Run ControlReducer early after graph building, then again later.

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"
 #include "src/compiler/ast-graph-builder.h"
 #include "src/compiler/basic-block-instrumentor.h"
 #include "src/compiler/change-lowering.h"
 #include "src/compiler/code-generator.h"
 #include "src/compiler/control-reducer.h"
 #include "src/compiler/graph-replay.h"
 #include "src/compiler/graph-visualizer.h"
 #include "src/compiler/instruction.h"
 #include "src/compiler/instruction-selector.h"
 #include "src/compiler/js-context-specialization.h"
 #include "src/compiler/js-generic-lowering.h"
 #include "src/compiler/js-inlining.h"
 #include "src/compiler/js-typed-lowering.h"
 #include "src/compiler/machine-operator-reducer.h"
-#include "src/compiler/phi-reducer.h"
 #include "src/compiler/pipeline-statistics.h"
 #include "src/compiler/register-allocator.h"
 #include "src/compiler/schedule.h"
 #include "src/compiler/scheduler.h"
 #include "src/compiler/simplified-lowering.h"
 #include "src/compiler/simplified-operator-reducer.h"
 #include "src/compiler/typer.h"
 #include "src/compiler/value-numbering-reducer.h"
 #include "src/compiler/verifier.h"
 #include "src/compiler/zone-pool.h"
@@ skipping 280 matching lines @@
 
   Node* context_node;
   {
     PhaseScope phase_scope(pipeline_statistics.get(), "graph builder");
     ZonePool::Scope zone_scope(data.zone_pool());
     AstGraphBuilderWithPositions graph_builder(
         zone_scope.zone(), info(), data.jsgraph(), data.source_positions());
     graph_builder.CreateGraph();
     context_node = graph_builder.GetFunctionContext();
   }
-  {
-    PhaseScope phase_scope(pipeline_statistics.get(), "phi reduction");
-    PhiReducer phi_reducer;
-    GraphReducer graph_reducer(data.graph());
-    graph_reducer.AddReducer(&phi_reducer);
-    graph_reducer.ReduceGraph();
-    // TODO(mstarzinger): Running reducer once ought to be enough for everyone.
-    graph_reducer.ReduceGraph();
-    graph_reducer.ReduceGraph();
-  }
 
   VerifyAndPrintGraph(data.graph(), "Initial untyped", true);
 
+  {
+    PhaseScope phase_scope(pipeline_statistics.get(),
+                           "early control reduction");
+    SourcePositionTable::Scope pos(data.source_positions(),
+                                   SourcePosition::Unknown());
+    ZonePool::Scope zone_scope(data.zone_pool());
+    ControlReducer::ReduceGraph(zone_scope.zone(), data.jsgraph(),
+                                data.common());
+
+    VerifyAndPrintGraph(data.graph(), "Early Control reduced", true);
+  }
+
   if (info()->is_context_specializing()) {
     SourcePositionTable::Scope pos(data.source_positions(),
                                    SourcePosition::Unknown());
     // Specialize the code to the context as aggressively as possible.
     JSContextSpecializer spec(info(), data.jsgraph(), context_node);
     spec.SpecializeToContext();
     VerifyAndPrintGraph(data.graph(), "Context specialized", true);
   }
 
   if (info()->is_inlining_enabled()) {
@@ skipping 76 matching lines @@
       graph_reducer.AddReducer(&simple_reducer);
       graph_reducer.AddReducer(&lowering);
       graph_reducer.AddReducer(&mach_reducer);
       graph_reducer.ReduceGraph();
 
       // TODO(jarin, rossberg): Remove UNTYPED once machine typing works.
       VerifyAndPrintGraph(data.graph(), "Lowered changes", true);
     }
 
     {
-      PhaseScope phase_scope(pipeline_statistics.get(), "control reduction");
+      PhaseScope phase_scope(pipeline_statistics.get(),
+                             "late control reduction");
       SourcePositionTable::Scope pos(data.source_positions(),
                                      SourcePosition::Unknown());
       ZonePool::Scope zone_scope(data.zone_pool());
       ControlReducer::ReduceGraph(zone_scope.zone(), data.jsgraph(),
                                   data.common());
 
-      VerifyAndPrintGraph(data.graph(), "Control reduced");
+      VerifyAndPrintGraph(data.graph(), "Late Control reduced");
     }
   }
 
   {
     // Lower any remaining generic JSOperators.
     PhaseScope phase_scope(pipeline_statistics.get(), "generic lowering");
     SourcePositionTable::Scope pos(data.source_positions(),
                                    SourcePosition::Unknown());
     JSGenericLowering lowering(info(), data.jsgraph());
     GraphReducer graph_reducer(data.graph());
@@ skipping 170 matching lines @@
 }
 
 
 void Pipeline::TearDown() {
   InstructionOperand::TearDownCaches();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8