Merged from GC branch to bleeding_edge

src/ia32/macro-assembler-ia32.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2563 matching lines @@
   and_(Operand(length), Immediate(kStringEncodingMask));
   xor_(Operand(length), Immediate(kStringEncodingMask));
   add(Operand(length), Immediate(0x04));
   // Value now either 4 (if ASCII) or 8 (if UC16), i.e., char-size shifted
   // by 2. If we multiply the string length as smi by this, it still
   // won't overflow a 32-bit value.
   ASSERT_EQ(SeqAsciiString::kMaxSize, SeqTwoByteString::kMaxSize);
   ASSERT(SeqAsciiString::kMaxSize <=
          static_cast<int>(0xffffffffu >> (2 + kSmiTagSize)));
   imul(length, FieldOperand(value, String::kLengthOffset));
-  shr(length, 2 + kSmiTagSize);
+  shr(length, 2 + kSmiTagSize + kSmiShiftSize);
   add(Operand(length),
       Immediate(SeqString::kHeaderSize + kObjectAlignmentMask));
   and_(Operand(length),
        Immediate(~kObjectAlignmentMask));
 
   bind(&is_data_object);
   // Value is a data object, and it is white.  Mark it black.  Since we know
   // that the object is white we can make it black by flipping one bit.
   or_(Operand(bitmap_scratch, MemoryChunk::kHeaderSize), mask_scratch);
 
   and_(bitmap_scratch, Immediate(~Page::kPageAlignmentMask));
   add(Operand(bitmap_scratch, MemoryChunk::kLiveBytesOffset),
       length);
+  if (FLAG_debug_code) {
+    mov(length, Operand(bitmap_scratch, MemoryChunk::kLiveBytesOffset));
+    cmp(length, Operand(bitmap_scratch, MemoryChunk::kSizeOffset));
+    Check(less_equal, "Live Bytes Count overflow chunk size");
+  }
 
   bind(&done);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32