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

runtime/vm/simulator_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 <setjmp.h>  // NOLINT
 #include <stdlib.h>
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_ARM64)
 
@@ skipping 1671 matching lines @@
 
 void Simulator::DecodeExceptionGen(Instr* instr) {
   if ((instr->Bits(0, 2) == 1) && (instr->Bits(2, 3) == 0) &&
       (instr->Bits(21, 3) == 0)) {
     // Format(instr, "svc 'imm16");
     UnimplementedInstruction(instr);
   } else if ((instr->Bits(0, 2) == 0) && (instr->Bits(2, 3) == 0) &&
              (instr->Bits(21, 3) == 1)) {
     // Format(instr, "brk 'imm16");
     SimulatorDebugger dbg(this);
-    uint16_t imm = static_cast<uint16_t>(instr->Imm16Field());
-    char buffer[32];
-    snprintf(buffer, sizeof(buffer), "brk #0x%x", imm);
-    set_pc(get_pc() + Instr::kInstrSize);
-    dbg.Stop(instr, buffer);
+    int32_t imm = instr->Imm16Field();
+    if (imm == Instr::kStopMessageCode) {
+      const char* message = *reinterpret_cast<const char**>(
+          reinterpret_cast<intptr_t>(instr) - 2 * Instr::kInstrSize);
+      set_pc(get_pc() + Instr::kInstrSize);
+      dbg.Stop(instr, message);
+    } else {
+      char buffer[32];
+      snprintf(buffer, sizeof(buffer), "brk #0x%x", imm);
+      set_pc(get_pc() + Instr::kInstrSize);
+      dbg.Stop(instr, buffer);
+    }
   } else if ((instr->Bits(0, 2) == 0) && (instr->Bits(2, 3) == 0) &&
              (instr->Bits(21, 3) == 2)) {
     // Format(instr, "hlt 'imm16");
     uint16_t imm = static_cast<uint16_t>(instr->Imm16Field());
-    if (imm == Instr::kStopMessageCode) {
-      SimulatorDebugger dbg(this);
-      const char* message = *reinterpret_cast<const char**>(
-          reinterpret_cast<intptr_t>(instr) - 2 * Instr::kInstrSize);
-      set_pc(get_pc() + Instr::kInstrSize);
-      dbg.Stop(instr, message);
-    } else if (imm == Instr::kSimulatorBreakCode) {
+    if (imm == Instr::kSimulatorBreakCode) {
       SimulatorDebugger dbg(this);
       dbg.Stop(instr, "breakpoint");
     } else if (imm == Instr::kSimulatorRedirectCode) {
       DoRedirectedCall(instr);
     } else {
       UnimplementedInstruction(instr);
     }
   } else {
     UnimplementedInstruction(instr);
   }
@@ skipping 1776 matching lines @@
   set_register(NULL, kExceptionObjectReg, bit_cast<int64_t>(raw_exception));
   set_register(NULL, kStackTraceObjectReg, bit_cast<int64_t>(raw_stacktrace));
   buf->Longjmp();
 }
 
 }  // namespace dart
 
 #endif  // !defined(HOST_ARCH_ARM64)
 
 #endif  // defined TARGET_ARCH_ARM64