Use the VM's graph builder nesting stack for loop depth and context level.

runtime/vm/flow_graph_builder.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_FLOW_GRAPH_BUILDER_H_
 #define VM_FLOW_GRAPH_BUILDER_H_
 
 #include "platform/assert.h"
 #include "platform/globals.h"
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
 #include "vm/intermediate_language.h"
 #include "vm/raw_object.h"
 
 namespace dart {
 
 class AbstractType;
 class AbstractTypeArguments;
 class Array;
 class Class;
 class Field;
 class FlowGraph;
 class LocalVariable;
 class ParsedFunction;
 class String;
 
+class NestedStatement;
+class TestGraphVisitor;
+
 // List of recognized list factories:
 // (factory-name-symbol, result-cid, fingerprint).
 // TODO(srdjan): Store the values in the snapshot instead.
 #define RECOGNIZED_LIST_FACTORY_LIST(V)                                        \
   V(_ListFactory, kArrayCid, 176587978)                                        \
   V(_GrowableListWithData, kGrowableObjectArrayCid, 264792196)                 \
   V(_GrowableListFactory, kGrowableObjectArrayCid, 1720763678)                 \
   V(_Int8ArrayFactory, kTypedDataInt8ArrayCid, 545976988)                      \
   V(_Uint8ArrayFactory, kTypedDataUint8ArrayCid, 981297074)                    \
   V(_Uint8ClampedArrayFactory, kTypedDataUint8ClampedArrayCid, 1617830104)     \
@@ skipping 61 matching lines @@
 
   Definition* JoinReturns(BlockEntryInstr** exit_block,
                           Instruction** last_instruction);
 
   FlowGraph* caller_graph_;
   Definition* call_;
   GrowableArray<Data> exits_;
 };
 
 
-class NestedStatement;
-
 // Build a flow graph from a parsed function's AST.
 class FlowGraphBuilder: public ValueObject {
  public:
   // The inlining context is NULL if not inlining.  The osr_id is the deopt
   // id of the OSR entry or Isolate::kNoDeoptId if not compiling for OSR.
   FlowGraphBuilder(ParsedFunction* parsed_function,
                    const Array& ic_data_array,
                    InlineExitCollector* exit_collector,
                    intptr_t osr_id);
 
   FlowGraph* BuildGraph();
 
   ParsedFunction* parsed_function() const { return parsed_function_; }
   const Array& ic_data_array() const { return ic_data_array_; }
 
   void Bailout(const char* reason);
 
   intptr_t AllocateBlockId() { return ++last_used_block_id_; }
   void SetInitialBlockId(intptr_t id) { last_used_block_id_ = id; }
 
-  void set_context_level(intptr_t value) { context_level_ = value; }
-  intptr_t context_level() const { return context_level_; }
+  intptr_t context_level() const;
 
   void IncrementLoopDepth() { ++loop_depth_; }
   void DecrementLoopDepth() { --loop_depth_; }
   intptr_t loop_depth() const { return loop_depth_; }
 
   // Manage the currently active try index.
   void set_try_index(intptr_t value) { try_index_ = value; }
   intptr_t try_index() const { return try_index_; }
 
   // Manage the currently active catch-handler try index.
@@ skipping 48 matching lines @@
   ParsedFunction* parsed_function_;
   const Array& ic_data_array_;
 
   const intptr_t num_copied_params_;
   const intptr_t num_non_copied_params_;
   const intptr_t num_stack_locals_;  // Does not include any parameters.
   InlineExitCollector* const exit_collector_;
   ZoneGrowableArray<const Field*>* guarded_fields_;
 
   intptr_t last_used_block_id_;
-  intptr_t context_level_;
   intptr_t try_index_;
   intptr_t catch_try_index_;
   intptr_t loop_depth_;
   GraphEntryInstr* graph_entry_;
 
   // The expression stack height.
   intptr_t temp_count_;
 
   // Outgoing argument stack height.
   intptr_t args_pushed_;
 
   // A stack of enclosing nested statements.
   NestedStatement* nesting_stack_;
 
   // The deopt id of the OSR entry or Isolate::kNoDeoptId if not compiling
   // for OSR.
   const intptr_t osr_id_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(FlowGraphBuilder);
 };
 
 
-// Base class for a stack of enclosing statements of interest (e.g.,
-// blocks (breakable) and loops (continuable)).
-class NestedStatement : public ValueObject {
- public:
-  NestedStatement(FlowGraphBuilder* owner, const SourceLabel* label)
-      : owner_(owner),
-        label_(label),
-        outer_(owner->nesting_stack_),
-        break_target_(NULL) {
-    // Push on the owner's nesting stack.
-    owner->nesting_stack_ = this;
-  }
-
-  virtual ~NestedStatement() {
-    // Pop from the owner's nesting stack.
-    ASSERT(owner_->nesting_stack_ == this);
-    owner_->nesting_stack_ = outer_;
-  }
-
-  FlowGraphBuilder* owner() const { return owner_; }
-  const SourceLabel* label() const { return label_; }
-  NestedStatement* outer() const { return outer_; }
-  JoinEntryInstr* break_target() const { return break_target_; }
-
-  virtual JoinEntryInstr* BreakTargetFor(SourceLabel* label);
-  virtual JoinEntryInstr* ContinueTargetFor(SourceLabel* label);
-
- private:
-  FlowGraphBuilder* owner_;
-  const SourceLabel* label_;
-  NestedStatement* outer_;
-
-  JoinEntryInstr* break_target_;
-};
-
-
-class TestGraphVisitor;
-
 // Translate an AstNode to a control-flow graph fragment for its effects
 // (e.g., a statement or an expression in an effect context).  Implements a
 // function from an AstNode and next temporary index to a graph fragment
 // with a single entry and at most one exit.  The fragment is represented by
 // an (entry, exit) pair of Instruction pointers:
 //
 //   - (NULL, NULL): an empty and open graph fragment
 //   - (i0, NULL): a closed graph fragment which has only non-local exits
 //   - (i0, i1): an open graph fragment
 class EffectGraphVisitor : public AstNodeVisitor {
@@ skipping 123 matching lines @@
   StrictCompareInstr* BuildStrictCompare(AstNode* left,
                                          AstNode* right,
                                          Token::Kind kind,
                                          intptr_t token_pos);
 
   virtual void BuildTypeTest(ComparisonNode* node);
   virtual void BuildTypeCast(ComparisonNode* node);
 
   bool MustSaveRestoreContext(SequenceNode* node) const;
 
-  // Moves parent context into the context register.
-  void UnchainContext();
+  // Moves the nth parent context into the context register.
+  void UnchainContexts(intptr_t n);
 
   void CloseFragment() { exit_ = NULL; }
 
   // Returns a local variable index for a temporary local that is
   // on top of the current expression stack.
   intptr_t GetCurrentTempLocalIndex() const;
 
   Value* BuildObjectAllocation(ConstructorCallNode* node);
   void BuildConstructorCall(ConstructorCallNode* node,
                             PushArgumentInstr* alloc_value);
@@ skipping 165 matching lines @@
   // Output parameters.
   GrowableArray<TargetEntryInstr**> true_successor_addresses_;
   GrowableArray<TargetEntryInstr**> false_successor_addresses_;
 
   intptr_t condition_token_pos_;
 };
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_BUILDER_H_