(), data->machine());
+    JSGenericLowering generic_lowering(data->info()->is_typing_enabled(),
                                        data->jsgraph());
-    SelectLowering select(data->jsgraph()->graph(), data->jsgraph()->common());
+    SelectLowering select_lowering(data->jsgraph()->graph(),
+                                   data->jsgraph()->common());
     TailCallOptimization tco(data->common(), data->graph());
-    JSGraphReducer graph_reducer(data->jsgraph(), temp_zone);
-    AddReducer(data, &graph_reducer, &generic);
-    AddReducer(data, &graph_reducer, &select);
+    AddReducer(data, &graph_reducer, &dead_code_elimination);
+    AddReducer(data, &graph_reducer, &common_reducer);
+    AddReducer(data, &graph_reducer, &generic_lowering);
+    AddReducer(data, &graph_reducer, &select_lowering);
     // TODO(turbofan): TCO is currently limited to stubs.
     if (data->info()->IsStub()) AddReducer(data, &graph_reducer, &tco);
     graph_reducer.ReduceGraph();
@@ -1113,9 +1106,6 @@ Handle<Code> Pipeline::GenerateCode() {
     Run<ChangeLoweringPhase>();
     // TODO(jarin, rossberg): Remove UNTYPED once machine typing works.
     RunPrintAndVerify("Lowered changes", true);
-
-    Run<LateControlReductionPhase>();
-    RunPrintAndVerify("Late Control reduced");
   } else {
     if (info()->is_osr()) {
       Run<OsrDeconstructionPhase>();