Fix problems with sandboxing and the ARM integrated assembler.

src/IceAssembler.h

 //===- subzero/src/IceAssembler.h - Integrated assembler --------*- C++ -*-===//
 // 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.
 //
 // Modified by the Subzero authors.
 //
 //===----------------------------------------------------------------------===//
 //
 //                        The Subzero Code Generator
@@ skipping 14 matching lines @@
 
 #ifndef SUBZERO_SRC_ICEASSEMBLER_H
 #define SUBZERO_SRC_ICEASSEMBLER_H
 
 #include "IceDefs.h"
 #include "IceFixups.h"
 #include "IceUtils.h"
 
 namespace Ice {
 
+class Assembler;
+
 /// A Label can be in one of three states:
 ///  - Unused.
 ///  - Linked, unplaced and tracking the position of branches to the label.
 ///  - Bound, placed and tracking its position.
 class Label {
   Label(const Label &) = delete;
   Label &operator=(const Label &) = delete;
 
 public:
   Label() = default;
@@ skipping 30 matching lines @@
   bool isLinked() const { return Position > 0; }
 
   virtual bool isUnused() const { return Position == 0; }
 
   void bindTo(intptr_t position) {
     assert(!isBound());
     Position = -position - kWordSize;
     assert(isBound());
   }
 
-  void linkTo(intptr_t position) {
-    assert(!isBound());
-    Position = position + kWordSize;
-    assert(isLinked());
-  }
+  void linkTo(const Assembler &Asm, intptr_t position);
 
 protected:
   intptr_t Position = 0;
 
   // TODO(jvoung): why are labels offset by this?
   static constexpr uint32_t kWordSize = sizeof(uint32_t);
 };
 
 /// Assembler buffers are used to emit binary code. They grow on demand.
 class AssemblerBuffer {
@@ skipping 250 matching lines @@
 protected:
   // Buffer's constructor uses the Allocator, so it needs to appear after it.
   // TODO(jpp): dependencies on construction order are a nice way of shooting
   // yourself in the foot. Fix this.
   AssemblerBuffer Buffer;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEASSEMBLER_H_