[turbofan] put late ssa deconstruction in register allocator behind a flag

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 488 matching lines @@
 
 struct MeetRegisterConstraintsPhase {
   static const char* phase_name() { return "meet register constraints"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
     data->register_allocator()->MeetRegisterConstraints();
   }
 };
 
 
+struct ResolvePhisPhase {
+  static const char* phase_name() { return "resolve phis"; }
+
+  void Run(PipelineData* data, Zone* temp_zone) {
+    data->register_allocator()->ResolvePhis();
+  }
+};
+
+
 struct BuildLiveRangesPhase {
   static const char* phase_name() { return "build live ranges"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
     data->register_allocator()->BuildLiveRanges();
   }
 };
 
 
 struct AllocateGeneralRegistersPhase {
@@ skipping 400 matching lines @@
   SmartArrayPointer<char> debug_name;
 #ifdef DEBUG
   debug_name = GetDebugName(data->info());
 #endif
 
   ZonePool::Scope zone_scope(data->zone_pool());
   data->InitializeRegisterAllocator(zone_scope.zone(), config,
                                     debug_name.get());
 
   Run<MeetRegisterConstraintsPhase>();
+  Run<ResolvePhisPhase>();
   Run<BuildLiveRangesPhase>();
   if (FLAG_trace_turbo) {
     OFStream os(stdout);
     PrintableInstructionSequence printable = {config, data->sequence()};
     os << "----- Instruction sequence before register allocation -----\n"
        << printable;
   }
   DCHECK(!data->register_allocator()->ExistsUseWithoutDefinition());
   Run<AllocateGeneralRegistersPhase>();
   if (!data->register_allocator()->AllocationOk()) {
@@ skipping 36 matching lines @@
 }
 
 
 void Pipeline::TearDown() {
   InstructionOperand::TearDownCaches();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8