Background compilation work:

runtime/vm/assembler_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/globals.h"  // NOLINT
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/assembler.h"
 #include "vm/cpu.h"
 #include "vm/longjump.h"
@@ skipping 1059 matching lines @@
 
 
 void Assembler::RestoreCodePointer() {
   ldr(CODE_REG, Address(FP, kPcMarkerSlotFromFp * kWordSize));
   CheckCodePointer();
 }
 
 
 void Assembler::CheckCodePointer() {
 #ifdef DEBUG
+  Comment("CheckCodePointer");
   Label cid_ok, instructions_ok;
   Push(R0);
   CompareClassId(CODE_REG, kCodeCid);
   b(&cid_ok, EQ);
   brk(0);
   Bind(&cid_ok);
 
   const intptr_t entry_offset =
       CodeSize() + Instructions::HeaderSize() - kHeapObjectTag;
   adr(R0, Immediate(-entry_offset));
@@ skipping 66 matching lines @@
     set_constant_pool_allowed(false);
     // Restore and untag PP.
     LoadFromOffset(PP, FP, kSavedCallerPpSlotFromFp * kWordSize);
     sub(PP, PP, Operand(kHeapObjectTag));
   }
   LeaveFrame();
 }
 
 
 void Assembler::EnterCallRuntimeFrame(intptr_t frame_size) {
+  Comment("EnterCallRuntimeFrame");
   EnterStubFrame();
 
   // Store fpu registers with the lowest register number at the lowest
   // address.
   for (int i = kNumberOfVRegisters - 1; i >= 0; i--) {
     if ((i >= kAbiFirstPreservedFpuReg) && (i <= kAbiLastPreservedFpuReg)) {
       // TODO(zra): When SIMD is added, we must also preserve the top
       // 64-bits of the callee-saved registers.
       continue;
     }
@@ skipping 285 matching lines @@
     add(base, array, Operand(index, LSL, shift));
   }
   const OperandSize size = Address::OperandSizeFor(cid);
   ASSERT(Address::CanHoldOffset(offset, Address::Offset, size));
   return Address(base, offset, Address::Offset, size);
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64