Adds intrinsics for arm64.

runtime/vm/intermediate_language_x64.cc

 // Copyright (c) 2013, 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 "vm/dart_entry.h"
@@ skipping 2576 matching lines @@
   __ Bind(slow_path->exit_label());
 }
 
 
 static void EmitJavascriptOverflowCheck(FlowGraphCompiler* compiler,
                                         Range* range,
                                         Label* overflow,
                                         Register result) {
   if (!range->IsWithin(-0x20000000000000LL, 0x20000000000000LL)) {
     ASSERT(overflow != NULL);
+    // TODO(zra): This can be tightened to one compare/branch using:
+    // overflow = (result + 2^52) > 2^53 with an unsigned comparison.
     __ CompareImmediate(result, Immediate(-0x20000000000000LL), PP);
     __ j(LESS, overflow);
     __ CompareImmediate(result, Immediate(0x20000000000000LL), PP);
     __ j(GREATER, overflow);
   }
 }
 
 
 static void EmitSmiShiftLeft(FlowGraphCompiler* compiler,
                              BinarySmiOpInstr* shift_left) {
@@ skipping 3172 matching lines @@
                          PcDescriptors::kOther,
                          locs());
   __ Drop(ArgumentCount());  // Discard arguments.
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64