Make loop assignment analysis a separate phase.

src/compiler/pipeline.cc

Index: src/compiler/pipeline.cc
diff --git a/src/compiler/pipeline.cc b/src/compiler/pipeline.cc
index c8ce77e00f5df4c6ada56254a687b4a4b6d31f3b..cb6d82d6a341fbeafa2bfd99ed3e8bc0f60c4fab 100644
--- a/src/compiler/pipeline.cc
+++ b/src/compiler/pipeline.cc
@@ -9,6 +9,7 @@
 
 #include "src/base/platform/elapsed-timer.h"
 #include "src/compiler/ast-graph-builder.h"
+#include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/basic-block-instrumentor.h"
 #include "src/compiler/change-lowering.h"
 #include "src/compiler/code-generator.h"
@@ -57,6 +58,7 @@ class PipelineData {
         graph_zone_scope_(zone_pool_),
         graph_zone_(nullptr),
         graph_(nullptr),
+        loop_assignment_(nullptr),
         machine_(nullptr),
         common_(nullptr),
         javascript_(nullptr),
@@ -134,6 +136,12 @@ class PipelineData {
   JSGraph* jsgraph() const { return jsgraph_; }
   Typer* typer() const { return typer_.get(); }
 
+  LoopAssignmentAnalysis* loop_assignment() const { return loop_assignment_; }
+  void set_loop_assignment(LoopAssignmentAnalysis* loop_assignment) {
+    DCHECK_EQ(nullptr, loop_assignment_);
+    loop_assignment_ = loop_assignment;
+  }
+
   Node* context_node() const { return context_node_; }
   void set_context_node(Node* context_node) {
     DCHECK_EQ(nullptr, context_node_);
@@ -160,6 +168,7 @@ class PipelineData {
     graph_zone_scope_.Destroy();
     graph_zone_ = nullptr;
     graph_ = nullptr;
+    loop_assignment_ = nullptr;
     machine_ = nullptr;
     common_ = nullptr;
     javascript_ = nullptr;
@@ -205,13 +214,14 @@ class PipelineData {
   bool compilation_failed_;
   Handle<Code> code_;
 
-  ZonePool::Scope graph_zone_scope_;
-  Zone* graph_zone_;
   // All objects in the following group of fields are allocated in graph_zone_.
   // They are all set to NULL when the graph_zone_ is destroyed.
+  ZonePool::Scope graph_zone_scope_;
+  Zone* graph_zone_;
   Graph* graph_;
   // TODO(dcarney): make this into a ZoneObject.
   SmartPointer<SourcePositionTable> source_positions_;
+  LoopAssignmentAnalysis* loop_assignment_;
   MachineOperatorBuilder* machine_;
   CommonOperatorBuilder* common_;
   JSOperatorBuilder* javascript_;
@@ -277,10 +287,11 @@ static SmartArrayPointer<char> GetDebugName(CompilationInfo* info) {
 
 class AstGraphBuilderWithPositions : public AstGraphBuilder {
  public:
-  explicit AstGraphBuilderWithPositions(Zone* local_zone, CompilationInfo* info,
-                                        JSGraph* jsgraph,
-                                        SourcePositionTable* source_positions)
-      : AstGraphBuilder(local_zone, info, jsgraph),
+  AstGraphBuilderWithPositions(Zone* local_zone, CompilationInfo* info,
+                               JSGraph* jsgraph,
+                               LoopAssignmentAnalysis* loop_assignment,
+                               SourcePositionTable* source_positions)
+      : AstGraphBuilder(local_zone, info, jsgraph, loop_assignment),
         source_positions_(source_positions) {}
 
   bool CreateGraph() {
@@ -337,12 +348,24 @@ void Pipeline::Run(Arg0 arg_0) {
 }
 
 
+struct LoopAssignmentAnalysisPhase {
+  static const char* phase_name() { return "loop assignment analysis"; }
+
+  void Run(PipelineData* data, Zone* temp_zone) {
+    AstLoopAssignmentAnalyzer analyzer(data->graph_zone(), data->info());
+    LoopAssignmentAnalysis* loop_assignment = analyzer.Analyze();
+    data->set_loop_assignment(loop_assignment);
+  }
+};
+
+
 struct GraphBuilderPhase {
   static const char* phase_name() { return "graph builder"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
     AstGraphBuilderWithPositions graph_builder(
-        temp_zone, data->info(), data->jsgraph(), data->source_positions());
+        temp_zone, data->info(), data->jsgraph(), data->loop_assignment(),
+        data->source_positions());
     if (graph_builder.CreateGraph()) {
       data->set_context_node(graph_builder.GetFunctionContext());
     } else {
@@ -743,6 +766,10 @@ Handle<Code> Pipeline::GenerateCode() {
 
   data.source_positions()->AddDecorator();
 
+  if (FLAG_loop_assignment_analysis) {
+    Run<LoopAssignmentAnalysisPhase>();
+  }
+
   Run<GraphBuilderPhase>();
   if (data.compilation_failed()) return Handle<Code>::null();
   RunPrintAndVerify("Initial untyped", true);