Use a breakpoint instruction for a stop message on arm instead of

runtime/vm/disassembler_arm64.cc

 // Copyright (c) 2014, 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_ARM64.
 #if defined(TARGET_ARCH_ARM64)
 #include "platform/assert.h"
 
@@ skipping 811 matching lines @@
 }
 
 
 void ARM64Decoder::DecodeExceptionGen(Instr* instr) {
   if ((instr->Bits(0, 2) == 1) && (instr->Bits(2, 3) == 0) &&
       (instr->Bits(21, 3) == 0)) {
     Format(instr, "svc 'imm16");
   } else if ((instr->Bits(0, 2) == 0) && (instr->Bits(2, 3) == 0) &&
              (instr->Bits(21, 3) == 1)) {
     Format(instr, "brk 'imm16");
+    if (instr->Imm16Field() == Instr::kStopMessageCode) {
+      const char* message = *reinterpret_cast<const char**>(
+          reinterpret_cast<intptr_t>(instr) - 2 * Instr::kInstrSize);
+      buffer_pos_ += OS::SNPrint(current_position_in_buffer(),
+                                 remaining_size_in_buffer(),
+                                 " ; \"%s\"",
+                                 message);
+    }
   } else if ((instr->Bits(0, 2) == 0) && (instr->Bits(2, 3) == 0) &&
              (instr->Bits(21, 3) == 2)) {
     Format(instr, "hlt 'imm16");
   } else {
     Unknown(instr);
   }
 }
 
 
 void ARM64Decoder::DecodeSystem(Instr* instr) {
@@ skipping 592 matching lines @@
   int32_t instruction_bits = Instr::At(pc)->InstructionBits();
   OS::SNPrint(hex_buffer, hex_size, "%08x", instruction_bits);
   if (out_instr_size) {
     *out_instr_size = Instr::kInstrSize;
   }
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM