Implement fixpoint iteration for escape analysis.

src/hydrogen-escape-analysis.h

Index: src/hydrogen-escape-analysis.h
diff --git a/src/hydrogen-escape-analysis.h b/src/hydrogen-escape-analysis.h
index 2d425e2ecd692e4831cd2c802fd0e597881b3f7c..ff796866a8475baa3ef80f457998cb460d9810b2 100644
--- a/src/hydrogen-escape-analysis.h
+++ b/src/hydrogen-escape-analysis.h
@@ -40,14 +40,17 @@ class HEscapeAnalysisPhase : public HPhase {
   explicit HEscapeAnalysisPhase(HGraph* graph)
       : HPhase("H_Escape analysis", graph),
         captured_(0, zone()),
+        maybe_more_work_(true),
         number_of_objects_(0),
         number_of_values_(0),
         cumulative_values_(0),
         block_states_(graph->blocks()->length(), zone()) { }
 
   void Run() {

[titzer, 2013/08/30 11:19:29]

I would move this method into the .cc file and make the "more_work" variable
into the return value of the CollectCapturedValues() method--then you don't need
a field.

[Michael Starzinger, 2013/09/17 13:47:13]

Done. After rebasing I can just check for "captured.is_empty()", much simpler
now with the latest version.

-    CollectCapturedValues();
-    PerformScalarReplacement();
+    for (int i = 0; i < kMaxFixpointIterationCount && maybe_more_work_; i++) {
+      CollectCapturedValues();
+      PerformScalarReplacement();
+    }
   }
 
  private:
@@ -71,9 +74,15 @@ class HEscapeAnalysisPhase : public HPhase {
     block_states_.Set(block->block_id(), state);
   }
 
+  // Maximum number of escape analysis iterations.
+  static const int kMaxFixpointIterationCount = 2;
+
   // List of allocations captured during collection phase.
   ZoneList<HInstruction*> captured_;
 
+  // Indicates another iteration might discover new captured objects.
+  bool maybe_more_work_;
+
   // Number of captured objects on which scalar replacement was done.
   int number_of_objects_;