Restrict objects printing in disassembler to avoid GC.

runtime/vm/disassembler_x64.cc

 // Copyright (c) 2012, 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_IA32.
 #if defined(TARGET_ARCH_X64)
 #include "platform/utils.h"
 #include "vm/allocation.h"
@@ skipping 752 matching lines @@
       break;
     }
     default:
       UNREACHABLE();
       break;
   }
   return advance;
 }
 
 
+static const char* ObjectToCStringNoGC(const Object& obj) {
+  if (obj.IsSmi() ||
+      obj.IsMint() ||
+      obj.IsDouble() ||
+      obj.IsString() ||
+      obj.IsNull() ||
+      obj.IsBool() ||
+      obj.IsClass() ||
+      obj.IsFunction() ||
+      obj.IsICData() ||
+      obj.IsField()) {
+    return obj.ToCString();
+  }
+
+  const Class& clazz = Class::CheckedHandle(obj.clazz());
+  const char* full_class_name = clazz.ToCString();
+  const char* format = "instance of %s";
+  intptr_t len = OS::SNPrint(NULL, 0, format, full_class_name) + 1;
+  char* chars = Isolate::Current()->current_zone()->Alloc<char>(len);
+  OS::SNPrint(chars, len, format, full_class_name);
+  return chars;
+}
+
+
 void DisassemblerX64::AppendAddressToBuffer(uint8_t* addr_byte_ptr) {
   NoGCScope no_gc;
   uword addr = reinterpret_cast<uword>(addr_byte_ptr);
   AppendToBuffer("0x%0"PRIxPTR, addr);
   // Try to print as heap object or stub name
   if (!Isolate::Current()->heap()->CodeContains(addr) &&
       Isolate::Current()->heap()->Contains(addr - kHeapObjectTag)) {
     Object& obj = Object::Handle(reinterpret_cast<RawObject*>(addr));
     if (obj.IsArray()) {
       const Array& arr = Array::CheckedHandle(obj.raw());
       intptr_t len = arr.Length();
       if (len > 5) len = 5;  // Print a max of 5 elements.
       AppendToBuffer("  Array[");
       int i = 0;
       while (i < len) {
         obj = arr.At(i);
         if (i > 0) AppendToBuffer(", ");
-        AppendToBuffer(obj.ToCString());
+        AppendToBuffer(ObjectToCStringNoGC(obj));
         i++;
       }
       if (i < arr.Length()) AppendToBuffer(", ...");
       AppendToBuffer("]");
       return;
     }
-    AppendToBuffer("  '%s'", obj.ToCString());
+    AppendToBuffer("  '%s'", ObjectToCStringNoGC(obj));
   } else {
     // 'addr' is not an object, but probably a code address.
     const char* name_of_stub = StubCode::NameOfStub(addr);
     if (name_of_stub != NULL) {
       AppendToBuffer("  [stub: %s]", name_of_stub);
     } else {
       // Print only if jumping to entry point.
       const Code& code = Code::Handle(Code::LookupCode(addr));
       if (!code.IsNull() && (code.EntryPoint() == addr)) {
         const Function& function = Function::Handle(code.function());
@@ skipping 1024 matching lines @@
                                   human_buffer,
                                   sizeof(human_buffer),
                                   pc);
     pc += instruction_length;
   }
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64