VM: Array bounds checks that don't deoptimize for precompiled code.

runtime/vm/assembler_arm64.h

 // 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.
 
 #ifndef VM_ASSEMBLER_ARM64_H_
 #define VM_ASSEMBLER_ARM64_H_
 
 #ifndef VM_ASSEMBLER_H_
 #error Do not include assembler_arm64.h directly; use assembler.h instead.
 #endif
@@ skipping 1201 matching lines @@
   void SmiUntag(Register dst, Register src) {
     AsrImmediate(dst, src, kSmiTagSize);
   }
   void SmiTag(Register reg) {
     LslImmediate(reg, reg, kSmiTagSize);
   }
   void SmiTag(Register dst, Register src) {
     LslImmediate(dst, src, kSmiTagSize);
   }
 
+  void BranchIfNotSmi(Register reg, Label* label) {
+    tsti(reg, Immediate(kSmiTagMask));
+    b(label, NE);
+  }
+
   void Branch(const StubEntry& stub_entry,
               Register pp,
               Patchability patchable = kNotPatchable);
   void BranchPatchable(const StubEntry& stub_entry);
 
   void BranchLink(const StubEntry& stub_entry,
                   Patchability patchable = kNotPatchable);
 
   void BranchLinkPatchable(const StubEntry& stub_entry);
   void BranchLinkToRuntime();
@@ skipping 714 matching lines @@
                                   Register value,
                                   Label* no_update);
 
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(Assembler);
 };
 
 }  // namespace dart
 
 #endif  // VM_ASSEMBLER_ARM64_H_