[turbofan] Introduce explicit loop exits markers.

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 927 matching lines @@
 struct RepresentationSelectionPhase {
   static const char* phase_name() { return "representation selection"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
     SimplifiedLowering lowering(data->jsgraph(), temp_zone,
                                 data->source_positions());
     lowering.LowerAllNodes();
   }
 };
 
+struct LoopExitEliminationPhase {
+  static const char* phase_name() { return "loop exit elimination"; }
+
+  void Run(PipelineData* data, Zone* temp_zone) {
+    LoopPeeler::EliminateLoopExits(data->graph(), temp_zone);
+  }
+};
+
 struct EarlyOptimizationPhase {
   static const char* phase_name() { return "early optimization"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
     JSGraphReducer graph_reducer(data->jsgraph(), temp_zone);
     JSGenericLowering generic_lowering(data->jsgraph());
     DeadCodeElimination dead_code_elimination(&graph_reducer, data->graph(),
                                               data->common());
     SimplifiedOperatorReducer simple_reducer(&graph_reducer, data->jsgraph());
     RedundancyElimination redundancy_elimination(&graph_reducer, temp_zone);
@@ skipping 468 matching lines @@
                 info()->dependencies());
     Run<TyperPhase>(&typer);
     RunPrintAndVerify("Typed");
 
     data->BeginPhaseKind("lowering");
 
     // Lower JSOperators where we can determine types.
     Run<TypedLoweringPhase>();
     RunPrintAndVerify("Lowered typed");
 
+    // Eventually, loop peeling will be done here.
+    Run<LoopExitEliminationPhase>();
+    RunPrintAndVerify("Loop exits eliminated", true);
+
     if (FLAG_turbo_stress_loop_peeling) {
       Run<StressLoopPeelingPhase>();
       RunPrintAndVerify("Loop peeled");
     }
 
     if (FLAG_turbo_escape) {
       Run<EscapeAnalysisPhase>();
       RunPrintAndVerify("Escape Analysed");
     }
 
@@ skipping 385 matching lines @@
   data->DeleteRegisterAllocationZone();
 }
 
 CompilationInfo* PipelineImpl::info() const { return data_->info(); }
 
 Isolate* PipelineImpl::isolate() const { return info()->isolate(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8