[turbofan] Reorganize the pipeline around the 2nd scheduler approach.

The JavaScript pipeline now consists of the following steps:

 1. Typed lowering.
 2. Representation selection (actually SimplifiedLowering).
 3. Early optimization pass (incl. JSGenericLowering).
 4. Effect control linearization (not for asm.js).
 5. Late optimization pass (incl. ChangeLowering).
 6. Real scheduling.

We should further cleanup the passes and restrict type and
representation information usage to appropriate parts of the pipeline.

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/1907963002

Cr-Commit-Position: refs/heads/master@{#35702}

src/compiler/pipeline.cc

@@ -771,16 +771,22 @@ struct EscapeAnalysisPhase {
   }
 };
 
-
-struct SimplifiedLoweringPhase {
-  static const char* phase_name() { return "simplified lowering"; }
+struct RepresentationSelectionPhase {
+  static const char* phase_name() { return "representation selection"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
     SimplifiedLowering lowering(data->jsgraph(), temp_zone,
                                 data->source_positions());
     lowering.LowerAllNodes();
+  }
+};
 
+struct EarlyOptimizationPhase {
+  static const char* phase_name() { return "early optimization"; }
+
+  void Run(PipelineData* data, Zone* temp_zone) {
     JSGraphReducer graph_reducer(data->jsgraph(), temp_zone);
+    JSGenericLowering generic_lowering(data->jsgraph());
     DeadCodeElimination dead_code_elimination(&graph_reducer, data->graph(),
                                               data->common());
     SimplifiedOperatorReducer simple_reducer(data->jsgraph());
@@ -790,6 +796,7 @@ struct SimplifiedLoweringPhase {
                                          data->common(), data->machine());
     AddReducer(data, &graph_reducer, &dead_code_elimination);
     AddReducer(data, &graph_reducer, &simple_reducer);
+    AddReducer(data, &graph_reducer, &generic_lowering);
     AddReducer(data, &graph_reducer, &value_numbering);
     AddReducer(data, &graph_reducer, &machine_reducer);
     AddReducer(data, &graph_reducer, &common_reducer);
@@ -797,7 +804,6 @@ struct SimplifiedLoweringPhase {
   }
 };
 
-
 struct ControlFlowOptimizationPhase {
   static const char* phase_name() { return "control flow optimization"; }
 
@@ -838,8 +844,8 @@ struct EffectControlLinearizationPhase {
   }
 };
 
-struct ChangeLoweringPhase {
-  static const char* phase_name() { return "change lowering"; }
+struct LateOptimizationPhase {
+  static const char* phase_name() { return "late optimization"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
     JSGraphReducer graph_reducer(data->jsgraph(), temp_zone);
@@ -851,12 +857,17 @@ struct ChangeLoweringPhase {
     MachineOperatorReducer machine_reducer(data->jsgraph());
     CommonOperatorReducer common_reducer(&graph_reducer, data->graph(),
                                          data->common(), data->machine());
+    SelectLowering select_lowering(data->jsgraph()->graph(),
+                                   data->jsgraph()->common());
+    TailCallOptimization tco(data->common(), data->graph());
     AddReducer(data, &graph_reducer, &dead_code_elimination);
     AddReducer(data, &graph_reducer, &simple_reducer);
     AddReducer(data, &graph_reducer, &value_numbering);
     AddReducer(data, &graph_reducer, &lowering);
     AddReducer(data, &graph_reducer, &machine_reducer);
     AddReducer(data, &graph_reducer, &common_reducer);
+    AddReducer(data, &graph_reducer, &select_lowering);
+    AddReducer(data, &graph_reducer, &tco);
     graph_reducer.ReduceGraph();
   }
 };
@@ -898,29 +909,6 @@ struct StressLoopPeelingPhase {
 };
 
 
-struct GenericLoweringPhase {
-  static const char* phase_name() { return "generic lowering"; }
-
-  void Run(PipelineData* data, Zone* temp_zone) {
-    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->jsgraph());
-    SelectLowering select_lowering(data->jsgraph()->graph(),
-                                   data->jsgraph()->common());
-    TailCallOptimization tco(data->common(), data->graph());
-    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);
-    AddReducer(data, &graph_reducer, &tco);
-    graph_reducer.ReduceGraph();
-  }
-};
-
-
 struct ComputeSchedulePhase {
   static const char* phase_name() { return "scheduling"; }
 
@@ -1284,9 +1272,13 @@ Handle<Code> Pipeline::GenerateCode() {
     RunPrintAndVerify("Escape Analysed");
   }
 
-  // Lower simplified operators and insert changes.
-  Run<SimplifiedLoweringPhase>();
-  RunPrintAndVerify("Lowered simplified");
+  // Select representations.
+  Run<RepresentationSelectionPhase>();
+  RunPrintAndVerify("Representations selected");
+
+  // Run early optimization pass.
+  Run<EarlyOptimizationPhase>();
+  RunPrintAndVerify("Early optimized");
 
   if (info()->is_effect_scheduling_enabled()) {
     // TODO(jarin) Run value numbering for the representation changes.
@@ -1304,14 +1296,9 @@ Handle<Code> Pipeline::GenerateCode() {
   }
 
   // Lower changes that have been inserted before.
-  Run<ChangeLoweringPhase>();
-  // TODO(jarin, rossberg): Remove UNTYPED once machine typing works.
-  RunPrintAndVerify("Lowered changes", true);
-
-  // Lower any remaining generic JSOperators.
-  Run<GenericLoweringPhase>();
+  Run<LateOptimizationPhase>();
   // TODO(jarin, rossberg): Remove UNTYPED once machine typing works.
-  RunPrintAndVerify("Lowered generic", true);
+  RunPrintAndVerify("Late optimized", true);
 
   Run<LateGraphTrimmingPhase>();
   // TODO(jarin, rossberg): Remove UNTYPED once machine typing works.