MemorySanitizer support.

runtime/vm/native_arguments.h

 // 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.
 
 #ifndef VM_NATIVE_ARGUMENTS_H_
 #define VM_NATIVE_ARGUMENTS_H_
 
 #include "platform/assert.h"
+#include "platform/memory_sanitizer.h"
 #include "vm/globals.h"
 #include "vm/handles_impl.h"
 #include "vm/simulator.h"
 #include "vm/stub_code.h"
 
 namespace dart {
 
 DECLARE_FLAG(bool, deoptimize_alot);
 DECLARE_FLAG(bool, trace_natives);
 DECLARE_FLAG(bool, verify_on_transition);
@@ skipping 63 matching lines @@
 // NOTE: Since we pass 'this' as a pass-by-value argument in the stubs we don't
 // have DISALLOW_COPY_AND_ASSIGN in the class definition and do not make it a
 // subclass of ValueObject.
 class NativeArguments {
  public:
   Isolate* isolate() const { return isolate_; }
   int ArgCount() const { return ArgcBits::decode(argc_tag_); }
 
   RawObject* ArgAt(int index) const {
     ASSERT((index >= 0) && (index < ArgCount()));
-    return (*argv_)[-index];
+    RawObject** arg_ptr = &((*argv_)[-index]);
+    // Tell MemorySanitizer the RawObject* was initialized (by generated code).
+    __msan_unpoison(arg_ptr, kWordSize);
+    return *arg_ptr;
   }
 
   int NativeArgCount() const {
     int function_bits = FunctionBits::decode(argc_tag_);
     return ArgCount() - NumHiddenArgs(function_bits);
   }
 
   RawObject* NativeArg0() const {
     int function_bits = FunctionBits::decode(argc_tag_);
     if (function_bits == (kClosureFunctionBit | kInstanceFunctionBit)) {
@@ skipping 116 matching lines @@
 
   Isolate* isolate_;  // Current isolate pointer.
   int argc_tag_;  // Encodes argument count and invoked native call type.
   RawObject*(*argv_)[];  // Pointer to an array of arguments to runtime call.
   RawObject** retval_;  // Pointer to the return value area.
 };
 
 }  // namespace dart
 
 #endif  // VM_NATIVE_ARGUMENTS_H_