Reduce size of PCDescriptors. Order struct fields so that they do not get padded unnecessarily.

runtime/vm/object.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_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include <limits>
 #include "include/dart_api.h"
 #include "platform/assert.h"
@@ skipping 2956 matching lines @@
 
   static RawLocalVarDescriptors* New(intptr_t num_variables);
 
  private:
   FINAL_HEAP_OBJECT_IMPLEMENTATION(LocalVarDescriptors, Object);
   friend class Class;
 };
 
 
 class PcDescriptors : public Object {
- private:
-  // Describes the layout of PC descriptor data.
-  enum {
-    kPcEntry = 0,      // PC value of the descriptor, unique.
-    kKindEntry = 1,
-    kDeoptIdEntry = 2,      // Deopt id.
-    kTokenPosEntry = 3,     // Token position in source.
-    kTryIndexEntry = 4,     // Try block index.
-    // We would potentially be adding other objects here like
-    // pointer maps for optimized functions, local variables information  etc.
-    kNumberOfEntries = 5,
-  };
-
  public:
   enum Kind {
     kDeopt,            // Deoptimization continuation point.
     kIcCall,           // IC call.
     kOptStaticCall,    // Call directly to known target, e.g. static call.
     kUnoptStaticCall,  // Call to a known target via a stub.
     kClosureCall,      // Closure call.
     kRuntimeCall,      // Runtime call.
     kOsrEntry,         // OSR entry point in unoptimized code.
     kOther
   };
 
   intptr_t Length() const;
 
-  uword PC(intptr_t index) const;
-  PcDescriptors::Kind DescriptorKind(intptr_t index) const;
+  uword PC(intptr_t index) const {
+    ASSERT(index < Length());
+    return raw_ptr()->data()[index].pc;
+  }
+  PcDescriptors::Kind DescriptorKind(intptr_t index) const {
+    ASSERT(index < Length());
+    return static_cast<PcDescriptors::Kind>(raw_ptr()->data()[index].kind);
+  }
+  intptr_t DeoptId(intptr_t index) const {
+    ASSERT(index < Length());
+    return raw_ptr()->data()[index].deopt_id;
+  }
+  intptr_t TokenPos(intptr_t index) const {
+    ASSERT(index < Length());
+    return raw_ptr()->data()[index].token_pos;
+  }
+  intptr_t TryIndex(intptr_t index) const {
+    ASSERT(index < Length());
+    return raw_ptr()->data()[index].try_index;
+  }
   const char* KindAsStr(intptr_t index) const;
-  intptr_t DeoptId(intptr_t index) const;
-  intptr_t TokenPos(intptr_t index) const;
-  intptr_t TryIndex(intptr_t index) const;
 
   void AddDescriptor(intptr_t index,
                      uword pc,
                      PcDescriptors::Kind kind,
-                     intptr_t deopt_id,
-                     intptr_t token_pos,  // Or deopt reason.
+                     int64_t deopt_id,
+                     int64_t token_pos,  // Or deopt reason.

[siva, 2014/06/25 21:44:33]

Why is the signature changed to int64_t instead of int32_t ?

                      intptr_t try_index) const {  // Or deopt index.

[siva, 2014/06/25 21:44:33]

Why not change this to int16_t

-    SetPC(index, pc);
-    SetKind(index, kind);
-    SetDeoptId(index, deopt_id);
-    SetTokenPos(index, token_pos);
-    SetTryIndex(index, try_index);
+    RawPcDescriptors::PcDescriptorRec* rec = &raw_ptr()->data()[index];
+    rec->pc = pc;
+    rec->kind = kind;
+    ASSERT(Utils::IsInt(32, deopt_id));
+    rec->deopt_id = deopt_id;
+    ASSERT(Utils::IsInt(32, token_pos));
+    rec->token_pos = token_pos;
+    ASSERT(Utils::IsInt(16, try_index));
+    rec->try_index = try_index;
   }
 
-  static const intptr_t kBytesPerElement = (kNumberOfEntries * kWordSize);
+  static const intptr_t kBytesPerElement =
+      sizeof(RawPcDescriptors::PcDescriptorRec);
   static const intptr_t kMaxElements = kSmiMax / kBytesPerElement;
 
   static intptr_t InstanceSize() {
     ASSERT(sizeof(RawPcDescriptors) ==
            OFFSET_OF_RETURNED_VALUE(RawPcDescriptors, data));
     return 0;
   }
   static intptr_t InstanceSize(intptr_t len) {
     ASSERT(0 <= len && len <= kMaxElements);
     return RoundedAllocationSize(
         sizeof(RawPcDescriptors) + (len * kBytesPerElement));
   }
 
   static RawPcDescriptors* New(intptr_t num_descriptors);
 
   // Returns 0 if not found.
   uword GetPcForKind(Kind kind) const;
 
   // Verify (assert) assumptions about pc descriptors in debug mode.
   void Verify(const Function& function) const;
 
   static void PrintHeaderString();
 
   void PrintToJSONObject(JSONObject* jsobj) const;
 
   // We would have a VisitPointers function here to traverse the
   // pc descriptors table to visit objects if any in the table.
 
  private:
-  void SetPC(intptr_t index, uword value) const;
-  void SetKind(intptr_t index, PcDescriptors::Kind kind) const;
-  void SetDeoptId(intptr_t index, intptr_t value) const;
-  void SetTokenPos(intptr_t index, intptr_t value) const;
-  void SetTryIndex(intptr_t index, intptr_t value) const;
-
   void SetLength(intptr_t value) const;
 
-  intptr_t* EntryAddr(intptr_t index, intptr_t entry_offset) const {
-    ASSERT((index >=0) && (index < Length()));
-    intptr_t data_index = (index * kNumberOfEntries) + entry_offset;
-    return &raw_ptr()->data()[data_index];
-  }
-  RawSmi** SmiAddr(intptr_t index, intptr_t entry_offset) const {
-    return reinterpret_cast<RawSmi**>(EntryAddr(index, entry_offset));
-  }
-
   FINAL_HEAP_OBJECT_IMPLEMENTATION(PcDescriptors, Object);
   friend class Class;
   friend class Object;
 };
 
 
 class Stackmap : public Object {
  public:
   static const intptr_t kNoMaximum = -1;
   static const intptr_t kNoMinimum = -1;
@@ skipping 4055 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_