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

[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

Committed: https://chromium.googlesource.com/v8/v8/+/3253b0a136983628fbae72677678a0ccc50d6ed6

[Benedikt Meurer, 2015-06-22 06:49:01]

Hey Jaro,

Next one on the path towards proper DCE. Please take a look.

Thanks,
Benedikt

[Jarin, 2015-06-22 06:53:53]

lgtm

[Benedikt Meurer, 2015-06-22 06:54:08]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-06-22 06:54:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1198193002/1

[commit-bot: I haz the power, 2015-06-22 07:15:32]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-06-22 07:15:33]

Failed to apply patch for src/compiler/pipeline.cc:
While running git apply --index -3 -p1;
  error: patch failed: src/compiler/pipeline.cc:637
  Falling back to three-way merge...
  Applied patch to 'src/compiler/pipeline.cc' with conflicts.
  U src/compiler/pipeline.cc

Patch:       src/compiler/pipeline.cc
Index: src/compiler/pipeline.cc
diff --git a/src/compiler/pipeline.cc b/src/compiler/pipeline.cc
index
3e46d6f5194bd6abc0356231c627d67d0d97691e..34b1438fefb63b40ef20d26ee42d05c465448792
100644
--- a/src/compiler/pipeline.cc
+++ b/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();
   }
@@ -637,20 +635,6 @@ struct ChangeLoweringPhase {
 };
 
 
-struct EarlyControlReductionPhase {
-  static const char* phase_name() { return "early control reduction"; }
-  void Run(PipelineData* data, Zone* temp_zone) {
-    GraphReducer graph_reducer(temp_zone, data->graph());
-    DeadCodeElimination dce(&graph_reducer, data->graph(), data->common());
-    CommonOperatorReducer common(&graph_reducer, data->graph(), data->common(),
-                                 data->machine());
-    graph_reducer.AddReducer(&dce);
-    graph_reducer.AddReducer(&common);
-    graph_reducer.ReduceGraph();
-  }
-};
-
-
 struct LateControlReductionPhase {
   static const char* phase_name() { return "late control reduction"; }
   void Run(PipelineData* data, Zone* temp_zone) {
@@ -1046,18 +1030,11 @@ 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);

[Benedikt Meurer, 2015-06-22 07:39:10]

The CQ bit was checked by bmeurer@chromium.org

[Benedikt Meurer, 2015-06-22 07:39:10]

The patchset sent to the CQ was uploaded after l-g-t-m from jarin@chromium.org
Link to the patchset: https://codereview.chromium.org/1198193002/#ps20001
(title: "REBASE")

[commit-bot: I haz the power, 2015-06-22 07:39:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1198193002/20001

[Benedikt Meurer, 2015-06-22 08:14:10]

The CQ bit was unchecked by bmeurer@chromium.org

[Benedikt Meurer, 2015-06-22 08:14:51]

Committed patchset #2 (id:20001) manually as
3253b0a136983628fbae72677678a0ccc50d6ed6 (presubmit successful).