VM: Clean up and fix bugs in instructions patterns

runtime/vm/instructions_mips.cc

 // Copyright (c) 2013, 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.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_MIPS.
 #if defined(TARGET_ARCH_MIPS)
 
 #include "vm/constants_mips.h"
 #include "vm/cpu.h"
 #include "vm/instructions.h"
@@ skipping 100 matching lines @@
     ASSERT(instr->RsField() == *reg);
     ASSERT(instr->RtField() == PP);
 
     start -= Instr::kInstrSize;
     instr = Instr::At(start);
     ASSERT(instr->OpcodeField() == LUI);
     ASSERT(instr->RtField() == *reg);
     // Offset is signed, so add the upper 16 bits.
     offset += (instr->UImmField() << 16);
   }
-  offset += kHeapObjectTag;
-  ASSERT(Utils::IsAligned(offset, 4));
-  *index = (offset - Array::data_offset()) / 4;
+  *index = ObjectPool::IndexFromOffset(offset);
   return start;
 }
 
 
 RawICData* CallPattern::IcData() {
   if (ic_data_.IsNull()) {
     Register reg;
     args_desc_load_end_ =
         InstructionPattern::DecodeLoadObject(ic_data_load_end_,
                                              object_pool_,
@@ skipping 94 matching lines @@
 bool ReturnPattern::IsValid() const {
   Instr* jr = Instr::At(pc_);
   return (jr->OpcodeField() == SPECIAL) &&
          (jr->FunctionField() == JR) &&
          (jr->RsField() == RA);
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_MIPS