Use the Code's pointer offsets to find object references when disassembling IA32.

runtime/vm/disassembler_dbc.cc

 // Copyright (c) 2016, 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/disassembler.h"
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_DBC.
 #if defined(TARGET_ARCH_DBC)
 
 #include "platform/assert.h"
 #include "vm/constants_dbc.h"
 #include "vm/cpu.h"
+#include "vm/instructions.h"
 
 namespace dart {
 
 static const char* kOpcodeNames[] = {
 #define BYTECODE_NAME(name, encoding, op1, op2, op3) #name,
     BYTECODES_LIST(BYTECODE_NAME)
 #undef BYTECODE_NAME
 };
 
 static const size_t kOpcodeCount =
@@ skipping 184 matching lines @@
     BYTECODES_LIST(BYTECODE_FORMATTER)
 #undef BYTECODE_FORMATTER
 };
 
 
 void Disassembler::DecodeInstruction(char* hex_buffer,
                                      intptr_t hex_size,
                                      char* human_buffer,
                                      intptr_t human_size,
                                      int* out_instr_size,
+                                     const Code& code,
+                                     Object** object,
                                      uword pc) {
   const uint32_t instr = *reinterpret_cast<uint32_t*>(pc);
   const uint8_t opcode = instr & 0xFF;
   ASSERT(opcode < kOpcodeCount);
   size_t name_size =
       OS::SNPrint(human_buffer, human_size, "%-10s\t", kOpcodeNames[opcode]);
 
   human_buffer += name_size;
   human_size -= name_size;
   kFormatters[opcode](human_buffer, human_size, pc, instr);
 
   OS::SNPrint(hex_buffer, hex_size, "%08x", instr);
   if (out_instr_size) {
     *out_instr_size = sizeof(uint32_t);
   }
+
+  *object = NULL;
+  if (!code.IsNull()) {
+    *object = &Object::Handle();
+    if (!DecodeLoadObjectFromPoolOrThread(pc, code, *object)) {
+      *object = NULL;
+    }
+  }
 }
 
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_DBC