Removes open arrays (e.g. data[0]) from raw objects.

runtime/vm/raw_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_RAW_OBJECT_H_
 #define VM_RAW_OBJECT_H_
 
 #include "platform/assert.h"
 #include "vm/globals.h"
 #include "vm/token.h"
@@ skipping 540 matching lines @@
     return reinterpret_cast<RawObject**>(&ptr()->instantiations_);
   }
   // The instantiations_ array remains empty for instantiated type arguments.
   RawArray* instantiations_;  // Array of paired canonical vectors:
                               // Even index: instantiator.
                               // Odd index: instantiated (without bound error).
   // Instantiations leading to bound errors do not get cached.
   RawSmi* length_;
 
   // Variable length data follows here.
-  RawAbstractType* types_[0];
+  RawAbstractType** types() {
+    const uword address_of_length = reinterpret_cast<uword>(&length_);
+    return reinterpret_cast<RawAbstractType**>(
+        address_of_length + sizeof(length_));
+  }
   RawObject** to(intptr_t length) {
-    return reinterpret_cast<RawObject**>(&ptr()->types_[length - 1]);
+    return reinterpret_cast<RawObject**>(&ptr()->types()[length - 1]);
   }
 
   friend class SnapshotReader;
 };
 
 
 class RawPatchClass : public RawObject {
  private:
   RAW_HEAP_OBJECT_IMPLEMENTATION(PatchClass);
 
@@ skipping 272 matching lines @@
   // Alive: If true, the embedded object pointers will be visited during GC.
   // This field cannot be shorter because of alignment issues on x64
   // architectures.
   intptr_t state_bits_;  // state, is_optimized, is_alive.
 
   // PC offsets for code patching.
   intptr_t entry_patch_pc_offset_;
   intptr_t patch_code_pc_offset_;
   intptr_t lazy_deopt_pc_offset_;
 
-  intptr_t dummy_alignment_;
-
   // Variable length data follows here.
-  int32_t data_[0];
+  int32_t* data() {
+    uword address_of_lazy = reinterpret_cast<uword>(&lazy_deopt_pc_offset_);

[Ivan Posva, 2014/06/16 23:02:13]

As discussed this pattern looks a bit fragile from the point of keeping size and
alignment in sync with expectations.

[zra, 2014/06/17 17:24:08]

Changed to:

const uword result = reinterpret_cast<uword>(this) + sizeof(*this);
ASSERT(Utils::IsAligned(result, sizeof(int32_t)));
return reinterpret_cast<int32_t*>(result);

With the appropriate types substituted for int32_t in other places.

+    return reinterpret_cast<int32_t*>(
+        address_of_lazy + sizeof(lazy_deopt_pc_offset_));
+  }
 
   friend class StackFrame;
   friend class MarkingVisitor;
   friend class Function;
 };
 
 
 class RawInstructions : public RawObject {
   RAW_HEAP_OBJECT_IMPLEMENTATION(Instructions);
 
   RawObject** from() {
     return reinterpret_cast<RawObject**>(&ptr()->code_);
   }
   RawCode* code_;
   RawArray* object_pool_;
   RawObject** to() {
     return reinterpret_cast<RawObject**>(&ptr()->object_pool_);
   }
   intptr_t size_;
 
   // Variable length data follows here.
-  uint8_t data_[0];
+  uint8_t* data() {
+    const uword address_of_size = reinterpret_cast<uword>(&size_);
+    return reinterpret_cast<uint8_t*>(address_of_size + sizeof(size_));
+  }
 
   // Private helper function used while visiting stack frames. The
   // code which iterates over dart frames is also called during GC and
   // is not allowed to create handles.
   static bool ContainsPC(RawObject* raw_obj, uword pc);
 
   friend class RawCode;
   friend class Code;
   friend class StackFrame;
   friend class MarkingVisitor;
   friend class Function;
 };
 
 
 class RawPcDescriptors : public RawObject {
   RAW_HEAP_OBJECT_IMPLEMENTATION(PcDescriptors);
 
   intptr_t length_;  // Number of descriptors.
 
   // Variable length data follows here.
-  intptr_t data_[0];
+  intptr_t* data() {
+    const uword address_of_length = reinterpret_cast<uword>(&length_);
+    return reinterpret_cast<intptr_t*>(address_of_length + sizeof(length_));
+  }
 
   friend class Object;
 };
 
 
 // Stackmap is an immutable representation of the layout of the stack at a
 // PC. The stack map representation consists of a bit map which marks each
 // live object index starting from the base of the frame.
 //
 // The Stackmap also consists of a link to the code object corresponding to
 // the frame which the stack map is describing.  The bit map representation
 // is optimized for dense and small bit maps, without any upper bound.
 class RawStackmap : public RawObject {
   RAW_HEAP_OBJECT_IMPLEMENTATION(Stackmap);
 
   // TODO(kmillikin): We need a small number of bits to encode the register
   // count.  Consider packing them in with the length.
   intptr_t length_;  // Length of payload, in bits.
   intptr_t register_bit_count_;  // Live register bits, included in length_.
 
   uword pc_;  // PC corresponding to this stack map representation.
 
   // Variable length data follows here (bitmap of the stack layout).
-  uint8_t data_[0];
+  uint8_t* data() {
+    const uword address_of_pc = reinterpret_cast<uword>(&pc_);
+    return reinterpret_cast<uint8_t*>(address_of_pc + sizeof(pc_));
+  }
 };
 
 
 class RawLocalVarDescriptors : public RawObject {
  public:
   enum VarInfoKind {
     kStackVar = 1,
     kContextVar,
     kContextLevel,
     kSavedEntryContext,
     kSavedCurrentContext
   };
 
   struct VarInfo {
     intptr_t index;      // Slot index on stack or in context.
     int8_t   kind;       // Entry kind of type VarInfoKind.
     int16_t  scope_id;   // Scope to which the variable belongs.
     intptr_t begin_pos;  // Token position of scope start.
     intptr_t end_pos;    // Token position of scope end.
   };
 
  private:
   RAW_HEAP_OBJECT_IMPLEMENTATION(LocalVarDescriptors);
   intptr_t length_;  // Number of descriptors.
   RawArray* names_;  // Array of [length_] variable names.
 
-  VarInfo data_[0];   // Variable info with [length_] entries.
+  // Variable info with [length_] entries.
+  VarInfo* data() {
+    const uword address_of_names = reinterpret_cast<uword>(&names_);
+    return reinterpret_cast<VarInfo*>(address_of_names + sizeof(names_));
+  }
 };
 
 
 class RawExceptionHandlers : public RawObject {
  public:
   // The index into the ExceptionHandlers table corresponds to
   // the try_index of the handler.
   struct HandlerInfo {
     intptr_t handler_pc;       // PC value of handler.
     int16_t outer_try_index;   // Try block index of enclosing try block.
     int8_t needs_stacktrace;   // True if a stacktrace is needed.
     int8_t has_catch_all;      // Catches all exceptions.
   };
+
  private:
   RAW_HEAP_OBJECT_IMPLEMENTATION(ExceptionHandlers);
 
   // Number of exception handler entries.
   intptr_t length_;
 
   // Array with [length_] entries. Each entry is an array of all handled
   // exception types.
   RawArray* handled_types_data_;
 
   // Exception handler info of length [length_].
-  HandlerInfo data_[0];
+  HandlerInfo* data() {
+    const uword address_of_htd = reinterpret_cast<uword>(&handled_types_data_);
+    return reinterpret_cast<HandlerInfo*>(
+        address_of_htd + sizeof(handled_types_data_));
+  }
 };
 
 
 // Contains an array of deoptimization commands, e.g., move a specific register
 // into a specific slot of unoptimized frame.
 class RawDeoptInfo : public RawObject {
   RAW_HEAP_OBJECT_IMPLEMENTATION(DeoptInfo);
 
   RawSmi* length_;  // Number of deoptimization commands
 
   // Variable length data follows here.
-  intptr_t data_[0];
+  intptr_t* data() {
+    const uword address_of_length = reinterpret_cast<uword>(&length_);
+    return reinterpret_cast<intptr_t*>(address_of_length + sizeof(length_));
+  }
 };
 
 
 class RawContext : public RawObject {
   RAW_HEAP_OBJECT_IMPLEMENTATION(Context);
 
   intptr_t num_variables_;
   Isolate* isolate_;
 
   RawObject** from() { return reinterpret_cast<RawObject**>(&ptr()->parent_); }
   RawContext* parent_;
 
   // Variable length data follows here.
-  RawInstance* data_[0];
+  RawInstance** data() {
+    const uword address_of_parent = reinterpret_cast<uword>(&parent_);
+    return reinterpret_cast<RawInstance**>(
+        address_of_parent + sizeof(parent_));
+  }
   RawObject** to(intptr_t num_vars) {
-    return reinterpret_cast<RawObject**>(&ptr()->data_[num_vars - 1]);
+    return reinterpret_cast<RawObject**>(&ptr()->data()[num_vars - 1]);
   }
 
   friend class SnapshotReader;
 };
 
 
 class RawContextScope : public RawObject {
   RAW_HEAP_OBJECT_IMPLEMENTATION(ContextScope);
 
   // TODO(iposva): Switch to convential enum offset based structure to avoid
   // alignment mishaps.
   struct VariableDesc {
     RawSmi* token_pos;
     RawString* name;
     RawBool* is_final;
     RawBool* is_const;
     union {
       RawAbstractType* type;
       RawInstance* value;  // iff is_const is true
     };
     RawSmi* context_index;
     RawSmi* context_level;
   };
 
   intptr_t num_variables_;
 
   // Variable length data follows here.
-  RawObject** from() { return reinterpret_cast<RawObject**>(&ptr()->data_[0]); }
-  RawObject* data_[0];
+  RawObject** from() {
+    return reinterpret_cast<RawObject**>(&ptr()->data()[0]);
+  }
+  RawObject** data() {
+    const uword address_of_nv = reinterpret_cast<uword>(&num_variables_);
+    return reinterpret_cast<RawObject**>(
+        address_of_nv + sizeof(num_variables_));
+  }
   RawObject** to(intptr_t num_vars) {
-    intptr_t data_length = num_vars * (sizeof(VariableDesc)/kWordSize);
-    return reinterpret_cast<RawObject**>(&ptr()->data_[data_length - 1]);
+    const intptr_t data_length = num_vars * (sizeof(VariableDesc)/kWordSize);
+    return reinterpret_cast<RawObject**>(&ptr()->data()[data_length - 1]);
   }
 };
 
 
 class RawICData : public RawObject {
   RAW_HEAP_OBJECT_IMPLEMENTATION(ICData);
 
   RawObject** from() {
     return reinterpret_cast<RawObject**>(&ptr()->owner_);
   }
@@ skipping 248 matching lines @@
   // object length so that the object can be traversed during GC).
   intptr_t allocated_length_;
 
   // Operational length in chunks of the bigint object, clamping can
   // cause this length to be reduced. If the signed_length_ is
   // negative then the number is negative.
   intptr_t signed_length_;
 
   // A sequence of Chunks (typedef in Bignum) representing bignum digits.
   // Bignum::Chunk chunks_[Utils::Abs(signed_length_)];
-  uint8_t data_[0];
+  uint8_t* data() {
+    const uword address_of_length = reinterpret_cast<uword>(&signed_length_);
+    return reinterpret_cast<uint8_t*>(
+        address_of_length + sizeof(signed_length_));
+  }
 
   friend class SnapshotReader;
 };
 
 
 class RawDouble : public RawNumber {
   RAW_HEAP_OBJECT_IMPLEMENTATION(Double);
 
   double value_;
 
@@ skipping 10 matching lines @@
   RawSmi* length_;
   RawSmi* hash_;
   RawObject** to() { return reinterpret_cast<RawObject**>(&ptr()->hash_); }
 };
 
 
 class RawOneByteString : public RawString {
   RAW_HEAP_OBJECT_IMPLEMENTATION(OneByteString);
 
   // Variable length data follows here.
-  uint8_t data_[0];
+  uint8_t* data() {
+    const uword address_of_hash = reinterpret_cast<uword>(&hash_);
+    return reinterpret_cast<uint8_t*>(address_of_hash + sizeof(hash_));
+  }
 
   friend class ApiMessageReader;
   friend class SnapshotReader;
 };
 
 
 class RawTwoByteString : public RawString {
   RAW_HEAP_OBJECT_IMPLEMENTATION(TwoByteString);
 
   // Variable length data follows here.
-  uint16_t data_[0];
+  uint16_t* data() {
+    const uword address_of_hash = reinterpret_cast<uword>(&hash_);
+    return reinterpret_cast<uint16_t*>(address_of_hash + sizeof(hash_));
+  }
 
   friend class SnapshotReader;
 };
 
 
 template<typename T>
 class ExternalStringData {
  public:
   ExternalStringData(const T* data, void* peer, Dart_PeerFinalizer callback) :
       data_(data), peer_(peer), callback_(callback) {
@@ skipping 43 matching lines @@
   RAW_HEAP_OBJECT_IMPLEMENTATION(Array);
 
   RawObject** from() {
     return reinterpret_cast<RawObject**>(&ptr()->type_arguments_);
   }
   RawTypeArguments* type_arguments_;
   RawSmi* length_;
   // Variable length data follows here.
   RawObject** data() {
     uword address_of_length = reinterpret_cast<uword>(&length_);
-    return reinterpret_cast<RawObject**>(address_of_length + kWordSize);
+    return reinterpret_cast<RawObject**>(address_of_length + sizeof(length_));
   }
   RawObject** to(intptr_t length) {
     return reinterpret_cast<RawObject**>(&ptr()->data()[length - 1]);
   }
 
   friend class RawCode;
   friend class RawImmutableArray;
   friend class SnapshotReader;
   friend class GrowableObjectArray;
   friend class Object;
@@ skipping 77 matching lines @@
 #error Architecture is not 32-bit or 64-bit.
 #endif  // ARCH_IS_32_BIT
 
 
 class RawTypedData : public RawInstance {
   RAW_HEAP_OBJECT_IMPLEMENTATION(TypedData);
 
  protected:
   RawObject** from() { return reinterpret_cast<RawObject**>(&ptr()->length_); }
   RawSmi* length_;
+  // Variable length data follows here.
+  uint8_t* data() {
+    uword address_of_length = reinterpret_cast<uword>(&length_);
+    return reinterpret_cast<uint8_t*>(address_of_length + sizeof(length_));
+  }
   RawObject** to() { return reinterpret_cast<RawObject**>(&ptr()->length_); }
 
-  // Variable length data follows here.
-  uint8_t data_[0];
-
   friend class Api;
   friend class Object;
   friend class Instance;
 };
 
 
 class RawExternalTypedData : public RawInstance {
   RAW_HEAP_OBJECT_IMPLEMENTATION(ExternalTypedData);
 
  protected:
@@ skipping 69 matching lines @@
   RawSmi* num_bracket_expressions_;
   RawString* pattern_;  // Pattern to be used for matching.
   RawObject** to() {
     return reinterpret_cast<RawObject**>(&ptr()->pattern_);
   }
 
   intptr_t type_;  // Uninitialized, simple or complex.
   intptr_t flags_;  // Represents global/local, case insensitive, multiline.
 
   // Variable length data follows here.
-  uint8_t data_[0];
+  uint8_t* data() {
+    const uword address_of_flags = reinterpret_cast<uword>(&flags_);
+    return reinterpret_cast<uint8_t*>(address_of_flags + sizeof(flags_));
+  }
 };
 
 
 class RawWeakProperty : public RawInstance {
   RAW_HEAP_OBJECT_IMPLEMENTATION(WeakProperty);
 
   RawObject** from() {
     return reinterpret_cast<RawObject**>(&ptr()->key_);
   }
   RawObject* key_;
@@ skipping 249 matching lines @@
   COMPILE_ASSERT(kTypedDataInt8ArrayViewCid == kTypedDataInt8ArrayCid + 14);
   COMPILE_ASSERT(kExternalTypedDataInt8ArrayCid ==
                  kTypedDataInt8ArrayViewCid + 15);
   COMPILE_ASSERT(kNullCid == kExternalTypedDataInt8ArrayCid + 14);
   return (kNullCid - kTypedDataInt8ArrayCid);
 }
 
 }  // namespace dart
 
 #endif  // VM_RAW_OBJECT_H_