[turbofan] Run context specialization, inlining and initial DCE in one pass.

This is another missing piece in the puzzle towards general inlining.
The fact that we can combine this with context specialization is a nice
bonus, and not necessarily a requirement.

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/1198193002.

Cr-Commit-Position: refs/heads/master@{#29176}

src/compiler/pipeline.cc

@@ -486,27 +486,25 @@ struct GraphBuilderPhase {
 };
 
 
-struct ContextSpecializerPhase {
-  static const char* phase_name() { return "context specializing"; }
-
-  void Run(PipelineData* data, Zone* temp_zone) {
-    JSGraphReducer graph_reducer(data->jsgraph(), temp_zone);
-    JSContextSpecializer spec(&graph_reducer, data->jsgraph());
-    AddReducer(data, &graph_reducer, &spec);
-    graph_reducer.ReduceGraph();
-  }
-};
-
-
 struct InliningPhase {
   static const char* phase_name() { return "inlining"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
     JSGraphReducer graph_reducer(data->jsgraph(), temp_zone);
+    DeadCodeElimination dead_code_elimination(&graph_reducer, data->graph(),
+                                              data->common());
+    CommonOperatorReducer common_reducer(&graph_reducer, data->graph(),
+                                         data->common(), data->machine());
+    JSContextSpecializer context_specializer(&graph_reducer, data->jsgraph());
     JSInliner inliner(&graph_reducer, data->info()->is_inlining_enabled()
                                           ? JSInliner::kGeneralInlining
                                           : JSInliner::kRestrictedInlining,
                       temp_zone, data->info(), data->jsgraph());
+    AddReducer(data, &graph_reducer, &dead_code_elimination);
+    AddReducer(data, &graph_reducer, &common_reducer);
+    if (data->info()->is_context_specializing()) {
+      AddReducer(data, &graph_reducer, &context_specializer);
+    }
     AddReducer(data, &graph_reducer, &inliner);
     graph_reducer.ReduceGraph();
   }
@@ -637,8 +635,8 @@ struct ChangeLoweringPhase {
 };
 
 
-struct EarlyControlReductionPhase {
-  static const char* phase_name() { return "early control reduction"; }
+struct LateControlReductionPhase {
+  static const char* phase_name() { return "late control reduction"; }
   void Run(PipelineData* data, Zone* temp_zone) {
     GraphReducer graph_reducer(temp_zone, data->graph());
     DeadCodeElimination dce(&graph_reducer, data->graph(), data->common());
@@ -1039,18 +1037,11 @@ Handle<Code> Pipeline::GenerateCode() {
   if (data.compilation_failed()) return Handle<Code>::null();
   RunPrintAndVerify("Initial untyped", true);
 
-  Run<EarlyControlReductionPhase>();
-  RunPrintAndVerify("Early Control reduced", true);
-
-  if (info()->is_context_specializing()) {
-    // Specialize the code to the context as aggressively as possible.
-    Run<ContextSpecializerPhase>();
-    RunPrintAndVerify("Context specialized", true);
-  }
-
+  // Perform context specialization and inlining (if enabled).
   Run<InliningPhase>();
   RunPrintAndVerify("Inlined", true);
 
+  // Remove dead->live edges from the graph.
   Run<EarlyGraphTrimmingPhase>();
   RunPrintAndVerify("Early trimmed", true);