[turbofan] Use cbz/cbnz when possible on arm64.

src/compiler/arm64/instruction-selector-arm64.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
@@ skipping 1252 matching lines @@
           return;
         }
         return VisitWordCompare(this, value, kArm64Tst, &cont, true,
                                 kLogical64Imm);
       }
       default:
         break;
     }
   }
 
-  // Branch could not be combined with a compare, emit compare against 0.
-  VisitWord32Test(this, value, &cont);
+  // Branch could not be combined with a compare, compare against 0 and branch.
+  DCHECK((cont.condition() == kEqual) || (cont.condition() == kNotEqual));
+  ArchOpcode opcode = (cont.condition() == kEqual) ? kArm64Cbz32 : kArm64Cbnz32;
+  Emit(opcode, NULL, g.UseRegister(value), g.Label(cont.true_block()),
+       g.Label(cont.false_block()))->MarkAsControl();
 }
 
 
 void InstructionSelector::VisitWord32Equal(Node* const node) {
   Node* const user = node;
   FlagsContinuation cont(kEqual, node);
   Int32BinopMatcher m(user);
   if (m.right().Is(0)) {
     Node* const value = m.left().node();
     if (CanCover(user, value)) {
@@ skipping 124 matching lines @@
 MachineOperatorBuilder::Flags
 InstructionSelector::SupportedMachineOperatorFlags() {
   return MachineOperatorBuilder::kFloat64Floor |
          MachineOperatorBuilder::kFloat64Ceil |
          MachineOperatorBuilder::kFloat64RoundTruncate |
          MachineOperatorBuilder::kFloat64RoundTiesAway;
 }
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8