Implement fixpoint iteration for escape analysis.

src/hydrogen-escape-analysis.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 288 matching lines @@
 void HEscapeAnalysisPhase::PerformScalarReplacement() {
   for (int i = 0; i < captured_.length(); i++) {
     HAllocate* allocate = HAllocate::cast(captured_.at(i));
 
     // Compute number of scalar values and start with clean slate.
     int size_in_bytes = allocate->size()->GetInteger32Constant();
     number_of_values_ = size_in_bytes / kPointerSize;
     number_of_objects_++;
     block_states_.Clear();
 
-    // Perform actual analysis steps.
+    // Perform actual analysis step.
     AnalyzeDataFlow(allocate);
 
     cumulative_values_ += number_of_values_;
     ASSERT(allocate->HasNoUses());
     ASSERT(!allocate->IsLinked());
   }
 }
 
 
 void HEscapeAnalysisPhase::Run() {
   // TODO(mstarzinger): We disable escape analysis with OSR for now, because
   // spill slots might be uninitialized. Needs investigation.
   if (graph()->has_osr()) return;
-  CollectCapturedValues();
-  PerformScalarReplacement();
+  int max_fixpoint_iteration_count = FLAG_escape_analysis_iterations;
+  for (int i = 0; i < max_fixpoint_iteration_count; i++) {
+    CollectCapturedValues();
+    if (captured_.is_empty()) break;
+    PerformScalarReplacement();
+    captured_.Clear();
+  }
 }
 
 
 } }  // namespace v8::internal