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

runtime/vm/isolate.h

Index: runtime/vm/isolate.h
diff --git a/runtime/vm/isolate.h b/runtime/vm/isolate.h
index c87b56d14dda8d4222db37798b383637e6461166..407a9f8d44256acee161098392c44cd8ccc320bd 100644
--- a/runtime/vm/isolate.h
+++ b/runtime/vm/isolate.h
@@ -26,6 +26,7 @@ class HandleScope;
 class HandleVisitor;
 class Heap;
 class ICData;
+class Instance;
 class LongJump;
 class MessageHandler;
 class Mutex;
@@ -49,30 +50,31 @@ class RawUint32x4;
 
 // Used by the deoptimization infrastructure to defer allocation of unboxed
 // objects until frame is fully rewritten and GC is safe.
-// See callers of Isolate::DeferObjectMaterialization.
-class DeferredObject {
+// Describes a stack slot that should be populated with a reference to the
+// materialized object.
+class DeferredSlot {
  public:
-  DeferredObject(RawInstance** slot, DeferredObject* next)
+  DeferredSlot(RawInstance** slot, DeferredSlot* next)
       : slot_(slot), next_(next) { }
-  virtual ~DeferredObject() { }
+  virtual ~DeferredSlot() { }
 
   RawInstance** slot() const { return slot_; }
-  DeferredObject* next() const { return next_; }
+  DeferredSlot* next() const { return next_; }
 
   virtual void Materialize() = 0;
 
  private:
   RawInstance** const slot_;
-  DeferredObject* const next_;
+  DeferredSlot* const next_;
 
-  DISALLOW_COPY_AND_ASSIGN(DeferredObject);
+  DISALLOW_COPY_AND_ASSIGN(DeferredSlot);
 };
 
 
-class DeferredDouble : public DeferredObject {
+class DeferredDouble : public DeferredSlot {
  public:
-  DeferredDouble(double value, RawInstance** slot, DeferredObject* next)
-      : DeferredObject(slot, next), value_(value) { }
+  DeferredDouble(double value, RawInstance** slot, DeferredSlot* next)
+      : DeferredSlot(slot, next), value_(value) { }
 
   virtual void Materialize();
 
@@ -85,10 +87,10 @@ class DeferredDouble : public DeferredObject {
 };
 
 
-class DeferredMint : public DeferredObject {
+class DeferredMint : public DeferredSlot {
  public:
-  DeferredMint(int64_t value, RawInstance** slot, DeferredObject* next)
-      : DeferredObject(slot, next), value_(value) { }
+  DeferredMint(int64_t value, RawInstance** slot, DeferredSlot* next)
+      : DeferredSlot(slot, next), value_(value) { }
 
   virtual void Materialize();
 
@@ -101,11 +103,11 @@ class DeferredMint : public DeferredObject {
 };
 
 
-class DeferredFloat32x4 : public DeferredObject {
+class DeferredFloat32x4 : public DeferredSlot {
  public:
   DeferredFloat32x4(simd128_value_t value, RawInstance** slot,
-                    DeferredObject* next)
-      : DeferredObject(slot, next), value_(value) { }
+                    DeferredSlot* next)
+      : DeferredSlot(slot, next), value_(value) { }
 
   virtual void Materialize();
 
@@ -118,11 +120,11 @@ class DeferredFloat32x4 : public DeferredObject {
 };
 
 
-class DeferredUint32x4 : public DeferredObject {
+class DeferredUint32x4 : public DeferredSlot {
  public:
   DeferredUint32x4(simd128_value_t value, RawInstance** slot,
-                   DeferredObject* next)
-      : DeferredObject(slot, next), value_(value) { }
+                   DeferredSlot* next)
+      : DeferredSlot(slot, next), value_(value) { }
 
   virtual void Materialize();
 
@@ -135,6 +137,86 @@ class DeferredUint32x4 : public DeferredObject {
 };
 
 
+// Describes a slot that contains a reference to an object that had its
+// allocation removed by AllocationSinking pass.
+// Object itself is described and materialized by DeferredObject.
+class DeferredObjectRef : public DeferredSlot {
+ public:
+  DeferredObjectRef(intptr_t index, RawInstance** slot, DeferredSlot* next)
+      : DeferredSlot(slot, next), index_(index) { }
+
+  virtual void Materialize();
+
+  intptr_t index() const { return index_; }
+
+ private:
+  const intptr_t index_;
+
+  DISALLOW_COPY_AND_ASSIGN(DeferredObjectRef);
+};
+
+
+// Describes an object which allocation was removed by AllocationSinking pass.
+// Arguments for materialization are stored as a part of expression stack
+// for the bottommost deoptimized frame so that GC could discover them.
+// They will be removed from the stack at the very end of deoptimization.
+class DeferredObject {
+ public:
+  DeferredObject(intptr_t field_count, intptr_t* args)
+      : field_count_(field_count),
+        args_(reinterpret_cast<RawObject**>(args)),
+        object_(NULL) { }
+
+  intptr_t ArgumentCount() const {
+    return kFieldsStartIndex + kFieldEntrySize * field_count_;
+  }
+
+  RawInstance* object();
+
+ private:
+  enum {
+    kClassIndex = 0,
+    kFieldsStartIndex = kClassIndex + 1
+  };
+
+  enum {
+    kFieldIndex = 0,
+    kValueIndex,
+    kFieldEntrySize,
+  };
+
+  // Materializes the object. Returns amount of values that were consumed
+  // and should be removed from the expression stack at the very end of
+  // deoptimization.
+  void Materialize();
+
+  RawObject* GetClass() const {
+    return args_[kClassIndex];
+  }
+
+  RawObject* GetField(intptr_t index) const {
+    return args_[kFieldsStartIndex + kFieldEntrySize * index + kFieldIndex];
+  }
+
+  RawObject* GetValue(intptr_t index) const {
+    return args_[kFieldsStartIndex + kFieldEntrySize * index + kValueIndex];
+  }
+
+  // Amount of fields that have to be initialized.
+  const intptr_t field_count_;
+
+  // Pointer to the first materialization argument on the stack.
+  // The first argument is Class of the instance to materialize followed by
+  // Field, value pairs.
+  RawObject** args_;
+
+  // Object materialized from this description.
+  const Instance* object_;
+
+  DISALLOW_COPY_AND_ASSIGN(DeferredObject);
+};
+
+
 class Isolate : public BaseIsolate {
  public:
   ~Isolate();
@@ -424,40 +506,78 @@ class Isolate : public BaseIsolate {
   }
   intptr_t deopt_frame_copy_size() const { return deopt_frame_copy_size_; }
 
+  void PrepareForDeferredMaterialization(intptr_t count) {
+    if (count > 0) {
+      deferred_objects_ = new DeferredObject*[count];
+      deferred_objects_count_ = count;
+    }
+  }
+
+  void DeleteDeferredObjects() {
+    for (intptr_t i = 0; i < deferred_objects_count_; i++) {
+      delete deferred_objects_[i];
+    }
+    delete[] deferred_objects_;
+    deferred_objects_ = NULL;
+    deferred_objects_count_ = 0;
+  }
+
+  DeferredObject* GetDeferredObject(intptr_t idx) const {
+    return deferred_objects_[idx];
+  }
+
+  void SetDeferredObjectAt(intptr_t idx, DeferredObject* object) {
+    deferred_objects_[idx] = object;
+  }
+
+  intptr_t DeferredObjectsCount() const {
+    return deferred_objects_count_;
+  }
+
+  void DeferMaterializedObjectRef(intptr_t idx, intptr_t* slot) {
+    deferred_object_refs_ = new DeferredObjectRef(
+        idx,
+        reinterpret_cast<RawInstance**>(slot),
+        deferred_object_refs_);
+  }
+
   void DeferDoubleMaterialization(double value, RawDouble** slot) {
-    deferred_objects_ = new DeferredDouble(
+    deferred_boxes_ = new DeferredDouble(
         value,
         reinterpret_cast<RawInstance**>(slot),
-        deferred_objects_);
+        deferred_boxes_);
   }
 
   void DeferMintMaterialization(int64_t value, RawMint** slot) {
-    deferred_objects_ = new DeferredMint(value,
-                                         reinterpret_cast<RawInstance**>(slot),
-                                         deferred_objects_);
+    deferred_boxes_ = new DeferredMint(
+        value,
+        reinterpret_cast<RawInstance**>(slot),
+        deferred_boxes_);
   }
 
   void DeferFloat32x4Materialization(simd128_value_t value,
                                      RawFloat32x4** slot) {
-    deferred_objects_ = new DeferredFloat32x4(
+    deferred_boxes_ = new DeferredFloat32x4(
         value,
         reinterpret_cast<RawInstance**>(slot),
-        deferred_objects_);
+        deferred_boxes_);
   }
 
   void DeferUint32x4Materialization(simd128_value_t value,
                                     RawUint32x4** slot) {
-    deferred_objects_ = new DeferredUint32x4(
+    deferred_boxes_ = new DeferredUint32x4(
         value,
         reinterpret_cast<RawInstance**>(slot),
-        deferred_objects_);
+        deferred_boxes_);
   }
 
-  DeferredObject* DetachDeferredObjects() {
-    DeferredObject* list = deferred_objects_;
-    deferred_objects_ = NULL;
-    return list;
-  }
+  // Populate all deferred slots that contain boxes for double, mint, simd
+  // values.
+  void MaterializeDeferredBoxes();
+
+  // Populate all slots containing references to objects which allocations
+  // were eliminated by AllocationSinking pass.
+  void MaterializeDeferredObjects();
 
   static char* GetStatus(const char* request);
 
@@ -511,7 +631,11 @@ class Isolate : public BaseIsolate {
   fpu_register_t* deopt_fpu_registers_copy_;
   intptr_t* deopt_frame_copy_;
   intptr_t deopt_frame_copy_size_;
-  DeferredObject* deferred_objects_;
+  DeferredSlot* deferred_boxes_;
+  DeferredSlot* deferred_object_refs_;
+
+  intptr_t deferred_objects_count_;
+  DeferredObject** deferred_objects_;
 
   // Status support.
   char* stacktrace_;