[compiler] Introduce a simple store-store elimination, disabled by default.

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"
 #include "src/base/platform/elapsed-timer.h"
+#include "src/compiler/all-nodes.h"

[Jarin, 2016/06/23 09:58:28]

You should not need to add that.

[bgeron, 2016/06/23 12:03:05]

Done.

 #include "src/compiler/ast-graph-builder.h"
 #include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/basic-block-instrumentor.h"
 #include "src/compiler/branch-elimination.h"
 #include "src/compiler/bytecode-graph-builder.h"
 #include "src/compiler/checkpoint-elimination.h"
 #include "src/compiler/code-generator.h"
 #include "src/compiler/common-operator-reducer.h"
 #include "src/compiler/control-flow-optimizer.h"
 #include "src/compiler/dead-code-elimination.h"
@@ skipping 29 matching lines @@
 #include "src/compiler/pipeline-statistics.h"
 #include "src/compiler/redundancy-elimination.h"
 #include "src/compiler/register-allocator-verifier.h"
 #include "src/compiler/register-allocator.h"
 #include "src/compiler/schedule.h"
 #include "src/compiler/scheduler.h"
 #include "src/compiler/select-lowering.h"
 #include "src/compiler/simplified-lowering.h"
 #include "src/compiler/simplified-operator-reducer.h"
 #include "src/compiler/simplified-operator.h"
+#include "src/compiler/store-store-elimination.h"
 #include "src/compiler/tail-call-optimization.h"
 #include "src/compiler/type-hint-analyzer.h"
 #include "src/compiler/typer.h"
 #include "src/compiler/value-numbering-reducer.h"
 #include "src/compiler/verifier.h"
 #include "src/compiler/zone-pool.h"
 #include "src/isolate-inl.h"
 #include "src/ostreams.h"
 #include "src/parsing/parser.h"
 #include "src/register-configuration.h"
@@ skipping 953 matching lines @@
     // Post-pass for wiring the control/effects
     // - connect allocating representation changes into the control&effect
     //   chains and lower them,
     // - get rid of the region markers,
     // - introduce effect phis and rewire effects to get SSA again.
     EffectControlLinearizer linearizer(data->jsgraph(), schedule, temp_zone);
     linearizer.Run();
   }
 };
 
+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 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 423 matching lines @@
 }
 
 bool PipelineImpl::OptimizeGraph(Linkage* linkage) {
   PipelineData* data = this->data_;
 
   data->BeginPhaseKind("block building");
 
   Run<EffectControlLinearizationPhase>();
   RunPrintAndVerify("Effect and control linearized", true);
 
+  if (FLAG_turbo_store_elimination) {
+    Run<StoreStoreEliminationPhase>();
+    RunPrintAndVerify("Store-store elimination", true);
+  }
+
   Run<BranchEliminationPhase>();
   RunPrintAndVerify("Branch conditions eliminated", true);
 
   // Optimize control flow.
   if (FLAG_turbo_cf_optimization) {
     Run<ControlFlowOptimizationPhase>();
     RunPrintAndVerify("Control flow optimized", true);
   }
 
   // Optimize memory access and allocation operations.
@@ skipping 328 matching lines @@
   data->DeleteRegisterAllocationZone();
 }
 
 CompilationInfo* PipelineImpl::info() const { return data_->info(); }
 
 Isolate* PipelineImpl::isolate() const { return info()->isolate(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8