[turbofan] More aggressive reuse of spill slots in the register allocator.

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/platform/elapsed-timer.h"
@@ skipping 515 matching lines @@
 
 struct AllocateDoubleRegistersPhase {
   static const char* phase_name() { return "allocate double registers"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
     data->register_allocator()->AllocateDoubleRegisters();
   }
 };
 
 
+struct ReuseSpillSlotsPhase {
+  static const char* phase_name() { return "reuse spill slots"; }
+
+  void Run(PipelineData* data, Zone* temp_zone) {
+    data->register_allocator()->ReuseSpillSlots();
+  }
+};
+
+
 struct PopulatePointerMapsPhase {
   static const char* phase_name() { return "populate pointer maps"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
     data->register_allocator()->PopulatePointerMaps();
   }
 };
 
 
 struct ConnectRangesPhase {
@@ skipping 382 matching lines @@
   Run<AllocateGeneralRegistersPhase>();
   if (!data->register_allocator()->AllocationOk()) {
     data->set_compilation_failed();
     return;
   }
   Run<AllocateDoubleRegistersPhase>();
   if (!data->register_allocator()->AllocationOk()) {
     data->set_compilation_failed();
     return;
   }
+  Run<ReuseSpillSlotsPhase>();
   Run<PopulatePointerMapsPhase>();
   Run<ConnectRangesPhase>();
   Run<ResolveControlFlowPhase>();
 
   if (FLAG_trace_turbo) {
     OFStream os(stdout);
     PrintableInstructionSequence printable = {config, data->sequence()};
     os << "----- Instruction sequence after register allocation -----\n"
        << printable;
   }
@@ skipping 15 matching lines @@
 }
 
 
 void Pipeline::TearDown() {
   InstructionOperand::TearDownCaches();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8