Eliminate the type distinction between BindInstr and DoInstr.

runtime/vm/intermediate_language_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/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "lib/error.h"
@@ skipping 14 matching lines @@
 // on the stack and return the result in a fixed register RAX.
 LocationSummary* Computation::MakeCallSummary() {
   LocationSummary* result = new LocationSummary(0, 0, LocationSummary::kCall);
   result->set_out(Location::RegisterLocation(RAX));
   return result;
 }
 
 
 void BindInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   computation()->EmitNativeCode(compiler);
-  if (locs()->out().kind() == Location::kRegister) {
+  if (is_used() && locs()->out().kind() == Location::kRegister) {
     // TODO(vegorov): this should really happen only for comparisons fused
     // with branches.  Currrently IR does not provide an easy way to remove
     // instructions from the graph so we just leave fused comparison in it
     // but change its result location to be NoLocation.
     compiler->frame_register_allocator()->Push(locs()->out().reg(), this);
   }
 }
 
 
 LocationSummary* ReturnInstr::MakeLocationSummary() const {
@@ skipping 1933 matching lines @@
                                  instance_call()->argument_names());
   }
   __ Bind(&done);
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64