[turbofan] Initial version of the new LoadElimination.

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 854 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, data->graph(),
-                                     data->jsgraph()->simplified());
     JSBuiltinReducer builtin_reducer(&graph_reducer, data->jsgraph());
     MaybeHandle<LiteralsArray> literals_array =
         data->info()->is_native_context_specializing()
             ? handle(data->info()->closure()->literals(), data->isolate())
             : MaybeHandle<LiteralsArray>();
     JSCreateLowering create_lowering(
         &graph_reducer, data->info()->dependencies(), data->jsgraph(),
         literals_array, temp_zone);
     JSTypedLowering::Flags typed_lowering_flags = JSTypedLowering::kNoFlags;
     if (data->info()->is_deoptimization_enabled()) {
@@ skipping 17 matching lines @@
     CheckpointElimination checkpoint_elimination(&graph_reducer);
     CommonOperatorReducer common_reducer(&graph_reducer, data->graph(),
                                          data->common(), data->machine());
     AddReducer(data, &graph_reducer, &dead_code_elimination);
     AddReducer(data, &graph_reducer, &builtin_reducer);
     if (data->info()->is_deoptimization_enabled()) {
       AddReducer(data, &graph_reducer, &create_lowering);
     }
     AddReducer(data, &graph_reducer, &typed_lowering);
     AddReducer(data, &graph_reducer, &intrinsic_lowering);
-    AddReducer(data, &graph_reducer, &load_elimination);
     AddReducer(data, &graph_reducer, &simple_reducer);
     AddReducer(data, &graph_reducer, &checkpoint_elimination);
     AddReducer(data, &graph_reducer, &common_reducer);
     graph_reducer.ReduceGraph();
   }
 };
 
 
 struct BranchEliminationPhase {
   static const char* phase_name() { return "branch condition elimination"; }
@@ skipping 109 matching lines @@
 
 struct StoreStoreEliminationPhase {
   static const char* phase_name() { return "Store-store elimination"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
     StoreStoreElimination store_store_elimination(data->jsgraph(), temp_zone);
     store_store_elimination.Run();
   }
 };
 
+struct LoadEliminationPhase {
+  static const char* phase_name() { return "load elimination"; }
+
+  void Run(PipelineData* data, Zone* temp_zone) {
+    // The memory optimizer requires the graphs to be trimmed, so trim now.
+    GraphTrimmer trimmer(temp_zone, data->graph());
+    NodeVector roots(temp_zone);
+    data->jsgraph()->GetCachedNodes(&roots);
+    trimmer.TrimGraph(roots.begin(), roots.end());
+
+    // Eliminate redundant loads.
+    LoadElimination load_elimination(data->jsgraph(), temp_zone);
+    load_elimination.Run();
+  }
+};
+
 struct MemoryOptimizationPhase {
   static const char* phase_name() { return "memory optimization"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
     // The memory optimizer requires the graphs to be trimmed, so trim now.
     GraphTrimmer trimmer(temp_zone, data->graph());
     NodeVector roots(temp_zone);
     data->jsgraph()->GetCachedNodes(&roots);
     trimmer.TrimGraph(roots.begin(), roots.end());
 
@@ skipping 383 matching lines @@
 
     if (FLAG_turbo_stress_loop_peeling) {
       Run<StressLoopPeelingPhase>();
       RunPrintAndVerify("Loop peeled");
     }
 
     if (FLAG_turbo_escape) {
       Run<EscapeAnalysisPhase>();
       RunPrintAndVerify("Escape Analysed");
     }
+
+    if (FLAG_turbo_load_elimination) {
+      Run<LoadEliminationPhase>();
+      RunPrintAndVerify("Load eliminated");
+    }
   }
 
   // Select representations. This has to run w/o the Typer decorator, because
   // we cannot compute meaningful types anyways, and the computed types might
   // even conflict with the representation/truncation logic.
   Run<RepresentationSelectionPhase>();
   RunPrintAndVerify("Representations selected", true);
 
 #ifdef DEBUG
   // From now on it is invalid to look at types on the nodes, because:
@@ skipping 374 matching lines @@
   data->DeleteRegisterAllocationZone();
 }
 
 CompilationInfo* PipelineImpl::info() const { return data_->info(); }
 
 Isolate* PipelineImpl::isolate() const { return info()->isolate(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8