Implement a variation of scalar replacement for non-escaping allocations.

runtime/vm/deopt_instructions.h

 // Copyright (c) 2013, 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_DEOPT_INSTRUCTIONS_H_
 #define VM_DEOPT_INSTRUCTIONS_H_
 
 #include "vm/allocation.h"
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/growable_array.h"
 #include "vm/object.h"
 
 namespace dart {
 
 class Location;
 class Value;
+class MaterializeObjectInstr;
 
 // Holds all data relevant for execution of deoptimization instructions.
 class DeoptimizationContext : public ValueObject {
  public:
   // 'to_frame_start' points to the return address just below the frame's
   // stack pointer (kPcAddressOffsetFromSp). 'num_args' is 0 if there are no
   // arguments or if there are optional arguments.
   DeoptimizationContext(intptr_t* to_frame_start,
                         intptr_t to_frame_size,
                         const Array& object_table,
@@ skipping 76 matching lines @@
     kUint32x4FpuRegister,
     kStackSlot,
     kDoubleStackSlot,
     kInt64StackSlot,
     kFloat32x4StackSlot,
     kUint32x4StackSlot,
     kPcMarker,
     kCallerFp,
     kCallerPc,
     kSuffix,
+    kMaterializedObjectRef,
+    kMaterializeObject
   };
 
   static DeoptInstr* Create(intptr_t kind_as_int, intptr_t from_index);
 
   DeoptInstr() {}
   virtual ~DeoptInstr() {}
 
   virtual const char* ToCString() const = 0;
 
   virtual void Execute(DeoptimizationContext* deopt_context,
-                       intptr_t to_index) = 0;
+                       intptr_t* to_addr) = 0;
 
   virtual DeoptInstr::Kind kind() const = 0;
 
   bool Equals(const DeoptInstr& other) const {
     return (kind() == other.kind()) && (from_index() == other.from_index());
   }
 
   // Decode the payload of a suffix command.  Return the suffix length and
   // set the output parameter info_number to the index of the shared suffix.
   static intptr_t DecodeSuffix(intptr_t from_index, intptr_t* info_number);
 
   // Get the function and return address which is encoded in this
   // kRetAfterAddress deopt instruction.
   static uword GetRetAddress(DeoptInstr* instr,
                              const Array& object_table,
                              Function* func);
 
+  // Return number of initialized fields in the object that will be
+  // materialized by kMaterializeObject instruction.
+  static intptr_t GetFieldCount(DeoptInstr* instr) {
+    ASSERT(instr->kind() == DeoptInstr::kMaterializeObject);
+    return instr->from_index();
+  }
+
  protected:
+  friend class DeoptInfoBuilder;
+
   virtual intptr_t from_index() const = 0;
 
-  friend class DeoptInfoBuilder;
-
  private:
   DISALLOW_COPY_AND_ASSIGN(DeoptInstr);
 };
 
 
 // Builds a deoptimization info table, one DeoptInfo at a time.  Call AddXXX
 // methods in the order of their target, starting wih deoptimized code
 // continuation pc and ending with the first argument of the deoptimized
 // code.  Call CreateDeoptInfo to write the accumulated instructions into
 // the heap and reset the builder's internal state for the next DeoptInfo.
 class DeoptInfoBuilder : public ValueObject {
  public:
   explicit DeoptInfoBuilder(const intptr_t num_args);
 
   // 'object_table' holds all objects referred to by DeoptInstr in
   // all DeoptInfo instances for a single Code object.
   const GrowableObjectArray& object_table() { return object_table_; }
 
   // Return address before instruction.
   void AddReturnAddress(const Function& function,
                         intptr_t deopt_id,
                         intptr_t to_index);
 
   // Copy from optimized frame to unoptimized.
   void AddCopy(Value* value, const Location& from_loc, intptr_t to_index);
   void AddPcMarker(const Function& function, intptr_t to_index);
   void AddCallerFp(intptr_t to_index);
   void AddCallerPc(intptr_t to_index);
 
+  // Add object to be materialized. Emit kMaterializeObject instruction.
+  void AddMaterialization(MaterializeObjectInstr* mat);
+
+  // For every materialized object emit instructions describing data required
+  // for materialization: class of the instance to allocate and field-value
+  // pairs for initialization.
+  // Emitted instructions are expected to follow return-address slot emitted
+  // first. This way they become a part of the bottom-most deoptimized frame
+  // and are discoverable by GC.
+  // At deoptimization they will be removed by the stub at the very end:
+  // after they were used to materialize objects.
+  // Returns the index of the next stack slot. Used for verification.
+  intptr_t EmitMaterializationArguments();
+
   RawDeoptInfo* CreateDeoptInfo();
 
+  // Mark the actual start of the frame description after all materialization
+  // instructions were emitted. Used for verification purposes.
+  void MarkFrameStart() {
+    ASSERT(frame_start_ == -1);
+    frame_start_ = instructions_.length();
+  }
+
  private:
   class TrieNode;
 
   intptr_t FindOrAddObjectInTable(const Object& obj) const;
+  intptr_t FindMaterialization(MaterializeObjectInstr* mat) const;
   intptr_t CalculateStackIndex(const Location& from_loc) const;
 
+  intptr_t FrameSize() const {
+    return instructions_.length() - frame_start_;
+  }
+
+  void AddConstant(const Object& obj, intptr_t to_index);
+
   GrowableArray<DeoptInstr*> instructions_;
   const GrowableObjectArray& object_table_;
   const intptr_t num_args_;
 
   // Used to compress entries by sharing suffixes.
   TrieNode* trie_root_;
   intptr_t current_info_number_;
 
+  intptr_t frame_start_;
+  GrowableArray<MaterializeObjectInstr*> materializations_;
+
   DISALLOW_COPY_AND_ASSIGN(DeoptInfoBuilder);
 };
 
 
 // Utilities for managing the deopt table and its entries.  The table is
 // stored in an Array in the heap.  It consists of triples of (PC offset,
 // info, reason).  Elements of each entry are stored consecutively in the
 // array.
 class DeoptTable : public AllStatic {
  public:
@@ skipping 18 matching lines @@
                        DeoptInfo* info,
                        Smi* reason);
 
  private:
   static const intptr_t kEntrySize = 3;
 };
 
 }  // namespace dart
 
 #endif  // VM_DEOPT_INSTRUCTIONS_H_