Double-align Zone allocations to fix MIPS issue.

runtime/vm/zone.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_ZONE_H_
 #define VM_ZONE_H_
 
 #include "platform/utils.h"
 #include "vm/allocation.h"
 #include "vm/handles.h"
@@ skipping 49 matching lines @@
 
  private:
   Zone()
     : initial_buffer_(buffer_, kInitialChunkSize),
       position_(initial_buffer_.start()),
       limit_(initial_buffer_.end()),
       head_(NULL),
       large_segments_(NULL),
       handles_(),
       previous_(NULL) {
+    ASSERT(Utils::IsAligned(position_, kAlignment));
 #ifdef DEBUG
     // Zap the entire initial buffer.
     memset(initial_buffer_.pointer(), kZapUninitializedByte,
            initial_buffer_.size());
 #endif
   }
 
   ~Zone() {  // Delete all memory associated with the zone.
 #if defined(DEBUG)
     if (FLAG_trace_zones) {
       DumpZoneSizes();
     }
 #endif
     DeleteAll();
   }
 
   // All pointers returned from AllocateUnsafe() and New() have this alignment.
-  static const intptr_t kAlignment = kWordSize;
+  static const intptr_t kAlignment = kDoubleSize;
 
   // Default initial chunk size.
   static const intptr_t kInitialChunkSize = 1 * KB;
 
   // Default segment size.
   static const intptr_t kSegmentSize = 64 * KB;
 
   // Zap value used to indicate deleted zone area (debug purposes).
   static const unsigned char kZapDeletedByte = 0x42;
 
@@ skipping 16 matching lines @@
 
 #if defined(DEBUG)
   // Dump the current allocated sizes in the zone object.
   void DumpZoneSizes();
 #endif
 
   // This buffer is used for allocation before any segments.
   // This would act as the initial stack allocated chunk so that we don't
   // end up calling malloc/free on zone scopes that allocate less than
   // kChunkSize
-  uint8_t buffer_[kInitialChunkSize];
+  COMPILE_ASSERT(kAlignment <= 8);
+  ALIGN8 uint8_t buffer_[kInitialChunkSize];
   MemoryRegion initial_buffer_;
 
   // The free region in the current (head) segment or the initial buffer is
   // represented as the half-open interval [position, limit). The 'position'
   // variable is guaranteed to be aligned as dictated by kAlignment.
   uword position_;
   uword limit_;
 
   // Zone segments are internal data structures used to hold information
   // about the memory segmentations that constitute a zone. The entire
@@ skipping 110 matching lines @@
             reinterpret_cast<void*>(old_data),
             Utils::Minimum(old_len * sizeof(ElementType),
                            new_len * sizeof(ElementType)));
   }
   return new_data;
 }
 
 }  // namespace dart
 
 #endif  // VM_ZONE_H_