[turbofan] Optimize string "length" property access based on types.

src/compiler/pipeline.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/pipeline.h"
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
 
 #include "src/base/adapters.h"
@@ skipping 13 matching lines @@
 #include "src/compiler/greedy-allocator.h"
 #include "src/compiler/instruction.h"
 #include "src/compiler/instruction-selector.h"
 #include "src/compiler/js-builtin-reducer.h"
 #include "src/compiler/js-context-specialization.h"
 #include "src/compiler/js-frame-specialization.h"
 #include "src/compiler/js-generic-lowering.h"
 #include "src/compiler/js-inlining.h"
 #include "src/compiler/js-intrinsic-lowering.h"
 #include "src/compiler/js-type-feedback.h"
+#include "src/compiler/js-type-feedback-lowering.h"
 #include "src/compiler/js-typed-lowering.h"
 #include "src/compiler/jump-threading.h"
 #include "src/compiler/load-elimination.h"
 #include "src/compiler/loop-analysis.h"
 #include "src/compiler/loop-peeling.h"
 #include "src/compiler/machine-operator-reducer.h"
 #include "src/compiler/move-optimizer.h"
 #include "src/compiler/osr.h"
 #include "src/compiler/pipeline-statistics.h"
 #include "src/compiler/register-allocator.h"
@@ skipping 526 matching lines @@
 struct TypedLoweringPhase {
   static const char* phase_name() { return "typed 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());
     LoadElimination load_elimination(&graph_reducer);
     JSBuiltinReducer builtin_reducer(&graph_reducer, data->jsgraph());
     JSTypedLowering typed_lowering(&graph_reducer, data->jsgraph(), temp_zone);
+    JSTypeFeedbackLowering type_feedback_lowering(
+        &graph_reducer, data->info()->is_deoptimization_enabled()
+                            ? JSTypeFeedbackLowering::kDeoptimizationEnabled
+                            : JSTypeFeedbackLowering::kNoFlags,
+        data->jsgraph());
     JSIntrinsicLowering intrinsic_lowering(
         &graph_reducer, data->jsgraph(),
         data->info()->is_deoptimization_enabled()
             ? JSIntrinsicLowering::kDeoptimizationEnabled
             : JSIntrinsicLowering::kDeoptimizationDisabled);
     CommonOperatorReducer common_reducer(&graph_reducer, data->graph(),
                                          data->common(), data->machine());
     AddReducer(data, &graph_reducer, &dead_code_elimination);
     AddReducer(data, &graph_reducer, &builtin_reducer);
     AddReducer(data, &graph_reducer, &typed_lowering);
     AddReducer(data, &graph_reducer, &intrinsic_lowering);
+    AddReducer(data, &graph_reducer, &type_feedback_lowering);
     AddReducer(data, &graph_reducer, &load_elimination);
     AddReducer(data, &graph_reducer, &common_reducer);
     graph_reducer.ReduceGraph();
   }
 };
 
 
 struct SimplifiedLoweringPhase {
   static const char* phase_name() { return "simplified lowering"; }
 
@@ skipping 749 matching lines @@
     tcf << AsC1VRegisterAllocationData("CodeGen",
                                        data->register_allocation_data());
   }
 
   data->DeleteRegisterAllocationZone();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8