VM: Fix a couple of issues in the AOT optimizer, add fast path smi multiply.

runtime/vm/intermediate_language_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"  // Needed here to get TARGET_ARCH_ARM64.
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/compiler.h"
@@ skipping 2816 matching lines @@
   __ b(slow_path->entry_label(), NE);
   switch (op_kind()) {
     case Token::kADD:
       __ adds(result, left, Operand(right));
       __ b(slow_path->entry_label(), VS);
       break;
     case Token::kSUB:
       __ subs(result, left, Operand(right));
       __ b(slow_path->entry_label(), VS);
       break;
+    case Token::kMUL:
+      __ SmiUntag(TMP, left);
+      __ mul(result, TMP, right);
+      __ smulh(TMP, TMP, right);
+      // TMP: result bits 64..127.
+      __ cmp(TMP, Operand(result, ASR, 63));
+      __ b(slow_path->entry_label(), NE);
+      break;
     case Token::kBIT_OR:
       // Operation may be part of combined smi check.
       if (!combined_smi_check) {
         __ orr(result, left, Operand(right));
       }
       break;
     case Token::kBIT_AND:
       __ and_(result, left, Operand(right));
       break;
     case Token::kBIT_XOR:
@@ skipping 2842 matching lines @@
                                 1,
                                 locs());
   __ Drop(1);
   __ Pop(result);
 }
 
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64