Eliminate temporary locals for some expressions

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 "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 122 matching lines @@
   intptr_t num_non_copied_params() const {
     return num_non_copied_params_;
   }
   intptr_t num_stack_locals() const {
     return num_stack_locals_;
   }
 
   bool IsInlining() const { return (exit_collector_ != NULL); }
   InlineExitCollector* exit_collector() const { return exit_collector_; }
 
+  intptr_t args_pushed() const { return args_pushed_; }
+  void add_args_pushed(intptr_t n) { args_pushed_ += n; }
+
  private:
   intptr_t parameter_count() const {
     return num_copied_params_ + num_non_copied_params_;
   }
   intptr_t variable_count() const {
     return parameter_count() + num_stack_locals_;
   }
 
   const 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_;
 
   intptr_t last_used_block_id_;
   intptr_t context_level_;
   intptr_t last_used_try_index_;
   intptr_t try_index_;
   GraphEntryInstr* graph_entry_;
 
+  // Outgoing argument stack height.
+  intptr_t args_pushed_;
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(FlowGraphBuilder);
 };
 
 
 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
@@ skipping 136 matching lines @@
   // Moves parent context into the context register.
   void UnchainContext();
 
   void CloseFragment() { exit_ = NULL; }
   intptr_t AllocateTempIndex() { return temp_index_++; }
   void DeallocateTempIndex(intptr_t n) {
     ASSERT(temp_index_ >= n);
     temp_index_ -= n;
   }
 
+  // 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);
 
   void BuildStoreContext(const LocalVariable& variable);
   void BuildLoadContext(const LocalVariable& variable);
 
   void BuildThrowNode(ThrowNode* node);
 
   StaticCallInstr* BuildStaticNoSuchMethodCall(
       const Class& target_class,
       AstNode* receiver,
       const String& method_name,
       ArgumentListNode* method_arguments);
 
   StaticCallInstr* BuildThrowNoSuchMethodError(intptr_t token_pos,
                                                const Class& function_class,
                                                const String& function_name,
                                                int invocation_type);
 
   void BuildStaticSetter(StaticSetterNode* node, bool result_is_needed);
   Definition* BuildStoreStaticField(StoreStaticFieldNode* node,
                                     bool result_is_needed);
 
   ClosureCallInstr* BuildClosureCall(ClosureCallNode* node);
 
   Value* BuildNullValue();
 
+  // Returns true if the run-time type check can be eliminated.
+  bool CanSkipTypeCheck(intptr_t token_pos,
+                        Value* value,
+                        const AbstractType& dst_type,
+                        const String& dst_name);
+
+  void BuildLetTempExpressions(LetNode* node);
+
  private:
+  friend class TempLocalScope;  // For ReturnDefinition.
+
   // Specify a definition of the final result.  Adds the definition to
   // the graph, but normally overridden in subclasses.
   virtual void ReturnDefinition(Definition* definition) {
     Do(definition);
   }
 
- protected:
-  // Returns true if the run-time type check can be eliminated.
-  bool CanSkipTypeCheck(intptr_t token_pos,
-                        Value* value,
-                        const AbstractType& dst_type,
-                        const String& dst_name);
-
- private:
   // Shared global state.
   FlowGraphBuilder* owner_;
 
   // Input parameters.
   intptr_t temp_index_;
 
   // Output parameters.
   Instruction* entry_;
   Instruction* exit_;
 };
@@ skipping 20 matching lines @@
   virtual void VisitStoreLocalNode(StoreLocalNode* node);
   virtual void VisitStoreIndexedNode(StoreIndexedNode* node);
   virtual void VisitStoreInstanceFieldNode(StoreInstanceFieldNode* node);
   virtual void VisitInstanceSetterNode(InstanceSetterNode* node);
   virtual void VisitThrowNode(ThrowNode* node);
   virtual void VisitClosureCallNode(ClosureCallNode* node);
   virtual void VisitStaticSetterNode(StaticSetterNode* node);
   virtual void VisitStoreStaticFieldNode(StoreStaticFieldNode* node);
   virtual void VisitTypeNode(TypeNode* node);
   virtual void VisitCommaNode(CommaNode* node);
+  virtual void VisitLetNode(LetNode* node);
 
   Value* value() const { return value_; }
 
  protected:
   // Output parameters.
   Value* value_;
 
  private:
   // Helper to set the output state to return a Value.
   virtual void ReturnValue(Value* value) { value_ = value; }
@@ skipping 69 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_