Reuse the gap move resolver.

Rather than allocating a fresh gap move resolver for every parallel
move, use a single one per Lithium code generator.  This avoids always
reallocating the temporary zone-allocated lists used by the gap move
resolver.

Review URL: http://codereview.chromium.org/6128007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6270 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/lithium-codegen-arm.cc

@@ -1,4 +1,4 @@
-// Copyright 2010 the V8 project authors. All rights reserved.
+// Copyright 2011 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:
@@ -601,8 +601,8 @@ void LCodeGen::DoParallelMove(LParallelMove* move) {
   Register core_scratch = scratch0();
   bool destroys_core_scratch = false;
 
-  LGapResolver resolver(move->move_operands(), &marker_operand);
+  const ZoneList<LMoveOperands>* moves =
-  const ZoneList<LMoveOperands>* moves = resolver.ResolveInReverseOrder();
+      resolver_.Resolve(move->move_operands(), &marker_operand);
   for (int i = moves->length() - 1; i >= 0; --i) {
     LMoveOperands move = moves->at(i);
     LOperand* from = move.from();

src/arm/lithium-codegen-arm.h

@@ -1,4 +1,4 @@
-// Copyright 2010 the V8 project authors. All rights reserved.
+// Copyright 2011 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:
@@ -239,6 +239,9 @@ class LCodeGen BASE_EMBEDDED {
   // itself is emitted at the end of the generated code.
   SafepointTableBuilder safepoints_;
 
+  // Compiler from a set of parallel moves to a sequential list of moves.
+  LGapResolver resolver_;
+
   friend class LDeferredCode;
   friend class LEnvironment;
   friend class SafepointGenerator;

src/ia32/lithium-codegen-ia32.cc

@@ -1,4 +1,4 @@
-// Copyright 2010 the V8 project authors. All rights reserved.
+// Copyright 2011 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:
@@ -564,8 +564,8 @@ void LCodeGen::DoParallelMove(LParallelMove* move) {
   Register cpu_scratch = esi;
   bool destroys_cpu_scratch = false;
 
-  LGapResolver resolver(move->move_operands(), &marker_operand);
+  const ZoneList<LMoveOperands>* moves =
-  const ZoneList<LMoveOperands>* moves = resolver.ResolveInReverseOrder();
+      resolver_.Resolve(move->move_operands(), &marker_operand);
   for (int i = moves->length() - 1; i >= 0; --i) {
     LMoveOperands move = moves->at(i);
     LOperand* from = move.from();

src/ia32/lithium-codegen-ia32.h

@@ -1,4 +1,4 @@
-// Copyright 2010 the V8 project authors. All rights reserved.
+// Copyright 2011 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:
@@ -230,6 +230,9 @@ class LCodeGen BASE_EMBEDDED {
   // itself is emitted at the end of the generated code.
   SafepointTableBuilder safepoints_;
 
+  // Compiler from a set of parallel moves to a sequential list of moves.
+  LGapResolver resolver_;
+
   friend class LDeferredCode;
   friend class LEnvironment;
   friend class SafepointGenerator;

src/lithium.cc

@@ -60,23 +60,29 @@ class LGapNode: public ZoneObject {
 };
 
 
-LGapResolver::LGapResolver(const ZoneList<LMoveOperands>* moves,
+LGapResolver::LGapResolver()
-                           LOperand* marker_operand)
+    : nodes_(32),
-    : nodes_(4),
       identified_cycles_(4),
-      result_(4),
+      result_(16),
-      marker_operand_(marker_operand),
       next_visited_id_(0) {
+}
+
+
+const ZoneList<LMoveOperands>* LGapResolver::Resolve(
+    const ZoneList<LMoveOperands>* moves,
+    LOperand* marker_operand) {
+  nodes_.Rewind(0);
+  identified_cycles_.Rewind(0);
+  result_.Rewind(0);
+  next_visited_id_ = 0;
+
   for (int i = 0; i < moves->length(); ++i) {
     LMoveOperands move = moves->at(i);
     if (!move.IsRedundant()) RegisterMove(move);
   }
-}
 
-
-const ZoneList<LMoveOperands>* LGapResolver::ResolveInReverseOrder() {
   for (int i = 0; i < identified_cycles_.length(); ++i) {
-    ResolveCycle(identified_cycles_[i]);
+    ResolveCycle(identified_cycles_[i], marker_operand);
   }
 
   int unresolved_nodes;
@@ -105,20 +111,20 @@ void LGapResolver::AddResultMove(LOperand* from, LOperand* to) {
 }
 
 
-void LGapResolver::ResolveCycle(LGapNode* start) {
+void LGapResolver::ResolveCycle(LGapNode* start, LOperand* marker_operand) {
-  ZoneList<LOperand*> circle_operands(8);
+  ZoneList<LOperand*> cycle_operands(8);
-  circle_operands.Add(marker_operand_);
+  cycle_operands.Add(marker_operand);
   LGapNode* cur = start;
   do {
     cur->MarkResolved();
-    circle_operands.Add(cur->operand());
+    cycle_operands.Add(cur->operand());
     cur = cur->assigned_from();
   } while (cur != start);
-  circle_operands.Add(marker_operand_);
+  cycle_operands.Add(marker_operand);
 
-  for (int i = circle_operands.length() - 1; i > 0; --i) {
+  for (int i = cycle_operands.length() - 1; i > 0; --i) {
-    LOperand* from = circle_operands[i];
+    LOperand* from = cycle_operands[i];
-    LOperand* to = circle_operands[i - 1];
+    LOperand* to = cycle_operands[i - 1];
     AddResultMove(from, to);
   }
 }
@@ -156,7 +162,7 @@ void LGapResolver::RegisterMove(LMoveOperands move) {
     }
     ASSERT(!to->IsAssigned());
     if (CanReach(from, to)) {
-      // This introduces a circle. Save.
+      // This introduces a cycle. Save.
       identified_cycles_.Add(from);
     }
     to->set_assigned_from(from);

src/lithium.h

@@ -37,8 +37,9 @@ class LGapNode;
 
 class LGapResolver BASE_EMBEDDED {
  public:
-  LGapResolver(const ZoneList<LMoveOperands>* moves, LOperand* marker_operand);
+  LGapResolver();
-  const ZoneList<LMoveOperands>* ResolveInReverseOrder();
+  const ZoneList<LMoveOperands>* Resolve(const ZoneList<LMoveOperands>* moves,
+                                         LOperand* marker_operand);
 
  private:
   LGapNode* LookupNode(LOperand* operand);
@@ -47,14 +48,12 @@ class LGapResolver BASE_EMBEDDED {
   void RegisterMove(LMoveOperands move);
   void AddResultMove(LOperand* from, LOperand* to);
   void AddResultMove(LGapNode* from, LGapNode* to);
-  void ResolveCycle(LGapNode* start);
+  void ResolveCycle(LGapNode* start, LOperand* marker_operand);
 
   ZoneList<LGapNode*> nodes_;
   ZoneList<LGapNode*> identified_cycles_;
   ZoneList<LMoveOperands> result_;
-  LOperand* marker_operand_;
   int next_visited_id_;
-  int bailout_after_ast_id_;
 };